Structure, production method thereof, and article provided with said structure
A structure with a substrate, and a fine-unevenness-structure layer provided to at least one surface of the substrate, wherein the fine-unevenness-structure layer is disposed at a surface of the structure, the indentation elastic modulus of the structure is 1-1300 MPa, and the ratio (Δμ) of the rate of change of the coefficient of kinetic friction of the surface of the structure is 0.15-1.05, wherein Δμ=Δμf/Δμs: Δμs represents the rate of change of the coefficient of kinetic friction of the surface of the structure at an initial-abrasion stage of a reciprocating abrasion test; and Δμf represents the rate of change of the coefficient of kinetic friction of the surface of the structure immediately prior to the end of the reciprocating abrasion test. This structure exhibits excellent scratch resistance without compromising on the optical performance thereof, such as the antireflection performance.
1. A structure comprising a substrate and a fine concavo-convex structure layer provided on at least one face of the substrate,
the fine concavo-convex structure layer being disposed on the surface of the structure and having an indentation modulus of 1 MPa to 1300 MPa and a ratio of the rates of change (Δμ) in the coefficient of kinetic friction of the surface of the structure represented by the following Formula (1), of 0.15 to 1.05:
Δμ=Δμ f/Δμs (1)
wherein in Formula (1), Δμs represents the rate of change in the coefficient of kinetic friction in the stage of initial wear in a reciprocating abrasion test of the fine concavo-convex structure layer surface; and Δμf represents the rate of change in the coefficient of kinetic friction immediately before the end of the test in the reciprocating abrasion test.
2. The structure according to claim 1 , wherein the average interval between adjoining convexities in the fine concavo-convex structure layer is 400 nm or less, and the aspect ratio of the convexities is 0.7 to 1.4.
3. The structure according to claim 1 , wherein the average interval between adjoining convexities of the fine concavo-convex structure layer is 120 nm to 250 nm.
4. The structure according to claim 1 , wherein the fine concavo-convex structure layer contains a cured product of an active energy ray-curable resin composition, and the active energy ray-curable resin composition includes at least a (meth)acrylate having an oxyethylene group.
5. The structure according to claim 1 , wherein the ratio of the rates of change in the coefficient of kinetic friction of the fine concavo-convex structure layer surface represented by Formula (1) is 0.3 to 1.0.
6. The structure according to claim 1 , wherein the ratio of the rates of change in the coefficient of kinetic friction of the fine concavo-convex structure layer surface represented by Formula (1) is 0.6 to 0.9.
7. The structure according to claim 1 , wherein the coefficient of kinetic friction of the fine concavo-convex structure layer surface is 0.55 or less.
8. The structure according to claim 1 , wherein the coefficient of kinetic friction of the fine concavo-convex structure layer surface is 0.38 to 0.5.
9. The structure according to claim 1 , wherein the indentation modulus of the fine concavo-convex structure layer is 160 MPa to 300 MPa.
10. The structure according to claim 1 , further comprising an intermediate layer between the substrate and the fine concavo-convex structure layer.
11. The structure according to claim 10 , wherein the intermediate layer contains a cured product of an active energy ray-curable resin composition, and the active energy ray-curable resin composition includes at least one (meth)acrylate selected from the group consisting of an ester (meth)acrylate and a urethane (meth)acrylate.
12. The structure according to claim 1 , wherein the substrate is a light-transmitting substrate.
13. An article comprising the structure according to claim 1 .
14. A method for producing the structure according to claim 1 , the method comprising a step of forming a fine concavo-convex structure layer by a nanoimprint method.