Antireflection film

• US 6,464,822 B1
• Filed: 02/19/1998
• Issued: 10/15/2002
• Est. Priority Date: 02/19/1998
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Chia, Yee Ho, Jones, Robert L., Nagarkar, Pradnya V., Choi, Hyung-Chul, Smyth, William K., Wang, Xiaojia Z.
• Primary Examiner(s): DIXON, MERRICK L
• Application Number:
  US09/026,271
• Publication Number:
  US 20020155265A1
• Time in Patent Office: 1,699 Days
• Field of Search: 428/328, 428/336, 428/331, 428/447, 427/164, 427/166, 350/163, 350/165, 156/307.1, 156/307.3, 156/307.4, 156/308.6, 156/314
• US Class Current: 156/307.1
• CPC Class Codes: C08L 27/12 containing fluorine atoms
• CPC Class Codes: C08L 33/08 Homopolymers or copolymers of acrylic acid esters
• CPC Class Codes: C08L 33/10 Homopolymers or copolymers of methacrylic acid esters
• CPC Class Codes: G02B 1/04 made of organic materials, e.g. plastics G02B1/08 takes precedence
• CPC Class Codes: G02B 1/105 Protective coatings
• CPC Class Codes: G02B 1/113 using inorganic layer materials only
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02B 27/0006 with means to keep optical surfaces clean, e.g. by preventing or removing dirt, stains, contamination, condensation G02B1/18 takes precedence; cleaning in general B08B
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/269 including synthetic resin or polymer layer or component

Abstract

An antireflection coating includes one or more inorganic antireflection layers (typically metal oxide or silica layers) and a polymer layer cured in situ, the polymer layer having a refractive index not greater than about 1.53 over the wavelength range of 400 to 700 nm and a thickness of from about 20 to about 200 nm. The polymer layer provides good scratch and fingerprint protection, and also enables the thicknesses of the inorganic antireflection layers to be reduced, thereby reducing the cost of the coating.

Claims

1. A process for providing an antireflection film on a substrate, the process comprising:

depositing an inorganic antireflection layer on the substrate;

depositing a layer of a curable composition on the inorganic antireflection layer; and

effecting free radical curing of the deposited curable composition to form an optically active polymer layer having a thickness of from approximately 20 to approximately 200 nm and a refractive index not greater than approximately 1.53 over the wavelength range of 400 to 700 nm.

2. A process according to claim 1 wherein the inorganic antireflection layer is formed from a metal oxide.

3. A process according to claim 2 wherein the metal oxide is selected from the group consisting of indium oxide, titanium dioxide, cadmium oxide, gallium indium oxide, niobium pentoxide, indium tin oxide, tin dioxide and mixtures thereof.

4. A process according to claim 2 wherein a single layer of the metal oxide having a thickness of from approximately 10 to approximately 30 nm is deposited on the substrate and a polymer layer having a thickness of from approximately 80 to approximately 150 nm is formed on this single metal oxide layer.

5. A process according to claim 4 wherein the metal oxide layer has a thickness in the range of from approximately 17 to approximately 23 nm and the polymer layer has a thickness of from approximately 110 to approximately 130 nm.

6. A process according to claim 2 wherein a first metal oxide is deposited on the substrate;

a silica layer is deposited on the first metal oxide layer;

a second metal oxide layer is deposited on the silica layer, and the polymer layer is formed on the second metal oxide layer.

7. A process according to claim 6 wherein the first metal oxide layer has a thickness of from approximately 20 to approximately 35 nm, the silica layer has a thickness of from approximately 10 to approximately 25 nm, the second metal oxide layer has a thickness of from approximately 50 to approximately 100 nm and the polymer layer has a thickness of from approximately 70 to approximately 120 nm.

8. A process according to claim 7 wherein the first metal oxide layer has a thickness of from approximately 25 to approximately 30 nm, the silica layer has a thickness of from approximately 15 to approximately 20 nm, the second metal oxide layer has a thickness of from approximately 65 to approximately 80 nm and the polymer layer has a thickness of from approximately 85 to approximately 100 nm.

9. A process according to claim 1 wherein the inorganic antireflection layer is formed from silica.

10. A process according to claim 9 wherein a metal oxide layer is deposited upon the substrate, a silica layer is deposited on the metal oxide layer and the polymer layer is formed on the silica layer.

11. A process according to claim 10 wherein the metal oxide layer has a thickness of from approximately 10 to approximately 30 nm, the silica layer has a thickness of from approximately 10 to approximately 120 nm and the polymer layer has a thickness of from approximately 50 to approximately 130 nm.

12. A process according to claim 11 wherein the metal oxide layer has a thickness of from approximately 10 to approximately 20 nm, the silica layer has a thickness of from approximately 10 to approximately 50 nm and the polymer layer has a thickness of from approximately 60 to approximately 100 nm.

13. A process according to claim 1 wherein the polymer layer has a refractive index not greater than approximately 1.50 over the wavelength range of 400 to 700 nm.

14. A process according to claim 1 wherein the curable composition comprises a polymer of a fluoroalkene.

15. A process according to claim 1 wherein the curable composition comprises a polymer of an alkyl acrylate or methacrylate.

16. A process according to claim 1 wherein the curable composition comprises a polyfunctional acrylate monomer.

17. A process according to claim 14 wherein the curable composition comprises both a polymer of a fluoroalkene and a polymer of an alkyl acrylate or methacrylate, and wherein the curing causes segregation of material within the polymer layer, thereby producing a polymer layer having an outer portion enriched in the alkyl acrylate or methacrylate and an inner portion enriched in the fluoroalkene.

18. A process according to claim 1 further comprising depositing a hard coat on the substrate before the inorganic antireflection layer is deposited thereon.

19. A process according to claim 1 wherein the curing of the curable composition is conducted in air.