Studies On The Preparation And Aggregation Of Nano-composite Latex Particles

In order to prepare color toners with excellent performance,styrene-butyl acrylate copolymer resin co-encapsulated organic pigment red 48:2(PR48:2)and oxidized polyethylene(OPE)wax nano-composite latex particles were prepared by in-situ emulsion polymerization in this paper.The effect of the dispersion method and amount of emulsifier and pigment on the properties of nano-composite particles was studied.On the basis of the successful preparation of nano latex particle emulsion,micron-sized composite particles were achieved by two different aggregation methods of inorganic salt aggregation and charge neutralization agglomeration of different electrical latex particles,which realized the controllable adjustment of size and morphology of aggregated particles.The morphology,particle size and size distribution,thermal property,color performance and structure of nano latex particles were characterized by transmission electron microscopy,nanoparticle size analyzer,thermogravimetric analyzer,differential scanning calorimeter,colorimeter and Fourier infrared spectrometer.The particle size,Zeta potential and morphology of the aggregated microparticles were analyzed by ultra-high speed intelligent particle size analyzer,Zeta potential meter and scanning electron microscope.The research conclusions were as follows:In the process of preparing nano-composite latex particles of styrene-butyl acrylate resin co-encapsulated PR48:2 and OPE wax by in situ emulsion polymerization,ball milling dispersion technique was a more effective method to prepare particles with uniform dispersion,small size and narrow size distribution.When the emulsifier concentration was0.01mol/L,the prepared emulsion had good storage stability,and the obtained composite latex particles had uniform dispersion,good encapsulation property,narrow particle size distribution and clear core-shell structure.The UV aging resistance of organic pigments was obviously enhanced after being encapsulated with resin,and as the pigment content increased,the UV aging resistance decreased.With the increase of pigment content,the lightness value(L*)of the composite particles decreased and red value(a*)increased.When the pigment content was 0.5g,the color saturation(c*)of the composite particles was the largest,and the color performance was better.In the process of the inorganic salt aggregation,the evolution of the nano latex particles aggregation was studied,and the controllable regulation of the particle size and morphology of the aggregated particles could be realized by changing the inorganic salt concentration,stirring speed and system temperature.The emulsion of styrene-butyl acrylate resin encapsulated pigment yellow 17(PY17)was synthesized firstly by miniemulsion polymerization.Under the condition that the amount of emulsifier was 5wt%of the comonomer,the prepared nano latex particles had good dispersibility and clear core shell structure,and the emulsion had good stability,which was favorable for subsequent aggregation of nano latex particles.During the process of inorganic salt aggregation,the size of the aggregated particles increased at first and then decreased,and the Zeta potential of the system had a tendency of decrease.The average size of the aggragated particles gradually increased with the increase of the the Al Cl₃ solution concentration and decreased with the increase of the stirring speed.In a certain temperature range,higher curing and reshaping temperatures were beneficial to the formation of regular morphology of aggregated particles.When the Al Cl₃ solution concentration,the stirring speed,the curing temperature and the reshaping temperature were 0.2mol/L,1000rpm,65?and 72?,respectively,the prepared aggregated particles had the advantages of suitable particle size,narrow particle size distribution and regular shape.In the charge neutralization agglomeration experiment of different electrical latex particles,electropositive and electronegative emulsions were prepared respectively.When the CTAB content was 0.1g,the Zeta potential of the prepared electropositive emulsion was40.6m V;when the dilution factor of the electronegative emulsion was 8 times,the Zeta potential of electronegative emulsion was-40.2m V.During the aggregation process,the condensed particle size increased at first and then decreased,and the Zeta potential of the system decreased rapidly and then increased slowly.With the increase of stirring speed,the average size of condensed particles decreased gradually,and the width of size distribution decreased at first and then increased.At the same time,the stirring speed also had a significant effect on the morphology of condensed particles.When the stirring rate was900rpm,the condensed particles had suitable size and narrow size distribution,and some condensed particles had regular shape.With the increase of system temperature,the morphology of condensed particles tended to be regular.When the reshaping temperature reached 70?,a large number of particles showed regular sphere shape,and there were almost no cracks and pores on the surface of condensed particles.