Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
  • B29C39/003—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor characterised by the choice of material
  • B29C39/006—Monomers or prepolymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
  • B29C39/02—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles
  • B29C39/10—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles incorporating preformed parts or layers, e.g. casting around inserts or for coating articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D11/00—Producing optical elements, e.g. lenses or prisms
  • B29D11/0073—Optical laminates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B23/00—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose
  • B32B23/04—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose comprising such cellulosic plastic substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B23/08—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose comprising such cellulosic plastic substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B23/00—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose
  • B32B23/20—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose comprising esters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
  • B32B27/308—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising acrylic (co)polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/40—Layered products comprising a layer of synthetic resin comprising polyurethanes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
  • C09D175/04—Polyurethanes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2011/00—Optical elements, e.g. lenses, prisms
  • B29L2011/0016—Lenses
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2255/00—Coating on the layer surface
  • B32B2255/10—Coating on the layer surface on synthetic resin layer or on natural or synthetic rubber layer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2255/00—Coating on the layer surface
  • B32B2255/26—Polymeric coating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/40—Properties of the layers or laminate having particular optical properties
  • B32B2307/412—Transparent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/552—Fatigue strength
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/558—Impact strength, toughness
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/71—Resistive to light or to UV
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2551/00—Optical elements

Definitions

• Many methods and devices are known in the art for incorporating photochromic characteristics into an ophthalmic lens.
• One example of a method known in the art includes imbibing or infusing photochromes into the host material or base lens from a transfer layer (that is subsequently removed) prior to formation of the finished lens product.
• Another example of a method known in the art includes incorporating photochromes into a lens by imbibing or coating a photochromic composition onto the surface of a base lens.
• Yet another example of a method known in the art includes incorporating photochromes into a finished lens product by combining a prepared photochromic insert or "laminate" with base lens material, typically via an injection molding process. The following are illustrative examples of such methods known in the art.
• the imbibing process was one of the first processes to be used to impart photochromicity to plastic lenses.
• U.S. Patent No. 4,286,957 to Naour-Sene describes this process. Further refinements were discussed in U.S. Patent No. 4,880,667 to Welch.
• Various improvements to this imbibing process have been developed, such as described in U.S. Patent No. 5,130,353 to Fisher et. al., and U.S. Patent No. 5,185,390 to Fisher et. al. These two patents suggest improvements to the transfer process with a unique transfer layer. It was recognized early on that the plastic resins used to make ophthalmic lenses do not provide the best host material for photochromes.
• the photochromes do not activate easily and fatigue or wear-out in a short period of time.
• a strong activation darkness to near sunglass darkness is desired in the marketplace.
• Another desired characteristic of a photochromic lens is that it should maintain at least 70 percent of its original activation darkness after two years of wear. This is one of the limitations to putting photochromes into polymeric host materials that are used to form the bulk of the lens.
• U.S. Patent No. 5,728,758 to Smith describes a photochromic article in which the organic polymeric host material has been impregnated with photochromes prior to formation of the finished lens product.
• one of the drawbacks of incorporating photochromes directly into the polymeric host material is the problem of fatigue or light fatigue. Photochromes are believed to lose their ability to change color specifically resulting from the irreversible decomposition of the photochromic compound, which occurs due to repeated exposure to UV light over time.
• the '758 patent specifically address this problem by using a unique combination of monomers and surface coating compositions to improve abrasion resistance, chemical attack and improved fatigue resistance.
• the '430 patent describes a process that includes the steps of treating the surface of a polymeric substrate to provide reactive groups, applying a polymerizable composition to the surface, exposing the coated substrate to radiation to improve adhesion, and applying and curing a photochromic composition to the coated surface.
• the '430 patent addresses a method of producing commercially acceptable "cosmetic" standards for photochromic and non- photochromic optical coatings that are applied to lenses.
• a major limitation of the photochromic coating approach is the poor scratch resistance of such a coating even with another hard coating on top of the photochromic coating. Additionally, if the photochromic coating is scratched, it will result in streaks of areas on the lens that do not activate.
