Preparation method of bionic camouflage film with visible light-near infrared reflection spectrum characteristics of plant leaves
By combining polyvinyl alcohol matrix with specific pigments, a biomimetic camouflage film was prepared that has a reflectivity highly similar to that of osmanthus leaves in the visible to near-infrared band. This solves the problems of low spectral matching and insufficient photostability in existing technologies, and achieves a full-band spectral camouflage effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-18
- Publication Date
- 2026-03-10
AI Technical Summary
Existing biomimetic camouflage materials have low spectral matching in the visible-near-infrared band, making it difficult to simultaneously reproduce typical spectral features such as green reflection peaks, red absorption valleys and red edges, high reflectance plateaus and water absorption valleys. Furthermore, their photostability is insufficient and their manufacturing process is complex, making it difficult to achieve full-band spectral camouflage against a vegetation background.
Using polyvinyl alcohol as the film-forming matrix, and combining it with pigments such as iron yellow, ultramarine, alizarin green and copper chromate black, a biomimetic camouflage film was prepared by dissolving, ultrasonically dispersing and mixing. The reflectance curve of the film in the 300~2500nm band is highly similar to that of osmanthus leaves, thus achieving full-band spectral camouflage.
The prepared biomimetic camouflage film has a correlation coefficient of no less than 0.96 with the reflectance curve of osmanthus leaves in the 300~2500nm band, exhibiting good spectral camouflage performance and visual camouflage effect. The process is simple and the raw materials are readily available, making it suitable for outdoor applications.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of plant leaf optical camouflage materials, in particular to a preparation method of a bionic camouflage film with plant leaf visible light-near infrared reflection spectrum characteristics, and belongs to the field of military camouflage materials and environmental spectrum bionic materials. BACKGROUND
[0002] The green plant background is a typical natural environment where various camouflage targets are located, and the spectral detection technology has high sensitivity in target identification under the vegetation background. The leaves of evergreen plants such as osmanthus represent the typical characteristics of the reflection spectrum under sunlight in the visible light-near infrared band: in the visible light range, the reflectivity is low in the blue and red light regions, there is an obvious reflection peak in the green light region, and the reflectivity rapidly increases near the red edge; in the near infrared region, the reflectivity is generally high and forms a near infrared high reflection platform; thereafter, a water absorption valley is formed due to the presence of water in the leaves. The above continuous spectral morphology not only determines the visual color of osmanthus leaves, but also constitutes the overall spectral characteristics of the osmanthus leaves from visible light to near infrared, which provides a key reference for spectral bionic camouflage.
[0003] Most of the existing camouflage materials adjust the visual color of the coating by selecting single or a small number of green pigments, so that the target is close to the vegetation background under naked eye observation, but they often only focus on the reflectivity of certain wave bands, and it is difficult to reproduce the green peak, red light absorption valley and red edge, high reflection platform and water absorption valley and other detailed characteristics in the whole wave band of 300-2500 nm. Under the condition of spectral detection, even if the target and the background are similar in color under naked eye observation, the systematic deviation of the reflectivity curve in multiple wave bands may still be amplified by the identification algorithm, thereby reducing the camouflage effect.
[0004] On the other hand, some studies attempt to directly use natural chlorophyll or its derivatives to improve spectral matching, but such pigments have problems such as poor light stability, easy aging, complex formula, limited source, etc., which are not conducive to long-term field application. Therefore, a bionic camouflage film preparation method is needed, which has easily available raw materials, simple process, good spectral adjustability and high correlation with the reflection spectrum of osmanthus leaves in the wave band of 300-2500 nm, so as to improve the full wave band spectral camouflage performance under the vegetation background. SUMMARY
[0005] The present application aims to overcome the problems in the prior art that the bionic camouflage material has low spectral matching degree in the visible-near infrared band, is difficult to simultaneously reproduce typical spectral characteristics such as green reflection peak, red light absorption valley, red edge, high reflection platform and water absorption valley, and has insufficient light stability and complex process, and provides a preparation method of a bionic camouflage film with plant leaf visible-near infrared reflectance spectral characteristics. By selecting polyvinyl alcohol as a film-forming matrix and reasonably compounding various pigments, the reflectance curve of the obtained film material in the 300-2500 nm band is highly similar to the reflectance curve of osmanthus leaf, thereby improving the full-band spectral camouflage capability of the target in the plant leaf background environment.
