阅读说明：本技术 具有无色外观的透明光学物品 (Transparent optical article having a colorless appearance ) 是由 G·巴耶 于 2014-12-22 设计创作，主要内容包括：本发明涉及一种透明光学物品,该透明光学物品包含至少一种染料以及至少一种选择性光学增亮剂,该至少一种染料至少部分地抑制具有范围从400至460nm的波长的光,该至少一种选择性光学增亮剂通过荧光发射在范围从400至460nm的波长处的光。该光学增亮剂充当用于至少部分地平衡由该染料赋予该透明光学物品的颜色的手段,因此允许用户或观察者将所述光学物品感知为更少黄色并且甚至无色。(The present invention relates to a transparent optical article comprising at least one dye at least partially inhibiting light having a wavelength ranging from 400 to 460nm and at least one selective optical brightener that emits light by fluorescence at a wavelength ranging from 400 to 460 nm. The optical brightener acts as a means for at least partially balancing the color imparted to the transparent optical article by the dye, thus allowing a user or observer to perceive said optical article as less yellow and even colorless.)

1. A transparent optical article, comprising:

-at least one dye a at least partially inhibiting light having a wavelength ranging from 400 to 460nm, preferably from 420 to 450nm, and

-at least one optical brightener B for at least partially balancing the color imparted to the transparent optical article by the dye a, wherein said at least one optical brightener B emits light by fluorescence at a wavelength ranging from 400 to 460nm, preferably from 420 to 450nm, and wherein said dye a and said optical brightener B are different from each other.

2. The transparent optical article of claim 1, further defined as comprising a substrate and at least one layer coated on the substrate, wherein said at least one dye a and said at least one optical brightener B are incorporated into the substrate and/or said at least one layer coated on the substrate, together or separately.

3. The transparent optical article according to any one of the preceding claims, further defined as having a relative transmission coefficient in the visible spectrum Tv higher than 80%, more preferably higher than 85%.

4. The transparent optical article according to any one of the preceding claims, wherein the dye a is selected within the perylene, coumarin, porphyrin, acridine, indolenine and indol-2-subunit families.

5. The transparent optical article according to any one of the preceding claims, wherein the optical brightener B is selected from stilbenes, quinolones, coumarins, 1, 3-diphenyl-2-pyrazolines, naphthalimides, and benzoxazoles.

6. The transparent optical article according to any one of the preceding claims, wherein the optical brightener B is selected from the group consisting of bis-benzoxazoles, phenylcoumarins, methylcoumarins, and bis- (styryl) biphenyls.

7. The transparent optical article according to any one of the preceding claims, wherein the at least one dye a inhibits from 1% to 50% of light having a wavelength ranging from 420 to 450 nm.

8. The transparent optical article according to any one of claims 2 to 7, wherein the dye A is incorporated into the substrate in an amount lower than 50ppm, preferably lower than 5ppm, with respect to the weight of the substrate.

9. The transparent optical article according to any one of claims 2 to 7, wherein the dye A is incorporated into the at least one layer coated on the substrate in an amount lower than 5000ppm, preferably lower than 500ppm, with respect to the weight of said layer.

10. The transparent optical article according to any one of claims 2 to 9, wherein the optical brightener B is incorporated into the substrate in an amount lower than 200ppm, preferably lower than 50ppm, relative to the weight of the substrate.

11. The transparent optical article according to any one of claims 2 to 9, wherein the optical brightener B is incorporated into the said layer in an amount lower than 200ppm, preferably lower than 50ppm, relative to the weight of at least one layer coated on the substrate.

12. The transparent optical article according to any one of the preceding claims, further defined as having a yellowness index Yi lower than 10, preferably lower than 5.

13. The transparent optical article according to any one of the preceding claims, further defined as having a whiteness index Wi higher than 40.

14. The transparent optical article according to any one of the preceding claims, further defined as passive.

15. The transparent optical article according to any one of the preceding claims, further defined as an optical lens, preferably an ophthalmic lens.

Technical Field

The present invention relates to the field of optical devices, and more particularly to a transparent optical article, preferably an ophthalmic lens, which maintains a predominantly colorless appearance while comprising a filter intended to protect from blue light.

