Method for preparing a coated article

Abstract

The present invention provides a method for preparing a coated article, the method comprising: (a) providing a substrate; (b) applying a photopolymerizable coating composition to at least a portion of the substrate, wherein the photopolymerizable coating composition comprises a photopolymerizable anisotropic material and a photoinitiator; (c) ordering the anisotropic material present in the photopolymerizable coating composition; and (d) exposing the ordered photopolymerizable coating composition of (c) to a light-emitting diode light source having a peak emission wavelength ranging from 385 to 460 nanometers to cure the photopolymerizable coating composition. The photoinitiator is capable of being activated at the emission wavelength of the light-emitting diode light source.

Description

Technical Field

[0001] The present invention relates to a method for preparing a coated article, particularly a coated optical article, the coated article using a photopolymerizable coating composition and a light-emitting diode light source for curing the composition. Background Art

[0002] Photochromic coatings (including photochromic-dichroic coatings) for various optical elements are well known. Such photochromic coatings are those having an absorption spectrum for at least visible radiation that varies in response to absorption of at least actinic radiation. Photochromic materials for these photochromic coatings can include thermally reversible photochromic materials and compounds as well as non-thermally reversible photochromic materials and compounds. Thermally reversible photochromic materials / compounds are capable of transitioning from a first state (e.g., a "transparent state") to a second state (e.g., a "colored state") in response to actinic radiation and returning to the first state in response to thermal energy. Non-thermally reversible photochromic compounds / materials are compounds / materials capable of transitioning from a first state (e.g., a "transparent state") to a second state (e.g., a "colored state") in response to actinic radiation and returning to the first state in response to actinic radiation having one or more wavelengths substantially the same as one or more absorptions of the colored state.

[0003] Similarly, photochromic-dichroic compounds / materials are known for use in the above-described photochromic coatings. Such photochromic-dichroic compounds / materials are those having and / or providing both photochromic properties (i.e., having an absorption spectrum for at least visible radiation that varies in response to at least actinic radiation) and dichroic properties (i.e., having a stronger absorption for one of two orthogonally polarized components of at least transmitted radiation than for the other).

[0004] Further, dichroic compounds / materials are those having a stronger absorption for one of two orthogonally polarized components of at least transmitted radiation than for the other. Thus, while a dichroic material can preferentially absorb one of two orthogonally polarized components of transmitted radiation, if the molecules of the dichroic material are not properly positioned or aligned, net linear polarization of the transmitted radiation will not be achieved. Thus, it is generally necessary to properly position or align the molecules of the dichroic material (and photochromic-dichroic material) by orientation with another material to achieve net linear polarization.

[0005] Compositions comprising a photopolymerizable anisotropic material, such as a photopolymerizable liquid crystal material, are known in the art and have been reported. An anisotropic material is a material having at least one property that is different when measured in at least one different direction. Liquid crystal materials, due to their structure, are generally capable of being ordered or aligned so as to exhibit a preferred direction. Thus, liquid crystal molecules can be ordered or aligned by interaction with an external force or another structure such that the long axes of the molecules exhibit an orientation that is generally parallel to a common axis.

[0006] Thermal curing techniques for curing any of the above coatings are well known in the art. However, when used to cure coatings comprising an anisotropic material, such as a liquid crystal material, thermal curing techniques have proven to be unsatisfactory because the thermal curing temperature may disrupt the desired alignment of the anisotropic material during the thermal curing process.

[0007] Photoinduced curing processes using ultraviolet light sources for photochromic and photochromic-dichroic coatings are known. Additionally, it is known that filters can be used to modify the output of a broadband light source during the curing process of photochromic and photochromic-dichroic coatings comprising liquid crystal coatings. Also, the use of narrow-band light-emitting diodes for curing photochromic coatings has been reported.

[0008] Due to the light absorption characteristics of the photochromic and photochromic-dichroic dyes present in the coating, achieving "through-cure" of acceptable photochromic and photochromic-dichroic coatings using the above-mentioned photoinduced curing techniques can be challenging. The photochromic material absorbs the light passing through the coating during the photoinduced curing process, thereby effectively blocking the light absorption of the photoinitiator. Thus, uniform photoinduced curing throughout the coating is inhibited. Additionally, curing photochromic and photochromic-dichroic coatings using ultraviolet light sources typically results in yellowing of the resulting coating.

[0009] In view of the above, there is a desire to provide a method for achieving sufficient through-cure of photochromic and photochromic-dichroic coatings, particularly those comprising an anisotropic material, while avoiding yellowing of the resulting coating and maintaining the alignment of the anisotropic material throughout the curing process. Summary of the Invention

[0010] The present invention relates to a method for preparing a coated article. The method comprises:

[0011] (a) providing a substrate;

[0012] (b) applying a photopolymerizable coating composition to at least a portion of the substrate, the photopolymerizable coating composition comprising:

[0013] (1) a photopolymerizable anisotropic material, and

[0014] (2) Photoinitiator;

[0015] (c) Order the anisotropic material present in the photopolymerizable coating composition; and

[0016] (d) Expose the ordered photopolymerizable coating composition of (c) to a light-emitting diode light source having a peak emission wavelength ranging from 385 to 460 nanometers to cure the photopolymerizable coating composition.

[0017] The photoinitiator is capable of being activated at the peak emission wavelength of the light-emitting diode light source. Description of the Drawings

[0018] Figure 1 Depicts the absorbance spectrum (Spectrum 1) of a mixture of three photochromic-dichroic indeno-fused naphthopyran dyes in the unactivated state in anisole.

[0019] Figure 2 Respectively depict the absorbance spectra (Spectra 2 and 3) of the photoinitiators phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and 2-hydroxy-2-methylpropiophenone. Detailed Description

[0020] As used herein, the articles "a / an" and "the" include plural referents unless otherwise clearly and expressly limited to one referent.

[0021] Unless otherwise specified, all ranges or ratios disclosed herein should be understood to cover any and all subranges or subratios subsumed therein. For example, the recited range or ratio "1 to 10" should be considered to include any and all subranges between the minimum value of 1 and the maximum value of 10 (and including the endpoints); that is, all subranges or subratios starting with a minimum value of 1 or greater and ending with a maximum value of 10 or less, such as but not limited to 1 to 6.1, 3.5 to 7.8, and 5.5 to 10.

[0022] Except in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, etc. used in the specification and claims should be understood to be modified in all instances by the term "about".

[0023] As used herein, the molecular weight values of polymers such as weight-average molecular weight (Mw) and number-average molecular weight (Mn) are determined by gel permeation chromatography using suitable standards (such as polystyrene standards).

[0024] As used herein, the polydispersity index (PDI) value represents the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of a polymer (i.e., Mw / Mn).

[0025] As used herein, the term "polymer" means a homopolymer (e.g., prepared from a single monomer species), a copolymer (e.g., prepared from at least two monomer species), and a graft polymer.

[0026] As used herein, the term "(meth)acrylate" and like terms (such as "(meth)acrylic acid ester") mean methacrylate and / or acrylate. For example, unless otherwise specified herein, the term "(meth)acrylic acid" includes methacrylic acid and / or acrylic acid.

[0027] As used herein, the term "photochromic" and like terms (such as "photochromic compound") mean a compound or material having an absorption spectrum for at least visible radiation that changes in response to absorption of at least actinic radiation. Further, as used herein, the term "photochromic material" means any substance adapted to exhibit photochromic properties (e.g., adapted to have an absorption spectrum for at least visible radiation that changes in response to absorption of at least actinic radiation) and including at least one photochromic compound.

[0028] As used herein, the term "actinic radiation" means electromagnetic radiation capable of causing a response in a material, such as, but not limited to, converting a photochromic material from one form or state to another, as will be discussed further herein.

[0029] As used herein, the term "photochromic material" encompasses thermally reversible photochromic materials and compounds and non-thermally reversible photochromic materials and compounds. As used herein, the term "thermally reversible photochromic compound / material" means a compound / material capable of converting from a first state (e.g., "transparent state") to a second state (e.g., "colored state") in response to actinic radiation and returning to the first state in response to thermal energy. As used herein, the term "non-thermally reversible photochromic compound / material" means a compound / material capable of converting from a first state (e.g., "transparent state") to a second state (e.g., "colored state") in response to actinic radiation and returning to the first state in response to actinic radiation having a wavelength substantially the same as the absorption of the colored state.

[0030] As used herein, the term "photochromic-dichroic" and like terms (such as photochromic-dichroic compound) mean having and / or providing both photochromic properties (i.e., having an absorption spectrum for at least visible radiation that changes in response to at least actinic radiation) and dichroic properties (i.e., having a greater absorption for one of two orthogonally polarized components of at least transmitted radiation than for the other).

[0031] As used herein, for the purpose of modifying the term "state", the terms "first" and "second" are not intended to refer to any particular order or chronological order, but rather to two different conditions or characteristics. For purposes of non-limiting illustration, the first and second states of a photochromic compound can differ in at least one optical property, such as but not limited to absorption of visible radiation and / or UV radiation. Thus, the photochromic compounds of the present invention can have different absorption spectra in each of the first and second states. For example, although not limited herein, the photochromic compounds of the present invention can be transparent in the first state and colored in the second state. Alternatively, the photochromic compounds of the present invention can have a first color in the first state and a second color in the second state.

[0032] As used herein, the term "optical" means related to or associated with light and / or vision. For example, according to various non-limiting embodiments disclosed herein, an optical article or element or device can be selected from: ophthalmic articles, elements and devices, display articles, elements and devices, windows, mirrors, and active and passive liquid crystal cell articles, elements and devices.

[0033] As used herein, the term "ophthalmic" means related to or associated with the eye and vision. Non-limiting examples of ophthalmic articles or elements include corrective and non-corrective lenses (which include single vision or multifocal lenses, and multifocal lenses can be segmented or non-segmented multifocal lenses (such as but not limited to bifocal lenses, trifocal lenses, and progressive lenses)), and other elements for correcting, protecting, or enhancing (cosmetic or otherwise) vision (which include but are not limited to contact lenses, intraocular lenses, magnifying lenses, and protective lenses or goggles).

[0034] As used herein, the term "display" means a visible or machine-readable representation of information in the form of words, numbers, symbols, designs, or pictures. Non-limiting examples of display elements include screens, monitors, and security elements, such as security markings.

[0035] As used herein, the term "window" means an aperture adapted to allow radiation to pass therethrough. Non-limiting examples of windows include transparencies, windshields, filters, shutters, and optical switches for automobiles and airplanes.

[0036] As used herein, the term "mirror" means a surface that specularly reflects a large portion of the incident light.

[0037] As used herein, the term "liquid crystal cell" refers to a structure containing a liquid crystal material that can be ordered. Non-limiting examples of liquid crystal cell elements are liquid crystal displays.

