Ophthalmic lens comprising an encapsulated light-absorbing additive

Abstract

The present invention relates to an ophthalmic lens which efficiently absorbs light rays comprising a composition derived from a monomer or oligomer, a catalyst, at least one light-absorbing additive contained in nanoparticles which are dispersed in said monomer or oligomer.

Claims

1. An ophthalmic lens comprising a composite substrate comprising: a matrix obtained by polymerization of at least one allyl or non-allyl monomer or oligomer in presence of a catalyst for initiating the polymerization of said monomer or oligomer; and nanoparticles containing at least one light absorbing additive, said nanoparticles being such that active reactants involved in the polymerization of the matrix are not able to diffuse to the internal part of the nanoparticles and said nanoparticles being dispersed in said matrix wherein: the nanoparticles encapsulate a light-absorbing additive; and the light-absorbing additive is not a photochromic dye.

2. The ophthalmic lens according to claim 1, wherein the matrix is chosen from a thermoplastic resin or a thermosetting resin and combinations thereof.

3. The ophthalmic lens according to claim 1, wherein the light-absorbing additive is chosen from a colorant, a colorless light-absorbing additive or mixtures thereof.

4. The ophthalmic lens according to claim 1, wherein the molar absorption coefficient of the light-absorbing additive is higher than 5000.

5. The ophthalmic lens according to claim 1 wherein the nanoparticles have a homogeneous composition from inside to outside in which the light-absorbing additive is uniformly distributed.

6. The ophthalmic lens according to claim 1, wherein the nanoparticles have a core containing the light-absorbing additive and a shell surrounding the core.

7. The ophthalmic lens according to claim 1, wherein the nanoparticles present an outer surface which does not comprise any organic compound.

8. The ophthalmic lens according to claim 1, wherein the nanoparticles comprise at least one mineral oxide.

9. The ophthalmic lens according to claim 1, wherein the refractive index of the nanoparticles is from 1.47 to 1.74, as measured according to the ISO 489:1999.

10. The ophthalmic lens according to claim 1, wherein the size of the nanoparticles is from 1 nm to 10 μm, as measured according to the Dynamic Light Scattering method.

11. The ophthalmic lens according to claim 1, wherein the amount of light-absorbing additive in the nanoparticles is from 0.0001 to 90 wt % based on the total weight of the nanoparticles.

12. The ophthalmic lens according to claim 1, wherein the amount of nanoparticles in the polymer matrix is from 0.01 to 2 wt % based on the weight of the polymer matrix.

13. A process for preparing the ophthalmic lens according to claim 1, comprising the steps of: a) providing monomers or oligomers from which the matrix can be prepared; b) preparing nanoparticles encapsulating a light-absorbing additive either in the form of a powder which is dispersible within the monomers or oligomers or in the form of a dispersion of nanoparticles in a liquid which is dispersible within the monomers or oligomers; c) providing a catalyst for initiating the polymerization of said monomers or oligomers; d) mixing the monomers or oligomers, the nanoparticles and the catalyst so as to obtain a polymerizable liquid composition in which nanoparticles are dispersed; and e) curing the polymerizable liquid composition.

14. The process according to claim 13, further comprising depositing the polymerizable liquid composition on a substrate prior to curing the polymerizable liquid composition.

Description

FIGURES

(1) FIG. 1 is a graph of transmittance as a function of wavelength for a composition comprising a light-absorbing additive (OMNISTAB™ 47, wavelength of maximum absorption at 424 nm) in polymer-based nanoparticles prior to polymerization (dotted line) and after polymerization (solid line).

(2) FIG. 2 is a graph of transmittance as a function of wavelength for a lens with a non-encapsulated light-absorbing additive (dotted line) and a light-absorbing additive encapsulated in polymer-based nanoparticles (solid line).

MEASURING METHODS

(3) The following measures are carried out on a lens that is 2 mm thick in its center and that has been cleaned with isopropyl alcohol.

(4) The average (or mean) light transmittance over 420-450 nm range (TB %) is computed from transmittance curve measured according to ISO 8980-3-2003.

(5) The size of the nanoparticles is measured by standard Dynamic Light Scattering method. The technique measures the time-dependent fluctuations in the intensity of scattered light from a suspension of nanoparticles undergoing random Brownian motion. Analysis of these intensity fluctuations allows for the determination of the diffusion coefficients, which, using the Stokes-Einstein relationship can be expressed as the particle size.

