CURABLE COATING COMPOSITION

Abstract

The present invention relates to a curable coating composition, especially a radiation curable coating composition comprising at least one poly(meth)acrylate compound comprising at least 6 (meth)acrylate groups, at least one unsaturated silane compound, and at least one photoinitiator. Said at least one poly(meth)acrylate compound comprising at least 6 (meth)acrylate groups and said at least one unsaturated silane compound represent at least 95% of the weight of polymerizable compounds present in the composition. Upon radiation-curing, the composition provides an abrasion- and/or scratch-resistant coating.

Claims

1.-15. (canceled)

16. A radiation-curable coating composition comprising: at least one poly(meth)acrylate compound comprising at least 6 (meth)acrylate groups; at least one unsaturated silane compound that is radiation-curable; and at least one photoinitiator; wherein said at least one poly(meth)acrylate compound comprising at least 6 (meth)acrylate groups and said at least one radiation-curable unsaturated silane compound represent at least 95% of the weight of polymerizable compounds present in the composition; and the radiation-curable unsaturated silane compounds are present in an amount higher than or equal to 30% by weight, as compared to the composition total weight.

17. The coating composition of claim 16, wherein the at least one photoinitiator is a free radical generating photoinitiator.

18. The coating composition of claim 16, wherein the composition comprises from 0.1% to 5% photoinitiator by weight relative to the total weight of the composition.

19. The coating composition of claim 16, wherein the photoinitiator is selected from the group consisting of benzophenone compounds, acetophenone compounds, monoacyl and bisacyl phosphine oxides and combinations thereof.

20. The coating composition of claim 16, wherein the poly(meth)acrylate compound is a hexa(meth)acrylate compound.

21. The coating composition of claim 20, wherein the poly(meth)acrylate compound is dipentaerythritol hexaacrylate.

22. The coating composition of claim 16, wherein the radiation-curable unsaturated silane compound is a vinyl silane.

23. The coating composition of claim 22, wherein the radiation-curable unsaturated silane compound is a vinyl alkoxysilane.

24. The coating composition of claim 22, wherein the vinyl silane is a vinyl alkoxysilane selected from the group consisting of vinyl mono-, di- and tri-alkoxysilanes.

25. The coating composition of claim 24, wherein the vinyl silane is vinyltrimethoxysilane.

26. The coating composition of claim 16, wherein the composition further comprises from 0.05 to 1% by weight of a surfactant, as compared to the composition total weight.

27. The coating composition of claim 16, wherein the composition does not comprise any solvent.

28. The coating composition of claim 16, wherein the poly(meth)acrylate compounds are present in an amount higher than or equal to 33% by weight, as compared to the composition total weight.

29. The coating composition of claim 16, wherein the radiation-curable unsaturated silane compounds are present in an amount higher than or equal to 33% by weight, as compared to the composition total weight.

30. An optical article having a substrate coated on at least one main face with an abrasion- and/or scratch-resistant coating obtained by curing a radiation-curable coating composition of claim 16.

31. The optical article of claim 30, wherein the coating has a thickness ranging from 1 to 10 μm.

32. The optical article of claim 30, wherein the optical article is an ophthalmic lens.

33. A method for manufacturing the optical article of claim 30, comprising: providing an optical article comprising a substrate having at least one main face; depositing onto said at least one main face a layer of a radiation-curable coating composition of claim 16; and radiation-curing said composition to form an abrasion- and/or scratch-resistant coating.

34. The method of claim 33, wherein the optical article substrate is selected from the group consisting of thermoplastic, thermoset, and mineral substrates.

Description

EXAMPLES

[0098] 1. Materials and Methods

[0099] The optical articles used in the examples comprised an ORMA® lens substrate from ESSILOR (refractive index of material CR-39: 1.5) or a polycarbonate lens substrate (refractive index: 1.594), having a 65 mm diameter, a power of −2.00 diopters and a thickness of 1.2 mm.

[0100] The ORMA® substrates were hand washed with a mild detergent followed by air drying. The washed and dried substrates were subjected to a chemical treatment consisting of a mild caustic (NaOH) detergent wash with ultrasonication followed by neutralization with dilute (5%) acetic acid solution with ultrasonication followed by a deionized water rinse. The CR-39 lenses were then hand washed with a mild detergent solution, rinsed with deionized water and blown dry with filtered air prior to coating.

[0101] Polycarbonate substrates were first rinsed with deionized water with ultrasonication and then treated with a dilute aminosilane solution followed by a warm water rinse at 60° C. Prior to coating, these substrates were hand washed with a mild detergent solution, rinsed with deionized water and then blown dry with filtered air.

[0102] All radiation cured lenses were coated with a Headway Research bench top spin coater and cured using a Fusion Systems belt conveyor with an ultraviolet/infrared bulb (H+ bulb) under the conditions disclosed in WO 2016/178052.

[0103] The lenses were spin coated with the formulations set forth below and subjected to radiation curing conditions. All coated lenses were allowed to sit overnight prior to further processing.

[0104] The hard coating thicknesses were 5.5-8 μm, except for example C1 (12 μm) and example C4 (3.5 μm).

[0105] 2. Testing Methods

[0106] The thickness of the layers was controlled by viscosity, application speed and spin off speed (for spin coating). For dip coating, thickness was controlled by viscosity and withdrawal speed.

