▎ 摘　　要

NOVELTY - Sealing layer comprises 30-70 wt.% water soluble poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer by weight of the sealing layer excluding solvents, poly(vinyl alcohol) having a degree of hydrolysis 90-99.9%, and poly(vinyl alcohol-co-ethylene) copolymer having a degree of hydrolysis of from 90-99.9% and ethylene content of less than 10 wt.%, 7-29 wt.% polyurethane by weight of the sealing layer excluding solvents, 1-45 wt.% conductive filler by weight of the sealing layer excluding solvents. The conductive filler is selected from the group consisting of carbon black, graphene, graphite, and carbon nanotubes. USE - Sealing layers for sealing microcells of electro-optic devices, such as electrophoretic displays. ADVANTAGE - The sealing layers have low resistivity lead to inferior image resolution. The polymer compositions form optimized sealing layers for improved barrier towards non-polar fluids, reduced moisture absorption, and optimal electrical resistivity. The aqueous polymer compositions comprising poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer, polyurethane, and a conductive filler, forms sealing layers with surface energy in a specific range, lead to excellent electro-optic performance. DETAILED DESCRIPTION - Sealing layer comprises 30-70 wt.% water soluble poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer by weight of the sealing layer excluding solvents, 90-99.9 wt.% poly(vinyl alcohol) having a degree of hydrolysis, and poly(vinyl alcohol-co-ethylene) copolymer having a degree of hydrolysis of from 90-99.9% and ethylene content of less than 10 wt.%, 7-29 wt.% polyurethane by weight of the sealing layer excluding solvents, 1-45 wt.% conductive filler by weight of the sealing layer excluding solvents. The conductive filler is selected from the group consisting of carbon black, graphene, graphite, and carbon nanotubes. The conductive filler having a total surface energy, where total surface energy being higher than 40 milliNewton/meter (mN/m), the total surface energy of the conductive filler being determined by the Washburn method, using hexane as test liquid. The sealing layer having a total surface energy, the total surface energy of the sealing layer being higher than 55 mN/m, the total surface energy of the sealing layer being determined using the Contact Angle Method by forming the sealing layer by coating an aqueous polymer composition on a substrate at a dry thickness of 30 millimeters (mm). Then, heated at 100℃ for 15 minutes, and the sealing layer is conditioned at 25℃ and 55% relative humidity for 24 hours. The contact angles of a water droplet and a diiodomethane droplet are measured on the formed sealing layer. The total surface energy is calculated using the Owens, Wendt, Rabel and Kaelble (OWRK) model. An INDEPENDENT CLAIM is included for an electrophoretic display, which comprises a first light-transmissive electrode layer, an electro-optic material layer comprising a sealing layer and a set of microcells, each of the multiple microcells including a bottom, walls, and an opening, and containing an electrophoretic medium, electrophoretic medium comprising at least one type of charged pigment particles dispersed in a non-polar fluid, the sealing layer spanning the openings of the multiple microcells, a second electrode layer, the electro-optic material layer being disposed between the first light-transmissive electrode layer and the second electrode layer.