Low-reflection glass article

• US 6,921,578 B2
• Filed: 08/11/2001
• Issued: 07/26/2005
• Est. Priority Date: 12/13/1999
• Status: Expired due to Term

• Current Assignee: Nippon Sheet Glass Company Limited
• Original Assignee: Nippon Sheet Glass Company Limited
• Inventors: Okamoto, Hideki, Tsujino, Toshifumi, Kawahara, Tetsuro
• Primary Examiner(s): McNeil, Jennifer
• Assistant Examiner(s): Blackwell-Rudasill, G.
• Application Number:
  US09/928,836
• Publication Number:
  US 20020014090A1
• Time in Patent Office: 1,445 Days
• Field of Search: 428/428, 428/429, 428/432, 428/402, 428/403, 428/404, 428/446, 428/323, 428/331, 428/332, 136/252, 136/256, 136/257, 136/261, 1062861-286, 106/287.34, 501/12, 501/133, 501/128
• US Class Current: 428/428
• CPC Class Codes: C03C 1/008 for the production of films or coatings
• CPC Class Codes: C03C 17/007 containing a dispersed phase, e.g. particles, fibres or flakes, in a continuous phase
• CPC Class Codes: C03C 17/42 at least one coating of an organic material and at least one non-metal coating
• CPC Class Codes: C03C 19/00 Surface treatment of glass, not in the form of fibres or filaments, by mechanical means sand-blasting, grinding, or polishing glass B24
• CPC Class Codes: C03C 2217/213 SiO2
• CPC Class Codes: C03C 2217/42 consisting of particles only
• CPC Class Codes: C03C 2217/478 Silica
• CPC Class Codes: C03C 2218/113 by sol-gel processes
• CPC Class Codes: C03C 2218/116 by spin-coating, centrifugation
• CPC Class Codes: F24S 80/52 characterised by the material for preventing heat loss F24S80/56
• CPC Class Codes: G02B 1/11 Anti-reflection coatings
• CPC Class Codes: G02B 1/12 by surface treatment, e.g. by irradiation
• CPC Class Codes: H01L 31/02168 the coatings being antireflective or having enhancing optical properties for the solar cells
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/2993 Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]

Abstract

A low reflection film comprising silica fine particles and a binder in a weight ratio proportion of 60:40 to 95:5 is obtained by mixing starting fine particles comprising at least non-aggregated silica fine particles with a mean particle size of 40-1000 nm and/or linear (chain-like) aggregated silica fine particles with a mean primary particle size of 10-100 nm, a hydrolyzable metal compound, water, and a solvent, hydrolyzing the hydrolyzable metal compound in the presence of the starting fine particles, and then coating the prepared coating solution onto a glass base substrate and subjecting it to heat treatment.

The obtained low reflection film is a single-layer low reflection film with low reflectivity, excellent abrasion resistance, high film strength and excellent contamination removal property, and coating of the low reflection film onto glass base substrates can give low reflection glass articles.

Claims

1. A low reflection glass article obtained by forming a low reflection film composed of silica fine particles and a binder composed of metal compounds on a glass base substrate, the low reflection glass article being characterized in that said low reflection film contains said silica fine particles and said binder in a weight ratio proportion of 60:

40 to 95;

5, and in that said low reflection film is formed by coating a coating solution onto the glass base substrate and subjecting it to heat treatment, said coating solution being prepared by adding a hydrolyzable metal compound (1) in a state before hydrolyzation, to a mixture of starting fine particles (2) comprising non-aggregated silica fine particles with a mean particle size of 40-1000 nm and/or linear (chain-like) aggregated silica fine particles with a mean primary particle size or 10-100 nm, water (3), and a solvent (4),

and then hydrolyzing the hydrolyzable metal compound in the presence of an acid catalyst, the acid catalyst being added before or after the addition of the hydrolyzable metal compound to the starting fine particles, and

the coating solution undergoing a condensation reaction between a product of the hydrolysis and a silanol present on said silica fine particles, such that the binder covers surfaces of the silica fine particles, enhancing an adhesion between the silica fine particles.

2. A low reflection glass article according to claim 1, wherein said hydrolyzable metal compound is at least one type of metal alkoxide selected from the group consisting of silicon alkoxides, aluminum alkoxides, titanium alkoxides, zirconium alkoxides and tantalum alkoxides, and said binder is the oxide of the metal of said metal compound.

3. A low reflection glass article according to claim 1 or 2, wherein said low reflection film contains the silica fine particles and the binder in a proportion of 65:

35 to 85;

15 by weight.

4. A low reflection glass article according to claim 1, wherein the non-aggregated silica fine particles in said coating solution have a long axis length to short axis length ratio of 1.0-1.2.

