Electro-optic displays, and materials for use therein

Abstract

A first electro-optic display comprises first and second substrates, and an adhesive layer and a layer of electro-optic material disposed between the first and second substrates, the adhesive layer comprising a mixture of a polymeric adhesive material and a hydroxyl containing polymer having a number average molecular weight not greater than about 5000. A second electro-optic display is similar to the first but has an adhesive layer comprising a thermally-activated cross-linking agent to reduce void growth when the display is subjected to temperature changes. A third electro-optic display, intended for writing with a stylus or similar instrument, is produced by forming a layer of an electro-optic material on an electrode; depositing a substantially solvent-free polymerizable liquid material over the electro-optic material; and polymerizing the polymerizable liquid material.

1 . An electro-optic display capable of being imaged by a stylus, the display comprising:
 an electrode;   a layer of an electro-optic material disposed on the electrode, such that the surface of the layer of electro-optic material remote from the electrode is non-planar; and   a polymeric layer overlying the layer of electro-optic material,   the polymeric layer comprising the polymerization product of a substantially solvent-free polymerizable liquid material, the surface of the polymeric layer remote from the layer of electro-optic material being substantially planar and forming an exposed external surface of the display on which a stylus can be placed.   
     
     
         2 . An electro-optic display according to  claim 1  wherein the thickness of the polymeric layer is from about 6 to about 250 μm. 
     
     
         3 . An electro-optic display according to  claim 2  wherein the thickness of the polymeric layer is from about 8 to about 50 μm. 
     
     
         4 . An electro-optic display according to  claim 1  wherein the polymeric layer comprises an acrylate or a urethane acrylate blend or a silicone. 
     
     
         5 . An electro-optic display according to  claim 1  wherein the electro-optic material comprises a rotating bichromal member or electrochromic material. 
     
     
         6 . An electro-optic display according to  claim 1  wherein the electro-optic material comprises an electrophoretic material comprising a plurality of electrically charged particles disposed in a fluid and capable of moving through the fluid under the influence of an electric field. 
     
     
         7 . An electro-optic display according to  claim 6  wherein the electrically charged particles and the fluid are present as a plurality of discrete droplets surrounded by a continuous phase comprising a polymeric material. 
     
     
         8 . An electro-optic display according to  claim 6  wherein the fluid is gaseous. 
     
     
         9 . A process for the preparation of an electro-optic display, the process comprising:
 forming a layer of an electro-optic material on an electrode, the surface of the layer of electro-optic material remote from the electrode being non-planar;   depositing a layer of a substantially solvent-free polymerizable liquid material over the layer of electro-optic material; and   exposing the polymerizable liquid material to conditions effective to cause polymerization of the material, thereby forming a polymeric layer overlying the layer of electro-optic material, the surface of the polymeric layer remote from the layer of electro-optic material being substantially planar and forming an exposed external surface of the display.   
     
     
         10 . A process according to  claim 9  wherein the thickness of the polymeric layer is from about 6 to about 250 μm. 
     
     
         11 . A process according to  claim 9  wherein the thickness of the polymeric layer is from about 8 to about 50 μm. 
     
     
         12 . A process according to  claim 9  wherein the polymeric layer comprises an acrylate or a urethane acrylate blend or a silicone. 
     
     
         13 . A process according to  claim 9  wherein the electro-optic material comprises a rotating bichromal member or electrochromic material. 
     
     
         14 . A process according to  claim 9  wherein the electro-optic material comprises an electrophoretic material comprising a plurality of electrically charged particles disposed in a fluid and capable of moving through the fluid under the influence of an electric field. 
     
     
         15 . A process according to  claim 14  wherein the electrically charged particles and the fluid are present as a plurality of discrete droplets surrounded by a continuous phase comprising a polymeric material. 
     
     
         16 . A process according to  claim 14  wherein the fluid is gaseous.