A green vegetation near-infrared hyperspectral countermeasure microcapsule camouflage material and a preparation method thereof

Abstract

The application provides a kind of green vegetation near-infrared hyperspectral countermeasure microcapsule camouflage material, which is made of wall material and core material, the wall material is polyurea or polyurea-polystyrene composite layer, and the core material is aqueous liquid.The preparation method is as follows: adding water-soluble diamine monomer into aqueous liquid to adjust the pH value of the system to 8.0 to obtain aqueous liquid core material;adding oil-soluble emulsifier into dichloroethane to obtain oil phase;adding aqueous liquid core material into oil phase to obtain W / O emulsion;adding isocyanate into W / O emulsion, heating to the first polymerization temperature for reaction, adding triethylamine-dichloroethane solution into the reaction solution, heating to the second polymerization temperature for reaction, then cooling, demulsifying, suction filtering, washing, drying to obtain microcapsule camouflage material.The microcapsule camouflage material provided by the application has the same reflection spectrum characteristics as green vegetation near-infrared.

Description

Technical Field

[0001] This invention relates to the field of hyperspectral camouflage materials technology, and in particular to a microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation and its preparation method. Background Technology

[0002] Hyperspectral detection poses a significant challenge to camouflage and stealth technologies. Developing highly weather-resistant biomimetic camouflage materials with fine reflectance spectral characteristics of plant leaves is crucial for solving the camouflage problem under hyperspectral detection. Current green vegetation background camouflage techniques can effectively deceive conventional imaging reconnaissance in the visible and near-infrared regions. However, the fine emission spectral characteristics still differ significantly from the vegetation environment, especially in the near-infrared region, where the reflectance spectra differ considerably from those of green vegetation, making it difficult to effectively counter hyperspectral detection technologies.

[0003] The two reflectance "troughs" near 1450nm and 1930nm in green vegetation are mainly caused by the absorption of water contained in the vegetation. To address this, researchers have employed various methods to introduce water molecules into camouflage materials. Most current camouflage materials introduce bound water using free water, superabsorbent materials as carriers, or hydrated water compounds, such as BaCl2·2H2O and ZnSO4·7H2O, to simulate the reflectance spectrum of plants in the near-infrared region. However, due to the instability of free water, the tendency of superabsorbent materials to expand and change structure, and the high density of hydrated water compounds, existing camouflage materials cannot meet application requirements. An ideal camouflage material should not only have the same green color as vegetation but also possess high water content, high water retention capacity, and suitable density in the near-infrared region.

[0004] Microcapsules possess a core-shell structure, which effectively protects the internal core material. Furthermore, the wall material of the microcapsule does not affect the reflectance spectral characteristics of the core material in the visible-near-infrared region. Qin et al. (Materials Chemistry and Physics, 2012, 136(2-3):737-743) used a water-in-oil emulsion formed from chlorophyll solution and water as the core material and confirmed the feasibility of preparing microcapsules for hyperspectral anti-camouflage through reflectance spectroscopy analysis. However, this literature did not report on its weather resistance. Our weather resistance analysis of the prepared microcapsules revealed poor weather resistance. The reasons for this are as follows: firstly, chlorophyll itself has poor weather resistance; secondly, the water in the microcapsules slowly evaporates at room temperature, and when heated above 100℃, the microcapsules no longer possess the characteristic absorption peak of water, indicating poor water retention. In addition, most of the publicly reported literature on water-soluble core material microcapsules adopts a W / O emulsion system, mainly targeting the encapsulation of water-soluble core materials, and focusing on the sustained-release performance of water-soluble core materials in the fields of medicine and pesticides; a small number of literatures use a W / O / W emulsion system with pure water as the core material, and the microcapsules mainly act as foaming agents. These microcapsules all require the release of water and are not suitable for hyperspectral camouflage applications. Summary of the Invention

[0005] In view of this, the present invention provides a microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation and its preparation method. The present invention encapsulates water into microcapsules using a dense wall material, achieving lightweight, high moisture content, high heat resistance, and high water retention. Furthermore, the microcapsule camouflage material provided by the present invention exhibits a near-infrared reflectance spectrum similarity of 0.95 to that of green vegetation, meaning it possesses near-infrared reflectance spectral characteristics consistent with green vegetation. This makes it a highly promising camouflage material for camouflage in the near-infrared region of green vegetation with fine reflectance spectral characteristics. The preparation process provided by the present invention is simple and suitable for large-scale production applications.

