Preparation of micron-sized polymerized toner by suspension polymerization for electrophotographic printers

Abstract

Polymerized toners by suspension polymerization for electrophotographic printers were performed in an aqueous medium in the presence of poly (vinyl alcohol) and benzoyl peroxide as a dispersant, and an initiator, respectively. The effects of reaction parameters were the mechanical homogenizing speed, agitation rate, initiator concentration, reaction temperature, monomer feed ratio, dispersant concentration, reaction time, crosslinking agent concentration, carbon black feed level, and charge control agent concentration on the particle size, size distribution, molecular weight, molecular weight distribution, thermal properties, triboelectric properties and other important properties necessary to polymerized toner were investigated. The particle size and size distribution were measured by SEM; the average molecular weight by GPC, the functional groups by FTIR; alas transition temperature (Tg) by DSC; and triboelectric property by blow-off method. The resulting polymerized toners were found to be smooth on their spherical surface and the particle sizes were in the range of 4-10 µm with a CV of 20-30%. In most cases, the correlation between small particle sizes with high average molecular weights was observed. Tg of the polymerized toner could be controlled by the mole ratio of the comonomer between styrene and nBA. Tg values decreased when the content of nBA in copolymer increase due to its rubbery state along with the increasing of carbon black feed level, the surface functional groups of carbon black pigment inhibited the rate of polymerization and decreased the molecular weight of the resulting polymerized toners. Tg values of the resulting polymerized toners were in the range of 66-70℃. Triboelectricity (q/m) of the resulting polymerized toners were 7-20 µC g-1. Analysis of print quality with respect to the q/m values showed the higher background fog, low maximum density, and a small image raggedness. This thesis elucidated the polymerizing efficiency, charging properties, and image qualities.