US20080071002A1

US20080071002A1 - Custom monomers and polymers for spectacle lenses

Info

Publication number: US20080071002A1
Application number: US11/726,055
Authority: US
Inventors: Jagdish Jethmalani; Gomaa Abdel-Sadek; Jeffrey Chomyn; Erdem Cetin; Lawrence Sverdrup; Shawn McCarty; Junhao Ge
Original assignee: Individual
Current assignee: EssilorLuxottica SA
Priority date: 2006-03-20
Filing date: 2007-03-20
Publication date: 2008-03-20
Also published as: WO2007109295A2; MX2008011854A; EP1996972A1; WO2007109295A3; AU2007239006B2; AU2007227252B2; US20070285799A1; EP1999497A2; CA2644728A1; AU2007227252A1; CN101416095A; US20070285617A1; JP2009530689A; MX2008011760A; JP5249195B2; US7950799B2; WO2007109308A1; CA2645936A1; AU2007227239A1; JP2013231995A

Abstract

Monomers and polymers used in making spectacle lenses are disclosed. A thermal curing process is disclosed that includes a latent thermal cationic acid generator and optionally a cationic photoinitiator.

Description

The present application claims the benefit of U.S. Provisional application Ser. No. 60/784,394 filed 20 Mar. 2006 which is incorporated herein by reference.

RELATED ART

U.S. Pat. Nos. 6,989,938 (the '938 patent) and 6,813,082, each to Bruns, describe wavefront aberrators and methods for manufacturing the same. The '938 patent describes how a unique refractive index profile can be created in a monomer layer by controlling the extent of curing of the monomer in different regions across the surface, thus creating a wavefront aberrator. The '938 patent further describes a method that allows one to achieve a unique refractive index profile through the creation of regions with varying degrees of cure. Additionally, the PCT application with the Publication Number WO 2006/029264 describes in more detail materials that may be used to correct high order aberrations.
Wavefront aberrators that correct for both low order and high order aberrations are known. These aberrators contain a polymer layer wherein the polymer layer can be programmed by curing to have a variable index of refraction profile or a constant index of refraction throughout the aberrator. See for example the following U.S. Pat. Nos. 6,813,082; 6,989,938; 6,712,466; 6,840,619; 6,942,339 and 7,021,764 all of which are incorporated herein by reference.
Co-pending U.S. application Ser. No. 10/936,030 Document No. 2006/0052547 discloses monomer and polymers useful in making optical elements and is incorporated herein by reference in its entirety.

