Water-based ultrathin intumescent flame-retardant super-hydrophobic steel coating and preparation method thereof

Abstract

The invention relates to a water-based ultrathin intumescent flame-retardant super-hydrophobic steel coating and a preparation method thereof, and the water-based ultrathin intumescent flame-retardant super-hydrophobic steel coating is prepared by the following steps: (1) dispersing ammonium polyphosphate in an organic solvent, dropwise adding a modifier into the solution, and reacting to obtain modified ammonium polyphosphate; (2) dispersing the low-melting-point glass in a mixed solution of ethanol and water, and adding a silane coupling agent to obtain super-hydrophobic low-melting-point glass; and (3) mixing the modified ammonium polyphosphate, low-melting-point glass and a water-based emulsion to prepare the water-based ultrathin intumescent flame-retardant steel coating. The water-based ultrathin intumescent flame-retardant steel coating has good hydrophobic performance, the problem that an existing water-based ultrathin intumescent flame-retardant steel coating is poor in water resistance is solved, and the fire resistance limit of the water-based ultrathin intumescent flame-retardant steel coating reaches 3 hours and is far higher than that of a water-based ultrathin steel coating at the present stage.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and in particular relates to a water-based ultra-thin intumescent flame-retardant super-hydrophobic steel coating and a preparation method thereof. Background Art

[0002] In contemporary building structures, steel structures, as one of the most cost-effective materials, are widely used in super high-rise buildings and large-span building structures. Steel structures have the advantages of light weight, high strength, large space, large span, good seismic performance, convenient construction and low environmental pollution, and have gradually become the mainstream in the era of green buildings. However, steel has poor heat resistance, and its mechanical properties will decrease with the increase of temperature in high temperature environments such as fires. When the temperature is higher than 550℃, the strength of steel components drops sharply, thus losing their bearing capacity, causing huge deformations and causing the building to become unstable or collapse.

[0003] With the continuous development of the steel structure construction industry and the continuous improvement of construction standards, the requirements for steel structure fire protection performance are getting higher and higher. It is very important to study steel structure fire retardant coatings with excellent performance. However, at present, the strength of the expanded carbon layer of ultra-thin water-based steel structure fire retardant coatings after flame combustion is significantly reduced, the stability of the carbon layer in the flame is reduced, and the fire resistance limit of the coating becomes smaller; the base material of water-based steel structure fire retardant coatings is mostly water-based resins, which are prone to blistering and cracking after being affected by external factors for a long time. In addition, traditional flame retardants have low water solubility and are easily precipitated from the coating film over time, resulting in poor fire protection effect of the coating and slowly losing its fire protection ability. Summary of the invention

[0004] In view of this, the present invention provides a water-based ultra-thin intumescent flame-retardant super-hydrophobic steel coating, and the preparation steps are as follows:

[0005] (1) dispersing ammonium polyphosphate in an organic solvent, adding a modifier dropwise into the solution, setting the temperature and time, filtering and drying after the reaction is completed to obtain modified ammonium polyphosphate;

[0006] (2) dispersing the low-melting-point glass in a mixture of ethanol and water, adding a silane coupling agent, setting the temperature and time, filtering, and drying to obtain a super-hydrophobic low-melting-point glass;

[0007] (3) The modified ammonium polyphosphate, low melting point glass and aqueous emulsion are mixed and stirred to react to prepare an aqueous ultra-thin intumescent flame-retardant steel coating.

[0008] Preferably according to the present invention, in step (1), the organic solvent is one or a combination of tetrahydrofuran, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0009] Preferably, according to the present invention, in step (1), the modifier is one or a combination of silicone, epoxy resin, and polyurethane.

[0010] Preferably according to the present invention, in step (1), the mass ratio of ammonium polyphosphate to the organic solvent is (1-400):1.

[0011] Preferably according to the present invention, in step (1), the temperature is 40-200° C. and the reaction time is 1 h-24 h.

