Hydrogel flame-retardant material with strong adhesion and efficient flame retardance as well as preparation method and application of hydrogel flame-retardant material

Abstract

The invention discloses a hydrogel flame-retardant material with strong adhesion and efficient flame retardance as well as a preparation method and application thereof, and belongs to the technical field of flame-retardant materials. The preparation method comprises the following steps: adding water-absorbent resin and a flame retardant into ethanol in proportion, performing magnetic stirring, then performing low-temperature ultrasonic treatment to obtain a suspension, drying and crushing to obtain composite flame-retardant material powder, adding the composite flame-retardant material powder into water, and fully swelling to obtain the hydrogel flame-retardant material with strong adhesion and efficient flame retardance. The fire extinguishing agent can resist flame burning of a butane spray gun at the temperature of 1800 DEG C, and can be widely applied to areas with high wildfire disaster risk, such as forests and suburban areas.

Description

Technical Field

[0001] This invention belongs to the field of flame retardant materials technology, specifically relating to a hydrogel flame retardant material with both strong adhesion and high flame retardancy, its preparation method, and its application. Background Technology

[0002] Global wildfire hazards continue to escalate due to climate change, with the fire risk being most severe in border areas (WUI). Faced with this increasingly serious fire situation, there is an urgent need to develop long-term prevention and control technologies applicable to diverse scenarios. Water has an outstanding high specific heat capacity (c M (H2O)=75.9kJ·mol -1 ·K -1 ) and high vaporization enthalpy (ΔH vap[H2O=41.42kJ·mol) -1 Fire extinguishing agent (FCA) has become the most commonly used fire extinguishing agent. However, its high fluidity makes it difficult to stay effectively on the surface of the substrate, and a large amount is lost during the fire extinguishing process, which significantly limits the fire extinguishing efficiency. Even if it briefly covers the substrate, it will evaporate rapidly due to heat, resulting in a very short fire protection time.

[0003] Sodium polyacrylate (PANa) superabsorbent polymer, as a three-dimensional network structure, possesses excellent water absorption, is safe and environmentally friendly. After absorbing water, it forms a hydrogel that can firmly adhere to the substrate surface through in-situ film formation, thereby forming a physical barrier layer to isolate flames. It shows potential for long-lasting protection in the field of hydrogel fire extinguishing agents. In the prior art, patent document CN110404225A discloses an environmentally friendly polymeric colloidal fire extinguishing additive. This additive involves dissolving methylcellulose and polyacrylic acid, mixing them with an aqueous solution of metal salts, adding glutaraldehyde for crosslinking, drying, and then mixing with a flame retardant and a hydrocarbon surfactant. The resulting polymeric colloidal fire extinguishing additive exhibits outstanding temperature-sensitive properties, undergoing a sol-gel phase change with changes in ambient temperature. During fire extinguishing, it transforms into a highly viscous gel that adheres to the surface of the burning material, providing heat absorption and cooling, and oxygen isolation to suffocate the burning material, preventing further combustion and improving the fire extinguishing performance of water. This solves the problems of excessive viscosity, poor fluidity, and nozzle clogging during delivery and fire extinguishing associated with traditional polymeric hydrogels. Patent document CN111875909A discloses a composite flame-retardant heat-insulating and cooling material and its thixotropic hydrogel. This material is prepared by a composite process using a superabsorbent resin, water-soluble metal salts, water-soluble polysaccharide hydrosols, water-insoluble inorganic particles, and a modifier. When mixed with water, it forms a hydrogel that comprehensively blocks heat conduction, convection, and radiation, while also exhibiting thixotropic properties. However, this existing technology still cannot simultaneously achieve both strong adhesion and highly effective flame retardancy.

[0004] When sodium polyacrylate superabsorbent polymer is used in hydrogel fire extinguishing agents, flame retardants such as polyphosphates, alkalis and alkaline earth metal salts and inorganic salt dispersants are often added to further improve the flame retardant performance on the basis of strong adhesion. Among them, ammonium polyphosphate (APP) has high flame retardancy and environmental protection, and its use in developing hydrogel fire extinguishing agents with both strong adhesion and high flame retardancy has great application potential. Summary of the Invention

[0005] In view of this, the main objective of the present invention is to provide a method for preparing hydrogel flame retardant materials that have both strong adhesion and high flame retardancy, which is simple and easy to scale up.

