Method of making a wipe-resistant antireflection coating on a borosilicate glass body and coating solution for use in said method
In the method of making an adherent and wipe-resistant porous SiO 2 -containing antireflection coating on a borosilicate glass body a coating solution containing from 1.0 to 6.0 wt. % of HCl, from 0.5 to 7.0 wt. % of a SiO 2 sol based on solids content, from 0.5 to 5.0 wt. % of water, and from 85 to 98 wt. % of at least one volatile water-soluble organic solvent, is used to form an antireflection coating on the glass body. A glass body, on which the foregoing coating can be provided with good adherence and wipe resistance properties, is made of borosilicate glass having a composition, in percent by weight based on oxide content, of SiO 2 , 70 to 75; B 2 O 3 , 8 to 11; Al 2 O 3 , 5 to 9; alkali metal oxides, 7 to 12; and alkaline earth metal oxides, 0 to 10.
1. A method of making adherent and wipe-resistant porous SiO 2 -containing antireflection coatings on borosilicate glass bodies, said method comprising the steps of:
a) providing a borosilicate glass body to be coated, said borosilicate glass body with a composition, in percent by weight based on oxide content, consisting of SiO 2 , 70 to 75; B 2 O 3 , 8 to 11; Al 2 O 3 , 5 to 9; alkali metal oxides, 7 to 12; and alkaline earth metal oxides, 0 to 10;
b) wetting said borosilicate glass body to be coated with a coating solution consisting of from 1.0 to 6.0 wt. % of HCl, from 0.5 to 7.0 wt. % of a SiO 2 sol based on solids content, from 0.5 to 5.0 wt. % of water, and from 85 to 98 wt. % of at least one volatile water-soluble organic solvent, to form an antireflection coating on the borosilicate glass body; and then
c) drying and burning in the antireflection coating formed on the borosilicate glass body in step b) at a temperature of about 450° C. to 35° C. above a glass transformation temperature Tg of the glass body.
2. The method as defined in claim 1 , in which said at least one volatile water-soluble organic solvent is selected from the group consisting of methanol, ethanol, propanols, butanols, dimethylketone and methylethylketone.
3. The method as defined in claim 1 , in which the wetting of the glass body to be coated occurs by dipping the glass body to be coated in the coating solution.
4. The method as defined in claim 3 , further comprising removing the glass body from the coating solution with a withdrawal speed between 1 mm·s −1 and 100 mm·s −1 .
5. The method as defined in claim 4 , wherein said withdrawal speed is between 1 mm·s −1 and 20 mm·s −1 .
6. The method as defined in claim 1 , wherein said borosilicate glass body with a composition consisting of from 70 to 75 wt. % of said SiO 2 , from 8 to 11 wt. % of said B 2 O 3 ; from 6 to 8 wt. % of said Al 2 O 3 ; from 6 to 8 wt. % of Na 2 O; from 1 to 4 wt. % of K 2 O; and from 0 to 2 wt. % of CaO.