A method for preparing a coating having a low infrared emissivity with a simulated green leaf green peak characteristic

Abstract

The present application relates to the field of functional camouflage coating technology, in particular to a preparation method of a coating with green leaf green peak characteristic low infrared emissivity. The preparation method comprises the following steps: washing aluminum silver paste raw material with anhydrous ethanol, drying after filtration to obtain flaky Al powder filler; mixing Prussian blue and permanent yellow according to a mass ratio of 77:23~73:27 to obtain a composite coloring pigment; adding the flaky Al powder filler and the composite coloring pigment into polyurethane resin, mixing, adding a curing agent and mixing to obtain a coating; coating the coating on the surface of a substrate, surface drying at room temperature, constant temperature curing to obtain a coating with green leaf green peak characteristic low infrared emissivity. The coating has yellow-green appearance color, and has low infrared emissivity, gloss, excellent mechanical properties and green leaf green peak characteristic. Coating the coating on the surface of various equipment such as tanks, tanks and command vehicles can make them achieve the effect of green visible light and infrared stealth.

Description

Technical Field

[0001] This invention relates to the field of functional camouflage coating technology, and in particular to a method for preparing a low infrared emissivity coating with green leaf and green peak characteristics. Background Technology

[0002] With the rapid development of modern battlefield reconnaissance technology, the integrated application of multispectral detection systems has posed a severe challenge to traditional single-band camouflage methods. The rapid development of visible light identification and infrared thermal imaging detection methods, along with the maturity of integrated technologies, have rendered conventional camouflage targets targeting single bands virtually impossible to conceal. Against this backdrop, visible-infrared compatible camouflage materials applied to the surface of military targets have become a research hotspot in the current and future field of military counter-reconnaissance.

[0003] However, existing visible light and infrared compatible camouflage technologies still face many technical challenges that urgently need to be addressed.

[0004] Firstly, conventional camouflage coatings generally have high infrared emissivity. Due to this high emissivity, the surface emissivity of ordinary camouflage fabrics is excessively high, resulting in a significant difference in infrared radiation energy between the human body and the environment, making them easily detectable under infrared thermal imaging. Achieving effective compatibility between visible light camouflage and low infrared emissivity has long been a challenge in the field of camouflage materials.

[0005] Secondly, there is an inherent conflict between low-emissivity functional fillers and visible light camouflage performance. Flake aluminum powder is currently the most commonly used functional filler in low-infrared emissivity coatings, possessing a unique advantage in low infrared emissivity. However, coatings containing flake aluminum powder have extremely high brightness, easily causing severe light pollution and reducing the visible light camouflage performance of military stealth coatings. Adding coloring pigments to reduce coating brightness and achieve color camouflage significantly increases the coating's infrared emissivity. This contradiction makes it difficult for traditional aluminum powder-filled coatings to simultaneously achieve visible light yellow-green camouflage and low infrared emissivity. Furthermore, simple mixing of aluminum powder and coloring pigments can easily lead to excessively high surface gloss in the coating, further compromising the camouflage fusion effect in the visible light band.

[0006] Third, it is difficult to optimize the mechanical properties and camouflage function of the coating in a coordinated manner. In the pursuit of low infrared emissivity and visible light camouflage effects, excessive addition or improper ratio of pigments and fillers often leads to problems such as decreased coating adhesion, reduced flexibility, and insufficient impact resistance. As the outer protective layer of equipment, camouflage coatings not only need excellent optical stealth performance, but also must possess good mechanical stability and service reliability to meet the application requirements of actual battlefield environments.

[0007] In summary, how to achieve a yellow-green appearance and low gloss characteristics resembling green leaves while maintaining a low infrared emissivity of the coating, and also taking into account excellent mechanical properties, has become a core technical problem that urgently needs to be solved in the field of camouflage coatings compatible with both visible and infrared wavelengths. Summary of the Invention

[0008] To address the shortcomings of the existing technology, this invention aims to provide a composite camouflage coating and its preparation method that combines the spectral characteristics of green leaves and green peaks, low infrared emissivity, low gloss, and excellent mechanical properties.

[0009] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of this invention is a method for preparing a low infrared emissivity coating with green leaf and green peak characteristics, comprising the following steps: The aluminum silver paste raw material was washed with anhydrous ethanol, filtered, and dried to obtain sheet-like Al powder filler. Prussian blue and permanent yellow are mixed at a mass ratio of 77:23 to 73:27 to obtain a composite coloring pigment. After adding flake Al powder filler and composite coloring pigment to polyurethane resin and mixing them evenly, a curing agent is added and mixed evenly to obtain a coating. The coating is applied to the surface of the substrate, dried at room temperature, and then cured at a constant temperature to obtain the low infrared emissivity coating with green leaf and green peak characteristics.

