Plant leaf imitating camouflage material and preparation method thereof

Abstract

The invention belongs to the technical field of engineering camouflage, and relates to a plant leaf imitating camouflage material and a preparation method thereof. The preparation method comprises the following steps: firstly, respectively preparing a fiber structure layer, a water sealing layer and a chlorophyll protection layer, then laying the fiber structure layer, the water sealing layer, the chlorophyll protection layer and a waterproof layer from bottom to top to obtain a prefabricated body, and finally gluing and compounding the prefabricated body to obtain the plant leaf imitating camouflage material. The camouflage material adopts the four-layer composite structure, so that the plant leaf imitating camouflage material has spectral characteristics similar to that of plant leaves, and vegetation camouflage is realized; in addition, the plant leaf imitating camouflage material does not have the problems of fallen leaves and withering, so that the camouflage effect is more durable.

Description

Technical Field

[0001] The present invention belongs to the technical field of engineering camouflage, relates to bionic composite materials, and particularly relates to a plant leaf-like camouflage material and a preparation method thereof. Background Art

[0002] Vegetation camouflage achieves target concealment by constructing a natural ecological barrier. Traditional vegetation camouflage uses natural vegetation such as sowing, transplanting, and collecting to cover or conceal the target. It has three main advantages: First, after camouflage, it can have the same appearance and characteristics as the surrounding background, and when the vegetation has a certain density, it can effectively deal with optical, thermal infrared, and radar reconnaissance; Second, when transplanting vegetation to conceal the target, the camouflage effect can be obtained immediately and no special maintenance is required; Third, after camouflage, it can not only green the environment but also widely camouflage the target. However, using natural vegetation for camouflage also has certain disadvantages: First, after the vegetation loses its leaves, the camouflage effect is reduced; Second, sowing or planting vegetation requires a certain amount of manpower and time; Third, the collected vegetation is prone to drying out, the effect is not lasting, and it needs to be replaced frequently, which is only suitable for temporary camouflage.

[0003] In view of this, the present invention is specifically proposed. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art and provide a plant leaf-like camouflage material and a preparation method thereof, so as to solve the problems in the prior art that the camouflage effect is reduced due to the fallen leaves or drying of natural vegetation and the camouflage effect is not lasting.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] On the one hand, the present invention provides a preparation method of a plant leaf-like camouflage material. First, a fiber structure layer, a water sealing layer, and a chlorophyll protection layer are respectively prepared, and then the fiber structure layer, the water sealing layer, the chlorophyll protection layer, and a waterproof layer are stacked in order from bottom to top to obtain a preform, and finally the preform is adhesively compounded to obtain the plant leaf-like camouflage material.

[0007] Further, the preparation method specifically includes the following steps:

[0008] Step 1, prepare the fiber structure layer: construct a fiber structure layer from a loose and porous fiber material by using a specific process;

[0009] Step 2, prepare the water sealing layer: based on the prepared high-barrier packaging bag, first add distilled water into the high-barrier packaging bag to discharge the air in the high-barrier packaging bag, and then seal the high-barrier packaging bag to obtain the water sealing layer;

[0010] Step 3: Prepare the chlorophyll protection layer: Prepare the chlorophyll extraction solution and the polymer aqueous solution respectively. Mix the chlorophyll extraction solution and the polymer aqueous solution evenly according to the mass ratio of 1:(10-20), pour the mixture into a mold, and obtain the chlorophyll protection layer after coating and drying.

[0011] Step 4: Prepare the plant leaf-like camouflage material: Stack the fiber structure layer, the water sealing layer, the chlorophyll protection layer and the waterproof layer in sequence from bottom to top to obtain a preform, and perform adhesive bonding on the preform to obtain the plant leaf-like camouflage material.

[0012] Further, Step 1 specifically includes:

[0013] Step 1.1: Clean the surface of the glass slide, and use the treated glass slide as a substrate for standby.

[0014] Step 1.2: Prepare a reaction solution by the direct dissolution method, and coat the reaction solution on the surface of the substrate through a high-speed rotary coating process to obtain a porous fiber material.

[0015] Step 1.3: Peel the porous fiber material from the substrate to obtain the fiber structure layer.

[0016] Even further, Step 1.2 specifically includes:

[0017] Step 1.2.1: Add the cellulose raw material to the first solvent, control the stirring speed at 200-500 r / min, the temperature at 80-120 °C, and the stirring time at 2-5 h until the cellulose raw material is completely dissolved to obtain a uniform fiber solution.

[0018] Step 1.2.2: Add the pore-forming agent to the fiber solution, control the stirring speed at 100-300 r / min, and the stirring time at 0.5-1 h, and stir evenly to obtain a mixed solution.

[0019] Step 1.2.3: Add a cross-linking agent and a catalyst to the mixed solution, control the reaction temperature at 40-60 °C, and the cross-linking reaction time at 2-4 h, and obtain a reaction solution after the cross-linking reaction.

[0020] Step 1.2.4: After dropping the reaction solution at the center of the substrate, fix the substrate on a rotary coater, and form a uniform liquid film on the surface of the substrate through a high-speed rotary coating process.

[0021] Step 1.2.5: Place the substrate coated with the liquid film in a drying device, control the drying temperature at 50-90 °C, and the curing time at 5-10 h, and obtain a porous fiber material after the drying and curing are completed.

[0022] Specifically, in step 1.2.2, the added mass of the pore-forming agent is 20% to 50% of the cellulose raw material.

[0023] Specifically, in step 1.2.3, the added mass of the cross-linking agent is 5% to 15% of the mass of the cellulose raw material, and the added mass of the catalyst is 3% to 7% of the mass of the cellulose raw material.

[0024] Specifically, the cellulose raw material is selected from one of cotton fiber or wood pulp fiber; the first solvent is selected from one of N-methylpyrrolidone, N,N-dimethylformamide, N-methylmorpholine-N-oxide or 1-butyl-3-methylimidazolium chloride;

[0025] The pore-forming agent is selected from one of sodium chloride, ammonium bicarbonate, sucrose or glucose, and the added amount of the pore-forming agent is 20% to 50% of the mass of the cellulose raw material;

[0026] The cross-linking agent is one of glutaraldehyde or formaldehyde, and the catalyst is one of hydrochloric acid or sulfuric acid; the added amount of the cross-linking agent is 5% to 15% of the mass of the cellulose raw material, and the added amount of the catalyst is 3% to 7% of the mass of the cellulose raw material;

[0027] The process of high-speed rotary coating is as follows: first, spin-coat at a low speed of 30 to 50 r / s for 10 to 20 s, and then accelerate to 750 to 1000 r / s at an acceleration of 500 r / s and continue to spin-coat for 10 to 20 s.

[0028] Further, in step 2, the preparation process of the high-barrier packaging bag is as follows:

[0029] Step 2.1: Mix the dried polyvinylidene fluoride, modifier and plasticizer according to a preset mass ratio, and after stirring evenly, obtain a mixed material; wherein, the mass ratio of the polyvinylidene fluoride, the modifier and the plasticizer is 100:(5 to 20):(10 to 30);

[0030] Step 2.2: Add the mixed material into a twin-screw extruder for melt blending and extrusion into pellets, and air-cool and pelletize the extruded pellets to obtain modified polyvinylidene fluoride pellets;

[0031] Step 2.3: Add the modified polyvinylidene fluoride pellets into the hopper of a blown film machine and blow them into a film to obtain a modified polyvinylidene fluoride film;

[0032] Step 2.4: Cut the modified polyvinylidene fluoride film according to the design requirements to obtain film sheets;

[0033] Step 2.5: Heat-seal the film sheets through a heat-sealing machine to obtain a high-barrier packaging bag.