[0012] Preferably according to the present invention, in step (2), the mass ratio of the low melting point glass to the silane coupling agent is (1-1000):1.

[0013] Preferably, according to the present invention, in step (2), the silane coupling agent is one or a combination of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethylsiloxane, polydimethylsiloxane, and methyltrichlorosilane.

[0014] Preferably according to the present invention, in step (3), the aqueous emulsion is one or a combination of acrylic emulsion, styrene acrylic emulsion, polyurethane emulsion, epoxy resin emulsion.

[0015] Preferably, according to the present invention, in step (3), the mass ratio of ammonium polyphosphate, low melting point glass and aqueous emulsion is (1-20):(1-10):100.

[0016] The beneficial technical effects of the present invention are:

[0017] 1. After modification, ammonium polyphosphate has better dispersibility in emulsion and is compatible with polymers.

[0018] 2. The coating has super hydrophobic properties, which significantly improves the water resistance of the coating.

[0019] 3. Modified ammonium polyphosphate and low-melting point glass have a synergistic effect, effectively improving the fire resistance limit of the coating.

[0020] 4. The fire resistance limit of the coating formed by the paint is 3h. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the combustion expansion diagram of the coating prepared by the water-based ultra-thin intumescent flame-retardant super-hydrophobic steel coating in Example 1. DETAILED DESCRIPTION

[0022] Hereinafter, the present invention will be described in detail. Before describing, it should be understood that the terms used in this specification and the appended claims should not be interpreted as being limited to the general meaning and dictionary meaning, but should be interpreted according to the meaning and concept corresponding to the technical aspects of the present invention on the basis of the principle that the inventor is allowed to appropriately define the terms for the best interpretation. Therefore, the descriptions presented here are only preferred examples for illustrative purposes and are not intended to limit the scope of the present invention, so that it should be understood that other equivalents or improvements can be obtained therefrom without departing from the spirit and scope of the present invention.

[0023] The following examples are only listed as examples of embodiments of the present invention and do not constitute any limitation to the present invention. It can be understood by those skilled in the art that modifications within the scope of the essence and concept of the present invention fall within the scope of protection of the present invention. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products.

[0024] Example 1

[0025] A water-based ultra-thin intumescent flame-retardant super-hydrophobic steel coating is prepared by the following steps:

[0026] (1) 40.0 g of ammonium polyphosphate and 20 ml of tetrahydrofuran were added to a three-necked flask, the pH of the system was adjusted to 1-3, and then the temperature was raised to 70°C, 8.0 g of waterborne polyurethane was added dropwise to the three-necked flask, and the reaction was continued for 5 hours. The mixture was cooled to room temperature, the solvent and reaction by-products were removed by a rotary evaporator, and the product after rotary evaporation was placed in a vacuum oven at 80°C and dried for 24 hours to obtain modified ammonium polyphosphate.

[0027] (2) Preparation of superhydrophobic low-melting-point glass

[0028] 10.0 g of low-melting-point glass was dispersed in a mixed solution of ethanol and water, the pH was adjusted to 8, 0.1 g of silane coupling agent was added, and the mixture was reacted at 80° C. for 24 h to obtain a super-hydrophobic low-melting-point glass.

[0029] (3) Preparation of water-based ultra-thin intumescent flame-retardant steel coating

[0030] 1 g of modified ammonium polyphosphate and 1 g of super-hydrophobic low-melting-point glass were added to 100 g of aqueous polyurethane emulsion, and the mixture was stirred and dispersed evenly to obtain an aqueous ultra-thin intumescent flame-retardant super-hydrophobic steel coating.

[0031] Example 2

[0032] A water-based ultra-thin intumescent flame-retardant super-hydrophobic steel coating is prepared by the following steps:

[0033] (1) 40.0 g of ammonium polyphosphate and 25 ml of tetrahydrofuran were added to a three-necked flask, the pH of the system was adjusted to 1-3, and then the temperature was raised to 70°C, 10.0 g of waterborne polyurethane was added dropwise to the three-necked flask, and the reaction was continued for 5 hours. The mixture was cooled to room temperature, the solvent and reaction by-products were removed by a rotary evaporator, and the product after rotary evaporation was placed in a vacuum oven at 80°C and dried for 24 hours to obtain modified ammonium polyphosphate.