Background

Visible light as perceived by humans extends approximately over a spectrum of wavelengths ranging from 380nm wavelengths to 780 nm. The portion of this spectrum ranging from about 380nm to about 500nm corresponds to high-energy blue light (substantially).

Many studies (see, e.g., schel E. (kitchen E.), (The effects of blue light on eye health), Journal of Visual Impairment and Blindness (Journal of Visual Impairment and Blindness), volume 94, 6 th, 2000 or Glazer-Hockstein et al, Retina (Retina), volume 26, 1 st, pages 1-4, 2006) indicate that blue light has a phototoxic effect on human eye health, and in particular on The Retina.

Indeed, ocular photobiology studies (alvira p.v., et al, "effect of Age-Related Maculopathy and The Impact of The Blue Light Hazard," scandinavia ophthalmology, Acta ophthalmology, scan, et al, pages 4-15, 2006) and clinical trials (tomm s.c, "sun Light and Age-Related Maculopathy 10-Year Incidence" (sunshine and The 10-Year inclusion of Age-Related Maculopathy), "Beaver day Eye Study (The Beaver day Eye Study), journal of ophthalmology (Arch Ophthalmol 2004), volume 122, page 750, Year 2004) argue that exposure to Age-Related Maculopathy, such as severe Age-Related macular degeneration, may be severe under intense exposure.

It is therefore proposed to limit the exposure to potentially harmful blue light, in particular with respect to wavelength bands with an increased risk (see in particular table B1, standard ISO 8980-3: 2003(E), reference B (λ) blue light risk function).

For this purpose, it may be desirable for the spectacle wearer to wear an ophthalmic lens in front of each of the two eyes that prevents or limits the transmission of phototoxic blue light to the retina. Such lenses may also provide increased visual performance due to increased contrast sensitivity.

It has been proposed, for example in patent application WO 2008/024414, to at least partially cut off the troublesome portion of the blue light spectrum from 400nm to 460nm by absorption or by reflection by means of a lens comprising a film which partially suppresses light in the appropriate wavelength range. This can also be done by incorporating a yellow dye into the optical element.

However, blocking blue light affects the color balance, color perception (if one looks through the optical device), and color (where the optical device is perceived). Indeed, blue-blocking optics incorporating dyes that at least partially suppress light having wavelengths ranging from 400 to 460nm appear yellow, brown, or amber. This is aesthetically unacceptable for many ophthalmic applications and may interfere with the normal color perception of the user if the device is an ophthalmic lens.

Efforts have been made to compensate for the yellowing effect of conventional blue-blocking filters. For example, blue-blocking lenses have been treated with additional dyes, such as blue, red, or green dyes, to counteract this yellowing effect. However, this technique undesirably reduces the overall optical wavelength transmission except for the blue wavelengths, which results in optical attenuation for the lens user.

In view of the above, there is a need for an optical article capable of at least partially blocking blue light, which optical article may further provide an acceptable color modification, i.e. the optical article is perceived by someone observing the optical article as being mainly colorless. There is also a need for an acceptable overall light transmission level, and an acceptable color perception by the user, i.e. the optical article should not significantly impair the wearer's color perception in the case of an ophthalmic system. In particular, there is a need for an optical article that allows selective blocking of blue wavelengths while transmitting at least 80% of visible light.

Object of the Invention

The inventors of the present invention found that optical brighteners (also known as Fluorescent Whitening Agents (FWAs), Optical Brighteners (OBAs) or Fluorescent Brighteners (FBAs)) can be used as a means of color balancing, i.e., to minimize and preferably eliminate the change in color perception caused by blue blocking dyes incorporated into optical systems, as blue light emitted by optical brighteners can compensate for the attenuated blue color of materials treated with the dyes and restore the original colorless appearance.

To address the needs of the present invention and to remedy the noted shortcomings of the prior art, the applicant provides a transparent optical article comprising:

-at least one dye a at least partially inhibiting light having a wavelength ranging from 400 to 460nm, preferably from 420 to 450nm, and

-at least one optical brightener B for at least partially balancing the color imparted to the transparent optical article by the dye a, wherein said at least one optical brightener B emits light by fluorescence at a wavelength ranging from 400 to 460nm, preferably from 420 to 450nm, and wherein said dye a and said optical brightener B are different from each other.