[0034] Specifically, the modifier is selected from one of rice clay, graphene or carbon nanotubes;

[0035] The plasticizer is one of phthalate esters, aliphatic dibasic acid esters or phosphate esters; Preferably, the phthalate esters are dibutyl phthalate or dioctyl phthalate, the aliphatic dibasic acid esters are dibutyl sebacate or dioctyl adipate, and the phosphate esters are triphenyl phosphate or tricresyl phosphate;

[0036] The extrusion temperature of the extruded granules is 180 - 250 °C, and the screw speed is 100 - 300 r / min; The process parameters for heat sealing are: the heat sealing temperature is 150 - 180 °C, the heat sealing time is 1 - 3 s, and the heat sealing pressure is 0.2 - 0.5 MPa.

[0037] Furthermore, the preparation process of the chlorophyll extract in step 3 is as follows:

[0038] Wash the plant leaves clean with distilled water, blot the water on the surface of the washed plant leaves with filter paper, and then cut the plant leaves with the surface water blotted into leaf pieces of 1 - 2 cm 2 in size;

[0039] Mix the leaf pieces and the organic solvent in a volume ratio of 1:(10 - 20), and then place them at room temperature for 12 - 24 h to ensure the dissolution of chlorophyll in the leaf pieces, obtaining a chlorophyll solution;

[0040] Perform solid - liquid separation on the chlorophyll solution by filtration method, and collect the separated supernatant as the chlorophyll extract.

[0041] Specifically, the organic solvent is selected from any one of acetone, ethanol, ether, acetone - ether or methanol - petroleum ether.

[0042] Among them, the preparation process of the polymer aqueous solution in step 3 is as follows:

[0043] Add PVA monomer to distilled water, stir at a temperature of 80 - 90 °C until the PVA monomer is completely dissolved, and prepare a PVA solution with a mass fraction of 5% - 10%.

[0044] In addition, the present invention also provides a plant - leaf - like camouflage material prepared by the above - described preparation method in part or in whole. The reflectivity of the surface of the plant - leaf - like camouflage material is 40% - 60%, and it has the "near - infrared plateau" characteristic of green plants in the wavelength range of 780 - 1300 nm.

[0045] Specifically, the plant leaf - mimicking camouflage material includes: a fiber structure layer, a water - sealing layer, a chlorophyll protection layer, and a waterproof layer, which are arranged in sequence from bottom to top, and the adjacent layers are bonded and fixed by polyurethane glue; among them,

[0046] The fiber structure layer is a loose and porous structure, which is used to simulate the mesophyll tissue of plant leaves; the water - sealing layer is used to provide the water absorption characteristics of plant leaves and prevent water from evaporating and dissipating; the chlorophyll protection layer is used to make the camouflage material have a similar appearance color to plant leaves; the waterproof layer is used to provide waterproof performance, which can solve the problem of poor water - resistance of the chlorophyll protection layer and improve the overall weather resistance of the plant leaf - mimicking camouflage material.

[0047] Specifically, the waterproof layer is selected from one of polyvinyl alcohol (PVA) waterproof film, polyurethane (PU) waterproof film, or polyvinylidene chloride (PVDC) waterproof film. It should be noted that the polyvinyl alcohol waterproof film is a waterproof film made by a modification process (such as adding waterproof agents, cross - linkers, fillers, etc.) on the basis of polyvinyl alcohol (PVA). For example, by adding cross - linkers (such as aldehydes, citric acid, etc.), a three - dimensional network structure can be formed to reduce hydrophilicity; it can be laminated with other hydrophobic materials (such as PE, PP) to form a multi - layer structure; hydrophobic materials such as silicone can be coated to isolate water from contacting the PVA substrate to achieve the purpose of waterproofing.

[0048] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0049] 1) The fiber structure layer is used to simulate the mesophyll tissue of plant leaves. It is a loose and porous structure, which can make light refract multiple times inside the plant leaf - mimicking camouflage material and then return to its upper surface and be emitted. In this way, a high reflectivity of 40% - 60% can be formed on the surface of the plant leaf - mimicking camouflage material, and the "near - infrared plateau" characteristic of green plants can be obtained in the wavelength range of 780 - 1300 nm;

[0050] 2) The chlorophyll protection layer makes the camouflage material have a similar appearance color to plant leaves, and the overall reflectivity of the reflection spectrum of the plant leaf - mimicking camouflage material in the visible light band is relatively low. By encapsulating chlorophyll in an organic film layer with high oxygen - barrier properties, the light stability of the chlorophyll protection layer can be improved, avoiding the problem of visible light camouflage failure caused by the photodegradation of chlorophyll;

[0051] 3) Since water is the main determinant in the short - wave infrared band after 1300 nm, the present invention can provide the water absorption characteristics of plant leaves through the water - sealing layer, prevent water from evaporating and dissipating, and make the reflection spectrum of the camouflage material show two obvious water absorption valleys at 1440 nm and 1920 nm in the short - wave infrared band;

[0052] 4) The waterproof layer can solve the problem of poor water resistance of the chlorophyll protection layer and improve the overall weather resistance of the plant leaf-like camouflage material.

[0053] In summary, through the above four-layer composite, the plant leaf-like camouflage material of the present invention can have spectral characteristics similar to those of plant leaves, thereby achieving vegetation camouflage. Moreover, since there are no problems of fallen leaves and withering for the plant leaf-like camouflage material, the camouflage effect is more lasting. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The drawings here are incorporated into the specification and form a part of this specification, and are used together with the specification to explain the principles of the present invention.

[0055] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0056] Figure 1 is a flowchart of the preparation method of the plant leaf-like camouflage material provided by the present invention;

[0057] Figure 2 is a schematic structural diagram of the plant leaf-like camouflage material provided by the present invention;

[0058] Figure 3 is a near-infrared plateau test curve graph of the plant leaf-like camouflage materials prepared in Embodiments 1 to 6 provided by the present invention.

[0059] Wherein: 1. Fiber structure layer; 2. Water sealing layer; 3. Chlorophyll protection layer; 4. Waterproof layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0060] Here, the exemplary embodiments will be described in detail. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the present invention. On the contrary, they are only examples consistent with some aspects of the present invention detailed in the appended claims.

[0061] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the drawings and embodiments.

[0062] Embodiment 1

[0063] See Figure 1 , this embodiment provides a preparation method of a plant leaf-like camouflage material, which specifically includes the following steps:

[0064] Step 1, preparing the fiber structure layer 1:

[0065] Step 1.1: Clean the surface of the glass slide, and use the processed glass slide as a substrate for standby; specifically, the surface of the glass slide can be wiped with anhydrous ethanol for 5 times to remove the pollutants attached to the surface of the glass slide, obtaining a glass slide with a clean surface, and use this glass slide as a substrate for standby;

[0066] Step 1.2: Prepare a reaction solution by the direct dissolution method, and coat the reaction solution on the surface of the substrate through a high-speed rotary coating process to obtain a loose and porous fiber material; specifically, it includes:

[0067] Step 1.2.1: Add cotton fibers into N-methylpyrrolidone, control the stirring speed at 200 r / min, the temperature at 80 °C, and the stirring time at 5 h until the cotton fibers are dissolved to obtain a uniform fiber solution;

[0068] Step 1.2.2: Add sodium chloride into the fiber solution, control the stirring speed at 100 r / min, and the stirring time at 1 h, and obtain a mixed solution after stirring evenly;

[0069] Step 1.2.3: Add glutaraldehyde and hydrochloric acid into the mixed solution, control the reaction temperature at 40 °C, and the cross-linking reaction time at 4 h, and obtain a reaction solution after cross-linking reaction; wherein, the addition amount of sodium chloride is 20% of the mass of the cotton fibers, the addition amount of glutaraldehyde is 5% of the mass of the cotton fibers, and the addition amount of hydrochloric acid is 3% of the mass of the cotton fibers;

[0070] Step 1.2.4: Drop the reaction solution onto the center of the substrate, then fix the substrate on a rotary coater, and form a uniform liquid film on the surface of the substrate through a high-speed rotary coating process; wherein, the process of high-speed rotary coating is: first spin-coat at a low speed of 30 r / s for 20 s, and then accelerate to 750 r / s at an acceleration of 500 r / s and continue to spin-coat for 20 s;

[0071] Step 1.2.5: Place the substrate coated with the liquid film in a blast drying oven, dry and cure it at a temperature of 50 °C for 10 h, and obtain a loose and porous fiber material after the drying and curing is completed;

[0072] Step 1.3: Peel the loose and porous fiber material from the substrate to obtain a fiber structure layer 1.

