DURABLE ANTI-REFLECTIVE ARTICLES

• US 20150322270A1
• Filed: 05/08/2015
• Published: 11/12/2015
• Est. Priority Date: 05/12/2014
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Amin, Jaymin, Hart, Shandon Dee, Koch, Karl William III, Ouyang, Xu, Paulson, Charles Andrew, Price, James Joseph, Null, Eric Louis
• Granted Patent: US 11,267,973 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C03C 17/3417 all coatings being oxide coatings
• CPC Class Codes: C03C 17/3435 comprising a nitride, oxynitride, boronitride or carbonitride
• CPC Class Codes: C03C 21/002 to perform ion-exchange between alkali ions C03C21/005 takes precedence
• CPC Class Codes: C03C 2217/734 comprising an alternation of high and low refractive indexes
• CPC Class Codes: C03C 2217/78 Coatings specially designed to be durable, e.g. scratch-resistant
• CPC Class Codes: C09D 5/006 Anti-reflective coatings
• CPC Class Codes: G02B 1/115 Multilayers
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/265 1 mil or less

Abstract

Embodiments of durable, anti-reflective articles are described. In one or more embodiments, the article includes a substrate and an anti-reflective coating disposed on the major surface. The article exhibits an average light transmittance of about 94% or greater over an optical wavelength regime and/or an average light reflectance of about 2% or less over the optical wavelength regime, as measured from an anti-reflective surface. In some embodiments, the article exhibits a maximum hardness of about 8 GPa or greater as measured by a Berkovich Indenter Hardness Test along an indentation depth of about 50 nm or greater and a b* value, in reflectance, in the range from about −5 to about 1 as measured on the anti-reflective surface only at all incidence illumination angles in the range from about 0 degrees to about 60 degrees under an International Commission on Illumination illuminant.

Claims

1. An article comprising:

a substrate having a major surface; and

an anti-reflective coating having a thickness of about 1 μ

m or less disposed on the major surface, the anti-reflective coating comprising an anti-reflective surface,

wherein the article exhibits a maximum hardness of about 8 GPa or greater as measured by a Berkovich Indenter Hardness Test along an indentation depth of about 50 nm or greater;

wherein the article exhibits either one or both of;

a single side average light transmittance of about 94% or greater over an optical wavelength regime and

a single side light reflectance of about 2% or less over the optical wavelength regime, and

wherein the article exhibits a b* value, in reflectance, in the range from about −

5 to about 1 as measured on the anti-reflective surface only at all incidence illumination angles in the range from about 0 degrees to about 60 degrees.

2. The article of claim 1, wherein the b* value is measured under an F2 illuminant.

3. The article of claim 1, wherein the article exhibits

article transmittance color coordinates in the (L*, a*, b*) colorimetry system at normal incidence under an International Commission on Illumination illuminant exhibiting a reference point color shift of less than about 2 from a reference point as measured at the anti-reflective surface, the reference point comprising at least one of the color coordinates (a*=0, b*=0) and the transmittance color coordinates of the substrate, and

article reflectance color coordinates in the (L*, a*, b*) colorimetry system at normal incidence under an International Commission on Illumination illuminant exhibiting a reference point color shift of less than about 5 from a reference point as measured at the anti-reflective surface, the reference point comprising at least one of the color coordinates (a*=0, b*=0), the color coordinates (a*−

2, b*=−

2) and the reflectance color coordinates of the substrate,

wherein, when the reference point is the color coordinates (a*=0, b*=0), the color shift is defined by √

((a*_article)²+(b*_article)²),

wherein, when the reference point is the color coordinates (a*=−

2, b*=−

2), the color shift is defined by √

(a*_article+2)²+(b*_article+2)²), and

wherein, when the reference point is the color coordinates of the substrate, the color shift is defined by √

((a*_article−

a*_substrate)²+(b*_article−

b*_substrate)²).

4. The article of claim 1, wherein the article exhibits an abrasion resistance comprising about 1% haze or less, as measured using a hazemeter having an aperture, wherein the aperture has a diameter of about 8 mm, and

wherein the abrasion resistance is measured after a 500-cycle abrasion using a Taber Test.

5. The article of claim 1, wherein the article exhibits an abrasion resistance comprising an average roughness Ra, as measured by atomic force microscopy, of about 12 nm or less, and

wherein the abrasion resistance is measured after a 500-cycle abrasion using a Taber Test.

6. The article of claim 1, wherein the article exhibits an abrasion resistance comprising a scattered light intensity of about 0.05 (in units of 1/steradian) or less, at a polar scattering angle of about 40 degrees or less, as measured at normal incidence in transmission using an imaging sphere for scatter measurements, with a 2 mm aperture at 600 nm wavelength, and

wherein the abrasion resistance is measured after a 500-cycle abrasion using a Taber Test.