• the photochromic laminate or wafer includes inner and outer resin sheets (or protective layers), which sandwich a photochromic cellulose acetate butyrate layer.
• the unitary photochromic laminate is thereafter placed inside a mold cavity, after which a molten polycarbonate resin is injected into the cavity and fused to the back of the photochromic laminate.
• the lens is then cooled to room temperature and the finished product is an injection molded, photochromic polycarbonate lens.
• the shortcomings of coating photochrome products onto the surface of a lens have to do primarily with coating thickness and the creation of segmented, multi-focal lenses.
• a coating of about 25 ⁇ m or more is needed to incorporate a sufficient amount of photochromic compounds to provide the desired light blocking quality in the lens when the compounds are activated.
• a coating of this thickness is not well suited for application on the surface of a segmented, multi-focal lens because it is too thick.
• a coating of this thickness creates such problems as the creation of an unacceptable segment line, as well as coating thickness uniformity issues around the segment line.
• Bhalakia patent adequately addresses the issue of making laminates used in injection-molding, through improvement of laminate materials and properties. However, the issues addressed by Bhalakia do not include providing a laminate or insert that may be used in a cast- lens manufacturing process.
• Figure 1 illustrates a photochromic lens according to a preferred embodiment of the present invention.
• Figures 2A-2D illustrate a photochromic film, as embedded in a photochromic lens of Figure 1), according to a preferred embodiment of the present invention.
• one embodiment according to the present invention relates to a photochromic lens comprising a front cast resin layer 1, a photochromic film 2, and a back cast resin layer 3.
• a preferred embodiment would include a photochromic lens made from a cast resin that is either thermoset or radiation-set.
• the photochromic lens may be either a finished product or a semifinished product.
• a photochromic lens may include a photochromic film 2 including at least one protective layer 4 and a photochromic layer 5 (as shown in Figure 2, examples (A) 1 (B) and (C)).
• the photochromic film may include just a photochromic layer 5 (as shown in Figure 2, example (D)).
• the photochromic film 2 is bonded or adhered strongly to a casting resin layer 1, 3 during a casting process (as shown in Figure 1).
• the photochromic film 2 in the form of a laminate may be optimized as a host for a photochromic dye to provide for maximum performance of the dye.
• additional embodiments according to the present invention would include a photochromic film 2 having at least one protective layer 4 and a photochromic layer 5, in a variety of orientations to one another (e.g., Figure 2, examples (A), (B), and (C)).
• additional hard coating, primer, or barrier coatings that may be applied onto the front surface of the protective layer 4 (e.g., for enhancing adhesion and other performances), the front surface meaning the surface of the protective layer 4 facing away from the photochromic layer 5.
• the photochromic layer 5 may also have such hard, primer or barrier coatings applied before placement into the cast lens.
• Additional embodiments according to the present invention may include a cast photochromic lens including a number of layers and/or combinations of layers, comprising, for example, protective layers, photochromic layers or films, and/or additional coating layers (e.g. hard coating, primer layers, and/or other barrier layers)(not shown).
• a cast photochromic lens including a number of layers and/or combinations of layers, comprising, for example, protective layers, photochromic layers or films, and/or additional coating layers (e.g. hard coating, primer layers, and/or other barrier layers)(not shown).
• additional coating layers e.g. hard coating, primer layers, and/or other barrier layers
• a suitable photochromic film (laminate) is disclosed in U.S. Patent Application Serial No. 10/938,275 entitled Photochromic Polyurethane Laminate, filed September 9, 2004, which is herein incorporated by reference.
• a preferred material for the protective layers 4 of the photochromic film 2 should have good compatibility with the lens casting material.
• compatibility it is meant that the adhesion between the protective layer 4 and the front cast resin layer 1 formed by the lens casting material is sufficient to pass ordinary tests for eyewear lenses without damage or chemical attack to the protective layers 4 of the photochrome film 2 (e.g. FDA drop-ball test, drilling and mounting tests).
