Epoxy functional composition protecting dyes from photo-degradation and cured coatings prepared therefrom

Abstract

The present invention relates to an optical filtering coating composition, comprising at least one dye that at least partially inhibits transmission of light within the 400-500 nm wavelength range and has a conjugated chromophore, one or more epoxy compounds comprising at least one cycloaliphatic or aryl group, the ratio of the number of carbon atoms/the number of oxygen atoms in said epoxy compound being higher than or equal to 3, and the dry extract weight of such epoxy compounds present in the composition representing more than 33% of the dry extract weight of the composition. The coating composition can be applied on the main surface of the substrate of an optical article.

Claims

1. An optical filtering coating composition for improving photostability of at least one absorbing dye, comprising: at least one absorbing dye that is selected from a porphyrin and a quinoline, has a conjugated chromophore and at least partially inhibits transmission of light within the 400-500 nm wavelength range; one or more epoxy compounds comprising at least one cycloaliphatic or aryl group; and the ratio: number of carbon atoms/number of oxygen atoms in said at least one epoxy compound is higher than or equal to 3, and the dry extract weight of such epoxy compounds represents more than 33% of the dry extract weight of the composition; wherein said optical filtering coating composition provides a coating upon curing, in which the photo-degradation of said absorbing dye is less than 30% after exposure of the coating deposited on a reference lens for 40 hours to light in a Q-SUN Xe-3 xenon test chamber; wherein the photo-degradation is calculated by the formula:
(T%.sub.dye 40 h−T%.sub.dye 0 h)/(T%.sub.ref 40 h−T%.sub.dye 0 h) where: T%.sub.dye 40 h is the transmittance % of the reference lens coated with said coating after 40 hours light exposure; T%.sub.dye 0 h is the transmittance % of the reference lens coated with said coating before light exposure; and T%.sub.ref 40 h is the transmittance % of the uncoated reference lens after 40 hours light exposure; wherein the transmittances are measured at a wavelength corresponding to a maximum absorption peak of said absorbing dye.

2. The composition of claim 1, wherein the ratio: number of carbon atoms/number of oxygen atoms is higher than or equal to 3.3.

3. The composition of claim 2, wherein the ratio: number of carbon atoms/number of oxygen atoms is higher than or equal to 3.5.

4. The composition of claim 1, wherein the ratio: number of carbon atoms/number of oxygen atoms is higher than or equal to 4.

5. The composition of claim 4, wherein the ratio: number of carbon atoms/number of oxygen atoms is higher than or equal to 4.5.

6. The composition of claim 1, wherein the absorbing dye is present in an amount ranging from 0.01 to 1.25% relative to the dry extract weight of the composition.

7. The composition of claim 1, wherein the absorbing dye at least partially inhibits transmission of light within the 415-455 nm wavelength range.

8. The composition of claim 1, wherein the absorbing dye selectively inhibits transmission of light within said wavelength range.

9. The composition of claim 1, further defined as neither comprising any UV absorber nor free radical scavenger.

10. The composition of claim 1, further defined as comprising at least one UV absorber and/or at least one free radical scavenger.

11. The composition of claim 1, wherein the cycloaliphatic group is a cycloalkyl group.

12. The composition of claim 1, wherein the epoxy compound comprising at least one cycloaliphatic or aryl group comprises at least one aryl glycidyl ether group or β-(3,4-epoxycyclohexyl)alkyl group.

13. The composition of claim 1, wherein the epoxy compound comprising at least one cycloaliphatic or aryl group comprises at least two epoxy groups.