(6) Haze value is measured by light transmission measurement using the Haze-Guard Plus© haze meter from BYK-Gardner (a color difference meter) according to the method of ASTM D1003-00. All references to “haze” values in this application are by this standard. The instrument is first calibrated according to the manufacturer's instructions. Next, the sample is placed on the transmission light beam of the pre-calibrated meter and the haze value is recorded from three different specimen locations and averaged.

(7) Colorimetric coefficients of the lenses of the invention are measured according to the international colorimetric system CIE L*a*b*, i.e. calculated between 380 and 780 nm, taking the standard illuminant D 65 at angle of incidence 150 and the observer into account (angle of 10°).

(8) Materials

(9) In the examples, the following compounds are used:

(10) TABLE-US-00001 Component CAS number Function CR-39 ® 142-22-3 allyl monomer CR-39E ® Proprietary allyl monomer (as disclosed in U.S. Pat. No. 7,214,754) IPP 105-64-6 catalyst SK-1.60 Optical Resin Proprietary Composition comprising: Monomer epoxy acrylate (Supplier Jiangsu styrene Shikexincai Co., Ltd.) Corresponding to Acrylic monomer. 2,2′-Azodi- 13472-08-7 catalyst (2-methylbutyronitrile) 2,5(or 2,6)-bis(iso- 74091-64-8 Isocyanate monomer cyanatomethyl)- Bicyclo[2.2.1]heptane Pentaerythritol tetrakis 7575-23-7 Thiol monomer mercaptopropionate 4-Mercaptomethyl-3,6- 131538-00-6 Thiol monomer dithia-1,8-octanedithiol Dimethyl Chloride (DMC) 753-73-1 catalyst methyl methacrylate 80-62-6 monomer to prepare polymer-based nanoparticles ethylene glycol 97-90-5 reticulating agent to prepare dimethacrylate polymer-based nanoparticles 2,2′-Azobis(2,4- 4419-11-8 catalyst dimethylvaleronitrile) (AIVN) tetraethyl orthosilicate 78-10-4 precursor for mineral-based (TEOS) nanoparticles tetrabutyl orthotitanate 5593-70-4 precursor for high index (TBOT) mineral-based nanoparticles sodium dodecylsulfate 151-21-3 ionic surfactant (SDS) Triton X-100 9002-93-1 surfactant Zelec-UN (Supplier Mitsui Proprietary Demolding agent Chemical)

Example 1: Preparation of Polymer-Based Nanoparticles Containing a Light-Absorbing Additive by Miniemulsion Polymerization

(11) A monomer blend (5 g) is prepared from methyl methacrylate and ethylene glycol dimethacrylate in a weight ratio of 50:50, and OMNISTAB™47 (10 mg, available from Deltachem Co. Ltd.) is dissolved in this monomer blend. This blend is added dropwise to 50 ml of an aqueous solution containing SDS (0.5 g) and AIVN (0.05 g) at 80° C. under a nitrogen atmosphere. After completion of the monomer blend addition, the mixture is then further mixed for additional 2 h at 80° C., then centrifuged, washed with ethanol, and dried. The nanoparticles have a size in the range of 200 nm to 1000 nm and a refractive index of 1.5.

(12) The nanoparticles are dispersed in CR39® (12.5 weight % nanoparticles in monomer) to prepare a masterbatch (Master 1).

Example 2: Preparation of Mineral-Based Nanoparticles Containing a Light-Absorbing Additive by Reverse Microemulsion, with Refractive Index Around 1.47

(13) Ex. 2a: A mixture of cyclohexane (7.5 ml), n-hexanol (1.8 ml), Triton X-100 (1.5 g), OMNISTAB™47 (40 mg, available from Deltachem Co; Ltd), TEOS (0.1 ml) and ammonium hydroxide 30% (0.06 ml) are mixed for 24 h. Then, acetone is added and the particles are collected by centrifugation, washed with ethanol and dried. The nanoparticles have a monodisperse size centered on 100 nm and a refractive index corresponding to precipitated silica, around 1.47.

(14) The nanoparticles are dispersed in CR-39® (12.5 weight % nanoparticles in monomer) to prepare a masterbatch (Master 2a).

