Synthesis And Performance Of High Solid-content Polyacrylate Microemulsion

Polyacrylate emulsion has wide applications in printing ink, paints, adhesives, and polishing material, but traditional polyacrylic emulsion is difficult to satisfy urgent demands such as high-grade wood coatings, high quality and high functionalization. So the traditional polyacrylate emulsion of super small particle, namely synthetic polyacrylate microemulsion, should be super-fine particalized,increasing sharply its function, and even obtaining some specific functions, Thus it meets the needs of high quality and high functionalization. At present microemulsion is commonly obtained by employing the method of synthetic polyacrylate microemulsion and the method of polyacrylate microemulsion obtained by the conventional emulsion polymerization is less reported. The latex particle size of the Polyacrylate emulsion prepared by the conditional method is too large (200～500nm), the transparency of the latex film, and film forming performance are poor, although the content of emulsifier is low. Therefore it cannot satisfy the requirements of high quality and high functionalization. However, the current polyacrylate microemulsion synthesis by microemulsion polymerization has also some defects such as low concentration, poor water resistance,and low fullness because of a large amount of emulsifier and a low amount of monomer used in the synthetic process and therefore limits its applications in industry. In this paper,inspired by the thought of "particle design", we choose conventional emulsion polymerization and the improved and modified microemulsion polymerization to synthesis low emulsifier content, and high solid content polyacrylate microemulsion.The contents and the related results in the research are as follows:(1) The high solid content polyacrylate microemulsion is successfully synthesized by the improvement of conventional emulsion polymerization with emulsifier content1.5%(based on the total latex), monomer50%(based on the total latex), average particle size39nm, polydispersity of particle size0.139. The influences parameters of polymerization technology such as the type and level of emulsifier, the concentration and addition sequence of initiator, the amount of functional monomer, the polymerization temperature, the amount of electrolyte, and the rate of agitation, on particle size and performance of polyacrylate microemulsion are studied. The polyacrylate microemulsion and its film are characterized by Transmission electron microscopy (TEM),Fourier Transform Infrared Spectroscopy (FTIR), Thermo-Gravimetric Analysis(TG) and Gel Permealtion Chromatography(GPC). The results show that the polyacrylate microemulsion with small particle size, narrow distribution and performance will be successfully synthesized if MMA/BA/AA68/28/4, monomer50%, emulsifier content1.5%, Emulsogen APS/OP-102/1, initiator(APS)0.15%, electrolyte(NaHCO3)0.1%, and pre-emulsion temperature20～30℃.(2) The high solid content polyacrylate microemulsion is successfully synthesized by the improvement of microemulsion polymerization with emulsifier content2%(based on the total latex), monomer40%(based on the total latex), average particle size36.5nm, polydispersity of particle size0.158. The effects of polymerization technology including the type and level of emulsifier, the concentration and addition sequence of initiator, monomer emulsion, the amount of electrolyte, and polymerization temperature on the particle size and performance of microemulsion are investigated. The experimental results show that the synthesis of high solid content polyacrylate microemulsion can be successful if the following factors, MMA/BA/AA68/32/4, monomer40%, emulsifier content2%, Emulsogen APS/OP-102/1, initiator(APS)0.15%, electrolyte(NaHCO3)0.2%, and pre-emulsion temperature45～50℃are satisfied.(3) The experiment results show that polyacrylate microemulsion with high solid content and small emulsifier content can be successfully synthesized by the improvement of conventional emulsion polymerization and improvement of microemulsion polymerization of the optimum polymerization process. Compared with the improvement of conventional emulsion polymerization, technological requirements of the improvement of microemulsion polymerization are more rigorous, and the performance of the synthestic polyacrylate microemulsion gets poorer than that of the improvement of conventional emulsion polymerization.