Preparation of Polyester Toner Particles with a Self-Emulsified Chemical Milling Method

Abstract

Various dispersion polymerization methods have emerged as an economical means of producing small sized toner particles thus to enhance the resolution of electrophotography (EP) images to a higher level. The socalled polymerized toners generally have a small average particle size, a narrow size distribution and a round particle shape with a smooth surface. However, the polymerization methods present several difficulties such as complexity of process and production facility, potential for solvent or monomer contamination of the toner particles, inflexibility of formulation variation and slow charging characteristics. Recently we developed and reported the novel chemical milling (CM) method of producing small polyester toner particles, which has the advantages of the polymerization methods but, at the same time, are free of the abovementioned disadvantages.Here we present a self-emulsified CM method, a modification of the chemical milling method as well as the physical properties and EP performance of toners prepared by the method. The method takes advantages of the physical and surface chemical properties of novel polyester toner resins and thus does not require use of a process aid or a surfactant in the toner particle formation. Much like the traditional CM method, the method exhibits excellent controllability and economy in the production of spherical polyester toner particles with a small diameter and a narrow size distribution. We demonstrate toner particles with the volumetric mean diameter of about 6 μm and the 80% span of 0.6.