Preparation Of Nanosilver Solution Microcapsules And Their Effects On The Properties Of Waterborne Coatings On Wood Surface

As a biological organic substance,wood is frequently damaged by insects,bacteria,and fungus and is vulnerable to deterioration like mold,which reduces its service life and restricts its range of applications.Additionally,coating treatment can successfully shield the substrate from the effects of the environment.However,in real-world settings,the coating experiences microscopic fissures brought on by mechanical outside pressures,which lessens the coating’s protective capacity.This study aims to endow the coating with antibacterial properties while further extending its service life.This study uses microcapsule technology to directly embed antibacterial and restorative chemicals in a water-based coating on the surface of the Andoung wood.To create a dual effect of antibacterial self-healing,the antibacterial agent is released from the wall material micro-pores and the core material restorative agent flows out when stress is activated.This paper focuses on the creation and optimization of nano silver solution microcapsules,followed by the research process of creating shellac self-healing microcapsules,to explore the preparation process of antibacterial self-healing dual functional coatings.The main research results are as follows:（1）The urea-formaldehyde resin（UF）coated nano-silver solution microcapsules were created using in-situ polymerization.The four parameters of W_core:W_wall,HLB value of emulsifier,W_core:W_solution,and stirring rate were used to design the orthogonal experiment.By combining the experiment’s findings with the variation and range,the HLB value of the emulsifier was found to have the greatest influence.By combining microcapsules with a 4%additive content into a water-based coating,an antibacterial coating was created.As the HLB value of the emulsifier increased,the glossiness,color difference,adhesion,impact resistance,and roughness of the paint film on the glass substrate and the Andoung wood surface showed a decreasing trend,with little impact on hardness.In addition to the mechanical,optical,and other properties of the coating,the nano silver solution microcapsule prepared on the surface of the glass substrate has 80.7%against Escherichia coli and 74.6%towards Staphylococcus aureus when the HLB value of the emulsifier is 4.97.The antibacterial activity of the coating film on the surface of the wood was 75.7%against Escherichia coli and 70.9%against Staphylococcus aureus,respectively.It has the excellent comprehensive performance.（2）Antibacterial microcapsules were using chitosan（CS）modified nano silver solution as the core material and melamine formaldehyde resin as the wall material to boost coverage rate and antibacterial properties.The concentration of emulsifiers appears to have the greatest influence on the creation of microcapsules,according to the results of orthogonal experiments.The higher the concentration of emulsifier,the higher the encapsulation rate of microcapsules,with a maximum of 44%.The higher the concentration of emulsifier,the better the morphology of microcapsules and dispersion.The higher the concentration of emulsifier,the smaller the particle size of microcapsules.In terms of optics,the higher the concentration of emulsifier,the gloss of the paint film shows a trend of first increasing and then decreasing.Emulsifier concentration is adversely connected with transmittance and has little impact on the paint film’s color difference.According to mechanics,the adhesion and roughness are adversely connected with emulsifier concentration while hardness and impact resistance of the paint film are directly proportionate to emulsifier concentration.Microcapsules with the 4%content are mixed into water-based coatings to prepare antibacterial coatings.The higher the concentration of emulsifiers,the better the antibacterial properties of the paint film.The paint film on the surface of the glass substrate has an antibacterial rate on Staphylococcus aureus and Escherichia coli of71.3%and 80%,respectively,according to the physical and chemical features of the coating.With good performance,the Andoung wood surface paint film’s antibacterial rate towards Staphylococcus aureus and Escherichia coli achieved the maximum,68.4%and 73.2%.（3）The nano silver solution and the two top antibacterial microcapsules from the previous two chapters were utilized as antibacterial agents to determine which antibacterial agent had the highest overall performance.They were coated on the surface of the Andoung wood after being loaded into the water-based coating at a rate of 1%,2%,3%,4%,5%,6%,and 7%.As the content of antibacterial agents increases,the UF@Ag NPS microcapsules have the best antibacterial performance towards Staphylococcus aureus and Escherichia coli,with antibacterial rates of 79.0%and 82.1%,respectively.The optical and mechanical properties of the coating fast worsen as the antibacterial agent addition content increases due to microcapsules.After aging,the color difference of the coating is positively correlated with the amount of antibacterial agent added.The antibacterial coating prepared by UF@Ag NPS microcapsules has a minimum color difference change of 6.5,and the antibacterial coating prepared with a 5%additive content can alleviate the aging rate of the coating.It has good optical performance and a liquid resistance level of 2.When the content of 5%was added,according to research comparing high-temperature accelerated aging and ultraviolet aging,the antibacterial activity of the coating created by UF@Ag NPS microcapsules decreased with Escherichia coli coating from 82.1%to 62.2%and decreased against Staphylococcus aureus coating from 79.3%to 61.1%,which can maintain long-term antibacterial activity.The antibacterial performance of the coating is superior to that after ultraviolet aging after high-temperature accelerated thermal aging.The chemical makeup of the coating is unchanged by the two aging processes.The nano-silver microcapsule antibacterial coating,which is made by coating nano-silver solution with urea formaldehyde resin,has effective antibacterial properties and may prevent bacterial development on its surface.（4）The nano silver solution microcapsules were mixeded with rosin modified shellac microcapsules to achieve dual functions of coating antibacterial and self-healing.The antibacterial rate was employed as the experimental outcome in orthogonal trials,and range and variance were used as the addition method to achieve the highest influencing factor.The two microcapsules were individually applied without changing the hardness of the paint layer,boosting impact strength and adhesion,and resulting in a smooth and flat coating surface as part of research into the impacts of various addition techniques on the physical and chemical properties of coatings.The self-healing microcapsules were added to the primer and antibacterial microcapsules were added to the topcoat.The hardness of coating 6#(P_sT_1a)was maintained at 3H,and the adhesion reached level 2.The impact strength reached up to 18kg·cm,and the minimum roughness was 1.144μm.The testing of the elongation at break of the paint film before and after scratching proves that the elongation at break of coating 6#(P_sT_1a)prepared by independent addition method has increased by 2.2%compared to before scratching.The shellac microcapsules can release repair agents under stress.The independent addition methods can improve the antibacterial performance of the paint film more than the mixed addition method.The coating with 6#(P_sT_1a)antibacterial rate against Escherichia coli and Staphylococcus aureus was 82%and 83.3%,respectively,while the repair rate was 41.1%.Two types of microcapsules can be independently added to water-based coatings to achieve antibacterial and self-repairing effects,with good overall performance.