[0006] Another objective of this invention is to provide a hydrogel flame retardant material that combines strong adhesion and high flame retardancy. This material is prepared by the method described above and has both strong adhesion and high flame retardancy properties. It exhibits significant flame retardant effects and can withstand the burning of a butane torch flame at 1800°C.

[0007] Another object of the present invention is to provide the application of the hydrogel flame-retardant material, which combines strong adhesion and high flame retardancy, in hydrogel fire extinguishing agents.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a hydrogel flame-retardant material that combines strong adhesion and high flame retardancy, comprising the following steps:

[0010] (1) Preparation of suspension: Add water-absorbing resin and flame retardant to ethanol in proportion, stir magnetically first, and then sonicate at low temperature to obtain suspension;

[0011] (2) Drying and pulverizing: The suspension is dried and pulverized to obtain composite flame retardant material powder;

[0012] (3) Water absorption and swelling: The composite flame retardant material powder is added to water and fully swelled to obtain the final product.

[0013] Preferably, in step (1), the absorbent resin is selected from one or more of sodium polyacrylate, polyacrylamide, and polyacrylonitrile.

[0014] Preferably, in step (1), the flame retardant is selected from one or more of ammonium polyphosphate, ammonium phosphate, diammonium hydrogen phosphate, sodium phosphate, disodium hydrogen phosphate, and phytic acid.

[0015] Preferably, in step (1), the mass ratio of the water-absorbing resin to the flame retardant is 1-3:1-3.

[0016] More preferably, in step (1), the water-absorbing resin is sodium polyacrylate, the flame retardant is ammonium polyphosphate, and the mass ratio of the two is 2:1.

[0017] Preferably, in step (1), the magnetic stirring speed is 800 rpm and the magnetic stirring time is 15 min.

[0018] Preferably, in step (1), the low-temperature ultrasound temperature is 5-15℃ and the low-temperature ultrasound time is 30min.

[0019] Preferably, in step (2), the drying conditions include drying at 110°C for 8 hours.

[0020] Preferably, in step (3), the mass fraction of the composite flame retardant material powder is 1-17 wt%.

[0021] In a second aspect, the present invention provides a hydrogel flame retardant material that combines strong adhesion and high flame retardancy, which is prepared by a method for preparing the hydrogel flame retardant material with strong adhesion and high flame retardancy.

[0022] A third aspect of the present invention provides the application of the hydrogel flame-retardant material, which combines strong adhesion and high flame retardancy, in hydrogel fire extinguishing agents.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] This invention proposes a hydrogel flame retardant material that combines strong adhesion and high-efficiency flame retardancy. It has the characteristics of adhering to the substrate, isolating air, and absorbing moisture and cooling. By adhering to the surface of combustibles through its own hydroxyl groups, it isolates a large amount of heat, limits the burning of the substrate by the flame, effectively covers the surface of combustibles, and avoids charring. It can be widely used in hydrogel fire extinguishing agents in areas with high risk of wildfire disasters, such as forests and suburban areas. Attached Figure Description

[0025] Figure 1 The Fourier transform infrared (FT-IR) spectra of APP, PANa, and the prepared PANa / APP composite flame retardant material in Example 1 are shown.

[0026] Figure 2 The image shows a scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) image of the PANa / APP composite flame retardant material prepared in Example 1.

[0027] Figure 3 The swelling ratios of the PANa / APP composite flame retardant material prepared in Example 1 and PANa without APP in deionized water, tap water, and river water are shown.

[0028] Figure 4The images show inverted images and rheological behavior of the PANa / APP hydrogel prepared in Example 1 and the PANa hydrogel prepared in Comparative Example 1; where a is the large-amplitude oscillation scan test of the hydrogel, b is the yield stress value of the hydrogel, c is the frequency scan test of the hydrogel, d is the steady-state shear test of the hydrogel, and e is the inverted behavior of the hydrogel.

[0029] Figure 5 The results show a comparison of the adhesion thickness of the PANa / APP hydrogel prepared in Example 1 and the PANa hydrogel prepared in Comparative Example 1 on the surface of a wooden board.

[0030] Figure 6 Thermogravimetric analysis (TGA) diagrams of the PANa / APP hydrogel prepared in Example 1 and the PANa hydrogel prepared in Comparative Example 1 are shown.