[0107] The haze value H of both the reference and the tested optical article were measured by light transmission as disclosed in WO 2012/173596 utilizing the Haze-Guard Plus hazemeter from BYK-Gardner (a color difference meter) according to the method of ASTM D1003-00 before and after the test has been performed. 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.

[0108] A dry adhesion test, referred to as a crosshatch tape peel adhesion test, was performed on coated articles in accordance with IS™ 02-010, using 3M SCOTCH® no 600 transparent tape, such as disclosed in U.S. Pat. No. 7,476,415 and US 2014/037964.

[0109] Determination of Scratch-Resistance: Hand Steel Wool Test (HSW)

[0110] The HSW test was implemented on the convex side of the lens only. Waiting time of 24 hours was respected to perform the test.

[0111] The lens was manually abraded with a steel wool perpendicularly to fibers direction performing 5 back and forth (with an amplitude from 4 to 5 cm) keeping an index finger constant pressure on the steel wool. Strength pressed on the steel wool can be evaluated with a balance: fix the lens on the balance plate with adhesive tape and press down the lens with the index finger exercising normally strength on the lens. This strength is about 5 Kg during the first way and about 2.5 Kg during the return way. Lenses were visually inspected and noted according to the following table. The higher is the note, the more abraded is the lens. A score of 1 is the best possible score and a score of 5 is the worst.

TABLE-US-00001 Number of scratches >50 11-50 ≤10 Note 5 3 1 Risk level High Acceptable Low

[0112] 3. Results

[0113] The following components were used in the inventive and comparative hard coating compositions. 5 different coating compositions were prepared.

TABLE-US-00002 Component Chemical Type Chemical name Glymo Epoxysilane γ-glycidoxypropyltrimethoxysilane VTMO Unsaturated Vinyltrimethoxysilane silane M-600 Hexaacrylate Dipentaerythritol hexaacrylate GE-30 Aliphatic epoxy Trimethylolpropane triglycidylether SR-238 Diacrylate 1,6-hexanediol diacrylate UVI-6976 Cationic Triarylsulfoniumhexafluoroantimonate photoinitiator UVI-6992 Cationic Triarylsulfoniumhexafluorophosphate photoinitiator Darocur Free-radical 2-hydroxy-2-methy-1-phenyl-propane- 1173 photoinitiator 1-one Irgacure Free-radical Phenylbis(2,4,6- 819 photoinitiator trimethylbenzoyl)phosphine oxide EFKA-3034 Surfactant Fluorinated surfactant

TABLE-US-00003 Example 1 C1 C2 C3 C4 COMPONENT % % % % % Glymo — 44.36  8.67 54.82 — VTMO 47.53  — 43.37  — 54.02 M600 47.53  44.36  43.37  21.93 21.61 GE-30 — — — 10.96 10.80 SR-238 — — — 10.96 10.80 UVI-6976 — 7.32 0.09 0.44 0.07 UVI-6992 — 2.44 0.03 0.15 0.02 Darocur 1173 3.80 1.06 3.47 0.53 2.07 Irgacure 819 0.95 0.27 0.87 0.13 0.52 EFKA-3034 0.20 0.18 0.17 0.07 0.07 TOTAL 100.00  100.00  100.00  100.00 100.00 CR-39 Adhesion Pass Pass Fail Fail Fail (dry) CR-39 Adhesion Pass Pass Fail Fail Fail after tint PC Adhesion Pass Fail Pass Pass Pass (dry) PC Adhesion Pass Fail Pass Pass Pass after tint

[0114] The compositions of comparative examples C1 and C3 do not comprise any unsaturated silane, but rather other acrylic, epoxy, and/or alkoxysilane monomers.

[0115] The compositions of comparative examples C2 and C4 comprise more than 5% by weight of polymerizable compounds that are neither unsaturated silanes nor poly(meth)acrylate compound comprising at least 6 (meth)acrylate groups.

[0116] The formulation of example 1 yielded extraordinarily high scratch resistance results as compared to all other tested hard coating compositions (no scratch was observed after the hand steel wool test) and exhibited good adhesion to both CR-39 and PC substrates when tested after curing (dry) and after being exposed to a BPI® black dye tint bath for 15 minutes at 92° C.

[0117] The compositions of comparative examples C1 to C4 provided coatings having insufficient adhesion to substrates, showing that the presence of an unsaturated silane and at least 95% by weight of poly(meth)acrylates comprising at least 6 (meth)acrylate groups and unsaturated silanes are essential characteristics of the invention.

[0118] One additional testing was performed in order to compare the coating of example 1 with popular commercial or Essilor UV curable coatings used on ophthalmic lenses, using a mechanical steel wool test (000 #steel wool) and a progressive load (increasingly high weights). The lenses had polycarbonate substrates coated on their front faces.

[0119] The difference of haze after testing the coated lenses was measured. The lower the haze, the less scratched is the coating.

[0120] The following hard coats were tested: HT-850 (solvent-borne tintable coating), HBX-1 (solvent-free non tintable coating), EC-1244GS (tintable coating), UVNV (solvent-free tintable coating), ESS-UV (tintable coating). The results are shown below:

TABLE-US-00004 Hard coat Example 1 HT-850 HBX-1 EC-1244GS UVNV ESS-UV Average haze after 0.05 1.3 0.25 0.55 0.9 2.5 mechanical steel wool

[0121] It can be observed that the coating of example 1 has extremely high scratch resistance surpassing that of the best known UV curable hard coats.