Preparation method and application of hydrophobic hyperspectral camouflage filler

Abstract

The invention discloses a preparation method and application of a hydrophobic hyperspectral camouflage filler, and the method comprises the following steps: (1) mixing two metal salts and an organic pigment in deionized water to obtain a solution A; mixing biological polysaccharide, a structure-directing agent and a precipitator in deionized water to obtain a solution B; (2) mixing the solution A and the solution B, shearing and stirring the mixed solution by using a shearing stirrer, and aging at high temperature; (3) cleaning and drying the aged precipitate to obtain an intermediate product; and (4) adding the intermediate product into a solution containing long-chain alkyl, fully reacting, centrifuging the solution, and washing and drying the centrifuged solid to obtain the camouflage filler. According to the preparation method, the intermediate product with a wrinkle structure on the surface can be prepared, so that grafting sites of the intermediate product are improved, more hydrophobic carbon chains are grafted on the intermediate product, on one hand, the dispersity of the camouflage filler in oleoresin is improved, on the other hand, the hydrophobicity of a final camouflage coating is improved, and the camouflage coating has good anti-fog performance and weather resistance.

Description

Technical Field

[0001] The invention relates to a method for preparing a hydrophobic hyperspectral camouflage filler, and also relates to application of the camouflage filler prepared by the method in preparing an oil-based hyperspectral camouflage coating. Background Art

[0002] Hyperspectral camouflage materials need to simulate the same spectral characteristics as green vegetation, which requires starting from the chlorophyll, water, and cell structure in the leaves. The materials that simulate the effects of chlorophyll mainly include green inorganic or organic pigments, chlorophyll derivatives, etc. The materials that simulate plant water molecules and cell structures currently used mainly include hygroscopic polymers (hydrogels, polystyrene, etc.), salt materials such as (molecular sieve salts, hygroscopic salts, hydrotalcite, etc.), porous material polymers, microcapsules, hydrotalcite, etc. The above substances all have a characteristic, that is, they are difficult to dissolve in oily substances, which leads to the film-forming agents of hyperspectral camouflage fillers using water-based adhesives and water-soluble polymers to form films. Water-soluble polymers can dissolve and swell in water, resulting in poor weather resistance of the coating formed by hyperspectral camouflage coatings, resulting in poor performance during actual application. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a method for preparing a hydrophobic hyperspectral camouflage filler. The camouflage filler prepared by this method has high spectral matching with green vegetation (sycamore leaves) and good hydrophobicity, so that it can be used to prepare oil-based hyperspectral camouflage coatings, so that the formed camouflage coating has good weather resistance and can maintain good camouflage performance in a variety of climates.

[0004] Another object of the present invention is to provide the use of the camouflage filler prepared by the above method in the preparation of oil-based hyperspectral camouflage coating.

[0005] Technical solution: The method for preparing the camouflage filler of the present invention comprises the following steps:

[0006] (1) mixing two metal salts and an organic pigment in deionized water to obtain a solution A; mixing a biopolysaccharide, a structure-directing agent, and a precipitant in deionized water to obtain a solution B;

[0007] (2) Solution A and solution B are mixed, and the mixed solution is first sheared and stirred using a shear mixer, and then placed in a reactor for aging; during the shearing and stirring process, the colloidal system can better wrap the synthesized LDHs particles, which helps to obtain LHD particles with better dispersion and more uniform size;

[0008] (3) washing and drying the sheared precipitate to obtain an intermediate product;

[0009] (4) The intermediate product is added to a solution containing a long-chain alkyl group. After sufficient reaction, the solution is centrifuged, and the solid matter after centrifugation is washed and dried to obtain a camouflaged filler.

[0010] Wherein, in step (1), the two metal salts are aluminum salt and magnesium salt; wherein the molar ratio of the aluminum salt to the magnesium salt is 1:3 to 3.5.

[0011] Wherein, the aluminum salt is aluminum chloride hexahydrate; and the magnesium salt is magnesium chloride hexahydrate.

[0012] Wherein, in step (1), the organic pigments are alizarin green and acid yellow, and the mass ratio of alizarin green to acid yellow is 1:39-40.

[0013] Wherein, in step (1), the precipitant is NaOH; the structure directing agent is cetyltrimethylammonium bromide (CTAB); and the natural polysaccharide is carboxymethyl cellulose.