SUMMARY

A preferred embodiment provides a composition to form an optical element or lens material that may comprise: a matrix polymer having a monomer mixture dispersed therein, the matrix polymer being selected from the group consisting of epoxy monomers, oxetane monomers, and mixture of epoxy and oxetane monomers. Another preferred embodiment provides a method for making such a composition and said optical element. The method may comprise intermixing, in any order, the matrix monomers, latent thermal cationic acid generator for cationic ring opening polymerization of epoxy and oxetane functional groups, and/or cationic photoinitiators chosen from aryl and alkyl sulfonium and iodonium photo acid generators. The monomers can be cured partially or fully with heat. If cured partially, the addition of a photoinitiator will allow the optical element to be programmed with a variable index of refraction profile and/or etched with a logo by exposure to light (UV, laser, etc). After the programming or logo etching (writing) the composition is heated further to cure substantially all of the remaining unreacted monomers.
Another preferred embodiment provides a composition that may comprise: polyepoxy and/or polyepisulphide and/or polyisocyanate along with at least one polythiol compound and olefin-terminated monomer as individual components (or mixed as commercially available Norland Optical Adhesive) in the presence of amine catalyst and photoinitiator.
Other preferred embodiment provide a method for making a programmable lens. The method may comprise using a very well degassed formulation in between two CR-39 sheets separated with the spacer, thermal cure the assembly for suitable time at accommodated temperature, grind the assembly to be fit in the desired frame, write the desire power and flood it, heat it to delaminate the two CR-39 sheets, secure the final designed lens in the frame.
Additional preferred embodiments provide a composition comprising: polyepoxy and/or polyepisulphide and/or polyisocyanate along with at least one polythiol compound in the presence of amine catalyst.
Another preferred embodiment provides a method for making a lens blank. The method comprises using: two CR-39, polycarbonate, or 1.6 lens blanks grinded to the required geometry and one of them has two holes close to the edges allow to inject and to get rid of bubbles; glued rings placed over each other to make the desired thickness to be used as a spacer between the two lens blanks in order to make mold-shape design; aluminum tape to be wrapped around the mold to keep the mold from any geometrical change; and a mix of polyfunctional monomers selected from the group consisting of sandwiched between the first and second lenses selected from the group consisting of polyepoxy and/or polyepisulphide and/or polyisocyanate along with at least one polythiol compound in the presence of amine catalyst.
A preferred embodiment provides a composition comprising: polyepoxy and/or polyepisulphide along with at least one polythiol compound and olefin-terminated monomer in the presence of amine catalyst, photoinitiator, and stabilizer.
Another preferred embodiment provides a method for making such spectacle lens. The method may comprise using a very well homogenized and degassed formulation injected between two lens blanks (base and cap) separated with a 500 μm photocurable spacer, thermal cure the assembly for suitable time at accommodated temperature, grind and polishing the assembly to be 0.5+0.5+0.8 mm for cap, gel, and base, respectively. Write the desire power followed by flood curing it, add the hard and anti-refraction coats, grind it to the final shape that fit with the required frame, and frame it.
Also described herein is a polymerizable composition for making a spectacle lens. A high order aberration correction may be written on this lens. The compositions may comprise polyepoxy, polyepisulfide and/or isocyanate along with at least one polythiol compound and olefin-terminated monomer in the presence of amine catalyst and photoinitiator as well as stabilizer. The composition may comprise 60% of Ene+Thiol and 40% of Epoxy+Thiol. The gel may be soft, provide a Δn of 0.019, and provide fast diffusion of free monomers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The term “Spectacle Lens” is used herein in its usual sense and includes, e.g., a polymerizable formulation built up by mixing multifunctional smaller molecules of monomeric materials together, pre-polymers, oligomers, crosslinked polymers, blends, and interpenetrating polymer networks.
A compound represented by general formulas (1) used in this invention is characterized in having mercapto groups:
R
SH)_n (1)
Wherein when n is 3, R is an organic residue:
When n is 4, R is an organic residue:
A compound represented by general formulas (2) used in this invention is characterized in having epoxy, episulfide and/or isocyanate groups:
R
X)_n (2)
For epoxy,
Wherein when n is 2, R is an organic residue:
Wherein when n is 3, R is an organic residue:

Wherein when n is 3.6, R is an organic residue:

For polyisocyanate,
X=*-NCO
Wherein when n is 2, R is an organic residue:

For polyepisulfide,

Wherein when n is 3, R is an organic residue:

Wherein when n is 3.6, R is an organic residue:
A compound represented by general formulas (3) used in this invention is characterized in having Ene (allyloxy or acrylate) groups:
R
Y)_n (3)
For allyl-terminated Ene,

Wherein when n is 2, R is an organic residue

Wherein when n is 3, R is an organic residue
A catalytic amount of amine is chosen from the group included, but not limited to, tetrabutylaminobromide, dimethylbenzyl amine, triethylamine, or propylamine.
The following examples illustrate the practice of the present invention but should not be construed as limiting its scope.
In the following examples physical properties for an example formulation and resin prepared were evaluated as following: (1) A refractive index (n_D) measured at 25° C. using a digital Reichert Mark II Plus refractometer. (2) The viscosity was measured at 25° C. using a digital Brookfield DV-II+viscometer. (3) The adhesion strength of polymerized film between two bonded/glued lens blanks was measured at room temperature using DeFelsco Percision Adhesion Tester. (4) The formulations were made/mixed at 70±5° C. using Bushi Rotavapor R-114. (5) Impact resistance: According to USA FDA standards, a falling ball test was conducting by dropping steel balls (11 g, 16.33 g and 66.75 g) on a lens with a center thickness of 4.0 mm from the height of 120 cm. The results were rated with one of three grades; A: no change, B: star crack and C: steel ball penetration.

