Lens manufacturing process
First Claim
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1. A method for molding an ophthalmic lens comprising:
- (a) providing a first mold part having a front curve molding surface for the ophthalmic lens;
(b) providing a second mold part having a back curve molding surface for the ophthalmic lens;
(c) extruding a melt-processable polymer;
(d) cutting a sample from the extruded polymer;
(e) depositing the sample in the first mold part;
(f) moving the first and the second mold parts together to form a mold cavity between the opposing front curve molding surface and back curve molding surface with the polymer therebetween, the mold cavity defining a shape of an ophthalmic lens having a variable volume between a first volume and a second volume, the second volume being greater than the first volume, wherein the mold parts have sufficiently small clearance such that gas escapes from the mold cavity and none of the polymer escapes from the mold cavity;
(g) squeezing the mold parts together with a predetermined force; and
(h) allowing the polymer to solidify and form a lens.
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Abstract
A process for manufacturing ophthalmic lenses is described. This process has several phases, including raw material processing, material metering and dispensing, the material shaping, and ejection/de-molding. The material-shaping phase can utilize various molding processes including compression molding, thermoforming, reaction injection molding, or injection molding. The process allows re-use of the shaping molds/dies and can be automated.
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Citations
47 Claims
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1. A method for molding an ophthalmic lens comprising:
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(a) providing a first mold part having a front curve molding surface for the ophthalmic lens;
(b) providing a second mold part having a back curve molding surface for the ophthalmic lens;
(c) extruding a melt-processable polymer;
(d) cutting a sample from the extruded polymer;
(e) depositing the sample in the first mold part;
(f) moving the first and the second mold parts together to form a mold cavity between the opposing front curve molding surface and back curve molding surface with the polymer therebetween, the mold cavity defining a shape of an ophthalmic lens having a variable volume between a first volume and a second volume, the second volume being greater than the first volume, wherein the mold parts have sufficiently small clearance such that gas escapes from the mold cavity and none of the polymer escapes from the mold cavity;
(g) squeezing the mold parts together with a predetermined force; and
(h) allowing the polymer to solidify and form a lens. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 36, 37, 39)
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35. A method for molding an ophthalmic lens comprising:
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(a) providing an ophthalmic lens mold cavity;
(b) depositing an amount of a melt-processable polymer into the open mold cavity;
(c) closing the mold cavity with sufficient force so as to deform the polymer therein into an ophthalmic lens;
(d) opening the mold cavity; and
(e) removing the ophthalmic lens.
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38. A method for molding an ophthalmic lens comprising:
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(a) providing an ophthalmic lens mold cavity;
(b) depositing an amount of a reactive pre-polymer into the open mold cavity;
(c) maintaining the temperature of the mold cavity greater than 120°
C. below the Tg of the pre-polymer deposited therein;
(d) closing the mold cavity so as to force out gas and shape the pre-polymer therein into an ophthalmic lens;
(e) maintaining the mold cavity in a closed position for a period less than 500 seconds sufficient to allow the pre-polymer to sufficiently react into a polymer that retains the shape of the mold cavity to form an ophthalmic lens;
(f) opening the mold cavity; and
(g) removing the ophthalmic lens.
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40. A method for molding an ophthalmic lens comprising:
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(a) providing a first mold part having a front curve molding surface for the ophthalmic lens;
(b) providing a second mold part having a back curve molding surface for the ophthalmic lens, the mold halves adapted to mate together to form a mold cavity in the shape of an ophthalmic lens having a variable volume at least between a first volume and a second volume, the second volume being greater than the first volume;
(c) providing a first reactive fluid component at a first temperature;
(d) providing a second reactive fluid component at a second temperature, said reactive components capable of forming a hydrophilic polymer;
(e) mixing the first and second feed components together at a third temperature capable of initiating a reaction between the components and for a residence time sufficient to convert the fluid components into a fluid pre-polymer material;
(f) dispensing a sample of the pre-polymer material into the first mold part, the sample having a volume between the first volume and the second volume, the first mold part having a fourth temperature;
(g) moving the mold parts together to form a mold cavity such that the back curve molding surface contacts the pre-polymer material, the back curve molding surface having a fifth temperature;
(h) squeezing the mold parts together with a predetermined force, wherein the mold parts have sufficiently small clearance such that gas escapes from the mold cavity, and none of the sample escapes from the mold cavity;
(i) maintaining the predetermined force on the moldable material for a period of time sufficient to convert the fluid pre-polymer material into a non-fluid hydrophilic polymer;
(j) opening the mold parts;
(k) removing the lens;
(l) hydrating the ophthalmic lens; and
(m) packaging the ophthalmic lens. - View Dependent Claims (41, 42, 43, 44, 45, 46)
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47. An apparatus for molding a polymer comprising:
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(a) a first mold part having a first molding surface; and
(b) a second mold part having a second molding surface, the second molding surface capable of containing a sample of polymer, the sample having a volume;
the mold parts being adapted to mate together to form a mold cavity in the shape of an ophthalmic lens having a variable volume at least between a first volume and a second volume, the second volume being greater than the first volume;
wherein the mold parts have sufficiently small clearance such that gas escapes from the mold cavity, and none of a sample of material escapes from the mold cavity when the mated mold halves are subjected to a predetermined force with the sample in the mold cavity.
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Specification