Patent ID: 8871313

Claim:
A prism sheet suitable for use in a backlight unit assembly, said prism sheet comprising: a base layer; and a resin cured layer having at least one structured surface, said structured surface being provided with multiple structures, wherein the resin comprises a molecular chain containing a slippable chemical element, and a UV curable composition comprising a urethane acrylate oligomer obtained from a urethane prepolymer, wherein the ratio of a hard segment to a soft segment in the urethane prepolymer is 1:1.32 to 1:3.9; and wherein the prism sheet has an elastic recovery rate of 90% or more, which is represented by Mathematical Formula 1 below when the structured surface of the resin cured layer is pressed to a maximum compression force of 1 g f at a pressing speed of 0.2031 mN/sec using a flat indenter, and then the pressing of the structured surface thereof is stopped for 5 seconds with it compressed, and then released: Elasticrecoveryrate = D ⁢ ⁢ 1 - D ⁢ ⁢ 2 D ⁢ ⁢ 1 × 100 Mathematical ⁢ ⁢ Formula ⁢ ⁢ 1 wherein D 1 is a depth of the prism sheet compressed by external pressure, and D 2 is a difference between the height of the prism sheet to which external pressure is not applied and the height of the prism sheet which is recovered by removing the external pressure.