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This study presents a novel method for designing and preparing a visible light-infrared-compatible camouflage sample based on the shape, size of the visible band’s color unit and the infrared band’s material coatings. The coatings were prepared by using the cold spray method on 1 m × 1 m aluminum substrates with a color unit of the regular hexagonal sample (M1) and regular quadrilateral sample (M2). Then the color difference, the temperature difference and image salience value methods were used to analyze the effectiveness of camouflage samples through the real-scene tests. The results indicate that designed and prepared compatible camouflage samples are effective in their surrounding environment. Meanwhile, it can be concluded that M1 has high fusion with a background in visible and infrared bands compared to M2, M1 has 90.6% color similarity and only 0.8% temperature difference, the M2 has 85.4% color similarity and 1.6% temperature difference with the green background. These findings indicate that the cold spray method could compensate for conventional visible light camouflage design limitations. The combination of camouflage color unit design and visible/infrared material coating could be helpful in optical camouflage research. Furthermore, to improve the military equipment’s survival time on the battlefield.

Wood surface treatment aims to improve or reduce the surface activity of wood by physical treatment, chemical treatment, biological activation treatment or other methods to achieve the purpose of surface modification. After wood surface modification, the paint film adhesion performance, gluing performance, surface wettability, surface free energy and surface visual properties would be affected. This article aims to explore the effects of different modification methods on the adhesion of wood coating films. Modification of the wood surface significantly improves the adhesion properties of the paint film, thereby extending the service life of the coating. Research showed that physical external force modification improved the hydrophilicity and wettability of wood by changing its surface structure and texture, thus enhancing the adhesion of the coating. Additionally, high-temperature heat treatment modification reduced the risk of coating cracking and peeling by eliminating stress and moisture within the wood. Chemical impregnation modification utilized the different properties of organic and inorganic substances to improve the stability and durability of wood. Organic impregnation effectively filled the wood cell wall and increased its density, while inorganic impregnation enhanced the adhesion of the coating by forming stable chemical bonds. Composite modification methods combined the advantages of the above technologies and significantly improved the comprehensive properties of wood through multiple modification treatments, showing superior adhesion and durability. Comprehensive analysis indicated that selecting the appropriate modification method was key for different wood types and application environments. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of thermochromic microcapsules on the surface coating performance of basswood board, two types of microcapsules prepared with syringaldehyde and sodium tripolyphosphate crosslinking agents were added to a UV primer and coated on the surface of basswood board. The color-change effect of the surface coating on basswood board with microcapsules added with syringaldehyde as the crosslinking agent was better than that with microcapsules added with sodium tripolyphosphate as the crosslinking agent, and the color difference varied more significantly with temperature. The effect of the two types of microcapsules on the glossiness of the surface coating on basswood board was relatively weak. The glossiness of the surface coating on basswood board with microcapsules containing syringaldehyde as the crosslinking agent showed an overall increasing trend with the increase in microcapsules, and the change trend was relatively gentle. The glossiness of the surface coating on basswood board with microcapsules containing sodium tripolyphosphate as the crosslinking agent increased first and then decreased as the amount of microcapsules added increased. The addition of microcapsules with syringaldehyde as the crosslinking agent had no significant effect on the reflectance in the visible light band of the surface coating on basswood board. Among the two groups of samples, the hardness increase in the surface coating on basswood board with syringaldehyde as the crosslinking agent was more significant. The adhesion level of the coating on the surface of the basswood board with the two microcapsules did not change. Neither of the microcapsules had a significant effect on the impact resistance of the surface on basswood board. In the comprehensive analysis, the surface coating on basswood board with microcapsules added with syringaldehyde as the crosslinking agent at a content of 4.0% had better comprehensive performance, better surface morphology, better color-change effect, and moderate mechanical properties. The color difference was found to be 21.0 at 25 °C, the reflectivity was found to be 57.06%, the hardness was found to be 3H, the adhesion was found to be five, and the impact resistance was found to be three. [ABSTRACT FROM AUTHOR]