[0073] Step 2: Prepare a water-sealing layer 2: Based on the prepared high-barrier packaging bag, first add distilled water into the high-barrier packaging bag to discharge the air in the high-barrier packaging bag, and then seal the high-barrier packaging bag to obtain a water-sealing layer 2;

[0074] Among them, the preparation process of the high-barrier packaging bag is as follows:

[0075] Step 2.1: Place polyvinylidene fluoride, nanoclay, and dibutyl phthalate in a forced-air drying oven and dry at 80°C for 6 h to remove moisture and other impurities. Mix the dried polyvinylidene fluoride, nanoclay, and dibutyl phthalate in proportion and stir at a speed of 500 r / min for 30 min. After stirring evenly, a mixed material is obtained. Among them, the nanoclay is 5% of the mass of polyvinylidene fluoride, and the dibutyl phthalate is 10% of the mass of polyvinylidene fluoride.

[0076] Step 2.2: Add the mixed material to a twin-screw extruder for melt blending and extrusion into pellets. Air-cool and pelletize the extruded pellets to obtain modified polyvinylidene fluoride pellets. Among them, the extrusion temperature is 180°C, and the screw speed is 100 r / min.

[0077] Step 2.3: Add the modified polyvinylidene fluoride pellets to the hopper of a blown film machine and blow them into a film to obtain a poly-modified polyvinylidene fluoride film.

[0078] Step 2.4: Cut the modified polyvinylidene fluoride film according to the design requirements to obtain film sheets.

[0079] Step 2.5: Heat-seal the film sheets with a heat-sealing machine to form a high-barrier packaging bag. Among them, the process parameters of heat-sealing are: the heat-sealing temperature is 150°C, the heat-sealing time is 3 s, and the heat-sealing pressure is 0.2 MPa.

[0080] Step 3: Prepare the chlorophyll protective layer 3:

[0081] Step 3.1: Prepare a chlorophyll extraction solution: First, wash the plant leaves with distilled water to remove the dust, impurities, and withered and yellow parts on the surface of the plant leaves. Then, blot the water on the surface of the washed plant leaves with filter paper. After removing the petioles and leaf veins of the plant leaves, cut the plant leaves into leaf pieces of 1 cm 2 in size. Then, mix the leaf pieces and acetone in a volume ratio of 1:10 and place them at room temperature for 24 h to completely dissolve the chlorophyll in the leaf pieces, obtaining a chlorophyll solution. Finally, perform solid-liquid separation on the chlorophyll solution by filtration, and collect the separated supernatant as the chlorophyll extraction solution.

[0082] Step 3.2: Add PVA monomers to distilled water and stir at 80°C until the PVA monomers are completely dissolved to prepare a PVA solution with a mass fraction of 5%, obtaining an aqueous polymer solution.

[0083] Step 3.3: Under stirring conditions, slowly add the chlorophyll extract into the aqueous polymer solution so that the chlorophyll extract is uniformly dispersed in the aqueous polymer solution; continue stirring for 30 min to ensure uniform mixing and form a stable mixture; wherein, the mass ratio between the added chlorophyll extract and the aqueous polymer solution is 1:10.

[0084] Step 3.4: Pour the mixture into a mold, and uniformly coat the mixture on a flat substrate by means of scraping at room temperature to form a uniform thin film; place the substrate coated with the thin film in an oven and dry it at a temperature of 40 °C for 24 h to obtain the chlorophyll protective layer 3.

[0085] Step 4: Prepare the plant leaf-like camouflage material:

[0086] Cut the polyvinyl alcohol waterproof film according to the design requirements to obtain the waterproof layer 4; stack the fiber structure layer 1, the water sealing layer 2, the chlorophyll protective layer 3, and the waterproof layer 4 in sequence from bottom to top to obtain a preform; use polyurethane adhesive to laminate the preform together to obtain the plant leaf-like camouflage material (1), see Figure 2 , the reflectance of the surface of the plant leaf-like camouflage material is 40% - 45%, and it has the "near-infrared plateau" characteristic of green plants in the wavelength range of 780 nm - 1300 nm.

[0087] The above-mentioned plant leaf-like camouflage material (1) includes: a fiber structure layer 1, a water sealing layer 2, a chlorophyll protective layer 3, and a waterproof layer 4 which are arranged in sequence from bottom to top, and adjacent layers are bonded and fixed by polyurethane glue; wherein,

[0088] the fiber structure layer 1 has a loose porous structure and is used to simulate the mesophyll tissue of plant leaves; the water sealing layer 2 is used to provide the water absorption characteristic of plant leaves; the chlorophyll protective layer 3 is used to make the camouflage material have a similar appearance color to plant leaves; the waterproof layer 4 is used to provide waterproof performance.

[0089] Example 2

[0090] Refer to Figure 1 , this example provides a preparation method of a plant leaf-like camouflage material, which specifically includes the following steps:

[0091] Step 1: Prepare the fiber structure layer 1:

[0092] Step 1.1: Clean the surface of the glass sheet, and use the treated glass sheet as a substrate for standby; specifically, place the glass sheet in an anhydrous ethanol solution and perform ultrasonic oscillation treatment for 5 min to remove the contaminants attached to the surface of the glass sheet, take out the glass sheet, wipe it with a lint-free cloth to obtain a glass sheet with a clean surface, and use the glass sheet as a substrate for standby;

[0093] Step 1.2: Prepare a reaction solution by the direct dissolution method, and coat the reaction solution on the surface of the substrate through a high-speed rotary coating process to obtain a loose and porous fiber material; specifically including:

[0094] Step 1.2.1: Add cotton fibers to N,N-dimethylformamide, control the stirring speed at 250 r / min, the temperature at 90 °C, and the stirring time at 4 h until the cotton fibers are dissolved to obtain a uniform fiber solution;

[0095] Step 1.2.2: Add ammonium bicarbonate to the fiber solution, control the stirring speed at 120 r / min, and the stirring time at 0.8 h, and stir evenly to obtain a mixed solution;

[0096] Step 1.2.3: Add glutaraldehyde and hydrochloric acid to the mixed solution, control the reaction temperature at 45 °C, and the cross-linking reaction time at 3.5 h to obtain a reaction solution after cross-linking reaction; wherein, the addition amount of ammonium bicarbonate is 25% of the mass of the cellulose raw material, the addition amount of glutaraldehyde is 7% of the mass of the cotton fibers, and the addition amount of hydrochloric acid is 4% of the mass of the cotton fibers;

[0097] Step 1.2.4: Drop the reaction solution onto the center of the substrate, then fix the substrate on a rotary coater, and form a uniform liquid film on the surface of the substrate through a high-speed rotary coating process; wherein, the process of high-speed rotary coating is: first spin-coat at a low speed of 35 r / s for 18 s, and then accelerate to 800 r / s at an acceleration of 500 r / s and continue to spin-coat for 15 s;

[0098] Step 1.2.5: Place the substrate coated with the liquid film in a forced-air drying oven, dry and cure at a temperature of 60 °C for 9 h, and obtain a loose and porous fiber material after the drying and curing are completed;

[0099] Step 1.3: Peel the loose and porous fiber material from the substrate to obtain fiber structure layer 1.

