Electro-optic assemblies, and adhesives and binders for use therein

Abstract

An electro-optic assembly comprises an adhesive layer and a layer of electro-optic material. The adhesive layer comprises a polymeric adhesive material and an ionic material having either its cation or its anion fixed to the polymeric adhesive material. The ionic material reduces the volume resistivity of the polymeric adhesive material and is not removed upon heating to 50° C. In a similar electro-optic assembly comprising an adhesive layer and a layer of electro-optic material, the adhesive layer comprises a polymeric adhesive material which has been subjected to dialysis or diafiltration to remove organic species having a molecular weight less than about 3,500, so that the adhesive material has a content of N-methylpyrrolidone not exceeding 500 ppm based upon the total weight of the adhesive layer and layer of electro-optic material.

1 . An electro-optic assembly comprising an adhesive layer and a layer of electro-optic material, the adhesive layer comprising a polymeric adhesive material and an ionic material, the ionic material having one of its cation and anion fixed to the polymeric adhesive material and the other of its cation and anion free to migrate through the polymeric adhesive material, the ionic material reducing the volume resistivity of the polymeric adhesive material and not being removed by heating the polymeric adhesive material to about 50° C. 
   
   
       2 . An electro-optic assembly according to  claim 1  wherein the ionic material comprises a quaternary ammonium or phosphonium cation and a carboxylate anion fixed to the polymeric adhesive material. 
   
   
       3 . An electro-optic assembly according to  claim 1  wherein the polymeric adhesive material comprises a polyurethane. 
   
   
       4 . An electro-optic assembly according to  claim 1  wherein the ionic material comprises a quaternary ammonium or phosphonium cation fixed to the polymeric adhesive material and a hexafluorophosphate, tetrabutylborate or tetraphenylborate anion. 
   
   
       5 . An electro-optic assembly according to  claim 1  wherein the ionic material comprises repeating units derived from a basic monomer and a mobile anion selected from the group comprising sulfonates, sulfates, hexafluorophosphates, tetrafluoroborates, bis(methanesulfonyl)imidate, phosphates and phosphonates. 
   
   
       6 . An electro-optic assembly according to  claim 5  wherein the basic monomer comprises any one or more of vinylpyridine, β-dimethylaminoethyl acrylate, N-methyl or benzyl(vinylpyridine), N-alkyl or alkaryl-N′-vinylimidazole, and β-(trimethylammonioethyl)acrylate or methacrylate. 
   
   
       7 . An electro-optic assembly according to  claim 1  wherein the electro-optic material comprises a rotating bichromal member or electrochromic material. 
   
   
       8 . An electro-optic assembly 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. 
   
   
       9 . An electro-optic assembly according to  claim 8  wherein the electrically charged particles and the fluid are confined within a plurality of capsules or microcells. 
   
   
       10 . An electro-optic assembly according to  claim 8  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. 
   
   
       11 . An electro-optic display according to  claim 8  wherein the fluid is gaseous. 
   
   
       12 . An electro-optic display, front plane laminate, inverted front plane laminate or double release film comprising an electro-optic assembly according to  claim 1 . 
   
   
       13 . An electronic book reader, portable computer, tablet computer, cellular telephone, smart card, sign, watch, shelf label or flash drive comprising an electro-optic display according to  claim 12 . 
   
   
       14 . An electro-optic assembly comprising an adhesive layer and a layer of electro-optic material, the adhesive layer comprising a polymeric adhesive material which has been subjected to dialysis or diafiltration to remove organic species having a molecular weight less than about 3,500. 
   
   
       15 . An electro-optic assembly comprising an adhesive layer and a layer of electro-optic material, the adhesive layer comprising a polymeric adhesive material having a content of N-methylpyrrolidone not exceeding about 500 ppm based upon the total weight of the adhesive layer and layer of electro-optic material. 
   
   
       16 . An electro-optic assembly according to  claim 15  wherein the polymeric adhesive material comprises a polyurethane. 
   
   
       17 . An electro-optic assembly according to  claim 15  having a content of N-methylpyrrolidone not exceeding about 200 ppm. 
   
   
       18 . An electro-optic assembly according to  claim 17  having a content of N-methylpyrrolidone not exceeding about 100 ppm. 
   
   
       19 . An electro-optic assembly according to  claim 15  wherein the electro-optic material comprises a rotating bichromal member or electrochromic material. 
   
   
       20 . An electro-optic assembly according to  claim 15  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. 
   
   
       21 . An electro-optic assembly according to  claim 20  wherein the electrically charged particles and the fluid are confined within a plurality of capsules or microcells. 
   
   
       22 . An electro-optic assembly according to  claim 20  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. 
   
   
       23 . An electro-optic display according to  claim 20  wherein the fluid is gaseous. 
   
   
       24 . An electro-optic display, front plane laminate, inverted front plane laminate or double release film comprising an electro-optic assembly according to  claim 15 . 
   
   
       25 . An electronic book reader, portable computer, tablet computer, cellular telephone, smart card, sign, watch, shelf label or flash drive comprising an electro-optic display according to  claim 24 . 
   
   
       26 . An electrophoretic medium comprising a continuous phase and a discontinuous phase, the discontinuous phase comprising a plurality of droplets, each of which comprises a suspending fluid and at least one particle disposed within the suspending fluid and capable of moving through the fluid upon application of an electric field to the electrophoretic medium, the continuous phase surrounding and encapsulating the discontinuous phase and comprising a polymeric binder which has been subjected to dialysis or diafiltration to remove organic species having a molecular weight less than about 3,500. 
   
   
       27 . An electrophoretic medium comprising a continuous phase and a discontinuous phase, the discontinuous phase comprising a plurality of droplets, each of which comprises a suspending fluid and at least one particle disposed within the suspending fluid and capable of moving through the fluid upon application of an electric field to the electrophoretic medium, the continuous phase surrounding and encapsulating the discontinuous phase and comprising a polymeric binder having a content of N-methylpyrrolidone not exceeding about 1000 ppm based upon the weight of the electrophoretic medium.