A shelter panel and a method of making the same

Abstract

The application provides a square cabin panel and a preparation method thereof, and belongs to the technical field of square cabin panels.The square cabin panel comprises a surface layer wave-absorbing honeycomb core and a bottom layer wave-absorbing honeycomb core, the surface layer wave-absorbing honeycomb core and the bottom layer wave-absorbing honeycomb core are bonded through high-glue-content prepreg, an impact-resistant skin is arranged on the upper side, a bottom layer skin is arranged on the lower side, the surface layer wave-absorbing honeycomb core and the bottom layer wave-absorbing honeycomb core are bonded with the upper and lower skins through an epoxy adhesive film, a layer of nickel mesh is laid between the bottom layer skin and the epoxy adhesive film, a wave-absorbing coating is sprayed on the surface of the wave-absorbing honeycomb core, and the surface of the bottom layer wave-absorbing honeycomb is sprayed with a periodic wave-absorbing coating through a mask plate shielding mode.The impact-resistant skin, the periodic wave-absorbing honeycomb structure and the nickel mesh layer design solve the compatibility problem of wideband strong wave absorption, light weight and impact resistance of the square cabin panel, the panel has excellent wave-absorbing performance in the range of 1-40GHz, and the panel surface density is not more than 5kg / m 2 , the weight of the square cabin is reduced, and the mobility of ground equipment is improved.

Description

Technical Field

[0001] This invention relates to the field of modular cabin panels, and in particular to a modular cabin panel and its preparation method. Background Technology

[0002] Military containerized units are mobile structures assembled from sandwich panels, designed to carry military equipment and personnel, providing them with the necessary working conditions and environmental protection. Their distinctive shape makes them easily detectable by the enemy. To improve their battlefield survivability, necessary radar stealth measures must be implemented. Furthermore, the containers are subject to impacts during movement; therefore, while meeting stealth requirements, impact resistance must also be considered.

[0003] There are currently three ways to solve the problems of wave absorption performance and impact resistance performance: (1) using a combination of fiberglass and polyurea panels; (2) using high-strength, low-dielectric ultra-high molecular weight PE fiber as a reinforcing material, and combining it with high elongation at break and high elasticity polyurea elastic resin to prepare a low-dielectric, impact-resistant skin as a wave-absorbing material skin; (3) filling the honeycomb pores of the impact-resistant aramid honeycomb core layer with toughening resin. The thickness of polyurea in method 1 needs to be greater than 0.8 mm to achieve impact resistance performance, but when the skin thickness is greater than 0.8 mm, the performance of Ku and Ka bands is poor and cannot achieve broadband strong absorption; although method 2 can achieve broadband strong absorption, the skin prepared by polyethylene / polyurea resin has poor environmental resistance performance and cannot meet the requirements of engineering applications; although method 3 can achieve broadband strong absorption and impact resistance performance, filling the honeycomb pores with resin will result in a large surface density of the honeycomb wave-absorbing material, which cannot meet the requirements of lightweight cabins.

[0004] Currently, achieving strong broadband absorption, especially in the low-frequency band, of the modular container panels mainly involves adding magnetic absorbers. However, adding magnetic absorbers significantly increases the weight of the panels, thereby reducing the mobility of the equipment.