[0100] Step 2: Prepare the water-sealing layer 2: Based on the prepared high-barrier packaging bag, first add distilled water into the high-barrier packaging bag to discharge the air in the high-barrier packaging bag, and then seal the high-barrier packaging bag to obtain the water-sealing layer 2;

[0101] Among them, the preparation process of the high-barrier packaging bag is as follows:

[0102] Step 2.1: Place polyvinylidene fluoride, nano-clay, and dioctyl phthalate in a blast drying oven and dry at 90°C for 5 h to remove moisture and other impurities. Mix the dried polyvinylidene fluoride, nano-clay, and dioctyl phthalate in proportion and stir at a speed of 500 r / min for 30 min. After stirring evenly, a mixed material is obtained. Among them, the nano-clay is 10% of the mass of polyvinylidene fluoride, and the dioctyl phthalate is 12% of the mass of polyvinylidene fluoride.

[0103] Step 2.2: Add the mixed material into a twin-screw extruder for melt blending and extrusion into pellets. Air-cool and pelletize the extruded pellets to obtain modified polyvinylidene fluoride pellets. Among them, the extrusion temperature is 200°C, and the screw speed is 120 r / min.

[0104] Step 2.3: Add the modified polyvinylidene fluoride pellets into the hopper of a blown film machine and blow them into a film to obtain a poly-modified polyvinylidene fluoride film.

[0105] Step 2.4: Cut the modified polyvinylidene fluoride film according to the design requirements to obtain film sheets.

[0106] Step 2.5: Heat-seal the film sheets with a heat-sealing machine to form a high-barrier packaging bag. Among them, the process parameters of heat-sealing are as follows: the heat-sealing temperature is 170°C, the heat-sealing time is 3 s, and the heat-sealing pressure is 0.2 MPa.

[0107] Step 3: Prepare the chlorophyll protective layer 3:

[0108] Step 3.1: Prepare a chlorophyll extract: First, wash the plant leaves with distilled water to remove the dust, impurities, and withered and yellow parts on the surface of the plant leaves. Then, blot the water on the surface of the washed plant leaves with filter paper. After removing the petioles and leaf veins of the plant leaves, cut the plant leaves into leaf pieces of 1 cm 2 in size. Then, mix the leaf pieces and acetone in a volume ratio of 1:15 and place them at room temperature for 20 h to completely dissolve the chlorophyll in the leaf pieces, obtaining a chlorophyll solution. Finally, perform solid-liquid separation on the chlorophyll solution by filtration, and collect the separated supernatant as the chlorophyll extract.

[0109] Step 3.2: Add PVA monomers to distilled water and stir at 80°C until the PVA monomers are completely dissolved to prepare a PVA solution with a mass fraction of 5%, obtaining an aqueous polymer solution.

[0110] Step 3.3: Under stirring conditions, slowly add the chlorophyll extract into the aqueous polymer solution so that the chlorophyll extract is uniformly dispersed in the aqueous polymer solution; continue stirring for 25 min to ensure uniform mixing and form a stable mixture; wherein, the mass ratio between the added chlorophyll extract and the aqueous polymer solution is 1:15;

[0111] Step 3.4: Pour the mixture into a mold and evenly coat the mixture on a flat substrate by means of doctor blading at room temperature to form a uniform thin film; place the substrate coated with the thin film in an oven and dry it at a temperature of 45°C for 20 h to obtain the chlorophyll protection layer 3.

[0112] Step 4: Prepare the plant leaf-like camouflage material:

[0113] Cut the polyvinyl alcohol waterproof film according to the design requirements to obtain the waterproof layer 4; stack the fiber structure layer 1, the water sealing layer 2, the chlorophyll protection layer 3 and the waterproof layer 4 in order from bottom to top to obtain a preform; use a polyurethane adhesive to composite the preform together to obtain the plant leaf-like camouflage material (II), the reflectance of the surface of the plant leaf-like camouflage material (II) is 45% - 50%, and it has the "near-infrared plateau" characteristic of green plants between the wavelength range of 780 nm - 1300 nm.

[0114] It should be supplementary explained that the structure of the plant leaf-like camouflage material (II) prepared in this embodiment is the same as that of the plant leaf-like camouflage material (I) prepared in Embodiment 1, and will not be elaborated here.

[0115] Embodiment 3

[0116] This embodiment provides a preparation method of a plant leaf-like camouflage material, which specifically includes the following steps:

[0117] Step 1: Prepare the fiber structure layer 1:

[0118] Step 1.1: Clean the surface of the glass sheet and use the treated glass sheet as a substrate for standby; specifically, place the glass sheet in an anhydrous ethanol solution and perform ultrasonic oscillation treatment for 10 min to remove the contaminants attached to the surface of the glass sheet, take out the glass sheet and wipe it with a lint-free cloth to obtain a glass sheet with a clean surface, and use this glass sheet as a substrate for standby;

[0119] Step 1.2: Prepare a reaction solution by the direct dissolution method and coat the reaction solution on the surface of the substrate through a high-speed rotary coating process to obtain a porous fiber material; specifically include:

[0120] Step 1.2.1: Add cotton fibers into N-methylmorpholine-N-oxide, control the stirring speed at 300 r / min, the temperature at 110 °C, and the stirring time for 3 h until the cotton fibers are dissolved to obtain a uniform fiber solution;

[0121] Step 1.2.2: Add sucrose into the fiber solution, control the stirring speed at 180 r / min and the stirring time for 0.6 h, and obtain a mixed solution after stirring evenly;

[0122] Step 1.2.3: Add glutaraldehyde and hydrochloric acid into the mixed solution, control the reaction temperature at 50 °C and the cross-linking reaction time for 3 h, and obtain a reaction solution after cross-linking reaction; wherein, the addition amount of sucrose is 30% of the mass of the cotton fibers, the addition amount of glutaraldehyde is 10% of the mass of the cotton fibers, and the addition amount of sulfuric acid is 5% of the mass of the cotton fibers;

[0123] Step 1.2.4: Drop the reaction solution onto the center of the substrate, then fix the substrate on a spin coater, and form a uniform liquid film on the surface of the substrate through a high-speed spin coating process; wherein, the high-speed spin coating process is: first spin coat at a low speed of 40 r / s for 15 s, and then accelerate to 850 r / s at an acceleration of 500 r / s and continue to spin coat for 13 s;

[0124] Step 1.2.5: Place the substrate coated with the liquid film in a blast drying oven, dry and cure at a temperature of 75 °C for 7 h, and obtain a porous fibrous material after drying and curing;

[0125] Step 1.3: Peel the porous fibrous material from the substrate to obtain the fiber structure layer 1.

