Optical article comprising a surfactant-based temporary antifog coating with an improved durability

Abstract

The present invention relates to an optical article comprising a substrate coated with a coating preferably comprising silanol groups on its surface and, directly contacting this coating, an antifog coating precursor coating, said precursor coating preferably having a static contact angle with water of more than 10 and of less than 50 and being obtained through the grafting of at least one organosilane compound possessing a polyoxyalkylene group and at least one silicon atom bearing at least one hydrolyzable group, and is further coated with a film obtained by applying a composition containing at least one surfactant of formula F(CF.sub.2).sub.y(CH.sub.2CH.sub.2O).sub.x+1H (VIII), wherein x is an integer ranging from 1 to 14, y is an integer lower than or equal to 10, compounds of formula (VIII) in which y=6 representing at least 90% by weight by weight, relative to the weight of compounds (VIII) present in the composition, so as to form an antifog coating, having preferably a static contact angle with water lower than or equal to 10.

Claims

1. An optical article comprising a substrate having at least one main surface coated with a first coating and, directly contacting this first coating, a precursor coating of an antifog coating, wherein the coating precursor of the antifog coating is: obtained through the grafting of at least one organosilane compound comprising: a polyoxyalkylene group; and at least one silicon atom bearing at least one hydrolyzable group; and further coated with a film obtained by applying onto the precursor coating a surfactant-containing composition containing at least one surfactant of formula:
F(CF.sub.2).sub.y(CH.sub.2CH.sub.2O).sub.x+1H(VIII), wherein x is an integer ranging from 1 to 14, y is an integer lower than or equal to 10, compounds of formula (VIII) in which y=6 are present in an amount of at least 90% by weight relative to the weight of compounds (VIII) present in said composition, so as to form an antifog coating.

2. The optical article of claim 1, wherein the polyoxyalkylene group comprises less than 80 carbon atoms.

3. The optical article of claim 1, wherein compounds of formula (VIII) in which y=6 are present in an amount of at least 95% by weight relative to the weight of compounds (VIII) present in the composition.

4. The optical article of claim 3, wherein compounds of formula (VIII) in which y=6 are present in an amount of 100% by weight relative to the weight of compounds (VIII) present in the composition.

5. The optical article of claim 1, wherein the antifog coating has a static contact angle with water lower than or equal to 5.

6. The optical article of claim 1, wherein the compounds of formula (VIII), in which x ranges from 1 to 4, are present in an amount of at least 50% by weight, relative to the weight of compounds (VIII) present in the surfactant-containing composition.

7. The optical article of claim 1, wherein the surfactant-containing composition comprises from 0.5 to 15% by weight of surfactants of formula (VIII), relative to the weight of the composition.

8. The optical article of claim 1, wherein the compounds of formula (VIII), in which y is higher than 6, are present in an amount of less than 5% by weight, relative to the weight of compounds (VIII) present in the surfactant-containing composition.

9. The optical article of claim 8, wherein the compounds of formula (VIII), in which y is higher than 6, are present in an amount of 0%, relative to the weight of compounds (VIII) present in the surfactant-containing composition.

10. The optical article of claim 1, wherein the first coating comprises silanol groups on its surface.

11. The optical article of claim 1, wherein the coating precursor of the antifog coating has a thickness lower than or equal to 5 nm.

12. The optical article of claim 1, wherein the coating precursor of the antifog coating has a static contact angle with water of more than 10 and of less than 50.

13. The optical article of claim 1, wherein the organosilane compound is a compound of formula:
R.sup.1Y.sub.mSi(X).sub.3-m(I) wherein the Y groups independently, are monovalent organic groups bound to the silicon through a carbon atom, the X groups independently are hydrolyzable groups, R.sup.1 is a group comprising a polyoxyalkylene group, and m is an integer equal to 0, 1 or 2.

14. The optical article of claim 1, wherein the organosilane compound comprises a polyoxyalkylene group comprising from 5 to 20 carbon atoms.

15. The optical article of claim 1, further defined as an ophthalmic lens.

16. A method for imparting antifog properties to an optical article having at least one main surface, comprising applying onto the main surface a surfactant-containing composition such as defined in claim 1, wherein the optical article comprises a substrate having at least one main surface coated with a precursor coating of an antifog coating, and wherein the coating precursor of the antifog coating is obtained through the grafting of at least one organosilane compound having: a polyoxyalkylene group comprising carbon atoms; and at least one silicon atom bearing at least one hydrolyzable group.

