Water-based intumescent fire-retardant coating for steel structure and preparation method thereof

Abstract

The application discloses a kind of water-based intumescent steel structure fire-retardant coating, including A component and B component, mass ratio is 15:1-20:1;With mass parts, A component includes 20-40 parts of acrylic acid salt, 0-10 parts of water-based polyvinylidene chloride (PVDC) emulsion, 35-75 parts of intumescent flame retardant, 0.5-2 parts of organic alkali, 0.2-2 parts of reinforcing fiber, 5-20 parts of filler, 2-10 parts of auxiliary agent and 10-30 parts of water;With mass parts, B component includes 1-5 parts of curing accelerator and 5-20 parts of water.The application further provides the preparation method of the water-based intumescent steel structure fire-retardant coating and its construction technology.The fire-retardant coating of the application is environmentally friendly, can rapidly expand to form fire-resistant and heat-insulating protective layer when fire occurs, improve the fire resistance limit of steel structure, avoid building collapse caused by loss of support force of steel structure;Meanwhile, it has excellent corrosion resistance, weather resistance and vibration fatigue resistance.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials and fire-retardant coatings, specifically relating to a water-based intumescent fire-retardant coating for steel structures and its preparation method. Background Technology

[0002] Steel structures possess numerous advantages, including high strength, light weight, good plasticity and toughness, and excellent seismic performance. They are suitable for mechanized processing, have a high degree of industrialization, and short construction cycles, making them widely used in high-rise buildings, railways, bridges, factories, chemical equipment, stadiums, libraries, and other projects. Although steel is a non-combustible material, it has excellent thermal conductivity. When exposed to high temperatures (≥500℃), the physical properties of steel change significantly, its strength drops sharply, and it loses its load-bearing capacity, causing building collapse, resulting in incalculable economic losses and even casualties. Therefore, fire protection of steel structures has become a major concern. To improve the flame resistance and safety of steel structures, the use of fire-retardant coatings has become a common method.

[0003] Fire-retardant coatings for steel structures can be categorized into different types based on their fire-retardant mechanism, application range, coating thickness, and film-forming substances. Among these, thin-film intumescent fire-retardant coatings for steel structures have become a hot research and development area. With increasing environmental awareness, water-based fire-retardant coatings that do not use organic solvents, especially toxic and harmful organic solvents (such as toluene), are gaining increasing market favor. Simultaneously, fire-retardant coatings must possess comprehensive properties such as high adhesion strength to steel, long fire resistance time, and good corrosion resistance.

[0004] Polyacrylic acid resin is a commonly used film-forming substance in fire-retardant coatings, and it is generally a single-component system. However, polyacrylic acid resin has low solubility in organic solvents and water, requiring the addition of a large amount of diluent. This leads to problems such as sagging, slow drying speed, low coating adhesion, and cracking during fire-retardant coating application. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a water-based intumescent fire-retardant coating for steel structures. This fire-retardant coating uses acrylate as the film-forming substance and water as the solvent, exhibiting good adhesion to steel, long fire resistance time, and excellent corrosion resistance.

[0006] The present invention adopts the following technical solution:

[0007] A water-based intumescent fireproof coating for steel structures comprises component A and component B in a mass ratio of 15:1-20:1. Component A, by mass parts, comprises 20-40 parts acrylate, 0-10 parts water-based polyvinylidene chloride (PVDC) emulsion, 35-75 parts intumescent flame retardant, 0.5-2 parts organic alkali, 0.2-2 parts reinforcing fiber, 5-20 parts filler, 2-10 parts additives, and 10-30 parts water. The intumescent flame retardant is composed of a dehydration and charring catalyst, a foaming agent, and a charring agent in a mass ratio of (2.0-4.0):(0.5-2.0):(0.5-1.5).

[0008] By weight, component B comprises 1-5 parts of curing accelerator and 5-20 parts of water.