[0006] The present application first provides a bionic camouflage film with plant leaf visible-near infrared reflectance spectral characteristics, which comprises, by volume percentage, 96-98% of polyvinyl alcohol and 2-4% of pigment powder; the pigment powder is composed of iron yellow powder, ultramarine powder, alizarin green powder and copper-chromium black powder.
[0007] Further, in the bionic camouflage film with plant leaf visible-near infrared reflectance spectral characteristics, by volume percentage, the pigment powder comprises 1.2-2.5% of iron yellow powder, 0.35-0.8% of ultramarine powder, 0.35-0.75% of alizarin green powder and 0.01-0.02% of copper-chromium black powder.
[0008] The present application secondly provides a preparation method of a bionic camouflage film with plant leaf visible-near infrared reflectance spectral characteristics, which comprises the following specific steps: Step one, preparation of polyvinyl alcohol solution: mix polyvinyl alcohol with deionized water, heat and stir until the polyvinyl alcohol is completely dissolved, and obtain a clear and transparent polyvinyl alcohol solution; Step two, preparation of pigment dispersion slurry: weigh the iron yellow powder, ultramarine powder, alizarin green powder and copper-chromium black powder according to the volume fraction ratio of the target formula, mix the four kinds of pigment powders, add anhydrous ethanol, and obtain a uniform pigment dispersion slurry by ultrasonic dispersion; Step three, preparation of casting solution and defoaming: add the pigment dispersion slurry obtained in step two to the polyvinyl alcohol solution obtained in step one, heat and stir until the mixed pigment slurry is completely dispersed in the polyvinyl alcohol matrix, and then defoam the casting solution; Step four, casting, drying, demolding and obtaining the bionic camouflage film: cast the defoamed casting solution of step three on a flat substrate, dry the substrate in a constant temperature drying oven, and obtain the bionic camouflage film by peeling off the obtained film after the water is basically removed.
[0009] Further, the heating temperature in step one is 80-95 DEG C, the stirring speed is 300-500 r / min, the stirring time is 1-3 h, and the mass percentage of polyvinyl alcohol in the solution is 9-11%; further, the volume percentage of polyvinyl alcohol in the finally obtained biomimetic camouflage film is 96-98% by controlling the addition amount of raw materials.
[0010] Further, the total volume percentage of iron yellow powder, ultramarine powder, alizarin green powder and copper-chromium black powder in the finally obtained biomimetic camouflage film is 2-4% by controlling the addition amount of raw materials in step two; the concentration of pigment powder in the pigment dispersion slurry is 0.75-1.56 wt%; and the ultrasonic dispersion time in step two is 5-10 min.
[0011] Further, the volume percentage of iron yellow powder in step two is preferably 1.2-2.5%; the volume percentage of ultramarine powder in step two is preferably 0.35-0.8%; the volume percentage of alizarin green powder is preferably 0.35-0.75%; and the volume percentage of copper-chromium black powder is preferably 0.01-0.02%.
[0012] Further, the heating temperature in step three is preferably 25-35 DEG C, the stirring speed is preferably 300-500 r / min, and the stirring time is preferably 0.5-1 h.
[0013] Further, the liquid layer thickness of the casting solution cast on the flat substrate in step four is preferably 1-2 mm, the heating temperature of the constant-temperature drying oven is preferably 50-60 DEG C, and the heating time is preferably 6-8 h.
[0014] The biomimetic camouflage film prepared by the above method has a plant leaf visible light-near infrared reflective spectrum characteristic, and the thickness is 0.1-0.2 mm.
[0015] The biomimetic camouflage film prepared by the present application is subjected to reflectivity test in the 300-2500 nm wave band with osmanthus leaf, and the similarity of the reflectivity curves of the two is evaluated by correlation coefficient. The test results show that the biomimetic camouflage film prepared by the above formula and process conditions has a correlation coefficient of reflectivity curve with osmanthus leaf not less than 0.96 in the 300-2500 nm wave band, can simultaneously present the green peak, red light absorption valley, red edge, high reflection platform and water absorption valley characteristics of osmanthus leaf, and realize the same color and same spectrum biomimetic camouflage effect from visible light to near infrared wave band.
[0016] Compared with the prior art, the present application has the following beneficial effects: (1) The present application realizes the overall simulation of the visible light-near infrared reflectance spectrum of osmanthus leaf by the synergistic effect of polyvinyl alcohol matrix and pigments such as iron yellow, ultramarine blue, alizarin green and copper-chromium black, so that the correlation coefficient of the reflectance curve of the bionic camouflage film in the 300-2500nm wave band with the osmanthus leaf is not less than 0.96, and the spectral camouflage performance on the target in the evergreen plant leaf background environment can be realized.
