Optical film, antireflection film, and polarizing plate and display device using the same

1. An optical film comprising:

a transparent support; and

a hardcoat layer that is a layer formed by curing a coating solution, the coating solution comprising (A) an octa- to pentadeca-functional urethane (meth)acrylate-based compound having a molecular weight of 800 to 1,363 and having two or more urethane bonds in its molecule; and a photopolymerization initiator.

2. The optical film according to claim 1 , wherein

the compound (A) is a compound synthesized by reacting an additive compound of an isocyanate compound and an active hydrogen-containing compound, with a compound having a (meth)acryloyl group and a reactive group.

3. The optical film according to claim 2 , wherein

the active hydrogen-containing compound is a polyol.

4. The optical film according to claim 1 , wherein

the hardcoat layer is a light-diffusing hardcoat layer comprising a light-transparent particle or a transparent hardcoat layer not comprising a light-transparent particle.

5. The optical film according to claim 1 , wherein

the hardcoat layer comprises the compound (A); and a trifunctional or greater polyfunctional (meth)acrylate compound.

6. An antireflection film comprising:

the optical film according to claim 1 ; and

a layer, on the hardcoat layer of the optical film, having a refractive index lower than that of the hardcoat layer.

7. A polarizing plate comprising:

a pair of protective films; and

a polarizing film sandwiched between the pair of protective films,

wherein

at least one of the protective films is the optical film according to claim 1 .

8. A display device comprising:

the optical film according to claim 1 ,

wherein

the hardcoat layer of the optical film is disposed on a viewing side.