[0010] In a preferred embodiment of the present invention, when preparing the sheet-like Al powder filler, the drying temperature is 20~35 ℃ and the drying time is 3~4 hours.

[0011] In a preferred embodiment of the present invention, the amount of the flake Al powder filler and the composite coloring pigment added is 40% to 70% of the mass of the polyurethane resin.

[0012] In a preferred embodiment of the present invention, the content of the flake Al powder filler is 10% to 17% of the total mass of the flake Al powder filler and the composite coloring pigment.

[0013] The second technical solution of the present invention is a low infrared emissivity coating (hereinafter referred to as: composite coating) with green leaf and green peak characteristics prepared by the above preparation method.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses Prussian blue and permanent yellow in a specific mass ratio as coloring pigments. The two work synergistically, with the inorganic rigid Prussian blue particles and the organic aggregated permanent yellow microcrystals forming a micro-uneven structure on the coating surface. This causes the incident light to be mainly diffusely reflected, effectively reducing the coating gloss (as low as 4.9) while achieving the yellow-green characteristics of green leaves (strong reflection peak at 539 nm), improving the visible light stealth effect, and solving the problem of poor camouflage integration caused by the specular reflection of traditional coatings.

[0015] 2. A method of washing aluminum silver paste with anhydrous ethanol and then filtering and drying for 3-4 hours is used to obtain flake-shaped Al powder filler, which can maintain the coating with a low emissivity (below 0.7) and reduce the coating gloss (below 8.5).

[0016] 3. By optimizing the amount of flake aluminum powder added (15% of the total pigment and filler content), it is evenly dispersed in the polyurethane matrix without obvious agglomeration, forming a continuous flake stacked structure, which effectively reduces the emissivity of the coating in the 8~14 μm infrared band (as low as 0.482), and the infrared radiation suppression efficiency against a 215℃ heat source reaches 31.7%, while also taking into account infrared stealth performance.

[0017] 4. Controlling the total pigment and filler content ensures that Prussian blue, permanent yellow, and flake aluminum powder are evenly dispersed in the polyurethane matrix, with good compatibility with the resin matrix. This results in excellent coating mechanical properties (adhesion grade 1, flexibility 3mm, impact strength 45kg.cm), stable structure, and resistance to peeling, cracking, and long service life.

[0018] 5. The preparation process is simple, requiring no complex equipment or harsh reaction conditions. It can be completed using conventional stirring, coating, and curing processes, resulting in low production costs and enabling large-scale industrial production.

[0019] 6. The coating has both visible light and infrared stealth properties, and its green leaf-like color characteristics are obvious, blending well with the natural background. It has broad application prospects in the design of multi-spectral camouflage coatings for various land equipment. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 These are photographs showing the appearance of the composite coatings prepared in Examples 1-5 of the present invention.

[0022] Figure 2The images show the reflection spectra of the composite coatings prepared in Examples 1-5 of this invention.

[0023] Figure 3 These are infrared thermal imaging images of the low infrared emissivity coatings with green peak characteristics prepared in Examples 1-5 of this invention. Detailed Implementation

[0024] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0025] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0026] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0027] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0028] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0029] Prussian blue, with the molecular formula Fe4[Fe(CN)6]3, is a face-centered cubic perovskite-type metal cyanide with macroscopically interconnected pores, open ion channels, and a vast pore space. Permanent yellow, a diazo organic pigment, forms needle-like or rod-like microcrystals through hydrogen bonds and π-π stacking between molecules, making it difficult for particles to form a smooth, continuous surface. When the two are mixed, the inorganic rigid particles and the organic aggregated microcrystals together constitute a microscopic uneven structure on the coating surface, causing incident light to be predominantly diffusely reflected, making specular reflection difficult. This is expected to give the green coating a low-gloss matte effect, which is beneficial for improving visible light stealth performance. Using aluminum powder as a functional filler, allowing the coating to maintain low emissivity while possessing green leaf-like green peak spectral characteristics, is an effective way to solve the above problems.