[0017] (2) The present application uses polyvinyl alcohol as the film-forming matrix, and cooperates with the conventional dissolving, ultrasonic dispersion, stirring mixing and casting drying process, so that the bionic camouflage film with smooth surface can be obtained, the process flow is simple, the conditions are mild, and the large-scale preparation is facilitated.
[0018] (3) The pigments such as iron yellow, ultramarine blue, alizarin green and copper-chromium black selected by the present application are common pigments, the raw materials are widely available and low in cost, and have good light stability, avoiding the problems of easy aging and difficult storage of natural chlorophyll materials, and being suitable for outdoor application.
[0019] (4) By adjusting the polyvinyl alcohol concentration, the total volume percentage of pigments and the ratio of each pigment, the preparation method of the present application has certain parameter adjustability, and under the premise of ensuring high correlation coefficient, the overall reflectance level of the film material can be optimized, providing a basis for further expanding to the spectral bionics of other evergreen plant leaves. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 is a bionic camouflage film preparation process schematic diagram with visible light-near infrared reflectance spectrum characteristics of plant leaves; Figure 2 is the reflectance graph of example 1, 2, 3 and osmanthus leaf in the 300-2500nm wave band range; Figure 3 is the reflectance graph of comparative example 1, 2, 3, 4, 5, 6 and osmanthus leaf in the 300-2500nm wave band range; Figure 4 is the correlation coefficient graph of example 1, 2, 3 and osmanthus leaf in the 300-2500nm wave band range; Figure 5 is the correlation coefficient graph of comparative example 1, 2, 3, 4, 5, 6 and osmanthus leaf in the 300-2500nm wave band range; Figure 6 is a real object graph of the bionic camouflage film with visible light-near infrared reflectance spectrum characteristics of plant leaves prepared by example 2. DETAILED DESCRIPTION
[0021] The present application will be described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.
[0022] The preparation process of the biomimetic camouflage film with the visible and near-infrared reflectance spectrum characteristics of plant leaves in the following specific embodiments is shown in the schematic diagram as Figure 1 .
[0023] The raw materials used in the following specific embodiments of the present application are as follows: Polyvinyl alcohol, molecular weight 44.05, purity 99.8%, density 1.08 g·cm -3 , purchased from Sinopharm Chemical Reagent Co., Ltd.; Iron yellow powder, density 5.24 g·cm -3 , purchased from Henan Chuanghua Chemical Products Co., Ltd.; Ultramarine powder, density 2.56 g·cm -3 , purchased from Longkou Kailefu Chemical Products Co., Ltd.; Alizarin green powder, density 1.54 g·cm -3 , purchased from Shandong Yousuo Chemical Technology Co., Ltd.; Copper chrome black powder, density 5.3 g·cm -3 , purchased from Hunan Muyang New Material Technology Co., Ltd.; Lemon yellow powder, density 2.12 g·cm -3 , purchased from Dongguan Jinjiahe Food Co., Ltd.; Phthalocyanine green powder, density 2 g·cm -3 , purchased from Shanghai Clariant Chemical Technology Co., Ltd.
[0024] All the pigment powders have a purity higher than 99% and are not further purified.
[0025] Example 1
[0026] (1) 5 g of polyvinyl alcohol was weighed and mixed with 45 g of deionized water, and placed in a three-necked flask with mechanical stirring. The mixture was stirred at 400 r / min at 90 ℃ for 2 h until the polyvinyl alcohol was completely dissolved, to obtain a clear and transparent polyvinyl alcohol solution.
[0027] (2) According to the target volume percentage ratio, the volume percentages of iron yellow powder, ultramarine powder, alizarin green powder and copper chrome black powder in the final film were 1.225%, 0.395%, 0.370% and 0.010% respectively. The corresponding masses of the four pigments were weighed, and the four pigments were fully mixed and then added with appropriate amount of anhydrous ethanol. The mixture was placed in an ultrasonic cleaner and ultrasonically dispersed for 8 min to obtain a uniform pigment dispersion slurry.
[0028] (3) Slowly add the pigment dispersion slurry of step (2) into the polyvinyl alcohol solution prepared in step (1), and stir at 400 r / min at 30°C for 0.5 h to fully disperse the mixed pigment slurry in the polyvinyl alcohol matrix, obtaining a uniform casting solution. Cool the casting solution at room temperature and let stand for 30 min to eliminate air bubbles.