[0038] As used herein, spatial or orientation terms such as "left", "right", "inner", "outer", "above", "below", etc. relate to the various orientations of the present invention that may be further described herein, such as articles and multi-layer articles of the present invention. However, it should be understood that the present invention may assume various alternative orientations to those described herein, and thus such terms should not be considered restrictive.

[0039] As used herein, the terms "formed over", "deposited over", "provided over", "applied over", "residing over", or "positioned over" mean formed, deposited, provided, applied, residing, or positioned on top, but not necessarily in direct (or contiguous) contact with the underlying element, or the surface of the underlying element. For example, a layer "placed over a substrate" does not exclude the presence of one or more other layers, coatings, or films of the same or different composition located between the layer so placed or formed and the substrate.

[0040] All documents mentioned herein (such as but not limited to published patents and patent applications), and unless otherwise specified, are hereby incorporated by reference in their entirety.

[0041] As used herein, the term "alkyl" means straight-chain or branched-chain alkyl, such as but not limited to straight-chain or branched-chain C1-C 25 alkyl, or straight-chain or branched-chain C1-C 10 alkyl, or straight-chain or branched-chain C2-C 10 alkyl. Representative alkyls may include but are not limited to methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, and decyl.

[0042] As used herein, the term "cycloalkyl" means a suitably cyclic group, such as but not limited to C3-C 12A cycloalkyl group (including but not limited to cyclic C5-C7 alkyl groups). Examples of cycloalkyl groups include those previously listed herein. As used herein, the term "cycloalkyl" also includes: bridged polycycloalkyl (or bridged polycyclic alkyl), such as but not limited to bicyclo[2.2.1]heptyl (or norbornyl) and bicyclo[2.2.2]octyl; and fused polycycloalkyl (or fused polycyclic alkyl), such as but not limited to octahydro-1H-indenyl, and decahydronaphthyl.

[0043] As previously mentioned, the present invention relates to a method for preparing a coated article, the method comprising:

[0044] (a) providing a substrate;

[0045] (b) applying a photopolymerizable coating composition to at least a portion of the substrate, the photopolymerizable coating composition comprising:

[0046] (1) a photopolymerizable anisotropic material, and

[0047] (2) a photoinitiator;

[0048] (c) ordering the anisotropic material present in the photopolymerizable coating composition; and

[0049] (d) exposing the ordered photopolymerizable coating composition of (c) to a light-emitting diode light source having a peak emission wavelength in the range from 385 to 460 nanometers to cure the photopolymerizable coating composition,

[0050] wherein the photoinitiator is capable of being activated at the peak emission wavelength of the light-emitting diode light source.

[0051] Non-limiting examples of suitable substrates for use in the method of the present invention include substrates formed from organic materials, inorganic materials, or combinations thereof (e.g., composites). Specific, non-limiting examples of organic materials that can be used to form the substrates disclosed herein include polymeric materials, such as homopolymers and copolymers, prepared from the monomers and monomer mixtures disclosed in U.S. Patent No. 5,962,617 and U.S. Patent No. 5,658,501 from column 15, line 28 to column 16, line 17, the disclosures of these U.S. patents being hereby specifically incorporated by reference.

[0052] For example, such polymeric materials can be thermoplastic or thermosetting polymeric materials, can be transparent or optically clear, and can have any refractive index desired. Non-limiting examples of such disclosed monomers and polymers include: polyol (allyl carbonate) monomers, such as allyl diglycol carbonate, e.g., diethylene glycol bis(allyl carbonate), which is sold by PPG Industries, Inc. under the trademark CR-39; polyurea-polyurethane polymers, which are prepared, for example, by the reaction of a polyurethane prepolymer with a diamine curing agent, and a composition for one such polymer is sold by PPG Industries under the trademark TRIVEX; polyol (meth)acryloyl-terminated carbonate monomers; diethylene glycol dimethacrylate monomers; ethoxylated phenol methacrylate monomers; diisopropenylbenzene monomers; ethoxylated trimethylolpropane triacrylate monomers; ethylene glycol dimethacrylate monomers; poly(ethylene glycol) dimethacrylate monomers; urethane acrylate monomers; poly(ethoxylated bisphenol A dimethacrylate); poly(vinyl acetate); poly(vinyl alcohol); poly(vinyl chloride); poly(vinylidene chloride); polyethylene; polypropylene; polyurethane; polythiourethane; thermoplastic polycarbonate, such as a carbonate-linked resin derived from bisphenol A and phosgene, and one such material is sold under the trademark LEXAN; polyester, such as a material sold under the trademark MYLAR; poly(ethylene terephthalate); polyvinyl butyral; poly(methyl methacrylate) (such as a material sold under the trademark PLEXIGLAS), and polymers prepared by reacting polyfunctional isocyanates with polythiol or polycyclic sulfide monomers, homopolymerized or copolymerized and / or terpolymerized with polythiols, polyisocyanates, polyisothiocyanates, and optionally ethylenically unsaturated monomers or vinyl monomers containing halogenated aromatics. Copolymers of such monomers and blends of the described polymers and copolymers with other polymers are also contemplated, e.g., to form block copolymers or interpenetrating network products.

[0053] Although not limited herein, the substrate can be an optical substrate, such as an ophthalmic substrate. As used herein, the term "ophthalmic substrate" refers to lenses, partially formed lenses, and lens blanks. Non-limiting examples of organic materials suitable for use in forming an ophthalmic substrate can include, but are not limited to, polymers recognized in the art as being useful as ophthalmic substrates, such as organic optical resins for preparing optically clear castings for optical applications, such as ophthalmic lenses.

[0054] Other non-limiting examples of organic materials suitable for use in forming a substrate can include both synthetic and natural organic materials, including but not limited to: opaque or translucent polymeric materials, natural and synthetic textiles, and cellulosic materials (such as paper and wood).

[0055] Non-limiting examples of inorganic materials suitable for use in a substrate for the methods of the present invention may include glass, minerals, ceramics, and metals. For example, the substrate may include glass. Additionally, the substrate may have a reflective surface, such as a polished ceramic substrate, a metal substrate, or a mineral substrate. A reflective coating or layer may be deposited or otherwise applied to the surface of an inorganic or organic substrate to make it reflective or enhance its reflectivity.

[0056] Further, as discussed below, the substrate may have a protective coating on its outer surface, such as, but not limited to, an abrasion-resistant coating, such as a "hard coating". Thus, as used herein, the term "substrate" includes a substrate having a protective coating (such as, but not limited to, an abrasion-resistant coating) on one or more of its surfaces.

[0057] Still further, the substrate may be an uncolored, colored, linearly polarized, circularly polarized, elliptically polarized, photochromic, or colored photochromic substrate. As used herein with respect to a substrate, the term "uncolored" means a substrate that is substantially free of colorant additives (such as, but not limited to, conventional dyes) and has an absorption spectrum for visible radiation that does not vary significantly in response to actinic radiation. Further, with respect to a substrate, the term "colored" means a substrate that has a colorant additive (such as, but not limited to, conventional dyes) and an absorption spectrum for visible radiation that does not vary significantly in response to actinic radiation.

[0058] As used herein, the term "linearly polarized" with respect to a substrate refers to a substrate that is adapted for linearly polarized radiation. As used herein, the term "circularly polarized" with respect to a substrate refers to a substrate that is adapted for circularly polarized radiation. As used herein, the term "elliptically polarized" with respect to a substrate refers to a substrate that is adapted for elliptically polarized radiation. As used herein, the term "photochromic" with respect to a substrate refers to a substrate that has an absorption spectrum for visible radiation that varies in response to at least actinic radiation. Further, as used herein with respect to a substrate, the term "colored photochromic" means a substrate that contains a colorant additive as well as a photochromic material and has an absorption spectrum for visible radiation that varies in response to at least actinic radiation. Thus, for example and without limitation, a colored photochromic substrate may have a first color characteristic of the colorant and a second color characteristic of a combination of the colorant and the photochromic material when exposed to actinic radiation.

[0059] Generally, the substrate (a) comprises a polymeric material selected from the group consisting of polycarbonate, polycyclic olefin, polyurethane, poly(urea)urethane, polythiourethane, polythi(urea)urethane, poly(allyl carbonate) polymer, cellulose acetate, diacetate cellulose, triacetate cellulose, cellulose acetate propionate, cellulose acetate poly(vinylidene chloride), poly(ethylene terephthalate), polyester, polysulfone, polyolefin, copolymers thereof, and mixtures thereof.

[0060] As previously mentioned, in the method of the present invention, a photopolymerizable coating composition is applied to at least a portion of the surface of a substrate. The photopolymerizable coating composition comprises (1) a photopolymerizable anisotropic material, and (2) a photoinitiator.

[0061] As used herein, the term "anisotropic" means having at least one property that has a different value when measured in at least one different direction. Thus, an "anisotropic material" is a material having at least one property that has a different value when measured in at least one different direction. Non-limiting examples of anisotropic materials suitable for use in the photopolymerizable coating compositions disclosed herein include liquid crystal materials, such as but not limited to photopolymerizable liquid crystal materials.

[0062] Liquid crystal materials, due to their structure, are generally capable of being ordered or aligned so as to exhibit a substantially direction. More specifically, since liquid crystal molecules have a rod-like or disc-like structure, a rigid major axis, and a strong dipole, the liquid crystal molecules can be ordered or aligned by interacting with an external force or another structure so that the major axis of the molecules exhibits an orientation substantially parallel to a common axis. For example, although not limited herein, it is possible to align the molecules of a liquid crystal material with a magnetic field, an electric field, linearly polarized infrared radiation, linearly polarized ultraviolet radiation, linearly polarized visible radiation, or a shear force. It is also possible to align liquid crystal molecules with an oriented surface. That is, liquid crystal molecules can be applied, for example, by rubbing, grooving, or photoalignment methods to an already oriented surface and then aligned so that the major axis of each liquid crystal molecule in the liquid crystal molecules exhibits an orientation substantially parallel to the orientation of the substantially direction of the surface.

[0063] Non-limiting examples of liquid crystal materials suitable for use in the photopolymerizable coating compositions may include liquid crystal polymers, liquid crystal prepolymers, liquid crystal monomers, and liquid crystal mesogens. As used herein, the term "prepolymer" means a partially polymerized material.

[0064] Liquid crystal monomers suitable for use in the photopolymerizable coating compositions may include monofunctional liquid crystal monomers as well as polyfunctional liquid crystal monomers. Further, the liquid crystal monomers may be photopolymerizable liquid crystal monomers. As used herein, the term "photopolymerizable" means a material that can crosslink upon exposure to actinic radiation, such as a monomer, prepolymer, or polymer. For example, photopolymerizable liquid crystal monomers may include those liquid crystal monomers that can crosslink upon exposure to ultraviolet radiation and / or visible radiation, with or without a polymerization initiator.

[0065] Non-limiting examples of photopolymerizable liquid crystal monomers suitable for use in a photopolymerizable coating composition can include liquid crystal monomers having a functional group selected from the following: acrylate, methacrylate, allyl, allyl ether, alkyne, amino, anhydride, epoxide, hydroxide, isocyanate, blocked isocyanate, siloxane, thiocyanate, thiol, urea, vinyl, vinyl ether, and blends thereof.