[0009] Preferably, by weight, component A comprises 30-35 parts modified acrylic resin, 4-6 parts waterborne polyvinylidene chloride (PVDC) emulsion, 45-55 parts intumescent flame retardant, 0.3-0.4 parts organic alkali, 1-1.5 parts reinforcing fiber, 10-15 parts filler, 3-5 parts additives, and 15-20 parts water.

[0010] Preferably, component B comprises 1.5-2 parts by weight of curing accelerator and 5-6 parts by weight of water.

[0011] Preferably, the acrylate is selected from at least one of magnesium acrylate, calcium acrylate, and sodium acrylate.

[0012] Preferably, the polyvinylidene chloride content of the aqueous polyvinylidene chloride emulsion is 20%-50%.

[0013] Preferably, the mass ratio of the dehydration and char formation catalyst, the foaming agent and the charring agent is (2-2.5):1:(0.8-1).

[0014] Preferably, the dehydration and carbonization catalyst is ammonium polyphosphate with a degree of polymerization greater than 1000.

[0015] Preferably, the foaming agent is selected from at least one of melamine and melamine phosphate.

[0016] Preferably, the char-forming agent is selected from at least one of pentaerythritol monopentaerythritol, dipentaerythritol, and pentaerythritol phosphate.

[0017] Preferably, the reinforcing fiber is selected from at least one of carbon fiber, basalt fiber, aluminosilicate fiber and zirconium oxide fiber.

[0018] Preferably, the length of the reinforcing fiber is 0.5-3.0 mm.

[0019] Preferably, the filler is selected from at least one of aluminum silicate powder, titanium dioxide, nano alumina, silica aerogel, wollastonite, zinc oxide, zinc borate, bentonite, kaolin, aluminum hydroxide, zirconium dioxide, antimony trioxide, boron nitride, and expandable graphite.

[0020] More preferably, the filler is selected from at least one of silica aerogel, titanium dioxide, and nano-alumina.

[0021] Most preferably, the filler is selected from all of silica aerogel, titanium dioxide and nano alumina.

[0022] The additives described in this invention refer to auxiliary materials for formulating coatings, which can improve the performance of coatings and promote film formation. They can be selected from at least one of thickeners, defoamers, dispersants, thixotropic agents and leveling agents.

[0023] As a preferred embodiment, the additives of the present invention include defoamers, dispersants, thixotropic agents and leveling agents, with each additive having a mass fraction of 0.5-1.5 parts.

[0024] The thickener, defoamer, dispersant, thixotropic agent, and leveling agent can be commercially available products commonly used in the art. As an illustrative embodiment, the defoamer can be BYK-014 manufactured by BYK Corporation, the dispersant can be BYK-4509 manufactured by BYK Corporation, the thixotropic agent can be BYK-420 manufactured by BYK Corporation, and the leveling agent can be BYK-3060 manufactured by BYK Corporation.

[0025] Preferably, the organic base is selected from at least one of triethanolamine and diethanolamine.

[0026] Preferably, the curing accelerator is selected from at least one of ammonium persulfate, sodium persulfate, and potassium persulfate.

[0027] Another objective of this invention is to provide a method for preparing the above-mentioned water-based intumescent fire-retardant coating for steel structures, comprising preparing and storing component A and component B separately, and mixing the two components according to a mass ratio when needed; the specific steps include:

[0028] S1. Prepare all raw materials according to the proportions;

[0029] Preparation of component S2.A

[0030] Add the intumescent flame retardant, reinforcing fiber, filler and additives to a pulverizer and grind and mix for 1-5 minutes. Then transfer to a container equipped with a stirrer containing acrylate, PVDC aqueous emulsion, organic base and water. Stir and mix for 5-10 minutes to obtain the final product. Store in a sealed container for later use.

[0031] Preparation of S3.B component

[0032] Add the curing accelerator to water and stir until the solution is clear. Store in a sealed container for later use.

[0033] S4. Time-based mixing

[0034] When ready for use, mix component A obtained in step S2 and component B obtained in step S3 according to the mass ratio until homogeneous.