[0029] (4) Pour the defoamed casting solution onto a clean glass plate placed horizontally, and control the thickness of the liquid layer to be 1.5 mm. Dry the glass plate in a constant temperature drying oven at 60°C for about 6 h, and then slowly peel off the glass plate after the water is substantially removed, obtaining a biomimetic camouflage film. The film thickness is about 0.15 mm measured by a micrometer. The volume percentage of polyvinyl alcohol in the obtained biomimetic camouflage film is 98% and the total volume percentage of the four pigments is about 2% by volume fraction calculation.
[0030] Example 2
[0031] In this example, the addition amount of iron yellow powder, ultramarine powder, alizarin green powder and copper-chromium black powder is converted by volume percentage as 1.838%, 0.592%, 0.555% and 0.015% respectively, and the corresponding mass of iron yellow powder, ultramarine powder, alizarin green powder and copper-chromium black powder is weighed and mixed thoroughly, and the remaining steps are the same as in Example 1.
[0032] Example 3
[0033] In this example, the addition amount of iron yellow powder, ultramarine powder, alizarin green powder and copper-chromium black powder is converted by volume percentage as 2.450%, 0.790%, 0.740% and 0.020% respectively, and the corresponding mass of iron yellow powder, ultramarine powder, alizarin green powder and copper-chromium black powder is weighed and mixed thoroughly, and the remaining steps are the same as in Example 1.
[0034] Comparative Example 1
[0035] In this comparative example, the addition amount of iron yellow powder, ultramarine powder, alizarin green powder and copper-chromium black powder is converted by volume percentage as 0, 0.592%, 0.555% and 0.015% respectively, and the corresponding mass of iron yellow powder, ultramarine powder, alizarin green powder and copper-chromium black powder is weighed and mixed thoroughly, and the remaining steps are the same as in Example 2.
[0036] Comparative Example 2
[0037] In this comparative example, the addition amount of iron yellow powder, ultramarine powder, alizarin green powder and copper-chromium black powder is converted by volume percentage as 1.838%, 0, 0.555% and 0.015% respectively, and the corresponding mass of iron yellow powder, ultramarine powder, alizarin green powder and copper-chromium black powder is weighed and mixed thoroughly, and the remaining steps are the same as in Example 2.
[0038] Comparative Example 3
[0039] The adding amount of the iron yellow powder, the ultramarine powder, the alizarin green powder and the copper-chromium black powder in the present comparative example is converted into 1.838%, 0.592%, 0 and 0.015% by volume percentage respectively, the corresponding mass of the iron yellow powder, the ultramarine powder, the alizarin green powder and the copper-chromium black powder is weighed and mixed thoroughly, and the remaining steps are the same as those in Example 2.
[0040] Comparative Example 4
[0041] The adding amount of the iron yellow powder, the ultramarine powder, the alizarin green powder and the copper-chromium black powder in the present comparative example is converted into 1.838%, 0.592%, 0.555% and 0 by volume percentage respectively, the corresponding mass of the iron yellow powder, the ultramarine powder, the alizarin green powder and the copper-chromium black powder is weighed and mixed thoroughly, and the remaining steps are the same as those in Example 2.
[0042] Comparative Example 5
[0043] In the present comparative example, the lemon yellow powder is used to replace the iron yellow powder, and the remaining steps are the same as those in Example 2.
[0044] Comparative Example 6
[0045] In the present comparative example, the phthalocyanine green powder is used to replace the alizarin green powder, and the remaining steps are the same as those in Example 2.
[0046] Figure 2 is the reflectivity graph of the leaf of Osmanthus fragrans and the biomimetic camouflage films of Examples 1, 2 and 3 in the wavelength range of 300-2500 nm. It can be seen from Figure 2 It can be seen that the reflectivity curves of the biomimetic camouflage films of Examples 1-3 have lower reflectivity in the blue light and red light regions, have obvious reflection peaks in the green light region, gradually increase with the increase of wavelength to form a red edge near 680 nm, have a relatively high and flat reflectivity platform in the range of 780-1300 nm, and have a water absorption valley corresponding to the leaf of Osmanthus fragrans, which is generally consistent with the spectral morphology of the leaf of Osmanthus fragrans. Among them, the reflectivity curve of Example 2 is more similar to that of the leaf of Osmanthus fragrans.