5. A low reflection glass article according to claim 1, wherein the non-aggregated silica fine particles in said coating solution have a primary particle size standard deviation of 1.0-1.5.

6. A low reflection glass article according to claim 1, wherein said starting fine particles consist only of said non-aggregated silica fine particles with a mean particle size of 40-500 nm.

7. A low reflection glass article according to claim 1, wherein said starting fine particles consist only of said non-aggregated silica fine particles with a mean particle size of 100-1000 nm.

8. A low reflection glass article according to claim 1, wherein said starting fine particles consist only of said non-aggregated silica fine particles, and said non-aggregated silica fine particles comprise

(1) 70-95 wt % of a first type of non-aggregated silica fine particles with a mean particle size of 40-200 nm and

(2) 5-30 wt % of a second type of non-aggregated silica fine particles with a mean particle size of from more than 200 nm to 3000 nm or less and at least 100 nm larger than the mean particle size of tile first type of non-aggregated silica fine particles.

9. A low reflection glass article according to claim 6, wherein said low reflection film has 30-3000 fine particles present in a 1 μ

m×

1 μ

m square area of the surface of the film as seen from above the film, and the fine particles have a mean particle size of 40-500 nm.

10. A low reflection glass article according to claim 7, wherein said low reflection film has 10-50,000 fine particles present in a 10 μ

m×

10 μ

m square area of the surface of the film as seen from above the film, and the fine particles have a mean particle size of 100-1000 nm.

11. A low reflection glass article according to claim 6 or 7, wherein said low reflection film has 5,000,000/D² to 10,000,000/D² fine particles with a mean particle size Dnm of 40-1000 nm present in a 10 μ

m×

10 μ

m square area of the surface of the film as seen from above the film.

12. A low reflection glass article according to claim 1, wherein said low reflection film has only one fine particle or 2-5 stacked fine particles in the direction of film thickness as seen from a cross-section taken in the direction of the thickness.

13. A low reflection glass article according to claim 8, wherein said low reflection film has 50% or less of its surface area occupied by fine particles from said second non-aggregated silica fine particles, as seen from above the film.

14. A low reflection glass article according to claim 1, wherein said binder coats the entire surface of said silica fine particles to a thickness of 1-100 nm and 2-9% of the mean particle, size of said silica fine particles.

15. A low reflection glass article according to claim 1, wherein said low reflection film has an average thickness of from 90 nm to 350 nm.

16. A low reflection glass article according to claim 1, wherein said low reflection film has an average thickness of from 90 nm to 180 nm.

17. A low reflection glass article according to claim 1, wherein said heat treatment is carried out so that the maximum temperature reached by the glass base substrate coated with said coating solution is 200°

C. or higher.

18. A low reflection glass article according to claim 1, wherein said low reflection film has a surface roughness (Ra) of 3-50 nm as measured with an AFM (atomic force microscope).

19. A low reflection glass article according to claim 1, wherein said glass base substrate is a sheet, and said reflection film has reflectivity of 2% or less for incident light from the low reflection film side of the sheet glass base substrate at an incident angle of 12°

with respect to standard light A specified by JIS-Z8720, as the reflectivity including no reflection from the back side of the sheet glass base substrate.

20. A low reflection glass article according to claim 1, wherein said glass base substrate is a sheet, and said low reflection glass article has a haze value of 30% or less.

21. A low reflection glass article according to claim 1, wherein said glass base substrate is a sheet, and said low reflection glass article has a haze value of 1% or less.

22. A low reflection glass article according to claim 1, wherein said glass base substrate is a sheet, and said low reflection glass article has a total light transmittance equivalent to or higher man the total light transmittance of said glass base substrate, and a haze value of 10-90%.

23. A low reflection glass article according to claim 1, wherein said low reflection glass article is an automobile window.

24. A low reflection glass article according to claim 1, wherein said low reflection glass article is a building window, show window, display glass sheet or optical glass member.

25. A low reflection glass article according to claim 1, wherein said low reflection glass article is a solar cell glass sheet or solar water heater glass sheet.

26. A low reflection glass article for a solar cell or solar water heater, wherein a low reflection film comprising silica fine particles and a binder composed of metal compounds is formed on a float glass substrate with a total light transmittance of 85% or greater and a composition of soda lime silicate glass,

the low reflection glass article being characterized in that said low reflection film contains said silica fine particles and said binder in a proportion of 65:

35 to 95;

5 by weight, said binder being coated onto said silica fine particles to a thickness of 1-100 nm after undergoing hydrolyzatlon in the presence of the silica fine particles, and undergoing a condensation reaction between a product of the hydrolysis and a silanol present on the silica fine particles, and has a total light transmittance equivalent to or higher than the total light transmittance of said glass substrate.