Example 1

Materials: Starting materials were either commercially available or synthesized. Trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(2-mercaptoacetate) and pentaerythritol tetrakis(3-mercaptopropionate), tetrabutylammonium bromide (TBABr), dimethylbenzyl amine (DMBA), bis[4-(glycidyloxy)phenyl]metane (bisphenol F diglycidyl ether), bisphenol A diglycidyl ether, di(ethylene glycol) bis(allyl carbonate) (CR 39), benzophenone, triallyl triazine trione and triallyloxy triazine, were purchased from Aldrich. 4-Mercaptomethyl-3,6-dithia-1,8-octanedithiol (MDO) was synthesized using well know synthetic techniques. Poly[(phenylglycidyl ether)-co-formaldehyde] (Epoxy Novolac Resin, D.E.N. 438) was purchased from The Dow Chemical Company. Araldite RD-2 (butanediol diglycidyl ether) was purchased from Huntsman. 1,1,1-Tris(p-hydroxyphenyl)ethane triglycidyl ether THPE/GE was purchased from Chemist Electronic Materials L.P. Diallyl maleate (DIAM), triallyl trimellitate (TATM) and diallylether Bisphenol A were purchased from BiMax. 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184) was purchased from Ciba. N-nitrosophenylhydroxylamine aluminium salt (N-PAL) was purchased from Albemarle Corp.
5.3486 g of D.E.N. 438, 2.6433 g of Diallylether Bisphenol A, 6.8139 g of Trimethylolpropane tris(3-mercaptopropionate), 0.0148 g of Irgacure 184, 0.1485 g of Tetrabutylammonium bromide, and 0.003 g of N-PAL were weighed, added to a clean vial and mixed with a magnetic stirrer@70° C. (water bath) for 10 min and named as Part I.
In another clean vial were added 5.9456 g of Trimethylolpropane tris(3-mercaptopropionate), 2.4001 g of Diallylether Bisphenol A, 4.0001 g of Di(ethylene glycol) bis(allyl carbonate), 0.0026 g of N-PAL, and 0.0191 g of Benzophenone and mixed with a magnetic stirrer@70° C. (water bath) for 10 min and named as Part II.
Part I and Part II were mixed well and degassed to from a monomer/polymer mixture. Two 1.6 index lens blanks (base & cap) were glued to each other through a UV curable glue containing polystyrene beads with 500 μm (micron) diameter. The glue with beads was dispensed close to the edge of the cap and then pressed onto the base and photocured to give a space of 500 μm between the base and cap for injecting the monomer/polymer mixture into it to form a lens assembly. The lens assembly was transferred into an oven with well controlled temperature and it was heated for 5-8 hr@75° C. to partially cure the monomer/polymer mixture. The lens assembly was then grinded and polished to the desired thickness. It was transferred to Lens Writer lab to write (etch) a logo with a laser light. The lens assembly was then flood cured with UV light to cure the remaining monomers. The spectacle lens was grinded, polished and placed in an eyeglass frame.
Lens Blank
Also described herein are polymerizable compositions for lens blanks with high refractive index comprising polyepoxy and/or polyepisulfide and/or polyisocyanate along with at least one polythiol compound in the presence of amine catalyst.
The term “Lens Blank” is used herein in its usual sense and includes, e.g., a polymerizable formulation built up by mixing multifunctional smaller molecules of monomeric materials together, pre-polymers, oligomers, crosslinked polymers, blends, and interpenetrating polymer networks.
A catalytic amount of amine is chosen from the group included, but not limited to, tetrabutylaminobromide, triethylamine, or propylamine.

