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US 6,821,108 B2Granted
Plastic castings molds
AssigneeNovartis AG
InventorsPeter Hagmann, Axel Heinrich, Willi Hoerner, Robert Allen Janssen, John Martin Lally, Robert Earl Szokolay, Bernhard Seiferling
Life of this patent
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Abstract
The invention is concerned with the problem that with known plastic casting moulds, especially those of polypropylene, the lenses produced with these moulds have a slippery surface. The invention solves this problem through the use of polymers which are notable for their very low oxygen permeability.
Claims20
A device for the production of ophthalmic lenses, comprising:
- a closable and openable mould having a cavity capable of receiving a lens material which is polymerisable and/or crosslinkable upon irradiation with UV light having a wavelength of greater than 280 nm and is in at least partly uncrosslinked condition;
- and
- an at least partly opaque mask which provides a spatial limitation of UV irradiation to crosslink or polymerize the lens material so as to produce an ophthalmic lens having a first surface, an opposite second surface, and an edge,
- wherein the mould includes a first mold half defining a first optical surface and a second mold half defining a second optical surface, wherein said first mold half and said second mold half are configured to receive each other such that the cavity is formed between said first optical surface and said second optical surface, wherein the first mold half is transparent to the UV light, wherein the second mold half is made from a polymer and contains UV absorbers which adsorb the UV light to an extent so that the UV light is not substantially reflected by the second mold half, wherein said polymer has an oxygen permeability less than 5 × 10 - 11 ( ml O 2 at STP ) ( mm ) ( cm 2 ) ( s ) ( torr )
- wherein the first surface of the lens is defined by the first optical surface, the second surface of the lens is defined by the second optical surface, and the geometry of the edge is defined by the spatial limitation of UV irradiation.
2 more elements
A contact lens produced by a process which comprises the step of:
- (1) introducing a lens material into a cavity formed by a mould, wherein the material is polymerisable and/or crosslinkable upon irradiation with UV light having a wavelength of greater than 280 nm and is in at least partly uncrosslinked condition, wherein the mould has a first mold half defining a first optical surface and an UV-absorbable second mold half defining a second optical surface, wherein said first mold half and said UV-absorbable second mold half are configured to receive each other such that the cavity is formed between said first optical surface and said second optical surface, wherein the first mold half is transparent to the UV light, wherein the UV-absorbable second mold half comprises a polymer whose oxygen permeability is less than 5 × 10 - 11 ( ml O 2 at STP ) ( mm ) ( cm 2 ) ( s ) ( torr ) ,
- and wherein the UV-absorbable second mold half can substantially reduce the reflection of the UV light by the UV-absorbable second mold half;
- and
- (2) crosslinking the lens material under a spatial limitation of UV irradiation to form the ophthalmic moulding having a first surface, an opposite second surface, and an edge, wherein the spatial limitation of UV irradiation is provided by a mask, wherein the first surface is defined by the first optical surface, the second surface is defined by the second optical surface, and the geometry of the edge is defined by the spatial limitation of UV irradiation, and wherein the use of the UV-absorbable second mold half reduces substantially the crosslinking, induced by reflected UV light, of lens material around the actual edge so that the quality of the edge is improved.
1 more element
Dependencies are inferred from the claim text.