[0066] Photopolymerizable liquid crystal polymers and prepolymers suitable for use in a photopolymerizable coating composition can include main-chain liquid crystal polymers and prepolymers and side-chain liquid crystal polymers and prepolymers. In the main-chain liquid crystal polymers and prepolymers, rod-like or disc-like liquid crystal mesogens are mainly located within the polymer main chain. In the side-chain polymers and prepolymers, rod-like or disc-like liquid crystal mesogens are mainly located within the polymer side chains.

[0067] Non-limiting examples of photopolymerizable liquid crystal polymers and prepolymers suitable for use in a photopolymerizable coating composition can include, but are not limited to, main-chain and side-chain polymers and prepolymers having a functional group selected from the following: acrylate, methacrylate, alkyne, epoxide, thiol, and blends thereof.

[0068] Liquid crystal mesogens suitable for use in a photopolymerizable coating composition can include thermotropic liquid crystal mesogens and lyotropic liquid crystal mesogens. Further, non-limiting examples of liquid crystal mesogens suitable for use in combination with the various non-limiting embodiments disclosed herein include calamitic (or rod-like) liquid crystal mesogens and discotic (or disc-like) liquid crystal mesogens.

[0069] Mixtures of any of the above liquid crystal materials can be used.

[0070] Based on the total weight of the solids present in the photopolymerizable coating composition, the photopolymerizable anisotropic material can be present in the photopolymerizable coating composition in an amount ranging from 50 to 99.8 weight percent, such as 70 to 99.5 weight percent or 85 to 99 weight percent.

[0071] As previously mentioned, the photopolymerizable coating composition further comprises a photoinitiator. One or more suitable photoinitiators can include those selected from the group consisting of phosphine-based photoinitiators, benzoyl-based photoinitiators, substituted benzoyl-based photoinitiators, and mixtures thereof.

[0072] Non-limiting examples of suitable phosphine-based photoinitiators and benzoyl-based photoinitiators can include phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, (2,4-dipentyloxyphenyl)bis(2,4,6-trimethylbenzoyl)phosphine oxide, (4-(dimethylamino)phenyl)bis(2,4,6-trimethylbenzoyl)phosphine oxide, (2,6-dimethylbenzoyl)diphenylphosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, (2,6-dichlorobenzoyl)diphenylphosphine oxide, (2,6-dimethoxybenzoyl)diphenylphosphine oxide, (2,4,6-trimethoxybenzoyl)diphenylphosphine oxide, (4-methoxybenzoyl)diphenylphosphine oxide, (4-(dimethylamino)benzoyl)diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)(2,4,4-trimethylpentyl)phosphine oxide, bis(2,6-dimethylbenzoyl)(2,4,4-trimethylpentyl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)(2,4,4-trimethylpentyl)phosphine oxide, bis(2,6-dichlorobenzoyl)(2,4,4-trimethylpentyl)phosphine oxide, bis(2,6-dichlorobenzoyl)phenylphosphine oxide, bis(2,6-dichlorobenzoyl)(4-propylphenyl)phosphine oxide, dibenzoyldiethylgermane, and ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate.

[0073] Based on the total weight of the solids present in the photopolymerizable coating composition, the photoinitiator can be present in the photopolymerizable coating composition in an amount ranging from 10 to 0.1 weight percent, such as 5 to 0.3 weight percent or 2 to 0.5 weight percent. It should be noted herein that the photoinitiator present in the photopolymerizable coating composition should be capable of being activated at the peak emission wavelength of the light-emitting diode light source, as discussed in detail below.

[0074] For certain applications, the photopolymerizable coating composition can further comprise a material selected from the group consisting of photochromic compounds, dichroic compounds, photochromic-dichroic compounds, and mixtures thereof.

[0075] As previously mentioned, as used herein, the term "photochromic material" includes both thermally reversible photochromic compounds and non-thermally reversible (or photochemically reversible) photochromic compounds. Generally, although not limited herein, when two or more photochromic materials are used in combination with each other or in combination with photochromic-dichroic compounds (such as those described below), various materials can be selected to complement each other to produce the desired color or hue. For example, mixtures of photochromic compounds can be used to obtain certain activated colors, such as near-neutral gray or near-neutral brown. See, e.g., U.S. Patent No. 5,645,767, column 12, line 66 to column 13, line 19, the disclosure of which is incorporated herein by specific reference, which patent describes the parameters defining neutral gray and brown.

[0076] Photochromic materials can include any of a variety of organic and inorganic photochromic materials. One or more photochromic materials can include, but are not limited to, materials of the following classes: chromenes, such as naphthopyrans, benzopyrans, indonaphthopyrans, phenanthropyran, or mixtures thereof; spiropyrans, such as spiro(benzindoline)naphthopyran, spiro(indoline)benzopyran, spiro(indoline)naphthopyran, spiro(indoline)quinopyran, and spiro(indoline)pyran; oxazines, such as spiro(indoline)naphthoxazine, spiro(indoline)pyridobenzoxazine, spiro(benzindoline)pyridobenzoxazine, spiro(benzindoline)naphthoxazine, and spiro(indoline)benzoxazine; mercuric dithizonate, fulgides, fulgimides, and mixtures of such photochromic compounds.

[0077] Such photochromic materials and complementary photochromic materials are described in U.S. Patent Nos. 4,931,220, column 8, line 52 to column 22, line 40; 5,645,767, column 1, line 10 to column 12, line 57; 5,658,501, column 1, line 64 to column 13, line 17; 6,153,126, column 2, line 18 to column 8, line 60; 6,296,785, column 2, line 47 to column 31, line 5; 6,348,604, column 3, line 26 to column 17, line 15; and 6,353,102, column 1, line 62 to column 11, line 64, the disclosures of the above patents being incorporated herein by reference. Spiropyrans are also described in the text "Techniques in Chemistry" , Volume III, "Photochromism", Chapter 3, Glenn H. Brown, editor, John Wiley and Sons, Inc., New York, 1971.

[0078] Suitable photochromic materials may also include polymerizable photochromic materials, such as polymerizable naphthoxazines disclosed in U.S. Patent No. 5,166,345, column 3, line 36 to column 14, line 3; polymerizable spirobenzopyrans disclosed in U.S. Patent No. 5,236,958, column 1, line 45 to column 6, line 65; polymerizable spirobenzopyrans and spirobenzothiopyrans disclosed in U.S. Patent No. 5,252,742, column 1, line 45 to column 6, line 65; polymerizable fulgides disclosed in U.S. Patent No. 5,359,085, column 5, line 25 to column 19, line 55; polymerizable bianthraquinodimethanes disclosed in U.S. Patent No. 5,488,119, column 1, line 29 to column 7, line 65; polymerizable spirooxazines disclosed in U.S. Patent No. 5,821,287, column 3, line 5 to column 11, line 39; polymerizable polyalkoxylated naphthopyrans disclosed in U.S. Patent No. 6,113,814, column 2, line 23 to column 23, line 29; and polymerizable photochromic compounds disclosed in WO 97 / 05213 and U.S. Patent No. 6,555,028, column 1, line 16 to column 24, line 56. The disclosures of the above patents regarding polymerizable photochromic materials are incorporated herein by reference.

[0079] Other suitable photochromic materials may include organometallic dithizonates, e.g., (arylazo)-thioformic acid aryl hydrazides, e.g., mercuric dithizonate described in, e.g., U.S. Patent No. 3,361,706, column 2, line 27 to column 8, line 43; and fulgides and fulgimides, e.g., 3-furyl and 3-thienyl fulgides and fulgimides, which are described in U.S. Patent No. 4,931,220, column 1, line 39 through column 22, line 41, the disclosures of these patents being incorporated herein by reference.

[0080] Further photochromic materials may include organic photochromic materials that are resistant to the action of polymerization initiators in use. Such organic photochromic materials include photochromic compounds mixed with resinous materials that have been formed into particles and encapsulated in metal oxides, as described in U.S. Patent Nos. 4,166,043 and 4,367,170, column 1, line 36 to column 7, line 12, the disclosures of these patents being incorporated herein by reference.

[0081] As previously mentioned, as used herein, the term "dichroic" means that the absorption of one of at least two orthogonally plane-polarized components of the transmitted radiation is stronger than that of the other. Thus, although a dichroic material can preferentially absorb one of the two orthogonally plane-polarized components of the transmitted radiation, if the molecules of the dichroic material are not properly positioned or aligned, a net linear polarization of the transmitted radiation cannot be achieved. That is, due to the random positioning of the molecules of the dichroic material, the selective absorption of individual molecules will cancel each other out such that a net linear polarization effect or an overall linear polarization effect cannot be achieved. Therefore, it is generally necessary to properly position or align the molecules of the dichroic material by orientation with another material to achieve a net linear polarization.

[0082] Non-limiting examples of suitable conventional dichroic compounds include azomethines, indigos, thioindigos, merocyanines, indans, quinophthalone dyes, perylenes, phthaloperines, tribenzodioxazines, indoloquinoxalines, imidazo-triazines, tetrazines, azo and (poly)azo dyes, benzoquinones, naphthoquinones, anthraquinones and (poly)anthraquinones, anthrapyrimidinones, iodine and iodates. In addition, the dichroic material can be a polymerizable type dichroic compound. That is, the dichroic material can include at least one group capable of being polymerized (i.e., a "polymerizable group"). For example, although not limited herein, the dichroic compound can have at least one alkoxy, polyalkoxy, alkyl or polyalkyl substituent terminated with at least one polymerizable group.

[0083] As previously mentioned, as used herein, the terms "photochromic-dichroic" and similar terms (such as photochromic-dichroic compounds) mean having and / or providing both photochromic properties (i.e., having an absorption spectrum for at least visible radiation that varies in response to at least actinic radiation) and dichroic properties (i.e., the absorption of one of at least two orthogonally plane-polarized components of the transmitted radiation is stronger than that of the other).

[0084] Examples of photochromic-dichroic compounds suitable for use in a photopolymerizable coating composition useful in the methods of the present invention can include, but are not limited to, those detailed in U.S. Patent 7,256,921B2, columns 19 line 3 to column 66 line 60, the disclosure of which is incorporated herein by reference.

[0085] If included, the photochromic compound and / or the photochromic-dichroic compound are typically present in the photopolymerizable coating composition in an amount (which is referred to as the photochromic amount) that is at least sufficient to provide the desired level of photochromic properties to the article prepared from the composition. When used, based on the total solids weight of the photopolymerizable coating composition (including the weight of one or more photochromic compounds and / or photochromic-dichroic compounds and including the recited values), the amount of one or more photochromic compounds and / or one or more photochromic-dichroic compounds present in the curable composition can range from 0.001 weight percent to 40 weight percent, or from 0.01 to 30 weight percent, or from 0.1 to 20 weight percent, or from 1 to 15 weight percent.