Example 2

Lens Blank

Starting materials described in Example 1 were also employed in this example. Additionally, CR-39 lens blanks grinded to the required geometry were purchased from Vision-Ease, Indonesia. Glued rings of tape were used as an assembly spacer—product # 100-00089-01 from Cellotape. Irganox 1010 was purchased from Ciba.
Epoxy D.E.N. 438 heated in an oven at a temperature of 75° C. to melt the material. In a clean 500 mL capacity flat-bottom flask was placed 28.7 g of Epoxy D.E.N. 438, 34.2 g of Trimethylolpropane tris(3-mercaptopropionate) and 0.063 g of TBABr. Hock the flask to the rotary evaporator and immersed it into a water bath at a temperature of 60±5° C. The flask was allowed to rotate at the maximum speed of the rotavapor for 45-60 min or until an homogeneous and clear mixture is formed. The flask was removed from the rotavapor and the hot viscous mixture was poured into a clean 300 mL glass beaker. The refractive index of a cured layer of the mixture was measured immediately. A layer of the mixture was made using 2 slides separated by 10 mil wire spacers. The mixture layer was then cured before taking the refractive index measurement. The beaker with the mixture was placed into a desiccator and a vacuum was applied until all bubbles were gone. The vacuum was broken down slowly with dry Argon gas. The processes of the previous two sentences were repeated three times.
Glued rings were placed over each other to make a desired thickness gasket to be used as a spacer between the two lens blanks to make a sandwich lens configuration. Two CR-39 lens blanks were grinded to the required geometry. In one of those CR-39 lens blanks, two small holes were drilled at two edges of the lens opposite each other. These holes were made to allow easy injection of the monomer/polymer formulation mixture and removal of air and bubbles from the formulation. The other CR-39 lens blank was left as it is. The two grinded CR-39 lens blanks were placed together in a mold-shape using the spacer made of the glued rings at the edges. Aluminum tape was placed around the mold to secure the formulation liquid inside the mold. The formulation was slowly injected through one of the two holes made in the CR-39 lens blank until the whole space inside the mold was filled and the air bubbles were removed through the other hole. The mold with the formulation was allowed to stand horizontally for 10-15 mm.
The mold was transferred with the material into the desiccator and a vacuum was applied until no bubbles were visible in the mold. The vacuum was slowly broken down with dry Argon. The processes described in the previous two sentences was repeated three times. The degassed mold along with the two slides were carefully transferred into the oven and were heated for 5-6 hr at 75-80° C. The temperature of the oven was raised to 100° C. and continued to heat the mold for 2 more hours and then one more hour at 120° C. The oven was allowed to cool down and then the mold and microscope slides were taken out. The aluminum tape around the molds was removed. The mold assembly was transferred to the lens machine shop to be grinded to the desired geometry. Refractive index and the UV transmittance of cured materials were measured.
Slab/Lens
Also disclosed herein are polymerizable compositions for making a spectacle lens with high refractive index. In some variations the lens may be written on in a short time. The compositions may comprise polyepoxy and/or polyepisulfide and/or polyisocyanate along with at least one polythiol compound and olefin-terminated monomer in the presence of amine catalyst and photoinitiator. The compositions may comprise Norland adhesive, provides fast curing and provides slow diffusion of free monomers.
A catalytic amount of amine is chosen from the group included, but not limited to, tetrabutylaminobromide, Dimethylbenzyl amine, triethylamine, or propylamine.