[0035] Preferably, in step S4, an appropriate amount of water may be added to adjust the consistency of the coating if necessary.

[0036] In addition, another objective of this invention is to provide a construction process for the water-based intumescent fireproof coating for steel structures, comprising: cleaning the surface of the steel structure to be coated, and spraying or brushing the water-based intumescent fireproof coating for steel structures of this invention onto the surface of the steel structure once or multiple times until the dry film thickness reaches 3-4 mm.

[0037] In this instruction manual, the mass parts of each component represent the mass ratio between the components, not the actual mass number. Depending on the actual situation, 1 mass part can be any mass number, such as 1g, 5g, 10g, 50g, 250g, 500g, 1kg, 1 ton, etc.

[0038] The two-component fire-retardant coating of this invention is normally stored separately for each component. Based on the principle of "like dissolves like," the acrylate in component A is both well-compatible and dispersed with inorganic fillers and fibers, and also dissolves and disperses well with organic additives. Therefore, the coating of this invention exhibits good dispersion uniformity, which helps to maximize the protective efficacy of the coating. During use, the low molecular weight acrylate in component A acts as a precursor, undergoing free radical polymerization upon the addition of the curing accelerator in component B, which acts as an initiator, to generate an organic salt form of polyacrylate resin.

[0039]

[0040] Where M = Mg 2+ or Ca 2+ .

[0041] The water-based intumescent fire-retardant coating for steel provided by this invention is a reactive coating that easily forms a flexible chain network structure with multiple hydrogen bonds, ionic bonds, and a certain proportion. Therefore, the fire-retardant coating can maintain stable and durable adhesion to the steel substrate and resist stress cracking. Furthermore, when the fire-retardant coating of this invention is subjected to open flame combustion and high-temperature baking, the polyacrylate reacts with the raw material components to form a dense char layer and a new inorganic layer, resulting in better heat insulation performance.

[0042] In addition, acrylates have high solubility and good dispersibility in water, which can reduce the amount of water used, saving water resources and accelerating the drying of fire-retardant coatings to improve construction efficiency.

[0043] The water-based intumescent fireproof coating for steel structures of the present invention does not contain benzene and / or toluene or other VOCs in its raw materials, and therefore does not release harmful substances during preparation and construction, making it environmentally friendly and friendly to operators. Detailed Implementation

[0044] The present invention will be described below with reference to specific embodiments. Those skilled in the art will understand that these embodiments are for illustrative purposes only and do not limit the scope of the invention in any way.

[0045] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, all raw materials and reagents used in the following examples are commercially available products. The purchase details of some raw materials are as follows:

[0046] Magnesium acrylate, sodium acrylate, calcium acrylate: Nanjing Zhenzhi New Material Technology Co., Ltd.

[0047] Waterborne polyvinylidene chloride (PVDC) emulsion: Hubei Wande Chemical Co., Ltd., PVDC content 30%;

[0048] Ammonium polyphosphate (degree of polymerization greater than 1000), melamine, melamine phosphate, monopentaerythritol, dipentaerythritol: Nanjing Hualiming Science & Technology Co., Ltd.

[0049] Pentaerythritol phosphate: Qingyuan Prosefur Phosphate Chemical Co., Ltd.;

[0050] Silica aerogel, titanium dioxide, zinc oxide, zinc borate, zirconium dioxide, antimony trioxide: Nanjing Hualiming Science & Technology Co., Ltd.;

[0051] Carbon fiber, basalt fiber, aluminosilicate fiber: Alsay (Suzhou) Inorganic Materials Co., Ltd.;

[0052] Ammonium persulfate, sodium persulfate, potassium persulfate: Shanghai Maclean Biochemical Technology Co., Ltd.;

[0053] Triethanolamine, Diethanolamine: Shanghai Maclean Biochemical Technology Co., Ltd.;

[0054] Defoamer BYK-014, dispersant BYK-4509, thixotropic agent BYK-420, leveling agent BYK-3060: BYK Corporation.