[0014] Among them, the added mass ratio of the precipitant to the metal salt is 2.02-2.03:1; the added mass ratio of the structure directing agent to the metal salt is 0.024-0.025:1; the added mass ratio of the carboxymethyl cellulose to the metal salt is 0.6-0.61:1.

[0015] Wherein, in step (2), the rotation speed of shear stirring is 4000-4500 r / min, and the time of shear stirring is 3-3.5 min.

[0016] Wherein, in step (3), the aging temperature is not less than 100° C., and the aging time is 8 to 9 hours.

[0017] Wherein, in step (4), the long-chain alkyl group is hexadecyltrimethoxysilane; and the mass ratio of the intermediate product to hexadecyltrimethoxysilane is 5:1 to 1.5.

[0018] Wherein, in step (4), the camouflage filler is obtained by drying at 80-85°C for 6-7h.

[0019] The camouflage filler prepared by the above method is used in the preparation of oil-based hyperspectral camouflage coating, wherein the oil-based hyperspectral camouflage coating is composed of the following components in parts by mass: 1 to 1.2 parts of camouflage filler, 0.32 to 5.2 parts of polyurethane resin, 0.16 to 2.6 parts of curing agent N-75 and 2 to 12.5 parts of organic solvent.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: the present invention can prepare an intermediate product with a wrinkled structure on the surface, thereby increasing the grafting sites of the intermediate product and enabling it to graft more hydrophobic carbon chains, thereby improving the dispersibility of the camouflage filler in the oily resin on the one hand, and improving the hydrophobicity of the final camouflage coating on the other hand, so that it has good anti-fog performance and weather resistance; the camouflage coating formed based on the camouflage coating of the present invention has a spectral similarity of up to 0.98 with green leaves (sycamore leaves) (within the 400-2500nm band), and has similar hydrophobic properties to leaves, which greatly improves the practical application value of the hyperspectral camouflage coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The reflection spectrum curve of the camouflage filler prepared in Example 1 at 400-2500nm and the spectrum curve similarity image;

[0022] Figure 2 This is a water contact angle picture of the camouflage filler prepared in Example 1;

[0023] Figure 3 This is a SEM picture of the camouflage filler prepared in Example 1;

[0024] Figure 4 The reflection spectrum curve images of the oily hyperspectral camouflage coatings prepared in Examples 2 to 5;

[0025] Figure 5 The contact angle images of the oily hyperspectral camouflage coatings prepared in Examples 2 to 5;

[0026] Figure 6 The reflection spectrum curve images of the water-based hyperspectral camouflage coatings prepared in Comparative Examples 1 to 4 are shown;

[0027] Figure 7 The contact angle images of the water-based hyperspectral camouflage coatings prepared in Comparative Examples 1 to 4;

[0028] Figure 8 The water resistance test diagram of the HCC-4 and WCC-4 coatings prepared in Example 5 and Comparative Example 4. DETAILED DESCRIPTION

[0029] Example 1

[0030] The preparation method of the hydrophobic hyperspectral camouflage filler of the present invention comprises the following steps:

[0031] (1) 0.937 g of AlCl3·6H2O, 1.537 g of MgCl2·6H2O, 0.05 g of alizarin green and 1.98 g of acid yellow were dissolved in 100 mL of deionized water to form solution A; 0.06 g of CTAB, 1.5 g of carboxymethyl cellulose and 5 g of NaOH were dissolved in 50 mL of deionized water to obtain solution B;

[0032] (2) Solution A and Solution B were mixed, and the mixture was first sheared and stirred at 4000 r / min for 3 min using a shear mixer; then the resulting solution was transferred to a reactor and aged at 100° C. for 8 h;

[0033] (3) washing the precipitate obtained after aging until the pH of the eluate is neutral, and then drying at 100° C. for 4 h to obtain the intermediate product C-LDH;

[0034] (4) Add 1 g of the intermediate product C-LDH and 0.2 mL of hexadecyltrimethylsilane to 20 mL of 75% ethanol solution and stir for 24 h;

[0035] (5) The reaction solution is centrifuged, the solid matter after centrifugation is washed, and then dried at 80° C. for 6 h to obtain a hydrophobic hyperspectral camouflage filler C-LDH-D.

[0036] Its microstructure is a uniform porous cotton-like structure, which uses a natural polysaccharide three-dimensional network structure as a template to grow a composite double-layer hydroxide of micron-sized intercalated pigment particles, and a long alkyl chain is grafted on the surface of the double-layer hydroxide.