[0034] (2) Preparation of superhydrophobic low-melting-point glass

[0035] 10.0 g of low-melting-point glass was dispersed in a mixed solution of ethanol and water, the pH was adjusted to 8, 0.2 g of silane coupling agent was added, and the mixture was reacted at 80° C. for 24 h to obtain a super-hydrophobic low-melting-point glass.

[0036] (3) Preparation of water-based ultra-thin intumescent flame-retardant steel coating

[0037] 1 g of modified ammonium polyphosphate and 1 g of super-hydrophobic low-melting-point glass were added to 100 g of aqueous polyurethane emulsion, and the mixture was stirred and dispersed evenly to obtain an aqueous ultra-thin intumescent flame-retardant super-hydrophobic steel coating.

[0038] Example 3

[0039] A water-based ultra-thin intumescent flame-retardant super-hydrophobic steel coating is prepared by the following steps:

[0040] (1) 40.0 g of ammonium polyphosphate and 20 ml of tetrahydrofuran were added to a three-necked flask, the pH of the system was adjusted to 1-3, and then the temperature was raised to 70°C, 10.0 g of waterborne polyurethane was added dropwise to the three-necked flask, and the reaction was continued for 5 hours. The mixture was cooled to room temperature, the solvent and reaction by-products were removed by a rotary evaporator, and the product after rotary evaporation was placed in a vacuum oven at 80°C and dried for 24 hours to obtain modified ammonium polyphosphate.

[0041] (2) Preparation of superhydrophobic low-melting-point glass

[0042] 10.0 g of low-melting-point glass was dispersed in a mixed solution of ethanol and water, the pH was adjusted to 8, 0.5 g of silane coupling agent was added, and the mixture was reacted at 80° C. for 24 h to obtain a super-hydrophobic low-melting-point glass.

[0043] (3) Preparation of water-based ultra-thin intumescent flame-retardant steel coating

[0044] 1.5 g of modified ammonium polyphosphate and 1.5 g of super-hydrophobic low-melting-point glass were added to 100 g of aqueous polyurethane emulsion, and the mixture was stirred and dispersed evenly to obtain an aqueous ultra-thin intumescent flame-retardant super-hydrophobic steel coating.

[0045] Comparative Example 1

[0046] A water-based ultra-thin intumescent flame-retardant steel coating, which differs from Example 1 in that no super-hydrophobic low-melting-point glass is added, is prepared by the following steps:

[0047] (1) 40.0 g of ammonium polyphosphate and 20 ml of tetrahydrofuran were added to a three-necked flask, the pH of the system was adjusted to 1-3, and then the temperature was raised to 70°C, 8.0 g of waterborne polyurethane was added dropwise to the three-necked flask, and the reaction was continued for 5 hours. The mixture was cooled to room temperature, the solvent and reaction by-products were removed by a rotary evaporator, and the product after rotary evaporation was placed in a vacuum oven at 80°C and dried for 24 hours to obtain modified ammonium polyphosphate.

[0048] (2) Preparation of water-based ultra-thin intumescent flame-retardant steel coating

[0049] 1 g of modified ammonium polyphosphate was added to 100 g of waterborne polyurethane emulsion, and the mixture was stirred and dispersed evenly to obtain a waterborne ultra-thin intumescent flame-retardant steel coating.

[0050] Comparative Example 2

[0051] A water-based ultra-thin intumescent flame-retardant super-hydrophobic steel coating, which differs from Example 1 in that modified ammonium polyphosphate is not added, is prepared by the following steps:

[0052] (1) Preparation of superhydrophobic low-melting-point glass

[0053] 10.0 g of low-melting-point glass was dispersed in a mixed solution of ethanol and water, the pH was adjusted to 8, 0.1 g of silane coupling agent was added, and the mixture was reacted at 80° C. for 24 h to obtain a super-hydrophobic low-melting-point glass.

