Preparation And Self-repairing Performance Of Brass Powder-Waterborne Acrylic Decorative Coating On Wood Surface

Metal filler and wood waterborne coatings can be mixed to create the decorative coating with distinctive flicker,which can be used on the surface of wooden structures,furniture,and handicrafts.The service duration of the decorative coating is severely limited by its weak mechanical properties,dispersion,and compatibility characteristics.Because wood is a kind of porous heterogeneous material,it is extremely vulnerable to environmental factors.The coating on the wood surface is also more susceptible to the effects of the drying shrinkage and swelling characteristics of the wood,resulting in microcracks,leading to its loss of its decoration and protection abilities.As a result,in order to produce a uniform brass powder-waterborne acrylic decorative coating with better mechanical properties,this study chose the brass powder-waterborne acrylic decorative coating system to apply to the surface of Tilia europaea(Basswood),and it investigated the best modification procedure using silane coupling agent modification technology to increase the compatibility of the“brass powder-waterborne acrylic” inorganic-organic interface.Additionally,self-repairing microcapsules were embedded into decorative coatings.The changing trends and reasons for the impact of different parameters on coating performance were revealed.A more thorough selfrepairing decorative coating preparation process with better comprehensive performance was optimized by adjusting the coating process parameters.This work created a technical foundation for the development of metal fillers-waterborne decorative coatings for wood.The following are the primary conclusions:(1)The optical characteristics of a brass powder-waterborne acrylic coating were significantly influenced by the modified brass powder content and the type of silane coupling agent used.The higher the brass powder content,the worse the gloss and color uniformity of the coating,the more obvious the color change,the lower the visible light reflectance,the stronger the hardness and impact resistance,and the worse the adhesion,roughness,aging resistance,and liquid resistance.This is true for brass powder-waterborne acrylic coatings modified with various coupling agents.Under a coating method of “three coats of primer and two coats of topcoat”,the brass powder filler modified under the conditions of a p H value of 5 in the reaction solution and a 6% content of silane coupling agent KH570 was mixed at a 10% mass fraction into a waterborne topcoat.This prepared decorative coating for the surface of Basswood performed more effectively overall.It has the gloss of 20.0 GU,color difference of 3.12,visible light reflectance of 0.3566,color main wavelength of 590.00 nm,hardness of HB,impact resistance of 4 kg·cm,adhesion of grade 1,roughness of 1.322 μm,and outstanding resistance to liquids and aging.(2)The service life of decorative coatings was extended by introducing self-repairing functionality by microcapsule technology.By using melamine resin coated waterborne topcoat microcapsules as the repair agent,adding modified brass powder and microcapsules to the topcoat under the coating process of “three coats of primer and two coats of topcoat”,a self-repairing decorative coating was created.The content of brass powder and the core-wall ratio of the microcapsule,respectively,had a significant impact on the optical and mechanical properties of this coating.An increase in brass powder content decreased gloss,color uniformity,visible light reflectance and transmittance,adhesion,aging resistance,liquid resistance,and self-repairing performance of the coating,and improved color change,hardness,impact resistance,and roughness of the coating for brass powder-waterborne acrylic coatings containing microcapsules with different core-wall ratios.The decorative coating containing 3% microcapsules with a 0.58:1 core-wall ratio and 3% brass powder offered the best overall performance.Its gloss is 24.0 GU,color difference is2.13,color main wavelength is 587.47 nm,visible light reflectance and transmittance are 0.5879 and74.33%,respectively.Its hardness is H,impact resistance is 2 kg·cm,adhesion is grade 2,roughness is 2.600 μm.Its aging and liquid resistance is excellent,and repair rate is 19.62%.(3)The method of how microcapsules and brass powder are added significantly affects the overall effectiveness of decorative coatings.An innovative self-repairing decorative coating for Basswood surfaces was created using melamine resin coated waterborne primer microcapsules as the repair agent under the coating process of “three coats of primer,two coats of topcoat,and introducing brass powder and microcapsules into the primer”.The optical and mechanical properties of this coating were significantly impacted by the curing temperature and brass powder content,respectively.The optical qualities,mechanical properties,liquid resistance,aging resistance,and self-repairing performance of the coating improved at higher curing temperatures under varying brass powder contents.The waterborne acrylic wood coating obtained at 60 °C with 3% brass powder and 3% microcapsules provided the best all-around qualities.It has the gloss of 34.1 GU,color difference of 0.00,visible light reflectance of 0.6038,visible light transmittance of 76.20%,color main wavelength of 589.79 nm,hardness of HB,impact resistance of 2 kg·cm,adhesion of grade 1,roughness of 1.125 μm,excellent aging and liquid resistance,and repair rate of 22.93%.(4)Melamine resin coated shellac microcapsules have higher self-repairing potential in the field of the storage and protection of wooden furniture.Different self-repairing decorative coatings were created by using the coating process of "three coats of primer,two coats of topcoat,and introducing brass powder and microcapsules into the primer".The gloss and elongation at break of coatings were significantly affected by the microcapsule content and core-wall ratio.The higher the content of shellac microcapsules,the worse the gloss and color uniformity of the coating,the lower the visible light reflectance and transmittance,the higher the hardness and impact resistance,the lower the adhesion and smoothness,the worse the liquid resistance,and the higher the aging resistance and self-repairing performance.The decorative coating containing 9% microcapsules with a 0.75:1 corewall ratio and 6% brass powder has the gloss of 22.1 GU,the color difference of 2.37,the visible light reflectance of 0.4638,the color main wavelength of 587.42 nm,the visible light transmittance of 62.25%,the hardness of 4H,the impact resistance of 4 kg·cm,the adhesion of 2 grade,the roughness of 1.926 μm,excellent aging and liquid resistance,and the repair rate of 27.83%.