PROCESS FOR DISPENSING A CONTACT LENS FORMING FLUID MATERIAL
A method for dispensing a material into a mold for forming contact lenses, comprises the steps of: (1) providing a contact lens mold, (2) providing a dispensing needle, wherein the dispensing needle is made from a material having a surface energy less than 32 dynes/cm, (3) arranging the contact lens mold underneath the dispensing needle, (4) dispersing a fluid composition into a mold for making a contact lens, wherein the fluid composition comprises a lens-forming material, and the lens-forming material containing a solvent and is crosslinkable and/or polymerizable by thermal curing or actinic radiation.
1 . A method for dispensing a fluid composition comprising volatile solvent into a mold for forming contact lenses, comprises the steps of:
(1) providing a contact lens mold,
(2) providing a dispensing needle, wherein the dispensing needle is made from a material having a surface energy less than 32 dynes/cm,
(3) arranging the contact lens mold underneath the dispensing needle,
(4) dispersing the fluid composition into the contact lens mold, wherein the fluid composition comprises a lens-forming material, wherein the lens-forming material comprising volatile solvent and is crosslinkable and/or polymerizable by thermal curing or actinic radiation, wherein the dispensing needle is free of wicking and dripping after at least 20 more dispensing cycles comparing to the dispensing needle having a same diameter and made from a stainless steel when dispersing the fluid composition at a same set of conditions.
2 . Process according to claim 1 , wherein the dispensing needle is made from a material having a surface energy less than 29 dynes/cm.
3 . Process according to claim 2 , wherein the dispensing needle is made from a material having a surface energy less than 20 dynes/cm.
4 . Process according to claim 3 , wherein the dispensing needle is made from Polytetrafluoroethylene.
5 . Process according to claim 1 , wherein the lens-forming fluid material comprise at least one components selected from the group consisting of a silicone-containing vinylic monomer, a silicone-containing vinylic macromer, a silicone-containing prepolymer, a hydrophilic vinylic monomer, a hydrophobic vinylic monomer, a crosslinking agent (a compound having a molecular weight of about 700 Daltons or less and containing at least two ethylenically unsaturated groups), a free-radical initiator (photoinitiator or thermal initiator), a hydrophilic vinylic macromer/prepolymer, and combination thereof.
6 . Process according to claim 5 , wherein the lens-forming material is lotrafilcon A, lotrafilcon B, senofilcon A, galyfilcon A, balafilcon A, or comfilcon A.
7 . Process according to claim 6 , wherein the solvent is propanol.