Anti-soiling coating for an ophthalmic lens
A hydrophobic and/or oleophobic coating system for an ophthalmic lens having increased effective thickness and water contact angle. In one embodiment, the hydrophobic and/or oleophobic coating system comprises an anti-reflective coating applied to an ophthalmic lens, the anti-reflective coating comprising alternating layers of high and low index materials with an outer layer of silicon dioxide having exposed hydroxyl groups. A hydrophobic coating is applied to the anti-reflective coating, the hydrophobic coating comprising a silane with a hydrophobic group and fewer than three reactive groups capable of bonding to the exposed hydroxyl groups of the anti-reflective coating.
1. An anti-soiling coating system for an ophthalmic lens, comprising:
an optical lens;
a first coating applied to the lens, comprising an outer layer of silicon dioxide having exposed hydroxyl groups; and
a hydrophobic second coating applied to the outer layer of the first coating;
wherein
the hydrophobic second coating comprises a silane having a fluorinated hydrocarbon group and three functional groups reactive to the exposed hydroxyl groups of the first coating,
wherein 1 or 2 of the 3 functional groups are reactive to form a bond with the exposed hydroxyl groups of the first coating and the remainder of the functional groups are less reactive.
2. The anti-soiling coating system of claim 1 , wherein the first coating is an anti-reflective coating comprising alternating layers of high and low index materials.
3. The anti-soiling coating system of claim 2 , wherein the layers of high index materials are selected from the group consisting of: TiO 2 , ZrO 2 and HfO 2 , and the layers of low index materials are selected from the group consisting of: SiO 2 , MgF 2 , and Al 2 O 3 .
4. The anti-soiling coating system of claim 1 , wherein the functional groups reactive to form a bond are methoxy groups.
5. The anti-soiling coating system of claim 4 , wherein the less reactive functional group is an ethoxy group.
6. The anti-soiling coating system of claim 1 , wherein the hydrophobic second coating has a water contact angle greater than 113°.
7. The anti-soiling coating system of claim 1 , wherein the hydrophobic second coating has a water contact angle between 113° to 114°.
8. The anti-soiling coating system of claim 1 , wherein the hydrophobic second coating has a water contact angle between 115° to 117°.
9. The anti-soiling coating system of claim 1 , wherein the hydrophobic second coating forms a layer with a maximum effective thickness greater than 20 nm.
10. The anti-soiling coating system of claim 1 , wherein the hydrophobic second coating forms a layer with a maximum effective thickness that is at least about 30 nm.
11. The anti-soiling coating system of claim 1 , wherein the hydrophobic second coating forms a layer with a maximum effective thickness that is at least about 40 nm.