14. An optical article having at least one main surface comprising a coating improving photostability of at least one absorbing dye, wherein the coating is obtained by depositing on a substrate and curing an optical filtering coating composition comprising: at least one absorbing dye that is selected from a porphyrin and a quinoline, has a conjugated chromophore and at least partially inhibits transmission of light within the 400-500 nm wavelength range; one or more epoxy compounds comprising at least one cycloaliphatic or aryl group; and the ratio: number of carbon atoms/number of oxygen atoms in said at least one epoxy compound is higher than or equal to 3, and the dry extract weight of such epoxy compounds represents more than 33% of the dry extract weight of the composition, wherein the photo-degradation of said absorbing dye contained in said coating is less than 30% after exposure of the coating deposited on a reference lens for 40 hours to light in a Q-SUN Xe-3 xenon test chamber; wherein the photo-degradation is calculated by the following formula:
(T%.sub.dye 40h−T%.sub.dye 0h)/(T%.sub.ref 40h−T%.sub.dye 0h) where: T%.sub.dye 40 h is the transmittance % of the reference lens coated with said coating after 40 hours light exposure; T%.sub.dye 0 h is the transmittance % of the reference lens coated with said coating before light exposure; and T%.sub.ref 40 h is the transmittance % of the uncoated reference lens after 40 hours light exposure; wherein the transmittances are measured at a wavelength corresponding to a maximum absorption peak of said absorbing dye.

15. The optical article of claim 14, further comprising at least one mineral layer.

16. The optical article of claim 15, wherein the at least one mineral layer is at least one mineral layer of an antireflection coating.

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

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

19. A process for improving photostability of at least one absorbing dye contained in a coating, said process comprising: curing an optical filtering coating composition comprising said at least one epoxy compound and said at least one absorbing dye; wherein said at least one epoxy compound comprises at least one cycloaliphatic or aryl group, with a ratio of number of carbon atoms/number of oxygen atoms in the at least one epoxy compound being greater than or equal to 3; wherein said at least one absorbing dye is selected from a porphyrin and a quinoline, has a conjugated chromophore and at least partially inhibits transmission of light within the 400-500 nm wavelength range; and wherein the dry extract weight of said at least one epoxy compound represents more than 33% of the dry extract weight of the composition; wherein the photo-degradation of said absorbing dye contained in said coating is less than 30% after exposure of the coating deposited on a reference lens for 40 hours to light in a Q-SUN Xe-3 xenon test chamber, wherein the photo-degradation is calculated by the following formula:
(T%.sub.dye 40h−T%.sub.dye 0h)/(T%.sub.ref 40h−T%.sub.dye 0h) where: T%.sub.dye 40 h is the transmittance % of the reference lens coated with said coating after 40 hours light exposure; T%.sub.dye 0 h is the transmittance % of the reference lens coated with said coating before light exposure; and T%.sub.ref 40 h is the transmittance % of the uncoated reference lens after 40 hours light exposure; wherein the transmittances are measured at a wavelength corresponding to a maximum absorption peak of said absorbing dye.

Description

EXAMPLES

(1) The optical articles used in the examples comprise an ORMA® lens substrate from ESSILOR, having a 65 mm diameter, a refractive index of 1.50, a power of −2.00 diopters and a thickness of 1.2 mm.

(2) Various epoxy coating compositions were prepared and are shown in the tables below. Some of them were compositions of epoxy homopolymers (examples 1, 2 and comparative examples C1-C2), while the others were compositions of epoxy copolymers. The compositions comprise at least one epoxy compound that is not a silicon compound having at least one hydrolyzable group directly linked to the silicon atom, a Lewis acid polymerization catalyst for the epoxy groups (Nacure® Super A218, metal salt of triflic acid in n-butanol, 25% wt., from King Industries), a surfactant (EFKA® 3034, which is a fluorocarbon containing organically modified polysiloxane, 50% wt. in methoxypropanol sold by CIBA), propylene glycol methyl ether as a solvent (Dowanol® PM from Dow Chemical Company) and a dye. Optional compounds were included in some compositions, such as colloidal silica (MA-ST-HV® from Nissan Chemical, 30% wt. dispersion in methanol) and hydrolyzed epoxysilanes.

(3) The following epoxy compounds according to the invention were used in the examples: UVACure® 1500 (3′,4′-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, from Allnex USA Inc.) and EPALLOY® 9000 (1,1,1-tris-(p-hydroxy phenyl) ethane triglycidyl ether).