[0086] The photopolymerizable coating composition used in the method of the present invention can optionally contain additives such as, but not limited to, waxes for flow and wetting; plasticizers, thermoplastics, flow control agents such as poly(2-ethylhexyl) acrylate; antioxidants, including mesogenic antioxidants; hindered amine light stabilizers, including mesogenic hindered amine light stabilizers; ultraviolet (UV) light absorbers, including mesogenic UV absorbers; ultraviolet stabilizers; surfactants; adhesion promoters; fixed tone dyes; and solvents. Examples of useful antioxidants include, but are not limited to, those commercially available from BASF under the trademarks IRGANOX and TINUVIN. When used, based on the total solids weight of the photopolymerizable coating composition (excluding solvents), these optional additives can be present in an amount up to 30 weight percent.

[0087] Commercially available plasticizer additives include, but are not limited to, Benzoflex 9-88, Benzoflex 9-88SG, Enhancer 400, Admex 6995, Admex 6187, Admex 760, and Admex 770 commercially available from Eastman Chemical Company; polybutadiene-based plasticizers can include Polyvest 130, Polyvest MA75, Polyvest HT, Polyvest EP ST M, and Polyvest EP STE-100 commercially available from Evonik; polymeric plasticizers can include D-1116, G-1701MU, G-1643, G-1652MU, G-1657MS, G-1657VS, G-1701MU, and MD-1648 commercially available from Kraton Corporation. Commercially available thermoplastic polyurethane (TPU) additives can also be used.

[0088] As mentioned above, the photopolymerizable coating composition may further comprise one or more fixed-tone dyes. As used herein, the terms "fixed-tone dye" and related terms such as "fixed-colorant", "static colorant", "fixed dye", and "static dye" mean dyes that are non-photosensitive materials and do not physically or chemically respond to electromagnetic radiation with respect to the color visually observed. As used herein, the terms "fixed-tone dye" and related terms do not include photochromic compounds and can be distinguished from photochromic compounds. As used herein, the term "non-photosensitive material" means a material that does not physically or chemically respond to electromagnetic radiation related to the color visually observed, which includes but is not limited to fixed-tone dyes.

[0089] One or more fixed-tone dyes may be present in the photopolymerizable coating composition of the present invention, and the purposes include but are not limited to providing the following to the coated article prepared from the photopolymerizable coating composition: at least one basic (or first) color characteristic of the fixed-tone dye when the photochromic compound (if used) is not activated; and optionally, a second color characteristic of the combination of the fixed-tone dye and the photochromic compound when activated (such as by exposure to actinic radiation). The optional fixed-tone dye of the photopolymerizable coating composition may comprise at least one of the following: azo dyes, anthraquinone dyes, xanthene dyes, azime dyes, iodine, iodide salts, polyazo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes, and polyene dyes.

[0090] The photopolymerizable coating composition of the present invention may include solvents such as those selected from water, organic solvents, and combinations thereof. The types of organic solvents that may be present in the curable photochromic composition of the present invention include but are not limited to ketones such as acetone and methyl ethyl ketone; ethers such as dimethyl ether and methyl ethyl ether; cyclic ethers such as tetrahydrofuran and dioxane; esters such as ethyl acetate, 2-butoxyethyl acetate, ethyl lactate, ethylene carbonate, and propylene carbonate, especially 1,2-propylene glycol cyclic carbonate; nitrogen-containing cyclic compounds such as pyrrolidone, N-methyl-2-pyrrolidone, 1-butylpyrrolidin-2-one, and 1,3-dimethyl-2-imidazolidinone; sulfur-containing compounds such as dimethyl sulfoxide and tetramethylene sulfone; aromatic compounds such as toluene, xylene, anisole, and butyl benzoate; and mixtures of aromatic compounds such as but not limited to Aromatic100Fluid (which is a commercially available mixture of C9-C 10 dialkylbenzenes and trialkylbenzenes), or Aromatic 150 (which is a commercially available C9-C 11mixture of alkylbenzenes).

[0091] One or more solvents may be present in the curable composition of the present invention in an amount from 5 to 95 weight percent, or from 15 to 80 weight percent, or 20 to 60 weight percent, in each case based on the total weight of the photopolymerizable coating composition (including the weight of the solvent).

[0092] Any of the photopolymerizable coating compositions in the above-mentioned photopolymerizable coating compositions can be applied to a substrate by any coating application technique known and recognized in the art. For example, the photopolymerizable coating composition can be applied by an application method selected from the group consisting of: spin coating, spraying, ultrasonic spraying, curtain coating, dip coating, roll coating, flow coating, wire coating, overlaying, and combinations thereof.

[0093] Once applied to a substrate, the photopolymerizable anisotropic materials present in the photopolymerizable coating composition can be at least partially ordered. The photopolymerizable anisotropic materials present in the photopolymerizable coating composition can be at least partially ordered by exposure to a magnetic field, an electric field, linearly polarized infrared radiation, linearly polarized ultraviolet radiation, linearly polarized visible radiation, shear force, or a combination thereof.

[0094] Alternatively or additionally, the photopolymerizable anisotropic materials can be at least partially ordered by aligning at least a portion of the anisotropic materials with another material or structure. For example, the photopolymerizable anisotropic materials can be at least partially ordered by aligning the anisotropic materials with an alignment layer (or alignment facility) (such as, but not limited to, those alignment layers described in further detail below).

[0095] By ordering at least a portion of the photopolymerizable anisotropic materials, at least a portion of the photochromic-dichroic dye and / or the dichroic dye as a component of the photopolymerizable coating composition is at least partially aligned. Although not necessary, the photochromic-dichroic dye can be at least partially aligned when in the activated state.

[0096] Photochromic-dichroic dyes and photopolymerizable anisotropic materials can be aligned and ordered during the application of the anisotropic layer. For example, a photopolymerizable coating composition comprising a photopolymerizable anisotropic material can be applied using a coating technique that introduces a shear force to the anisotropic material during application such that the anisotropic material becomes at least partially ordered, generally parallel to the direction of the applied shear force. An example of a coating process that can introduce at least sufficient shear force is a curtain coating process. The shear force can cause at least a portion of the anisotropic material to be ordered in a general direction that is substantially parallel to the direction of movement of the surface. As discussed above, by ordering at least a portion of the anisotropic material in this manner, at least a portion of the photochromic-dichroic dye and / or the dichroic dye can be aligned. Additionally and optionally, at least a portion of the photochromic-dichroic dye can be aligned in the activated state by exposing at least a portion of the photochromic-dichroic dye to actinic radiation during the curtain coating process in order to convert the photochromic-dichroic dye to the activated state.

[0097] The photopolymerizable anisotropic material can be aligned and ordered after the photopolymerizable coating composition is applied to a substrate. For example, the photopolymerizable coating composition can be spin-coated on at least a portion of the substrate. Thereafter, at least a portion of the photopolymerizable anisotropic material can be ordered, for example, by exposing the anisotropic material to a magnetic field, an electric field, linearly polarized ultraviolet radiation, linearly polarized infrared radiation, linearly polarized visible radiation, and / or a shear force. Alternatively or additionally, the photopolymerizable anisotropic material can be at least partially ordered by its alignment with another material or structure, such as an alignment layer.

[0098] As used herein, the term "alignment layer" means a layer that can facilitate the orientation of one or more other structures that are directly and / or indirectly exposed to at least a portion thereof. As used herein, the term "order" means to bring into a proper arrangement or position, such as by aligning with another structure or material, or by some other force or action. Thus, as used herein, the term "ordering" encompasses both contact methods of ordering a material (such as by aligning with another structure or material) and non-contact methods of ordering a material (such as by exposure to an external force or action). The term "ordering" also encompasses combinations of contact methods and non-contact methods.

[0099] For example, a photochromic-dichroic dye or a dichroic dye that is at least partially aligned by interacting with an alignment layer can be at least partially aligned such that the major axis of the photochromic-dichroic dye (when in the activated state) and / or the dichroic dye is substantially parallel to at least a first general direction of the alignment layer. The photochromic-dichroic dye that is at least partially aligned by interacting with the alignment layer can be bound to or reacted with the alignment layer. As used herein with respect to the ordering or alignment of a material or structure, the term "general direction" refers to the major arrangement or orientation of the material, compound, or structure. Further, those skilled in the art will understand that a material, compound, or structure can have a general direction even if there are some variations in the arrangement of the material, compound, or structure, provided that the material, compound, or structure has at least one major arrangement.

[0100] The alignment layer can have at least a first general direction. For example, the alignment layer can include a first ordered region having a first general direction and at least one second ordered region adjacent to the first ordered region, the second ordered region having a second general direction different from the first general direction. Further, the alignment layer can have a plurality of regions, each region having the same or a different general direction from the remaining regions, so as to form a desired pattern or design. The alignment layer can include, for example, a coating that includes an at least partially ordered alignment medium, an at least partially ordered polymer sheet, an at least partially treated surface, a Langmuir-Blodgett film, and combinations thereof.

[0101] The alignment layer can include a coating that includes an at least partially ordered alignment medium. Examples of suitable alignment media that can be used in combination with the alignment layer include, but are not limited to, photoalignment materials, rubbed alignment materials, and liquid crystal materials. Methods for ordering at least a portion of the alignment medium are described in further detail below.

[0102] The alignment medium of the alignment layer can be a liquid crystal material, and the alignment layer can be referred to as a liquid crystal alignment layer. Liquid crystal materials, due to their structure, are generally capable of being ordered or aligned so as to exhibit a general direction. Liquid crystal materials suitable for use in preparing the alignment layer can include any of those previously discussed with respect to photopolymerizable anisotropic materials.

[0103] Examples of photo-aligning materials that may be included in the alignment layer include, but are not limited to, photo-alignable polymer networks. More specific examples of photo-alignable polymer networks include, but are not limited to, azobenzene derivatives, cinnamic acid derivatives, coumarin derivatives, ferulic acid derivatives, and polyimides. For some embodiments, the alignment layer may include at least partially ordered photo-alignable polymer networks selected from: azobenzene derivatives, cinnamic acid derivatives, coumarin derivatives, ferulic acid derivatives, and / or polyimides. Examples of cinnamic acid derivatives that may be included in the alignment layer include, but are not limited to, polyvinyl cinnamate and polyvinyl p-methoxycinnamate.

[0104] As used herein, the term "rubbing alignment material" means a material that can be at least partially ordered by rubbing at least a portion of the surface of the material against another suitably textured material. For example, a rubbing alignment material can be rubbed with a suitably textured cloth or velvet brush. Examples of rubbing alignment materials that may be included in the alignment layer include, but are not limited to, (poly)imides, (poly)siloxanes, (poly)acrylates, and (poly)coumarins. For some embodiments, the alignment layer may include polyimide, and the alignment layer may be rubbed with a velvet cloth or cotton cloth in order to at least partially order at least a portion of the surface of the alignment layer.

