NEAR INFRARED LIGHT-CUTTING OPTICAL ARTICLES WITH LOW RESIDUAL COLOR

Abstract

The present invention relates to an optical article having a substrate made of an optical material comprising a polymer matrix and at least one near infrared absorber, wherein T.sub.VIS is higher than or equal to 70%, T.sub.NIR is lower than or equal to 85%, T.sub.NIR and T.sub.VIS being respectively the average optical transmittance in the 780-1400 nm and in the 380-780 nm wavelength range for the optical material through a 2 mm thick layer of said optical material. This optical article can be used to protect from noxious infrared light.

Claims

1.-13. (canceled)

14. An optical article having a substrate made of an optical material comprising a polymer matrix and at least one near infrared absorber, wherein the optical material has the following properties: T.sub.VIS is higher than or equal to 70%; and T.sub.NIR is lower than or equal to 85%, in which: T.sub.VIS is the average optical transmittance in the 380-780 nm wavelength range for the optical material containing said at least one near infrared absorber through a 2 mm thick layer of said optical material; and T.sub.NIR is the average optical transmittance in the 780-1400 nm wavelength range for the optical material containing said at least one near infrared absorber through a 2 mm thick layer of said optical material.

15. The optical article of claim 14, wherein T.sub.VIS is higher than or equal to 0.95T.sub.NIR.

16. The optical article of claim 15, wherein T.sub.VIS is higher than or equal to T.sub.NIR.

17. The optical article of claim 14, 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.

18. The optical article of claim 17, wherein the polymer matrix comprises at least one polythiourethane.

19. The optical article of claim 14, wherein said at least one near infrared absorber is a polymethine, phthalocyanine, porphyrine, triphenylmethane, iminium, squarylium, croconium, dithiolene, quinone, polyperylene, pyrilium, thiopyrilium or cyanine near infrared absorber.

20. The optical article of claim 14, wherein said at least one near infrared absorber is present in the optical material in an amount lower than 100 ppm, relative to the weight of said optical material.

21. The optical article of claim 20, wherein said at least one near infrared absorber is present in the optical material in an amount ranging from 5 to 25 ppm, relative to the weight of said optical material.

22. The optical article of claim 20, wherein said at least one near infrared absorber is present in the optical material in an amount ranging from 5 to 20 ppm, relative to the weight of said optical material.

23. The optical article of claim 14, wherein the optical material further comprises at least one UV absorber.

24. The optical article of claim 14, wherein the average optical transmittance through a 2 mm thick layer of said optical material for light having a wavelength ranging from 380 nm to 780 nm T.sub.VIS is higher than or equal to 75%.

25. The optical article of claim 14, wherein the average optical transmittance for light having a wavelength ranging from 780 nm to 1400 nm T.sub.NIR is lower than or equal to 80%.

26. The optical article of claim 14, further defined as an ophthalmic lens.

27. The optical article of claim 14, wherein said substrate has a chroma C* as defined in the international colorimetric system CIE L*a*b* with the illuminant D65 lower than or equal to 4.5, for a 2 mm thick layer of said optical material.

28. The optical article of claim 27, wherein said substrate has a chroma C* as defined in the international colorimetric system CIE L*a*b* with the illuminant D65 lower than or equal to 4, for a 2 mm thick layer of said optical material.

29. The optical article of claim 14, wherein the polymer matrix consists of a polythiourethane polymer.

30. The optical article of claim 14, wherein: T.sub.VIS is higher than or equal to 75%; T.sub.NIR is lower than or equal to 80%; and T.sub.VIS is higher than or equal to T.sub.NIR.

31. A method for preparing the optical article of claim 14, comprising: obtaining a polymerizable composition comprising at least one polymerizable compound and at least one near infrared absorber; and curing said polymerizable composition so as to form an optical article substrate made of an optical material comprising a polymer matrix and said at least one near infrared absorber, wherein T.sub.VIS is higher than or equal to 70%, T.sub.NIR is lower than or equal to 85%, T.sub.NIR and T.sub.VIS being such as defined in claim 14.

32. The method of claim 31, wherein said at least one polymerizable compound is selected from allyl glycol carbonates, polythiols, episulfides, polyisocyanates, polyisothiocyanates and (meth)acrylates.

Description

EXAMPLES

[0103] 1. Chemicals Used

[0104] Optical materials were prepared from a composition comprising polymerizable monomers, at least one near infrared absorber, dimethyltin dichloride as a catalyst (CAS No. 753-73-1), Eversorb 109 as a UV absorber offering protection against blue light (CAS No. 83044-89-7), Diaresin blue J as a bluing agent (CAS No. 86090-40-6) and Zelec UN as a mold release agent.