• Examples of preferred materials for the protective layers 4 of the photochromic film 2 include acrylate resins, cellulose esters, and polycarbonate resins. Suitable hard coatings known in the art may further protect such protective layer resins to prevent the casting resin from chemically attacking the protective layer resins during processing.
• Preferred materials for the photochromic layer 5 of the present invention would include, for example, plastic host resins having a glass transition temperature, T 9 , of less than 50 0 C, and more preferably, below 3O 0 C. These plastics tend to be mechanically soft which is ideal for the photochromes to activate and de-activate. When the photochromic dyes absorb UV light, typically a carbon- oxygen bond in the photochromic dye molecule is broken and the dye molecule rotates into a form that absorbs visible light.
• a soft plastic host for the dye that would facilitate this action preferably would include a class of plastic hosts, such as polyurethanes. However, historically, this mechanical softness of plastic hosts has been shown deficient when such materials are used as ophthalmic lens materials.
• an ophthalmic lens contemplated for use with the present invention would include encapsulation of a host urethane resin, such as a photochromic layer 5, within an ophthalmic lens.
• a preferred thickness of the photochromic layer 5, namely the photochromic urethane layer 5, would preferably be 10 mil or less, more preferably 4 mil or less and most preferably, to 2 mil or less.
• Preferred polyurethane photochromic host materials would include, for example, thermoplastic and thermoset polyurethanes. Examples of such host materials are disclosed in U.S. Patent Nos. 4,889,413, 6,107,395, and 6,166,129, and U.S. Patent Application Serial No. 10/938,275, which are herein incorporated by reference.
• the polyurethane composition would preferably include the following: 0.05% to 6% pbw of photochromic compound(s), and a stabilizer package: 0.5% to 6% pbw of light stabilizer(s), 0.5% to 6% pbw of antioxidant(s), 0.5% to 6% pbw of UV absorber(s).
• the photochrome film 2 would preferably have a thickness no greater than 40 mil.
• any lens casting resins available on the market and known in the art would be suitable to produce the photochromic lens of the present invention.
• casting resins would include CR-39 from PPG (or equivalent from Great Lakes Chemicals denoted by the tradename of RAV-7) and MR series cast resins from Mitsui.
• cast resins that are curable by radiation energy e.g., UV
• the radiation curing process is advantageous in that it will not interfere or degrade the photochromic dyes due to their protection inside the laminate.
• radiation curable cast resins would include, for example, those resins based on aery I ate chemistry.
• the cast resin for the front protective layer 4 of the photochromic film 2 should not include UV absorbers, which would significantly absorb or block the activation wavelength of the photochromic dye.
• the photochromic layer 5 of the photochromic film 2 would provide adequate UV protection to the eyes, as the photochromic dyes imparted to the photochromic layer 5 are extremely efficient absorbers of UV.
• Examples of manufacturing the photochromic lens as contemplated in the present invention would include, for instance, a cast molding process, in which a photochromic film 2 is first placed into a cast mold. Thereafter, a cast resin 1,3 may also be introduced into the cast mold and the lens would be cured, forming an integrate photochromic cast lens.
• the photochromic film 2 may be placed in any number of orientations within the mold, depending upon desired results and lens processing applications.
• One embodiment for manufacturing the lens of the present invention would include the steps of preparing a photochromic film 2, as earlier described; forming discs of the film into wafers, preferably having a curve matching the front base curve of the lens to be produced; preparing a cast setup comprising a front mold, a formed wafer, a back lid (mold), in a cast gasket; pouring a cast resin into the front cavity formed by the front mold and the wafer, and the back cavity formed by the wafer and the back lid (mold); and curing the cast resin to form the photochromic lens.
• Forming of the photochromic film 2 may be done by a variety of different ways familiar to those in the arts.
• lens forming techniques may include, for instance, compression forming and vacuum forming.
• a cast setup used to produce polarizing lenses from cast resins could also used to cast the photochromic lens of the present invention without any modification.