[0006] This invention is achieved through the following technical solution:

[0007] The first objective of this invention is to provide a microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation, which is made of a wall material and a core material. The wall material is a polyurea or a polyurea-polystyrene composite layer, and the core material is an aqueous liquid. The wall material has a mass percentage of 30-60%, and the core material has a mass percentage of 40-70%. The microcapsule camouflage material is a white or green powder with a particle size in the range of 1-100 micrometers.

[0008] Preferably, the aqueous phase liquid comprises 40-90 wt% water and 10-60 wt% water-retaining substance, wherein the water-retaining substance is at least one selected from sorbitol, glycerol, zinc sulfate, and barium chloride.

[0009] Preferably, the visible light reflectance of the polyurea wall material is above 95%.

[0010] Preferably, the polyurea-polystyrene composite layer exhibits only a green reflectance peak in the visible light region.

[0011] Preferably, the visible light transmittance of the aqueous liquid is above 98%.

[0012] The second objective of this invention is to provide a method for preparing microcapsule camouflage materials for near-infrared hyperspectral countermeasures against green vegetation, comprising the following steps:

[0013] (1) Add water-soluble diamine monomer to the aqueous phase liquid, adjust the pH of the system to 8.0, and obtain the aqueous phase liquid core material for later use;

[0014] (2) Add the oil-soluble emulsifier to dichloroethane, stir to obtain the oil phase, and set aside;

[0015] (3) Based on the volume of the aqueous liquid core material, add the aqueous liquid core material to the oil phase. The mass ratio of the aqueous liquid core material to the oil phase is 1:1.5-4. After stirring evenly, a W / O emulsion is obtained.

[0016] (4) Slowly add 60-100wt% diisocyanate-dichloroethane solution to the W / O emulsion, stir at 250-500rpm for 10min, heat to the first polymerization temperature (T1) 15℃-45℃, and react for 30-60min; slowly add 2-5wt% of 10wt% triethylamine-dichloroethane solution to the reaction solution, then heat to the second polymerization temperature (T2) 50℃-80℃, and react for 30-60min; stop heating, allow to cool naturally to room temperature, break the emulsion, filter, wash the filter cake with dichloromethane, and dry at 60℃ to obtain white microcapsule camouflage material.

[0017] The technological advantages of this invention:

[0018] The polyurea wall material of the microcapsules is formed by the reaction of water-soluble amines and isocyanates. Therefore, the formation process involves the migration of two reactive monomers to the interface and the reaction between the two monomers. A preliminary heating reaction (T1) is designed, during which the monomers completely migrate, and the more reactive primary amine groups react with the isocyanate groups to form an outer shell encapsulating the core material, thus initially forming microcapsules. This reaction process is crucial to the microcapsule encapsulation rate. Due to the high reactivity of the primary amine, the temperature of this step should not be too high. Next, a low-concentration triethylamine solution is slowly added, increasing the alkalinity of the emulsion and promoting the reaction of the relatively less reactive secondary amine groups with the isocyanate groups, leading to cross-linking and curing. Finally, the temperature is increased (T2) to ensure the complete reaction of the two monomers, thoroughly forming the microcapsules and further enhancing their mechanical strength and density.

[0019] Preferably, the water-soluble diamine monomer in step (1) is at least one of ethylenediamine, 1,3-propanediamine, diethylenetriamine, and triethylenetetramine.

[0020] Preferably, in step (1), dilute hydrochloric acid is used to adjust the pH value of the system.

