Urethane (meth)acrylate oligomer and sheet using the same

A method of producing a display panel with an optical member, the optical member being affixed to the display panel, comprising the steps of:

• preparing a transparent adhesive sheet comprising a photocurable composition layer;
• affixing the optical member to the display panel using the photocurable composition layer of the transparent adhesive sheet,
• wherein the photocurable composition layer is formed from a photocurable composition comprising:
• a urethane (meth)acrylate oligomer,
• the urethane (meth)acrylate oligomer being substantially free of unreacted isocyanate group, the urethane (meth)acrylate oligomer having been obtained by reacting at least one polyoxyalkylene polyol (A), at least one monool (B1) which is soluble in the component (A) and/or at least one silane coupling agent (B2) which can react with isocyanate group, at least one polyisocyanate (C), and at least one hydroxy group-containing mono (meth) acrylate compound (D) at a ratio so that the equivalent weights of the hydroxy group, active hydrogen group, and isocyanate group of the respective components satisfy the following formulae (1) to (3):
• B(active hydrogen)+D(OH)=C(NCO)−A(OH) (1)
• 1.05≦C(NCO)/A(OH)≦2 (2)
• {C(NCO)−2A(OH)+2m}×0.35≦D(OH)≦{C(NCO)−2A(OH)+2m}×0.70 (3)
• wherein in the formulae (1) to (3), A(OH) represents the total equivalent weight of the hydroxy group of the component (A), B(active hydrogen) represents the total equivalent weight of the active hydrogen group of the component (B1) and/or (B2), C(NCO) represents the total equivalent weight of the total equivalent weight of the isocyanate group of the component (C), and D (OH) represents the total equivalent weight of the hydroxy group of the component (D), and m represents the number of moles of the component (A).