High-salt water gel vacuum bag with flame retardant and heat-insulating functions and preparation method thereof

Abstract

A high-salt water gel vacuum bag with flame retardant and heat-insulating functions, with a hydrogel or hydrogel as a sealed shell and a vacuum interior; the hydrogel is made by mixing monomers, initiators, cross-linking agents, saturated salt solutions, and inorganic additives, wherein the inorganic additives account for 0-20% of the weight of the hydrogel. The present invention also provides a preparation method and application of the high-salt water gel vacuum bag. The high-salt water gel vacuum bag of the present invention can effectively isolate the internal and external temperatures, reduce heat transfer, and has many characteristics such as flame retardancy, heat insulation, and thermal insulation. The hydrogel vacuum bag and preparation method provided by the patent of this invention can be applied to flame retardant and heat-insulating materials such as building insulation materials, fire-fighting fireproof clothing, personal protection, military equipment, weapons and equipment, naval, land, air, and space equipment / aerospace engines, military cabins, oil tanks, containers, thermal insulation boxes, and boats.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer flame retardant and heat-insulating materials, and in particular relates to a high-salt water gel vacuum bag with flame retardant and heat-insulating functions and a preparation method thereof. Background Art

[0002] The development of the application industry has put forward higher requirements for flame retardant and thermal insulation new material products, such as lightweight structure, multifunctional composite, and stable performance. The thermal conductivity of the vacuum insulation layer is low, and the thermal conductivity of air is about 0.023Wm -1 K -1 , the thermal conductivity of vacuum is 0.008Wm -1 K -1 , resulting in enhanced vacuum insulation performance. Traditional vacuum insulation layers consist of an inorganic fiber core, protected by a high-gas-barrier composite film shell. However, maintaining this vacuum is difficult, and once the shell is damaged, the material's insulation performance plummets. Currently, there is a lack of vacuum insulation materials that offer excellent insulation, fire resistance, stability, and a long lifespan. Summary of the Invention

[0003] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a high-salt water gel vacuum bag with flame retardant and heat-insulating functions and a preparation method thereof, so as to obtain a vacuum insulation material with flame retardant, high thermal stability, heat insulation and other functions.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A high-salt water gel vacuum bag with flame retardant and heat-insulating functions has a hydrogel or hydrogel as a sealed shell and a vacuum interior; the hydrogel is made by mixing monomers, initiators, cross-linking agents, saturated salt solutions and inorganic additives, wherein the inorganic additives account for 0 to 20% of the weight of the hydrogel.

[0006] In one embodiment, the high-salt water gel vacuum bag with flame retardant and heat-insulating functions of the present invention further includes:

[0007] The support is made of a porous material with heat insulation properties and is filled in the sealed shell.

[0008] In one embodiment, the porous material may be foam metal or foam alloy, or carbide, nitride, boride, or silicide of a refractory metal.

[0009] In one embodiment, the monomer may be one or more of the following: acrylic acid, methacrylic acid, sodium styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate methylammonium chloride, dimethylaminoethyl acrylate methylammonium chloride, diallyldimethylammonium chloride, dimethylaminopropylacrylamidomethylammonium chloride, dimethyldiallylammonium chloride, diallyl-N-carbonylbutoxymethylammonium chloride, diallylmethylbenzylammonium chloride, diallylethylbenzylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, N,N-dimethyl-N-benzyl-acryloyloxyammonium chloride, polyvinyl alcohol, polyethylene glycol, polyethylene oxide, and hyperbranched polyglycidyl ether.

[0010] In one embodiment, the saturated salt solution, the cation can be one or more of the following: sodium ion (Na + ), potassium ion (K + ), lithium ion (Li + ), divalent salt: magnesium ion (Mg 2+ ), calcium ions (Ca 2+ ), iron ions (Fe 3+ ), aluminum salts (Al 3+ ); the anion may be one or more of the following: carbonate (CO3 2- ), sulfate (SO4 2- ), thiosulfate (S2O3 2- ), dihydrogen phosphate (H2PO4 - ), nitrate (NO 3- ), fluoride ion (F - ), chloride ion (Cl - ), bromide ion (Br - ), iodide ion (I - ), perchlorate (ClO4 - ), thiocyanate (SCN - ).

[0011] In one embodiment, the inorganic additive is silica and / or nanoclay.

