Process for producing surface-treated glass plate

1. A process for producing a surface-treated glass plate having a plurality of concave portions on a surface of a glass plate, the method comprising:

providing a glass plate having a strain point;

heating the glass plate in a range from the strain point (°C.) to the strain point +250 (°C.);

exposing the heated glass plate to an atmosphere containing water in a concentration of 0.01 to 20 g/L so as to form a hydrated layer only on a surface of the heated glass plate to generate a phase separation which separates to a high SiO 2 phase and a high alkaline-containing phase in the hydrated layer:

wherein exposing the heated glass plate to the atmosphere generates phase separation from the surface to 1 μm or less of the heated glass plate;

wherein the temperature of the glass plate when exposing the heated glass plate to the atmosphere is from the strain point of the glass to the strain point +250° C.; and

washing the glass plate to remove the high alkaline- containing phase;

wherein the plurality of concave portions having a range of average open pore diameter/depth of 10/100 to less than 1000/50 are formed on the surface of the glass plate after washing the glass plate.

2. The process for producing a surface-treated glass plate according to claim 1 , wherein washing the glass plate includes removing the high alkaline-containing phase by dissolving it in water.

3. The process for producing a surface-treated glass plate according to claim 1 , wherein the exposure time for exposing the heated glass plate to the atmosphere is 1 to 30 minutes.

4. The process for producing a surface-treated glass plate according to claim 1 , wherein the temperature of the heated glass plate is from 510 to 760° C.

5. The process for producing a surface-treated glass plate according to claim 1 , wherein the glass plate contains an alkali component in a range of 1 to 30 mass % in terms of an oxide.

6. The process for producing a surface-treated glass plate according to claim 1 , wherein the atmosphere to which the heated glass plate is exposed further contains SO 2 and/or NO 2 .

7. The process for producing a surface-treated glass plate according to claim 1 , wherein the SO 2 and/or NO 2 is added in a concentration sufficient to accelerate the hydration of the glass surface but not more than 100 ppm.

8. The process for producing a surface-treated glass plate according to claim 1 , wherein exposing the heated glass plate to the atmosphere is performed during slow cooling after forming the glass plate on a glass plate production line.

9. The process for producing a surface-treated glass plate according to claim 1 , wherein the plurality of concave portions having an average open pore diameter of 10 nm to less than 1 μm are formed on the surface of the glass plate after washing the glass plate, and a plane of the surface of the glass plate, excluding a region in which the plurality of concave portions are formed, is a flat plane.

10. The process for producing a surface-treated glass plate according to claim 1 , wherein an area ratio of an open pore area of the plurality of concave portions to the unit area of the surface of the glass plate is from 5 to 80%, and an average pitch between respective concave portions is 1 μm or less in a cross-sectional view of the plurality of concave portions.

11. The process for producing a surface-treated glass plate according to claim 1 , wherein the temperature of the heated glass plate is from 600 to 760° C.