7. The article of claim 1, wherein the article exhibits an abrasion resistance comprising a scattered light intensity of about 0.1 (in units of 1/steradian) or less, at a polar scattering angle of about 20 degrees or less, as measured at normal incidence in transmission using an imaging sphere for scatter measurements, with a 2 mm aperture at 600 nm wavelength, and

wherein the abrasion resistance is measured after a 500-cycle abrasion using a Taber Test.

8. The article of claim 1, wherein the anti-reflective coating comprises a plurality of layers, the plurality of layers comprising a first low RI layer, a second high RI layer and an optional third layer.

9. The article of claim 8, wherein at least one of the first low RI layer and the second high RI layer comprises an optical thickness (n*d) in the range from about 2 nm to about 200 nm.

10. The article of claim 1, wherein the anti-reflective coating comprises a thickness of about 800 nm or less.

11. The article of claim 1, wherein the article exhibits a reflectance angular color shift of less than about 5, as measured on the anti-reflective surface, at all angles from normal incidence to an incident illumination angle in the range from about 20 degrees to about 60 degrees under a F2 illuminant, and wherein angular color shift is calculated using the equation √

(a*₂−

a*₁)²+(b*₂-b*₁)²), with a*₁, and b*₁ representing the coordinates of the article when viewed at normal incidence and a*₂, and b*₂ representing the coordinates of the article when viewed at the incident illumination angle.

12. The article of claim 1, exhibiting a reflectance spectra such that the maximum reflectance over a wavelength range from about 400 nm to about 480 nm (R400-max) is greater than the maximum reflectance over a wavelength range from about 500 nm to about 600 nm (R500-max) and the maximum reflectance over a wavelength range from about 640 nm to about 710 (R640-max), and

wherein the minimum reflectance over a wavelength range from about 400 nm to about 480 nm (R400-min) is optionally less than the minimum reflectance over a wavelength range from about 500 nm to about 600 nm (R500-min), and

wherein the minimum reflectance over a wavelength range from about 640 to about 710 (R640-min) is optionally less than R500-min.

13. The article of claim 8, wherein anti-reflective coating comprises a physical thickness and a plurality of second high RI layers comprising a nitride or an oxynitride, and wherein the combined physical thickness of the second high RI layers is 40% or greater of the physical thickness of the anti-reflective coating.

14. The article of claim 1, wherein the substrate comprises an amorphous substrate or a crystalline substrate.

15. The article of claim 14, wherein the amorphous substrate comprises a glass selected from the group consisting of soda lime glass, alkali aluminosilicate glass, alkali containing borosilicate glass and alkali aluminoborosilicate glass.

16. The article of claim 15, wherein the glass is chemically strengthened and comprises a compressive stress (CS) layer with a surface CS of at least 250 MPa extending within the chemically strengthened glass from a surface of the chemically strengthened glass to a depth of layer (DOL) of at least about 10 μ

m.

17. The article of claim 1, further comprising any one or more of an easy-to-clean coating, a diamond-like carbon coating, and a scratch resistant coating, disposed on the anti-reflective coating.

18. An article comprising:

a substrate having a major surface; and

an anti-reflective coating having a thickness of about 1 μ

m or less disposed on the major surface, the anti-reflective coating comprising an anti-reflective surface,

wherein the article exhibits a maximum hardness of about 8 GPa or greater as measured by a Berkovich Indenter Hardness Test along an indentation depth of about 50 nm or greater;

wherein the article exhibits either one or both of;

a single side average light transmittance of about 94% or greater over an optical wavelength regime and

a single side light reflectance of about 2% or less over the optical wavelength regime,

wherein the article exhibits a reflectance angular color shift of less than about 5, as measured on the anti-reflective surface from normal incidence to an incident illumination angle in the range from about 2 degrees to about 60 degrees under a D65 illuminant or F2 illuminant, wherein angular color shift is calculated using the equation √

((a*₂−

a*₁)²+(b*₂−

b*₁)²), with a*₁, and b*₁ representing the coordinates of the article when viewed at normal incidence and a*₂, and b*₂ representing the coordinates of the article when viewed at the incident illumination angle, and

wherein the article exhibits either one or both

article transmittance color coordinates in the (L*, a*, b*) colorimetry system at normal incidence the D65 or F2 illuminant exhibiting a reference point color shift of less than about 2 from a reference point as measured at the anti-reflective surface, the reference point comprising at least one of the color coordinates (a*=0, b*=0) and the transmittance color coordinates of the substrate, and

article reflectance color coordinates in the (L*, a*, b*) colorimetry system at normal incidence exhibiting a color shift of less than about 5 from a reference point as measured at the anti-reflective surface, the reference point comprising at least one of the color coordinates (a*=0, b*=0), the coordinates (a*=−

2, b*=−

2), and the reflectance color coordinates of the substrate,

wherein, when the reference point is the color coordinates (a*=0, b*=0), the color shift is defined by √

(a*_article)²+(b*_article)²),

wherein, when the reference point is the color coordinates (a*=−

2, b*=−

2), the color shift is defined by √

(a*_article+2)²+(b*_article+2)²), and

wherein, when the reference point is the color coordinates of the substrate, the color shift is defined by √

(a*_article−

a*_substrate)²+(b*_article−

b*_substrate)²).