17. The method of claim 16, wherein applying the surfactant-containing composition onto the main surface comprises wiping the main surface with a non-woven tissue comprising a structure which comprises a hydrophilic polymer and a hydrophobic polymer, said tissue being impregnated with the surfactant-containing composition.

18. The method of claim 16, wherein applying the surfactant-containing composition onto the main surface comprises wiping the main surface with a dry microfiber tissue having microfibers comprising polymers comprising polyester units and polyamide units impregnated with the surfactant containing composition.

19. The method of claim 16, wherein the main surface of the optical article has a static contact angle with water of 100 or less before applying the surfactant-containing composition.

20. The method of claim 19, wherein the main surface of the optical article has a static contact angle with water of more than 10 and of less than 50 before applying the surfactant-containing composition.

21. The method of claim 16, wherein the polyoxyalkylene group comprises less than 80 carbon atoms.

Description

EXAMPLES

1. Materials and Optical Articles Used

(1) Silica is used in the form of granules provided by the Optron Inc. company. The organosilane compound used in the examples to form the antifog coating precursor is 2-[methoxy(polyethyleneoxy)propyl]trimethoxysilane comprising from 6 to 9 ethylene oxide units, of formula (III) and with a molecular weight 450-600 g/mol (CAS No.: 65994-07-2. Ref: SIM6492.7, provided by the Gelest, Inc. company).

(2) The lens used comprises a lens substrate in an ORMA material, comprising a polyurethane-based impact-resistant primer with a thickness of about 1 micron, itself provided with an abrasion-resistant coating with a thickness of about 3 microns by depositing and curing a composition such as defined in example 3 of the patent EP 0614957, coated in turn with a five-layer antireflective coating ZrO.sub.2/SiO.sub.2/ZrO.sub.2/ITO/SiO.sub.2 (noted antireflective coating Y) deposited onto the abrasion-resistant coating by evaporation under vacuum of the materials in the order in which they are mentioned (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).

(3) These lenses are treated on both faces according to the methods described hereafter, the concave face being treated before the convex face.

(4) In the examples, the antireflection coating is not submitted to any activating treatment prior to depositing the antifog coating precursor.

2. Vapor Deposition of the Antifog Coating Precursor

(5) In the examples, the deposition is carried out on the antireflective coating Y of a lens by evaporation under vacuum using a Joule effect-based heating source.

(6) The siloxane compound of formula III is poured in a copper capsule (in the absence of any porous material), and this capsule is deposited onto a heating support in conductive tantalum. The evaporating device is a SATIS 1200 DLF or BALZERS BAK apparatus. The evaporation pressure of the siloxane compound of formula III does generally vary from 5.Math.10.sup.6 to 8.Math.10.sup.6 mbar for SATIS 1200 DLF. Once the evaporation is completed, the surface of each lens is rinsed with some soapy water, optionally with isopropyl alcohol, then deionized water and wiped with a Cmoi dry cloth so that the excess of siloxane compound of formula III deposited be removed.

(7) The Cmoi cloth is a cloth provided by the Facol supplier/retailer under the reference Microfibre M 840 S (3040).

3. Application of a Surfactant-Containing Liquid Solution (Temporary Antifog Solution)

(8) 3.1 Preparation of Surfactant Solutions

(9) Two different surfactants were used:

(10) Capstone FS 3100 is the surfactant used for preparing the surfactant solutions of the invention.

(11) Capstone FS 3100 is a surfactant comprising a compound of general formula F(CF.sub.2).sub.y(CH.sub.2CH.sub.2O).sub.x+1H (VIII) for which more than 90% by weight corresponds to the fraction y=6 (even more than 95% by weight), x being an integer ranging from 1 to 14. In other words, Capstone FS3100 is a mixture of compounds having polyethoxylated chains of variable length, but a fluorinated chain of constant length (y=6).

(12) Capstone FS3100 contains trace amounts of compounds of formula (VIII) in which y is higher than 6 (as impurities), which are not detectable through HPLC. The distribution of the ethoxy group as determined by HPLC-MS in the mixture of Capstone FS 3100 compounds is as follows:

(13) TABLE-US-00001 x 1 and 2 3 4 5 6 7 8 9 10 Weight % 28.2 20.5 19.1 14.65 9.35 4.95 2.2 0.85 0.2

(14) Zonyl FSO 100 (from DuPont) is used as a comparative surfactant. Zonyl FSO 100 is a mixture of compounds of formula (VIII) wherein y is equal to 6, 8 and 10 with weight amounts respectively of about 65%, 30% and 5%, and x is an integer ranging from 2 to 13.