The combined use of an optical brightener B and a dye a (also referred to in this specification as blue blocking dye or yellow dye) in the substrate of the transparent optical article and/or in at least one layer coated on the substrate, while allowing protection of the user from blue light and masking the yellow colour imparted by the dye.

Detailed Description

As used herein, when an article includes one or more layers or coatings on its surface, "depositing a layer or coating on the article" means depositing a layer or coating on the uncovered (exposed) surface of the exterior coating (i.e., the coating furthest from the substrate) of the article.

As used herein, a coating "on" or already deposited on a substrate/coating is defined as a coating that: the coating (i) is disposed over the substrate/coating, (ii) does not have to be in contact with the substrate/coating, that is, one or more intermediate coatings may be interposed between the substrate/coating and the associated coating (however, it preferably contacts said substrate/coating), and (iii) does not have to completely cover the substrate/coating. When "coating 1 is said to be located below coating 2," it is understood that coating 2 is farther from the substrate than coating 1.

In this specification, an optical article is understood to be transparent when the image viewed through said optical article is perceived without significant loss of contrast, i.e. when the image formed by said optical article is obtained without adversely affecting the quality of the image. This definition of the term "transparent" may apply to all objects so defined in this specification.

In the present invention, the transparent optical article preferably emits light whose energy source is only the light-visible, ultraviolet or infrared-entering the transparent optical article. In other words, the light emitted by the optical system is transmitted incident light or reflected incident light or light re-emitted by means of fluorescence or phosphorescence after absorption of the incident light. Indeed, the transparent optical article according to the invention preferably does not comprise any electrical to optical sensors like lamps-fluorescent or incandescent-or light emitting diodes. In this embodiment, the transparent optical article is defined as passive.

The transparent optical article according to the invention is preferably an optical lens or a lens precursor, more preferably an ophthalmic lens or a lens precursor.

The term "ophthalmic lens" is used to refer to a lens that fits into a spectacle frame to protect the eye and/or correct vision. The lens may be selected from the group consisting of afocal, monofocal, bifocal, trifocal and progressive lenses. Although ophthalmic optics is the preferred field of the invention, it will be understood that the invention can be applied to other types of transparent optical elements, such as, for example, lenses for optical instruments, filters particularly for photography or astronomy, optical sighting lenses, eye goggles, optics of lighting systems, etc.

The transparent optical article preferably comprises a substrate and at least one layer coated on the substrate. If the transparent optical article is an optical lens, the transparent optical article may be coated on its convex main side (front side), concave main side (back side), or both. The transparent optical article may also be a flat optical article. When the optical article has a front major surface and a rear major surface, its rear surface is preferably not coated with any layer comprising an optical brightener.

In the sense of the present invention, a substrate is understood to mean an uncoated substrate and generally has two main faces. The substrate may in particular be an optically transparent material having the shape of an optical article, such as an ophthalmic lens destined to be mounted on spectacles. In this context, the term "substrate" is understood to mean the transparent base constituent material of the optical lens and more particularly of the ophthalmic lens. This material acts as a support for the stack of one or more coatings.

The substrate of the article of the invention may be an inorganic or organic glass, for example made of a thermoplastic or thermosetting plastic, generally chosen from ophthalmic grade transparent materials used in the ophthalmic industry.

As particularly preferred classes of substrate materials, mention may be made of polycarbonates, polyamides, polyimides, polysulfones, copolymers of polyethylene terephthalate and polycarbonate, polyolefins, such as polynorbornene, resins resulting from the polymerization or (co) polymerization of alkylene glycol bisallyl carbonate, such as polymers and copolymers of diethylene glycol bis (allyl carbonate) (for example under the trade nameThe corresponding lenses sold by PPG Industries company (PPG Industries company) are referred to as those from the road of Sight (ESSILOR)Lenses), polycarbonates, such as those derived from bisphenol-a, (meth) acrylic or thio (meth) acrylic polymers and copolymers, such as Polymethylmethacrylate (PMMA), urethane and thiourethane polymers and copolymers, epoxy polymers and copolymers, episulfide polymers and copolymers.