Ultra-Violet (UV) coatings are widely adaptable of substrates and produce low emissions of volatile organic compounds. UV coatings can extend service life by adding self-healing microcapsules that restore integrity after sustaining damage. In this study, UV coating was used as a core material; microcapsules were produced and added to the UV coating to enhance its self-healing property, providing a good protection for both the UV coating and the substrate. UV primer microcapsules were prepared with UV primer as the core material and melamine formaldehyde resin as the wall material. The UV primer containing more than 98.0% solids content was mainly composed of epoxy acrylic resin, polyester acrylic resin, trihydroxy methacrylate, trimethyl methacrylate, and photo initiator. The preparation process of the UV primer microcapsules was optimized. Further, the UV coating was prepared with better UV primer microcapsules, and the effects of the UV primer microcapsules alongside the comprehensive properties of the coating were studied. The best preparation process for the UV primer microcapsules was as follows: the wall-core mass ratio was 1:0.50, Triton X-100 and Span-20 as emulsifiers with an HLB value of 10.04, the microcapsule reaction temperature was 70 °C, and the reaction time of the was 3.0 h. When the quantity of the UV primer microcapsules increased in the coating, color difference ΔE of the coating increased, gloss decreased, transmittance decreased, elongation at break increased and then decreased, roughness increased, and self-healing rate first increased and then decreased. When the addition of the UV primer microcapsules reached 2.0%, the color difference ΔE of the coating was 1.71, the gloss was 106.63 GU, the transmittance was 78.80%, the elongation at break was 3.62%, the roughness was 0.204 μm, and the self-healing rate was 28.56%, which were the best comprehensive properties of the UV primer. To improve the comprehensive properties of the UV coatings, the UV coatings were modified by a microcapsule technology, which gave the UV coatings a better self-healing property. The application range of microcapsules for the UV coatings was broadened. Based on the previous research of microcapsules in UV coatings, the results further refined the study of the effects of adding self-healing microcapsules to UV coatings using the UV coating itself as the core material. [ABSTRACT FROM AUTHOR]

The commonly used ultraviolet ray (UV) curing coatings have the characteristics of fast curing speed, high hardness, strong abrasion resistance, etc. However, the self-healing properties of UV coatings after being damaged still need to be improved. Self-healing microcapsules can alleviate this problem. The UV top coating itself has good properties, so it can be directly chosen as the core material of microcapsules. UV top coating microcapsules can be added to the UV top coating to increase the self-healing properties of the UV coating to achieve the purpose of better protection of the UV coating and fiberboards. UV top coating microcapsules were prepared and added in different contents to characterize the effect on the physical, chemical, and self-healing properties of the UV coating on a fiberboard surface. The 1#, 2#, and 3# UV top coating microcapsules that were prepared with emulsifier HLB values of 10.04, 10.88, and 11.72, respectively, were added to the UV top coating at contents of 2.0%, 4.0%, 6.0%, 8.0%, and 10.0%. The UV coatings were applied to the fiberboard using a method of two primers and two top coatings, in which no microcapsule was added in the primer, and were tested and analyzed. The results showed that when the content of microcapsules was greater than 6.0%, close to 8.0%, the excessive density of microcapsules produced stacking and extrusion between the microcapsules. As a result, the core material could not flow out smoothly when part of the microcapsule was ruptured. The outflow of the core material was not efficiently utilized, thus leading to a decrease in the self-healing rate. The 2# UV top coating microcapsules of 4.0% made the UV coatings reach the self-healing rate of 26.41%. The self-healing rate of the UV coatings prepared with the 3# UV top coating microcapsules with 6.0% was up to 26.58%. The UV coatings prepared with the 1# UV top coating microcapsules of 6.0% had the highest self-healing rate among the three groups, up to 27.32%. The UV coatings of this group had the best comprehensive properties with a chromatic aberration ΔE of 4.08, a gloss of 1.10 GU, a reflectance of 17.13%, an adhesion grade of 3, a hardness of 3H, a grade 3 of impact resistance, and a roughness of 1.677 μm. An investigation of the UV coatings on fiberboard surfaces with the content of UV top coating microcapsules can provide support for the optimization of the self-healing properties of UV coatings and can also provide innovative ideas for the preparation of the self-healing coatings on fiberboard surfaces. [ABSTRACT FROM AUTHOR]

