Mold having an uneven surface structure, optical article, manufacturing method therefor, transparent substrate for surface light emitter and surface light emitter
The invention relates to a mold having an irregularly uneven surface structure in which an average inclination angle is from 20 to 80 degrees; an optical article having an irregularly uneven surface structure in which an average inclination angle is from 20 to 80 degrees; a method for manufacturing an optical article having an irregularly uneven surface structure by transferring an uneven structure of a mold; a transparent substrate for a surface light emitter which uses an optical article having an irregularly uneven surface structure; and a surface light emitter having a transparent substrate for a surface light emitter.
1. A method for manufacturing an optical article having an uneven surface structure comprising:
placing an active energy ray curable resin composition between a mold having an uneven surface structure, wherein an average inclination angle obtained is from 20 to 80 degrees, and a diffusion factor obtained is 5 to 80%, or a replica mold having the uneven structure of the mold transferred on a surface of a replica mold substrate, and a substrate for an optical article;
forming, on a surface of the substrate for an optical article, an uneven resin layer transferred with the uneven structure of the mold or the replica mold by irradiating the active energy ray curable resin composition with active energy ray to cure the active energy ray curable resin composition; and
releasing the optical article having the uneven resin layer and the substrate for an optical article from the mold or the replica mold;
wherein:
the average inclination angle is defined by:
collecting a photographic image of an uneven structure for the length L (10 μm), which is a standard length in direction x perpendicular to height direction y of the uneven structure, from a cross-sectional photographic image of a mold taken by a scanning electron microscope,
digitalizing the collected photographic image of the uneven structure,
transforming a ridge line of the uneven structure into an xy coordinate,
obtaining an average inclination angle θa from the obtained coordination data of the ridge line (y=f(x)) by the following equation
θ
a
=
tan
-
1
(
1
L
∫
ⅆ
f
(
x
)
ⅆ
x
ⅆ
x
)
,
wherein the average inclination angle θa is obtained similarly for 20 spots in total, an average value of which is obtained, and
wherein the diffusion factor as obtained by the method described below is 5 to 80%:
in a height direction of an uneven structure, laser light is applied to an optical article; intensity I θ of transmitted diffusion light, which is emitted after transmission through an optical article, is measured; from the intensity when exit angle θ is 5 degrees, 20 degrees, and 70 degrees, a diffusion factor D is obtained by the following equation
D
=
(
B
70
+
B
20
)
/
2
B
5
×
100
B
0
=
I
0
/
cos
θ
.
2. An optical article having an uneven surface structure which is manufactured by the manufacturing method according to claim 1 .
3. The method for manufacturing an optical article having an uneven surface structure according to claim 1 ,
wherein the irregularly uneven surface structure is a plating film of a metal selected from the group consisting of nickel, nickel alloy, copper, and copper alloy.
4. The method for manufacturing an optical article having an uneven surface structure according to claim 1 ,
wherein
the active energy ray curable resin composition comprises polybutylene glycol di(meth)acrylate.
5. The method for manufacturing an optical article having an uneven surface structure according to claim 1 , wherein the plurality of needle-like protrusions are irregularly formed on the surface of the mold.
6. The method for manufacturing an optical article having an uneven surface structure according to claim 1 , wherein the uneven structure comprises a metal.
7. The method for manufacturing an optical article having an uneven surface structure according to claim 6 , wherein the metal is nickel, a nickel alloy, copper, or a copper alloy.
8. The method for manufacturing an optical article having an uneven surface structure according to claim 6 , wherein the uneven surface structure has a total reflectance of 1 to 30% from a surface on the side having the uneven structure as measured using a light source C according to JIS K 7105.
9. The method for manufacturing an optical article having an uneven surface structure according to claim 1 , wherein the metal is nickel, a nickel alloy, copper, or a copper alloy.
10. The method for manufacturing an optical article having an uneven surface structure according to claim 1 , wherein the uneven surface structure is constituted with a plurality of needle-like protrusions including a metal.
11. The method for manufacturing an optical article having an uneven surface structure according to claim 10 , wherein the metal is nickel, a nickel alloy, copper, or a copper alloy.