In some applications, it is preferred that the major surface of the substrate is further coated with one or more functional coatings to improve optical and/or mechanical properties. The term "coating" is understood to mean any layer, stack of layers or film that can be in contact with the substrate and/or with another coating (for example a sol-gel coating or a coating made of an organic resin). The coating may be deposited or formed by various methods including wet processing, gas treatment, film transfer. These functional coatings typically used in optical devices may be, but are not limited to, impact and/or adhesion primers, abrasion and/or scratch resistant coatings, antireflective coatings, polarizing coatings, photochromic coatings, or antistatic coatings, or stacks made of two or more such coatings, in particular impact resistant primer coatings coated with abrasion and/or scratch resistant coatings.

The abrasion-and/or scratch-resistant coating (hard coating) is preferably a hard coating based on poly (meth) acrylates or silanes. The hard abrasion and/or scratch resistant coatings recommended in the present invention include coatings obtained from compositions based on silane hydrolysates (sol-gel process), in particular based on epoxysilane hydrolysate-based compositions, such as those described in US patent applications US 2003/0165698 and US 4,211,823.

The primer coating that improves the impact resistance and/or adhesion of the additional layer in the final product is preferably a polyurethane latex or an acrylic latex. The primer coating and the abrasion and/or scratch resistant coating may be chosen from those described in application WO 2007/088312.

The antireflective coating that improves the antireflective properties of the final optical article by reducing the reflection of light at the article-air interface over a relatively large range of the visible spectrum can be any antireflective coating typically used in the field of optics, in particular ophthalmic optics. As is well known, antireflective coatings conventionally comprise a single layer or a stack of layers consisting of dielectric or sol-gel materials. These are preferably multilayer coatings comprising a layer with a high refractive index (HI, n >1.5) and a layer with a low refractive index (LI, n.ltoreq.1.5).

The structure and preparation of antireflective coatings are described in more detail in patent applications WO 2010/109154 and WO 2012/153072.

Coatings according to the present invention such as primers, hardcoats, and antireflective coatings can be deposited using methods known in the art, including spin coating, dip coating, spray coating, evaporation, sputtering, chemical vapor deposition, and lamination.

According to the invention, the dye a and the optical brightener B are incorporated, together or separately, into the transparent optical article, preferably into the substrate and/or at least one layer coated on the substrate, while still obtaining the advantages and benefits of the invention in terms of health and decorative appearance.

In the system according to the invention, the dye a and the optical brightener B can both be incorporated in the substrate, both in the same coating (for example a primer coating, a hard coating or an antireflection coating), one in the substrate and the other in a coating deposited on any one face of the transparent optical article, which may be convex, concave or flat, separately within (at least) two different coatings, or a combination of these embodiments can be implemented. For example, the blue blocking dye may be in a hard coating and the optical brightener included in a primer coating, or the blue blocking dye may be included in the substrate and the optical brightener included in a coating. In case the dye and the optical brightener are comprised in (at least) two different coatings, it is not necessary to deposit the coatings on the same side of the transparent optical article. They may be deposited on either side of the transparent optical article, or on both sides of the transparent optical article.

Several dyes and/or several optical brighteners may be incorporated in the same or different layers deposited on the substrate and/or at the surface of the substrate.

In a preferred embodiment, the transparent optical article comprises a substrate into which the blue-blocking dye a is incorporated. The dye (and/or the optical brightener) may be incorporated into the substrate by methods well known in the art, such as:

I. the dipping or imbibing method consists in dipping the substrate in an organic solvent and/or a hot aqueous colouring bath, preferably an aqueous solution, for several minutes. Substrates made of organic materials, such as organic lens substrates, are most often tinted in the bulk of the material by immersion in an aqueous tinting bath which is heated to a temperature on the order of 90 c and in which the dye has been dispersed. The dye thus diffuses below the surface of the substrate and the color density is obtained by adjusting the amount of dye diffused in the bulk of the substrate,

diffusion processes described in JP 2000-314088 and JP 2000-241601, involving a permeable temporary coating, or

Contactless colouring using sublimable materials, as described in US 6534443 and US 6554873, or

Incorporating a blue absorbing dye during the manufacture of the substrate itself, for example by casting or injection moulding.