[0105] The monomers used in the present examples were norbonane diisocyanate (ISO, CAS No. 74091-64-8), the pentaerythritol tetrakis (3-mercaptopropionate) (THIOL1, CAS No. 7575-23-7), and 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol (THIOL2, CAS No. 131538-00-6), in order to produce the MR8 polythiourethane matrix.

[0106] The near infrared absorbers according to the invention used in the examples were NIR-920A (Cyanine dye from QCR Solutions Corp) and NIR-1031A (from QCR Solutions Corp). Lumogen IR 765 (Quaterrylene dye from BASF) was used as a comparative near infrared absorber. In the MR8 resin, NIR-920A, NIR-1031A and Lumogen IR 765 respectively have a maximum absorption wavelength in the near infrared area at 951 nm, 1065 nm and 790 nm.

[0107] 2. Manufacture of Near Infrared Cutting Lenses by Casting

[0108] Convex and concave molds were assembled by using typing process. A center thickness adjustment was made to obtain 2 mm thick samples.

[0109] The formulations of examples 1-6 and comparative examples C1-C3 were prepared in small batch size by using a 100 mL thick wall bottle fitted with a magnetic stirrer, a glass tube for nitrogen intake and a vacuum connection. The near infrared and UV absorbers were mixed with the ISO monomer (isocyanate part) at room temperature (25 C.) until a homogeneous mixture was obtained or, if at least one of the absorbers was not dissolved at room temperature (25 C.), under moderate heat (30 C.). The lens of comparative example 3 comprised a blank polymer matrix, i.e., that did not contain any near infrared absorber.

[0110] The dimethyl tin dichloride catalyst was added in the reaction mixture, which was then cooled down to 10 C. prior to addition of the thiol monomers THIOL1 and THIOL2, and stirred under vacuum until homogeneous. The bluing agent and mold release agent were added at the end of the preparation.

[0111] The assembled molds were filled with the final formulations using a cleaned 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.

[0112] 3. Formulations Prepared and Characterizations

[0113] The formulations prepared and the spectral characterizations of the resulting lenses are shown in table 1 hereunder and on FIG. 1, plotting the chroma as a function of the average transmission in the near infrared region.

[0114] Transmissions in the visible and near infrared spectrum were measured in transmission mode 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).

[0115] T.sub.NIR (%) is the average transmission in the near infrared area (780-1400 nm). T.sub.VIS is the average transmission in the visible area (380-780 nm). These are non weighted arithmetic averages.

TABLE-US-00001 TABLE 1 Compound (parts by weight Examples unless otherwise specified) 1 2 3 4 5 6 C1 C2 C3 NIR-920A (NIR absorber, 5 10 20 ppm) NIR-1031A (NIR absorber, 5 10 20 ppm) IR 765 (NIR absorber, ppm) 25 100 UV absorber 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 ISO monomer 50.60 50.60 50.60 50.60 50.60 50.60 50.60 50.60 50.60 THIOL1 monomer 23.90 23.90 23.90 23.90 23.90 23.90 23.90 23.90 23.90 THIOL2 monomer 25.29 25.29 25.29 25.29 25.29 25.29 25.29 25.29 25.29 Catalyst 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 Bluing agent 0.21 0.21 0.21 0.21 0.21 0.21 0.21 0.21 0.21 Mold release agent 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 T.sub.VIS (%) 80.01 78.25 75.92 80.27 77.83 74.69 76.06 57.64 82.52 T.sub.NIR (%) 80.79 75.78 69.73 81.35 78.18 69.97 83.62 74.18 87.39 C* 2.89 3.09 3.17 3.22 3.42 4.39 3.31 8.56 2.83

[0116] As can be seen, all the lenses prepared offered protection from near infrared light. The three near infrared absorbers investigated decreased the average transmission in the near infrared area from 87.39% (comparative example 3) to 70-80% (examples 1-6). Table 1 and FIG. 1 show that the near infrared absorbers having the lowest absorption in the visible range provide lenses with the lowest residual color intensity (C*) at iso-T.sub.NIR (%). C*is the chroma of the optical material containing said at least one near infrared absorber for a 2 mm thick layer of said optical material.

[0117] The near infrared absorbers according to the invention have a very limited impact on the substrate's color. The present invention provides optical article materials that show almost no residual color intensity increase while near infrared transmission decreases: the slope value is almost zero for NIR-920A and NIR-1031A on FIG. 1.

[0118] Conversely, near infrared dyes having significant absorption in the visible range such as Lumogen IR 765 show a strong increase of C* over near infrared transmission decrease (comparative examples C1, C2), making them unsuitable to provide low color intensity lenses at relevant near infrared absorbing concentrations. In other words, the comparative near infrared absorber Lumogen IR 765 excessively increases C* of the optical material when used at amounts necessary to obtain a satisfactory decrease of the transmission in the near infrared area.