(15) A solution is prepared for each surfactant: the surfactant is dissolved in a mixture of deionized water and isopropyl alcohol (IPA), so as to obtain an aqueous solution containing 2.5% by weight of IPA and 6% by weight of surfactant.

(16) 3.2. Deposition of the Solution onto Lenses

(17) The lenses provided with an antifog coating precursor coating prepared under 2 were treated by means of the solutions described under 3.1.

(18) Each solution is applied as follows:

(19) 1. Stir the solution vial before use.

(20) 2. Hold the lens between the thumb and the forefinger and apply 2 drops of the surfactant solution on the center of the convex face of the lens.

(21) 3. Using a clean Cmoi cloth (supplier Facol Microfibre M 840 S (3040), spread the drops with the fingertip over all of the lens surface without rubbing (max 7 seconds).

(22) 4. Perform the same operation with the concave face of the lens.

(23) 5. Allow drying for 5 to 10 seconds and control the lens, as for transmission only, under the ambient light (ceiling light consisting in a neon tube), by keeping the lens at a distance from the eye of from 30 to 50 cm.

(24) 6. Using another clean Cmoi cloth, wipe the edge of the lens.

(25) 7. Remove the white marks which are visible in transmission, the Cmoi cloth being held with the forefinger tip, without strongly rubbing. The lens should be clean and devoid of any white mark over its entire surface.

(26) The method makes it possible to obtain a perfectly transparent ophthalmic lens.

4. Hot Vapor Test

(27) All the vapor tests have been carried out on a 10 lens-panel: 5 pairs (or couples) of lenses, each pair comprising one lens according to the invention (lens treated with the solution with 6% by weight of Capstone FS 3100) and one comparative lens (lens treated with the solution with 6% by weight of Zonyl FSO 100).

(28) Before the test, the lenses are placed for 24 hours in a temperature-regulated environment (20-25 C.) and under 40 to 50% humidity.

(29) For the test, the lenses are placed for 15 seconds above a heated container containing water at 52 C. Immediately after, a visual acuity scale located at a distance of 5 m is observed through the tested lens. The observer evaluates the visual acuity as a function of time and according to following criteria:

(30) 0. No fog, no visual distortion (visual acuity=10/10)

(31) 1. Fog and/or visual distortion allowing a visual acuity>6/10

(32) 2. Fog and/or visual distortion allowing a visual acuity<6/10

(33) In practical terms, to obtain the score 0 or 1, a wearer having a vision of 10/10 and having placed the lens in front of his eye should be able to distinguish the orientation of the E letters on the 6/10 line of the Snellen optotype table placed at a distance of 5 meters.

(34) This test makes it possible to simulate the ordinary living conditions where a wearer leans his face towards a cup of tea/coffee or towards a pan filled with boiling water.

(35) If the lenses obtain a score of 0 or 1, they are submitted to a new vapor test after having controlled under a Waldmann lamp that they were totally dry.

(36) The test is repeated for each couple of lenses until each lens obtains a score 2, meaning that it failed in the vapor test.

(37) The results are given in the following table (Table 1):

(38) TABLE-US-00002 Stress number at Stress number at Stress number at which Zonyl Stress number at which Zonyl which Capstone FSO-100 obtains which Capstone FS- FSO100 obtains the FS-3100 obtains the the score 2 3100 obtains the score 1 score 1 (failure) score 2 (failure) Couple 1 6 34 27 40 Couple 2 10 32 26 38 Couple 3 22 14 28 28 Couple 4 24 30 43 38 Couple 5 21 37 39 39

(39) An improvement in the durability towards vapor test could be noticed with the solution based on Capstone FS-3100 for 3 to 4 of the 5 treated lenses (stress number increased up to 40%), which is particularly important and surprising. For the other lenses, the performances of both surfactants are comparable.

5. Tests Under Winter and Tropical Conditions

(40) These tests were performed using the system for determining the antifog performance of transparent optical articles that is fully described in French patent application n 11.53814 filed on May 4, 2011, and represented on FIG. 1 of said patent application, where it is labeled (20).

