Effect Of Surface Treatment On Adhesion Property Of Water-based Paint Film Modified By Sodium Silicate On Poplar

With an improvement of consumption level and environmental awareness,the solid wood furniture has become popular for its Eco-friendly and health nature.However,the lack of high-quality wood resources is the main limitation of the development of solid wood furniture,artificial fast-growing woods have become the main way to alleviate the contradiction between wood supply and demand.Artificial fast-growing woods have the advantages of fast-growth rate,quick adaptability and easy processing and shaping,but they have some disadvantages of loose material,low density and easy deformation,which limits their exploiting and application.Poplar is a very popular and commonly used artificial fast-growing species.To improve the mechanical properties,flame retardancy,and smoke suppression of poplar wood,expand its application range and increase its added value,sodium silicate was used to modify the fast-growing poplar to improve the physical and mechanical properties,but adverstly affected the adhesion performance of its surface paint film.As the adhesion performance of paint film is one of the important properties of solid wood furniture,so this paper mainly takes sodium silicate modified poplar(SSMP)surface as the research object,explore the effects of surface sanding(roughness),NaOH treatment,silane coupling agent treatment,combined treatment of NaOH and silane coupling agent on film adhesion properties and visual properties of SSMP surface,which provide technical and theoretical supports for the industrial production of the poplar wood.The main contents and research results are as follows:(1)Selection of the best roughness on the basis of good film adhesion property.We used sandpapers with different granularity ranges to sand the surface of SSMP to change its surface morphology and explored the effects of roughness on the film adhesion performance of SSMP surface.The results showed that 240#sandpaper grinding SSMP surface roughness Ra value was minimum and the film adhesion property was the best(grade 2).After the same mesh number of sandpaper grinding SSMP surface,the radial and chord sections had little effect on the adhesion of the film.(2)Effects of NaOH treatment on adhesion property of the SSMP surface film.After treating the SSMP surface with NaOH solution,the overall adhesion property of the paint film was improved,and the surface wettability and surface free energy were improved to some extent.When the mass fraction of NaOH solution was 5%,the adhesion level of the film reached grade 0.(3)Effects of silane coupling agent treatment on adhesion property of SSMP surface paint film.The SSMP surface was treated with different silane coupling agents such as KH550,KH560,KH570 and KH580,and the adhesion performance was evaluated.Select the type of silane coupling agent that has the best adhesion performance of the paint film,and then the influence of the mass fraction of such silane coupling agent on the adhesion performance of the film was further investigated.The results showed that the KH560 and KH580 treatments led to better adhesion performance(grade 0),the surface wettability was good,and the surface free energy was large.when the mass fraction of KH560 was equal to 1.5%or greater than 1.5%,the film adhesion was assessed as grade 0(20%-40%)and grade 1(60%-80%),respectively,the surface free energy and wettability did not change significantly with the increase of KH560 mass fraction.(4)Effects of NaOH-KH560 treatment of SSMP surface on adhesion of film and visual properties.The results showed that the minimum NaOH-KH560 mass fraction that maximizes the film adhesion performance of the SSMP surface was 0.3%-0.6%.The surface color of SSMP was yellowish compared to that of the untreated poplar wood.Compared with modified poplar wood(sanded),the surface of modified poplar wood treated with NaOH-KH560 solution tended to be blue and red,and had little effect on glossiness,brightness,texture thickness,and texture spacing.After applying water-based varnish on the modified poplar wood treated with NaOH-KH560,compared with modified poplar(sanded),the brightness decreases,the surface turns red,the glossiness significantly increases,and the texture grayscale and background grayscale values slightly decrease,with little impact on texture thickness,and texture spacing.