Method of manufacturing wettable silicone hydrogel contact lenses
View Patent ↗A method for manufacturing a silicone hydrogel contact lens is described that comprises curing a polymerizable composition comprising at least one siloxane monomer and at least one hydrophilic vinyl-containing monomer in a contact lens mold comprising a molding surface having a coating comprising a hydrophilic polymer. The hydrophilic coating is not solubilized by the polymerizable composition during the curing step. The resulting polymeric lens body is removed from the mold, washed to remove any of the hydrophilic polymer that may have transferred from the mold surface to the lens during the curing or lens removal process, and packaged to provide a silicone hydrogel contact lens having a contact angle that is lower than what it would otherwise be had the lens been cured in the same contact lens mold lacking the hydrophilic coating.
1. A method of manufacturing a silicone hydrogel contact lens, said method comprising:
a. curing a polymerizable composition comprising at least one siloxane monomer and at least one hydrophilic vinyl-containing monomer in a contact lens mold to form a polymeric lens body; and
b. washing and packaging the polymeric lens body to provide a silicone hydrogel contact lens having a first contact angle;
wherein said contact lens mold comprises a molding surface coated with a hydrophilic coating comprising at least one hydrophilic polymer,
wherein the hydrophilic coating is not solubilized by the polymerizable composition during the curing step, and
the silicone hydrogel contact lens is substantially free of the hydrophilic polymer from the hydrophilic coating, and
the first contact angle is lower than a second contact angle of a control silicone hydrogel contact lens cured in an uncoated, but otherwise identical, contact lens mold and manufactured using a method that is identical to the method of manufacturing the silicone hydrogel contact lens, and wherein the hydrophilic polymer is free of primary amine groups and has an average molecular weight of about 10,000 daltons to about 200,000 daltons.
2. The method of claim 1 , wherein the contact lens mold comprises a non-polar material.
3. The method of claim 2 , wherein the contact lens mold comprises polypropylene.
4. The method of claim 1 , wherein prior to the curing step, the hydrophilic coating is applied to the contact lens mold by a process that comprises spin-coating or spray-coating.
5. The method of claim 1 , wherein the coating has an average thickness of about 0.01 μm to about 10 μm.
6. The method of claim 1 , wherein the hydrophilic polymer has said average molecular weight of about 10,000 daltons to about 125,000 daltons.
7. The method of claim 1 , wherein the coating comprises polyvinyl alcohol (PVOH).
8. The method of claim 1 , wherein the molding surface is pre-treated by air plasma, UV-ozone, or corona discharge prior to being coated with the hydrophilic coating.
9. The method of claim 1 , wherein the polymerizable composition comprises a total amount of siloxane monomer of about 20 wt. % to about 60 wt. % based on the total weight of all polymerizable ingredients in the polymerizable composition.
10. The method of claim 1 , wherein the polymerizable composition comprises a total amount of hydrophilic vinyl-containing monomer of about 20 wt. % to about 60 wt. % based on the total weight of all polymerizable ingredients in the polymerizable composition.
11. The method of claim 1 , wherein the hydrophilic vinyl-containing monomer is N-vinyl-N-methylacetamide (VMA), or N-vinyl pyrrolidone (NVP), or a combination of both VMA and NVP.
12. The method of claim 1 , wherein the polymerizable composition further comprises an acrylate-containing hydrophilic monomer in an amount up to 20 wt. % based on the total weight of all polymerizable ingredients in the polymerizable composition.
13. The method of claim 1 , wherein the polymerizable composition further comprise at least one acrylate-containing hydrophilic monomer, and the polymerizable composition has a ratio of total amount of hydrophilic vinyl-containing monomer to total amount of acrylate-containing hydrophilic monomer of at least 2:1.
14. The method of claim 1 , wherein the polymerizable composition comprises no more than 1 wt. % of an acrylate-containing monomer comprising a carboxylic acid group based on the total weight of all polymerizable ingredients in the polymerizable composition.
15. The method of claim 1 , wherein the polymerizable composition is in the absence of an acrylate-containing hydrophilic monomer.
16. The method of claim 1 , wherein the polymerizable composition is diluent-free.
17. The method of claim 1 , wherein the silicone hydrogel contact lens is washed in the absence of liquids comprising volatile organic solvents.
18. The method of claim 1 , wherein the first contact angle is less than 50°.
19. The method of claim 1 , wherein the first contact angle is at least 30% lower than the second contact angle.
20. The method of claim 1 , wherein the curing step comprises exposing the polymerizable composition to polymerizing amounts of ultraviolet (UV) light.
21. The method of claim 1 , wherein prior to the washing step, the polymeric lens body is dry-delensed from the mold.
22. The method of claim 1 , wherein the silicone hydrogel contact lens is manufactured in the absence of a post-polymerization surface modification to impart wettability to the contact lens.
23. The method of claim 1 , wherein the hydrophilic polymer from the hydrophilic coating is not the same as any hydrophilic polymer in the polymerizable composition and/or formed by curing the polymerizable composition during the curing step.