• Another embodiment for manufacturing a lens as contemplated by the present invention includes incorporation of photochromes into the polyurethane plastic, and thus the photochromic film 2, after the polyurethane has been formed (e.g., after urethane monomers and catalyst have reacted to fully form polyurethane).
• This is contrary to the teaching of U.S. Patent No. 4,889,413 (herein incorporated by reference), which describes incorporation of photochromes into the urethane monomer/catalyst mixture, prior to formation of polyurethane.
• the teaching of the '413 patent describes a the method of preparing and assembling a lens unlike that of the present invention.
• the '413 patent describes assembly of pre-cast lenses (either plastic or glass), between which a photochromic host is introduced and thereafter cured.
• One embodiment of a method contemplated for use with the present invention may include the steps of: dissolving an appropriate amount of photochromic dye into a polyurethane resin with an appropriate solvent; casting the resultant solution on a smooth surface, to allow the solvent to evaporate; placing the resulting sheet or film of photochromic polyurethane into a mold with a thermoset casting monomer liquid and catalyst; and completing a curing or reaction step of the thermoset monomer into a thermoset, fully cured lens with the polyurethane film encased inside the thermoset lens.
• This particular embodiment would result in a photochromic thermoset, cast lens with improved photochromic properties.
• one does not need to mix the photochromes with the polyurethane monomers first.
• One has the option of putting the polyurethane in a laminate as described above or not in a laminate inside the lens (plastic host).
• a photochromic film was prepared according to the examples in U.S. Patent Application Series No. 10/938,275.
• the polyurethane layer is 40 ⁇ m thick, and the protective layers are 76 ⁇ m cellulose acetate butyrate (CAB) films (K-Mac).
• CAB cellulose acetate butyrate
• the polyurethane layer and protective layers were bonded together to form a photochromic laminate.
• the laminate was masked with a 3M film (24S56W).
• a 70- mm disk was die-cut off from the above laminate, and formed into a 6-base laminate wafer through a thermo-vacuum forming process. The temperature was 255 0 F, and the forming time was 200 seconds.
• a 70-mm lens cast gasket and two 6-base glass molds (front and back) were used to cast the photochromic lens.
• the masked film is thereafter removed prior to placement of the laminate wafer into the gasket.
• the laminate wafer was fixed in the gasket about 1 mm away from the front mold surface with help of a spacer.
• a clear UV-curable cast resin from OptiCast was injected into the front and back cavities.
• the front cavity is formed by the front mold and the photochromic film.
• the cast resin in the above setup was cured under a 12-mW/m 2 exposure for 10 minutes.
• the result was a cast resin lens having the photochromic film embedded in it.
• the unactivated transmission of the lens was measured as 70%.
• the activated transmission after exposure to a Xenon lamp under 20 W/m 2 intensity of UV was measured to be 19%. This demonstrated good photochromic activity.
• the mold and gasket assembly was placed in a water bath and cured in a cycle that ramps the lens up to 90oC over a 20 hour period.
• the resultant thermoset, cast lens is then separated from the glass molds.
• the lens had a refractive index of 1.55.
• the lens sample was then fatigued by exposure to a Xenon lamp with an ultraviolet light output of 30 Watts/Square Meter for 144 hours. This simulates actual wear of the lens by someone for a two year wear period.
• the photochromic performance remaining was 97%. This compares to the performance of the commercial photochromic polycarbonate Quantum (Transitions Optical, Inc.) lens product that is believed to be only a 65% remaining performance. Thus, the photochromic film in the cast lens was very fatigue resistant and had longer life than the prior art.
• a photochromic film was prepared according to the examples in U.S. Patent Application Series No. 10/938,275.
• the polyurethane layer is 40 ⁇ m thick, and the protective layers are 350 ⁇ m thick polycarbonate films.
• the polyurethane layer and protective layers were bonded together to form a photochromic laminate.
• the laminate was masked with a 3M film (24S56W).