[0031] Figure 7 The flame retardant performance test results of the PANa / APP hydrogel prepared in Example 1 and the PANa hydrogel prepared in Comparative Example 1 on wood board substrate are shown. Detailed Implementation

[0032] To more fully understand and demonstrate the technical solutions, objectives, and advantages of the present invention, the technical effects produced by the present invention will be further described in detail and completely below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. It should be noted that other embodiments obtained by those skilled in the art without departing from the concept of the present invention are all within the protection scope of the present invention.

[0033] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0034] Example 1

[0035] In this embodiment, the flame retardant is APP and the water-absorbing resin is PAna. A PAna / APP composite flame retardant material and a PAna / APP hydrogel are prepared through the following steps:

[0036] PANa and APP (n = 30-50) were dispersed in an ethanol solution at a mass ratio of 2:1 and stirred at 800 rpm at room temperature for 15 min to ensure that PANa and APP were mixed evenly and to obtain a suspension.

[0037] The above suspension was sonicated at 5-15℃ for 30 minutes to obtain a uniformly mixed suspension.

[0038] The above-mentioned uniformly mixed suspension was dried in an oven at 110°C for 8 hours and then pulverized to obtain PANa / APP composite flame retardant material.

[0039] The above PANa / APP composite flame retardant material was dispersed in deionized water and fully swollen to a mass fraction of 3wt% to obtain PANa / APP hydrogel.

[0040] Comparative Example 1

[0041] This comparative example is PANa hydrogel without APP, with a mass fraction of 1 wt%.

[0042] FTIR analysis was performed on the PANa / APP composite flame retardant material prepared in Example 1. The analysis was conducted using an FTIR spectrometer at room temperature, with spectra recorded at 4000–400 cm⁻¹. -1 Within the wavenumber range, it was used for crystal phase identification, and the results were as follows: Figure 1 As shown, the absorption peaks indicate that the PANa / APP composite flame retardant material contains APP.

[0043] The PANa / APP hydrogel prepared in Example 1 was analyzed using SEM-EDS. The sample was scanned at an accelerating voltage of 5 keV, and images were obtained using a secondary electron detector. To prevent charging, a 20 nm gold layer was sputtered onto the sample before morphological analysis. The results are as follows. Figure 2 As shown, N, P, and O elements are clearly covered on the particle surface and are evenly dispersed, indicating that APP is evenly dispersed in the PANa / APP composite flame retardant material.

[0044] Swelling tests were performed on the PANa / APP hydrogel prepared in Example 1 and the PANa hydrogel prepared in Comparative Example 1. 0.1 g of PANa / APP composite flame retardant material powder was weighed and added to deionized water, tap water, and river water, respectively, to swell for at least 5 hours. The mass of a 200-mesh nylon mesh bag was weighed as m2, poured into the 200-mesh nylon mesh bag, and allowed to stand until no water dripped. The mass of the mesh bag and hydrogel was weighed as m3. Each sample was tested in parallel three times, and the average value was taken. The water absorption ratio Q of the resin was calculated according to the following formula. eq :

[0045]

[0046] The results are as follows Figure 3 As shown in the figure, adding APP reduces the swelling ratio of the absorbent resin PANa in the medium.

[0047] The rheological behavior of the PANa / APP hydrogel prepared in Example 1 and the PANa hydrogel prepared in Comparative Example 1 was tested. Different concentrations of PANa / APP hydrogel and PANa hydrogel were prepared, and viscosity-shear rate scans were performed at room temperature using an Anton Paar MCR302 rheometer in the range of 0.001% to 100% shear rate, with ten points every tenfold. The results are as follows. Figure 4As shown.

[0048] from Figure 4 As can be seen from ab, the addition of APP weakens the PANa / APP hydrogel's resistance to external deformation, necessitating the formulation of PANa / APP hydrogels with a higher mass fraction. From Figure 4 c shows that even after adding APP at a mass ratio of 2:1 (PANa to APP), the PANa / APP hydrogel still exhibits solidity, meaning G′ is greater than G″. From Figure 4 As can be seen from d, even after the addition of APP, the PANa / APP hydrogel still exhibits shear-thinning properties and can be applied to spray fire extinguishing. From Figure 4 As can be seen from the above, compared to pure PANa hydrogel, PANa / APP hydrogel with added APP requires a higher mass fraction to resist gravitational factors.