[0021] Preferably, the oil-soluble emulsifier in step (2) is at least one of dihydroxystearate (PEG-30), sorbitan trioleate (span 80), sorbitan trioleate (span 80), polyoxyethylene sorbitan trioleate (tween 80), and polydimethylsiloxane, and the proportion of emulsifier in the oil phase is 1-5 wt%.

[0022] Preferably, the stirring speed in step (3) is 3000-5000 rpm and the stirring time is 10-25 min.

[0023] Preferably, in terms of molar amount, the oil-soluble diisocyanate in step (4) is 1.05 to 1.2 times the amount of the water-soluble diamine monomer, and the triethylamine is 0.05 to 0.2 times the amount of the water-soluble diamine monomer. The oil-soluble diisocyanate is any one of 2,4-toluene diisocyanate (TDI), 4,4'-dicyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), and hexamethylene diisocyanate (HDI).

[0024] A further preferred method for preparing a microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation includes the following steps:

[0025] (1) Add green dye and initiator to styrene, stir to obtain green composite wall material solution, and set aside;

[0026] (2) Based on the mass of the white microcapsule camouflage material, the green composite wall material solution is slowly added dropwise to the white microcapsule camouflage material prepared in claim 3. The mixture is shaken to fully wet the surface of the white microcapsule camouflage material. After standing for 30 minutes, a dispersion is obtained for later use.

[0027] (3) Calculate the mass of the dispersion and add it to an aqueous solution of a water-based emulsifier with a mass fraction of 1-6%. Stir to obtain a uniform dispersion emulsion for later use.

[0028] (4) Stir the dispersion emulsion at a speed of 250-500 rpm and heat it to 40-60℃ for 3 hours. Then heat it to 80℃ for 1 hour. Stop heating and let it cool naturally to room temperature. Demulsify, filter, wash the filter cake with deionized water and ethanol, and dry it at 60℃ to obtain green microcapsule camouflage material.

[0029] Preferably, the mass fraction of the green dye in step (1) is 1-40%, the mass fraction of the initiator is 0.5-6%, and the initiator is azobisisobutyronitrile.

[0030] Preferably, the mass ratio of the green composite wall material solution and the white microcapsule camouflage material in step (2) is 1:1-3.

[0031] Preferably, the aqueous emulsifier in step (3) is at least one of sodium dodecyl sulfate, sodium alkenyl sulfonate, sodium succinate monoester sulfonate, polyvinyl alcohol, and gum arabic.

[0032] Preferably, the stirring speed in step (3) is 3000-5000 rpm, and the stirring time is 10-25 min.

[0033] Compared with existing technologies, this invention has the following advantages: This invention encapsulates water into microcapsules using a dense wall material, achieving lightweight, high moisture content, high heat resistance, and high water retention. Furthermore, the microcapsule camouflage material provided by this invention exhibits a near-infrared reflectance spectrum similarity of 0.95 to that of green vegetation, meaning it possesses near-infrared reflectance spectral characteristics consistent with green vegetation. This makes it a highly promising camouflage material for capturing the fine reflectance spectral characteristics of green vegetation in the near-infrared region. The preparation process provided by this invention is simple and suitable for large-scale production applications. Attached Figure Description

[0034] Figure 1 This is a comparison of the infrared reflectance spectrum curves of the white microcapsule camouflage material in Examples 1-3 of this invention and the sycamore tree;

[0035] Figure 2 This is a schematic diagram of the structure of the white microcapsule camouflage material prepared in Examples 1-3 of this invention. Figure 2 In the middle: 1 is the aqueous liquid core material, and 2 is the white polyurea wall material;

[0036] Figure 3 This is a schematic diagram illustrating the preparation process of the white microcapsule camouflage material in Examples 1-3 of this invention;

[0037] Figure 4 These are comparative curves showing the changes in mass over time of the green microcapsule camouflage material of Examples 4-6, the commercially available superabsorbent resin, and the core material of Example 4.

[0038] Figure 5 These are comparative curves showing the change in moisture content over time of the green microcapsule camouflage material of Examples 4-6, the commercially available superabsorbent resin, and the core material of Example 1.

