Optical diffusing films and methods of making same

Patent metadata

Field	Value
Publication number	US-10295710-B2
Application number	US-201314443407-A
Country	US
Kind code	B2
Filing date	Nov 19, 2013
Priority date	Nov 21, 2012
Publication date	May 21, 2019
Grant date	May 21, 2019

Abstract

Optical diffusing films are made by microreplication from a structured surface tool. The tool is made using a 2-part electroplating process, wherein a first electroplating procedure forms a first metal layer with a first major surface, and a second electroplating procedure forms a second metal layer on the first metal layer, the second metal layer having a second major surface with a smaller average roughness than that of the first major surface. The second major surface can function as the structured surface of the tool. A replica of this surface can then be made in a major surface of an optical film to provide light diffusing properties. The structured surface and/or its constituent structures can be characterized in terms of various parameters such as optical haze, optical clarity, Fourier power spectra of the topography along orthogonal in-plane directions, ridge length per unit area, equivalent circular diameter (ECD), and/or aspect ratio.

First claim

The invention claimed is:

1. A method of making a structured surface, comprising:
forming a first layer of a metal by electrodepositing the metal using a first electroplating process resulting in a first major surface of the first layer having a first average roughness; and
forming a second layer of the metal on the first major surface of the first layer by electrodepositing the metal on the first major surface using a second electroplating process, the second electroplating process including an organic grain refiner, resulting in a second major surface of the second layer having a second average roughness smaller than the first average roughness.

2. The method of claim 1 , further comprising:
providing a base surface having a base average roughness;
wherein the first layer is formed on the base surface, and wherein the first average roughness is greater than the base average roughness.

3. The method of claim 1 , wherein the metal is copper.

4. The method of claim 1 , wherein the first electroplating process uses a first electroplating solution that contains at most trace amounts of an organic leveler.

5. The method of claim 1 , wherein forming the first layer results in the first major surface comprising a plurality of non-uniformly arranged first structures.

6. The method of claim 5 , wherein forming the second layer results in the second major surface comprising a plurality of non-uniformly arranged second structures.

7. The method of claim 6 , further comprising:
forming a third layer of a second metal on the second major surface by electrodepositing the second metal using an electroplating solution of the second metal.

8. The method of claim 7 , wherein the second metal comprises chromium.

9. A microreplication tool made using a method according to claim 1 , such that the microreplication tool has a tool structured surface corresponding to the second major surface.

10. The microreplication tool of claim 9 , wherein the tool structured surface corresponds to an inverted form of the second major surface or a non-inverted form of the second major surface.

Assignees

• 3M Innovative Properties Co

Inventors

• Pham Tri D
• Kong Steven H
• Zhang Haiyan
• Aronson Joseph T
• Leaf Michael R
• Boyd Gary T
• Johnson Nicholas A
• Wang Qingbing

Classifications

• G02F1/133606

  including a specially adapted diffusing, scattering or light controlling members · CPC title

• C25D5/12

  at least one layer being of nickel or chromium · CPC title

• G02B5/0278

  used in transmission · CPC title

• G02B5/0268 Primary

  characterized by the fabrication or manufacturing method · CPC title

• G02B6/0051

  Diffusing sheet or layer · CPC title