(41) A lens passes the test when obtaining a sharpness coefficient N0.6. A lens failed in this test when obtaining a sharpness coefficient N<0.6. The sharpness coefficient N is defined in French patent application n 11.53814.

(42) a) Winter Conditions

(43) In this test, the lenses provided with an antifog coating precursor coating prepared under 2 and further treated as described in 3.2 by means of the solutions described under 3.1 (or with the commercial Defog It solution) were stored for 60 minutes under winter conditions (4 C., 40% humidity) and were then rapidly subjected to normal conditions (20 C., 50% humidity). The results are shown below: (Table 2)

(44) TABLE-US-00003 TABLE 2 Surfactant No wiping 10 wipings 30 wipings Defog it All pass All pass 1 pass, 1 fail Zonyl FSO-100 All pass All pass 1 pass, 1 fail (2 lenses) Capstone FS All pass All pass All pass 3100 (5 lenses)

(45) b) Tropical Conditions

(46) In this test, the lenses provided with an antifog coating precursor coating prepared under 2 and further treated by means of the solutions described under 3.1 (or with the commercial Defog It solution) were stored for 30 minutes under normal conditions (20 C., 45% humidity) and were then rapidly subjected to tropical conditions (30 C., 70% humidity). The results are shown below:

(47) TABLE-US-00004 TABLE 3 Surfactant No wiping 10 wipings 30 wipings 50 wipings Defog it All pass All pass All pass All pass Zonyl FSO- 1 pass, 1 fail All fail All fail All fail 100 (2 lenses) Capstone FS All pass All pass All pass 3 pass, 1 fail 3100 (5 lenses)

(48) It can be concluded from these two series of tests that Capstone FS-3100 (6% by weight) is superior to Zonyl FSO-100 (6% by weight) in terms of antifog performance, and comparable to the Defog It commercial solution.

6. Durability of the Antifogging Effect after a Mechanical Stress (after Application of a Surfactant Solution

(49) This test enables to evaluate the resistance to wiping of the temporary anti-fog solution onto the surface of the lenses. It was carried out on several couple of lenses (2 lenses). The general test protocol is described in 5 of the experimental part of WO 2011/080472.

(50) Each couple of lenses was initially subjected to a series of 5 wipings, then 10, 10, 10, 20, 20 and 20 additional wiping operations were performed. Briefly, a hot vapor test followed by a drying step is carried out between each series of wipings. The test was generally stopped when at least one lens of a couple yielded a low score.

(51) Here, a wiping operation corresponds to one moderately marked rotation of a wiping cloth Cmoi on both faces of the lens (the lens is pressed between the thumb and the forefinger).

(52) The antifog scores (A, B, C or D) correspond to the fog level at the end of each hot vapor test, after implementation of the corresponding number of wiping operations (cumulated number):

(53) A: Homogeneous water film (acuity 10/10)

(54) B: Visual distortion considered as acceptable by the wearer

(55) C: Visual distortion considered as not acceptable by the wearer (heterogeneous water film)

(56) D: Totally diffusing white haze, fine water drops.

(57) The lenses are considered as having successfully passed the durability test if they obtained a score A or B.

(58) Lenses G1 are lenses according to claim 1 having an antireflection coating and a precursor coating of an antifog coating. Lenses G1 are provided with an antifog coating precursor coating prepared under 2 and further treated as described in 3.2 by means of the solutions described under 3.1, or similar solutions with a lower (3% wt) or higher (15% wt) amount of surfactant, keeping the amount of isopropyl alcohol at 2.5%.

(59) Lenses G2 are lenses without antireflection coating and without precursor coating of an antifog coating. Lenses G2 are identical to those described in 1, except that no antireflection coating was deposited onto the abrasion-resistant coating. The solutions described under 3.1 were directly deposited onto said abrasion-resistant coating, as described in 3.2.