In another embodiment, the transparent optical article comprises a substrate and at least one layer coated on the substrate, wherein the dye a is incorporated into said at least one layer coated on the substrate. For example, the dye may be incorporated into a hard coat and/or a primer coat that generally promotes adhesion of the hard coat to the substrate. The dye may also be incorporated into a film that is subsequently transferred, laminated, fused or glued to the substrate.

Several methods of optical fabrication familiar to those skilled in the art are known for incorporating the dye (and/or the optical brightener) in a layer. The blue-blocking dye may be deposited simultaneously with the layer, i.e. when the layer is prepared from a liquid coating composition, the dye may be incorporated (directly or e.g. as dye impregnated particles) or dissolved in said coating composition before the coating composition is applied (mixed in situ) at the surface of the substrate and hardened.

The dye (and/or the optical brightener) may also be included in a coating in a separate process or subprocess. For example, after the coating has been deposited at the surface of the substrate, the dye may be included in the coating using an immersion colouring process similar to that mentioned for colouring the substrate, i.e. by means of a colouring bath at elevated temperature, by the diffusion process disclosed in US 2003/0020869 in the name of the applicant, by the process disclosed in US 2008/127432 in the name of the applicant using a printed primer subjected to printing (using an inkjet printer), by the process disclosed in US 2013/244045 in the name of the applicant involving printing with sublimation dyes by means of a thermal transfer printer, or by the process disclosed in US 2009/047424 in the name of the applicant using a porous layer to transfer the colourant into the substrate. The dye may also be sprayed onto the surface prior to curing (e.g., thermal or UV curing), drying, or application of the coating.

When performing ink jet printing, it is generally necessary to modify the surface of the article to receive ink, typically by applying an ink-receptive coating on the surface of the article. The ink receptive coating may be a permanently colorable coating or a temporary colorable coating that acts as a temporary support from which the dyes are transferred into the article. The dyes may be transferred in the substrate itself or in a coating of the substrate adjacent to the ink-receptive coating. Inkjet printing for pigmented substrates or coatings is described in more detail in US 2013/0230649 in the name of the applicant.

The methods for incorporating the optical brightener B into the substrate or coating are generally the same as those disclosed for incorporating the dye. Obviously, a combination of several of the methods described above can be used to obtain a transparent optical article having incorporated therein a dye a and an optical brightener B.

The amount of optical brightener used in the present invention is an amount sufficient to provide a transparent optical article that does not have a yellow appearance, while the amount of dye used in the present invention is an amount sufficient to provide satisfactory protection from blue light.

When incorporated into the substrate, the optical brightener is preferably used in an amount lower than 200ppm, more preferably lower than 50ppm, relative to the weight of said substrate.

When incorporated into a layer coated on the substrate, the optical brightener is preferably used in an amount lower than 200ppm, more preferably lower than 50ppm, relative to the weight of said layer.

When incorporated into the substrate, the blue-blocking dye is preferably used in an amount of less than 50ppm, more preferably less than 5ppm, relative to the weight of the substrate.

When incorporated into a layer coated on the substrate, the blue-blocking dye is preferably used in an amount lower than 5000ppm, more preferably lower than 500ppm, relative to the weight of said layer.

Naturally, the respective amounts of optical brightener and blue blocking dye must be adapted to each other to produce a transparent, colorless element. In particular, one skilled in the art will recognize that the amount of optical brightener desired will vary depending on several factors, including the nature and amount of the dye used. For this purpose, the optimum amount of each compound can be determined by simple laboratory tests.

Clearly, if both the substrate and the coating of the transparent optical article according to the invention are not coloured, it may simply appear colourless.

As used herein, a dye may refer to both a pigment and a colorant, i.e., may or may not be soluble in its vehicle. The dyes may be used alone or in combination.

