OPTICAL MATERIAL COMPRISING A RED-SHIFTED BENZOTRIAZOLE UV ABSORBER

Abstract

The present invention relates to an eyeglass lens comprising a substrate made of an optical material comprising a polymer matrix and at least one 2-(2-hydroxy-5-R.sup.1-phenyl)benzotriazole, in which R.sup.1 is a resonant group, the optical transmittance through a 2 mm thick layer of said optical material being lower than 1% for each light wavelength ranging from 280 to 405 nm. This eyeglass lens protects from phototoxic blue light and UV light.

Claims

1.-15. (canceled)

16. An eyeglass lens comprising a substrate made of an optical material comprising a polymer matrix and at least one 2-(2-hydroxy-5-R.sup.1-phenyl)benzotriazole, in which R.sup.1 is a resonant group, wherein optical transmittance through a 2 mm thick layer of said optical material is lower than 1% for each light wavelength ranging from 280 to 405 nm.

17. The eyeglass lens of claim 16, wherein said at least one 2-(2-hydroxy-5-R.sup.1-phenyl)benzotriazole does not comprise any polymerizable group selected from allylic, acrylic and methacrylic moieties.

18. The eyeglass lens of claim 16, wherein said benzotriazole is a compound of formula (I): ##STR00007## in which R.sup.1 is a resonant group, the R.sup.2 groups are identical or different monovalent groups, n is an integer equal to 0 or 1, the R.sup.3 groups are identical or different monovalent groups, m is an integer ranging from 0 to 2.

19. The eyeglass lens of claim 18, wherein m=0.

20. The eyeglass lens of claim 16, wherein R.sup.1 is selected from the groups amino, hydroxyl, alkoxy, aryloxy, alkylamino, arylamino, dialkylamino, diarylamino, (aryl)(alkyl)amino, formamido, alkylamido, arylamido, formyloxy, alkylcarboxy, arylcarboxy, alkylimino, and arylimino.

21. The eyeglass lens of claim 20, wherein R.sup.1 is selected from the groups amino, hydroxyl, alkoxy, aryloxy, alkylamino, arylamino, dialkylamino, diarylamino, and (aryl)(alkyl)amino.

22. The eyeglass lens of claim 16, wherein the R.sup.2 and R.sup.3 groups are independently selected from a hydrogen atom and linear or branched, substituted or unsubstituted hydrocarbon groups comprising from 1 to 6 carbon atoms.

23. The eyeglass lens of claim 16, wherein 2-(2-hydroxy-5-R.sup.1-phenyl)benzotriazole, in which R.sup.1 is a resonant group, are present in an amount ranging from 0.05 to 3.0% by weight relative to the total weight of the substrate.

24. The eyeglass lens of claim 16, wherein the polymer matrix comprises at least one of a polyurethane, polythiourethane, polyepisulfide, polymer obtained from a polyol allyl carbonate, polycarbonate, or poly(meth)acrylate.

25. The eyeglass lens of claim 24, wherein the polymer matrix comprises at least one polymer obtained from diethylene glycol bis(allyl carbonate) or ethylene glycol bis(allyl carbonate).

26. The eyeglass lens of claim 24, wherein the polymer matrix comprises at least one polymer obtained from copolymerization of at least one polyisocyanate and at least one polythiol or from copolymerization of at least one polyepisulfide and at least one polythiol.

27. The eyeglass lens of claim 16, wherein the optical transmittance through a 2 mm thick layer of said optical material is lower than 1% for each light wavelength ranging from 280 to 410 nm.

28. A method for preparing an eyeglass lens of claim 16, comprising: obtaining a polymerizable composition comprising at least one 2-(2-hydroxy-5-R.sup.1-phenyl)benzotriazole, in which R.sup.1 is a resonant group, and at least one polymerizable compound; and curing said polymerizable composition so as to form a substrate made of an optical material comprising a polymer matrix and said at least one 2-(2-hydroxy-5-R.sup.1-phenyl)benzotriazole; wherein the optical transmittance through a 2 mm thick layer of said optical material is lower than 1% for each light wavelength ranging from 280 to 405 nm.

29. The method of claim 28, wherein said at least one polymerizable compound is selected from polyol allyl carbonates, polythiols, episulfides, polyisocyanates, polyisothiocyanates and (meth)acrylates.

30. The method of claim 29, wherein the polymer matrix comprises at least one polymer obtained from diethylene glycol bis(allyl carbonate), ethylene glycol bis(allyl carbonate), from at least one polyisocyanate and at least one polythiol or from at least one polyepisulfide and at least one polythiol.