[0037] Example 2

[0038] The method for preparing a camouflage coating based on the hydrophobic hyperspectral camouflage filler C-LDH-D prepared in Example 1 comprises the following steps:

[0039] (1) Dissolve 5.2 g of polyurethane resin in 4 mL of butyl acetate solution, stir and defoam by ultrasonication, then add 1 g of camouflage filler C-LDH-D and 2.6 g of curing agent, and finally add 10 mL of butyl acetate to adjust the viscosity of the camouflage coating;

[0040] (2) Using manual spraying technology, the spray gun pressure is 2.0-3.0 Pa, the nozzle diameter is 1.5 mm, the spraying distance is controlled at 20-25 cm, and it is sprayed on the treated substrate. After spraying, it is cured at 80°C for 3 hours to obtain the camouflage coating HCC-1.

[0041] Example 3

[0042] The method for preparing a camouflage coating based on the hydrophobic hyperspectral camouflage filler C-LDH-D prepared in Example 1 comprises the following steps:

[0043] (1) Dissolve 2 g of polyurethane resin in 2 mL of butyl acetate solution, stir and defoam by ultrasonication, then add 1 g of camouflage filler C-LDH-D and 1 g of curing agent, and finally add 5 mL of butyl acetate to adjust the viscosity of the camouflage coating;

[0044] (2) Using manual spraying technology, the spray gun pressure is 2.0-3.0 Pa, the nozzle diameter is 1.5 mm, the spraying distance is controlled at 20-25 cm, and it is sprayed on the treated substrate. After spraying, it is cured at 80°C for 3 hours to obtain the camouflage coating HCC-2.

[0045] Example 4

[0046] The method for preparing a camouflage coating based on the hydrophobic hyperspectral camouflage filler C-LDH-D prepared in Example 1 comprises the following steps:

[0047] (1) Dissolve 0.8 g of polyurethane resin in 1 mL of butyl acetate solution, stir and defoam by ultrasonication, then add 1 g of camouflage filler C-LDH-D and 0.4 g of curing agent, and finally add 2.5 mL of butyl acetate to adjust the viscosity of the camouflage coating;

[0048] (2) Using manual spraying technology, the spray gun pressure is 2.0-3.0 Pa, the nozzle diameter is 1.5 mm, the spraying distance is controlled at 20-25 cm, and it is sprayed on the treated substrate. After spraying, it is cured at 80°C for 3 hours to obtain the camouflage coating HCC-3.

[0049] Example 5

[0050] The method for preparing a camouflage coating based on the hydrophobic hyperspectral camouflage filler C-LDH-D prepared in Example 1 comprises the following steps:

[0051] (1) Dissolve 0.32 g of polyurethane resin in 1 mL of butyl acetate solution, stir and defoam by ultrasonication, then add 1 g of camouflage filler C-LDH-D and 0.16 g of curing agent, and finally add 1.5 mL of butyl acetate to adjust the viscosity of the camouflage coating;

[0052] (2) Using manual spraying technology, the spray gun pressure is 2.0-3.0 Pa, the nozzle diameter is 1.5 mm, the spraying distance is controlled at 20-25 cm, and it is sprayed on the treated substrate. After spraying, it is cured at 80°C for 3 hours to obtain the camouflage coating HCC-4.

[0053] Comparative Example 1

[0054] The intermediate product C-LDH prepared in Example 1 was used to prepare a camouflage coating, and a camouflage coating was prepared based on the camouflage coating, specifically: (1) 4 g of water-based polyurethane was dissolved in 5 mL of water, stirred and ultrasonically defoamed, and then 1 g of the intermediate product C-LDH and 1.5 g of curing agent were added thereto, and finally 2 mL of water was added to adjust the viscosity of the coating; (2) artificial spraying technology was used, with a spray gun pressure of 2.0 to 3.0 Pa, a nozzle diameter of 1.5 mm, and a spraying distance controlled at 20 to 25 cm, and the coating was sprayed on the treated substrate, and then cured at 80°C for 3 hours after spraying to obtain a camouflage coating WCC-1.

[0055] Comparative Example 2

[0056] The intermediate product C-LDH prepared in Example 1 was used to prepare a camouflage coating, and a camouflage coating was prepared based on the camouflage coating, specifically: (1) 3 g of waterborne polyurethane was dissolved in 4 mL of water, stirred and ultrasonically defoamed, and then 1 g of the intermediate product C-LDH and 1.12 g of curing agent were added thereto, and finally 1.5 mL of water was added to adjust the viscosity of the coating; (2) artificial spraying technology was used, with a spray gun pressure of 2.0 to 3.0 Pa, a nozzle diameter of 1.5 mm, and a spraying distance controlled at 20 to 25 cm, and the coating was sprayed on the treated substrate, and then cured at 80°C for 3 hours after spraying to obtain a camouflage coating WCC-2.

