Investigation On Composition And Properties Of Microencapsulated Electrophoretic Display Ink

The paper-like display that named electronic-paper is studied intensively in recent years. For the properties of digital driving, bistable information storing, portability and flexibility, Lambert' s reflection and wide visual angle, electronic paper will be widely used in the fields of display, decoration, electronic book, electronic newspapers and so on. So the market potential of electronic paper is great.Encapsulated electrophoretic ink is studied in this paper. Based on the preparation of electrophoretic liquid, the study is focused on the relationship between composition and properties of the electrophoretic ink.Most of the reported prototype electronic papers are based on the electronic ink colloidal suspension, which take the inorganic pigment titanox or silica as electrophoresis particle. The property of inorganic particle system is studied perfectly. There are less reports about organic pigment particle electrophoresis colloid. This paper focused on the system of organic pigment electrophoretic liquids is illustrated as follows:The colloidal suspension is the active and most crucial part of the eletrophoresis electronic paper. The adsorption of dyes on the surface of pigment was tested qualitative by thin-layer chromatography (TLC) for a series of dyes. The coloration of dyes on microcapsule film was tested too. Combined with the spectrum of dyes and pigments, the dyes of solvent Sudan Red series are selected. The spectrum and the zeta potential of different brand diarylide yellow pigment in mixed xylene and tetrachloroethylene were compared. The testing result shows that the C. I. PY14 which density matched to, and dispersed in, a solvent medium of tetrachloroethylene and xylene is the best one. The reaction between many charge control agents (CCA) and C. I. PY14 proved that the mechanism of PY14 charging is based on Lewis acidic-basic reaction. And the basic property of substituted amines was found by the zeta potential:(1) in the nopolar media colloidal system, primary is weak than secondary, and the third ethylamine is the strongest. (2) as to the longer chain substituted amines, the steric always lead to weaker basic. An imide-type copolymer namely polyisobutylene imide (PIBI) is a good CCA and stabilizer of C. I. PY14. The copolymer consists of a 100-200nm long hydrocarbon chain acts as a stericIpart of the stabilization and an amine group which assists in the charging and adsorption mechanism of the pigment surface.All the components such as solvent, CCA, pigment and dye were balled to produce electrophoretic ink in different ratio. The affecting of water to nopolar media electrophoretic ink was studied. It is found both water-based acid and base lead to the stability and zeta potential change of electrophoretic ink. The electrophoresis properties such as response speed, optic density and displaying density field were studied. The influence of CCA, dispersion of pigment and thicker of test cell to the display were also studied. Based on the above study, the electrophoretic liquid was optimized. It is found that ET-14 is a good stability of the electrophoretic ink and many electrophoresis properties were improved.The encapsulating of electrophoretic ink is one of the key technologies of electronic paper. Three microencapsulation techniques are used in this paper: the coacervation approach, the in situ polymerization and suspension polymerization. Many experiments were carried out to choose the better curing agent and better process. Conclusions were made that the microcapsule produced by coacervation features high transparency, good flexiblity, and the prepolymer of urea and formaldehyde is a good curing agent of gelatin and acacia. The binder was selected according to the property of microcapsule. High contrast displaying film of microencapsulated electrophoretic ink was achieved, and the electrophoresis property of the film was tested. It was found that the property of microcapsulated electrophoretic ink display is similar to the non-encapsulated electrophoretic display.The great p...