Adhesive and sealing layers for electrophoretic displays

Abstract

The invention is directed to compositions and methods for improving the physicomechanical and electro-optical properties of an electrophoretic or liquid crystal display and also to semi-finished or finished display panels with improved physicomechanical properties. The invention is further directed to a display device comprising display cells filled with a display fluid and top-sealed with a top-sealing layer, wherein the top-sealing layer has a thickness of less than 10 microns measured at the center area.

What is claimed is: 
     
         1 . A semi-finished display panel comprising an array of display cells disposed between two temporary substrate layers, the display cells being filled with a display fluid comprising a dielectric solvent, and being top-sealed with a top-sealing layer,
 wherein the top-sealing layer is formed from a sealing composition comprising a functionalized polyurethane and a radiation curable composition,   wherein the top-sealing layer has a thickness of between about 1 micron and 8 microns,   wherein the functionalized polyurethane has a dielectric constant higher than that of the dielectric solvent, and   wherein the functionalized polyurethane comprises a functional group selected from a group consisting of —OH, —SH, —NCO, —NCS, —NHR, —NRCONHR, —NRCSNHR, and epoxide, wherein R is hydrogen, alkyl, aryl, alkylaryl or arylalkyl of up to 20 carbon atoms.   
     
     
         2 . The semi-finished display panel of  claim 1 , wherein the radiation curable composition comprises a multifunctional monomer or oligomer. 
     
     
         3 . The semi-finished display panel of  claim 1 , wherein the sealing composition further comprises a crosslinking agent. 
     
     
         4 . The semi-finished display panel of  claim 3 , wherein the sealing composition further comprises a catalyst. 
     
     
         5 . The semi-finished display panel of  claim 1 , wherein the functionalized polyurethane comprises a hydroxyl terminated polyester polyurethane, a hydroxyl terminated polyether polyurethane, an isocyanate terminated polyester polyurethane, an isocyanate terminated polyether polyurethane, an acrylate terminated polyester polyurethane, or an acrylate terminated polyether polyurethane. 
     
     
         6 . The semi-finished display panel of  claim 1 , wherein the sealing composition has a specific gravity not greater than that of the display fluid. 
     
     
         7 . The semi-finished display panel of  claim 1 , wherein the display cells are microcups. 
     
     
         8 . The semi-finished display panel of  claim 7 , wherein the microcups are prepared by embossing or lithography. 
     
     
         9 . The semi-finished display panel of  claim 1 , wherein the temporary substrate is a release liner. 
     
     
         10 . The semi-finished display panel of  claim 9 , wherein the panel is in the form of a roll. 
     
     
         11 . The semi-finished display panel of  claim 1 , wherein the top-sealing layer has a thickness of between about 3 microns and 6 microns. 
     
     
         12 . The semi-finished display panel of  claim 1 , wherein the panel is in the form of a roll.