Reusable castings molds
View Patent ↗The invention is directed to a reusable mold for making a contact lens and the reusable mold has at least one of the mold halves is made from an oxide glass having a Knoop Hardness less than HK 350. The invention is also directed to a method for making an optical part by single point diamond turning an oxide glass having a Knoop Hardness HK less than 350.
1. A reusable mold for making a contact lens, comprising a first reusable mold half having a first mold surface in contact with a lens forming composition and a second reusable mold half having a second mold surface in contact with the lens forming composition, wherein the first reusable mold half and the second reusable mold half are configured to receive each other such that a cavity is formed between the first reusable mold surface and the second reusable mold surface, wherein the cavity defines the shape of a contact lens to be molded, wherein the lens forming composition is polymerizable and/or crosslinkable by an actinic radiation, wherein at least one of the reusable mold halves is made from an oxide glass having a Knoop Hardness (HK) less than 350.
2. The reusable mold of claim 1 , wherein the Knoop Hardness is less than 340.
3. The reusable mold of claim 2 wherein the Knoop Hardness is less than 320.
4. The reusable mold of claim 1 , wherein the reusable mold has a surface roughness (Ra) less than 30 nm.
5. The reusable mold of claim 4 , wherein the reusable mold has a surface roughness (Ra) less than 10 nm.
6. The reusable mold of claim 1 , wherein the oxide glass is substantially free of silicon oxide.
7. The reusable mold of claim 6 , wherein the oxide glass comprises 1% to 60% phosphorous oxide.
8. The reusable mold of claim 7 , wherein the oxide glass further comprises 20% to 30% fluorine.