Optical film coating

• US 20060008596A1
• Filed: 07/09/2004
• Published: 01/12/2006
• Est. Priority Date: 07/09/2004
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Pokorny, Richard J., Yapel, Robert A., Balich, Jason W.
• Granted Patent: US 7,378,136 B2
• Time in Patent Office: Days
• US Class Current: 428/1.100
• CPC Class Codes: C08J 7/0427 with only one layer of a composition containing a polymer binder with more layers C08J7/042
• CPC Class Codes: C08J 7/043 Improving the adhesiveness of the coatings per se, e.g. forming primers adhesives in the form of films or foils characterised by the primer layers between the polymer carriers and the adhesives C09J7/50
• CPC Class Codes: C08J 7/046 Forming abrasion-resistant coatings; Forming surface-hardening coatings
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• CPC Class Codes: C09K 2323/03 Viewing layer characterised by chemical composition
• CPC Class Codes: C09K 2323/035 Ester polymer, e.g. polycarbonate, polyacrylate or polyester
• CPC Class Codes: G02B 1/10 Optical coatings produced by application to, or surface treatment of, optical elements G02B1/08 takes precedence
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02B 5/0808 having a single reflecting layer G02B5/0883, G02B5/0891 take precedence
• CPC Class Codes: G02B 5/0883 with a refractive index gradient rugate filters G02B5/289

Abstract

A low fringing film coating includes a transparent polymeric layer having a surface, and a plurality of projections extending away from the surface. The projections have a mean height of 0.05 to 1 μm and a mean distance between projections of 0.5 to 2 mm. The coating can be produced by coating a polymeric composition onto a substrate. The polymeric composition includes a polymeric material, a good solvent for the polymeric material and a poor solvent or the polymeric material. The solvents are at least partially evaporated to form a low fringing transparent polymeric layer.

Claims

1. An optical film comprising:

a transparent polymeric layer having a surface; and

a plurality of projections extending away from the surface, the projections having a mean height of 0.05 to 1 μ

m and a mean distance between projections of 0.5 to 2 mm.

2. The optical film according to claim 1, wherein the transparent polymeric layer has a thickness of 2 to 10 μ

m.

3. The optical film according to claim 1, wherein the transparent polymeric layer comprises inorganic particles having an average particle diameter of 5 to 75 nm.

4. The optical film according to claim 3, wherein the inorganic particles comprise silica particles.

5. The optical film according to claim 3, wherein the transparent polymeric layer comprises 10 to 100 phr inorganic particles.

7. The optical film according to claim 1, wherein the transparent polymeric layer is formed from a polymer material, a C₇ to C₁₂ alkane, and a polar solvent.

8. The optical film according to claim 1, wherein the transparent polymeric layer comprises a polyacrylate.

9. The optical film according to claim 1, wherein the transparent polymeric layer is disposed on a substrate having a first refractive index, the transparent polymeric layer has a second refractive index and the first refractive index differs from the second refractive index by a value from 0.05 to 0.2.

6. The optical film according to claim f, wherein the plurality of projections are randomly located on the surface.

10. A method of forming a low fringing film comprising steps of:

coating a polymeric composition onto a substrate, the polymeric composition comprising a polymeric material, a polar solvent and a non-polar solvent; and

evaporating at least a portion of the polar solvent and the non-polar solvent to form a transparent polymeric layer;

wherein, the transparent polymeric layer has a surface and a plurality of projections that extend away from the surface, the projections having a mean height of 0.05 to 1 μ

m and a mean distance between projections of 0.5 to 2 mm.

11. The method according to claim 10, wherein the coating step comprises coating a polymeric composition onto a substrate, the polymeric composition comprising a polymeric material having a first Hildebrand'"'"'s solubility parameter, a polar solvent, and a non-polar solvent having a second Hildebrand'"'"'s solubility parameter, the first Hildebrand'"'"'s solubility parameter differs from the second Hildebrand'"'"'s solubility parameter by a value of at least 2.

12. The method according to claim 10, wherein the coating step comprises coating a polymeric composition onto a substrate, the polymeric composition comprising a polymeric material having a first Hildebrand'"'"'s solubility parameter, a polar solvent, and a non-polar solvent having a second Hildebrand'"'"'s solubility parameter, the first Hildebrand'"'"'s solubility parameter differs from the second Hildebrand'"'"'s solubility parameter by a value of at least 3.