19. The article of claim 18, wherein the article exhibits an abrasion resistance comprising any one of

about 1% haze or less, as measured using a hazemeter having an aperture, wherein the aperture has a diameter of about 8 mm,

an average roughness, as measured by atomic force microscopy, of about 12 nm RMS or less,

a scattered light intensity of about 0.05 (in units of 1/steradian) or less, at a polar scattering angle of about 40 degrees or less, as measured at normal incidence in transmission using an imaging sphere for scatter measurements, with a 2 mm aperture at 600 nm wavelength, and

a scattered light intensity of about 0.1 (in units of 1/steradian) or less, at a polar scattering angle of about 20 degrees or less, as measured at normal incidence in transmission using an imaging sphere for scatter measurements, with a 2 mm aperture at 600 nm wavelength,

wherein the abrasion resistance is measured after a 500-cycle abrasion using a Taber Test.

20. The article of claim 18, wherein the anti-reflective coating comprises a plurality of layers, the plurality of layers comprising a first low RI layer, a second high RI layer and an optional third layer, wherein at least one of the first low RI layer and the second high RI layer comprises an optical thickness (n*d) in the range from about 2 nm to about 200 nm.

21. The article of claim 18, wherein the article exhibits the reflectance angular color shift at all angles from normal incidence to an incident illumination angle, in the range from about 20 degrees to about 60 degrees.

22. The article of claim 18, wherein the substrate comprises an amorphous substrate or a crystalline substrate.

23. The article of claim 18, further comprising any one or more of an easy-to-clean coating, a diamond-like carbon coating, and a scratch resistant coating, disposed on the anti-reflective coating.

24. An article comprising:

a substrate having a major surface; and

an anti-reflective coating having a thickness of about 1 μ

m or less disposed on the major surface,

wherein the article exhibits an abrasion resistance comprising any one or more of;

about 1% haze or less, as measured using a hazemeter having an aperture, wherein the aperture has a diameter of about 8 mm,

an average roughness, as measured by atomic force microscopy, of about 12 nm RMS or less,

a scattered light intensity of about 0.05 (in units of 1/steradian) or less, at a polar scattering angle of about 40 degrees or less, as measured at normal incidence in transmission using an imaging sphere for scatter measurements, with a 2 mm aperture at 600 nm wavelength, and

a scattered light intensity of about 0.1 (in units of 1/steradian) or less, at a polar scattering angle of about 20 degrees or less, as measured at normal incidence in transmission using an imaging sphere for scatter measurements, with a 2 mm aperture at 600 nm wavelength,

wherein the abrasion resistance is measured after a 500-cycle abrasion using a Taber Test,

wherein the article exhibits an average visible photopic reflectance of about 1% or less over the optical wavelength regime at normal incidence under a D65 or F2 illuminant, and

wherein the article exhibits a b* value, in reflectance, in the range from about −

5 to about 1 as measured on the anti-reflective surface only at all incidence illumination angles in the range from about 0 degrees to about 60 degrees under a D65 illuminant or F2 illuminant.

25. The article of claim 24, wherein anti-reflective coating comprises a plurality of layers, the plurality of layers comprising at least one first low RI layer and more than one second high RI layer, and wherein the combined thickness of the second high RI layers is less than about 500 nm or less.

26. The article of claim 24, wherein the article exhibits a single side average light transmittance of about 98% or greater over the optical wavelength regime.

27. An article comprising:

a substrate having a major surface; and

an anti-reflective coating having a thickness of about 1 μ

m or less disposed on the major surface,

wherein the article exhibits an average visible photopic reflectance of about 0.7% or less over the optical wavelength regime at normal incidence under a D65 or F2 illuminant,

wherein the article exhibits a b* value, in reflectance, in the range from about −

5 to about 1 as measured on the anti-reflective surface only at all incidence illumination angles in the range from about 0 degrees to about 60 degrees under a F2 illuminant, and

wherein the article exhibits a reflectance angular color shift of less than about 5, as measured on the anti-reflective surface at all angles from normal incidence to an incident illumination angle in the range from about 20 degrees to about 60 degrees under a D65 illuminant or F2 illuminant and wherein angular color shift is calculated using the equation √

(a*2−

a*1)2+(b*2−

b*1)2), with a*1, and b*1 representing the coordinates of the article when viewed at normal incidence and a*2, and b*2 representing the coordinates of the article when viewed at the incident illumination angle.

28. The article of claim 27, wherein the article exhibits a maximum hardness of about 8 GPa or greater as measured by a Berkovich Indenter Hardness Test an indentation depth of about 50 nm or greater.

29. The article of claim 27, wherein anti-reflective coating comprises a physical thickness and a plurality of layers comprising a nitride or oxynitride, and wherein the combined physical thickness of the layers comprising a nitride or an oxynitride is 40% or greater of the physical thickness of the anti-reflective coating.

30. The article of claim 27, wherein the angular color shift is less than about 2.