[0047] Figure 3 is the reflectivity graph of the leaf of Osmanthus fragrans and the biomimetic camouflage films of Comparative Examples 1, 2, 3, 4, 5 and 6 in the wavelength range of 300-2500 nm. It can be seen from Figure 3 It can be seen that the reflectivity curves of the biomimetic camouflage films of Comparative Examples 1-6 are obviously different from the spectral morphology of the leaf of Osmanthus fragrans.
[0048] Figure 4The figure is the correlation coefficient graph of Example 1, 2, 3 and Osmanthus fragrans leaf in the range of 300-2500 nm. The correlation coefficient of the reflectivity curve of the biomimetic camouflage film of each example and the Osmanthus fragrans leaf is not less than 0.96, wherein the correlation coefficient of Example 2 is the highest, which indicates that the polyvinyl alcohol concentration and the pigment ratio selected in the application can realize high similarity of the visible light-near infrared reflectance spectrum of the Osmanthus fragrans leaf.
[0049] Figure 5 The figure is the correlation coefficient graph of Comparative Example 1, 2, 3, 4, 5, 6 and Osmanthus fragrans leaf in the range of 300-2500 nm. The correlation coefficient of the reflectivity curve of the biomimetic camouflage film of each comparative example and the Osmanthus fragrans leaf is not more than 0.96.
[0050] Figure 6 The figure is the actual figure of the biomimetic camouflage film with the visible light-near infrared reflectance spectrum characteristics of the Osmanthus fragrans leaf prepared in Example 2; it can be seen that the biomimetic camouflage film of the application appears green under natural light, the macro color of which is close to the Osmanthus fragrans leaf, which is verified by the spectrum test results, indicating that the biomimetic camouflage film of the application has good visual camouflage effect and spectrum camouflage effect in the visible light band at the same time.
[0051] The above only describes the preferred embodiments of the application, and it should be noted that for ordinary skilled in the art, several improvements and refinements can be made without departing from the principles of the application, and these improvements and refinements should also be considered as the protection scope of the application.
Claims
1. A biomimetic camouflage film having the visible light-near infrared reflectance spectral characteristics of a plant leaf, characterized in that, The pigment powder is composed of iron yellow powder, ultramarine powder, alizarin green powder and copper-chromium black powder.
2. The biomimetic camouflage film having the visible light-near infrared reflective spectral characteristics of plant leaves according to claim 1, characterized in that, The pigment powder is composed of iron yellow powder, ultramarine powder, alizarin green powder and copper-chromium black powder.
3. The biomimetic camouflage film having the visible light-near infrared reflectance spectral characteristics of plant leaves according to claim 1 or 2, characterized in that, The correlation coefficient of the reflectivity curve of the bionic camouflage film with the reflectivity curve of the leaf of Osmanthus fragrans in the wave band of 300-2500 nm is not less than 0.96, and the bionic camouflage film has the characteristics of the leaf of Osmanthus fragrans, such as green peak, red light absorption valley, red edge, high reflection platform and water absorption valley.
4. The method for preparing a biomimetic camouflage film having the visible light-near infrared reflectance spectral characteristics of a plant leaf according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: Step one, preparing a polyvinyl alcohol solution; Step two, dispersing the pigment powder in anhydrous ethanol to obtain a pigment dispersion slurry; Step three, mixing the polyvinyl alcohol solution and the pigment dispersion slurry uniformly to obtain a casting solution, and standing and defoaming; Step four, casting, drying and demolding to obtain the bionic camouflage film.
5. The method of claim 4, wherein the method is characterized by: The mass percentage of polyvinyl alcohol in the polyvinyl alcohol solution is 9-11%.
6. The method of claim 4, wherein the method is characterized by: The concentration of the pigment powder in the pigment dispersion slurry is 0.75-1.56 wt%.
7. The method of claim 4, wherein the method is characterized by: The casting is performed by casting the casting solution on a flat substrate, and the thickness of the liquid layer is 1-2 mm.
8. The method of claim 4, wherein the method is characterized by: The drying temperature is 50-60 DEG C, and the time is 6-8 h.
9. The bionic camouflage film with the visible light-near infrared reflectivity spectrum characteristics of plant leaves according to any one of claims 1-3 is applied in spectral camouflage.
10. Use according to claim 9, characterized in that: The bionic camouflage film is used for preparing a spectral camouflage coating layer of a target surface in the background environment of plant leaves.