Study On Synthesis And Application Of Surface Modifier For Active Nano-CaCO₃

Nano-calcium carbonate is widely used as an important inorganic filler in many industrial fields, such as plastic, rubber and coatings etc. However, the interface interaction between CaCO3and organic matrix is-weakened due to its hydrophilicity. So the mechanical properties of composite materials are decreased. Besides, normal nano-CaCO3is easily aggregated because of its small particle size and high surface energy.The problems can be solved by surface modification of nano-CaCO3. Modified nano-CaCO3becomes hydrophobicity and low surface energy, So its dispersion in the organic matrix is improved. In China, active nano-CaCO3prepared has shortcomings, such as bad dispersion, poor compatibility with the polymers and high specific gravity etc. The research purpose of this paper is to improve the surface modification of nano-CaCO3.In this paper, modified glycerin ester was taken place of pure fatty acid ester which was widely used nowadays to be nano-CaCO3modifier. Glycery1di-caprylate/caprate was synthesized by ester exchange method, and then reacted with ethylene oxide to prepare glyceryl di-caprylate/caprate polyoxyethylene ether.Firstly, the optimal reaction conditions, of synthetizing glyceryl di-caprylate/caprate were obtained as follow:0.3%catalyst sodium methylate, reaction temperature at110～120℃, vaccum degree at0.02to0MPa. Secondly, the optimal reaction conditions of synthetizing glyceryl di-caprylate/caprate polyoxyethylene other were confirmed:0.4%catalyst KOH. reaction temperature at110～120℃. stirring speed at500r/min.Besides, new technique of preparing active nano-CaCO3was put forward. Active nano-CaCO3was prepared at normal temperature through this process.And the optimal modification conditions were attained:20%concentration of Ca(OH)2.1.5%composite modifiers which consisted of glyceryl di-caprylate/caprate polyoxyethylene ether and oleic acid with ratio of1:1, and stirring speed at300r/min. Activation index, oil absorption value and average particle size of active nano-CaCO3prepared were measured, and its physical properties were confirmed by means of TGA, IR and TEM etc. The results of research indicated that the properties of active nano-CaCO3prepared through this technique had been similar to foreign products:activation index was100%. oil absorption value was31.5, the average particle size was51nm, and the surface modifier had formed strong chemical bonds with nano-CaCO3Compared with common modification technique, this technique is environmental friendly and has low energy consumption and simple process.