[0126] Step 2: Prepare the water-blocking layer 2: Based on the prepared high-barrier packaging bag, first add distilled water into the high-barrier packaging bag to discharge the air in the high-barrier packaging bag, and then seal the high-barrier packaging bag to obtain the water-blocking layer 2;

[0127] Among them, the preparation process of the high-barrier packaging bag is as follows:

[0128] Step 2.1: Place polyvinylidene fluoride, graphene, and dibutyl sebacate in a blast drying oven and dry at a temperature of 100 °C for 4 h to remove moisture and other impurities; mix the dried polyvinylidene fluoride, nanoclay, and dioctyl phthalate in proportion and stir at a speed of 500 r / min for 30 min. After stirring evenly, obtain a mixed material; wherein, graphene is 15% of the mass of polyvinylidene fluoride, and dibutyl sebacate is 20% of the mass of polyvinylidene fluoride;

[0129] Step 2.2: Add the mixed material into a twin-screw extruder for melt blending and extrusion into pellets. Air-cool the extruded pellets and cut them into particles to obtain modified polyvinylidene fluoride particles. Among them, the extrusion temperature is 220 °C and the screw speed is 180 r / min.

[0130] Step 2.3: Add the modified polyvinylidene fluoride particles into the hopper of a blown film machine to blow them into a film to obtain a poly-modified polyvinylidene fluoride film.

[0131] Step 2.4: Cut the modified polyvinylidene fluoride film according to the design requirements to obtain film sheets.

[0132] Step 2.5: Heat-seal the film sheets with a heat-sealing machine to form a high-barrier packaging bag. Among them, the process parameters of heat-sealing are as follows: the heat-sealing temperature is 165 °C, the heat-sealing time is 3 s, and the heat-sealing pressure is 0.25 MPa.

[0133] Step 3: Prepare the chlorophyll protective layer 3:

[0134] Step 3.1: Prepare a chlorophyll extract: First, wash the plant leaves with distilled water to remove the dust, impurities, and withered and yellow parts on the surface of the plant leaves. Then, blot the water on the surface of the washed plant leaves with filter paper, remove the petioles and leaf veins of the plant leaves, and cut the plant leaves into leaf pieces of 1.5 cm 2 in size. Then, mix the leaf pieces and acetone in a volume ratio of 1:17 and place them at room temperature for 18 h to completely dissolve the chlorophyll in the leaf pieces to obtain a chlorophyll solution. Finally, perform solid-liquid separation on the chlorophyll solution by filtration, and collect the separated supernatant as the chlorophyll extract.

[0135] Step 3.2: Add PVA monomers into distilled water and stir at a temperature of 88 °C until the PVA monomers are completely dissolved to prepare a PVA solution with a mass fraction of 8% to obtain an aqueous polymer solution.

[0136] Step 3.3: Under stirring conditions, slowly add the chlorophyll extract into the aqueous polymer solution to uniformly disperse the chlorophyll extract in the aqueous polymer solution. Continue stirring for 20 min to ensure uniform mixing and form a stable mixture. Among them, the mass ratio between the added chlorophyll extract and the aqueous polymer solution is 1:18.

[0137] Step 3.4: Pour the mixture into a mold, and evenly coat the mixture on a flat substrate by means of scraping at room temperature to form a uniform film. Place the substrate coated with the film in an oven and dry it at a temperature of 50 °C for 17 h to obtain the chlorophyll protective layer 3.

[0138] Step 4: Prepare the plant leaf-mimicking camouflage material:

[0139] Cut the polyvinyl alcohol waterproof film according to the design requirements to obtain the waterproof layer 4; stack the fiber structure layer 1, the water sealing layer 2, the chlorophyll protection layer 3, and the waterproof layer 4 in order from bottom to top to obtain a preform; use polyurethane adhesive to composite the preform together to obtain the plant leaf-mimicking camouflage material (III). The reflectivity of the surface of the plant leaf-mimicking camouflage material (III) is 45% - 50%, and it has the "near-infrared plateau" characteristics of green plants in the wavelength range of 780nm - 1300nm.

[0140] It should be noted that the structure of the plant leaf-mimicking camouflage material (III) prepared in this example is the same as that of the plant leaf-mimicking camouflage material (I) prepared in Example 1, and will not be elaborated here.

[0141] Example 4

[0142] This example provides a preparation method of a plant leaf-mimicking camouflage material, which specifically includes the following steps:

[0143] Step 1: Prepare the fiber structure layer 1:

[0144] Clean the surface of the glass sheet, and use the treated glass sheet as a substrate for later use; specifically, the surface of the glass sheet can be wiped with anhydrous ethanol 10 times to remove the pollutants attached to the surface of the glass sheet, and a glass sheet with a clean surface is obtained and used as a substrate for later use;

[0145] Prepare a reaction solution by the direct dissolution method, and coat the reaction solution on the surface of the substrate through a high-speed rotary coating process to obtain a porous fiber material; specifically including:

[0146] Add wood pulp fibers into 1-butyl-3-methylimidazolium chloride, control the stirring speed at 350r / min, the temperature at 100°C, and the stirring time at 4h until the wood pulp fibers are dissolved to obtain a uniform fiber solution;

[0147] Add glucose into the fiber solution, control the stirring speed at 200r / min, and the stirring time at 0.6h, and obtain a mixed solution after stirring evenly;

[0148] Add formaldehyde and sulfuric acid into the mixed solution, control the reaction temperature at 55°C, and the cross-linking reaction time at 3h. After the cross-linking reaction, a reaction solution is obtained; among them, the addition amount of glucose is 40% of the mass of the wood pulp fibers, the addition amount of formaldehyde is 12% of the mass of the wood pulp fibers, and the addition amount of sulfuric acid is 6% of the mass of the cotton fibers;

[0149] Step 1.2.4: Drop the reaction solution onto the center of the substrate, then fix the substrate on a spin coater. Through the high-speed spin coating process, a uniform liquid film is formed on the surface of the substrate. Among them, the high-speed spin coating process is as follows: First, spin coat at a low speed of 45 r / s for 12 s, and then accelerate to 900 r / s at an acceleration of 500 r / s and continue to spin coat for 12 s;

[0150] Step 1.2.5: Place the substrate coated with the liquid film in a forced air drying oven and dry and cure it at a temperature of 85 °C for 5 h. After the drying and curing are completed, a loose and porous fiber material is obtained;

[0151] Step 1.3: Peel the loose and porous fiber material from the substrate to obtain the fiber structure layer 1.

[0152] Step 2: Prepare the water sealing layer 2: Based on the prepared high-barrier packaging bag, first add distilled water into the high-barrier packaging bag to discharge the air in the high-barrier packaging bag, and then seal the high-barrier packaging bag to obtain the water sealing layer 2;

[0153] Among them, the preparation process of the high-barrier packaging bag is as follows:

[0154] Step 2.1: Place polyvinylidene fluoride, carbon nanotubes, and dioctyl adipate in a forced air drying oven and dry them at a temperature of 120 °C for 2 h to remove moisture and other impurities; Mix the dried polyvinylidene fluoride, carbon nanotubes, and dioctyl adipate in proportion and stir at a speed of 500 r / min for 30 min. After stirring evenly, a mixed material is obtained. Among them, the carbon nanotubes are 17% of the mass of polyvinylidene fluoride, and dioctyl adipate is 25% of the mass of polyvinylidene fluoride;

[0155] Step 2.2: Add the mixed material into a twin-screw extruder for melt blending and extrusion into pellets, and air-cool and pelletize the extruded pellets to obtain modified polyvinylidene fluoride pellets. Among them, the extrusion temperature is 250 °C, and the screw speed is 200 r / min;

[0156] Step 2.3: Add the modified polyvinylidene fluoride pellets into the hopper of a blown film machine and blow them into a film to obtain a poly-modified polyvinylidene fluoride film;

[0157] Step 2.4: Cut the modified polyvinylidene fluoride film according to the design requirements to obtain film sheets;

[0158] Step 2.5: Heat-seal the film sheets through a heat-sealing machine to form a high-barrier packaging bag. Among them, the process parameters of the heat-sealing are as follows: the heat-sealing temperature is 170 °C, the heat-sealing time is 1.2 s, and the heat-sealing pressure is 0.3 MPa.