[0057] Comparative Example 3

[0058] The intermediate product C-LDH prepared in Example 1 was used to prepare a camouflage coating, and a camouflage coating was prepared based on the camouflage coating, specifically: (1) 2.25 g of aqueous polyurethane was dissolved in 3 mL of water, stirred and ultrasonically defoamed, and then 1 g of the intermediate product C-LDH and 0.84 g of curing agent were added thereto, and finally 1.5 mL of water was added to adjust the viscosity of the coating; (2) artificial spraying technology was used, with a spray gun pressure of 2.0 to 3.0 Pa, a nozzle diameter of 1.5 mm, and a spraying distance controlled at 20 to 25 cm, and the coating was sprayed on the treated substrate, and then cured at 80°C for 3 hours after spraying to obtain a camouflage coating WCC-3.

[0059] Comparative Example 4

[0060] The intermediate product C-LDH prepared in Example 1 was used to prepare a camouflage coating, and a camouflage coating was prepared based on the camouflage coating, specifically: (1) 1.68 g of water-based polyurethane was dissolved in 2 mL of water, stirred and ultrasonically defoamed, and then 1 g of the intermediate product C-LDH and 0.63 of the curing agent were added thereto, and finally 1 mL of water was added to adjust the viscosity of the coating; (2) artificial spraying technology was used, with a spray gun pressure of 2.0 to 3.0 Pa, a nozzle diameter of 1.5 mm, and a spraying distance controlled at 20 to 25 cm, and the coating was sprayed on the treated substrate, and then cured at 80°C for 3 hours after spraying to obtain a camouflage coating WCC-4.

[0061] Figure 1 The reflectance spectrum curve and spectrum curve similarity of the camouflage filler in Example 1 at 400-2500nm show that there are obvious water absorption valleys at 1450nm and 1930nm, which is mainly due to the presence of crystal water between the double hydroxide layers. The weakening of the water absorption peak of C-LDH-D is mainly due to the bonding of hexadecyltrimethylsilane with the surface hydroxyl group of C-LDH, which reduces the surface adsorbed water. The intermediate product C-LDH and the camouflage filler C-LDH-D have a spectrum similarity of about 0.95 with green leaves.

[0062] Figure 2 This is the water contact angle of the camouflaged filler in Example 1. It can be seen that the camouflaged powder C-LDH that has not been hydrophobically modified is hydrophilic with a water contact angle of 43.5°, while the camouflaged filler powder C-LDH-D that has been grafted with hexadecyltrimethylsilane has good hydrophobic properties with a hydrophobic angle of up to 131.1°.

[0063] Figure 3 This is the SEM picture of the camouflaged filler in Example 1. It can be seen from the figure that the hydroxy cellulose in the intermediate product C-LDH acts as a template, making the LDH sheet layer cotton-like with a higher roughness. After C-LDH-D modified with hexadecyltrimethylsilane, it can be clearly seen that its cotton-like LDH sheet is covered and the roughness is reduced.

[0064] Figure 4 The spectral curve diagrams and spectral curve similarity diagrams of the oily hyperspectral camouflage coatings of Examples 2 to 5 show that HCC-3 of Example 4 has the highest spectral similarity, which reaches 0.98972. However, HCC-4 prepared in Example 5 has a high spectral similarity and a reflectivity of 70% in the 1000-1500nm band, thereby enabling it to have stealth capabilities in actual applications.

[0065] Figure 5 The contact angles of the oily hyperspectral camouflage coatings of Examples 2 to 5 show that the contact angles are all around 100°, which is similar to the water contact angle of real leaves, greatly improving the outdoor weather resistance of the hyperspectral camouflage coatings.

[0066] Figure 6The spectral curves and spectral curve similarity diagrams of the water-based hyperspectral camouflage coatings of Comparative Examples 1 to 4 show that the similarity between the samples and the characteristic spectra of vegetation is low. The "green peak" of the coating in the visible light band of the reflection curve has a red shift, which is attributed to the fact that the water-based polyurethane is milky white, which will cause part of the color of the coating to be covered, resulting in a green peak shift in the coating. In the near-infrared wavelength range, the reflection characteristic peak of C-LDH is destroyed, causing the coating to simulate the characteristic spectral curve of green leaves to disappear. This is mainly because the water-based epoxy resin has a high polarity. These polar groups can react chemically with the hydroxyl groups on the surface of C-LDH to form covalent bonds and hydrogen bonds, causing the optical properties of the final coating to change.