Example 3

Slab/Lens

Starting materials described in Examples 1 and 2 were also employed in this example. Additionally, CR-39 triallyl trimellitate was purchased from Aldrich. Norland Optical Adhesive NOA was purchased from Norland Products Inc. CR-39 sheets were purchased from Fasta Tek Optics Inc. Wire with 0.040″ diameter for use as a lens assembly spacer was purchased from Small Parts, Inc. Ceramic tape Double-Coated was purchased from 3M.
4.9886 g of 1,1,1-Tris(p-hydroxyphenyl)ethane triglycidyl ether (Epo #4)+4.1647 g of bis[4-(glycidyloxy)phenyl]metane (Bisphenol F diglycidyl ether) (Epo #7)+4.0330 g of Norland Optical Adhesive NOA-61+0.9899 g of diallyl maleate (DIAM)+7.9160 g of pentaerythritol tetrakis(2-mercaptoacetate) (Thiol #27) were weighed, added to a clean vial and mixed with a magnetic stirrer (70° C. (water bath) for 10 min. 0.0217 g of dimethylbenzyl amine (DMBA) was added with a micropipette and the mixture was stirred again. The formulation was degassed under vacuum at room temperature resulting in a formulation mixture.
A mold of 3″×2″×1 mm dimensions was made using two transparent CR-39 sheets, a wire spacer with a 0.04″ thickness, and ceramic double-coated tape. The degassed formulation mixture was injected into the mold while it was in vertical orientation to get rid of the bubbles. The whole assembly was degassed, transferred into a cleaned and well temperature controlled oven, and baked at the temperature of 75° C. for 4-5 hr whereupon the formulation mixture turned into a gel material. The mold with the gelled material was then cut and grinded to the shape of an eyeglass frame. The grinded assembly was transferred to Lens Writer to write and flood cure it using the appropriate UV light source. The assembly was heated to 110-120° C. to delaminate the two CR-39 sheets and re-fit the so called programmed lens in the frame. An impact resistance test was performed by dropping two steel balls, separately, weighing 16.33 g and 66.75 g. Each ball was dropped onto the lens from the height of 120 cm and the result was “A” (neither change, star crack, nor ball penetration was observed).
Thermally Initiated Cationic Ring Opening Polymerization
Also described herein are monomeric and oligomeric materials and stabilized mixtures of monomeric and oligomeric materials useful for making optical elements such as lenses via thermally initiated cationic ring opening polymerization with latent thermal cationic initiators or both independently on demand with latent thermal and photo cationic initiators.
In one embodiment of the present invention an optical element is made by preparing a formulation mixture that contains epoxy monomers, oxetane monomers or mixtures of epoxy and oxetane monomers and a thermal initiator such as a latent thermal cationic acid generator. The formulation is then formed into a layer less than about 5 mm thick, advantageously less than about 1 mm thick and preferably about 0.5 mm thick. Preferably, this layer is formed in between two ophthalmic lens blank, such as 1.6 index plastic lens blanks. The layer is then subjected to heat to cure the monomers present in the formulation. This thermal curing can be complete or it can be partial. If the layer is partially cured then radiation (UV light, laser, etc) energy can be used to further cure the layer when a photoinitiator is also added to the formulation. The further curing can be used to program the layer to have a variable index of refraction in order to correct for high order optical aberrations. Also, a logo could also be written on the layer in an inconspicuous area that does not affect the performance of the optical element. After the programming or logo writing is completed the layer is then exposed to further heat to fully cure substantially all monomers in the layer. This forms a stable optical element.
Another preferred embodiment provides a composition that may comprise an epoxy monomer, oxetane monomer, and epoxy-oxetane monomer mixtures that comprises a cationic photoinitiators chosen from aryl and alkyl sulfonium and iodonium photo acid generators in addition to a thermal latent cationic photoacid generator. Another preferred embodiment provides a method for making such a composition. The method may comprise: providing a composition, the composition comprising a matrix polymer having a monomer mixture dispersed therein; the matrix polymer being selected from the group consisting of epoxy monomers, oxetane monomers, and mixture of epoxy and oxetane monomers undergoing thermal ring opening epoxy or oxetane or epoxy-oxetane polymerization and copolymerization. Preferably, the polymerization of the monomer mixture comprises thermal polymerization activated in the temperature range of 50 to 100° C. Another preferred embodiment provides a method of such epoxy or oxetane or epoxy/oxetane monomer mixtures to include both thermal and photo acid initiators which are capable of initiating cationic ring opening polymerization. Another preferred embodiment involves partial cure of such epoxy, oxetane, or epoxy/oxetane matrix containing both photo and thermal cationic acid generators at the preferred temperature range of 60 to 75° C. Another preferred embodiment involves photochemically curing the partially cured matrix via actinic radiation at ambient or elevated temperature to create a photo programmable matrix. Another embodiment comprises of a selection of photo acid generator, such as aryl and alkyl sulfonium photo acid generators, which exhibits high thermal stability without undergoing thermal decomposition to generate super acids under thermal cure conditions between 60° to 100° C. Another preferred embodiment involves the incorporation of thermal latent cationic initiators chosen from Nacure® Super XC-7231, ammonium hexafluorantimonate, and Nacure® Super A233 both from King Industries.
Another preferred embodiment comprises dimeric, oligomeric or polymeric epoxy and oxetane functional groups. Such epoxy materials which result from the reaction of bisphenol-A (4,4′-isopropylidenediphenol) and epichlorohydrin, or by the reaction of bisphenol-A diglycidyl ether epoxies with another bisphenol-A monomers. Preferred epoxy monomers in the present invention involve Araldite LY-564, Araldite GY-6004, bisphenol-A diglycidyl ether epoxy, and poly[(phenylglycidyl ether)-co-formaldehyde] (Epoxy Novolac Resin, D.E.N. 438) from Dow Chemicals. A reactive epoxy diluents in preferred embodiment are from 4-vinylcyclohexene dioxide, 4-vinylcyclohexene oxide, Araldite RD-2, Cyracure UVR-6105 (3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane-carboxylate), and Cyracure UVR-6128. Oxetane diluents, monomers, and oligomers can be from Cyracure UVR-6000 (3-ethyl-3-(hydroxymethyl)oxetane) and OXT-121 (1,4-bis([(3-ethyl-3-oxetanylmethoxy)methyl]benzene, xylilene oxetane, n=1-3). Cyracure UVR-6000 is the preferred oxetane in this invention.
Another preferred embodiment comprises the addition of some stabilizers, such as stabilizers from Ciba Chemicals under the trade name of Irganox, well known to skilled in the art.

Example 4

Starting materials described in the above Examples were also employed in this example. Additionally, Araldite LY-564 was obtained from Huntsman Chemical Company. Cyracure UVR-6000, (3-ethyl-3-(hydroxymethyl)oxetane) and Cyracure UVR-6976 were obtained from The Dow Chemical Company. Nacure® Super XC-7231, ammonium antimonite was obtained from King Industries, Inc.
Araldite LY 564 had a viscosity around 1400 cP at 25° C. Araldite LY-564 was diluted with different amounts of Cyracure UVR 6000 to get a viscosity profile. The following table is a summary of the viscosity changes observed with respect to weight percent of Cyracure UVR 6000 added into Araldite LY-564.