The chemical nature of the dye A is not particularly limited provided that it has an absorption peak, ideally a maximum absorption peak in the range of 400-450 nm, preferably 420-450 nm. Preferably, dye a, acting as a means for at least partially inhibiting light having a wavelength ranging from 400 to 460nm, selectively inhibits light in the range of 400nm-460nm, and more preferably in the range of 420nm-450 nm. As used herein, if a means "selectively inhibits" at least some transmission within a wavelength range, that means inhibits that range while having little or no effect on visible wavelength transmission outside that wavelength range.

The one or more dyes incorporated in the transparent optical article preferably absorb radiation such that they suppress from 1% to 50%, more preferably from 10% to 40%, ideally from 10% to 30% of light having a wavelength ranging from 400 to 460 nm. They preferably suppress from 1% to 50%, more preferably from 10% to 40%, ideally from 10% to 30% of light having a wavelength ranging from 420 to 450 nm. These absorptions can be controlled by dye concentration and measured relative to the amount of light that would be transmitted at the same wavelength in the absence of these dyes.

The blue-blocking dye may be selected from, but is not limited to, these families: perylene, coumarin, porphyrin, acridine, indolenine (indolin), which is a synonym for 3H-indole, and the indol-2-subunit family.

Preferred blue-blocking dyes have narrow absorption bands in the 400-460nm range of the electromagnetic spectrum, preferably 420-450 nm. Ideally, the absorption band is centered around 430 nm.

The most preferred dye according to the present invention is perylene, which exhibits desirable spectral characteristics and interesting injection processability characteristics. Indeed, perylene is a selective yellow dye that absorbs no, or very little, in the visible region of the spectrum outside the wavelength range of 400-460 nm.

As is well known, optical brighteners are substances that absorb light in the UV and violet region (typically at 340-370 nm) and re-emit light primarily in the blue region of the visible spectrum by fluorescence. They may be used alone or in combination.

The chemical nature of the optical brightener is not particularly limited, provided that it is capable of emitting light by fluorescence (ideally maximum fluorescence) at a wavelength ranging from 400 to 460nm, preferably from 420 to 450 nm.

Preferably, the optical brightener absorbs less than 30%, more preferably less than 20%, even more preferably less than 10%, ideally less than 5% of light having a wavelength ranging from 400 to 460 nm. It preferably absorbs less than 30%, more preferably less than 20%, even more preferably less than 10%, ideally less than 5% of light having a wavelength ranging from 420 to 450 nm. The optical brightener preferably has no absorption peak maximum, even better no absorption peak in the range of 400-460nm, preferably in the range of 420-450 nm.

The optical brightener may be selected from, but is not limited to, these families: stilbene, quinolone, coumarin, 1, 3-diphenyl-2-pyrazoline, naphthalimide, combined heteroaromatic compounds such as pyrenyl-triazines or other combinations of the following heterocyclic compounds, for example thiazole, pyrazole, oxadiazole, fused polyaromatic systems or triazines (either directly connected to one another or via a conjugated ring system), benzoxazoles (in particular benzoxazoles which are substituted at the 2-position by a conjugated ring system which preferably comprises ethylene, styrene, stilbene, benzoxazole and/or thiophene groups). Preferred families of optical brighteners are bis-benzoxazoles, phenylcoumarins, methylcoumarins, and bis- (styryl) biphenyls, which are described in more detail in a.g. oertli, Plastics Additives Handbook, 6 th edition, editors h.zweifel, d.maier, m.schiller, 2009.

A specific example of a commercially available bis-benzoxazole optical brightener is available from Eastman ChemicalCompounds, e.g.OB、OB-1 andOB-3 from ClariantCompounds such as Hostalux ACK, Hostalux CP01, Hostalux EBU, Hostalux EF, Hostalux ERE, Hostalux EREN, Hostalux ES2R, Hostalux ESR, Hostalux ETB 300, Hostalux ETBN, Hostalux KCB, Hostalux KS1B, Hostalux KSB3, Hostalux KSC, Hostalux KSN, Hostalux NR, Hostalux NSM, Hostalux PFC, Hostalux PFCB, Hostalux PN, Hostalux PNB, and Hostalux PR, from Sumitomo Chemical CoCompounds (styryl (styril) -bis-benzoxazoles), e.g.B、PEN、PHR、HCS、PCS。

A specific example of a commercially available methyl-coumarin optical brightener is that from Eastern Color and chemical company (Eastern Color)&Chemical Co.))Compounds such as Eccowhite 1132MOD, Eccowhite 2013, Eccowhite 2790, Eccowhite 5261, Eccowhite AEA-HF, Eccowhite Nylon FW, Eccowhite OP, Eccowhite PSO, Eccowhite DM-04 MOD.