[0105] Further, the alignment layer may include at least partially ordered polymer sheets. For example, a polyvinyl alcohol sheet can be at least partially ordered by stretching (e.g., uniaxially stretching) the sheet, and the stretched sheet can then be bonded to at least a portion of the surface of the optical substrate to form an alignment facility. Alternatively, an ordered polymer sheet can be prepared by a method that at least partially orders the polymer chains during manufacture, such as by extrusion. Further, an at least partially ordered polymer sheet can be formed by: casting or otherwise forming a liquid crystal material sheet, and then at least partially ordering the sheet, for example, by exposing the sheet to a magnetic field, an electric field, and / or a shear force. Still further, an at least partially ordered polymer sheet can be prepared using a photo-alignment method. For example, a sheet of photo-aligning material can be formed, for example, by casting, and then at least partially ordered by exposure to linearly polarized ultraviolet radiation.

[0106] The alignment layer may include at least a partially treated surface. As used herein, the term "treated surface" refers to at least a portion of a surface that has been physically altered to create at least one ordered region on at least a portion of the surface. Examples of treated surfaces include, but are not limited to, rubbed surfaces, etched surfaces, and embossed surfaces. Further, the treated surface may be patterned, for example, using photolithography or interferometric imaging techniques. For some embodiments, the surface of the alignment layer may be a treated surface selected from, for example, a chemically etched surface, a plasma etched surface, a nano-etched surface (such as a surface etched using a scanning tunneling microscope or an atomic force microscope), a laser etched surface, and / or an electron beam etched surface.

[0107] When the alignment layer includes a treated surface, the treated surface may be formed by depositing a metal salt (such as a metal oxide or a metal fluoride) onto at least a portion of a surface (e.g., the surface of the alignment layer itself, or the surface of a primer layer), and then etching the deposit to form the treated surface. Methods for depositing metal salts that are well known in the art include, but are not limited to, plasma vapor deposition, chemical vapor deposition, and sputtering. The etching may be carried out according to methods well known in the art, such as those previously described herein.

[0108] As used herein, the term "Langmuir - Blodgett film" means one or more at least partially ordered molecular films on a surface. A Langmuir - Blodgett film may be formed, for example, by dipping a substrate into a liquid one or more times such that it is at least partially covered by the molecular film, and then removing the substrate from the liquid such that, due to the relative surface tensions of the liquid and the substrate, the molecules of the molecular film are at least partially ordered along substantially one (or a single) general direction. As used herein, the term molecular film refers to a monolayer (i.e., a single layer) as well as a film comprising more than one monolayer.

[0109] Any of the coated articles of the present invention described above may further include an alignment transfer material between the alignment layer and the layer formed from a photopolymerizable coating composition. The alignment transfer material may be aligned by interacting with the alignment layer, and correspondingly, the photopolymerizable anisotropic material and (if present) the photochromic - dichroic compound and / or the dichroic compound may be aligned by interacting with the alignment transfer material. The alignment transfer material may facilitate the propagation or transfer of a suitable alignment or orientation from the alignment layer to the photochromic - dichroic compounds of the photochromic - dichroic layer.

[0110] Examples of alignment transfer materials include, but are not limited to, those liquid crystal materials described above. It is possible to align the molecules of the liquid crystal material with an aligned surface. For example, the liquid crystal material can be applied to a surface that has been aligned and then aligned such that the long axes of the liquid crystal molecules adopt an orientation that is generally parallel to the general direction of the orientation of the surface. The liquid crystal material of the alignment transfer material can be at least partially ordered by alignment with an alignment layer such that the long axes of the molecules of the liquid crystal material are generally parallel to, for example, a first general direction of an alignment facility. In this way, the general direction of the alignment layer can be transferred to the liquid crystal material, which in turn can transfer the general direction to another structure or material. Further, if the alignment layer includes a plurality of regions having general directions that together form a design or pattern, the design or pattern can be transferred to the liquid crystal material by aligning the liquid crystal material with the respective regions of the alignment layer. Additionally, although not required, at least a portion of the liquid crystal material of the alignment transfer material can be exposed to at least one of a magnetic field, an electric field, linearly polarized infrared radiation, linearly polarized ultraviolet radiation, and linearly polarized visible radiation while at least partially aligning with at least a portion of the alignment layer.

[0111] Once the anisotropic material present in the photopolymerizable coating composition has been ordered, the ordered photopolymerizable coating composition is exposed to a light emitting diode light source having a peak emission wavelength in the range from 385 to 460 nanometers, such as from 390 to 460 nanometers or from 410 to 460 nanometers, to effect curing (i.e., polymerization) of the photopolymerizable coating composition. For a photopolymerizable coating composition containing a photochromic-dichroic dye, the peak emission wavelength of the light emitting diode light source is preferably selected to have a minimum overlap with the absorbance of the unactivated state of the photochromic dye while still overlapping with the absorbance of the selected one or more photoinitiators. The minimal overlap of the emission with the dye absorbance helps to ensure good cure-through and limits the likelihood of light degrading the dye during coating curing. For a photopolymerizable coating composition containing a photochromic dye, longer wavelength or lower energy peak emission wavelengths are generally used provided that they still sufficiently overlap with the absorbance of the selected one or more photoinitiators. It has been found that light of longer wavelengths generally results in less degradation of the dye and other coating materials.

[0112] The light-emitting diode light source can be an organic light-emitting diode; and / or an inorganic light-emitting diode, such as those prepared using alloys of some or all of aluminum nitride, gallium nitride, and indium nitride. Commercially available light sources incorporating suitable inorganic light-emitting diodes include the LB80-438P1-84 or JL3-395-G2-12 units from Clearstone Technologies. Commercially available light sources incorporating suitable inorganic light-emitting diodes can also be obtained from Heraeus Noblelight America LLC or Phoseon Technology.

[0113] As will be understood by those skilled in the art, the exposure time (i.e., irradiation time) required to effect curing of the photopolymerizable coating composition will vary depending on the nature and amount of the components present in the photopolymerizable coating composition, the thickness of the applied coating, and the specific wavelength and intensity of the light-emitting diode light source.

[0114] As previously mentioned, the photoinitiator present in the photopolymerizable coating composition should be capable of being activated at the peak emission wavelength of the light-emitting diode light source to ensure sufficient polymerization of the coating composition components. In addition, since the unactivated state of the photochromic compound absorbs certain wavelengths of actinic radiation, the absorption wavelengths of any photochromic compound and / or one or more of the photochromic-dichroic compounds that can be included in the photopolymerizable coating composition generally have no or only little overlap with the peak emission wavelength of the light-emitting diode light source.

[0115] For example, when the photopolymerizable coating composition further comprises a photochromic compound and / or a photochromic-dichroic compound, the light-emitting diode light source can have a peak emission wavelength ranging from 410 to 460 nanometers to minimize the overlap between the emission wavelength of the light-emitting diode light source and the absorbance of the unactivated state of the photochromic compound and / or the photochromic-dichroic compound.

[0116] In addition to one or more layers of the photopolymerizable coating composition and any alignment layer applied to the substrate prior to applying the one or more layers of the photopolymerizable coating composition, the coated article prepared by the method of the present invention may optionally include one or more additional layers. Examples of such additional layers may include, but are not limited to, primer coatings and films (typically applied to one or more substrate surfaces prior to depositing the photopolymerizable coating composition); protective coatings and films (applied before or after the photopolymerizable coating composition is deposited on the substrate surface, including transition coatings and films, as well as abrasion-resistant coatings and films); anti-reflection coatings and films; photochromic coatings and films, polarizing coatings and films; and combinations thereof. As used herein, the term "protective coating or film" refers to a coating or film that can prevent wear or abrasion, provide a transition in properties from one coating or film to another, prevent the effects of polymerization chemicals, and / or prevent degradation due to environmental conditions such as moisture, heat, ultraviolet light, oxygen, etc.

[0117] As used herein, the term "transition coating and film" means a coating or film that helps to produce a gradual change in properties or compatibility between two coatings or films, or between a coating and a film. For example, although not limited herein, a transition coating can help to produce a gradual change in hardness between a relatively hard coating and a relatively soft coating. Non-limiting examples of transition coatings include radiation-cured acrylate-based thin films, as described in U.S. Patent No. 7,452,611B2, which is hereby specifically incorporated herein by reference.

[0118] As used herein, the term "abrasion-resistant coating and film" refers to a protective polymeric material that exhibits higher abrasion resistance than a standard reference material, e.g., a polymer made from monomers available from PPG Industries, Inc., tested in a method comparable to ASTM F-735 (Standard Test Method for Abrasion Resistance of Transparent Plastics and Coatings Using the Oscillating Sand Method). Non-limiting examples of abrasion-resistant coatings may include, but are not limited to, abrasion-resistant coatings containing silanes, siloxanes, abrasion-resistant coatings based on inorganic materials such as silica, titanium dioxide, and / or zirconia, organically based abrasion-resistant coatings of the ultraviolet-curable type, oxygen barrier coatings, UV shielding coatings, and combinations thereof. Non-limiting examples of commercial hard coating products include and Coatings, which are available from SDC Coatings, Inc. and PPG Industries, Inc., respectively.

[0119] In some aspects, the wear-resistant coating or film (commonly referred to as a hard coating) can be selected from hard coating materials recognized in the art, such as organosilane wear-resistant coatings. Organosilane wear-resistant coatings (commonly referred to as hard coatings or silicone-based hard coatings) are well known in the art and are commercially available from various manufacturers, such as SDC Coatings, Inc. and PPG Industries, Inc. See U.S. Patent No. 4,756,973, column 5, lines 1-45; and U.S. Patent No. 5,462,806, column 1, line 58 through column 2, line 8 and column 3, line 52 through column 5, line 50. The disclosures of these patents describe organosilane hard coatings and the disclosures of these patents are incorporated herein by reference. Regarding the disclosure of organosilane hard coatings, reference is also made to U.S. Patent Nos. 4,731,264, 5,134,191, 5,231,156 and International Patent Publication No. WO 94 / 20581, and the disclosures of these patents are also incorporated herein by reference. The hard coating can be applied by coating methods recognized in the art, such as, but not limited to, roll coating, spray coating, curtain coating, and spin coating.

[0120] Non-limiting examples of suitable anti-reflection coatings and films include single layers, multi-layers, or films of metal oxides, metal fluorides, or other such materials, which can be deposited onto the articles disclosed herein (or onto films applied to the articles), for example, by vacuum deposition, sputtering, etc. Non-limiting examples of suitable conventional photochromic coatings and films include, but are not limited to, coatings and films containing conventional photochromic materials.

[0121] The method of the present invention can be used to prepare any of a variety of coated articles, such as any optical element selected from the group consisting of: ophthalmic articles, display articles, windows, and mirrors. The preparation of liquid crystal cells is also contemplated. The method is particularly suitable for preparing ophthalmic articles selected from: corrective lenses, non-corrective lenses, contact lenses, and protective lenses. The preparation of goggles, face masks, intraocular lenses, and magnifying glasses is also contemplated.

