Abstract: An adhesive layer is formed by cross-linking an adhesive composition containing: a polyester resin that is a copolymer of a polycarboxylic acid and a polyalcohol; a cross-linking agent; and at least one cross-linking catalyst selected from the group consisting of an organic zirconium compound, an organic iron compound, and an organic aluminum compound, the adhesive layer having a gel fraction of 40% or more after being retained at a temperature of 85° C. and a relative humidity of 85% for 300 hours, and having a 180° peel adhesive strength of 100 mN/20 mm or more with respect to a PMMA film.

Abstract: An optical stack includes: a first optical sheet having a first principal face with a concavo-convex structure and a second principal face at an opposite side from the first principal face; and an adhesive layer that is disposed on the first principal face of the first optical sheet. The concavo-convex structure includes a plurality of dents and flat portions between adjacent ones of the plurality of dents. A surface of the adhesive layer and the first principal face of the first optical sheet together define an internal space within each of the plurality of dents. Each of the plurality of dents satisfies 0.10?(C?A)/C 1.00 and 0.75?(C?A)/(C?B), where A is a maximum height value of the adhesive layer existing in that dent; B is a minimum height value of the adhesive layer existing in that dent; and C is a depth of that dent.

Abstract: An adhesive composition layer is made from an adhesive composition that includes: a polymer including a copolymer of at least one (meth)acrylate monomer and at least one copolymerizable functional group-containing monomer selected from the group consisting of hydroxyl group-containing copolymerizable monomers, carboxyl group-containing copolymerizable monomers, and nitrogen-containing vinyl monomers; and a curable resin. The adhesive composition layer has a 23° C. initial tensile modulus of elasticity of 0.35 MPa or more and yet 8.00 MPa or less before curing the curable resin in the adhesive composition, and a 23° C. initial tensile modulus of elasticity of 1.00 MPa or more after curing the curable resin in the adhesive composition.

Abstract: An adhesive layer (20a) has a creep deformation rate when a stress of 10000 Pa is applied at 50° C. for 1 second is 10% or less, and a creep deformation rate when a stress of 10000 Pa is applied at 50° C. for 30 minutes is 16% or less, in a creep test using a rotational rheometer, and has a 180° peel adhesive strength of 10 mN/20 mm or more with respect to a PMMA film.