ANTIREFLECTION FILM

• US 20020155265A1
• Filed: 02/19/1998
• Published: 10/24/2002
• Est. Priority Date: 02/19/1998
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: JONES, ROBERT L., CHIA, YEE HO, CHOI, HYUNG-CHUL, WANG, XIAOJIA Z, SMYTH, WILLIAM K, NAGARKAR, PRADNYA V
• Granted Patent: US 6,464,822 B1
• Time in Patent Office: Days
• US Class Current: 428/212
• 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 comprises 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. An article having an antireflection film, the article comprising a substrate carrying an inorganic antireflection layer and, in contact with the inorganic antireflection layer and forming the outer surface of the antireflection film, a polymer layer formed by curing a curable composition in situ on the inorganic antireflection layer, 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.

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

3. An article according to claim 2 wherein the metal oxide layer comprises at least one of indium oxide, titanium dioxide, cadmium oxide, gallium indium oxide, niobium pentoxide, indium tin oxide and tin dioxide.

4. An article according to claim 3 wherein a single layer of metal oxide, having a thickness of from about 10 to about 30 nm is carried by the substrate and the polymer layer, having a thickness of from about 80 to about 150 nm is carried by the single metal oxide layer.

5. An article according to claim 4 wherein the metal oxide layer has a thickness of from about 17 to about 23 nm and the polymer layer has a thickness of from about 110 to about 130 nm.

6. An article according to claim 2 comprising a first metal oxide layer carried by the substrate;

a silica layer superposed on the first metal oxide layer; and

a second metal oxide layer superposed on the silica layer, the polymer layer being superposed on the second metal oxide layer.

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

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

9. An article according to claim 1 wherein the inorganic antireflection layer is formed from silica.

10. An article according to claim 9 comprising a metal oxide layer carried by the substrate;

and a silica layer superposed on the metal oxide layer, the polymer layer being superposed on the silica layer.

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

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

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

14. An article according to claim 1 wherein the polymer layer comprises repeating units derived from a fluoroalkene.

15. An article according to claim 1 wherein the polymer layer comprises repeating units derived from an alkyl acrylate or methacrylate.

16. An article according to claim 1 wherein the polymer layer comprises repeating units derived from a polyfunctional acrylate monomer.

17. An article according to claim 14 wherein the polymer layer comprises repeating units derived from a fluoroalkene and repeating units derived from an alkyl acrylate or methacrylate, the polymer layer having an outer portion enriched in the alkyl acrylate or methacrylate and an inner portion enriched in the fluoroalkene.

18. An article according to claim 1 further comprising a hard coat disposed between the substrate and the inorganic antireflection layer.

20. A process according to claim 19 wherein the inorganic antireflection layer is formed from a metal oxide.

21. A process according to claim 20 wherein the metal oxide comprises at least one of indium oxide, titanium dioxide, cadmium oxide, gallium indium oxide, niobium pentoxide, indium tin oxide and tin dioxide.

22. A process according to claim 20 wherein a single layer of the metal oxide having a thickness of from about 10 to about 30 nm is deposited on the substrate and a polymer layer having a thickness of from about 80 to about 150 nm is formed on this single metal oxide layer.

23. A process according to claim 22 wherein the metal oxide layer has a thickness in the range of from about 17 to about 23 nm and the polymer layer has a thickness of from about 110 to about 130 nm.

24. A process according to claim 20 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.

25. A process according to claim 24 wherein the first metal oxide layer has a thickness of from about 20 to about 35 nm, the silica layer has a thickness of from about 10 to about 25 nm, the second metal oxide layer has a thickness of from about 50 to about 100 nm and the polymer layer has a thickness of from about 70 to about 120 nm.

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

27. A process according to claim 19 wherein the inorganic antireflection layer is formed from silica.

28. A process according to claim 27 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.

29. A process according to claim 28 wherein the metal oxide layer has a thickness of from about 10 to about 30 nm, the silica layer has a thickness of from about 10 to about 120 nm and the polymer layer has a thickness of from about 50 to about 130 nm.

30. A process according to claim 29 wherein the metal oxide layer has a thickness of from about 10 to about 20 nm, the silica layer has a thickness of from about 10 to about 50 nm and the polymer layer has a thickness of from about 60 to about 100 nm.

31. A process according to claim 19 wherein the polymer layer has a refractive index not greater than about 1.50 over the wavelength range of 400 to 700 nm.

32. A process according to claim 19 wherein the curable composition comprises a polymer of a fluoroalkene.

33. A process according to claim 19 wherein the curable composition comprises a polymer of an alkyl acrylate or methacrylate.

34. A process according to claim 19 wherein the curable composition comprises a polyfunctional acrylate monomer.

35. A process according to claim 32 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.

36. A process according to claim 19 further comprising depositing a hard coat on the substrate before the inorganic antireflection layer is deposited thereon.

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

19. 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 a polymer layer having a thickness of from about 20 to about 200 nm and a refractive index not greater than about 1.53 over the wavelength range of 400 to 700 nm.