(4) The following comparative epoxy compounds were investigated: EGDGE (ethylene glycol diglycydyl ether), Erisys™ GE-30 (trimethylolpropane triglycidyl ether, abbreviated as GE-30, from CVC thermoset Specialties), Erisys™ GE-60 (sorbitol hexaglycidyl ether, abbreviated as GE-60, from CVC thermoset Specialties), Glymo (3-glycidoxypropyl-trimethoxysilane, from Evonik Industries) and KBE-402 (3-glycidoxypropyl methyldiethoxysilane). These epoxy compounds are relatively electron rich monomers, and the last two of them are epoxysilanes, which generate hybrid epoxy copolymers when used together with epoxy compounds devoid of reactive silicon atom.

(5) The structures of the various epoxy compounds devoid of silicon atom are recalled hereunder:

(6) TABLE-US-00001 Epoxy EGDGE Erisys ™ GE-30 Erisys ™ GE-60 UVACure ® EPALLOY ® compound (comparative) (comparative) (comparative) 1500 9000 Structure 0 C/O ratio 2 2.5 2 3.5 4.8

(7) The following dyes were used in the various compositions:

(8) Dye A: ABS-420® (λ max=˜421 nm), from Exciton Inc. (blue light blocking dye)

(9) Dye B: Solvent Yellow 114 (λ max=˜446 nm, quinoline dye), from American Dyestuff Corp.

(10) Dye C: Solvent Blue 45 (λ max=˜624 nm, anthracene dye, also called Savinyl Blue RS), from Clariant International Ltd.

(11) The prepared formulations contained around 39-44% by weight of solids (dry extract weight relative to the weight of the composition). The dye was the last ingredient added to the compositions. Each of the coating solutions was deposited by spin coating onto a cleaned face of an Orma® lens previously cleaned with diluted NaOH (500 rpm for 5 s, then 1000 rpm for 10 s, examples 1-2, C1-C2), or by dip coating onto both faces of such lens (at a speed of 2.0 mm/s, all examples except examples 1-2, C1-C2). A pre-curing at 80° C. for 15 minutes and a curing at 110° C. for 3 hours were then performed. The coating thicknesses were 5 μm.

(12) Evaluation of the Coating Performances

(13) a) Dye photo-degradation in epoxy coatings was measured by subjecting the prepared lenses to the Q-sun test. This test uses a Q-SUN® Xe-3 xenon chamber, purchased from Q-LAB, at a relative humidity of 20% (±5%) and at a temperature of 23° C. (±5° C.), reproducing full spectrum sunlight.

(14) A sample lens coated with an epoxy coating containing at least one dye was measured by a Cary® 50 spectrophotometer to get a transmission (T%) spectrum. Then the lens was introduced in the xenon chamber and its convex side was exposed to the light for 40 h inside the Q-sun chamber. The lens was measured by the Cary® 50 spectrophotometer again to get a T % spectrum. An uncoated Orma® lens was used as the reference lens, tested before & after the 40 h sun exposure test as well. Because there was very little change of the Orma® lens spectrum before & after the sun exposure test, its change was neglected during the calculation.

(15) The formula used to calculate the photo-degradation level of the dye in an epoxy coating coated on Orma® lens is described below, using the transmittance % at λ max:
Dye photo-degradation=(T%.sub.dyeλ max 40 h−T%.sub.dyeλ max 0 h)/(T%.sub.Orma λ max 40 h−T%.sub.dyeλ max 0 h)

(16) For example, an Orma® lens coated with a blue dye coating (λ max of the dye: 580 nm) showed 80% of transmittance initially, which changed to 86% after 40 h of Q-sun exposure test. The reference Orma® lens showed 92% of initial transmittance at 580 nm, which only changed to 91.8% after 40 h of Q-sun exposure, indicating almost no change of Orma® lens at this wavelength. In this case, blue dye photo-degradation=(86-80)/(92-80)*100=50%.