[0030] To achieve a coating with good low infrared emissivity while also possessing a yellow-green appearance, low gloss, and green leaf-like peak characteristics, this invention uses polyurethane (PU) as a binder, flake Al powder as a functional filler, and Prussian blue and permanent yellow as coloring pigments to design and prepare a low infrared emissivity coating with green leaf-like peak characteristics.

[0031] The first aspect of this invention provides a method for preparing a low infrared emissivity coating with green leaf and green peak characteristics, comprising the following steps: The aluminum silver paste raw material was washed with anhydrous ethanol, filtered, and dried to obtain sheet-like Al powder filler. Prussian blue and permanent yellow are mixed at a mass ratio of 77:23 to 73:27 to obtain a composite coloring pigment. After adding flake Al powder filler and composite coloring pigment to polyurethane resin and mixing them evenly, a curing agent is added and mixed evenly to obtain a coating. The coating is applied to the surface of the substrate, dried at room temperature, and then cured at a constant temperature to obtain the low infrared emissivity coating with green leaf and green peak characteristics.

[0032] In this invention, iron blue and permanent yellow are used as coloring pigments, polyurethane resin (PU) is used as an adhesive, and polyether polyol is used as a curing agent.

[0033] In a preferred embodiment of the present invention, when preparing the sheet-like Al powder filler, the drying temperature is 20~35 ℃ and the drying time is 3~4 hours.

[0034] In a preferred embodiment of the present invention, the particle size of the sheet-like Al powder filler is 20~50 μm.

[0035] In a preferred embodiment of the present invention, the amount of the flake Al powder filler and the composite coloring pigment added is 40% to 70% of the mass of the polyurethane resin.

[0036] In a preferred embodiment of the present invention, the content of the flake Al powder filler is 10% to 17% of the total mass of the flake Al powder filler and the composite coloring pigment.

[0037] In a preferred embodiment of the present invention, the solid content of the polyurethane resin is 60% to 70%.

[0038] In a preferred embodiment of the present invention, the curing agent is a polyether polyol curing agent, and the amount of curing agent added is 25% of the resin solids mass.

[0039] In a preferred embodiment of the present invention, the coating further includes a diluent; the diluent is anhydrous ethanol; and the amount of diluent added is such that the coating flows continuously downward in a straight line. The purpose of adding the diluent is to adjust the viscosity of the coating so that it can flow continuously downward in a straight line.

[0040] In a preferred embodiment of the present invention, the surface drying time at room temperature is 3 to 7 hours, and the constant temperature curing temperature is 80 to 100 ℃ for 8 to 10 hours.

[0041] In a preferred embodiment of the present invention, before applying the coating to the substrate surface, a pretreatment step is further included: grinding the substrate to a surface roughness of 3~10 μm, cleaning and drying it.

[0042] A second aspect of the present invention provides a low infrared emissivity coating with green leaf and green peak characteristics prepared by the above-described preparation method.

[0043] The coating prepared by this invention has a yellow-green appearance while also possessing low infrared emissivity, gloss, excellent mechanical properties, and green leaf-like green peak characteristics. Applying it to the surfaces of various equipment such as tanks, armored vehicles, and command vehicles can achieve both visible light and infrared stealth, realizing dual stealth in both visible and infrared bands.

[0044] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0045] The aluminum silver paste raw materials used in this embodiment of the invention were purchased from Shandong Yinjian Metal Pigment Co., Ltd., with the following main parameters: solid content 67%, particle size 20~50 μm; Permanent Yellow (diazo organic pigment) was purchased from Anhui Jundun New Material Technology Co., Ltd., with the following main parameters: particle size 800 mesh, purity 99.9%; Prussian Blue was purchased from Anhui Jundun New Material Technology Co., Ltd., with the following main parameters: particle size 800 mesh, purity 99.9%; polyurethane resin was purchased from Anhui Jundun New Material Technology Co., Ltd., with a solid content of 66.7%; and polyether polyol curing agent was purchased from Anhui Jundun New Material Technology Co., Ltd., with a molecular weight of 1600~1800 and a solid content of 33.2%.

[0046] The testing method involved in this invention: The emissivity of the composite coating prepared in this invention was measured in the 8-14 μm band using an IR-2 dual-band infrared emissivity meter developed by the Shanghai Institute of Technical Physics, Chinese Academy of Sciences. The gloss of the coating was measured using a JKGZ-60 specular gloss meter manufactured by Tianjin Jingkelian Materials Testing Machine Co., Ltd. The presence of a green characteristic peak resembling green leaves in the 530-540 nm band was determined using a UV-3600 UV-Vis-NIR spectrophotometer manufactured by Shimadzu Corporation. The adhesion of the coating was measured using a QFH cross-cut tester; the flexibility of the coating was measured using a QTY-10A cylindrical bending tester; and the impact strength of the coating was measured using a QCJ impact strength tester.