• a 70-mm disk was die-cut off from the above laminate, and formed into a 6-base laminate wafer through a thermo-vacuum forming process. The temperature was 255 0 F, and the forming time was 200 seconds.
• a 70-mm lens cast gasket and two 6-base glass molds (front and back) were used to cast the photochromic lens.
• the masked film is thereafter removed prior to placement of the laminate wafer into the gasket.
• the laminate wafer was placed against the front mold surface and placed into the gasket with the back mold.
• a clear UV-curable cast resin from OptiCast (OPIV-B) was injected into the back cavity.
• the cast resin in the above setup was cured under a 12-mW/m 2 UV exposure for 7 minutes.
• the result was a cast resin lens having the photochromic laminate fused to the front of it.
• the unactivated transmission of the lens was measured as 79%.
• the activated transmission after exposure to a Xenon lamp under 12 VWm 2 intensity of UV was measured to be 19%. This demonstrated good photochromic activity.
• a photochromic film was prepared by laminating 13.5 mil thick CAB film (Kodacel K7896, made by Eastman Kodak) for both top and bottom protective layers and 38 micron photochromic layer (polyurethane).
• the laminate was masked with 3M protective masking film (24S56W) on both sides then a 86 mm disk in diameter was cut-out from the above laminate. It was formed into a 6 base laminate wafer through a thermo-vacuum forming process. The forming temperature was 235 0 F and forming time was 150 seconds. It was further cut to 72.6 mm in diameter to fit the size of casting mold. It was further cut by 3 mm on two locations to allow flow of the cast resin around it.
• a 73 mm casting mold and two 6 base glass molds were used for front and back to cast a photochromic lens.
• the masked film is thereafter removed prior to placement of the laminate wafer into the gasket.
• Said formed photochromic film was placed in the mold about 1 mm away from the front mold surface with help of a spacer.
• Thermo-set resin RAV-7 (made by Great Lakes Chemical) without UV absorbing agent was injected to fill both front cavity and back cavity which were separated by the photochromic film.
• the cast resin in above setup was thermally cure in normal condition.
• the result was a cast resin lens having the photochromic laminate fused to the front of it.
• the unactivated transmission of the lens was measured as 82.4%.
• the activated transmission after exposure to a Xenon lamp under 12 W/m2 intensity of UV was measured to be 16%. This demonstrated good photochromic activity.
• a photochromic film was prepared by laminating 12 mil thick polycarbonate film (1151 by Teijin Kasei America) for both top and bottom protective layers and 38 micron photochromic layer (polyurethane).
• the polycarbonate film was applied with UV curable hardcoat as barrier coating on one side in advance. The hardcoated side was placed outside of lamination that later contacts casting resin. Without this barrier coating, this casting resin monomer has been shown to cause the polycarbonate film to turn white and, therefore, usable.
• the laminate was masked with 3M protective masking film (24S56W) on both sides then a 86 mm disk in diameter was cut-out from the above laminate. It was formed into a 6 base laminate wafer through a thermo-vacuum forming process.
• the forming temperature was 285 0 F and forming time was 250 seconds. It was further cut to 72.6 mm in diameter to fit the size of casting mold. It was further cut by 3 mm on two locations to allow flow of the cast resin around it.
• a 73 mm casting mold and two 6 base glass molds were used for front and back to cast a photochromic lens.
• the masked film is thereafter removed prior to placement of the laminate wafer into the gasket.
• Said formed photochromic film was placed in the mold about 1 mm away from the front mold surface with help of a spacer.
• Thermo-set resin RAV-7 (made by Great Lakes Chemical) without UV absorbing agent was injected to fill both front cavity and back cavity which were separated by the photochromic film.
• the cast resin in above setup was thermally cure in normal condition.
• the result was a cast resin lens having the photochromic laminate fused to the front of it.
• the unactivated transmission of the lens was measured as 90.0%.
• the activated transmission after exposure to a Xenon lamp under 12 W/m2 intensity of UV was measured to be 19%. This demonstrated good photochromic activity.

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