MOULDING CONTACT LENSES

The invention relates to a polyolefin mould for casting contact lenses from a polymerisable monomer composition which shrinks on polymerisation, said mould comprising: male and female mould halves at least one of which has a flexible diaphragm portion which is shaped to provide a surface correspondi...

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Bibliographische Detailangaben
Hauptverfasser:	SHEPHERD, DAVID W. J, SEDEN, WILLIAM E, HENDERSON, PETER
Format:	Patent
Sprache:	eng ; fre
Schlagworte:	ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING CHEMISTRY CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS,e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES,DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS CONVEYING HAND CARRIED BAGS HAND OR TRAVELLING ARTICLES HANDLING THIN OR FILAMENTARY MATERIAL HETEROCYCLIC COMPOUNDS HUMAN NECESSITIES HYGIENE INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULARARTICLES INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS LAYERED PRODUCTS LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT ORNON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM LUGGAGE MEDICAL OR VETERINARY SCIENCE METALLURGY ORGANIC CHEMISTRY PACKAGES PACKAGING ELEMENTS PACKING PERFORMING OPERATIONS PREPARATIONS FOR MEDICAL, DENTAL, OR TOILET PURPOSES PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCESIN A PLASTIC STATE PURSES SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR SHAPING OR JOINING OF PLASTICS SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS ORMEDICINAL PREPARATIONS STORING TRANSPORTING WORKING OF PLASTICS WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL
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Beschreibung
Zusammenfassung:	The invention relates to a polyolefin mould for casting contact lenses from a polymerisable monomer composition which shrinks on polymerisation, said mould comprising: male and female mould halves at least one of which has a flexible diaphragm portion which is shaped to provide a surface corresponding to a lenticular surface, said mould halves, when closed together, cooperating to define a mould cavity for receiving a volume of said monomer composition, at least one of said mould halves having a shoulder portion surrounding said cavity and shaped to engage with said other mould half to define an edge moulding portion of said cavity, whereby in use said diaphragm is deflected into said cavity under forces exerted on said mould by said monomer composition when polymerised in said closed cavity, thereby compensating for the shrinkage occuring on polymerisation and avoiding the formation of bubbles or voids in the resulting lenses. In addition, the invention includes a method of casting contact lenses using a mould of the above kind.