Amount of Cyracure UVR 6000 η

(wt %) (cP, 25° C., 10 rpm, spindle = 40)

15.0 560

7.5 750

4.86 920

3.96 1025

Example 5

Araldite LY-564 was formulated with Cyracure UVR-6000 and Nacure® Super XC-7231 to test thermal cure profiles. Cyracure UVR 6000 was added based on the weight of Araldite LY 564. The added amount was 3.88 wt %. Nacure® Super XC-7231 was added based on the total weight of the formulation (0.78 wt %). The following table shows the overall weight percentages that are normalized to a 100% scale.

Component Amount (g) % wt/wt

Cyracure UVR 6000 0.1166 3.69

Araldite LY 564 3.0142 95.53

Nacure ® Super XC-7231 0.0245 0.78
The formulation was stirred overnight. Three sandwiched slides from microscope slides at 500 μm thickness and three vials containing 20 drops of the formulation were prepared. Samples were kept at 75° C. in a convection oven. Refractive index of the formulation was n_D ²⁵=1.5491 and the cured film after 5.5 hours had a refractive index of n_D ²⁵=1.5709 (Δ=0.022). Viscosity of the formulation was 1,078 cP at 25° C. (10 rpm, 41.2% torque, spindle=40). The cured film was hard and the slides exhibited excellent adhesion to the glass. The cured film was clear, colorless, exhibited high transmittance and was free from scattering. No wiggly lines (or alligator skin lines) were observed.

Example 6

Another formulation similar to Example 5 was prepared to test the repeatability and the shelf life of the formulation. The formulation details are given in the following table.

Component Amount (g) % wt/wt

Cyracure UVR 6000 0.2332 3.70

Araldite LY 564 6.0230 95.49

Nacure ® Super XC-7231 0.0512 0.81
Cyracure UVR 6000 was added based on the weight of Araldite LY 564. The added amount was 3.87 wt %. Nacure® Super XC-7231 was added based on the total weight of the formulation (0.82 wt %). The formulation was stirred overnight. Three sandwiched microscope slides at 500 μm thickness and three vials containing 20 drops of the formulation were prepared. The samples were kept at 75° C. in a convection oven. The refractive index of the formulation was n_D ²⁵=1.5493, z=22.9. Viscosity of the formulation was 1096 cP at 25° C. (10 rpm, 41.9% torque, spindle=40). The cured film was hard and the slides exhibited excellent adhesion to the glass. The cured film was clear, colorless, free from scattering and exhibited high transmittance. No wiggly lines (or alligator skin lines) were observed. Adhesion to glass was excellent after 5.5 h of curing at 75° C.
The viscosity and the refractive index of the formulation were measured after 6 days later and did not exhibit any change (η=1015 cP, 38.8% torque, 10 rpm, spindle=40, n_D ²⁵=1.5493, z=22.9). Further samples were taken and examined over a 3 month period. Viscosity and refractive index measurements yielded no significant changes. It proved that the initiator is a latent thermal initiator for cationic ring opening polymerization, CROP, and the formulation was stable at ambient temperatures.

Example 7

The formulation with Araldite LY 564, Cyracure UVR 6000, and Nacure® Super XC-7231 was prepared to test mid-range scalability (see ratio of components in the table below). A scaled up formulation was also used to get enough material for pull tests, shrinkage measurements, shelf life stability and spectacle lens assembly in sandwiched format from 1.6 index lens materials. Details of the formulation were tabulated in the table below. All ingredients were carefully weighed into a pre-washed 250 mL round-bottom flask that was equipped with a magnetic stirrer. The formulation contents were mixed by stirring for 20 h. The formulation was filtered through a Stericup filter (0.45 μm) under vacuum. The clear formulation was poured into pre-washed, dry, and argon purged amber bottles. The yield was 60.15 g (85.06%). The loss in the flask during transfer to the Stericup filter was 1.69 g (2.39%). The remaining mechanical loss occurred during filtration and in the Stericup filter. Four sandwiched microscope slides at 500 μm thickness were prepared and cured at 75° C. for 17 h. The adhesion to the glass substrate was excellent. It was impossible to release the cured film from the sandwiched configuration. Open face samples were prepared and cured at 75° C. for 17 h. Even the open faced films adhered to glass substrate very well. Meticulous measurements of refractive index were taken from the film. Some results were repeated by using a high index contact fluid. The film index measured at 25° C. was 1.5794. Viscosity and physical data are summarized in the following two tables. Adhesion to the glass substrates and 1.6 lens blanks was excellent.