[0039] Figure 6This is a comparison curve of thermogravimetric analysis between the microcapsules of Example 6 of the present invention and commercially available superabsorbent resin;

[0040] Figure 7 This is a comparison of the near-infrared reflectance spectrum curves of the microcapsules of Example 6 of the present invention and the sycamore tree;

[0041] Figure 8 This is a schematic diagram of the structure of the green microcapsule camouflage material prepared in Examples 4-6 of this invention. Figure 8 In the middle: 1 is the aqueous liquid core material, 2 is the white polyurea wall material, and 3 is the green polyurea-polystyrene composite wall material;

[0042] Figure 9 This is a schematic diagram of the preparation process of the green microcapsule camouflage material in Examples 4-6 of the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] Unless otherwise specified, the test methods or experimental methods described in the following examples are all conventional methods; unless otherwise specified, the raw materials and additives are obtained from conventional commercial sources or prepared by conventional methods.

[0045] Example 1

[0046] A method for preparing a microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation, the specific steps of which are as follows:

[0047] (1) Mix 10g of sorbitol aqueous solution with 4g of 1,3-propanediamine water-soluble monomer, adjust the pH of the system to 8.0 with 5g of 37wt% dilute hydrochloric acid, and stir at room temperature until a uniform, clear and transparent solution is formed, i.e., the aqueous phase;

[0048] (2) Add the above aqueous phase to 40g of dichloroethane containing 0.6g of PEG-30, and mechanically stir at 5000rpm for 25min to form a uniform W / O emulsion;

[0049] (3) Reduce the rotation speed to 500 rpm, add 4.2 g HMDI dropwise, continue stirring for 10 min, raise the temperature to the first polymerization temperature of 15 °C, and react for 60 min; slowly add 25 g of 10 wt% triethylamine-dichloroethane solution to the reaction solution, raise the temperature to the second polymerization temperature of 80 °C, react for 30 min, stop heating, and allow to cool naturally to room temperature to terminate the reaction; demulsify, filter, wash the filter cake with DCM, and dry at 60 °C to obtain white microcapsule camouflage material.

[0050] Example 2

[0051] A method for preparing a microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation, the specific steps of which are as follows:

[0052] (1) Mix 10g of zinc sulfate aqueous solution with 4g of diethylenetriamine water-soluble monomer, adjust the pH of the aqueous phase to 8.0 with 7.2g of 37wt% dilute hydrochloric acid, and stir at room temperature until a uniform, clear and transparent solution is formed, i.e., the aqueous phase;

[0053] (2) Add the above aqueous phase to 60g of dichloroethane containing 0.6g PEG-30 and 0.2g Span 80, and mechanically stir at 4000rpm for 25min to form a uniform W / O emulsion;

[0054] (3) Reduce the rotation speed to 300 rpm, add 6.5 g TDI dropwise, continue stirring for 10 min, raise the temperature to the first polymerization temperature of 25 °C, and react for 45 min; slowly add 30 g 10 wt% triethylamine-dichloroethane solution to the reaction solution, raise the temperature to the second polymerization temperature of 70 °C, react for 45 min, stop heating, and allow to cool naturally to room temperature to terminate the reaction; demulsify, filter, wash the filter cake with DCM, and dry at 60 °C to obtain white microcapsule camouflage material.

[0055] Example 3

[0056] A method for preparing a microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation, the specific steps of which are as follows:

[0057] (1) Mix 10g of sorbitol aqueous solution and barium chloride aqueous solution with 1g of 1,3-propanediamine and 3g of ethylenediamine water-soluble monomers, adjust the pH of the aqueous phase to 8.0 with 6.6g of 37wt% dilute hydrochloric acid, and stir at room temperature until a uniform, clear and transparent solution is formed, i.e., the aqueous phase;

[0058] (2) Add the above aqueous phase to 60g of dichloroethane containing 1.0g PEG-30 and 2.0g polydimethylsiloxane, and mechanically stir at 3000rpm for 25min to form a uniform W / O emulsion.