[0159] Step 3: Prepare the chlorophyll protection layer 3:

[0160] Step 3.1: Prepare the chlorophyll extraction solution. First, wash the plant leaves with distilled water to remove the dust, impurities, and withered parts on the surface of the plant leaves. Then, blot the water on the surface of the washed plant leaves with filter paper. After removing the petioles and leaf veins of the plant leaves, cut the plant leaves into leaf pieces of 1.5 cm 2 in size. Then, mix the leaf pieces with acetone-ether in a volume ratio of 1:20 and place them at room temperature for 15 h to completely dissolve the chlorophyll in the leaf pieces, obtaining a chlorophyll solution. Finally, perform solid-liquid separation on the chlorophyll solution by filtration, and collect the separated supernatant as the chlorophyll extraction solution. Among them, in the acetone-ether system, the volume ratio between acetone and ether is 3:1;

[0161] Step 3.2: Add the PVA monomer to distilled water and stir at a temperature of 90 °C until the PVA monomer is completely dissolved to prepare a PVA solution with a mass fraction of 10%, obtaining an aqueous polymer solution;

[0162] Step 3.3: Under stirring conditions, slowly add the chlorophyll extraction solution to the aqueous polymer solution to uniformly disperse the chlorophyll extraction solution in the aqueous polymer solution. Continue stirring for 25 min to ensure uniform mixing and form a stable mixed solution. Among them, the mass ratio between the added chlorophyll extraction solution and the aqueous polymer solution is 1:20;

[0163] Step 3.4: Pour the mixed solution into a mold and uniformly coat the mixed solution on a flat substrate by scraping at room temperature to form a uniform thin film. Place the substrate coated with the thin film in an oven and dry it at a temperature of 55 °C for 15 h to obtain the chlorophyll protection layer 3.

[0164] Step 4: Prepare the plant leaf-like camouflage material:

[0165] Cut the polyvinyl alcohol waterproof film according to the design requirements to obtain the waterproof layer 4. Stack the fiber structure layer 1, the water sealing layer 2, the chlorophyll protection layer 3, and the waterproof layer 4 in order from bottom to top to obtain a preform. Use polyurethane adhesive to composite the preform together to obtain the plant leaf-like camouflage material (IV). The reflectance on the surface of the plant leaf-like camouflage material (IV) is 48% - 52%, and it has the "near-infrared plateau" characteristic of green plants in the wavelength range of 780 nm - 1300 nm.

[0166] It should be added that the structure of the plant leaf-like camouflage material (IV) prepared in this example is the same as that of the plant leaf-like camouflage material (I) prepared in Example 1, and will not be elaborated here.

[0167] Example 5

[0168] This embodiment provides a method for preparing a plant leaf - like camouflage material, which specifically includes the following steps:

[0169] Step 1: Prepare the fiber structure layer 1:

[0170] Step 1.1: Clean the surface of the glass slide, and use the treated glass slide as a substrate for standby; specifically, the surface of the glass slide can be wiped with anhydrous ethanol 8 times to remove the pollutants attached to the surface of the glass slide, and a glass slide with a clean surface is obtained and used as a substrate for standby;

[0171] Step 1.2: Prepare a reaction solution by the direct dissolution method, and coat the reaction solution on the surface of the substrate through a high - speed rotary coating process to obtain a porous fiber material; specifically, it includes:

[0172] Step 1.2.1: Add wood pulp fibers into N - methylpyrrolidone, control the stirring speed at 350 r / min, the temperature at 120 °C, and the stirring time at 2 h until the wood pulp fibers are dissolved to obtain a uniform fiber solution;

[0173] Step 1.2.2: Add sodium chloride into the fiber solution, control the stirring speed at 250 r / min, and the stirring time at 0.5 h, and obtain a mixed solution after stirring evenly;

[0174] Step 1.2.3: Add glutaraldehyde and hydrochloric acid into the mixed solution, control the reaction temperature at 55 °C, and the cross - linking reaction time at 4 h, and obtain a reaction solution after cross - linking reaction; among them, the addition amount of sodium chloride is 45% of the mass of the wood pulp fibers, the addition amount of glutaraldehyde is 13% of the mass of the wood pulp fibers, and the addition amount of hydrochloric acid is 7% of the mass of the wood pulp fibers;

[0175] Step 1.2.4: Drop the reaction solution onto the center of the substrate, then fix the substrate on a rotary coater, and form a uniform liquid film on the surface of the substrate through a high - speed rotary coating process; among them, the process of high - speed rotary coating is: first spin - coat at a low speed of 45 r / s for 12 s, and then accelerate to 1000 r / s at an acceleration of 500 r / s and continue to spin - coat for 10 s;

[0176] Step 1.2.5: Place the substrate coated with the liquid film in a blast drying oven, dry and cure at a temperature of 85 °C for 6 h, and obtain a porous fiber material after the drying and curing is completed;

[0177] Step 1.3: Peel the porous fiber material from the substrate to obtain the fiber structure layer 1.

[0178] Step 2. Prepare the water-sealing layer 2: Based on the prepared high-barrier packaging bag, first add distilled water into the high-barrier packaging bag to expel the air inside the high-barrier packaging bag, and then seal the high-barrier packaging bag to obtain the water-sealing layer 2;

[0179] Among them, the preparation process of the high-barrier packaging bag is as follows:

[0180] Step 2.1. Place polyvinylidene fluoride, graphene, and triphenyl phosphate in a blast drying oven and dry at a temperature of 100 °C for 4 h to remove moisture and other impurities; mix the dried polyvinylidene fluoride, graphene, and triphenyl phosphate in proportion and stir at a speed of 500 r / min for 30 min. After stirring evenly, obtain a mixed material; among them, graphene is 20% of the mass of polyvinylidene fluoride, and triphenyl phosphate is 25% of the mass of polyvinylidene fluoride;

[0181] Step 2.2. Add the mixed material into a twin-screw extruder for melt blending and extrusion into pellets, and air-cool and pelletize the extruded pellets to obtain modified polyvinylidene fluoride pellets; among them, the extrusion temperature is 250 °C and the screw speed is 200 r / min;

[0182] Step 2.3. Add the modified polyvinylidene fluoride pellets into the hopper of a blown film machine and blow them into a film to obtain a poly-modified polyvinylidene fluoride film;

[0183] Step 2.4. Cut the modified polyvinylidene fluoride film according to the design requirements to obtain film sheets;

[0184] Step 2.5. Heat-seal the film sheets through a heat-sealing machine to form a high-barrier packaging bag; among them, the process parameters of heat-sealing are as follows: the heat-sealing temperature is 180 °C, the heat-sealing time is 1.2 s, and the heat-sealing pressure is 0.4 MPa.