[0012] In one embodiment, it is characterized in that the polymer in the high-salt water gel is obtained by polymerization reaction of monomers, initiators, and cross-linking agents, the mass ratio of the polymer to the salt content in the saturated salt solution is 1:1 to 1:20, and the weight of the polymer accounts for 1%-50% of the total weight of the hydrogel.

[0013] The present invention also provides a method for preparing the high-salt water gel vacuum bag with flame retardant and heat-insulating functions, comprising the following steps:

[0014] Step 1: Building a mold for preparing an open shell;

[0015] Step 2: Pour a prepolymer solution obtained by uniformly mixing a monomer, an initiator, a cross-linking agent, and a saturated salt solution into the mold, and obtain a hydrogel shell with an opening through polymerization reaction;

[0016] Step 3, vacuuming the hydrogel shell from the opening;

[0017] Step 4: After reaching the vacuum degree, the opening of the hydrogel shell is sealed.

[0018] In one embodiment, the mold includes a trough body and an insert plate. The prepolymer liquid is poured into the trough body, and the insert plate is inserted into the prepolymer liquid in the trough body. The hydrogel obtained after the reaction wraps the insert plate. After the insert plate is pulled out, a hollow shell is obtained. The supports are stacked together and filled into the hollow shell. The hollow shell is cured and sealed, leaving only one opening for vacuuming.

[0019] Compared to existing technologies, this invention utilizes a hydrogel material containing a high-concentration saturated salt solution, or a combination thereof, to create a gel vacuum bag. Upon burning with an open flame in an oxygen-containing environment, the bag produces inorganic metal oxides, exhibiting flame retardancy. Furthermore, upon high-temperature heating in an inert environment, the bag exhibits thermal stability. By maximizing the vacuum level within the bag, the vacuum insulation principle reduces convective and radiative heat transfer, achieving thermal insulation.

[0020] The high-salt water gel vacuum bag with flame retardant and heat-insulating functions described in the present invention can be used as flame retardant and heat-insulating materials such as building insulation layers, fire-fighting clothing interlayers, personal protective clothing interlayers, military equipment flame retardant and heat-insulating interlayers, weapons and equipment flame retardant and heat-insulating protective layers, marine, land, air and space equipment / aircraft engine shell protective layers, military cabin interlayers, oil tank box interlayers, container box interlayers, and thermal insulation box box interlayers. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a mold diagram. The mold consists of a tank body and an insert plate. When in use, the insert plate is inserted into the tank body to form a sealed chamber. (a) is the tank body, and (b) is the insert plate.

[0022] Figure 2 Optical photograph of vacuum-packed PVA / PAA-LiCl hydrogel.

[0023] Figure 3 These are optical photographs of the high saline water gel before and after being heated by an alcohol lamp for 150 seconds, and images of the residue in the flame contact area under SEM.

[0024] Figure 4Figure 2 shows the XRD patterns of the combustion residue, graphites–3R(C)26-1079 and LiClO2 26-1080 in the Jade database after high-salt water gel was flame burned for 2 minutes.

[0025] Figure 5 These are the thermogravimetric (TGA) analysis diagram and differential thermogravimetric (DTG) analysis diagram of high saline water gel.

[0026] Figure 6 Actual photos of the thermal insulation conditions of an insulation bag made of high-salt water gel in vacuum and air conditions. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0028] As mentioned above, existing vacuum insulation devices suffer from fragile outer shells and the inherent flame retardancy of the materials themselves needs improvement. Water, as a common fire extinguisher, is a cheap, readily available, and environmentally friendly flame retardant. Furthermore, due to the polarity and surface tension of water molecules, they adhere to each other and fill gaps, forming a relatively dense liquid layer that can provide a seal to a certain extent. However, water's high fluidity limits its flame retardant and sealing properties in practical applications.

[0029] To this end, the present invention provides a high-salt water hydrogel vacuum bag with flame retardancy and heat insulation properties. Its sealed outer shell is made of hydrogel, and the interior is vacuum-evacuated. Furthermore, unlike existing hydrogels, this hydrogel incorporates a saturated salt solution during its preparation. Specifically, it is primarily made from a mixture of monomers, an initiator, a crosslinker, and a saturated salt solution. Alternatively, it can be further made from a mixture of monomers, initiators, crosslinkers, a saturated salt solution, and inorganic additives.