[0122] For example, the present invention relates to (e.g., but not limited to) the following aspects.

[0123] In a first aspect, the present invention may relate to a method for preparing a coated article, the method comprising: (a) providing a substrate; (b) applying a photopolymerizable coating composition to at least a portion of the substrate, the photopolymerizable coating composition comprising: (1) a photopolymerizable anisotropic material, and (2) a photoinitiator; (c) ordering the anisotropic material present in the photopolymerizable coating composition; and (d) exposing the ordered photopolymerizable coating composition of (c) to a light-emitting diode light source having a peak emission wavelength ranging from 385 to 460 nanometers to cure the photopolymerizable coating composition, wherein the photoinitiator is capable of being activated at the peak emission wavelength of the light-emitting diode light source.

[0124] In a second aspect of the present invention, in the method of the first aspect of the present invention, the photopolymerizable coating composition further comprises a material selected from the group consisting of: a photochromic compound, a dichroic compound, a photochromic-dichroic compound, and mixtures thereof.

[0125] In a third aspect of the present invention, in the method as described above for the first or second aspect, the photopolymerizable coating composition further comprises a photochromic compound and / or a photochromic-dichroic compound, and the light source has a peak emission wavelength ranging from 410 to 460 nanometers.

[0126] In a fourth aspect of the present invention, in the method according to any one of the preceding first to third aspects, the substrate of (a) comprises a polymeric material selected from the group consisting of: polycarbonate, polycyclic olefin, polyurethane, poly(urea)urethane, polythiourethane, polythi(urea)urethane, poly(allyl carbonate) polymer, cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate poly(vinylidene chloride), poly(ethylene terephthalate), polyester, polysulfone, polyolefin, copolymers thereof, and mixtures thereof.

[0127] In a fifth aspect of the present invention, in the method according to any one of the preceding first to fourth aspects, the photopolymerizable coating composition is applied by an application method selected from the group consisting of: spin coating, spraying, ultrasonic spraying, curtain coating, dip coating, roll coating, flow coating, wire coating, overcoating, and combinations thereof.

[0128] In a sixth aspect of the present invention, in the method according to any one of the preceding first to fifth aspects, the photopolymerizable anisotropic material present in the photopolymerizable coating composition comprises a photopolymerizable liquid crystal monomer.

[0129] In a seventh aspect of the present invention, in the method according to any one of the foregoing first to sixth aspects, the photopolymerizable anisotropic material present in the photopolymerizable coating composition is at least partially ordered by exposure to a magnetic field, an electric field, linearly polarized infrared radiation, linearly polarized ultraviolet radiation, linearly polarized visible radiation, a shear force, or a combination thereof.

[0130] In an eighth aspect of the present invention, in the method according to any one of the foregoing first to seventh aspects, the photoinitiator is selected from the group consisting of: phosphine-based photoinitiators, benzoyl-based photoinitiators, substituted benzoyl-based photoinitiators, and mixtures thereof.

[0131] In a ninth aspect of the present invention, in the method according to any one of the foregoing first to eighth aspects, before applying the photopolymerizable coating composition, the substrate of (a) comprises one or more coatings thereon.

[0132] In a tenth aspect of the present invention, in the method according to the foregoing ninth aspect, before applying the photopolymerizable coating composition, the substrate (a) comprises at least an alignment facility layer thereon.

[0133] In an eleventh aspect of the present invention, in the method according to any one of the foregoing first to tenth aspects, the coated article is an optical element selected from the group consisting of: ophthalmic articles, display articles, windows, and mirrors.

[0134] In a twelfth aspect of the present invention, in the method according to the foregoing eleventh aspect, the coated article is an ophthalmic article selected from: corrective lenses, non-corrective lenses, contact lenses, and protective lenses.

[0135] In a thirteenth aspect of the present invention, in the method according to any one of the foregoing first to twelfth aspects, the light-emitting diode light source is an organic light-emitting diode.

[0136] In a fourteenth aspect of the present invention, in the method according to any one of the foregoing first to twelfth aspects, the light-emitting diode light source is an inorganic light-emitting diode.

[0137] The present invention is described in the following illustrative and non-limiting examples. Many possible modifications and variations will be apparent to those skilled in the art.

[0138] Examples

[0139] Part 1: Preparation of Photopolymerizable Coating Compositions Containing Photopolymerizable Anisotropic Materials and Photoinitiators

[0140] Coatings A to E

[0141] Five photopolymerizable coating compositions (Coatings A - E) containing a photopolymerizable anisotropic material and a photoinitiator were prepared using the materials listed in Table 1 below and as described below. The amounts listed are in parts by weight.

[0142] For each coating, the materials of Charge 1 were combined in an amber wide - mouth bottle equipped with a magnetic stir bar and stirred at room temperature for at least two hours until the composition appeared homogeneous. Next, for Coatings A, B, and C, the materials for Charge 2 as indicated in Table 1 were added and the combined materials were stirred on a hot plate set at 90 °C for one hour. For Coatings D and E, the Charge 2 addition or heating step was not performed. Next, Charge 3 was added and then the combined materials were stirred on a hot plate set at 90 °C for one hour. Charge 4 was added and the combined materials were stirred on a hot plate set at 65 °C for thirty minutes. After cooling, Charge 5 was added and the mixture was stirred at room temperature for about thirty minutes. Then each of the resulting coating mixtures was passed through a polyvinylidene fluoride filter with a 5.0 - micron pore size before use.

[0143] Table 1

[0144] Composition of Coatings A - E (parts by weight)

[0145]

[0146] 1 Arylkyl - modified polymethylalkylsiloxane, available from BYK Chemie, USA.

[0147] 2 A mixture of three photochromic - dichroic indeno - fused naphthopyran dyes formulated to appear gray upon activation (hereinafter referred to as "PC dye blend").

[0148] 3 Blue fixed - shade dichroic dye.

[0149] 4 Liquid crystal monomer 4 - (3 - acryloyloxypropoxy) - benzoic acid 2 - methyl - 1,4 - phenylene ester, commercially available from EMD Chemicals, Inc.

[0150] 54-((4-((8-((6-((6-((6-((6-((6-((6-((6-(Methacryloyloxy)hexanoyl)oxy)hexanoyl)oxy)hexanoyl)oxy)hexanoyl)oxy)hexanoyl)oxy)hexanoyl)oxy)hexanoyl)oxy)octyl)oxy)benzoyl)oxy)phenyl 4'-pentyl-[1,1'-bi(cyclohexane)]-4-carboxylate, which is prepared according to the procedure described in U.S. Patent No. 7,910,019 B2.

[0151] 6 1-(6-(6-(6-(6-(6-(6-(6-(6-(8-(4-(4-(4-(6-Acryloyloxyhexyloxy)benzoyloxy)phenoxycarbonyl)phenoxy)octyloxy)-6-oxohexyloxy)-6-oxohexyloxy)-6-oxohexyloxy)-6-oxohexyloxy)-6-oxohexyloxy)-6-oxohexyloxy)-6-oxohexyloxy)-6-oxohexanol, which is prepared according to Example 17 in U.S. Patent No. 7,910,019 B2.

[0152] 7 3-Methyl-4-((4-pentylcyclohexane-1-carbonyl)oxy)phenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate.

[0153] Part 2: Measurement of the Absorbance Spectra of the Photoinitiator and PC Dye Blends

[0154] The absorbance spectra of the PC dye blend, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide photoinitiator, and 2-hydroxy-2-methylpropiophenone photoinitiator were characterized to help interpret the results of some of the following examples. A 10.6% wt. solution of the PC dye blend in anisole was prepared and then diluted two thousand-fold, and subsequently the absorbance was measured in a quartz cell with a one-centimeter path length. The measured absorbance spectrum is depicted in Figure 1 Spectrum 1.

[0155] A 1.32% wt. solution of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide in anisole was prepared and then diluted fifty-fold, and subsequently the absorbance was measured in a quartz cell with a one-centimeter path length. The measured absorbance spectrum is depicted in Figure 2 Spectrum 2. Similarly, a 1.04% wt. solution of 2-hydroxy-2-methylpropiophenone in anisole was prepared and then diluted fifty-fold, and subsequently the absorbance was measured in a quartz cell with a one-centimeter path length. The measured absorbance is depicted in Figure 2 Spectrum 3.

[0156] Absorbance measurements were performed using a Cary Series UV-Visible spectrophotometer from Agilent Technologies, Inc. The instrument was set with the following parameters: scan speed = 600 nm / min; data interval = 1.0 nm; integration time = 100 ms; SBW (slit bandwidth) = 2.0. A 1-cm quartz cuvette filled with anisole was used for baseline correction and to zero the instrument. The test solutions were tested at ambient room temperature (23 ± 3 °C). Before measurement, the solutions containing the PC dye blend were stored in amber vials to avoid activation of the dye.

[0157] Part 3: Preparation of Coated Test Samples

[0158] Made from Finished plano lenses prepared from monomers (6 bases, 65 mm diameter) were used as substrates for all coated articles. The lenses were cleaned by wiping with a paper cloth dipped in acetone and then air-dried. Next, each lens was corona-treated with a Power Generator HV 2000 from Tantec EST (serial number 020270), with the Power Generator HV 2000 set to 70 kV and 1000 W and a belt speed of 3 ft / min.

[0159] After corona treatment, a photoalignment coating prepared as described in U.S. Patent No. 9,475,901 in Example 1 was applied to each lens via a spin-coating process, the synthesis of which is incorporated herein by reference. Approximately 1.5 mL of the photoalignment coating was applied to a portion of the lens surface. The lens was rotated for two seconds at 800 revolutions per minute (rpm) using a spin processor (WS-650MZ-23NPPB) from Laurell Technologies Corporation, then rotated at 1,000 rpm for seven seconds, and then rotated at 2,500 rpm for four seconds. Next, each coated lens was placed in a forced-air convection oven set at 80 °C for approximately thirteen minutes.

[0160] Cool the lenses, and then expose each lens to linearly polarized ultraviolet light. The light source was positioned such that the light was polarized in a plane perpendicular to the top surface of the lens. Use a UV PowerPuck TM II high-energy radiometer (S / N: 18938) to measure the energy density to which each photoalignment coating was exposed. The measured energy density was in the following ranges: UV-V was 4.6 to 5.0 J / cm 2 , UV-A was 3.7 to 4.1 J / cm 2 , UV-B was 0.12 to 0.14 J / cm2 and the UV-C is from 0.12 to 0.19 J / cm 2 .