[0185] Step 3. Prepare the chlorophyll protection layer 3:

[0186] Step 3.1. Prepare the chlorophyll extract: First, wash the plant leaves with distilled water to remove the dust, impurities, and withered and yellow parts on the surface of the plant leaves; then blot the water on the surface of the washed plant leaves with filter paper, remove the petioles and leaf veins of the plant leaves, and cut the plant leaves into leaf pieces of 2 cm 2 in size; then mix the leaf pieces and methanol-petroleum ether in a volume ratio of 1:20 and place them at room temperature for 15 h to completely dissolve the chlorophyll in the leaf pieces to obtain a chlorophyll solution; finally, perform solid-liquid separation on the chlorophyll solution by filtration method, and collect the separated supernatant as the chlorophyll extract; among them, in the methanol-petroleum ether system, the volume ratio between methanol and petroleum ether is 1.5:1;

[0187] Step 3.2: Add PVA monomers into distilled water, stir at 90 °C until the PVA monomers are completely dissolved, and prepare a PVA solution with a mass fraction of 10% to obtain an aqueous polymer solution;

[0188] Step 3.3: Under stirring conditions, slowly add the chlorophyll extract into the aqueous polymer solution to uniformly disperse the chlorophyll extract in the aqueous polymer solution; continue stirring for 25 min to ensure uniform mixing and form a stable mixture; wherein, the mass ratio between the added chlorophyll extract and the aqueous polymer solution is 1:20;

[0189] Step 3.4: Pour the mixture into a mold, and uniformly coat the mixture on a flat substrate by means of scraping at room temperature to form a uniform thin film; place the substrate coated with the thin film in an oven and dry it at 60 °C for 12 h to obtain the chlorophyll protection layer 3.

[0190] Step 4: Prepare the plant leaf-like camouflage material:

[0191] Cut the polyvinyl alcohol waterproof film according to the design requirements to obtain the waterproof layer 4; stack the fiber structure layer 1, the water sealing layer 2, the chlorophyll protection layer 3 and the waterproof layer 4 in the order from bottom to top to obtain a preform; use polyurethane adhesive to composite the preform together to obtain the plant leaf-like camouflage material (five), and the reflectance of the surface of the plant leaf-like camouflage material (five) is 50% - 55%, and it has the "near-infrared plateau" characteristic of green plants in the wavelength range of 780 nm - 1300 nm.

[0192] It should be supplementary explained that the structure of the plant leaf-like camouflage material (five) prepared in this embodiment is the same as that of the plant leaf-like camouflage material (one) prepared in Embodiment 1, and will not be elaborated here.

[0193] Embodiment 6

[0194] This embodiment provides a preparation method of a plant leaf-like camouflage material, which specifically includes the following steps:

[0195] Step 1: Prepare the fiber structure layer 1:

[0196] Step 1.1: Clean the surface of the glass slide, and use the treated glass slide as a substrate for standby; specifically, place the glass slide in an anhydrous ethanol solution and perform ultrasonic oscillation treatment for 5 min to remove the pollutants attached to the surface of the glass slide, take out the glass slide, wipe it with a lint-free cloth to obtain a glass slide with a clean surface, and use the glass slide as a substrate for standby;

[0197] Step 1.2: Prepare a reaction solution by the direct dissolution method and coat the reaction solution on the surface of the substrate through a high-speed rotary coating process to obtain a loose and porous fiber material; specifically including:

[0198] Step 1.2.1: Add wood pulp fibers into N-methyl morpholine-N-oxide, control the stirring speed at 500 r / min, the temperature at 120 °C, and the stirring time for 2 h until the wood pulp fibers are dissolved to obtain a uniform fiber solution;

[0199] Step 1.2.2: Add ammonium bicarbonate into the fiber solution, control the stirring speed at 300 r / min, and the stirring time for 0.5 h, and obtain a mixed solution after stirring evenly;

[0200] Step 1.2.3: Add formaldehyde and sulfuric acid into the mixed solution, control the reaction temperature at 60 °C, and the cross-linking reaction time for 2 h, and obtain a reaction solution after cross-linking reaction; wherein, the addition amount of ammonium bicarbonate is 50% of the mass of the cotton fiber, the addition amount of formaldehyde is 15% of the mass of the wood pulp fiber, and the addition amount of sulfuric acid is 7% of the mass of the wood pulp fiber;

[0201] Step 1.2.4: Drop the reaction solution onto the center of the substrate, then fix the substrate on a rotary coater, and form a uniform liquid film on the surface of the substrate through a high-speed rotary coating process; wherein, the process of high-speed rotary coating is: first spin-coat at a low speed of 50 r / s for 10 s, and then accelerate to 1000 r / s at an acceleration of 500 r / s and continue to spin-coat for 10 s;

[0202] Step 1.2.5: Place the substrate coated with the liquid film in a forced-air drying oven, dry and cure at a temperature of 90 °C for 5 h, and obtain a loose and porous fiber material after the drying and curing is completed;

[0203] Step 1.3: Peel the loose and porous fiber material from the substrate to obtain fiber structure layer 1.

[0204] Step 2: Prepare a water-sealing layer 2: Based on the prepared high-barrier packaging bag, first add distilled water into the high-barrier packaging bag to discharge the air in the high-barrier packaging bag, and then seal the high-barrier packaging bag to obtain a water-sealing layer 2;

[0205] Among them, the preparation process of the high-barrier packaging bag is as follows:

[0206] Step 2.1: Place polyvinylidene fluoride, nano-clay, and dibutyl phthalate in a forced-air drying oven and dry at 120 °C for 2 h to remove moisture and other impurities. Mix the dried polyvinylidene fluoride, nano-clay, and dibutyl phthalate in proportion and stir at a speed of 500 r / min for 30 min. After stirring evenly, a mixed material is obtained. Among them, the nano-clay is 20% of the mass of polyvinylidene fluoride, and the dibutyl phthalate is 30% of the mass of polyvinylidene fluoride.

[0207] Step 2.2: Add the mixed material into a twin-screw extruder for melt blending and extrusion into pellets. Air-cool and pelletize the extruded pellets to obtain modified polyvinylidene fluoride pellets. Among them, the extrusion temperature is 250 °C, and the screw speed is 300 r / min.

[0208] Step 2.3: Add the modified polyvinylidene fluoride pellets into the hopper of a blown film machine and blow them into a film to obtain a poly-modified polyvinylidene fluoride film.

[0209] Step 2.4: Cut the modified polyvinylidene fluoride film according to the design requirements to obtain film sheets.

[0210] Step 2.5: Heat-seal the film sheets with a heat-sealing machine to form a high-barrier packaging bag. Among them, the process parameters of heat-sealing are as follows: the heat-sealing temperature is 180 °C, the heat-sealing time is 1 s, and the heat-sealing pressure is 0.5 MPa.

[0211] Step 3: Prepare the chlorophyll protective layer 3:

[0212] Step 3.1: Prepare a chlorophyll extract: First, wash the plant leaves with distilled water to remove the dust, impurities, and withered and yellow parts on the surface of the plant leaves. Then, blot the water on the surface of the washed plant leaves with filter paper. After removing the petioles and leaf veins of the plant leaves, cut the plant leaves into leaf pieces of 2 cm 2 in size. Then, mix the leaf pieces and acetone in a volume ratio of 1:20 and place them at room temperature for 12 h to completely dissolve the chlorophyll in the leaf pieces to obtain a chlorophyll solution. Finally, perform solid-liquid separation on the chlorophyll solution by filtration, and collect the separated supernatant as the chlorophyll extract.

[0213] Step 3.2: Add PVA monomers into distilled water and stir at 90 °C until the PVA monomers are completely dissolved to prepare a PVA solution with a mass fraction of 10% to obtain an aqueous polymer solution.

[0214] Step 3.3: Under stirring conditions, slowly add the chlorophyll extract into the aqueous polymer solution so that the chlorophyll extract is uniformly dispersed in the aqueous polymer solution; continue stirring for 30 min to ensure uniform mixing and form a stable mixture; wherein, the mass ratio between the added chlorophyll extract and the aqueous polymer solution is 1:20;

[0215] Step 3.4: Pour the mixture into a mold, and evenly coat the mixture on a flat substrate by means of scraping at room temperature to form a uniform thin film; place the substrate coated with the thin film in an oven and dry it at a temperature of 60 °C for 12 h to obtain the chlorophyll protection layer 3.