[0059] (3) Reduce the rotation speed to 300 rpm, add 7.5 g HDI dropwise, continue stirring for 10 min, raise the temperature to the first polymerization temperature of 45 °C, and react for 30 min; slowly add 35 g 10 wt% triethylamine-dichloroethane solution to the reaction solution, raise the temperature to the second polymerization temperature of 50 °C, and react for 60 min; stop heating, allow to cool naturally to room temperature, and terminate the reaction; demulsify, filter, wash the filter cake with DCM, and dry at 60 °C to obtain white microcapsule camouflage material.

[0060] Example 4

[0061] A method for preparing a microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation, the specific steps of which are as follows:

[0062] (1) Add 0.2g of green dye and 0.1g of azobisisobutyronitrile to 20g of styrene and stir at room temperature to form a uniform green composite wall material solution for later use;

[0063] (2) Add the green composite wall material solution dropwise to 6.7g of the white microcapsule camouflage material described in Example 1, shake to fully wet the surface of the microcapsule camouflage material, and let it stand for 30 minutes to obtain a dispersion for later use;

[0064] (3) Add the dispersion to 72g of 6% sodium dodecyl sulfate aqueous solution and mechanically stir at 3000rpm for 10min to form a uniform dispersion emulsion for later use.

[0065] (4) Stir the dispersion emulsion at 500 rpm, heat to 40°C and react for 3 hours; then heat to 80°C and react for 1 hour. Stop heating, let it cool naturally to room temperature, break the emulsion, filter, wash the filter cake with deionized water and ethanol, and dry at 60°C to obtain green microcapsule camouflage material.

[0066] Example 5

[0067] A method for preparing a microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation, the specific steps of which are as follows:

[0068] (1) Add 2g of green dye and 0.6g of azobisisobutyronitrile to 20g of styrene and stir at room temperature to form a uniform green composite wall material solution for later use.

[0069] (2) Add the green composite wall material solution dropwise to 15.6g of the white microcapsule camouflage material described in Example 2, shake to fully wet the surface of the microcapsule camouflage material, and let it stand for 30 minutes to obtain a dispersion for later use;

[0070] (3) Add the dispersion to 105g of sodium succinate monoester sulfonate and polyvinyl alcohol aqueous solution with a mass fraction of 3%, and mechanically stir at 4000rpm for 10min to form a uniform dispersion emulsion for later use.

[0071] (4) Stir the dispersion emulsion at 400 rpm, heat it to 50°C and react for 3 hours; then heat it to 80°C and react for 1 hour. Stop heating, let it cool naturally to room temperature, break the emulsion, filter it, wash the filter cake with deionized water and ethanol, and dry it at 60°C to obtain the green microcapsule camouflage material.

[0072] Example 6

[0073] A method for preparing a microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation, the specific steps of which are as follows:

[0074] (1) Add 6g of green dye and 1.0g of azobisisobutyronitrile to 20g of styrene and stir at room temperature to form a uniform green composite wall material solution for later use.

[0075] (2) Add the green composite wall material solution dropwise to 22.5g of the white microcapsule camouflage material described in Example 3, shake to fully wet the surface of the microcapsule camouflage material, and let it stand for 30 minutes to obtain a dispersion for later use;

[0076] (3) Add the dispersion to 200g of 5% sodium succinate monoester sulfonate aqueous solution and mechanically stir at 3000rpm for 10min to form a uniform dispersion emulsion for later use.

[0077] (4) Stir the dispersion emulsion at 300 rpm, heat it to 60°C and react for 3 hours; then heat it to 80°C and react for 1 hour. Stop heating, let it cool naturally to room temperature, break the emulsion, filter it, wash the filter cake with deionized water and ethanol, and dry it at 60°C to obtain the green microcapsule camouflage material.

[0078] The microcapsule camouflage materials prepared in Examples 1-6 were analyzed for moisture content, encapsulation rate, water retention performance, reflectance spectral characteristics, and spectral similarity.