[0047] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0048] Example 1 This embodiment provides a method for preparing a low infrared emissivity coating (hereinafter referred to as: composite coating) with green leaf and green peak characteristics, the steps of which are as follows: Step 1, substrate pretreatment: Select a standard tinplate sheet (7 cm × 13 cm, thickness 0.3 mm) as the substrate, sand it with sandpaper until the surface roughness is 3~10 μm, rinse it with tap water, dry it in an 80℃ oven for 30 min, take it out and wipe it clean with a cotton cloth soaked in anhydrous ethanol, and set it aside.

[0049] Step 2, Preparation of flake Al powder: The aluminum silver paste raw material is washed three times with anhydrous ethanol, filtered with filter paper, dried at 30 ℃ for 4 hours, ground and sieved to obtain flake Al powder filler with a particle size of 20~50 μm.

[0050] Step 3, color pigment compounding: Prussian blue and permanent yellow (diazo organic pigment) are accurately weighed and mixed at a mass ratio of 75:25 to obtain a composite color pigment.

[0051] Step 4, Coating Preparation: Using polyurethane resin (66.7% solids content) as the matrix, the total amount of pigments and fillers (flaky Al powder + Prussian blue + permanent yellow) is fixed at 50% of the resin mass, of which the amount of flaky Al powder added is 13% of the total pigments and fillers mass. Mix the above-mentioned flaky Al powder, composite coloring pigments and polyurethane resin evenly, then add 25% of the resin mass of polyether polyol curing agent, and continue stirring until the coating is smooth and delicate.

[0052] Step 5, coating and curing: Using the glass rod coating method, weigh 1.0 g of the above coating and evenly coat it on the surface of the pretreated substrate. Let it dry at room temperature for 5 h, and then place it in an 80 ℃ oven for constant temperature curing for 10 h to obtain the composite coating.

[0053] The composite coating prepared in this embodiment possesses excellent comprehensive performance, stable mechanical properties, adhesion grade 1, flexibility of 3 mm, and impact resistance of 45 kg·cm. The coating has an emissivity of 0.693 in the 8-14 μm infrared band, providing good basic infrared stealth performance. The coating has a low gloss of 8.4, which can effectively suppress visible light specular reflection and reduce the risk of optical exposure of the target. The coating exhibits a strong yellow-green characteristic reflection peak at a wavelength of 536 nm, and its spectral characteristics are consistent with the camouflage requirements of green vegetation. The pigments are uniformly dispersed within the coating without obvious agglomeration defects, and the coating structure is dense and stable, achieving a preliminary stealth effect that is compatible with both visible and infrared light.

[0054] Example 2 The only difference from Example 1 is that in step 2, the drying time is 3.5 hours; in step 4, the total amount of pigments and fillers (flaky Al powder + Prussian blue + permanent yellow) is fixed at 55% of the resin mass, and the amount of flaky Al powder added is 14% of the total amount of pigments and fillers; the remaining steps and parameters are the same as in Example 1.

[0055] In this formulation system, the flake-like aluminum powder can be uniformly dispersed in the polyurethane resin matrix, forming a regular and continuous flake-like stacked structure. The organic matrix can completely encapsulate the pigment and aluminum powder particles, resulting in tight interfacial bonding without obvious agglomeration or phase separation defects. The coating surface is smooth, dense, and has moderate roughness. Performance test results show that the coating has excellent mechanical properties, maintaining excellent indicators such as Grade 1 adhesion, 3mm flexibility, and 45kg·cm impact strength. In the visible light band, it exhibits a stable yellow-green characteristic reflection peak at 539nm, demonstrating significant color camouflage characteristics. The coating gloss is as low as 4.5; the infrared emissivity in the 8~14μm range is as low as 0.482, and the infrared radiation suppression efficiency against a 215℃ heat source can reach 31.7%, significantly improving infrared stealth performance. At the same time, it avoids problems such as coating whitening, decreased mechanical properties, and weakened spectral characteristics caused by high aluminum powder doping, achieving a balanced match between mechanical properties, visible light camouflage, and low infrared emissivity.

