Study On Preparation And Properties Of Polysaccharide-Based Waterborne Interior Wall Coating

With the improvement of people's living standard and the enhancement of environmental protection awareness,the social requirements of the interior wall coating is not only to be beautiful and protective,but also to be green and environmentally friendly,harmless to the human body and friendly to the environment.Xanthan gum and locust bean gum are two kinds of different polysaccharides.They are natural renewable materials,non-toxic,harmless,abundant in resources and cheap in price.The use of polysaccharide base material instead of synthetic emulsion made from petroleum can effectively reduce the consumption of non-renewable resources.In this paper,xanthan gum and locust bean gum were used as raw materials,and the dissolution temperature and concentration of polysaccharides were screened based on viscosity,stability and film-forming performance.Then,water-soluble polymer polyvinyl alcohol was used as the composite material to improve the film forming performance of polysaccharide base material.By testing the water resistance,kinematic viscosity and water absorption of the composite system,the best model and dosage of PVA were selected.Then nanometer silica was used to modify the polysaccharide-PVA system,by comparing the properties of the modified base material,the preparation technology and optimal amount of nano-silica were screened out.Finally,the formulation of interior wall coating was optimized and the environmental protection interior wall coating was prepared which meeted national standard.The results showed that the dissolution temperature and concentration of polysaccharides had a great influence on hydrosol.The optimal dissolution temperature of xanthan gum was 40?,the optimal dissolution temperature of locust bean gum was 60?,and the optimal mass fraction of polysaccharide was 3%(locust bean gum:xanthan gum=4:6).PVA could improve the fluidity and water resistance of the base material.PVA of model 24-99 was preferred as the compound material,and the additive amount was 4%of the polysaccharide base material.The compatibility between nano-SiO2 sol and polysaccharide base material was better than that between nano-SiO2 powder and polysaccharide base material.When the addition amount of nano-SiO2 sol reached 12%,various properties of the modified base material were improved.The tensile strength of the coating film increased to 7.71 MPa,the elongation at break decreased to 53.7%,the water absorption decreased to 34.93%,the contact angle increased to 101.4°,and the transparency increased to 53%.Taking the addition amount of titanium dioxide,barium sulfate,and talc as influencing factors,and using the contrast ratio,adhesion,and hardness of the coating as evaluation indicators,an orthogonal test was designed.The results showed that the optimal dosages of titanium dioxide,barium sulfate,and talc were 28%,10%and 10%of the base material,its performance:contrast ratio 0.978,hardness 2H,adhesion 0 grade.The use of additives could significantly improve the problems of paint blistering,shrinkage,and poor stability.Polyether-modified silicone was preferred as antifoaming agent,with an added amount of 0.5%;associative polyurethane was used as leveling thickener,with an added amount of 1.6%;as the wetting and dispersing agent,0.1%anionic sodium polyacrylate+0.25%anionic sodium polyphosphate+0.23%non-ionic isomeric alcohol polyoxyethylene ether were preferred.The finished interior wall coating had excellent performance and meeted national standard.