Preparation of Toner Particles with Micro-serrated Texture by Chemical Milling

Abstract

Recently various dispersion polymerization methods have emerged as an economical alternative for producing small sized toners and thus improving the resolution of electrophotography (EP) images. The polymerized toners generally have a small particle size, a narrow size distribution and a spherical shape with a smooth surface. However, the methods present several difficulties such as process and equipment complexity, potential for solvent contamination of toner particles, inflexibility of formulation variation and slow charging characteristics.We developed a novel chemical milling method of producing small toner particles, which has the advantages of the polymerization methods but are free of the abovementioned disadvantages. The spherical toner particles produced by the chemical milling method may have the mean diameter any value in the range of 3-15 μm with a simple adjustment of the process parameters. The particles generally have a narrow size distribution with the span (= (d90-d10)/d50) as low as 0.6. Furthermore, the particle surface morphology may be controlled to have a rough texture, which significantly improves the charging characteristics of the particles. The process is applicable for a wide range of binder resins, including commercial styrene/acrylic and polyester resins. Physical properties of the chemically milled toners as well as their EP performance are presented.