Method for making silicone hydrogel contact lenses

A method for making contact lenses, comprising the steps of:

• (1) obtaining a fluid polymerizable composition,
• wherein the polymerizable materials comprises (a) at least one siloxane-containing (meth)acrylamido monomer, (b) at least one polysiloxane vinylic crosslinker, wherein all ethyleneically unsaturated groups of said at least one polysiloxane vinylic crosslinker are (meth)acrylamido groups, (meth)acryloxy groups, vinyloxycarbonyl-amino groups, vinyloxy-carbonyloxy groups, or combinations thereof, (c) from about 15% to about 55% by weight of at least one hydrophilic (meth)acrylamido monomer having 3 to 8 carbon atoms, (d) from about 4% to about 20% by weight of an organic solvent having 3 to 8 carbon atoms relative to the total weight of the polymerizable composition, (e) at least one thermal free radical initiator having a 10-hour half-life temperature (designated as “T10hλ”) of from about 50° C. to about 90° C., wherein the sum of the amounts of components (a) to (c) is at least 90% by weight relative to total amount of all polymerizable components in the polymerizable composition;
• (2) introducing the polymerizable composition into lens molds, wherein each lens mold comprises a male mold half having a first molding surface and a female mold half having a second molding surface, wherein the male and female mold halves are configured to receive each other such that a mold cavity is formed between the first and second molding surfaces when each lens mold is closed;
• (3) curing thermally the polymerizable composition in the lens molds in an oven according to a curing profile to form silicone hydrogel lens precursors, wherein the curing profile comprises or consists essentially of increasing the oven's temperature from a first temperature, T1, to a second temperature, T2, at a ramping rate, rT, and then lowering the oven's temperature from T2 to T1 or lower, wherein
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• (° C./minute) in which t is a total curing time of from about 30 minutes to about 200 minutes;
• (4) separating each lens molds into male and female mold halves, with one silicone hydrogel lens precursor being adhered on one lens-adhered mold half which is one of the male and female mold halves of each lens mold;
• (5) removing silicone hydrogel lens precursors from lens-adhered mold halves;
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• (6) subjecting the silicone hydrogel lens precursors to one or more post-molding processes selected from the group consisting of extraction, surface treatment, hydration, packaging, sterilization, and combinations thereof, to form silicone hydrogel contact lenses.