In order to prolong the effective time of the self-healing properties of waterborne coatings containing shellac microcapsules coated with melamine rice husk powder (MRHP), three kinds of MRHPs with better microscopic morphologies, which contain 2.8% (type A), 5.5% (type B), and 8.0% (type C) of a rice husk powder (RHP), in shell materials were mixed according to three different proportions, and added to the waterborne coatings based on Tilia europaea L., under the conditions of the most proper addition amount of 6.0% microcapsules. The results indicated that the waterborne coatings containing mixed microcapsules can still maintain the best state in terms of optical properties and mechanical properties, with a chromatism of 1.10, an adhesion of zero, a hardness of 4H, an impact resistance of 7 kg·cm, and an elongation at break of 35.28%, respectively. According to the aging resistance test, the waterborne coating containing microcapsules "type A + type B + type C" demonstrated a longer effective time. After aging for 200 h in the UV climate resistance test chamber, the light loss rate at an incident angle of 60° was 2.91%. Through scratch testing, it is verified that the mixed microcapsules can prolong the self-healing time, reduce the crack size, and achieve a coating self-healing rate of 41.11%. They can also inhibit the crack growth rate to a certain extent. Roughness tests indicated that the surface roughness of the coating with mixed microcapsules increased by 0.038 μm in comparation with the single microcapsule, but the surface can still remain smooth after being covered by the topcoat without the microcapsules. Studying the ratio of mixed microcapsules provides new ideas for the optimization of a wood-based coating self-healing effect. [ABSTRACT FROM AUTHOR]

In order to achieve antibacterial properties in water-based coatings, two types of antibacterial pomelo peel flavonoid microcapsules were added to water-based coatings and decorated on the surface of fiberboard. The surface coatings of the substrates were tested and analyzed. The antibacterial rate of the surface coatings of the two groups of fiberboards gradually increased with the increase in the content of the microcapsules. The color difference of the surface coatings of both groups increased slightly, the glossiness decreased, the gloss loss rate increased greatly, and the reflectivity increased slightly. The adhesion of the surface coatings of the two groups of fiberboards did not change significantly, the roughness gradually increased, the hardness of the melamine-resin-coated pomelo peel flavonoid microcapsules gradually increased, and the impact resistance slightly improved. Compared with the antibacterial results of the coating without substrate at the same content, the antibacterial effect of the fiberboard surface coating was slightly decreased. Overall, the surface coating on the fiberboard with 9.0% chitosan-coated pomelo peel flavonoid microcapsules demonstrated superior performance, superior coating morphology, and enhanced antibacterial properties. The antibacterial rate was 73.7% against Escherichia coli, and the antibacterial rate was 77.4% against Staphylococcus aureus. The color difference was 3.85, the gloss loss rate was 90.0%, and the reflectivity was 20.19%. The hardness was HB, the adhesion was level 1, the impact resistance level was 3, and the roughness was 1.94 μm. This study explored the effect of antibacterial microcapsules on coating performance, providing a technical basis for the application of the antibacterial microcapsules. [ABSTRACT FROM AUTHOR]

