|
Polyacrylate emulsion not only with environmental pollution, mild reaction conditions, and the wide range of sources of raw materials and latex film, good weather resistance, high transparency, flexibility, etc.. Polyacrylate emulsion also has some disadvantages, if latex film poor in heat resistance, low hardness is difficult to meet the high performance requirements of the field. Nano-silica as a reinforcing material, polyacrylate emulsion can improve the performance of the coating abrasion resistance, scratch resistance, UV resistance. The two composite-forming the composite material of both organic and inorganic characteristics to become the focus of current research. In this thesis, in situ emulsion polymerization method, the reaction of a homemade modified nano-silica particles with methyl methacrylate (MMA), butyl acrylate (BA) and acrylic acid (AA) monomer, to prepare a nano dioxide silicon / polyacrylate hybrid emulsion, and the study of its structure and performance. The main contents and results of this paper include the following aspects: First, the use of the methacryloyloxy trimethoxysilane (KH-570) modified the sol and emulsifier instead of alcohols as stable agent KH-570 modified silica sol prepared. The effects of pH, emulsifier type and dosage, KH-570 used sol modified. The results showed that: when the pH value of 5 to 7, using sodium dodecyl sulfate (SDS) as a stabilizer, with the mass ratio of the KH-570 is 0.25, KH-570 used in an amount of 10% to 20% can be prepared was stable KH-570 modified silica sol. Second, modified silica sol and MMA, BA and AA by in situ emulsion polymerization sol modified polyacrylate hybrid emulsion. KH-570, emulsifier and nano of silica amount of emulsion polymerization and latex film. The results showed that: When the emulsifier DNS-86, KH-570 and nano-silica were used in an amount of 3%, 10% to 20% and 5% to 8%, can be prepared by high stability and low gel fraction of silicon sol modified polyacrylate composite latex, and latex film with good mechanical and thermal properties. Acrylate monomer in the oil phase medium positive ethyl silicate (TEOS) as precursors, KH-570 as a modifier, modified nano-dispersed micelles were prepared by the emulsion method The silicon oxide pre-emulsion. Emulsifier type and dosage, pH value, the ratio of oil to water, TEOS amount of the pre-emulsion stability. The results show that: when emulsifier DNS-86 accounts for the pre-emulsion monomer quality scores of 6%, a pH value of 2, the mass ratio of the oil phase substances with water 1:1, the TEOS accounted monomer mass fraction of 50% or less obtained good stability of the modified nano silica pre-emulsion. Fourth, the modified nano-silica the preemulsion acrylate monomer by in situ emulsion polymerization combined with core-shell polymerization prepared nano silica / polyacrylate hybrid emulsion. Polymerization temperature, the amount of emulsifier and coupling agent and silica content of the emulsion polymerization and latex film, and the means of transmission electron microscopy (TEM), FTIR, TG, DSL, structure and properties of composite emulsion characterization. The results show that: the DNS-86 used in such an amount as when the polymerization temperature at 75 to 80 ° C, the emulsifying agent was 5%, KH-570 with TEOS molar ratio of 0.075, the silica content of 4%, can be prepared by gel-free, high stability The nature of the emulsion, and the latex film with excellent mechanical resistance, the dielectric and thermal properties. TEM analysis showed that the structure of the nano-silica composite latex particles coated with polyacrylate.
|