[0030] The principles of the present invention for achieving flame retardancy, good thermal stability, and heat insulation include the following: hydrogel is a type of polymer material with a three-dimensional network structure that contains a large amount of water. It can absorb a large amount of water and swell while keeping the water from flowing. It can be used as both a flame retardant material and a vacuum sealing material. A large amount of salt is dissolved in the high-salt water gel added to a saturated salt solution. When burned with an open flame in an oxygen-containing environment, inorganic metal oxides are produced, exhibiting flame retardancy; when heated at high temperature in an inert environment, it exhibits thermal stability. Therefore, a gel pack is made using high-salt water gel and de-composite materials, and by maximizing the vacuum degree in the pack, the internal and external temperatures are effectively isolated. Based on the principle of vacuum insulation, convection and radiation heat exchange can be reduced, heat transfer can be reduced, and heat insulation function can be achieved. It has many characteristics such as flame retardancy, heat insulation, and thermal insulation.

[0031] In some embodiments of the present invention, the high-salt water gel vacuum bag further includes a support made of a thermally insulating porous material, such as a metal foam or alloy foam, or a refractory metal carbide, nitride, boride, or silicide. Common examples include bronze foam, stainless steel foam, nickel foam, and titanium foam. The support is filled within the sealed enclosure, further enhancing the thermal insulation and effectively preventing heat transfer.

[0032] In some embodiments of the present invention, the inorganic additive may be a flame-retardant inorganic additive such as silica or nanoclay. The hydrogel with the inorganic additive forms a flame-retardant composite material. The inorganic additive can improve the mechanical properties of the hydrogel composite material and further enhance its flame retardancy.

[0033] The hydrogel contains high concentrations of salt ions, which produce stable and flame-retardant inorganic metal oxides when burned with an open flame in an oxygen-containing environment. The hydrogel itself already has certain flame retardant properties due to the large amount of water it contains. However, the oxides produced by the combustion of the high-salt hydrogel can further effectively block external heat sources, and its flame retardant properties are better than those of ordinary hydrogels. In some embodiments of the present invention, the cations of common high-concentration saturated salt solutions can be selected from one or more monovalent salts, such as sodium ions (Na + ), potassium ion (K + ), lithium ion (Li + ), and one or more divalent salts may be selected or further combined, such as magnesium ion (Mg 2 + ), calcium ions (Ca 2+ ), and one or more trivalent salts may be selected or further combined, such as iron ions (Fe 3+ ), aluminum salts (Al 3 + The anions of the high concentration saturated salt solution can be selected from one or more of the following anions: carbonate (CO3 2- ), sulfate (SO4 2- ), thiosulfate (S2O3 2- ), dihydrogen phosphate (H2PO4 - ), nitrate (NO 3- ), fluoride ion (F - ), chloride ion (Cl - ), bromide ion (Br - ), iodide ion (I - ), perchlorate (ClO4 - ), thiocyanate (SCN - ).

[0034] The high-salt water gel vacuum bag of the present invention uses high-salt water gel as a sealing material to maintain a vacuum environment. The hydrogel used as the sealing material must have good mechanical properties to withstand vacuum pressure. In some embodiments of the present invention, the monomer can be selected from one or more of the following: negatively charged monomers such as acrylic acid (AA), methacrylic acid (MAA), sodium styrene sulfonate (SSS), and 2-acrylamido-2-methylpropanesulfonic acid (AMPS); or positively charged monomers such as dimethylaminoethyl methacrylate methylammonium chloride (DMAEMA·MC), dimethylaminoethyl acrylate methylammonium chloride (DMAEAA·MC), diallyldimethylammonium chloride (DADMAC), dimethylaminopropyl The present invention also provides a kind of alkyl acrylate cross-linking agent, such as methyl acrylate cross-linking agent, alkyl ...

[0035] In some embodiments of the present invention, the polymer obtained by polymerization of monomers, initiators, and crosslinkers in the high-salt water gel has a mass ratio of 1:1 to 1:20 to the salt content of the saturated salt solution. The selection of different dosages is related to the mechanical properties (tensile strength, modulus, etc.), flame retardancy, and thermal stability of the material.

[0036] In some embodiments of the present invention, the total weight of the above-mentioned polymers accounts for 1%-50% of the total weight of the hydrogel.

[0037] In some embodiments of the present invention, the initiator is selected from α-ketoglutaric acid, ammonium persulfate, potassium persulfate, sodium persulfate, 2-hydroxy-2-methyl-1-phenylpropanone, methyl benzoylformate, or an alkyl iodonium salt. Preferably, the initiator is added in an amount of 0.01% to 1% of the total weight of the hydrogel.