Using chitosan as the shell material and Toddalia asiatica (L.) Lam extract as the core material, microcapsules of chitosan-coated Toddalia asiatica (L.) Lam extracts were prepared. The microcapsules were added to waterborne topcoats to investigate the effects of different content and MToddalia asiatica(L.) Lam extracts:Mchitosan (MT:MC) on the performance of waterborne coatings on poplar surfaces. Under different MT:MC of microcapsules, the content of microcapsules in the coating was negatively correlated with the glossiness, reflectivity, and adhesion of the coating. The addition of microcapsules reduced the liquid resistance of the coating to citric acid and improved the ethanol and cleaning agent resistance of the coating. The hardness, impact resistance, and roughness of the coatings increased gradually with the increase in microcapsule content. The content of microcapsules was positively correlated with the Escherichia coli and Staphylococcus aureus antibacterial performance of coatings, and the coatings had a slightly higher antibacterial rate against Staphylococcus aureus than Escherichia coli overall. The poplar surface coating with 5.0% microcapsules and MT:MC of 4.0:1 was excellent: the gloss was 5.30 GU, the light loss rate was 62.22%, the color difference ΔE was 22.93, the hardness was HB, the impact resistance was grade 3, the adhesion was grade 2, the roughness was 2.022 µm, the resistance to ethanol and cleaning agent was grade 2, and the resistances to Escherichia coli and Staphylococcus aureus were 74.21% and 82.01%, respectively. The results of the study provide a technical reference for the application of antibacterial waterborne coatings on wood surfaces. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) coatings are widely used because of their good performance. However, the self-healing performance of UV coatings can be further improved. Microcapsule technology can be used to solve this problem. To investigate the effects of the compound use of two UV coating microcapsules on coatings of a fiberboard surface, three kinds of UV primer microcapsules (1#, 2#, and 3# microcapsules) with different contents were added to a UV primer, and a UV top coating was prepared with UV top coating microcapsules at a consistent ratio. The UV coating was used to coat the fiberboard surface by way of a two-primer and two-top coating method. The results show that as the content of the UV primer microcapsules was increased, the self-healing rates of all three groups of coatings increased and later decreased. The color difference ΔE of coatings with the content of the UV primer microcapsules at 4.0% and top coating microcapsules at 6.0% was 3.59, the gloss was 1.33 GU, the reflectance was 21.17%, the adhesion grade was 2, the hardness was 2H, the impact resistance grade was 5, the roughness was 1.085 μm, and the self-healing rate was 30.21%. Compared with the self-healing rate of the blank control group, the increase in the self-healing rate was 10.07%, and the improvement rate was 50.00%. The comprehensive performance of the coating was better. The results provide a technical reference for the application of the UV coating microcapsules in the UV coating on fiberboard surfaces. Incorporating the self-healing UV coating microcapsules into the UV coatings and applying the UV coating microcapsules on the fiberboard surfaces supports the microcapsule technology of self-healing UV coatings, lays the foundation for extending the service life of furniture while improving the furniture's quality, and promotes the sustainable development of the coating industry. [ABSTRACT FROM AUTHOR]

Urea–formaldehyde resin was used as a wall material and Toddalia asiatica (L.) Lam extract was used as a core material to prepare urea–formaldehyde resin-coated Toddalia asiatica (L.) Lam extract microcapsules (UFRCTEMs). The effects of UFRCTEM content and the mass ratio of core-to-wall material (Mcore:Mwall) on the performance of waterborne coatings on poplar surfaces were investigated by adding microcapsules to the waterborne topcoat. Under different Mcore:Mwall of microcapsules, as the content of microcapsules increased, the glossiness and adhesion of the coatings gradually decreased, and the color difference value of the coatings gradually increased. The cold liquid resistance, hardness, and impact resistance of the coatings were all improved, and the roughness of the coatings increased. The antibacterial rates of the coatings against Escherichia coli and Staphylococcus aureus were both on the rise, and the antibacterial rate against Staphylococcus aureus was slightly higher than that against Escherichia coli. When the microcapsule content was 7.0% and the Mcore:Mwall was 0.8:1, the surface coating performance on poplar wood was excellent. The glossiness was 3.43 GU, light loss was 75.55%, color difference ΔE was 3.23, hardness was 2H, impact resistance level was 3, adhesion level was 1, and roughness was 3.759 µm. The cold liquid resistance was excellent, and resistance grades to citric acid, ethanol, and cleaning agents were all 1. The antibacterial rates against Escherichia coli and Staphylococcus aureus were 68.59% and 75.27%, respectively. [ABSTRACT FROM AUTHOR]