[0055] In the following examples and comparative examples, components A and B were prepared using the following steps and processes:

[0056] S1. Weigh out the calculated amounts of each raw material according to the proportions;

[0057] Preparation of component S2.A

[0058] Add the intumescent flame retardant, reinforcing fiber, filler and additives to a pulverizer and grind and mix for 1-5 minutes. Then transfer to a container equipped with a stirrer containing acrylate, PVDC aqueous emulsion, organic base and water. Stir and mix for 5-10 minutes to obtain the final product. Store in a sealed container for later use.

[0059] Preparation of S3.B component

[0060] Mix the curing accelerator and water in a container equipped with a stirrer for 5-10 minutes to obtain a clear solution, which is component B. Store it in a sealed container for later use.

[0061] Examples 1-6 A water-based intumescent fireproof material for steel structures

[0062] The water-based intumescent steel structure fireproof material described in Examples 1-6 is composed of component A and component B. The raw material composition of the two components is shown in Table 1, where 1 part by mass = 1 kg.

[0063] Component A and component B are prepared separately according to the above method. Then, components A and B are mixed at a mass ratio of A:B = 17-17.5:1 and stirred evenly to obtain the water-based intumescent fireproof coating for steel structures. The coating is applied in multiple coats to the cleaned steel structure, and after drying and curing, an intumescent fireproof coating with a thickness of 3-4 mm is obtained.

[0064] Table 1. Raw material composition of water-based intumescent fireproof materials for steel structures in Examples 1-6 (unit: parts by mass)

[0065]

[0066] Comparative Examples 1-4 A water-based intumescent fireproof material for steel structures

[0067] The water-based intumescent steel structure fireproof materials described in Comparative Examples 1-4 are composed of component A and component B. The raw material composition of the two components is shown in Table 2, where 1 part by mass = 1 kg.

[0068] Component A and component B are prepared separately according to the above method. Then, components A and B are mixed at a mass ratio of A:B = 17-17.5:1 and stirred evenly to obtain the water-based intumescent fireproof coating for steel structures. The coating is applied in multiple coats to the cleaned steel structure, and after drying and curing, an intumescent fireproof coating with a thickness of 3-4 mm is obtained.

[0069] Table 2. Raw material composition of water-based intumescent fireproof materials for steel structures (Comparative Examples 1-4) (Unit: parts by mass)

[0070]

[0071] Test example: Performance testing of fire-retardant coatings in Examples 1-6 and Comparative Examples 1-4

[0072] The performance of the fire-retardant coatings in each example and comparative example was tested in accordance with GB 14907-2018 "Fire-retardant Coatings for Steel Structures" and GB / T 13477.10-2017 "Test Methods for Building Sealing Materials - Part 10: Determination of Tensile Adhesion". The results are shown in Tables 3 and 4, respectively.

[0073] The test results show that the water-based intumescent fireproof coating for steel structures provided in this embodiment of the invention has excellent fireproof performance. The char layer formed after the fire resistance test can expand by more than 35 times, and the expanded char layer is dense and has high strength.

[0074] In summary, the water-based intumescent fire-retardant coating of the present invention can meet the performance requirements of GB 14907-2018 "Fire-retardant Coatings for Steel Structures". It rapidly expands to form a fire-resistant and heat-insulating protective layer when a fire occurs, thereby improving the fire resistance limit of the steel structure and preventing the building from collapsing due to loss of support. At the same time, it is highly resistant to corrosion and weathering, and resistant to vibration fatigue.