Component Amount (g) % wt/wt

Cyracure UVR 6000 2.62 3.71

Araldite LY 564 67.49 95.43

Nacure ® Super XC-7231 0.61 0.86

Total 70.72



Viscosity	%
(cP, 25° C., Spindle = 40)	Torque	rpm	n_D ²⁵

1088	20.8	5	1.5492, z = 22.9
1096	41.9	10	1.5794 (Film)
1112	85.0	20	Δn = 0.030

Example 8

The formulation of example 7 passed the pull tests (adhesion>1200 psi) after 5.5 h and 18 h of curing. Adhesive and chunks failed during the pull tests but the formulation material did not show any sign of delamination from 1.6 lens material or failure of any kind. The total shrinkage was determined to be 3.0% (1.0% linear in each direction). It might be necessary to repeat the experiments with a larger mass samples to get more accurate picture of shrinkage. The liquid density was measured as 1.1480 g/mL at 23° C.

Example 9

Lens assemblies were formed from 1.6 index materials by sandwiching the formulation of Example 7 between two 1.6 index lens blanks set at 0.5 mm. The formulation was filled in to get a 0.5 mm thickness layer between the 2 lens blanks and it was cured at 75° C. for 17 h. The lenses were used in Example 8 for adhesion tests. Later, they were cut into half after the pull tests to determine the cap, film, and base thicknesses. In each case the film thickness was around 0.50 mm.

Layer Thicknesses

Lens # Cap Film Base

9425 0.95 0.54 7.27

9515 0.95 0.50 7.85

9258 0.88 0.57 7.79

Example 10

The formulation with Araldite LY 564, Cyracure UVR 6000, and Nacure® Super XC-7231 was scaled up to 700 g. Details of the formulation are tabulated in the table below. All ingredients were carefully weighed into a pre-washed 2 L round-bottom flask that was equipped with a magnetic stirrer. The formulation contents were mixed by stirring for 3 days at ambient temperature. The formulation was filtered through Stericup filter (0.45 μm) under vacuum to a one-liter amber bottle. The clear formulation was poured into pre-washed, dry, and argon purged amber bottles. The yield was 696.68 g (96.85%). The overall mechanical loss occurred during filtration and transfer was 3.15%. The formulation was repeatable and the shelf life was greater than 3 months under ambient conditions.

Component Amount (g) % wt/wt

Cyracure UVR 6000 26.64 3.71

Araldite LY 564 686.52 95.43

Nacure ® Super XC-7231 6.20 0.86

Total 719.36



Viscosity	%
(cP, 25° C., Spindle = 40)	Torque	rpm	n_D ²⁵

1020	19.5	5	1.5497, z = 22.9
1036	39.6	10
1045	79.9	20

Example 11

Another formulation was prepared similar to the above examples. Compositions are given in the table below. Prescription lenses from the formulations were prepared in sandwiched format at 0.5 mm thickness between 1.6 index lens blanks. The lenses were thermally cured for 17 h and grinded. The lenses were coated with an anti-reflective coating and a hard coat. Finally, the lenses were framed.