In order to prepare chitosan-coated pomelo peel flavonoid microcapsules with antibacterial properties, chitosan was used as the wall material for the purpose of coating the core material, pomelo peel flavonoids. The pH of the microcapsule crosslinking reaction was 7.5, the mass ratio of the microcapsule core material to the wall material was 1:1, and the concentration of the emulsifier was 1%. The microcapsules obtained under these preparation conditions exhibited superior performance, morphology, and dispersion. Additionally, the yield and coating rates were recorded at 22% and 50%, respectively. To prepare the paint film, the microcapsules were added into the coatings at varying concentrations of 0%, 3.0%, 6.0%, 9.0%, 12.0%, and 15.0%. The antibacterial efficacy of the paint film for both bacteria was progressively enhanced with the incorporation of microcapsules. The antibacterial efficacy against Staphylococcus aureus was observed to be higher than that against Escherichia coli. As the content of microcapsules increased, the color difference in the paint film increased, the gloss loss rate increased, and the light transmission rate reduced. The tensile property and elongation at break reduced, and the roughness increased. At a microcapsule content of 6.0%, the paint film exhibited superior overall performance, with an antibacterial efficacy against Escherichia coli and Staphylococcus aureus of 46.3% and 56.7%, respectively. The color difference was 38.58. The gloss loss rate was 41.0%, the light transmission rate was 90.4%, and the paint film exhibited a large elastic region, with an elongation at break of 21.5% and a roughness of 1.46 μm. [ABSTRACT FROM AUTHOR]

Antibacterial microcapsules were prepared using chitosan as the shell material and Toddalia asiatica (L.) Lam extract as the core material. The optimal preparation process for the microcapsules of Toddalia asiatica (L.) Lam extract were determined via orthogonal and single-factor experiments as follows: the mass ratio of Toddalia asiatica (L.) Lam extracts and chitosan (MT:MC) was 3.0:1, the pH value of microencapsulation was 7, and the reaction temperature was 50 °C. The MT:MC increased, the glossiness of the coatings increased and then decreased, the color difference and roughness of the coatings showed an increasing trend, the transmittance of the coatings decreased, the grade of citric acid resistance decreased, the resistance to ethanol and detergents of the coatings increased, and the fracture elongation of the coating increased and then fell. As the MT:MC of microcapsules increased, the antibacterial rates of the coating against Escherichia coli increased first, then decreased, and lastly increased. The trend of the coating against Staphylococcus aureus first increased and then decreased. When the microcapsule MT:MC was 3.0:1, the performance of the coating was better, and the antibacterial rates against the two bacteria were 67.14% and 68.39%, respectively. Toddalia asiatica (L.) Lam extracts endow waterborne coatings with antibacterial properties, expanding the application range of waterborne coatings. [ABSTRACT FROM AUTHOR]