(17) b) Haze was measured as disclosed in WO 2012/173596, on a Hazeguard XL 211 Plus apparatus from BYK-Gardner in accordance with the standard ASTM D1003-00. As haze is a measurement of the percentage of transmitted light scattered more than 2.5° from the axis of the incident light, the smaller the haze value, the lower the degree of cloudiness. Generally, for optical articles described herein, a haze value of less than or equal to 0.3% is acceptable, more preferably of less than or equal to 0.2%.

(18) c) Oxygen transmission rate was measured according to ASTM F1307-02 using a MOCON OX-TRAN® Model 2/21. The coated lens or BOPP (biaxially-oriented polypropylene) film samples were glued on metal masks using epoxy glue, allowed for air drying overnight in the ambient conditions, near 23° C., 50% relative humidity. The test conditions were at 35° C., 70% relative humidity. Minimum seven cycles of measurements were performed. One side of testing samples was exposed to a dry carrier gas (nitrogen with <2% hydrogen) and the other side was exposed to 100% dry oxygen gas. A permeation rate was calculated from the flow rate and concentration of the certified tank gas.

(19) Compositions and results

(20) The various ingredients used to prepare the compositions 1-8 according to the invention and the comparative compositions C1-C2 as well as the results of the tests performed are shown in the tables hereunder.

(21) TABLE-US-00002 Example C1 C2 Epoxy EGDGE 37.7 GE-30 37.7 compound (%) Nacure ® 5.7 5.7 Super A218 (%) EFKA ® 0.1 0.1 3034 (%) Dowanol ® 56.5 56.5 PM (%) Dye C1-1 C1-2 C1-3 C2-1 C2-2 C2-3 Dye A Dye B Dye C Dye A Dye B Dye C 0.04% 0.04% 0.15% 0.04% 0.04% 0.15% Wt. % 0 0 of epoxy compounds according to the invention (*) Haze (%) 0.4 2.0 0.9 0.6 1.0 0.8 Photo- 94 41 87 89 39 75 degra- dation (%)

(22) TABLE-US-00003 Example 1 Epoxy compound (%) EPALLOY ® 9000 37.7 Nacure ® Super A218 (%) 5.7 EFKA ® 3034 (%) 0.1 Dowanol ® PM (%) 56.5 Dye 1-1 1-2 1-3 Dye A Dye B Dye C 0.04% 0.04% 0.15% Wt. % of epoxy 100 compounds according to the invention (*) Haze (%) 0.1 0.1 0.1 Photo-degradation (%) 16 7 13

(23) TABLE-US-00004 Example 2 3 4 Epoxy GE-60 (%) 3.4 10.3 3.4 compound GE-30 (%) 6.9 0 0 UVACure ® 28.1 0 28.1 1500 (%) EPALLOY ® 0 28.1 6.9 9000 (%) Nacure ® Super A218 (%) 5.5 5.8 5.5 EFKA ® 3034 (%) 0.1 0.1 0.1 Dowanol ® PM (%) 56.0 55.7 56.0 Dye 2-1 2-2 3-1 3-2 4-1 4-2 Dye A Dye B Dye A Dye B Dye A Dye B 0.04% 0.04% 0.04% 0.04% 0.04% 0.04% Wt. % of epoxy compounds 73 73 91 according to the invention (*) Haze (%) 0.1 0.1 0.1 0.1 0.1 0.1 Photo-degradation (%) 12 14 5 0 4 1 Oxygen transmission rate 12.4 n.a. n.a. (cm.sup.3 .Math. mil/(100 in.sup.2 .Math. day .Math. atm)) (**) (*) Relative to the total weight of epoxy compounds in the composition. (**) Measured in the absence of dye, for a 10 μm thick coating.