Description

EXAMPLES

1. Chemicals Used

[0098] Optical materials were prepared from: [0099] a composition A comprising two polymerizable monomers, diethylene glycol bis(allyl carbonate) (CR-39, CAS No. 142-22-3) and tetraallyl urethane (CR-39E, available from PPG industries), a benzotriazole compound as an UV and optionally blue light absorber, and di-isopropylperoxycarbonate as a catalyst (CAS No. 105-64-6), or [0100] a composition B comprising three polymerizable monomers: 2,5(or 2,6)-bis(isocyanatomethyl)bicyclo-[2.2.1]-heptane, also known as bisisocyanatonorbonane (ISO, CAS No. 74091-64-8), pentaerythritol tetrakis (3-mercaptopropionate) (THIOL1, CAS No. 7575-23-7), and 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane (THIOL2, CAS No. 131538-00-6), a benzotriazole compound as an UV and optionally blue light absorber, Diaresin blue J as a bluing agent (BA, CAS No. 86090-40-6), and dimethyltin dichloride as a catalyst (CAS No. 753-73-1).

[0101] The benzotriazole compounds according to the invention used in the examples were 2-(2-hydroxy-5-methoxyphenyl)benzotriazole (formula IV), 2-(2-hydroxy-5-butoxyphenyl)benzotriazole (formula V), and 2-(2-hydroxy-5-amino phenyl)benzotriazole (formula VI). The structures of these compounds are reminded hereunder:

##STR00004##

[0102] The following comparative benzotriazole compounds were used: Seesorb 703 (2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole, CAS No. 3896-11-5, formula VII), Tinuvin Carboprotect (this compound does not fall within the scope of the present invention), and Seesorb 709 (2-(2-hydroxy-5-tert-octylphenyl) benzotriazole, CAS No. 52188-76-8, formula VIII). Compounds VII and VIII are devoid of resonant group in position 5 of the 2-hydroxyphenyl ring. The structures of Seesorb 703 (VII) and of Seesorb 709 (VIII) are reminded hereunder:

##STR00005##

2. Synthesis of 2-(2-hydroxy-5-R.SUP.1.-phenyl)benzotriazoles (R.SUP.1 .being a resonant group)

a) Synthesis of 2-(2-hydroxy-5-methoxyphenyl)benzotriazole

[0103] Step A: Diazonium Salt Preparation

[0104] 6.91 g (0.05 mol, 1 eq) of o-nitroaniline was crushed and transferred in a 250 mL bottle, followed by 30 mL of hydrochloric acid 37%. The mixture was stirred vigorously, and sonication may be used if needed to disperse remaining sediments to enable a homogeneous mixture. The pale tan to yellow opaque suspension was cooled in an ice bath. When the temperature reached 0-5 C., addition of NaNO.sub.2 solution (prepared from 3.61 g of NaNO.sub.20.052 mol, 1.05 eqin 10 g distillated water) was started in the stirred chlorhydrate suspension. During addition, the temperature must not exceed 5 C., and should ideally be maintained around 0 C. The diazonium salt solution was filtered on a glass Buchner using cold water and isolated in a pre-cooled filtering flask.

[0105] Step B: o-nitrophenylazo Intermediate Preparation

[0106] 2 g of NaOH were weighed in a beaker, followed by 150 mL of water (a few mL of water were added first to quickly dissolve NaOH), 15 g of Na.sub.2CO.sub.3 and 6.21 g of p-methoxyphenol (0.05 mol, 1 eq). The solution was stirred until full dissolution. It was then cooled in an ice bath to 5 C. The diazonium salt solution prepared in step A was slowly added (over 30 min) under mechanical stirring, keeping the temperature below 5 C. A brick-red solid appeared, and the suspension became viscous. The stirring speed was increased to ensure fast dilution of the diazonium salt solution. Once all the diazonium salt was added, the mixture was further stirred for 30 min below 5 C., then filtered under vacuum. The cake was washed with ice cold water until the filtrate was neutral, and dried at 80 C.

