B - Operations – Transporting – 29 – D
Patent
B - Operations, Transporting
29
D
18/106
B29D 11/00 (2006.01) A45C 11/00 (2006.01) B29C 33/00 (2006.01) B29C 33/44 (2006.01) B29C 37/00 (2006.01)
Patent
CA 1316649
ABSTRACT 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 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.
528427
Henderson Peter
Seden William Edward
Shepherd David William James
Coopervision Inc.
Mccarthy Tetrault Llp
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