[0005] Chinese patent application CN116834393A discloses a modular housing panel and its preparation method, as well as a modular housing. The modular housing panel includes a first skin layer, a first honeycomb core layer, a second skin layer, a second honeycomb core layer, and a third skin layer stacked sequentially. The first skin layer includes at least one first sub-layer and at least one second sub-layer. The second skin layer includes at least one third sub-layer and at least one fourth sub-layer. The first and third sub-layers are independently selected from at least one of glass fiber reinforced composite material layers and carbon fiber reinforced composite material layers. The second and fourth sub-layers are independently selected from at least one of aramid fiber reinforced composite material layers, PBO fiber layers, PBO reinforced composite material layers, and polyethylene reinforced composite material layers with a molecular weight of 300W or more. While the modular container panels described in this invention offer high cost-effectiveness in ballistic protection, the excessive thickness of the skin layer leads to a significant increase in the reflectivity of the Ku and Ka band panels. Existing technologies also employ fiberglass skins, but fiberglass skins are brittle, and thin, brittle skins are prone to cracking upon impact, resulting in damage to the military modular container panels and failing to meet the requirements of impact applications. Since impact applications are prevalent in military modular container panel engineering, the technical challenge of achieving a compatible solution for both broadband strong wave absorption and impact resistance in modular container panels urgently needs to be addressed. Summary of the Invention

[0006] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a lightweight, broadband, strong absorption, and environmentally resistant honeycomb sandwich cabin panel and its preparation method.

[0007] To achieve the aforementioned objectives, this invention forms a metamaterial structure by designing a certain periodic pattern on the bottom absorbing honeycomb core, which can significantly reduce low-frequency performance without spraying magnetic absorbers. At the same time, it uses nickel mesh to replace the carbon fiber reflective layer, which can significantly reduce the surface density of the container panel while meeting the requirements of the reflective layer. The skin thickness of only 0.3mm can meet the impact resistance index of section 5.1 of GJB2093A-2012 "General Test Methods for Military Containers" - sandwich panel, and at the same time, the skin of this thickness has excellent wave transmission performance.

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

[0009] A modular shelter panel includes, in order of top to bottom, an impact-resistant skin, a surface absorbing honeycomb core, an adhesive layer, a bottom absorbing honeycomb core, a reflective layer, and a bottom skin.

[0010] Preferably, the impact-resistant skin and the bottom skin are made by hot pressing of a prepreg 1 prepared from fiber-reinforced resin, and the resin content in the prepreg 1 is 38%~40%.

[0011] Preferably, the fiber is one of PBO, aramid fiber, or HS glass fiber, and its fiber basis weight is 200~220 g / m². 2 .

[0012] Preferably, the resin is a cyanate ester resin and / or a modified cyanate ester resin, with a dielectric constant (10GHz~40GHz) ε≤3.2 and a dielectric loss (10GHz~40GHz) tanδ≤0.02. At the same time, the resin has excellent flexibility and impact properties, with an impact strength ≥50mm and a flexibility ≤2mm.

[0013] Preferably, the pores of the surface layer absorbing honeycomb core are regular hexagons with a side length of 1.83mm-5.5mm and a thickness of 2mm-12mm.

[0014] Preferably, the holes in the bottom absorbing honeycomb core are regular hexagons with a side length of 1.83mm-5.5mm and a thickness of 2mm-12mm.

[0015] Preferably, the absorbing honeycomb core is one of aramid honeycomb or glass cloth honeycomb.

[0016] More preferably, the bottom absorbing honeycomb core and the bottom absorbing honeycomb core are coated with an absorbing coating.

[0017] More preferably, the bottom absorbing honeycomb core includes multiple periodic honeycomb structural units.

[0018] Preferably, the microwave absorbing coating comprises, by weight, the following components: 0.5-20 parts absorbent, 80-99.5 parts matrix resin, 0.25-10 parts wetting agent, 10-400 parts solvent, 0.5-1 part leveling agent, and 0.2-0.5 parts anti-settling agent.

[0019] Preferably, the absorbent is one or a mixture of several of the following electrical loss absorbents: carbon black, chopped carbon fibers, graphene, carbon nanotubes, etc.

[0020] More preferably, the matrix resin is polyurethane and / or modified polyurethane;

[0021] A further preferred embodiment is the preparation method of the modified polyurethane as follows:

[0022] Under nitrogen atmosphere, diisocyanate and dibutyltin dilaurate were mixed and heated to react. Polyether diol was added and the reaction continued to obtain a prepolymer. Ethylenediamine, sodium [di(2-hydroxyethyl)amino]methanesulfonate and γ-aminoethylaminopropyltrimethoxysilane were added to the prepolymer to react and obtain modified polyurethane.