[0056] Example 3 The only difference from Example 1 is that in step 2, the drying time is 3 hours; in step 4, the total amount of pigments and fillers (flaky Al powder + Prussian blue + permanent yellow) is fixed at 60% of the resin mass, and the amount of flaky Al powder added is 15% of the total amount of pigments and fillers; the remaining steps and parameters are the same as in Example 1.

[0057] Under this formulation, the pigments and fillers are uniformly dispersed in the resin matrix, without particle agglomeration, coating cracking, or structural looseness defects. The coating surface roughness is moderate, further enhancing the yellow-green vegetation camouflage color characteristics. The intensity of the characteristic reflection peak at 530nm in the visible and near-infrared bands is stable, indicating good camouflage adaptability. The coating achieves good overall performance, maintaining excellent mechanical properties such as Grade 1 adhesion, 3mm flexibility, and 45kg·cm impact strength, with good structural stability and service reliability. The coating gloss is as low as 4.9, with a significant matte effect in the visible light range, effectively avoiding optical detection and identification. The emissivity in the 8~14μm infrared band is 0.504, exhibiting excellent low infrared emission characteristics and infrared radiation suppression capabilities. It can simultaneously meet the dual-band compatibility requirements of visible light camouflage and infrared stealth for land-based equipment, demonstrating good overall application performance.

[0058] Example 4 The only difference from Example 1 is that in step 4, the total amount of pigments and fillers (flaky Al powder + Prussian blue + permanent yellow) is fixed at 65% of the resin mass, and the amount of flaky Al powder added is 16% of the total amount of pigments and fillers; the remaining steps and parameters are the same as in Example 1.

[0059] With this formulation, the coating exhibits stable intensity of the 538nm characteristic reflection peak in the visible and near-infrared bands, demonstrating good camouflage adaptability. The coating achieves excellent overall performance, maintaining superior mechanical properties such as Grade 1 adhesion, 3mm flexibility, and 45kg·cm impact resistance, resulting in excellent structural stability and service reliability. The coating's gloss level is as low as 5.3, providing a significant matte finish in the visible light spectrum, effectively evading optical detection and identification. With an emissivity of 0.489 in the 8~14μm infrared band, it possesses excellent low infrared emission characteristics and infrared radiation suppression capabilities, simultaneously meeting the dual-band compatibility requirements for visible light camouflage and infrared stealth in land-based equipment, resulting in optimal overall application performance.

[0060] Example 5 The only difference from Example 1 is that in step 4, the total amount of pigments and fillers (flaky Al powder + Prussian blue + permanent yellow) is fixed at 70% of the resin mass, and the amount of flaky Al powder added is 17% of the total amount of pigments and fillers; the remaining steps and parameters are the same as in Example 1.

[0061] With this formulation, the coating exhibits stable intensity of the 536nm characteristic reflection peak in the visible and near-infrared bands, demonstrating good camouflage adaptability. The coating achieves good overall performance, maintaining excellent mechanical properties such as Grade 1 adhesion, 3mm flexibility, and 45kg·cm impact strength, resulting in good structural stability and service reliability. The coating's gloss level is as low as 4.7, providing a significant matte finish in the visible light spectrum, effectively evading optical detection. With an emissivity of 0.496 in the 8~14μm infrared band, it possesses excellent low infrared emission characteristics and infrared radiation suppression capabilities, simultaneously meeting the dual-band compatibility requirements for visible light camouflage and infrared stealth in land-based equipment, demonstrating good overall application performance.

[0062] Figure 1 These are photographs of the composite coatings prepared in Examples 1-5 of the present invention (from left to right: Example 1, Example 2, Example 3, Example 4, Example 5). Figure 1 It can be seen that as the total amount of pigments and fillers in the coating increases, the color of the coating can change from yellowish-green to a significant yellowish-green, which meets the design requirements.

[0063] Figure 2 The figures show the reflectance spectra of the composite coatings prepared in Examples 1-5 of this invention (in the figures, 13%~17% respectively represent the percentage of the amount of flake Al powder added in Examples 1 to 5 relative to the total mass of pigments and fillers). Figure 3 ).Depend on Figure 2 It can be seen that all coatings have significant green peaks at wavelengths of 536–540 nm, indicating that the coatings have obvious green characteristics.

[0064] Figure 3 These are infrared thermal imaging images of the low infrared emissivity coatings with green peak characteristics prepared in Examples 1-5 of this invention. Figure 3 It can be seen that the apparent temperature of the coating is significantly lower than the temperature of the heat source on the heating platform (215℃), demonstrating the coating's significant infrared radiation control effect on the high-temperature heat source.