Two types of microcapsules were added to the coating separately. The specifications of the poplar board were 50 mm × 50 mm × 8 mm. The antibacterial rate of the poplar board surface gradually increased with the increase in the microcapsule content, and the antibacterial activity for Staphylococcus aureus was slightly higher than that against Escherichia coli. Influenced by the change in the wood grain's color on the poplar board itself, both microcapsules had no significant effect on the chromaticity value and color difference of the poplar board surface, as well as the reflectance of the visible light band. The glossiness decreased with the increase in the microcapsule content, and the gloss loss rate increased with the increase in the microcapsule content. With the increase in the microcapsule content, the hardness of the poplar board surface in both groups increased slightly, and the roughness increased gradually. The adhesion of the poplar board surface coating with melamine-resin-coated pomelo peel flavonoid microcapsules was slightly reduced, and the impact resistance was not significantly affected. Chitosan-coated pomelo peel flavonoid microcapsules had no significant effect on the adhesion of the poplar board surface coating, and the impact resistance increased slightly when the content of microcapsules was higher. Comprehensively, the poplar board coating with 9.0% chitosan-coated pomelo peel flavonoid microcapsules had a better overall performance, with antibacterial activities for Escherichia coli and Staphylococcus aureus of 70.6% and 77.6%, respectively. The color difference was 6.70, the gloss loss rate was 53.9%, the reflectivity was 50.60%, the hardness was H, the adhesion was grade 1, the impact resistance was grade 2, and the roughness was 2.10 μm. The results provide technical references for the application of antibacterial microcapsules of pomelo peel flavonoids on the surface of wood materials. [ABSTRACT FROM AUTHOR]

An orthogonal experiment was designed to prepare different UV topcoat microcapsules by adjusting the mass ratio of wall material to core material, HLB value of emulsifier, reaction temperature, and reaction time of UV topcoat microcapsule. By testing the morphology and multiple properties of UV topcoat microcapsules, it was found that the biggest factor affecting the synthesis of UV topcoat microcapsules is the emulsifier HLB value. In order to further optimize the performance of UV topcoat microcapsules, a single-factor experiment was conducted with the emulsifier HLB value as the variable, and it was found that the UV topcoat microcapsules achieved the best performance when the emulsifier HLB value was 10.04. The optimal UV topcoat microcapsules were added to the UV topcoat at different amounts to prepare UV topcoat paint films. Through testing the various properties of the UV topcoat paint film, it was determined that the performance of the UV topcoat paint film was optimal when the amount of UV topcoat microcapsules added to the UV topcoat was 4.0%. The optical properties of the UV topcoat paint film were tested, and the effect of UV topcoat microcapsules on the color difference and glossiness of the UV topcoat paint film was not significant. The tensile and self-healing performance of UV topcoat microcapsules were tested. UV topcoat microcapsules can enhance the toughness of the UV topcoat paint film to a certain extent, suppress the generation of microcracks, and have a good self-healing effect. The results provide experimental support for the preparation of microcapsules using UV coatings as core materials for the self-healing of UV coatings. [ABSTRACT FROM AUTHOR]

An orthogonal experiment was conducted to prepare nine different coatings by changing four influencing factors of shellac microcapsule content, carbonyl iron powder (CIP) content, the content of carbon nanotubes (CNTs), and primer coating thickness. By testing the morphology and performance of the shellac microcapsules, CIP, CNT blended coatings (SCCBC), and using the elongation at tensile failure of the SCCBC as the orthogonal experimental analysis, it was determined that the biggest factor affecting the elongation at tensile failure of SCCBC was the shellac microcapsule content. With the aim of further optimizing the properties of the SCCBC, a single-factor experiment was performed using shellac microcapsule content as the sole variable, and it was determined that the SCCBC exhibited optimal performance when shellac microcapsule content reaches 4.2%. The optical properties of SCCBC were tested, showing that there were minor fluctuations in the glossiness and color difference of the SCCBC. The mechanical properties of SCCBC were tested. The presence of shellac microcapsules can contribute to an improvement of the SCCBC toughness, restraining the formation of microcracks, and have a certain self-healing effect. The electromagnetic wave absorption properties of the mixed powder of shellac microcapsules, CIP and CNTs were tested. The CIP and CNTs can enhance the electromagnetic wave absorption properties of the waterborne coating, but the electromagnetic wave absorption properties were weaker in low-frequency bands. The SCCBC on the surface of fiberboard not only have a self-healing effect, but also have a certain electromagnetic wave absorption function through the mixing of shellac microcapsules, CIP, and CNTs, expanding the application range of waterborne coatings for wood. [ABSTRACT FROM AUTHOR]