[0049] Spray coating tests were conducted on the PANa / APP hydrogel prepared in Example 1 and the PANa hydrogel prepared in Comparative Example 1. The PANa / APP hydrogel and PANa hydrogel were sprayed onto vertical pine board, concrete, and stainless steel surfaces, respectively, using a spray gun. The hydrogel on the substrate was constantly observed during spraying, and spraying was stopped immediately when the hydrogel showed a tendency to slide off. The thickness of the hydrogel at three points on the substrate was measured using calipers, and the average value was taken. The results are shown below. Figure 5 As shown, although the adhesion performance of the PANa / APP hydrogel is slightly reduced, it can still effectively maintain an adhesion thickness of not less than 5 mm.

[0050] Thermogravimetric analysis (TGA) was performed on the PANa / APP hydrogel prepared in Example 1 and the PANa hydrogel prepared in Comparative Example 1. A Netzsch STA409PC / PG instrument (Netzsch, Germany) was used, with a scanning temperature ranging from 25°C to 600°C and a heating rate of 10°C / min. -1 The flow rate is air, and the result is as follows: Figure 6 As shown, the residual carbon content of the PANa / APP hydrogel increased by 23% at 600℃ after the addition of APP, while the temperature at which the maximum weight loss rate occurred was around 100℃.

[0051] Combustion tests were conducted on the PANa / APP hydrogel prepared in Example 1 and the PANa hydrogel prepared in Comparative Example 1. The PANa / APP hydrogel and PANa hydrogel were respectively coated onto the surface of a 5.08cm × 5.08cm square pine board, with a thickness of approximately 1 / 4 inch. The hydrogel-coated board was vertically fixed approximately 15cm in front of a handheld butane torch for the combustion test. Combustion was stopped when the surface of the board began to char. The results are as follows: Figure 7 As shown, the PANa / APP hydrogel can withstand burning in a butane torch flame at 1800℃ for at least 156 seconds.

[0052] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a hydrogel flame-retardant material with both strong adhesion and high flame retardancy, characterized in that, Includes the following steps: (1) Preparation of suspension: Add water-absorbing resin and flame retardant to ethanol in proportion, stir magnetically first, and then sonicate at low temperature to obtain suspension; (2) Drying and pulverizing: The suspension is dried and pulverized to obtain composite flame retardant material powder; (3) Water absorption and swelling: The composite flame retardant material powder is added to water and fully swelled to obtain the final product.

2. The preparation method of the hydrogel flame-retardant material with both strong adhesion and high flame retardancy according to claim 1, characterized in that, In step (1), the absorbent resin is selected from one or more of sodium polyacrylate, polyacrylamide, and polyacrylonitrile.

3. The method for preparing the hydrogel flame-retardant material with both strong adhesion and high flame retardancy according to claim 1, characterized in that, In step (1), the flame retardant is selected from one or more of ammonium polyphosphate, ammonium phosphate, diammonium hydrogen phosphate, sodium phosphate, disodium hydrogen phosphate, and phytic acid.

4. The method for preparing the hydrogel flame-retardant material with both strong adhesion and high flame retardancy according to claim 1, characterized in that, In step (1), the mass ratio of the water-absorbing resin to the flame retardant is 1-3:1-3.

5. The method for preparing the hydrogel flame-retardant material with both strong adhesion and high flame retardancy according to claim 1, characterized in that, The water-absorbing resin is sodium polyacrylate, and the flame retardant is ammonium polyphosphate, with a mass ratio of 2:

1.

6. The method for preparing the hydrogel flame-retardant material with both strong adhesion and high flame retardancy according to claim 1, characterized in that, In step (1), the magnetic stirring speed is 800 rpm and the magnetic stirring time is 15 min; the low temperature ultrasonic temperature is 5-15℃ and the low temperature ultrasonic time is 30 min.

7. The method for preparing the hydrogel flame-retardant material with both strong adhesion and high flame retardancy according to claim 1, characterized in that, In step (2), the drying conditions include drying at 110°C for 8 hours.

8. The method for preparing the hydrogel flame-retardant material with both strong adhesion and high flame retardancy according to claim 1, characterized in that, In step (3), the mass fraction of the composite flame retardant material powder is 1-17 wt%.

9. A hydrogel flame-retardant material that combines strong adhesion and high-efficiency flame retardancy, characterized in that, The hydrogel flame retardant material with strong adhesion and high flame retardancy as described in any one of claims 1 to 8 is prepared by the method for preparing such material.

10. The application of the hydrogel flame-retardant material with strong adhesion and high flame retardancy as described in claim 9 in hydrogel fire extinguishing agents.

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