(15) Ex. 2b: 7.56 g of Triton X-100, 5.86 g hexan-1-ol, 23.46 g cyclohexane, 1.6 ml deionized water, 0.32 ml of methylene blue solution (CAS: 61-73-4, 1% weight solution in water) which is the light-absorbing additive, 0.4 ml of TEOS, and 0.24 ml of 30% ammonium hydroxide solution in water are mixed and stirred at room temperature for 24 h.

(16) After 24 h, one volume of acetone (around 50 ml) is added to the obtained solution, and the particles are collected by centrifugation, washed with acetone or water, dried overnight at room temperature, and annealed in an oven at 80° C. for 3 hours.

(17) 0.2 g of the obtained dried mineral nanoparticles are then redispersed under magnetic stirring in approx. 20 ml acetone and zirconium beads having size of 1 mm as grinding agents. The mixture is finally filtered to remove zirconium beads. 99.8 g of CR-39® is then added and the acetone is stripped out under vacuum so as to obtain a masterbatch (Master 2b).

(18) Ex. 2c: 7.56 g of Triton X-100, 30 ml of hexan-1-ol, 7.2 ml of cyclohexane, 1.6 ml deionized water, 0.32 ml of methylene blue solution (CAS: 61-73-4, 1% weight solution in water) which is the light-absorbing additive, 0.4 ml of TEOS, and 0.24 ml of 30% ammonium hydroxide solution in water are mixed and stirred at room temperature for 24 h.

(19) After 24 h, one volume of acetone (around 50 ml) is added to the obtained solution, and the particles are collected by centrifugation, washed with acetone or water, dried overnight at room temperature. The nanoparticles have a monodisperse size of 100 nm and a refractive index corresponding to precipitated silica, around 1.47.

(20) Nanoparticles are dispersed in CR-39® as in example 2b, to prepare a masterbatch (Master 2c).

(21) Ex. 2d: Ex. 2c was reproduced (Master 2d), except that 1.76 ml of deionized water was used instead of 1.6 ml and 7.4 g of Triton X-100 instead of 7.54 g. The nanoparticles have a monodisperse size of 80 nm.

(22) Ex. 2e: Ex. 2c was reproduced (Master 2e), except that 2.16 ml of deionized water was used instead of 1.6 ml and 7 g of Triton X-100 instead of 7.54 g. The nanoparticles have a monodisperse size of 50 nm.

(23) Examples 2c to 2e show that the ratio between deionized water and Triton X-100 defines the final size of nanoparticles: the higher the ratio, the smaller the nanoparticles.

(24) Ex. 2f: Ex. 2c was reproduced (Master 2f), except that 1.44 ml of deionized water was used instead of 1.6 ml and 7 g of Triton X-100 instead of 7.54 g. Further, 0.16 ml of 5,10,15,20-Tetrakis(4-sulfonatophenyl)-porphine-Cu(II) (TSPP-Cu(II)) solution (0.01M in deionized water) was added. The nanoparticles have a monodisperse size of 100 nm.

(25) Other light absorbing agents have been used with the same preparation procedure, as summarized in the table A below.

(26) TABLE-US-00002 TABLE A Color Index number (C.I.) Molecule 60730 Acid Violet 43 42090 Acid Blue 9 42051 Acid Blue 3 (Patent Blue V) 74180 Solvent Blue 38 (for microscopy Luxol ® Fast Blue MBSN) 20470 Acid Black 1 42045 Acid Blue 1 TSPP-Cu(II)

Example 3: Preparation of Mineral-Based Nanoparticles Containing a Light-Absorbing Additive by Reverse Microemulsion, with Refractive Index Higher than 1.5

(27) Ex. 3a: Nanoparticles obtained in example 2c are introduced in an aqueous solution of 36.5% in weight of tetrabutyl orthotitanate (TBOT).

(28) 1 g of nanoparticle obtained in example 2b is dispersed in 25 ml of 20 vol water: 1 vol ethanol mixture. Then 1.85 ml of HCl (37% weight solution in water) is added in the mixture. The reaction is stirred by magnetic bar for 15 min. After that, 9.1 g of tetrabutyl orthotitanate (TBOT) is added dropwise and mixture is continuously stirred for 3 h at room temperature.

(29) A thin layer of titania is deposited on the silica based nanoparticles, yielding core shell nanoparticles. These nanoparticles are washed with ethanol, dried at room temperature then annealed at 180° C. for 2 h and have a monodisperse size of 100 nm with a refractive index around 1.54.