[0107] Step C: Cyclization of the o-nitrophenylazo Intermediate

[0108] 7.8 g of NaOH and 115 mL of distilled water were introduced in a two-neck 250 mL round bottom flask fitted with a dropping funned and a condenser. 8.19 g (0.03 mol) of the azo intermediate prepared in step B was added and stirred until dissolution. The dropping funnel was charged with a solution prepared from 14.34 g (0.082 mol, 2.75 eq) of sodium dithionite in 60 g of water. The solution was added dropwise over one hour under vigorous magnetic stirring. A slightly exothermic reaction occurred, and the mixture became dark green at mid addition. Once all the dithionite solution was added, the mixture was stirred at room temperature for one hour, then refluxed for one additional hour. The solution was filtered on a glass Buchner while still warm, then transferred in a 250 mL beaker. Under mechanical mixing, c.a. 4 mL of 30% hydrochloric acid were added portionwise, until pH 7-8 was reached. The suspension was filtered and the porous cake was washed with cold water. The moist cake was triturated in a small amount of acetone, filtered and dried. The material was recrystallized in boiling methanol. Yellow needles were obtained, having a melting point of 124 C. The structure was confirmed by IR and NMR.

b) Synthesis of 2-(2-hydroxy-5-aminophenyl)benzotriazole

[0109] This compound was obtained by using essentially the same protocol as above, replacing the p-methoxyphenol by 4-acetamidophenol, maintaining reflux for 4 h during the reductive cyclization step to ensure total deacetylation of the amino group, and by recrystallizing the crude product in an ethanol/water 1/1 V/V mixture. A yellow powder was obtained, having a melting point of 185 C. The structure was confirmed by IR.

c) Synthesis of 2-(2-hydroxy-5-butoxyphenyl)benzotriazole

[0110] This compound was obtained by using essentially the same protocol as above, replacing the p-methoxyphenol by 4-butoxyphenol. The structure was confirmed by IR and NMR.

[0111] The reaction scheme allowing the preparation of various 2-(2-hydroxy-5-R.sup.1-phenyl)benzotriazoles is shown hereunder:

##STR00006##

3. Manufacture of Lenses by Casting

[0112] Convex and concave glass plano molds having 71 mm diameter were assembled by using typing process. A center thickness adjustment was made to obtain lenses with 2 mm center thickness.

[0113] The formulations of the examples and comparative examples were prepared in small batch size by using a beaker with a glass tube for nitrogen intake and a vacuum connection.

[0114] For composition A, the CR-39E monomer was first added (2 parts by weight), followed by the CR-39 monomer (100X parts by weight). Then the benzotriazole absorber was added (X parts by weight, X ranging from 0.25 to 1.0), and the beaker content was mixed until full dissolution. The di-isopropylperoxycarbonate catalyst was added (2.92 parts by weight) and the mixture was stirred thoroughly, then degassed and filtered.

[0115] The assembled molds were filled with the final formulations using a syringe, and the polymerization reaction was carried out in a regulated electronic oven according to the following cycle: 3 hours at about 45-50 C., regular temperature increase during 11 hours at about 3 C./hour, 3 hours at about 80-90 C. and 2 hours at about 60-70 C.

[0116] The molds were then disassembled to obtain lenses comprising a body of a thermoset material. The lenses were cleaned with isopropyl alcohol, then annealed for 1 h at 100 C.

[0117] For composition B, the benzotriazole UV absorber component was mixed with the ISO monomer (isocyanate part, 50.6 g) at room temperature (25 C.) until a homogeneous mixture was obtained. The dimethyl tin dichloride catalyst (40 mg) was added in the reaction mixture, which was then cooled down to 10 C. prior to addition of the thiol monomers THIOL1 (23.9 g) and THIOL2 (25.3 g), and stirred under vacuum until homogeneous. The bluing agent (200 mg) was added at the end of the preparation.

[0118] The assembled molds were filled with the final formulations using a syringe, and the polymerization reaction was carried out in a regulated electronic oven at maximum 130 C. for 1 day. The molds were then disassembled to obtain lenses comprising a body of a thermoset material. The lenses were cleaned by immersion and sonication in a surfactant solution, then rinsed and dried.

4. Formulations Prepared and Characterizations

[0119] The concentrations of the benzotriazole compounds used in the formulations prepared and the characterizations of the final lenses are shown hereunder in table 1 for composition A and table 2 for composition B.

[0120] The light cut-off wavelengths were determined from the light transmission spectra, which were recorded from a wearer's view angle using a Cary 4000 spectrophotometer from Hunter, with the back (concave) side of the lens (2 mm thickness at the center) facing the detector and light incoming on the front side of the lens, under D65 illumination conditions (daylight).

[0121] Comparison of inventive compounds of formulae IV, V and VI with comparative compounds shows that the presence of a resonant group in position 5 of the 2-hydroxyphenyl ring provides with a red shifting effect (FIG. 2). Indeed, methyl and tert-octyl substituents are not resonant groups, whereas metoxy, butoxy and amino substituents are resonant groups.

