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US 8,939,752 B2Granted
Mold, process for producing mold, and process for producing sheet
AssigneesMitsubishi Rayon Co., Ltd., Kanagawa Academy of Science and Technology
InventorsYoshihiro Uozu, Eiko Okamoto, Katsuhiro Kojima, Satoshi Sakuma, Hideki Masuda, Takashi Yanagishita
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Abstract
A mold comprising alumina having a microscopic pattern, in which distances between adjacent recesses or salients therein are not longer than wavelength of visible light, formed by anodic oxidation on a surface of an aluminum pre-mold without a rolling mark, wherein height or depth difference at a crystal grain boundary is 300 nm or less.
Claims21
A large area alumina mold having a microscopic pattern, the mold prepared by a process comprising steps of:
- preparing a pre-mold by polishing an aluminum plate free from a rolling mark or by forming an aluminum film on a substrate surface;
- forming a first oxide film by subjecting surface aluminum of the pre-mold to a first anodic oxidation for a time adjusted to provide said first oxide film with a thickness of 10 μm or less;
- removing the first oxide film so as to leave regular pore originating points on a surface of remaining pre-mold aluminum;
- forming pores from the originating points by subjecting the surface of remaining pre-mold aluminum to a second anodic oxidation forming a second oxide film;
- removing a part of the second oxide film so as to enlarge pore diameter;
- and
- repeating the second anodic oxidation and the pore diameter enlargement so as to form regularly arranged tapered pores decreasing in diameter from a top surface thereof,
- wherein relative distances between adjacent pores of the alumina mold are not longer than a wavelength of visible light.
5 more elements
Dependencies are inferred from the claim text.