[0079] The testing method is as follows:

[0080] 1. Determination of moisture content and encapsulation rate of microcapsules

[0081] The powder sample of the microcapsules (mass denoted as m1) was dried in a 100℃ oven until its mass remained essentially constant. It was then ground and dried again in a 100℃ oven until a constant weight was achieved, denoted as m2. mt refers to the moisture content of the microcapsules with mass m1 at 100% encapsulation. The moisture content (Cc%) and encapsulation rate (Ec%) of the microcapsules were calculated according to equations (2-1) and (2-2).

[0082]

[0083]

[0084] 2. Analysis of the water retention performance of microcapsules

[0085] Crystalline hydrates and superabsorbent polymers are often used as moisture absorption peaks in biomimetic camouflage materials that mimic green vegetation. Microcapsules, sodium polyacrylate superabsorbent polymers, and core materials with equal water content were placed in a petri dish and placed in an environment of 25°C and 50% relative humidity. The contents were taken out and weighed at regular intervals until the mass was constant. The water retention performance of the materials was evaluated based on the curves of moisture content change over time.

[0086] 3. Analysis of the reflectance spectral characteristics of microcapsules

[0087] The microcapsule powder was placed in a specially designed sample cell, and the reflectance spectral characteristics of the microcapsules were analyzed by a UV-Vis-NIR spectrophotometer with a scanning range of 400-2500 nm.

[0088] 4. Spectral similarity analysis

[0089] The spectral simulation effect of camouflage materials was measured using the standard spectral channels of the U.S. military and the spectral similarity between microcapsules and green vegetation.

[0090] Spectral similarity is generally calculated using the spectral correlation coefficient to quantitatively analyze the spectral simulation effect of microcapsule camouflage materials on green vegetation. The formula for calculating the spectral correlation coefficient is as follows:

[0091]

[0092] Where, x ik x represents the spectral value of the k-th band in the i-th spectral curve; jk This represents the spectral value of the k-th band in the j-th spectral curve; m represents the number of bands. This represents the average value of spectral curve i; The value of spectral curve j represents the average value; r ij This indicates the similarity between two spectral curves, where 0 < r. ij <1, r ij The closer the value is to 1, the higher the similarity between the two spectral lines.

[0093] Test results:

[0094] from Figure 1As can be seen, the microcapsules prepared in Examples 1-3 all exhibit significant moisture absorption peaks at 1450 nm and 1930 nm, with relatively high peak intensities. This is attributed to the stretching vibrations of the OH bonds in the water molecules within the microcapsules. However, the overall reflectivity of the microcapsules is high, resulting in higher positions for both the near-infrared plateau and the moisture absorption peak. Compared to microcapsules with a single core material, the composite core material achieves a regulatory effect, reducing overall reflectivity. The reflectance spectrum in the near-infrared region is essentially consistent with that of green vegetation, with a spectral similarity of up to 94.6% within this band.

[0095] Figure 4 The microcapsules prepared in Examples 4-6 showed very little change in water content, while the commercially available superabsorbent resin (purchased from Yixing Kexin Chemical Co., Ltd.) and core material experienced significant weight loss within 36 hours, indicating obvious water evaporation.

[0096] Figure 5 Both commercially available superabsorbent polymers and core materials exhibited significant water loss within 24 hours, with final moisture contents remaining at approximately 17% and 15%, respectively. Comparison revealed varying water loss rates among different microcapsules, but the overall change rate was less than 3%, primarily due to differences in water adsorption on the surface of the microcapsules.

[0097] Figure 6 Sodium polyacrylate superabsorbent polymer (SAP) loses approximately 80% of its mass below 100°C. Commercially available SAPs exhibit weak moisture protection and poor thermal stability. Microcapsules, on the other hand, maintain essentially the same mass at 100°C but begin to lose weight at 225°C. Although the water inside the microcapsules vaporizes around 116°C, the protective effect of the wall material prevents the water vapor from leaking out until the wall material decomposes at 225°C. This demonstrates that microencapsulation improves the thermal stability of water and provides far superior protection against moisture compared to commercially available SAPs.