13. The method according to claim 10, wherein the coating step comprises coating a polymeric composition onto a substrate, the polymeric composition comprising a polymeric material, a polar solvent and a non-polar solvent comprising a C₇ to C₁₂ alkane.

14. The method according to claim 10, wherein the coating step comprises coating a polymeric composition onto a substrate, the polymeric composition comprising a polymeric material, a polar solvent having a first boiling point and a non-polar solvent having a second boiling point, wherein the second boiling point is 25°

C. or greater than the first boiling point.

15. The method according to claim 10, wherein the coating step comprises coating a polymeric composition onto a substrate, the polymeric composition further comprising inorganic particles having an average particle diameter of 5 to 75 nm.

16. The method according to claim 15, wherein the coating step comprises coating a polymeric composition onto a substrate, the polymeric composition further comprising 10 to 100 phr inorganic particles.

17. The method according to claim 10, wherein the coating step comprises coating a polymeric composition onto a substrate, the polymeric composition comprising 1 to 100 phr of the non-polar solvent.

18. The method according to claim 10, wherein the coating step comprises coating a polymeric composition onto a substrate, the polymeric composition comprising 20 to 85 phr of the non-polar solvent comprising a C₈ to C₁₂ alkane.

19. The method according to claim 10, wherein the substrate has a first refractive index, the transparent polymeric layer has a second refractive index and the first refractive index differs from the second refractive index by a value from 0.05 to 0.2.

20. A method of forming a low fringing film comprising steps of:

coating a polymeric composition onto a substrate, the polymeric composition comprising a polymeric material, a good solvent for the polymeric material and a poor solvent for the polymeric material, the polymeric material having a first Hildebrand'"'"'s solubility parameter, the poor solvent having a second Hildebrand'"'"'s solubility parameter, the first Hildebrand'"'"'s solubility parameter differs from the second Hildebrand'"'"'s solubility parameter by a value of at least 2;

evaporating at least a portion of the good solvent and the poor solvent to form a transparent polymeric layer;

wherein, the transparent polymeric layer has a surface and a plurality of projections that extend away from the surface, the projections having a mean height of 0.05 to 1 μ

m and a mean distance between projections of 0.5 to 2 mm.

21. The method according to claim 20, wherein the coating step comprises coating a polymeric composition onto a substrate, the polymeric composition further comprising inorganic particles having an average particle diameter of 5 to 75 nm.

22. The method according to claim 20, wherein the coating step comprises coating a polymeric composition onto a substrate, the polymeric composition comprising a polymeric material having a first Hildebrand'"'"'s solubility parameter and a poor solvent having a second Hildebrand'"'"'s solubility parameter, the first Hildebrand'"'"'s solubility parameter differs from the second Hildebrand'"'"'s solubility parameter by a value of at least 3.

23. The method according to claim 20, wherein the coating step comprises coating the polymeric composition onto a substrate, the polymeric composition comprising a polymeric material, a good solvent for the polymeric material having a first boiling point and a poor solvent for the polymeric material having a second boiling point, wherein the second boiling point is 25°

C. or greater than the first boiling point.

24. The method according to claim 20, wherein the evaporating step comprises evaporating at least a portion of the good solvent and the poor solvent to form a transparent polymeric layer having a thickness from 2 to 10 μ

m.

25. The method according to claim 20, wherein the substrate has a first refractive index, the transparent polymeric layer has a second refractive index and the first refractive index differs from the second refractive index by a value from 0.05 to 0.2.

26. The method according to claim 20, wherein the coating step comprises coating a polymeric composition onto an optical element.

27. An optical display comprising:

an optical element;

a display housing disposed about the optical element; and

a transparent polymeric layer disposed adjacent the optical element, the transparent polymeric layer having a surface, and the transparent polymeric layer having a plurality of projections extending away from the surface, the projections having a mean height of 0.05 to 1 μ

m and a mean distance between projections of 0.5 to 2 mm.

28. An optical display according to claim 27, wherein the optical element comprises a liquid crystal substrate.