[0216] Step 4: Prepare the plant leaf-like camouflage material:

[0217] Cut the polyvinyl alcohol waterproof film according to the design requirements to obtain the waterproof layer 4; stack the fiber structure layer 1, the water sealing layer 2, the chlorophyll protection layer 3 and the waterproof layer 4 in the order from bottom to top to obtain a preform; use polyurethane adhesive to composite the preform together to obtain the plant leaf-like camouflage material (VI), and the reflectance of the surface of the plant leaf-like camouflage material (VI) is 55% - 60%, and it has the "near-infrared plateau" characteristic of green plants in the wavelength range of 780 nm - 1300 nm.

[0218] It should be supplementary explained that the structure of the plant leaf-like camouflage material (VI) prepared in this embodiment is the same as that of the plant leaf-like camouflage material (I) prepared in Embodiment 1, and will not be elaborated here.

[0219] In summary, the preparation method provided by the present invention can prepare a plant leaf-like camouflage material, the surface reflectance of which is as high as 40% - 60%, and it has the "near-infrared plateau" characteristic of green plants in the wavelength range of 780 - 1300 nm. Refer to Figure 3 。

[0220] The above are only specific embodiments of the present invention, which enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0221] It should be understood that the present invention is not limited to the above-described content and can be modified and changed without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A preparation method of a plant leaf-mimicking camouflage material, characterized in that, First, prepare the fiber structure layer (1), the water-blocking layer (2), and the chlorophyll protection layer (3) separately. Then, stack the fiber structure layer (1), the water-blocking layer (2), the chlorophyll protection layer (3), and the waterproof layer (4) in order from bottom to top to obtain a preform. Finally, adhesively bond the preform to obtain the plant leaf-like camouflage material.

2. The preparation method of the plant leaf-like camouflage material according to claim 1, characterized in that, Specifically, it includes the following steps: Step 1. Prepare the fiber structure layer (1): Use a specific process to construct a loose and porous fiber material into the fiber structure layer (1); Step 2. Prepare the water-blocking layer (2): Based on the prepared high-barrier packaging bag, first add distilled water into the high-barrier packaging bag to expel the air in the high-barrier packaging bag, and then seal the high-barrier packaging bag to obtain the water-blocking layer (2); Step 3. Prepare the chlorophyll protection layer (3): Prepare the chlorophyll extract and the polymer aqueous solution respectively. Mix the chlorophyll extract and the polymer aqueous solution evenly according to the mass ratio of 1: (10 - 20), and then pour the mixture into a mold. After coating and drying, obtain the chlorophyll protection layer (3); Step 4. Prepare the plant leaf-like camouflage material: Stack the fiber structure layer (1), the water-blocking layer (2), the chlorophyll protection layer (3), and the waterproof layer (4) in order from bottom to top to obtain a preform. After adhesively bonding the preform, obtain the plant leaf-like camouflage material.

3. The preparation method of the plant leaf-like camouflage material according to claim 2, wherein Step 1 specifically includes: Step 1.

1. Clean the surface of the glass slide, and use the treated glass slide as the substrate for standby; Step 1.

2. Prepare the reaction solution by the direct dissolution method, and coat the reaction solution on the surface of the substrate through the high-speed rotary coating process to obtain a loose and porous fiber material; Step 1.

3. Peel the loose and porous fiber material from the substrate to obtain the fiber structure layer (1).

4. The preparation method of the plant leaf-like camouflage material according to claim 3, characterized in that, Step 1.2 specifically includes: Step 1.2.

1. Add the cellulose raw material into the first solvent, control the stirring speed at 200 - 500 r / min, the temperature at 80 - 120 °C, and the stirring time at 2 - 5 h until the cellulose raw material is completely dissolved to obtain a uniform fiber solution; Step 1.2.

2. Add the pore-forming agent into the fiber solution, control the stirring speed at 100 - 300 r / min, and the stirring time at 0.5 - 1 h. After stirring evenly, obtain a mixed solution; Step 1.2.

3. Add the cross-linking agent and the catalyst into the mixed solution, control the reaction temperature at 40 - 60 °C, and the cross-linking reaction time at 2 - 4 h. After the cross-linking reaction, obtain the reaction solution; Step 1.2.

4. After dropping the reaction solution onto the center of the substrate, fix the substrate on the rotary coater, and form a uniform liquid film on the surface of the substrate through the high-speed rotary coating process; Step 1.2.

5. Place the substrate coated with the liquid film in a drying device, control the drying temperature at 50 - 90 °C, and the curing time at 5 - 10 h. After the drying and curing are completed, obtain a loose and porous fiber material.

5. The preparation method of the plant leaf-mimicking camouflage material according to claim 4, wherein In Step 1.2.2, the added mass of the pore-forming agent is 20% - 50% of the cellulose raw material.

6. The preparation method of the plant leaf-mimicking camouflage material according to claim 4, characterized in that, In step 1.2.3, the added mass of the cross-linking agent is 5% to 15% of the mass of the cellulose raw material, and the added mass of the catalyst is 3% to 7% of the mass of the cellulose raw material.

7. The preparation method of the plant leaf-mimicking camouflage material according to claim 2, wherein In step 2, the preparation process of the high barrier packaging bag is as follows: Step 2.1, mixing the dried polyvinylidene fluoride, the modifier, and the plasticizer in a preset mass ratio, stirring evenly, to obtain a mixed material; wherein the mass ratio of the polyvinylidene fluoride, the modifier, and the plasticizer is 100: (5-20): (10-30); Step 2.2, adding the mixed material into a twin-screw extruder for melt blending and extruding particles, air-cooling the extruded particles, and pelletizing to obtain modified polyvinylidene fluoride particles; Step 2.3, adding the modified polyvinylidene fluoride particles into the hopper of a film blowing machine and blowing them into a film to obtain a modified polyvinylidene fluoride film; Step 2.4, cutting the modified polyvinylidene fluoride film to obtain a film sheet; Step 2.5: heat-seal the film sheet with a heat sealer to obtain a high-barrier packaging bag.

8. The preparation method of the plant leaf-like camouflage material according to claim 2, wherein The preparation process of the chlorophyll extract in step 3 is as follows: Wash the plant leaves with distilled water, use filter paper to absorb the water on the surface of the washed plant leaves, and then cut the dried plant leaves into small pieces of 1 to 2 cm2; The leaf pieces and the organic solvent are mixed in a volume ratio of 1:(10-20), and then placed at room temperature for 12-24 hours to ensure the dissolution of chlorophyll in the leaf pieces, thereby obtaining a chlorophyll solution; The chlorophyll solution is subjected to solid-liquid separation by filtration, and the separated supernatant is collected as the chlorophyll extract.

9. The preparation method of the plant leaf-mimicking camouflage material according to claim 2, wherein, The preparation process of the polymer aqueous solution in step 3 is as follows: PVA monomer is added into distilled water, and stirred at a temperature of 80-90° C. until the PVA monomer is completely dissolved, to prepare a PVA solution with a mass fraction of 5%-10%.

10. A plant leaf-mimicking camouflage material prepared by the preparation method according to any one of claims 1 to 9, characterized in that, The reflectivity of the surface of the plant leaf imitation camouflage material is 40% to 60%, and it has the "near-infrared plateau" characteristics of green plants between the 780-1300nm band.

Images