초록 ▼

A polyolefin mould for casting contact lenses from a polymerizable monomer composition which shrinks on polymerization, said mould comprising: male (50) and female (51) mould halves at least one of which has a flexible diaphragm portion (53, 54) which is shaped to provide a surface corresponding to

A polyolefin mould for casting contact lenses from a polymerizable monomer composition which shrinks on polymerization, said mould comprising: male (50) and female (51) mould halves at least one of which has a flexible diaphragm portion (53, 54) which is shaped to provide a surface corresponding to a lenticular surface, said mould halves (50, 51), when closed together, cooperating to define a mould cavity (52) for receiving a volume of said monomer composition, at least one of said mould halves (50, 51) having a shoulder portion (55, 56) 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 (53, 54) is deflected into said cavity under forces exerted on said mould by said monomer composition when polymerized in said closed cavity (52), thereby compensating for the shrinkage occurring on polymerization 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.

대표청구항 ▼

A polyolefin mould for casting contact lenses from a polymerisable monomer composition which shrinks on polymerisation, said mould comprising (a) male and female mould halves each of which has a diaphragm portion which is shaped to provide a surface corresponding to a lenticular surface, said mould

A polyolefin mould for casting contact lenses from a polymerisable monomer composition which shrinks on polymerisation, said mould comprising (a) male and female mould halves each of which has a 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, (b) each of said mould halves having a non-flexible shoulder portion surrounding said cavity and shaped so that on closing the mould under a closing pressure said shoulder portions engage in an essentially line contact to form a liquid-tight seal of the cavity and to define an edge moulding portion of said cavity; and (c) the diaphragm portion of the male mould being more flexible than the female, whereby in use, the male diaphragm portion is deflected into said cavity under the forces generated in said mould by said monomer composition when polymerised in said closed cavity.