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
Estimating the term…
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.
Claims15
A process for the production of an ophthalmic moulding from a material which is polymerisable and/or crosslinkable by impacting with appropriate energy, in a mould which is at least partly permeable to the energy which effects crosslinking, whereby the mould (1) comprising two mould halves, a mother mould half and a father mould half (11), and has a mould cavity which determines the shape of the moulding to be manufactured, wherein the material is introduced into the mould in at least partly uncrosslinked condition and is crosslinked therein by impacting with the energy which effects crosslinking to an extent that is sufficient to make the lens removable from the mould, characterised in that at least one of the two mould halves comprising a polymer whose oxygen permeability is less than:
- 4 5 10 - 11 ( ml O 2 at STP ) ( mm ) ( cm 2 ) ( s ) ( torr )
- which process comprising the step of crosslinking said polymerisation material.
A device for the production of optical lenses with a closable and openable mould comprsing two mould halves, a mother mould half and a father mould half, the mould having a mould cavity which determines the shape of the lens to be manufactured, whereby the mould is designed to receive a crosslinkable material and is at least partly permeable to externally introduced energy which effects crosslinking of the material, and with a source for the energy which effects crosslinking, as well as with means to impact the mould with the energy which effects crosslinking, characterised in that at least one of the two mould halves comprising a polymer, whose oxygen permeability is less than:
- 5 5 × 10 - 11 ( ml O 2 at STP ) ( mm ) ( cm 2 ) ( s ) ( torr )
Dependencies are inferred from the claim text.