[0023] By modifying polyurethane, a buffer zone can be formed mechanically to absorb a certain amount of deformation energy, preventing the formation of streaks and cracks, and improving the compatibility between various materials. After curing, chemical bonds are formed and adhered to the continuous phase of polyurethane, further absorbing the deformation energy generated by strain and preventing fracture. This increases the flexibility of the microwave absorbing coating, making it less likely to fall off on the microwave absorbing honeycomb core.

[0024] More preferably, the solvent is water.

[0025] More preferably, the leveling agent is an acrylic copolymer leveling agent and / or a polyester-modified polydimethylsiloxane leveling agent.

[0026] The preparation method of the microwave absorbing coating of the present invention is as follows: the absorber, matrix resin, wetting agent, solvent, leveling agent and anti-settling agent are mixed and stirred evenly to obtain the microwave absorbing coating.

[0027] Furthermore, the surface layer absorbing honeycomb core and the bottom layer absorbing honeycomb core are bonded together with prepreg 2, the fiber cloth weight of the prepreg 2 is 200-220g, and the resin content is 48-52%.

[0028] Furthermore, an epoxy film is provided between the microwave absorbing honeycomb core layer and the impact-resistant skin and the bottom skin.

[0029] More preferably, the reflective layer is a nickel mesh with an areal density of (50~60) g / m². 2 .

[0030] This invention also discloses a method for preparing the above-mentioned modular cabin panels, comprising the following steps:

[0031] S1 First, an absorbing coating is prepared. The surface absorbing honeycomb core is coated with an overall spraying method. The bottom absorbing honeycomb core is coated with an absorbing coating after being shielded by a mask. After surface drying, it is dried and cured to obtain the surface absorbing honeycomb core and the bottom absorbing honeycomb core.

[0032] S2 uses prepreg 1 as the base material and obtains the upper skin and the lower skin by hot pressing;

[0033] S3 is laid up in the following order: impact-resistant skin, epoxy film, surface layer microwave-absorbing honeycomb core, prepreg 2, bottom layer microwave-absorbing honeycomb core, epoxy film, nickel mesh, and bottom layer skin, and then hot-pressed and cured to obtain the cabin panel.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. This invention uses high-strength fiber prepreg as the surface layer, and the skin thickness is only 0.3mm, which can meet the impact resistance performance index of section 5.1 of GJB2093A-2012 "General Test Methods for Military Containers" - sandwich panel. At the same time, the skin of this thickness has excellent wave transmission performance, which can ensure that the container can achieve wideband strong absorption under the frequency band of 1GHz-40GHz.

[0036] 2. In this invention, the surface layer absorbing honeycomb core and the bottom layer honeycomb core are bonded together using a prepreg with a high adhesive content, which reduces the bonding process of epoxy film, prepreg, and epoxy film used in conventional methods, thereby improving production efficiency.

[0037] 3. The bottom-layer absorbing honeycomb core of the present invention, through the mask plate to block the periodic absorbing honeycomb structure design, can significantly improve the low-frequency absorbing performance of the container panel;

[0038] 4. The reflective layer of this invention uses nickel mesh instead of carbon fiber, which reduces the number of molding cycles and also lowers the areal density and cost;

[0039] 5. By modifying the microwave absorbing coating, this invention can enhance the flexibility of the microwave absorbing coating, making it less likely to fall off on the microwave absorbing honeycomb core, thereby improving the mechanical properties of the coating. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the modular cabin structure of Example 1.

[0041] Figure 2 This is a schematic diagram of the mask's structure. Detailed Implementation

[0042] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention.

