Microcup compositions having improved flexure resistance and release properties

Abstract

This invention relates to a novel composition suitable for use in the manufacture of electrophoretic display cells. The mechanical properties of the cells are significantly improved with this composition in which a rubber material is incorporated.

What is claimed is:  
     
         1 . An electrophoretic display comprising cells formed from a composition comprising a radiation curable material and a rubber material.  
     
     
         2 . The electrophoretic display of  claim 1  wherein the radiation curable material is a thermoplastic or thermoset precursor.  
     
     
         3 . The electrophoretic display of  claim 2  wherein said thermoplastic or thermoset precursor is multifunctional acrylate or methacrylate, vinylether, epoxide and their oligomers, polymers and the like.  
     
     
         4 . The electrophoretic display of  claim 3  wherein said thermoplastic or theormoset precursor is a multifunctional acrylate and its oligomers.  
     
     
         5 . The electrophoretic display of  claim 2  wherein said radiation curable material is a combination of multifunctional epoxide and multifunctional acrylate.  
     
     
         6 . The electrophoretic display of  claim 1  wherein the rubber material has a glass transition temperature lower than about 0° C.  
     
     
         7 . The electrophoretic display of  claim 6  wherein the rubber material is unsaturated.  
     
     
         8 . The electrophoretic display of  claim 7  wherein the rubber material has uncapped or side chain unsaturated groups such as vinyl, acrylate, methacrylate or allyl groups.  
     
     
         9 . The electrophoretic display of  claim 1  wherein said rubber material is selected from a group consisting of SBR (styrene-butadiene rubber), PBR (polybutadiene rubber), NBR (acrylonitrile-butadiene rubber), SBS (styrene-butadiene-styrene block copolymer), SIS (styrene-isoprene-styrene block copolymer), and their derivatives.  
     
     
         10 . The electrophoretic display of  claim 9  wherein said rubber material is polybutadiene dimethacrylate, graft (meth)acrylated hydrocarbon polymer or methacrylate terminated butadiene-acrylonitrile copolymers.  
     
     
         11 . The electrophoretic display of  claim 1  wherein said composition comprising from about 1 to about 30% by weight of the rubber material.  
     
     
         12 . The electrophoretic display of  claim 11  wherein said composition comprising from about 5 to about 20% by weight of the rubber material.  
     
     
         13 . The electrophoretic display of  claim 12  wherein said composition comprising from about 8 to about 15% by weight of the rubber material.  
     
     
         14 . A process for the manufacture of an electrophoretic display which process comprises forming microcups by microembossing using a composition comprising a radiation curable material and a rubber material.  
     
     
         15 . A process for the manufacture of an electrophoretic display which process comprises forming microcups by photolithography using a composition comprising a radiation curable material and a rubber material.