(30) A masterbatch is prepared (Master 3a) as for example 2b, but using SK-1.60 Optical Resin Monomer as an acrylic monomer instead of CR-39®.

(31) Ex. 3b: Ex. 3a is reproduced, except that 15.0 g of TBOT is added. Nanoparticles have a monodisperse size of 100 nm with a refractive index higher than 1.55.

(32) A masterbatch is prepared (Master 3b) as for example 2b, but using 4-Mercaptomethyl-3,6-dithia-1,8-octanedithiol instead of CR-39®.

Example 4: Preparation of Mineral-Based Nanoparticles Containing a Light-Absorbing Additive by Stöber Process, with Refractive Index Around 1.47

(33) 384 mL of methanol is added in 1000 ml bottle. Then, 96 ml of NH.sub.4OH (30% weight solution in water) and 6.4 mL of methylene blue (CAS: 61-73-4, 2% weight solution in deionized water) are added. The mixture is stirred (magnetic stirring) at 400 rpm for 10 min. After that, 3.2 ml of TEOS is added dropwise and stirred at 800 rpm for 2 h.

(34) After reaction is complete, particle size is checked by Dynamic Light Scattering. The average particle size is around 200-230 nm (mono-disperse).

(35) Mixture is transferred to round bottle flask for evaporating 1 h in order to reduce the volume of methanol from 500 to 100 ml, then, centrifuged at 4000 rpm for 45 min. Supernatant is removed and nanoparticles are retrieved as concentrated dispersion in methanol.

(36) Mixture is then cleaned two times with the following procedure: 50 ml of methanol is added with sonication to re-disperse particle. Nanoparticle are collected by centrifugation at 4000 rpm for 30 min.

(37) Nanoparticles are air dried at ambient temperature overnight, then grinded in an agathe mortar. Then nanoparticles are annealed at 180° C. for 2 hours. 0.3 g of nanoparticle is mixed with 99.7 g of CR-39® monomer in 250 ml bottle. The master-batch is sonicated for 30 min. Centrifugation at 4000 rpm for 30 min is applied to remove the agglomerated particle. The supernatant is collected to obtain a master-batch (Master 4).

Example 5: Preparation of Mineral-Based Nanoparticles Containing a Light-Absorbing Additive by Stöber Process, with Refractive Index Higher than 1.5

(38) Nanoparticles obtained in example 4 are introduced in an aqueous solution of 36.5% in weight of tetrabutyl orthotitanate (TBOT).

(39) 1 g of nanoparticle obtained in example 4 is dispersed in 25 ml of 20 vol water:1 vol ethanol mixture. Then 1.85 ml of HCl (37% weight solution in water) is added in the mixture. The reaction is stirred by magnetic bar for 15 min. After that, 9.1 g of tetrabutyl orthotitanate (TBOT) is added dropwise and mixture is continuously stirred for 3 h at room temperature.

(40) A thin layer of titania is deposited on the silica based nanoparticles, yielding core shell nanoparticles. These nanoparticles are washed with ethanol, dried at room temperature then annealed at 180° C. for 2 h and have a monodisperse size of 200-230 nm with a refractive index around 1.54.

(41) A masterbatch is prepared (Master 5) as for example 4, but using but using SK-1.60 Optical Resin Monomer as an acrylic monomer instead of CR-39®.

Example 6: Preparation of a Ophthalmic Lenses According to the Invention

(42) Ex. 6a:

(43) TABLE-US-00003 TABLE 1 Material Parts by weight CR39 ® 95.00 CR39E ® 2.00 Master 1 or 2a-f or 4 2.00 IPP 2.40

(44) The monomer blend is manufactured by weighing and mixing the ingredients of table 1 in a beaker at room temperature. CR39® and CR39E® are first mixed. Once homogeneous, nanoparticles in masterbatch are added then the beaker content is mixed again until full dispersion. Finally, IPP is added and the mixture is stirred thoroughly, then degassed and filtered.

(45) A 71 mm diameter glass bi-plano mold was then filled with the composition using a syringe and the polymerization was carried out in a regulated electronic oven in which the temperature was gradually increased from 45° C. to 85° C. in 15 hours then kept constant at 85° C. for 5 hours. The mold was then disassembled and the resulting lens had a 2 mm thickness in its center.

