Synthesis And Performance Of Silicone-acrylic Emulsion

Water-based coatings were composed of the polymer emulsion, pigment and a variety ofadditives, and the polymer emulsion determines the performance of the coating. The polymeremulsion was mainly composed of polymer latex particles (here in after referred to latexparticles) and water, therefore the preparation of high-performance water-based polymeremulsion is the key of achieving water-based coatings. Core-shell silicone-acrylic Emulsionwas synthesized by in the shell polymerization stage of synthesizing core-shell acrylate latex,which improved the compatibility between polysiloxane and polyacrylate and the defect ofembedded of silicon unit.In this paper, semi-continuous seed emulsion polymerization associated withpre-emulsification process was used for preparing acrylate emulsion. Polysiloxane modifiedcore-shell acrylate latex was synthesized with methyl methacrylate (MMA) and butylacrylate(BA) as monomers, methyl acrylicacid (AA) and organosilicon as functional monomer,ammonium persulfate (APS) as initiator. The influences of Emulsifiers’ type, the content ofthe emulsifier, the proportion of anion/non-ionic compound emulsifiers, the content ofinitiator, the ratio of soft/hard monomer, the adding method of organosilicon and the contentof organosilicon and so on had been investigated in this paper. The basic processingparameters and production formula were determined. The composition and properties such asparticle morphology, particle size and its distribution of the obtained silicone-acrylate latexwere characterized. The effect of organosilicon monomer content on the performances ofresulting latex film was investigated by its transparence, water absorption, contact angles ofwater and IR.The results show that the reaction temperature is80℃, the mechanical rabble speed is250~350rmp, the reaction time is5h. the best type of emulsifier is A/B/OP, the content ofemulsifier, initiator, MAA and organosilicon was respectively2.5%,0.5%,5%and3%.Thelatex film has excellent performance when the proportion of anion/non-ionic compoundemulsions was1:1, the ratio on the core/shell stage is2:1, MAA and organosilicon were added in shell phase. The latex films were improved with organosilicon on Pencil hardness, Scratchresistance and water resistance.