[0098] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation, characterized in that, Includes the following steps: (1) Add water-soluble diamine monomer to the aqueous phase liquid, adjust the pH of the system to 8.0, and obtain the aqueous phase liquid core material for later use; (2) Add the oil-soluble emulsifier to dichloroethane, stir to obtain the oil phase, and set aside; (3) Add the aqueous liquid core material to the oil phase. The mass ratio of the aqueous liquid core material to the oil phase is 1:1.5-4. After stirring, a W / O emulsion is obtained. (4) Slowly add 60-100wt% diisocyanate-dichloroethane solution to the W / O emulsion, stir at 250-500rpm for 10min, heat to the first polymerization temperature of 15℃-45℃, and react for 30-60min; slowly add 2-5wt% of 10wt% triethylamine-dichloroethane solution to the reaction solution, heat to the second polymerization temperature of 50℃-80℃, and react for 30-60min; stop heating, cool naturally to room temperature, break the emulsion, filter, wash the filter cake with dichloromethane, and dry at 60℃ to obtain white microcapsule camouflage material; The white microcapsule camouflage material is made of a wall material and a core material. The wall material is polyurea, and the core material is an aqueous liquid. The mass percentage of the wall material is 30-60%, and the mass percentage of the core material is 40-70%. The particle size of the white microcapsule camouflage material is 1-100 micrometers. The aqueous phase liquid comprises 40-90 wt% water and 10-60 wt% water-retaining substance, wherein the water-retaining substance is at least one selected from sorbitol, glycerol, zinc sulfate, and barium chloride. The water-soluble diamine monomer in step (1) is at least one of ethylenediamine, 1,3-propanediamine, diethylenetriamine, and triethylenetetramine; The diisocyanate in step (4) is 1.05 to 1.2 times the amount of water-soluble diamine monomer, and the triethylamine is 0.05 to 0.2 times the amount of water-soluble diamine monomer.

2. The method for preparing the microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation according to claim 1, characterized in that, The oil-soluble emulsifier in step (2) is at least one of dihydroxystearate, sorbitan trioleate, sorbitan trioleate, polyoxyethylene sorbitan trioleate, and polydimethylsiloxane. The emulsifier accounts for 1-5 wt% of the oil phase. The stirring speed in step (3) is 3000-5000 rpm and the stirring time is 10-25 min.

3. The method for preparing the microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation according to claim 1, characterized in that, The diisocyanate, in molar terms, is any one of 2,4-toluene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

4. A method for preparing a microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation, characterized in that, Includes the following steps: (1) Add green dye and initiator to styrene, stir to obtain green composite wall material solution, and set aside; (2) The green composite wall material solution is slowly added dropwise to the white microcapsule camouflage material prepared according to claim 3 to obtain a dispersion for later use; (3) Add the dispersion to an aqueous solution of a water-based emulsifier with a mass fraction of 1-6%, stir to obtain a dispersion emulsion, and set aside for later use; (4) Stir the dispersion emulsion at a speed of 250-500 rpm and heat it to 40-60℃ for 3 hours. Then heat it to 80℃ for 1 hour. Stop heating and let it cool naturally to room temperature. Demulsify, filter, wash the filter cake with deionized water and ethanol, and dry it at 60℃ to obtain green microcapsule camouflage material.

5. The method for preparing the microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation according to claim 4, characterized in that, The mass fraction of the green dye in step (1) is 1-40%, and the mass fraction of the initiator is 0.5-6%, wherein the initiator is azobisisobutyronitrile.

6. The method for preparing the microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation according to claim 4, characterized in that, The mass ratio of the green composite wall material solution and the white microcapsule camouflage material in step (2) is 1:1-3.

7. The method for preparing the microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation according to claim 4, characterized in that, The aqueous emulsifier mentioned in step (3) is at least one of sodium dodecyl sulfate, sodium alkenyl sulfonate, sodium succinate monoester sulfonate, polyvinyl alcohol, and gum arabic.

8. The method for preparing the microcapsule camouflage material for near-infrared hyperspectral countermeasure against green vegetation according to claim 4, characterized in that, The stirring speed in step (3) is 3000-5000 rpm, and the stirring time is 10-25 min.

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