(46) As shown in FIG. 1, the transmission spectrum of the composition comprising Master 1 before polymerization and the transmission spectrum of the lens after polymerization show the same transmittance reduction for the maximum absorption wavelength of the light-absorbing additive (424 nm). As such, in the ophthalmic lens according to the present invention the dye has not been degraded by the IPP catalyst during polymerization. Differences in both spectra outside the absorption domain of the light-absorbing additive are obviously linked to the chemical transformation occurring during polymerization (catalyst dissociation, reaction of unsaturated groups . . . ).

(47) As shown in FIG. 2, the resulting ophthalmic lens has an average transmittance TB % of 77% in the range of 420 nm to 450 nm. In comparison, the same ophthalmic lens comprising non-encapsulated dye has an average transmittance TB % of 91%. As such, the ophthalmic lens comprising an encapsulated dye according to the present invention exhibits a better absorption of blue light than the corresponding ophthalmic lens comprising a non-encapsulated dye.

(48) The effects of methylene blue as the light absorbing additive, on haze (light diffusion), particle size and residual color of the lens (as measured by b* according to CIE Lab model) were evaluated with various nanoparticles. Conditions of Example 2b are reproduced, except that the concentration of methylene blue aqueous solution is varied between 0.4% and 1% by increments of 0.2%, yielding nanoparticles with different concentrations of methylene blue.

(49) The increase of methylene blue concentration in nanoparticles showed a positive trend on haze, because less particles were required to obtain the same colouring effect. With particles obtained with 1% methylene blue solution, average transmittance TB % is decreased from 0.5 to 0.3 compared to the particles obtained with 0.4% methylene blue solution, without degrading haze performance.

(50) Increasing the methylene blue concentration also led to an increase in particle size: at 0.4%, the measured particle size was around 80 nm, whereas it was around 90 nm at 0.6%, and 95 nm at both 0.8% and 1%.

(51) Measurements also showed that the haze generated by deionized water washed nanoparticles is around 20-40% lower than that of acetone washed nanoparticles, for a similar residual color (measured by b* reduction in Lab system).

(52) Ex. 6b:

(53) TABLE-US-00004 TABLE 2 Material Parts by weight SK-1.60 Optical Resin Monomer 95.78 Zelec UN 0.1 Master 3a or 5 4.00 2,2′-Azodi-(2-methylbutyronitrile) 0.12

(54) The monomer blend is manufactured by weighing and mixing the ingredients of table 2 in a beaker at room temperature. Once homogeneous, mixture is degassed and filtered.

(55) A bi-plano mold with 71 mm of diameter is filled with monomer mixture by using syringe.

(56) The polymerization is conducted in a regulated electronic oven in which the temperature is gradually increased from 25° C. to 95° C. in 16.5 hours then kept constant at 95° C. for 2 hours. The mold is then disassembled and the clear lens with a 2 mm center thickness is obtained.

(57) Ex. 6c:

(58) TABLE-US-00005 TABLE 3 Material Parts by weight 2,5(or 2,6)-bis(iso-cyanatomethyl)-Bicyclo[2.2.1]heptane 50.54 Pentaerythritol tetrakis mercaptopropionate 23.87 4-Mercaptomethyl-3,6-dithia-1,8-octanedithiol 23.47 Master 3b 4.00 Dimethyl Chloride (DMC) 0.04 Zelec-UN 0.07

(59) The monomer blend is manufactured by weighing and mixing the ingredients of table 3 in the following manner.

(60) 2, 5(or 2, 6)-bis(iso-cyanatomethyl)-Bicyclo[2.2.1]heptane, DMC, and Zelec UN® are first mixed at room temperature under vacuum for 1 h. Once homogeneous, the mixture is cooled down to 5° C. then N.sub.2 gas is transferred inside bottle to release vacuum. After that, Pentaerythritol tetrakis mercaptopropionate, 4-Mercaptomethyl-3,6-dithia-1,8-octanedithiol and Master 3b are added then the mixture is stirred until full dispersion under vacuum at 5° C. The vacuum is released by N.sub.2 replacement.

(61) A bi-plano mold with 71 mm of diameter is filled with monomer mixture by using syringe. The polymerization cycle starts at 15° C. and then temperature is gradually increased to 130° C. in 16 hours and kept constant for 3 h. The mold is then disassembled and the clear lens with a 2 mm center thickness is obtained.