(60) The results are shown in the tables hereunder:

(61) TABLE-US-00005 TABLE 4 Antifog score after X (cumulated) Type of Surfactant containing wiping operations with X = Couple n.sup.o lens solution 0 5 15 25 35 55 75 95 1, 2 G1 Zonyl 6% A A A A A A A A G1 Capstone FS3100 3% A A A A A A A A 3 G1 Zonyl 6% A A A A A B C G1 Capstone FS3100 3% A A A A A A A 4 G1 Zonyl 6% A A A B C C G1 Capstone FS3100 3% A A A A A A 5 G1 Zonyl 6% B C C C G1 Capstone FS3100 3% A A A A 6, 7, 8, 9 G1 Zonyl 6% A A A A A A A A G1 Capstone FS3100 6% A A A A A A A A 10 G1 Zonyl 6% A A A A A A A A G1 Capstone FS3100 6% A A A A A A B C 11 G1 Zonyl 6% A A A A A A A A G1 Capstone FS3100 15% A A A A A A A A 12 G1 Zonyl 6% A A A A A A A C G1 Capstone FS3100 15% A A A A A A B C 13 G1 Zonyl 6% A A A A A A A B G1 Capstone FS3100 15% A A A A A A B C 14 G1 Zonyl 6% A A A A A A A B G1 Capstone FS3100 15% A A A A A A A B 15 G1 Zonyl 6% A A A A A A B C G1 Capstone FS3100 15% A A A A A A A C

(62) TABLE-US-00006 TABLE 5 Antifog score after X (cumulated) wiping Type of operations with X = Couple n.sup.o lens Surfactant containing solution 0 5 15 25 35 55 75 1 G2 Zonyl FSO-100 6% A A A A B D G2 Capstone FS3100 6% B B A A B C 2 G2 Zonyl FSO-100 6% A A A A A C D G2 Capstone FS3100 6% A B A A B A A 3 G2 Zonyl FSO-100 6% A A C C G2 Capstone FS3100 6% A A B B 4 G2 Zonyl FSO-100 6% A A A B B D G2 Capstone FS3100 6% A A A A A A 5 G2 Zonyl FSO-100 6% A A A A A D G2 Capstone FS3100 6% A A A A A A

(63) For lenses G1, it can be seen that the durability of antifog performance of Capstone FS-3100 at 3% by weight after a mechanical stress is almost equivalent to that of Zonyl FSO-100 at 6% by weight. Both surfactants exhibit similar antifog performances when used at a weight content of 6%.

(64) For lenses G2, Capstone FS-3100 is more effective than Zonyl FSO-100 at a weight content of 6%. However, the durability of the antifogging effect is lower due to the absence of precursor coating of an antifog coating on lenses G2.

7. Evaluation of Additional Lenses and Cosmetic Aspect of the Lenses

(65) Lens G1 is the lens according to claim 1 that has been defined in 6. Lens G3 is the antifog spectacle lens commercialized by Seiko, which comprises a substrate having a refractive index of 1.6 and a precursor coating of an antifog coating. Lens G4 is the antifog spectacle lens commercialized by Tokai, which comprises a substrate having a refractive index of 1.6 and a precursor coating of an antifog coating.

(66) Lenses G1, G3 and G4 were further treated as described in 3.2 by means of the solution described under 3.1 comprising 6% by weight of Capstone FS-3100.

(67) They were subjected to one hot vapor test such as described previously (without wiping cycles), dried as in 6, and then subjected to additional hot vapor test/drying cycles. Antifog scores were given to the lenses after each hot vapor test. The results are shown in the table below (Table 6).

(68) TABLE-US-00007 Number of hot vapor tests Lens 0 1 2 3 G1 A A A A G3 A A A A G4 A C

(69) All lenses G1, G3 and G4 after having been treated as described in 3.2 by means of the solution described under 3.1 comprising 6% by weight of Capstone FS-3100 exhibit antifogging properties.

(70) Lens G4 does not exhibit a satisfactory antifog effect durability with the Capstone FS-3100 solution. Optical distortion is rapidly observed, and cosmetic aspect after fogging is not acceptable. Indeed, the lens appears whitish after deposition of the surfactant solution. After drying to evaporate the water film formed at the surface of the lens, spots appeared.

(71) Lenses G1 and G3 demonstrate comparable antifog performance with the Capstone FS-3100 solution. However, contrary to lens G1, cosmetic aspect after fogging of lens G3 is not acceptable. After drying to evaporate the water film formed at the surface of the lens, spots appeared.

(72) Lens G1 did not exhibit cosmetic problems, before and after elimination of the excess of the siloxane compound of formula III, even though several wiping cycles are performed in a durability test. After deposition of the surfactant solution, the glide ability of a cloth on the surface of this lens was satisfactory and was the same using Zonyl FSO-100 6% wt rather than Capstone FS-3100 6% wt. Further, the speed of evaporation of the water film formed at the surface of the lens after fogging was the same for both surfactants. In both cases, homogeneity of the water film was the same.