[0038] The present invention also provides a method for preparing the high-salt water gel vacuum bag having flame retardant and heat-insulating functions, wherein a hydrogel containing a high-concentration saturated salt solution or a composite thereof is used as a sealed shell, and vacuuming is performed to obtain the high-salt water gel vacuum bag, which specifically comprises the following steps:

[0039] Step 1: Build a mold for preparing an open shell.

[0040] In this step, the mold can be any form that can produce an open shell, with the size and shape selected based on the application. The mold material can be selected from commonly used mold materials such as plastic, glass, and stainless steel. The appropriate mold material is selected based on the type of hydrogel. For example, the mold primarily consists of two main parts: a trough body and an insert plate.

[0041] In step 2, the prepolymer liquid obtained by uniformly mixing the monomer, initiator, cross-linking agent and saturated salt solution is poured into the mold, and a hydrogel shell with an opening is obtained through polymerization reaction. It should be noted that when there is a support, the supports can be stacked together and filled into the shell. According to the above example, the prepolymer liquid is poured into the tank body, and the insert plate is inserted into the prepolymer liquid in the tank body. The hydrogel obtained after the reaction wraps the insert plate, and then the insert plate is pulled out to obtain a hollow shell. One end of the hollow shell is open, and the open end is cured and sealed, leaving only the opening for vacuuming, that is, the hydrogel shell with an opening. Obviously, when necessary, the supports can be stacked together and filled into the hollow shell before curing and sealing.

[0042] The polymerization reaction in this step can be initiated by light, heat or radiation.

[0043] Step 3: vacuum the hydrogel shell from the opening.

[0044] In this step, vacuuming can reduce the internal pressure to about -0.09 MPa.

[0045] Step 4: After reaching the vacuum degree, the opening of the hydrogel shell is sealed.

[0046] The sealing treatment in this step can be performed by using chemical adhesives for quick sealing, wherein the chemical adhesives are selected from acrylic modified epoxy adhesive or epoxy adhesive, phosphate adhesive, dental putty, α-cyanoacrylate instant glue, acrylic diester anaerobic glue and other reaction curing adhesives or UV light curing gels.

[0047] In a more specific embodiment of the present invention, the method for preparing a high saline gel vacuum bag is as follows:

[0048] The first step is to prepare a mold for the hydrogel opening shell, such as Figure 1 First, use 8mm thick silicone as a spacer to form a 10×10×0.2cm 3 Then, use the laser cutting machine to cut out rectangular acrylic sheets (9.8×9.2×0.4cm 3 ) and suspended it between two glass plates. The distance between both sides of the acrylic sheet and the glass surface was 0.2 cm. The distance between the bottom of the acrylic sheet and the silicone gasket was fixed at 0.2 cm.

[0049] Step 2: Used to prepare a high-salt water gel with an open shell for hydrogel. First, dissolve 3g of polyvinyl alcohol in 70mL of deionized water under 90°C water bath conditions, then add 15g of diallylmethylbenzyl ammonium chloride, and add 38.41g of LiCl and dissolve evenly at room temperature at 37°C. The mass ratio of polyvinyl alcohol powder to diallylmethylbenzyl ammonium chloride is 1:3, deionized water accounts for 30% of the total mass of the mixed solution, and the amount of initiator alkyl iodonium salt added accounts for 0.05% of the total weight of the hydrogel. Pour the prepared solution into the specific mold designed by the first step, let it stand at room temperature for 12 hours to completely defoam, and then place it under ultraviolet light for 6 hours. Finally, a high-salt water gel (9.8×9.6×0.8cm 3 Finally, the acrylic sheet is directly pulled out to obtain the hollow gel pack.

[0050] Step 3: Prepare the high saline gel vacuum bag. First, place two layers of flat nickel foam (9×9×0.4cm 3 , porosity 98%) are stacked together as spacer supports in the gel pack. Then, an infusion tube (inner diameter 0.8mm) is inserted into the bottom of the gel pack along the inner edge. Next, an acrylic adhesive is applied to the opening of the gel pack, which is cured and seals the entire gel pack. Finally, the injection tube is connected to the vacuum pump and vacuum gauge through a three-way valve. After the vacuum pump is started for 3 minutes, the pressure in the gel pack drops to -0.09MPa. Afterwards, by replacing the three-way valve, only the vacuum gauge and the gel pack are connected, and the pressure gauge value is observed and recorded. After 24 hours, it was found that the vacuum degree in the gel pack was stable. Finally, a high-salt water gel vacuum bag with flame retardancy, high thermal stability and heat insulation functions was obtained, such as Figure 2 .

