The Preparation Of Nano-silica/styrene Acrylic Composite Latex

Because of the excellent performance,such as resistance,adhesion,transparency,and low cost,the latice of poly styrene-acrylic have been widely used in waterborne coatings.However,due to its much lower hardness,the application in wood coatings has been greatly limited.How to improve the hardness has been the key to make it used in wooden furniture coating or anti-corrosion coating.In this paper,the styrene-acrylic latex modified by nano SiO2 was prepared by emulsion polymerization with St,MMA,BA,AA,unsaturated siloxane as monomer which was synthesized in our laboratory,and the performance of the latex film was improved.The main research works and the related results were as follows:Firstly,a kind of process was designed to synthesize unsaturated siloxane monomer.The tetramethoxysilan(TMOS),cyclohexanoland,2-hydroxyethyl methacrylate(HEMA)were used as main materials and sulfuric acid was used as catalyst.The inhibitor is 4-methoxyphenol,the azeotrope of methanol is n-hexane,the reaction temperature is 75℃.Secondly,a series of unsaturated siloxane monomer were prepared respectly and the effect of water content on the ester exchange reaction was researched.The results shown that water content have small effect on the reaction time and flocculating rate increased with the increase of water content.The chemical structure and content of the ester product was analyzed by GC-MS.Finally,nano-silica/styrene-acrylic composite latex were prepared by emulsion polymerization with unsaturated siloxane monomer,St,MMA,BA,AA,CO-436 as emulsifier,potassium persulfate as initiator,NaHC03 as pH buffer.The effect of unsaturated siloxane monomer dosage on stability of emulsion polymerization,particle size,viscosity of latex,hardness of latex film,the adhesion of latex film,Water absorption of latex film was researched,and the latex film was studied by TEM,IR,XRD.The experiments shown that nano-silica was found in the latex film,the hardness of the latex film reached H.