[0054] (2) Preparation of water-based ultra-thin intumescent flame-retardant steel coating

[0055] 1 g of super-hydrophobic low-melting-point glass was added to 100 g of aqueous polyurethane emulsion, and the mixture was stirred and dispersed evenly to obtain an aqueous ultra-thin intumescent flame-retardant super-hydrophobic steel coating.

[0056] Results test:

[0057] The prepared coating was applied to a steel plate by blade coating or roller coating with a thickness of about 2 mm, and performance testing was performed.

[0058] (1) Test of hydrophobic effect

[0059] The coating contact angle in Example 1 is 151°, the contact angle in Example 2 is 150°, and the contact angle in Example 3 is 150°, which has good hydrophobicity.

[0060] (2) Fire resistance test

[0061] The fire resistance limit of the coating (duration of temperature less than 300°C) was tested by simulating a large plate combustion experiment. The fire resistance limit of the sample in Example 1 is 3h, the fire resistance limit of the sample in Example 2 is 2.5h, and the fire resistance limit of the sample in Example 3 is 2.5h. The fire resistance limit of the coating in Comparative Example 1 is 30min, and the fire resistance limit of the coating in Comparative Example 2 is 50min. This shows that the modified ammonium polyphosphate and the low-melting point glass have a synergistic effect, which effectively improves the fire resistance limit of the coating. The main reason is that ammonium polyphosphate expands when exposed to fire to form a carbon layer with weak strength. The modified ammonium polyphosphate has good dispersibility in aqueous emulsion and good compatibility with low-melting point glass. After combustion, the low-melting point glass forms a hard ceramic body, which greatly enhances the strength of the carbon layer, thereby significantly improving the fire resistance limit of the coating.

Claims

1. A water-based ultra-thin intumescent flame-retardant super-hydrophobic steel coating, characterized in that: The preparation steps are as follows: (1) dispersing ammonium polyphosphate in an organic solvent, adding a modifier dropwise into the solution, setting the temperature and time, filtering and drying after the reaction is completed to obtain modified ammonium polyphosphate; (2) dispersing the low-melting-point glass in a mixture of ethanol and water, adding a silane coupling agent, setting the temperature and time, filtering, and drying to obtain a super-hydrophobic low-melting-point glass; (3) The modified ammonium polyphosphate, low melting point glass and aqueous emulsion are mixed and stirred to react to prepare an aqueous ultra-thin intumescent flame-retardant steel coating.

2. The method according to claim 1, characterized in that In step (1), the organic solvent is one or a combination of tetrahydrofuran, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

3. The method according to claim 1, characterized in that In step (1), the modifier is one or a combination of silicone, epoxy resin, and polyurethane.

4. The method according to claim 1, characterized in that: In step (1), the mass ratio of ammonium polyphosphate to organic solvent is (1-400):

1.

5. The method according to claim 1, characterized in that: In step (1), the temperature is 40-200° C. and the reaction time is 1 h-24 h.

6. The method according to claim 1, characterized in that In step (2), the mass ratio of the low melting point glass to the silane coupling agent is (1-1000):

1.

7. The method according to claim 1, characterized in that In step (2), the silane coupling agent is one or a combination of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethylsiloxane, polydimethylsiloxane, and methyltrichlorosilane.

8. The method according to claim 1, characterized in that: In step (3), the aqueous emulsion is one or a combination of acrylic emulsion, styrene acrylic emulsion, polyurethane emulsion, and epoxy resin emulsion.

9. The method according to claim 1, characterized in that: In step (3), the mass ratio of ammonium polyphosphate, low melting point glass and aqueous emulsion is (1-20):(1-10):100.

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