[0161] Next, each of the photopolymerizable coatings (coatings A to E) was applied to the lens via a spin coating process. The coating compositions for each example and comparative example are indicated in Tables 2 to 4 below. In each case, approximately 1.5 mL of the coating was applied to a portion of the lens surface. The lens was rotated at 400 rpm for 6 seconds and then at 900 rpm for 4 seconds using a spin processor (WS-650MZ-23NPPB) from Laurell Technologies Corporation. Then each coated lens was placed in a forced air convection oven set at 65 °C for thirty minutes.

[0162] For Examples 1, 2, 5, 6, 8, and 9 and Comparative Examples 11 and 12, each coated lens was then placed in a nitrogen-purged chamber with a borosilicate glass window. The light-emitting diode light source was located directly above the window at an incident angle perpendicular to the lens surface and at a distance of approximately 7 centimeters (cm). After cooling each lens in the nitrogen-purged chamber for three minutes, the light-emitting diode light source was turned on to irradiate the coated lens surface. As indicated in Tables 2 to 4 below, a light-emitting diode light source with a peak emission wavelength of 395 nm or 438 nm was used. The energy density emitted by each light source was measured using a UV Power Puck TM II high-energy radiometer (S / N: 18938). During a 90-second exposure period, the lenses irradiated with the light-emitting diode light source having a peak emission wavelength of 395 nm were exposed to the following energy densities: UV-V was from 55.9 to 62.9 J / cm 2 and the UV-A was from 1.8 to 2.3 J / cm 2 . During a 60-second exposure period, the lenses cured using the light-emitting diode light source having a peak emission wavelength of 438 nm were exposed to the following energy densities: UV-V was from 15.0 to 15.4 J / cm 2 .

[0163] For Comparative Examples 3, 4, 7, 10, and 13, the coated lenses were cooled for three minutes. Then, using a conveyor system, the lenses were passed through a nitrogen-purged chamber equipped with a series of D-type bulbs located above the glass windows at the top of the chamber. The glass windows had a high transmittance for ultraviolet and visible light. Each coating was exposed to the energy density measured using a UV Power Puck TM II high-energy radiometer (S / N: 18938) as follows: UV-V was 16.3 J / cm 2, the UV-A is 17.1 J / cm 2 , the UV-B is 4.0 J / cm 2 , and the UV-C is 0.7 J / cm 2 .

[0164] Finally, place all the lenses in a forced air convection oven set at 105 °C for three hours.

[0165] Part 4: Characteristics of Coated Test Samples

[0166] First, visually inspect each coated lens for the curing of the photopolymerizable layer. It was observed that the coatings of Comparative Example 4 had an uneven wavy top surface and cracks in the coating. The coatings of Comparative Examples 11 and 12 were not cured. These coatings remained liquid and were easily wiped off. The other coatings seemed to be cured upon visual inspection.

[0167] Except for Comparative Examples 4, 11, and 12, the microhardness of the photopolymerizable coatings was tested using an HM2000S nanoindentation system obtained from Fisher Technology. The hardness was measured at a depth of 2 microns for 15 seconds using a 100 mN load cell. Each coating was measured three times. Tables 2 to 4 below report the average results for photochromic-dichroic lenses, fixed-tone dichroic lenses, and dye-free lenses, respectively.

[0168] The photochromic performance characteristics of the coated lenses of Examples 1 and 2 and Comparative Example 3 were tested according to the following procedure. Before the response test on the optical bench, the specimens were conditioned in a multi-step custom conditioning unit. First, it was exposed to 365 nm ultraviolet light at a distance of about 10 cm from the electromagnetic radiation source for 10 minutes to pre-activate the photochromic compound. The UVA irradiance at the sample was measured to be 7.7 W / m². Next, the specimen was heated to and maintained at a temperature of 70 °F (21.1 °C) for 10 minutes. Finally, the heating element was turned off, and the F17T8 yellow halogen lamp was turned on for 30 minutes to fade or deactivate the photochromic compound in the specimen. The illuminance from the yellow halogen lamp at the specimen was measured to be 9.0 Klux. Then the specimen was kept in a dark environment for 1 hour before testing in order to cool and continue to fade back to the ground state.

[0169] The optical properties of the specimens were measured using an optical bench and the absorption ratio and photochromic characteristics were obtained. Each specimen was placed on an optical bench with an activation light source positioned at an incident angle of 35 ± 1° to the surface of the test sample. The activation light source used was a xenon arc lamp powered by a Newport / Oriel 69911 type 300 W power supply, which was equipped with VS-25 high-speed computer-controlled shutter, which is temporarily closed during data collection so that stray light does not interfere with the data collection process; removing short-wavelength radiation A 3mm KG-2 heat-absorbing filter; one or more neutral density filters for intensity attenuation and condenser lenses for beam collimation. The arc lamp is equipped with a digital exposure controller and a sensor (Newport / Oriel model 68945) to maintain fine control of the output over time.

[0170] The broadband light source for monitoring response measurements is positioned perpendicular to the surface of each specimen. By collecting and combining separately filtered light from a 100-watt tungsten-halogen lamp (controlled by a ZUP60-14 constant voltage power supply) using a split-tip, bifurcated fiber optic cable, an increased signal at shorter visible wavelengths is obtained. The light from one side of the tungsten-halogen lamp is filtered with a KG1 filter to absorb heat and filtered with a B-440 filter to allow shorter wavelengths to pass through. The other side of the light is filtered or unfiltered with a KG1 filter. The light is collected by focusing the light from each side of the lamp onto separate ends of the split-tip, bifurcated fiber optic cable and then combining it into a single light source that emerges from a single end of the cable. A 4- to 6-inch (10.2 cm to 15.25 cm) light pipe is attached to the single end of the cable to ensure proper mixing. The broadband light source is equipped with a VS-25 high-speed computer-controlled shutter that is temporarily opened during data collection.

[0171] The polarization of the light source is achieved by passing the light from the single end of the cable through a Moxtek polarizer (analyzer polarizer) held on a computer-driven, motorized rotating stage, polarizer (model M-061.PD, M660, U651 or equivalent from Physik Instrumente). The monitoring beam is set such that one polarization plane (0°) is perpendicular to the plane of the optical table and the second polarization plane (90°) is parallel to the plane of the optical table. The specimens are run in air at 23 °C ± 0.1 °C (this temperature is maintained by a temperature-controlled air chamber).

[0172] To align the specimens, a second polarizer was added to the optical path (a research-grade film polarizer such as the polarizer SPF-50C-32 from OptoSigma). The second polarizer was set at 90° (+ / - 0.1°) to the first analyzer polarizer. Each test sample was placed in an air cell in a self-centering holder mounted on a rotating stage (type M-061.PD, M660, U651, or equivalent from Physik Instrumente). The laser beam (Coherent - ULN 635 diode laser) was directed through the crossed polarizers and the sample. The signal intensity of the laser beam was measured in relative counts by a spectrophotometer. The specimen was rotated 120° in 3° increments to locate the minimum transmitted light intensity of the laser beam. The specimen was then positioned near the minimum transmitted light intensity and then rotated in 0.1° steps through 12° to locate the minimum transmission to + / - 0.1° depending on the sample quality. The specimen was then finally positioned at the minimum transmission angle. At this point, the specimen was aligned parallel or perpendicular to the Moxtek analyzer polarizer. The second polarizer and the diode laser beam were removed from the optical path. Using this procedure, the specimens were aligned to + / - 0.1° before any activation.

[0173] For measurements, each specimen was exposed to UVA from an activation light source at approximately 6.7 W / m 2 for 15 minutes to activate the photochromic compound. Exposure was verified at the start of each day using an International Light Research spectroradiometer (model ILT950 or ILT950FC). Then light from a monitoring source polarized to the 0° polarization plane was passed through the sample and focused onto a 1-inch (2.54 cm) integrating sphere which was connected to an OCEAN S2000 (or similar) spectrophotometer using a single-function fiber optic cable. After passing through the sample, spectral information was collected using OCEAN OPTICS Drivers in combination with proprietary software from Transitions Optical Limited. When the photochromic material was activated, the position of the analyzer polarizer was rotated back and forth to polarize the light from the monitoring light source to the 90° polarization plane and back. Data was collected at 5-second intervals for approximately 900 seconds during activation. For each test, the rotation of the polarizer was adjusted to collect data in the following polarization plane sequence: 0°, 90°, 90°, 0°, etc.

[0174] Using the CIE system with a D65 illuminant and a 10° observer (Colorimetry, 4th Edition, CIE 015:2018), the CIE Y, a*, and b* values for the faded states reported in Table 2 were calculated from the measured initial transmittance of the lens in the faded state (unactivated state). The CIE b* value is a measure of the degree of yellowness presented by the lens. A higher CIE b* value indicates a yellower appearance.

[0175] The polarization efficiency (“PE”) values reported in Table 2 were calculated based on the change in optical density (ΔOD) from the faded state (i.e., unactivated state) to the darkened state (i.e., activated state) to eliminate any contribution of the unactivated lens (such as reflection or absorbance in the unactivated state) to the two polarization states. The change in optical density was determined by: establishing the initial transmittance, then opening the shutter from the xenon lamp to provide ultraviolet radiation to change the specimen from the faded state to the activated state. Data were collected at selected time intervals, the transmittance in the activated state was measured, and the change in optical density was calculated according to the formula: ΔOD = log(%Tb / %Ta), where %Tb is the percentage transmittance in the faded state, %Ta is the percentage transmittance in the activated state, and the logarithm is base 10. From the ΔOD values measured at 90° polarization (perpendicular orientation to the analyzer polarizer, minimum transmittance) and 0° polarization (parallel orientation to the analyzer polarizer, maximum transmittance), CIE Y values were determined at 90° polarization and 0° polarization for the D65 illuminant and 10° observer. These values (Y 90 and Y0) were used to calculate the polarization efficiency according to the formula: PE = 100*(abs(Y0 - Y 90 )) / (Y0 + Y 90 )) (note that the PE value is relative to the research-grade analyzer polarizer, not between two similar sample polarizers). The PE ranges from 0 to 100, and a higher value indicates better polarization efficiency.

[0176] Measure the optical properties of Example 5 and Example 6 and Comparative Example 7 using the following procedure. Use a CARY 4000 or 6000i UV-Visible spectrophotometer equipped with a self-centering sample holder. Measure the samples using Cary WinUV4.2 software with a customized ADL function. Place a UV polarizer (“analyzer polarizer”, UVD260A, available from Moxtek) in front of the light source. The instrument is set with the following parameters: scan speed = 600 nm / min; data interval = 1.0 nm; integration time = 100 ms; absorbance range = 0 - 6.5; y-mode = absorbance; x-mode = nanometers; and the scan range is from 370 nm to 800 nm. Set the options for 3.5 SBW (slit bandwidth) and double beam mode. Set the baseline option for zero / baseline correction. Use a 2.5 OD neutral density filter (screen or reflective ND) (referred to as the post-beam attenuation filter) in the reference path for all scans. Test the coated substrate samples in air at ambient room temperature (23 ± 3 °C). Collect the baseline after placing the analyzer polarizer and the post-beam attenuation filter.