[0051] In order to verify and study the flame retardancy of the high-salt water gel obtained in the above example and its cause, the high-salt water gel was placed in the center of a ring frame (inner diameter 5.2 mm) and burned with an alcohol lamp while keeping the gel flame retardant film at the outer edge of the flame (the flame temperature reached 840-850°C). Figure 3 . A small piece of 0.5g butter is supported on the top of the gel layer, and the gel layer can keep the butter cube from being completely melted within 150s. After burning the gel layer with an open flame for 150s, the black crystals formed after the gel in the flame contact area was burnt can be directly observed with the naked eye. At the same time, white crystals containing similar inorganic salts are produced in this area. The high-salt water gel exhibits flame retardant properties. In order to further study the reasons for the flame retardancy, the surface structure of the gel sample in the flame contact area was observed under a scanning electron microscope (SEM), and it can be observed that the white solid substance is a substance showing a porous state.

[0052] In order to explore the types of crystals in the gel after burning, the gel samples in the flame contact area were subjected to XRD analysis, such as Figure 4 As shown in the figure, the main peaks of this solid substance closely match those of graphites–3R(C) 26-1079 and LiClO2 26-1080 in the Jade database. This indicates that the main residual substances after combustion are carbon and LiClO2. LiClO2 is an inorganic oxide that is deliquescent and non-flammable. Since a large amount of LiCl salt is dissolved in the high-salt gel, the flame retardancy of the high-salt gel is attributed to the formation of this inorganic metal oxide.

[0053] The thermal stability of high saline gel samples was characterized, e.g. Figure 5 As shown in Figure 1, argon atmosphere was used for TGA / DTG thermal analysis because the LiClO2 generated by direct combustion of samples in air is highly sensitive to oxygen. The TGA thermogravimetric curve records the percentage of mass retained (m / %) as a function of temperature. The DTG differential thermogravimetric curve records the rate of mass change (dm / dt) as a function of temperature. The downward axis of the TG curve represents sample weight loss (mass loss). The experimental results show that the high-salt water gel has four primary degradation temperatures (134°C, 284°C, 379°C, and 439°C). Below 200°C, the degradation of the high-salt water gel begins with water loss. Because the samples contain a certain amount of free water, the first peak in both samples is attributed to the release of water molecules. The final hydrogel release amount is 30 wt%. The mass loss reaction occurring around 284°C is believed to be due to dehydration and decarboxylation, resulting in the formation of intermolecular and intramolecular anhydrides within the polymer. The third decomposition stage, occurring around 379°C and 373°C, is the result of residual polymer degradation. The mass loss reaction occurring around 439°C is due to the breakage of CH and CO bonds in the material. The mass loss reaction occurring around 719°C is caused by the decomposition of CC bonds. The TGA results above indicate that the high-salt water gel has strong thermal stability.

[0054] The present invention uses high-salt water gel as vacuum sealing material and fills it with foam nickel mesh material as the skeleton, and then makes a high-salt water gel vacuum bag through vacuum packaging. If the vacuum degree is difficult to maintain or it is damaged, the thermal insulation performance of the material will drop sharply. Figure 6 During the experiment, the gel pack can maintain a vacuum state (pressure of about -0.08MPa) quite stably for more than 12 hours, which shows that high-salt water gel can be used as a vacuum sealing material.

[0055] The present invention is based on the principle of vacuum insulation, and reduces convection and radiation heat transfer by maximizing the vacuum degree in the gel pack. The present invention heats a high-salt water gel vacuum pack and a non-vacuumed gel pack with an alcohol burner, and compares the thermal insulation performance of the gel pack before and after vacuuming. Figure 6First, a layer of high salt water gel flame retardant film (65×65×1mm 3 ) and a high-salt water gel pack were placed on a ring stand (inner diameter 5.2mm) in sequence. Then, a 0.5g butter block was placed on top of each gel pack. Finally, an alcohol burner was placed in the center of the ring stand, and the height of the ring stand was adjusted so that the PVA / PAA-LiCl gel flame retardant film at the bottom was at the edge of the flame (the outer flame temperature was measured by a thermocouple at 840-850°C, Ni / Cr was the anode, and Ni / Si was the cathode). The time it took for the butter block to completely melt was recorded. The results showed that it took 150 seconds for the butter block to completely melt in the vacuum state of the high-salt water gel pack, and its thermal insulation effect was significantly better than the result of the butter block melting in 90 seconds in the air state. This shows that vacuum insulation materials made of high-salt water gel have the advantages of excellent thermal insulation effect, fire resistance and non-combustibility, good compressive and tensile strength, good product stability, and long life.