[0043] Example 1

[0044] A method for preparing a modular shelter panel includes the following steps:

[0045] S1 mixes and stirs 180g of absorbent, 800g of matrix resin, 90g of wetting agent, 3600g of water, 5g of leveling agent, and 0.2g of anti-settling agent evenly to obtain the microwave absorbing coating; wherein the absorbent is carbon black; the wetting agent is polyoxyethylene alkyl aryl ether; the leveling agent is polyester-modified polydimethylsiloxane; and the anti-settling agent is organobentonite;

[0046] The S2 aramid honeycomb core is coated with an overall microwave-absorbing coating and dried and cured at 80°C. The bottom glass cloth honeycomb core is coated with the microwave-absorbing coating after being shielded by a mask. The structural diagram of the mask is shown below. Figure 2 As shown; after surface drying, it is dried and cured at 80℃ to obtain a surface absorbing honeycomb core and a bottom absorbing honeycomb core; the thickness of the surface aramid honeycomb core is 5mm, the core holes are regular hexagonal, and the weight gain of the absorbing coating of the surface aramid honeycomb core is 80g / m². 2 The thickness of the bottom layer of glass cloth honeycomb core is 10mm, and the core holes are regular hexagonal.

[0047] S3 uses prepreg 1 as the base material and is hot-pressed to obtain the upper skin and the lower skin;

[0048] S4 is laid up in the following order: impact-resistant skin, epoxy film, surface aramid honeycomb core, prepreg 2, bottom glass cloth honeycomb core, epoxy film, nickel mesh, and bottom skin. Then, it is placed on a flatbed hot press and hot-pressed to obtain the cabin panel.

[0049] In step S1, the matrix resin is modified polyurethane, which is prepared as follows: Under nitrogen atmosphere, 350g of diisocyanate and 0.5g of dibutyltin dilaurate are mixed and heated to 70°C for 2 hours. Then, 860g of polyether diol is added and the reaction continues for 4 hours to obtain a prepolymer. 12g of ethylenediamine is added to the prepolymer and the reaction continues for 2 hours. 37g of sodium [di(2-hydroxyethyl)amino]methanesulfonate is added dropwise at a rate of 2 drops / second, and the reaction continues for 0.5 hours after the addition is complete. 25g of γ-aminoethylaminopropyltrimethoxysilane is added and the reaction continues for 1 hour. After the reaction is complete, the mixture is cooled to room temperature, and the solvent is removed by evaporation to obtain the modified polyurethane.

[0050] In step S3, the aramid fiber weight of prepreg 1 is 200g and the resin content is 38%.

[0051] In step S4, the glass fiber cloth of prepreg 2 has a basis weight of 210g and a resin content of 50%; the areal density of the nickel mesh is 58g / m². 2 .

[0052] Example 2

[0053] The preparation method is similar to that in Example 1, except that the matrix resin is polyurethane.

[0054] Example 3

[0055] Similar to the preparation method in Example 1, the difference is that the impact-resistant skin and the bottom layer skin are prepared by using a prepreg containing HS glass fiber as the base material and then hot-pressing them.

[0056] Example 4

[0057] Similar to the preparation method in Example 1, except that: the microwave absorbing coating formulation consists of 200g absorbent, 995g matrix resin, 100g wetting agent, 4000g water, 10g leveling agent, and 5g anti-settling agent; the absorbent is graphene; the prepreg 2 has a fiber cloth basis weight of 200g, a resin content of 48%, and a nickel mesh areal density of 50g / m². 2 .

[0058] Example 5

[0059] Similar to the preparation method in Example 1, the difference lies in the following: the microwave absorbing coating formulation consists of 5g absorbent, 800g matrix resin, 2.5g wetting agent, 100g water, 50g leveling agent, and 2g anti-settling agent; the absorbent is carbon nanotubes; the prepreg 2 has a fiber cloth basis weight of 220g, a resin content of 52%, and a nickel mesh areal density of 60g / m². 2 .