[0122] The yellowness index Yi of the prepared lenses was calculated as described above, by measuring on a white background with the above spectrophotometer the CIE tristimulus values X, Y, Z such as described in the standard ASTM E 313-05, through reflection measures, with the front (convex) side of the lens facing the detector and light incoming on said front side. This way of measuring Yi, from an observer's view angle, is the closest to the actual wearing situation.

TABLE-US-00001 TABLE 1 Benzotriazole Concentration (%) (*) Light cut-off (nm) Yi VII (Seesorb 0.05 369 1.7 703, comparative) 0.1 381 2.5 0.2 390 3.9 0.3 394 4.9 0.4 397 5.8 0.7 401 9.1 1.0 404 12.5 IV 0.025 367 2.1 0.05 379 3.3 0.1 393 5.3 0.2 402 8.9 0.3 406 12.0 0.4 409 13.8 0.7 414 20.3 Tinuvin 0.025 364 3.0 Carboprotect 0.05 373 4.7 (comparative) 0.1 392 7.9 0.2 404 12.1 0.7 417 22.2 (*) In parts by weight (X), for 100 parts by weight of the main monomer (CR-39).

[0123] As can be seen, the benzotriazole of formula IV according to the invention offers protection from UV light and interesting blue light cut levels in composition A. It is much more efficient, at iso-weight, than the best red shifted chlorobenzotriazole available on the market, Seesorb 703, in terms of UV/blue light cutting. Even massive amounts of Seesorb 703 (1 part by weight) cannot deliver a significant blue cut level (404 nm). The polymer matrix containing such a high amount of absorber is also highly plasticized. Thus, Seesorb 703 has the drawback of causing a strong plasticization effect at modest UV cut-off wavelength.

[0124] In terms of optical properties, the benzotriazole of formula IV according to the invention behaves almost similarly as the most red-shifted benzotriazole on the market, Tinuvin Carboprotect (same mass efficiency, i.e., in the final lens). Although the latter was more promising than the benzotriazole of formula IV in terms of light cut-off, when considering the absorption spectra of the respective compounds in solution (see FIG. 1, 0.4 mmol/L in ethanol, measurement in quartz tank, 2 mm optical path), Tinuvin Carboprotect underwent a dramatic decrease in light cut-off wavelength between the solution state and the solid state (final polymerized lens). For example, at a concentration of 0.1 parts by weight of UV absorber for 100 parts by weight of the main monomer (CR-39), the light cut-off wavelength was reduced from 410 nm (liquid solution) to 392 nm (solid state) for Tinuvin Carboprotect, from 400 nm (liquid solution) to 393 nm (solid state) for the inventive compound of formula IV, and from 391 nm (liquid solution) to 381 nm (solid state) for Seesorb 703.

[0125] Further, Tinuvin Carboprotect underwent degradation during the lens polymerization, leading to an increase of the level of yellowness of the lens. Globally, Tinuvin Carboprotect showed the highest Yi values for any given wavelength. At fixed light cut-off wavelength, the inventive benzotriazole of formula IV has a Yi close to that of Seesorb 703, and lower than that of Tinuvin Carboprotect (Yi9 vs. Yi12 for a light cut-off wavelength of 402 nm).

TABLE-US-00002 TABLE 2 Benzotriazole Concentration (%) (*) Light cut-off (nm) Yi VII (Seesorb 0.5 410 7.3 703, comparative) 0.75 412 9.3 1.0 414 10 1.5 416 17.8 2.0 417.5 16.5 IV 0.1 401 6.2 0.2 408 9.5 0.3 412 12.2 0.4 414 14.3 0.5 416 16 (*) In parts by weight relative to the weight of composition B.

[0126] Similar results were obtained in composition B with benzotriazole of formula IV according to the invention. It is much more efficient, at iso-weight, than compound VII (Seesorb 703), in terms of UV/blue light cutting. Even if yellowness index is slightly increased, the use of a lower amount of additive provides lenses with better mechanical properties.

[0127] FIGS. 1 and 2 also show that the inventive benzotriazole of formula VI is able to absorb at much higher wavelengths than Tinuvin Carboprotect and comparative compounds of formulae VII and VIII.

[0128] It has also been checked that the mechanical properties of a lens substrate comprising the inventive benzotriazole of formula IV were much higher than those of a lens substrate comprising the same weight of Seesorb 703.