[0177] Use a rotary stage (PI M-060.PD rotary stage with an M-863 controller) to determine the perpendicular and parallel orientations of each sample polarizer relative to the analyzer polarizer to control the angle between the polarizers by using proprietary software that connects the Cary UV-VIS spectrophotometer to the motorized rotary stage. While the angle of the sample is rotated, monitor the absorbance of the light passing through the polarizer at the peak absorbance wavelength. The maximum absorbance point is determined to be within ±0.1° of the cross-polarization state between the analyzer polarizer and the sample. At this time, the sample polarizer is perpendicular to the Moxtek analyzer polarizer. Obtain the parallel position by rotating the stage 90° clockwise or counterclockwise.

[0178] For each sample, collect absorbance spectra at parallel and cross-polarization positions relative to the analyzer polarizer. Process the data analysis using the Igor Pro software package available from WaveMetrics and proprietary code developed within Igor Pro. Load the spectra into the Igor Pro software package and calculate the Y, a*, and b* values under the CIE system (colorimetry, 4th edition, CIE 015:2018) with a D65 illuminant and a 10° observer using the absorbance data. Calculate the polarization efficiency at the peak absorbance wavelength of 675 nm using the following formula:

[0179] PE = 100*(abs(T0 - T 90 ) / (T0 + T 90 ))

[0180] where T0 and T 90Transmission values at the absorbance peak at 675 nm when the sample and the analyzer polarizers are parallel and perpendicular, respectively. PE ranges from 0 to 100, and the higher the value, the better the polarization efficiency. The results are given in Table 3 below.

[0181] Using an Ultrascan PRO instrument from HunterLab, Y, a*, and b* values were measured for Example 8 and Example 9, as well as Comparative Example 10 and Comparative Example 13, under the CIE system (Colorimetry, 4th Edition, CIE 015:2018) with a D65 illuminant and a 10° observer. The results are reported in Table 4 below.

[0182] Table 2

[0183]

[0184] 8 A light-emitting diode light source from Clearstone Technologies with a peak emission wavelength of 438 nm. Two LB80-438P1-84 units were used with a CF3000 controller.

[0185] 9 A light-emitting diode light source from Clearstone Technologies with a peak emission wavelength of 395 nm. One JL3-395-G2-12 unit was used with a CF3000 controller.

[0186] 10 The coating properties could not be measured. The coating had an uneven wavy top surface and cracks.

[0187] For the photochromic-dichroic lenses of Example 1 and Example 2 and Comparative Example 3, the data in Table 2 show that coatings irradiated with a selected light-emitting diode light source having a peak emission wavelength in the range of 385 - 460 nm (Example 1 and Example 2) instead of a conventional broadband D-type bulb light source (Comparative Example 3) produce photochromic-dichroic lenses with higher fade-state clarity (higher fade Y), less fade-state yellowness (lower fade b*), and better activation-state polarization efficiency (higher PE). Under the curing conditions used, the coatings of Example 1 and Example 2 and Comparative Example 3 were all cured to an acceptable hardness of ≥43 N / mm 2 Among the light-emitting diode light sources, the one with the longer peak emission wavelength of 438 nm performed best, resulting in the lowest fade-state b* and the highest activation-state polarization efficiency.

[0188] Although not intending to be bound by any theory, light-emitting diodes with peak emission wavelengths in the range of 385 nm to 460 nm for curing the coated substrates of Examples 1 and 2 are believed to produce coatings with higher performance, in part because they limit the degradation of photochromic-dichroic dyes and other coating materials by selectively emitting in the lower energy wavelength range. Broadband D-type bulb light sources emit over a wide energy range that includes higher energy short-wavelength ultraviolet light, which can more readily degrade dyes and other coating materials, resulting in yellowing and loss of PE. Although not intending to be bound by any theory, light-emitting diodes in the range of 410 to 460 nm with a peak wavelength of 438 nm are believed to produce the best results because the wavelength range of the light emitted by this light-emitting diode extends beyond the baseline where the absorbance of the PC dye blend in the unactivated state approaches 420 nm (see Figure 1 , Spectrum 1), but its emission still overlaps with the absorbance of the selected phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide photoinitiator (see Figure 2 , Spectrum 2). Therefore, the light from this source has a minimal effect on the dye. In addition, since the light is not absorbed or shielded by the dye, this light can effectively activate the photoinitiator.

[0189] Comparative Example 4 exhibited poor through-curing for the photochromic-dichroic coating. As seen above, only the top of the coating was cured, resulting in an uneven wavy top surface and a cracked coating. Comparative Example 4 used Coating B, which contains 2-hydroxy-2-methylpropiophenone photoinitiator instead of the phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide photoinitiator used in Coating A. The absorbance of 2-hydroxy-2-methylpropiophenone (see Figure 2 , Spectrum 3) is in the region where the PC dye blend strongly absorbs. The strong absorbance of the PC dye blend in this region shields the emission from the D-type bulb, thus limiting the activation of the 2-hydroxy-benzophenone photoinitiator near the bottom of the coating. In contrast, in Examples 1 and 2 using Coating A, good through-curing was achieved using a light-emitting diode light source with a peak emission wavelength in the region of 385 to 460 nm in combination with a photoinitiator that absorbs these longer wavelengths, where the absorbance of the PC dye blend is reduced or close to zero.

[0190] Table 3

[0191]

[0192] 11 Measured at the peak absorbance of 675 nm.

[0193] For the fixed-tint dichroic lenses prepared as described herein, the results presented in Table 3 above show that both the selected light-emitting diode light sources (Examples 5 and 6) and the conventional broadband D-type bulb light source (Comparative Example 7) can produce fixed-tint lenses with high PE and an acceptable hardness of ≥34 N / mm 2 . However, the light-emitting diode light source is preferred because of the reduced yellowing, as indicated by the more negative b* values for Examples 5 and 6 compared to Comparative Example 7. Similar to the photochromic-dichroic lens examples, the light-emitting diode with the lowest energy peak emission wavelength of 438 nm performs the best, with the least amount of yellowing. Among the light-emitting diode light sources tested, it also results in the coated samples with the highest PE.

[0194] Table 4

[0195]

[0196]

[0197] 12 Measurement could not be performed. The coating did not cure.

[0198] For the dye-free lenses prepared as described above, the results presented in Table 4 show that irradiation with the selected light-emitting diode light sources (Examples 8 and 9) instead of the conventional broadband D-type bulb light sources (Comparative Examples 10 and 13) results in non-colored lenses with higher clarity (higher Y) and reduced yellowness (lower b*). The results presented in Table 4 also show that for light-emitting diode light sources, a photoinitiator with sufficient overlap absorbance with the emission of the light-emitting diode light source must be used. Comparative Examples 11, 12, and 13 used 2-hydroxy-2-methylpropiophenone as the photoinitiator in the coating. The broadband D-type bulb light source cured the coating with 2-hydroxy-2-methylpropiophenone (Comparative Example 13). The light-emitting diode light sources with peak emission wavelengths of 395 nm and 438 nm did not cure the coating with 2-hydroxy-2-methylpropiophenone (see Comparative Examples 11 and 12) because the emission from these light sources did not sufficiently overlap the absorbance of 2-hydroxy-2-methylpropiophenone (see Figure 2 , Spectrum 3).

[0199] Although the present invention has been described with reference to the specific details of certain embodiments of the present invention, such details are not intended to be regarded as limiting the scope of the present invention unless they are included in the appended claims.

Claims

1. A method for preparing a coated article, the method comprising: (a) providing a substrate; (b) applying a photopolymerizable coating composition to at least a portion of the substrate, the photopolymerizable coating composition comprising: (1) a photopolymerizable anisotropic material, (2) a photoinitiator; and (3) a material selected from the group consisting of: a dichroic compound, a photochromic-dichroic compound, and mixtures thereof; (c) ordering the anisotropic material present in the photopolymerizable coating composition; and (d) exposing the ordered photopolymerizable coating composition of (c) to a light-emitting diode light source having a peak emission wavelength in the range from 438 to 460 nanometers to cure the photopolymerizable coating composition, wherein the photopolymerizable anisotropic material (1) present in the photopolymerizable coating composition comprises a photopolymerizable liquid crystal monomer and is present in the photopolymerizable coating composition in an amount in the range from 50 to 99.8 weight percent, based on the total weight of the solids present in the photopolymerizable coating composition, and wherein the photoinitiator (2) is capable of being activated at the peak emission wavelength of the light-emitting diode light source, the photoinitiator (2) being selected from the group consisting of phosphine-based photoinitiators and being present in the photopolymerizable coating composition in an amount in the range from 10 to 0.1 weight percent, based on the total weight of the solids present in the photopolymerizable coating composition.

2. The method according to claim 1, wherein the photopolymerizable coating composition further comprises a photochromic compound.

3. The method according to claim 2, wherein both the photochromic compound and the photochromic-dichroic compound are present in the photopolymerizable coating composition.

4. The method according to any one of claims 1 to 3, wherein the substrate of (a) comprises a polymeric material selected from the group consisting of: polycarbonate, polycyclic olefin, polyurethane, poly(urea)urethane, polythiourethane, polythio(urea)urethane, poly(allyl carbonate) polymer, cellulose acetate, diacetate cellulose, triacetate cellulose, cellulose acetate propionate, cellulose acetate poly(vinylidene chloride), poly(ethylene terephthalate), polyester, polysulfone, polyolefin, copolymers thereof, and mixtures thereof.

5. The method according to any one of claims 1 to 3, wherein the photopolymerizable coating composition is applied by an application method selected from the group consisting of: spin coating, spraying, curtain coating, dip coating, roll coating, flow coating, wire coating, overcoating, and combinations thereof.

6. The method according to any one of claims 1 to 3, wherein the photopolymerizable coating composition is applied by an application method selected from ultrasonic spraying.

7. The method according to any one of claims 1 to 3, wherein the photopolymerizable anisotropic material present in the photopolymerizable coating composition is at least partially ordered by exposure to a magnetic field, an electric field, linearly polarized infrared radiation, linearly polarized ultraviolet radiation, linearly polarized visible radiation, shear force, or a combination thereof.

8. The method according to any one of claims 1 to 3, wherein prior to applying the photocurable coating composition, the substrate of (a) comprises one or more coatings thereon.

9. The method according to claim 8, wherein prior to applying the photocurable coating composition, the substrate (a) comprises at least an alignment facility layer thereon.

10. The method according to any one of claims 1 to 3, wherein the coated article is an optical element selected from the group consisting of: ophthalmic articles, display articles, windows, and mirrors.

11. The method according to claim 8, wherein the coated article is an ophthalmic article selected from: corrective lenses, non-corrective lenses, contact lenses, and protective lenses.

12. The method according to any one of claims 1 to 3, wherein the light-emitting diode light source is an organic light-emitting diode.

13. The method according to any one of claims 1 to 3, wherein the light-emitting diode light source is an inorganic light-emitting diode.

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