[0056] The hydrogel vacuum bag and preparation method provided by the present invention can be applied to flame-retardant and heat-insulating materials such as building insulation materials, fire-fighting clothing, personal protection, military equipment, weaponry, naval, land, air and space equipment / aerospace engines, military cabins, oil tanks, containers, thermal insulation boxes, and boats.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high salt water gel vacuum bag with flame retardant and heat insulation functions, characterized in that: The invention comprises a support and a hydrogel as a sealed shell with a vacuum inside; the support is made of a porous material with heat insulation properties and is filled in the sealed shell; the hydrogel is made by mixing monomers, initiators, cross-linking agents, saturated salt solutions and inorganic additives, wherein the inorganic additives account for 0-20% of the weight of the hydrogel.

2. The high salt water gel vacuum bag with flame retardant and heat insulating functions according to claim 1, characterized in that: The porous material is foam metal or foam alloy, or carbide, nitride, boride or silicide of refractory metal.

3. The high salt water gel vacuum bag with flame retardant and heat insulating functions according to claim 1, characterized in that: The monomer is one or more of the following: acrylic acid, methacrylic acid, sodium styrene sulfonate, 2-acrylamido-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate methylammonium chloride, dimethylaminoethyl acrylate methylammonium chloride, diallyldimethylammonium chloride, dimethylaminopropylacrylamidomethylammonium chloride, diallyl-N-carbonylbutoxymethylammonium chloride, diallylmethylbenzylammonium chloride, diallylethylbenzylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, and N,N-dimethyl-N-benzyl-acryloyloxyammonium chloride.

4. The high salt water gel vacuum bag with flame retardant and heat insulating functions according to claim 1, characterized in that: The saturated salt solution, the cation is one or more of the following: sodium ion (Na + ), potassium ion (K + ), lithium ion (Li + ), magnesium ions (Mg 2+ ), calcium ions (Ca 2+ ), iron ions (Fe 3+ ), aluminum salts (Al 3+ ); anion is one or more of the following: carbonate (CO3 2- ), sulfate (SO4 2- ), thiosulfate (S2O3 2- ), dihydrogen phosphate (H2PO4 - ), fluoride ion (F - ), chloride ion (Cl - ), bromide ion (Br - ), iodide ion (I - ), thiocyanate (SCN - ).

5. The high salt water gel vacuum bag with flame retardant and heat insulating functions according to claim 1, characterized in that: The inorganic additive is silicon dioxide and / or nanoclay.

6. The high salt water gel vacuum bag with flame retardant and heat insulating functions according to any one of claims 1 to 5, characterized in that: The high-salt water gel is obtained by polymerization of monomers, initiators, and crosslinking agents. The mass ratio of the polymer to the salt content in the saturated salt solution is 1:1-1:20, and the weight of the polymer accounts for 1%-50% of the total weight of the hydrogel.

7. The method for preparing the high salt water gel vacuum bag with flame retardant and heat insulating functions according to any one of claims 1 to 6, characterized in that: The steps include: Step 1: Building a mold for preparing an open shell; Step 2: Pour the prepolymer solution obtained by uniformly mixing the monomer, initiator, cross-linking agent and saturated salt solution into the mold, and obtain a hydrogel shell with an opening through polymerization reaction. The mold includes a tank body and an insert plate. Step 2 is specifically as follows: The prepolymer liquid is poured into the tank, and the insert is inserted into the prepolymer liquid in the tank. The hydrogel obtained after the reaction wraps the insert; after the insert is pulled out, a hollow shell is obtained, and the supports are stacked together to fill the hollow shell, and the hollow shell is cured and sealed, leaving only the opening for vacuuming. Step 3, vacuuming the hydrogel shell from the opening; Step 4: After reaching the vacuum degree, the opening of the hydrogel shell is sealed.

8. Application of the high salt water gel vacuum bag with flame retardant and heat insulating functions according to any one of claims 1 to 6 as a building insulation layer, a fire-fighting clothing interlayer, a personal protective clothing interlayer, a flame retardant and heat insulating interlayer for military equipment, a flame retardant and heat insulating protective layer for weapons and equipment, a protective layer for the outer shell of naval, land, air and space equipment / aerospace engines, a military cabin interlayer, an oil tank box interlayer, a container box interlayer, and an insulation box box interlayer.

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