[0065] Comparative Example 1 The only difference from Example 2 is that in step 3, the mass ratio of Prussian blue to permanent yellow is 85:15; the other steps and parameters are the same as in Example 1.

[0066] Coating performance test results: Mechanical properties: Excellent indicators of Grade 1 adhesion, 3mm flexibility, and 45kg·cm impact strength; The visible light band shows a stable green characteristic reflection peak at 515nm, which is significantly different from the reflection peak of green leaves; The coating gloss is as low as 5.2; The infrared emissivity of 8~14μm is as low as 0.523.

[0067] Comparative Example 2 The only difference from Example 2 is that in step 3, the mass ratio of Prussian blue to permanent yellow is 70:30; the other steps and parameters are the same as in Example 1.

[0068] Coating performance test results: Mechanical properties: Excellent indicators of Grade 1 adhesion, 3mm flexibility, and 45kg·cm impact strength; The visible light band shows a stable green characteristic reflection peak at 563nm, which is significantly different from the reflection peak of green leaves; The coating gloss is as low as 5.8; The infrared emissivity of 8~14μm is as low as 0.497.

[0069] Comparative Example 3 The only difference from Example 2 is that in step 4, the amount of flake Al powder added is 6% of the total pigment and filler mass; the other steps and parameters are the same as in Example 1.

[0070] Coating performance test results: Mechanical properties: good indicators of Grade 1 adhesion, 3mm flexibility, and 40kg·cm impact strength; the visible light band shows a stable green characteristic reflection peak at 539nm, which matches the reflection peak of green leaves; the coating gloss is as low as 3.8; but the infrared emissivity of 8~14μm is as high as 0.756.

[0071] Comparative Example 4 The only difference from Example 2 is that in step 4, the amount of flake Al powder added is 25% of the total pigment and filler mass; the remaining steps and parameters are the same as in Example 1.

[0072] Coating performance test results: Mechanical properties: Excellent indicators of Grade 1 adhesion, 3mm flexibility, and 45kg·cm impact strength; The visible light band shows a stable green characteristic reflection peak at 539nm, which matches the reflection peak of green leaves; The infrared emissivity of 8~14μm is as low as 0.275; But the coating gloss is as high as 18.6.

[0073] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a low-infrared emissivity coating with green leaf and green peak characteristics, characterized in that, Includes the following steps: The aluminum silver paste raw material was washed with anhydrous ethanol, filtered, and dried to obtain sheet-like Al powder filler. Prussian blue and permanent yellow are mixed at a mass ratio of 77:23 to 73:27 to obtain a composite coloring pigment. After adding flake Al powder filler and composite coloring pigment to polyurethane resin and mixing them evenly, a curing agent is added and mixed evenly to obtain a coating. The coating is applied to the surface of the substrate, dried at room temperature, and then cured at a constant temperature to obtain the low infrared emissivity coating with green leaf and green peak characteristics.

2. The preparation method according to claim 1, characterized in that, When preparing the sheet-like Al powder filler, the drying temperature is 20~35 ℃ and the drying time is 3~4 hours; the particle size of the sheet-like Al powder filler is 20~50 μm.

3. The preparation method according to claim 1, characterized in that, The amount of the flake Al powder filler and the composite coloring pigment added is 40% to 70% of the mass of the polyurethane resin.

4. The preparation method according to claim 1, characterized in that, The content of the flaky Al powder filler is 10% to 17% of the total mass of the flaky Al powder filler and the composite coloring pigment.

5. The preparation method according to claim 1, characterized in that, The solid content of the polyurethane resin is 60%~70%.

6. The preparation method according to claim 1, characterized in that, The curing agent is a polyether polyol curing agent, and the amount of curing agent added is 25% of the resin solids mass.

7. The preparation method according to claim 1, characterized in that, The coating also includes a diluent; the diluent is anhydrous ethanol; the amount of diluent added is such that the coating flows continuously downward in a straight line.

8. The preparation method according to claim 1, characterized in that, The surface drying time at room temperature is 3-7 hours, and the constant temperature curing temperature is 80-100 ℃ for 8-10 hours.

9. The preparation method according to claim 1, characterized in that, Before applying the coating to the substrate surface, the process includes a pretreatment step for the substrate: grinding the substrate to a surface roughness of 3~10 μm, cleaning, and drying.

10. A low infrared emissivity coating with green leaf and green peak characteristics prepared by the preparation method according to any one of claims 1 to 9.

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