Preparetion And Characterization Of Polyacrylate/nano-SiO₂ Coating

Nano-coatings have many excellent properties that other materials can not replace. Because high surface energy and hydrophilic properties of nano-SiO₂ the application in nano-coatings is restricted.In this article,description relating to the history of development of nanomaterials was viewed.It also be summarized that about preparation methods and characteristics. Then the properties of nano-SiO₂,methods of modified nano-SiO₂ and application of nano-SiO₂ were discussed.The surface of the nano-SiO₂ was modified withγ-glycidoxypropyltrimethoxy -silane.Then polyacrylate/nano-SiO₂ composite resins were prepared via in situ polymerization or blending method.Hydroxyl value,acid value and solid content of the composite resins were determined.The turbidity and viscosity of the two kinds of the composite resins were acquired by turbidimeter and rotational viscometer.The composite resins obtained from in situ polymerization were investigated by Fourier-transform infrared spectroscopy(FTIR) and Differential scanning calorimetry (DSC).FTIR analysis showed that in situ polymerization provoked grafting reactions between polyacrylate molecules and nano-SiO₂ particles.DSC data showed that nano-SiO₂ particles into polyacrylate resin enhanced glass temperature.The resins separated from the composite were investigated by High performance gel permeation chromatography(HPGPC).Baking varnishes were prepared with polyacrylate/nano-SiO₂ composite resin and amino resin.Sagging resistant of the baking varnish,the hardness and abrasion resistant of the film were improved and leveling properties,gloss,adhesion and flexibility get worse with the increase of the content of nano-SiO₂.The appropriate amount of nano-SiO₂ can improve the impact strength and solvent resistance.Baking varnish obtained from In situ polymerization improved sagging resistant,the hardness and abrasion resistant more intensively.Then two-component polyurethane coatings were prepared with polyacrylate/nano-SiO₂ composite resin and polyisocyanates resin.The mechanical properties and gloss of this coating were investigated.The results showed the hardness and abrasion resistant of the film were improved and leveling properties, gloss and flexibility get worse with the increase of the content of nano-SiO₂.The appropriate amount of nano-SiO₂ can improve adhesion and solvent resistance.The method of In situ polymerization improved sagging resistant,the hardness and abrasion resistant more intensively than the method of blend.