(24) TABLE-US-00005 Example 5 6 7 Epoxy GE-60 (%) 1.7 2.3 2.77 compound GE-30 (%) 3.45 4.66 5.63 UVACure 14.05 18.97 22.93 1500 (%) Glymo (%) 9.8 18.3 11.7 KBE-402 ® (%) 5.1 0 0 Nacure ® Super A218 (%) 2.75 3.71 4.49 EFKA ® 3034 (%) 0.05 0.068 0.082 0.1N HCl (%) 3.3 4.2 2.7 Colloidal silica 31.6 0 0 (30% wt. in MeOH) (%) Dowanol ® PM (%) 28 47.8 49.7 Dye A (%) 0.04 0.04 0.04 Wt. % of epoxy 41 43 53 compounds according to the invention (*) Dry extract weight % of 35 48 56 epoxy compounds according to the invention (**) Haze (%) 0.1 0.1 0.1 Photo-degradation (%) 16 13 11 (*) Relative to the total weight of epoxy compounds in the composition. (**) Relative to the dry extract weight of the composition.

(25) In the lenses having epoxy coatings according to the invention, degradation of the various dyes was reduced to less than 30%, generally less than 20% under the Q-sun test conditions, while lenses having comparative epoxy coatings (with no epoxy compounds comprising a cycloaliphatic or aryl group such as in comparative examples C1-C2 or with such epoxy compounds in an insufficient amount) tend to photo-degrade the same dyes up to 94% under the same conditions.

(26) As can also be seen, all epoxy coatings according to the invention showed low haze (0.1%) with all the dyes, while comparative coatings generally had higher haze levels, up to 2% (comparative example C1). These low haze results demonstrate that there is a good compatibility between the epoxy compounds according to the invention and the dye molecules.

(27) The photo-degradation of the dyes can be further reduced by incorporating in the coating composition at least one UV absorber. For example, when 3% by weight of Tinuvin® 1130 were incorporated in the compositions of examples 5-7, photo-degradation of the ABS-420® dye during the Q-sun test was reduced from 11-16% down to 5-8%.

(28) Another means to reduce the photo-degradation of the dye is to deposit on the epoxy coating according to the invention an antireflection coating acting as an oxygen barrier or an UV shield. Two of such antireflection coatings have been used in examples 3-1B and 3-1C shown in the table below and reduced the photo-degradation of the ABS-420® dye during the Q-sun test from 12% down to 0%:

(29) TABLE-US-00006 Example 3-1 3-1A 3-1B 3-1C Epoxy coating Yes Yes Yes Yes containing 0.04% dye A Primer No Yes Yes Yes Hard coat No Yes Yes Yes Antireflection coating 1 No No Yes No Antireflection coating 2 No No No Yes Haze (%) 0.1 0.1 0.1 0.1 Photo-degradation (%) 12 15 0 0

(30) The lens of example 3-1A is the lens of example 3-1, further coated in this order with a polyurethane-based impact-resistant primer with a thickness of 1 micron (Witcobond latex W-234®), and an abrasion-resistant coating with a thickness of 3 microns obtained by depositing and curing the composition of example 3 of the patent EP 0614957 (comprising γ-glycidoxypropyl trimethoxysilane, dimethyldiethoxysilane, colloidal silica and aluminium acetylacetonate). It can be seen that such coatings hardly alter the resistance to photo-degradation of the dye present in the epoxy coating.

(31) The lens of example 3-1B is the lens of example 3-1A, further coated with the antireflective coating of example 6 of the patent application WO 2008/107325. Said coating was deposited by evaporation under vacuum on the abrasion resistant coating of the lens of example 3-1A. Said antireflection coating comprises a 150 nm thick SiO.sub.2 sub-layer and the stack ZrO.sub.2/SiO.sub.2/ZrO.sub.2/ITO/SiO.sub.2 (respective thicknesses of the layers: 29, 23, 68, 7 and 85 nm). An ITO layer is an electrically conductive layer of indium oxide doped with tin (In.sub.2O.sub.3:Sn).

(32) The lens of example 3-1C is the lens of example 3-1A, further coated with the front face antireflective coating of example 1 of WO 2013/171435, with a 6.5 nm thick indium tin oxide layer interleaved between the 73 nm thick ZrO.sub.2 layer and the 110 nm thick SiO.sub.2 layer.