ELECTROPHORETIC FLUID

Abstract

This invention relates to electrophoretic fluids comprising at least two immiscible liquids and black, white and/or coloured particles and/or dyes, and electrophoretic display devices comprising such fluids.

Claims

1.-8. (canceled)

9. An electrophoretic fluid comprising at least two immiscible liquids and black, white and/or colored particles and/or dyes dispersed or dissolved in at least one of the liquids.

10. The electrophoretic fluid according to claim 9, wherein the immiscible liquids are selected from hydrocarbon solvents and fluorinated solvents.

11. The electrophoretic fluid according to claim 9, wherein hydrocarbon solvents are selected from the group consisting of naphtha, decalin, tetralin, dodecane, tetradecane, decane and nonane.

12. The electrophoretic fluid according to claim 9, wherein fluorinated solvents are nonpolar and are selected from perfluorinated solvents and partially fluorinated solvents.

13. The electrophoretic fluid according to claim 9, wherein black, white and/or coloured particles and/or dyes are absorbing particles or dyes and are dispersed or dissolved in the hydrocarbon solvent.

14. The electrophoretic fluid according to claim 9, wherein the black, white and/or coloured particles are reflective particles and are dispersed in the fluorinated solvents.

15. An electrophoretic display device comprising an electrophoretic fluid according to claim 9.

16. The electrophoretic display device according to claim 15, wherein the electrophoretic fluid is applied by a technique selected from inkjet printing, slot die spraying, nozzle spraying, and flexographic printing, or any other contact or contactless printing or deposition technique.

Description

EXAMPLES

[0037] Dual-phase formulations are synthesised and analysed using a Nikon LV100 Eclipse microscope at 5× magnification. A test cell setup consisting of 500 micron spaced interdigitated finger electrodes is used, with a spacer of 15 microns applied to the cell, and a plain glass slide placed on top of the substrate to ensure even filling of the cell. The cell is imaged with 0V applied. A DC 180V (field=0.36V/micron) voltage is applied between the electrodes, and the movement of particles/solvent is observed and imaged. Further, a DC 250V (field=0.50V/micron) voltage is applied between the electrodes, and the movement of particles/solvent is observed and imaged.

Example 1: Dual Phase Solvent Mixture—Charge Independent

[0038] 0.95 g of Dodecane is mixed with 0.38 g of Novec® 7500 and filled into a test cell. Images are taken at 0V, 180V and 250V. At zero voltage the Novec 7500 has no alignment with the electrodes. When 180V is applied, the Novec® 7500 shows an attraction to the electrodes. At 250V the electrodes are completely covered by the Novec® 7500, regardless of polarity (both −ve and +ve electrodes are covered with Novec® 7500).

Example 2: Dual Phase Solvent Mixture+Particles—Charge Controlled

[0039] 0.105 g of black polymer particles are dispersed in 1.245 g of dodecane along with 0.02 g of Infineum E and added to 0.709 g of Novec® 7500. The resultant mixture is filled into a test cell. Images are taken at +250V and −250V. The solvent can be controllably displaced and aligned with the desired electrode. The particles also show electrophoretic movement and are attracted to the opposite electrode.

Example 3: Dual Phase Solvent Mixture+Dual Particle Sets—Charge Controlled

[0040] In this example, white TiO.sub.2 particles are dispersed in the fluorinated phase with Krytox®, and black dyed PMMA particles are dispersed in the hydrocarbon phase with Infineum E. The particles cannot be mixed as they are in different solvent phases. This leads to very defined separation of the black and white particles.