Adhesive and sealing layers for electrophoretic displays
View Patent ↗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.
1. A display device comprising display cells sandwiched between two electrodes layers, wherein the display cells are:
(i) filled with a display fluid wherein charged pigment particles are dispersed in a dielectric solvent, and
(ii) top-sealed with a top-sealing layer formed from a sealing composition comprising a radiation curable composition and a functionalized polyurethane, wherein the functionalized polyurethane has a dielectric constant higher than that of the dielectric solvent and a functional group selected from the group consisting of —OH, —SH, —NCO, —NCS, —NHR, —NRCONHR, —NRCSNHR, vinyl, and epoxide, wherein R is hydrogen or alkyl, aryl, alkylaryl or arylalkyl of up to 20 carbon atoms, wherein the top-sealing layer has a center area and a non-center area, part of the non-center area is adhered to the top portion of the partition wall, the non-center area is thicker than the center area, and the center area is about 1 to about 8 microns in thickness.
2. The display device of claim 1 , wherein said radiation curable composition comprises a multifunctional monomer or oligomer.
3. The display device of claim 1 , wherein said sealing composition further comprises a crosslinking agent.
4. The display device of claim 3 , wherein said sealing composition further comprises a catalyst.
5. The display device of claim 1 , further comprising two electrode layers.
6. The display device of claim 1 , further comprising an electrode layer and a temporary substrate layer.
7. The display device of claim 1 , further comprising a permanent substrate layer and a temporary substrate layer.
8. The display device of claim 1 , further comprising two temporary substrate layers.
9. The display device of claim 8 , wherein said temporary substrate is a release liner.
10. The display device of claim 6 , which is in a form of a roll.
11. The display device of claim 1 , wherein said dielectric solvent is a fluorinated dielectric solvent.
12. The display device of claim 5 , further comprising a protective coating.
13. The display device of claim 12 , wherein said protective coating comprises a particulate additive.
14. The display device of claim 1 , wherein said sealing composition has a specific gravity no greater than that of the display fluid.
15. The display device of claim 1 , wherein said top-sealing layer is being hardened when in contact with the display fluid.
16. The display device of claim 1 , wherein the sealing composition comprises 5-30% of the radiation curable composition and 30-75% of polyurethane, based on dry weight of the top-sealing layer.
17. The display device of claim 1 , wherein the functionalized polyurethane is hydroxyl terminated polyester polyurethane, hydroxyl terminated polyether polyurethanes, isocyanate terminated polyester polyurethanes, isocyanate terminated polyether polyurethanes, acrylate terminated polyester polyurethanes, or acrylate terminated polyether polyurethanes.
18. The display device of claim 1 , wherein the center area is about 3 to about 6 microns in thickness.