[0075] Table 3. Results of main performance tests of fire-retardant coatings and fire-retardant coatings in Examples 1-6

[0076]

[0077] Table 4. Results of main performance tests for fire-retardant coatings and fire-retardant coatings in Comparative Examples 1-4

[0078]

Claims

1. A water-based intumescent fire-retardant coating for steel structures, comprising component A and component B in a mass ratio of 15:1-20:1; by mass parts, component A comprises 30-35 parts of acrylate, 4-6 parts of water-based polyvinylidene chloride (PVDC) emulsion, 45-55 parts of intumescent flame retardant, 0.3-0.4 parts of organic alkali, 1-1.5 parts of reinforcing fiber, 10-15 parts of filler, 3-5 parts of additives, and 15-20 parts of water; wherein, The acrylate is selected from at least one of magnesium acrylate, calcium acrylate, and sodium acrylate; the intumescent flame retardant is composed of a dehydration charring catalyst, a foaming agent, and a charring agent in a mass ratio of (2.0-4.0):(0.5-2.0):(0.5-1.5), wherein the dehydration charring catalyst is ammonium polyphosphate with a degree of polymerization greater than 1000, the foaming agent is selected from at least one of melamine and melamine phosphate, and the charring agent is selected from at least one of pentaerythritol mono-, pentaerythritol di-, and pentaerythritol phosphate; the organic base is selected from at least one of triethanolamine and diethanolamine; the filler is selected from all of silica aerogel, titanium dioxide, and nano-alumina. By weight, component B consists of 1.5-2 parts of curing accelerator and 5-6 parts of water; the curing accelerator is selected from at least one of ammonium persulfate, sodium persulfate and potassium persulfate.

2. The water-based intumescent fireproof coating for steel structures according to claim 1, characterized in that, The waterborne polyvinylidene chloride emulsion has a polyvinylidene chloride content of 20%-50%.

3. The water-based intumescent fireproof coating for steel structures according to claim 1, characterized in that, The mass ratio of the dehydration and char formation catalyst, foaming agent and char formation agent is (2-2.5):1:(0.8-1).

4. The water-based intumescent fireproof coating for steel structures according to claim 1, characterized in that, The reinforcing fiber is selected from at least one of carbon fiber, basalt fiber, aluminosilicate fiber and zirconium oxide fiber.

5. The water-based intumescent fireproof coating for steel structures according to claim 4, characterized in that, The length of the reinforcing fiber is 0.5-3.0 mm.

6. The water-based intumescent fireproof coating for steel structures according to claim 1, characterized in that, The additives include defoamers, dispersants, thixotropic agents, and leveling agents, with each additive comprising 0.5-1.5 parts by weight.

7. The water-based intumescent fireproof coating for steel structures according to claim 6, characterized in that, The defoamer is BYK-014 manufactured by BYK Corporation, the dispersant is BYK-4509 manufactured by BYK Corporation, the thixotropic agent is BYK-420 manufactured by BYK Corporation, and the leveling agent is BYK-3060 manufactured by BYK Corporation.

8. A method for preparing the water-based intumescent fire-retardant coating for steel structures according to any one of claims 1 to 7, comprising preparing and storing component A and component B separately, and mixing the two components according to a mass ratio when needed; the specific steps include: S1. Prepare all raw materials according to the proportions; S2. Preparation of Component A Add the intumescent flame retardant, reinforcing fiber, filler and additives to a pulverizer and grind and mix for 1-5 minutes. Then transfer to a container equipped with a stirrer containing acrylate, PVDC aqueous emulsion, organic base and water. Stir and mix for 5-10 minutes to obtain the final product. Store in a sealed container for later use. S3. Preparation of Component B Add the curing accelerator to water and stir until the solution is clear. Store in a sealed container for later use. S4. Time-based mixing When ready for use, mix component A obtained in step S2 and component B obtained in step S3 according to the mass ratio until homogeneous.

9. The preparation method according to claim 8, characterized in that, In step S4, an appropriate amount of water is added to adjust the consistency of the coating.

10. The construction process of the water-based intumescent fire-retardant coating for steel structures according to any one of claims 1 to 7, or the water-based intumescent fire-retardant coating for steel structures prepared according to the preparation method of claim 8 or 9, comprising: Clean the steel structure surface to be coated, and spray or brush the water-based intumescent fireproof coating onto the steel structure surface once or multiple times until the dry film thickness reaches 3-4 mm.

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