Study On The Preparation Of Super-hydrophilic Coating On Glass Surface Using Nano-silica With Special Morphology As Main Raw Material

In this paper,super-hydrophilic coatings with high transmittance,good hydrophilicity and good mechanical properties were designed and prepared by using nano-silica with different morphologies as the main raw materials.The specific research contents are as follows:Firstly,the technological conditions of the preparation of nano-silica sol by hydrolysis of silica fume were studied,and the factors affecting the properties of the products were investigated.The optimal conditions for the preparation of nano-silica sol by hydrolysis of silica fume were obtained through experiments.The results show that when the reaction temperature is 90? and the reaction time is 8.5 h,spherical nano-silica sol with high solid content and good stability can be prepared.Furthermore,a gelling agent was added to induce aggregation of the small particle size nano-silica to form dendritic nano-silica.The effect of the amount of gelling agent on the particle size of dendrimer nano-silica was investigated,so as to prepare dendritic nano-silica sol with different morphologies.Secondly,the effects of acid and alkali catalysts on the hydrolysis of tetraethyl orthosilicate(TEOS)were studied.It was found that the hydrolysate with long-chain structure and adhesive effect could be prepared only under acid catalyst,while nano-silica particles could be formed after TEOS hydrolysis under basic catalyst.Therefore,TEOS hydrolysate was prepared in alcohol water mixed solvent with hydrochloric acid as catalyst,which was used as the binder between nano-silica and glass substrate,and determined the optimal ratio of TEOS,ethanol,hydrochloric acid and water through experimental research.Finally,nano-silica with different morphologies was used as the main raw material,TEOS hydrolysate and additives was added to prepare the coating solution.The coating solution was coated on the surface of the glass substrate,and the super-hydrophilic coating was obtained after drying and heat treatment.Through the optimization of the process parameters,the optimal experimental conditions for the preparation of super-hydrophilic coating were obtained: the nano-silica sol and TEOS hydrolysate were evenly mixed according to the solid content ratio of 7:3,and then 10% of the total mass of ethylene glycol was added as the moisturizing agent.The pre-washed glass substrate was immersed in the coating solution,pulled at a speed of 2 mm/s.After drying and heat treatment,a super-hydrophilic coating with anti-fogging and self-cleaning properties was obtained,which has a contact angle close to 2° and a grade 0 adhesion,a hardness of 9 H.This process is simple,efficient and low-cost,which is expected to achieve large-scale industrial production.