[0067] Figure 7 The contact angles of the water-based hyperspectral camouflage coatings of Comparative Examples 1 to 4 show that the contact angles are all below 10°, which indicates that the coatings are extremely hydrophilic, and thus cannot be used in a wet environment.

[0068] Figure 8 The water performance test diagram of the HCC-4 and WCC-4 coatings prepared in Example 5 and Comparative Example 4 is shown in FIG. Figure 8 The leftmost picture is a real picture of acid water, alkaline water, and neutral water droplets on the coating and leaves. The droplets on the water-based coating (WCC-4) are spread out and absorbed, while the oily coating (HCC-4) and the leaves have similar hydrophobic angles. The HCC-4 and WCC-4 coatings were soaked in pure water for 5 hours. After soaking, the water soaked in the HCC-4 coating did not change color, and the water soaked in the WCC-4 coating turned green. At the same time, the HCC-4 and WCC-4 coatings were soaked in boiling water for 2 hours. After soaking, the water soaked in the HCC-4 coating did not change color, and the water soaked in the WCC-4 coating turned green. The water turns green because the stability of the organic pigment depends on the integrity of the composite material structure. When the coating begins to expand and break, the organic pigment molecules are released from the camouflage filler into the surrounding water, turning the water green and the coating faded. After being soaked in pure water, the HCC-4 coating is intact and does not fade, and has extremely high outdoor application performance.

Claims

1. A method for preparing a hydrophobic hyperspectral camouflage filler, characterized in that: The steps include: (1) mixing two metal salts and an organic pigment in deionized water to obtain a solution A; mixing a biopolysaccharide, a structure-directing agent, and a precipitant in deionized water to obtain a solution B; (2) mixing solution A and solution B, first shearing and stirring the mixture using a shear mixer, and then aging the mixture at high temperature; (3) washing and drying the aged precipitate to obtain an intermediate product; (4) The intermediate product is added to a solution containing a long-chain alkyl group. After sufficient reaction, the solution is centrifuged, and the solid matter after centrifugation is washed and dried to obtain a camouflaged filler.

2. The preparation method according to claim 1, characterized in that: In step (1), the two metal salts are aluminum salt and magnesium salt; wherein the molar ratio of the aluminum salt to the magnesium salt is 1:3 to 3.

5.

3. The preparation method according to claim 1, characterized in that: In step (1), the organic pigments are alizarin green and acid yellow, and the mass ratio of alizarin green to acid yellow is 1:39-40.

4. The preparation method according to claim 1, characterized in that: In step (1), the precipitant is NaOH; the structure directing agent is hexadecyltrimethylammonium bromide; and the natural polysaccharide is carboxymethyl cellulose.

5. The preparation method according to claim 4, characterized in that: The mass ratio of the precipitant to the metal salt is 2.02-2.03:1; the mass ratio of the structure directing agent to the metal salt is 0.024-0.025:1; and the mass ratio of the carboxymethyl cellulose to the metal salt is 0.6-0.61:

1.

6. The preparation method according to claim 1, characterized in that: In step (2), the rotation speed of the shear stirring is 4000-4500 r / min, and the shear stirring time is 3-3.5 min.

7. The preparation method according to claim 1, characterized in that: In step (3), the aging temperature is not less than 100° C., and the aging time is 8 to 9 hours.

8. The preparation method according to claim 1, characterized in that: In step (4), the long-chain alkyl group is hexadecyltrimethoxysilane; and the mass ratio of the intermediate product to hexadecyltrimethoxysilane is 5:1 to 1.

5.

9. The preparation method according to claim 1, characterized in that: In step (4), the camouflage filler is obtained by drying at 80-85° C. for 6-7 hours.

10. The use of the camouflage filler prepared by the method according to claim 1 in the preparation of oil-based hyperspectral camouflage coatings, characterized in that: The oil-based hyperspectral camouflage paint is composed of the following components in parts by mass: 1 to 1.2 parts of camouflage filler, 0.32 to 5.2 parts of polyurethane resin, 0.16 to 2.6 parts of curing agent and 2 to 12.5 parts of organic solvent.

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