Abstract: A photocurable composition comprising the following components (A) to (D): (A) at least one of the (meth)acrylates having the structures shown by the formulas (1) and (2), wherein R1 represents a hydrogen atom or a halogen atom excluding a fluorine atom, R2 is a hydrogen atom, a halogen atom excluding a fluorine atom, Ph-C(CH3)2—, Ph-, or an alkyl group having 1-20 carbon atoms, and R3 represents —CH2—, —S—, or —C(CH3)2—; (B) a (meth)acrylate having three or more functional groups, excluding the (meth)acrylates of the component (A); (C) a radical photoinitiator; and (D) a polycarbonate polyol having a hydroxyl value of 10-100; wherein 5-50 wt % of the total acrylic components in the composition are methacrylate compounds. A photocurable composition produces a cured product possessing a high refractive index, excelling in heat resistance, showing only a small amount of warping, and being particularly useful as an optical part such as a prism lens sheet.

Abstract: To provide a photocurable liquid resin composition that can produce cured products exhibiting a high refractive index, good shape restorability, and superior adhesion to substrates. The photocurable resin composition comprises (A) 20-80 wt % of a urethane (meth) acrylate obtained by reacting a polyether polyol having an alkyleneoxy structure in the molecule, an organic polyisocyanate compound, and a (meth) acrylate containing a hydroxyl group, (B) 10-70 wt % of a monofunctional ethylenically unsaturated compound, (C) 5-25 wt % of a (meth) acrylate monomer having four or more functional groups, and (D) 0.1-10 wt % of a photoinitiator. Cured products are useful for forming an optical part such as a lens of a lens sheet or a back light using the lens sheet.