[0060] Comparative Example 1

[0061] The difference from Example 1 is that the impact-resistant skin and the bottom skin are prepared by using glass fiber prepreg as the base material and hot pressing them together.

[0062] Comparative Example 2

[0063] The difference from Example 1 is that the bottom absorbing honeycomb core does not have a periodic structure design and is coated by an overall spraying method.

[0064] The modular container panels obtained in the above embodiments and comparative examples were subjected to electrical performance and impact resistance tests. The overall performance of the materials was evaluated through electrical performance and impact resistance tests. The test results are shown in Table 1 below.

[0065] Table 1. Test Results of Container Cabin Panel Performance

[0066]

[0067] The test results show that the embodiments of the present invention meet both the Class I electrical performance requirements of GJB1411A-2015 and the impact resistance requirements of GJB2093-2012. Compared with the comparative example, they have significant advantages in terms of wave absorption performance and impact resistance performance, while the surface density of the wave absorbing plate is no greater than 5 kg / m³. 2 The surface density requirement of the absorbing plate in CN113927984B is significantly lower than that required by CN113927984B. Through the electrical performance and skin design of this method, the requirements of lightweight, wide-band strong absorption and impact resistance can be achieved, and it can be widely applied to various types of military shelters.

[0068] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A modular cabin panel, characterized in that: It includes, in order of top to bottom, an impact-resistant skin, a surface absorbing honeycomb core, an adhesive layer, a bottom absorbing honeycomb core, a nickel mesh, and a bottom skin; The impact-resistant skin and the bottom skin are made by hot pressing of prepreg 1 prepared with fiber-reinforced resin; the fiber is one of PBO, aramid fiber, and HS glass fiber; the resin is cyanate ester resin and / or modified cyanate ester resin. The surface absorbing honeycomb core and the bottom absorbing honeycomb core are coated with a wave-absorbing coating. The surface-layer absorbing honeycomb core and the bottom-layer absorbing honeycomb core are bonded together by an adhesive layer. The raw material of the adhesive layer is prepreg 2, and the fiber fabric weight of the prepreg 2 is 200-220 g / m². 2 The resin content is 48-52%; The microwave absorbing coating comprises, by weight, the following components: 0.5-20 parts absorbent, 80-99.5 parts matrix resin, 0.25-10 parts wetting agent, 10-400 parts solvent, 0.5-1 part leveling agent, and 0.2-0.5 parts anti-settling agent. The matrix resin is a modified polyurethane, which is prepared as follows: under nitrogen conditions, diisocyanate and dibutyltin dilaurate are mixed and heated to react, polyether diol is added, and the reaction is continued to obtain a prepolymer; ethylenediamine, sodium [di(2-hydroxyethyl)amino]methanesulfonate and γ-aminoethylaminopropyltrimethoxysilane are added to the prepolymer to react and obtain the modified polyurethane. The modular cabin panels are mainly produced through the following steps: S1 First, an absorbing coating is prepared. The surface absorbing honeycomb core is coated with an overall spraying method. The bottom absorbing honeycomb core is coated with an absorbing coating after being shielded by a mask. After surface drying, it is dried and cured to obtain the surface absorbing honeycomb core and the bottom absorbing honeycomb core. S2 uses prepreg 1 as the base material and obtains impact-resistant skin and bottom skin after hot pressing; S3 is laid up in the following order: impact-resistant skin, epoxy film, surface absorbing honeycomb core, adhesive layer, bottom absorbing honeycomb core, epoxy film, nickel mesh, and bottom skin, and then hot-pressed and cured to obtain the cabin panel.

2. The modular cabin panel according to claim 1, characterized in that: The surface layer absorbing honeycomb core has hexagonal holes with a side length of 1.83mm-5.5mm and a thickness of 2mm-12mm.

3. The modular cabin panel according to claim 1, characterized in that: The bottom-layer absorbing honeycomb core has hexagonal holes with a side length of 1.83mm-5.5mm and a thickness of 2mm-12mm.

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