Another useful class of optical brighteners is from BASFFamily, which includes both bis-benzoxazole and bis- (styryl) biphenyl compounds, such as Tinopal ABP- ｃA, Tinopal ABP-X, Tinopal ASP, Tinopal BPO, Tinopal ec, Tinopal HST, Tinopal HW, Tinopal MSP, Tinopal NP, Tinopal SPP-N, Tinopal SPP-Z, Tinopal UP HC DD, Tinopal UP, Tinopal CBS-X, and Tinopal OB.

Other useful optical brighteners that can be used in the present invention are described in Fluorescent Whitening agents (Fluorescent Whitening agents), Anders g.eqs, Environmental quality and safety (volume IV of supplement) stuttgart george press, 1975.

Preferred optical brighteners have a high fluorescence efficiency, i.e. as a major part of the visible light re-emitting the energy they have absorbed.

The most preferred optical brighteners are:

i) by Istman Chemical company (Eastman Chemical)2, 2' - (1, 2-ethylidenebis-4, 1-phenylene) bisbenzoxazole sold under OB-1 having the structure:

ii) 2, 5-thienylbis (5-tert-butyl-1, 3-benzoxazole) having the following structure, sold under the trade name Tinopal OB by Pasteur:

according to the present invention, a specific yellow dye is associated with an optical brightener having a fluorescent emission that will best match the absorption spectrum of the dye, and vice versa. The properties of the dye and optical brightener allow for the adjustment of the absorption/emission peak position.

In a preferred embodiment, the transparent optical article according to the invention comprises a dye a and an optical brightener B such that the difference (expressed in absolute value) between the maximum absorption value amax (a) of dye a and the maximum fluorescence emission value amax (B) of the optical brightener B is lower than 15nm, more preferably lower than 10nm and ideally lower than 5 nm. In the context of the present application, λ max (a) and λ max (B) are measured in dichloromethane.

Perylene as blue blocking dye and 2, 2' - (1, 2-ethylenediylbis-4, 1-phenylene) bisbenzoxazole(s) as optical brightenersCombinations of OB-1) are particularly preferred, since the latter fluorescesThe properties perfectly match the absorption spectrum of perylene.The maximum fluorescence emission wavelength of OB-1 is 436nm, while perylene has an absorption maximum at 434 nm.

The transparent optical article according to the invention has improved color properties, which can be quantified by a whiteness index Wi and a yellowness index Yi.

The whitening effect of the optical brightener B, in other words the whiteness of the transparent optical articles of the invention, can be evaluated by means of colorimetric measurements based on the CIE tristimulus value X, Y, Z (as described in the standards ASTM E313-73(1993) and ASTM D1925-70 (1988)). The transparent optical article according to the invention preferably has a high whiteness index Wi, i.e. higher than 40, as measured according to ASTM E-313-73. Wi is calculated by Taube's equation (Wi-4B-3G, parameters B (blue) and G (green) are determined from tristimulus values X, Y, Z, where G-Y and B-0.847Z).

The transparent optical article according to the present invention preferably has a low yellowness index Yi, i.e. lower than 10, more preferably lower than 5, as measured according to ASTM D-1925. Yi can be determined from CIE tristimulus values X, Y, Z by the following relationship:

Yi＝(128X-106Z)/Y。

the transparent optical article according to the invention preferably has a relative transmission coefficient Tv in the visible spectrum higher than 80%, more preferably higher than 85%. The Tv coefficient is as defined in the standard NF EN 1836 and corresponds to the wavelength range of 380-.