Component Amount (g) % wt/wt

Cyracure UVR 6000 5.56 3.71

Araldite LY 564 143.15 95.43

Nacure ® Super XC-7231 1.29 0.86

Total 150.00



Viscosity	%
(cP, 25° C., Spindle = 40)	Torque	rpm	n_D ²⁵

1110	21.2	5	1.5494
1120	42.9	10
1135	86.8	20

Example 12

The formulation from Example 11 was reformulated by taking 10.00 g aliquots. Sulfonium based, Cyracure UVR-6976, a cationic photo initiator was added in amounts of 0.25 and 0.5 wt % to each 10.00 g aliquot, respectively. Sample slides by sandwiching 0.5 mm thick liquid between 3M ceramic tapes were constructed from microscope slides. Slides were thermally cured at 75° C. for 0, 1, 2, 3, 4, 5, 6, and 17 h. A logo was attempted to be written photochemically on the cured slides with a spatially filtered tripled YAG laser operating at 25 kHz with 8 nanoseconds pulses with an average power of 23 mW at 355 nm. Three laser passes were carried on to write the logo. The slides were then examined. Logo writing was successful on all slides except the 17 h cured slide. It was clear form the experiments that 17 h cure did not leave any residual monomers to provide enough dynamic range for logo writing. The polymerization was mostly carried out via thermal latent acid initiator. Sulfonium photo acid generators were stable under the experimental conditions and they did not release acid. Separate control experiments with only Araldite LY-564/Cyracure UVR-6000 and Araldite LY-564/Cyracure UVR-6000/Cyracure UVR-6976 were prepared and kept at 75° C. for 17 h. There was no apparent cure for the samples. The slides were put in the oven at 75° C. for additional 2 h to diffuse the remaining monomers and slides were further examined. Logo image was enhanced on the slides except for the Oh cured slide which showed some image washing. Further, slides were kept in the oven for additional 15-16 h except for the 17 h cured slide. The logo image fainted but was still visible in all slides except Oh cured slide. The best results were taken from the samples having 0.5 wt % photoacid generator and an initial cure time of about 4 to 6 h. Six hour cure was the preferred time for logo writing.
Five more slides were prepared and thermally cured at 75° C. for 6 h. Logo writing was attempted after 3 days and 7 days. A logo was successfully written after 3 and 7 days indicating that activating the thermal cationic initiator for 6 h at 75° C. did not completely consume the available dynamic range for the logo writing. The written logo showed enhanced characteristics after two additional hours at 75° C. Keeping the slides at 75° C. for an additional 17 h did show some fading but the quality was still excellent and logo was visible. The number of logo writing passes is not limited to three passes and can be modified in any number to adjust desired image writing and post image fixing properties.

Claims

1. A method of making an optical element by forming a polymer layer employing a thermally initiated cationic ring opening polymerization reaction which comprises:

a. mixing one or more monomers and a thermal initiator,

b. forming a layer of the mixture of (a) and

c. heating the layer to cure it.

2. The method of claim 1 wherein the monomer is an epoxy, an oxetane or mixtures thereof.

3. The method of claim 1 further comprising adding a photoinitiator to the mixture of (a).

4. The method of claim 3 wherein the photoinitiator is an arylsulfonium, alkylsulfonium, or aryliodonium photo acid generator.

5. The method of claim 1 wherein the thermal initiator is a latent thermal cationic acid generator.

6. The method of claim 5 wherein the latent thermal cationic acid generator is ammonium hexafluoroantimonate.

7. A method of making an optical element by forming a polymer layer employing a thermally initiated cationic ring opening polymerization reaction which comprises:

a. mixing one or more monomers, a latent thermal cationic acid generator and a cationic photoinitiator;

b. forming a layer of the mixture of (a);

c. heating the layer to partially cure it;

d. irradiating the layer to form a variable index of refraction profile in the layer; and

e. heating the layer to fully cure all of the unreacted monomers.

8. The method of claim 7 wherein the monomer is an epoxy, an oxetane or mixtures thereof.

9. The method of claim 7 wherein the photoinitiator is an arylsulfonium, alkylsulfonium, or aryliodonium photo acid generator.

10. The method of claim 7 wherein the thermal initiator is a latent thermal cationic acid generator.

11. The method of claim 10 wherein the latent thermal cationic acid generator is ammonium hexafluoroantimonate.

12. A method of making an optical element having a variable index of refraction profile which comprises:

a. forming a layer comprising a mixture of two or more monomers that have differing initial refractive indices and differing cured refractive indices; and

b. curing specific monomers at specific points across the layer to create a pattern of refractive index that has a Δn of up to 0.30.

13. The method of claim 12 wherein two or more of the following monomers are present in said mixture of (a):

R(SH)_n

R(X)_nand

R(Y)_n

14. A method of making a lens material comprising:

a. making a mold of a desired shape,

b. melting a mixture of monomers selected from the group consisting of R(SH)_n, R(X)_nand R(Y)_nand

c. curing the monomers with heat

15. The method of claim 14 wherein the lens material is a slab (sheet).

16. The method of claim 14 wherein the lens material is a lens blank.

17. A formulation to make an optical element which comprises:

a. one or more monomers selected from the group consisting of epoxy monomers, oxetane monomers and mixtures thereof and

b. a thermal initiator.

18. The formulation of claim 17 further comprising a photoinitiator.

19. The formulation of claim 18 wherein the thermal initiator is a latent thermal cationic acid generator and the photoinitiator is an arylsulfonium, alkylsulfonium, or aryliodonium photo acid generator.

20. The formulation of claim 19 wherein the latent thermal cationic acid generator is ammonium hexafluoroantimonate.