Curable coating composition

Abstract

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

Description

[0001] The present invention relates to a curable coating composition, in particular a radiation curable coating composition, for the preparation of a transparent, abrasion resistant, highly scratch resistant coating, optical articles, in particular ophthalmic articles, coated therewith, and a method of manufacturing such optical articles.

[0002] It is common practice in the art to coat at least one major surface of an optical substrate with several coatings to impart additional or improved optical or mechanical properties to the finished article. These coatings are generally referred to as functional coatings.

[0003] Various coatings that can be used to impart various mechanical and / or optical properties can be impact resistant coatings, abrasion and / or scratch resistant coatings, anti-reflective and / or reflective coatings, anti-soiling and / or anti-fogging layers.

[0004] The abrasion and / or scratch resistance of optical articles is generally insufficient compared to classic non-solar or anti-reflective lenses, which is crucial for solar lenses for sunglasses with or without prescription having a reflective front face. Indeed, the presence of a scratch on the reflective front face of a solar lens is particularly perceptible to the wearer or to the observer due to the color and brightness contrast between the light reflected from the scratch and the light reflected from the unmarred surface of the coating. The wearer can experience a decrease in the visual quality, while the observer can find the scratched solar lens less aesthetically appealing. This is especially true for reflective lenses displaying a mirror effect. Mirror coatings generally have poor abrasion resistance and are therefore easily damaged.

[0005] Different approaches can be found in the literature to improve the abrasion resistance of optical articles sensitive to scratches from the environment. The abrasion and scratch resistance properties are generally achieved by applying a hard coating to the base substrate.

[0006] It has been proposed to increase the total thickness of the anti-reflective coating, as in JP 2003-195003 and JP 2003-294906, which describe a lens coated with a primer coating, a hard coating and a 7-layer anti-reflective coating comprising alternating layers of SiO2 and TiO2, the latter being deposited with ion assistance and known to be sensitive to photodegradation.

[0007] WO 2016 / 178052 discloses a UV-curable coating composition for ophthalmic lenses comprising at least one alkylene oxide silane, at least one multifunctional acrylate monomer and / or multifunctional epoxide compound, and at least one UV absorber.

[0008] WO 2016 / 108061 discloses an ophthalmic article comprising: a first coating layer and a second coating layer, the first coating layer comprising an abrasion resistant coating layer comprising a flexible material, wherein the abrasion resistant coating layer is radiation cured; the second coating layer comprising a sputter applied anti-reflective coating layer. The ophthalmic article has a Bayer value of 1.25 or between 1.25 and 2.6, and a hand steel wool value of 3 or less.

[0009] JP 2013-227485 discloses a curable resin composition containing a fine particle of silicon dioxide, a silane coupling agent containing an epoxy group, a trifunctional or higher functional polyfunctional (meth)acrylate compound, and as an essential component, a base-soluble polymerizable resin having a weight average molecular weight of 4,000 to 50,000 (N-substituted maleimide-based monomer unit and / or a simple substance based on dialkyl-2,2'-(oxydimethylene)divinyl acetate).

[0010] US 2017 / 052446 discloses a photosensitive resin composition comprising a base-soluble polymerizable resin (A), a compound having a vinyl unsaturated group (B), a photoinitiator (C), a solvent (D), and a silane compound (E) that is not an unsaturated silane including a silane compound (E-1).

[0011] JP H10-133370 discloses a color filter composition comprising a polymerizable resin having a carboxyl group or a phenolic hydroxyl group in a side chain, a photopolymerization initiator, a monomer hardened by the action of the initiator, a pigment, a solvent, and a silane coupling agent.

[0012] JP 2007-284622 describes a surface protective layer obtained from a composition comprising (A): a block copolymer containing at least a polymer chain (X) having a fluorine-containing vinyl monomer unit and a polymer chain (Y) composed of a vinyl monomer unit having at least a silyl group capable of undergoing hydrolytic condensation, and a silyl hydrolytic condensation catalyst.

[0013] Other radiation curable hard coating compositions for protecting the optical surface of ophthalmic lenses are disclosed in WO 2001 / 018128, US 8033663, WO 2002 / 000561 and US 7018463.

[0014] Even with the best existing ophthalmic lens coatings, wearers continue to experience scratches due to abrasion and exposure to harsh environments. To address these problems, there is a need for a coating with high scratch resistance equivalent to or better than existing ophthalmic lens coatings.

[0015] It is an object of the present invention to provide a transparent optical article, preferably a lens, and more preferably an ophthalmic lens for eyeglasses, comprising an organic or mineral glass substrate optionally with an interference coating, having improved abrasion and / or scratch resistance compared to known optical articles, coated with a hard coating having robust adhesion to the substrate and good resistance to heat and temperature changes. These properties should be obtained without degrading the optical and other mechanical properties of the article, such as anti-reflective or reflective properties.

[0016] Still another object of the present invention is to provide a method of manufacturing the above defined article, which can be easily integrated into the traditional manufacturing chain and which will avoid heating the substrate.

[0017] The inventors observed that formulating curable hard coating compositions based on high functional acrylic monomers gives high scratch resistance, however, the coatings are very brittle and have a tendency to crack upon curing. Therefore, there is a need for a method to modify these acrylate based coatings to be less brittle while maintaining their scratch resistance.

[0018] The inventors found that the combination of high functional acrylates with unsaturated silanes having a lower functionality (reducing crosslinking density) results in very high scratch resistant coatings adhering to the lens substrate.

[0019] The present invention thus relates to a radiation curable coating composition comprising at least one poly(meth)acrylate compound comprising at least 6 (meth)acrylate groups, at least one unsaturated silane compound, and at least one initiator, preferably a photoinitiator, the at least one poly(meth)acrylate compound comprising at least 6 (meth)acrylate groups and the at least one unsaturated silane compound representing at least 95% by weight of the polymerizable compounds present in the composition.

[0020] The terms "comprise", "comprising", "includes", "including", "has", "having", "contains", "containing", "includes", "including", "includes", "including" and "include" and any grammatical variations thereof are open-ended transitional phrases and terms. They are used to indicate the presence of the stated features, integers, steps or components or groups but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. Thus, a method that "comprises" or "comprises" one or more steps or elements possesses those one or more steps or elements, but is not limited to possessing only those one or more steps or elements.

[0021] Unless otherwise indicated, all numbers or expressions referring to amounts, ranges, reaction conditions, and the like, used herein are to be understood to refer to approximations which can vary by + / - 10% around the stated values.

[0022] When the optical article comprises one or more surface coatings, the phrase "depositing a coating or layer on the optical article" means depositing the coating or layer on the outermost coating of the optical article, i.e. the coating closest to the air.

[0023] A coating "on" a side of the lens is defined as a coating (a) located on that side, (b) not required to be in contact with that side, i.e. one or more intermediate coatings can be disposed between that side and the coating in question (although the coating is preferably in contact with that side), and (c) not required to cover that side completely.

[0024] The term "coating" is understood to mean any layer, layer stack or film that can be in contact with a substrate and / or with another coating (e.g. a sol-gel coating or a coating made of an organic resin). The coating can be deposited or formed by various methods, including wet processing, gas processing and film transfer.

[0025] The optical article prepared according to the present application is a transparent optical article, preferably an optical lens or lens blank, and more preferably an ophthalmic lens or lens blank. The optical article can be coated with a multilayer interference coating according to the present application on its convex main face (front face), concave main face (back face / rear face) or on both faces.

[0026] In an embodiment, the optical article is coated on the back face of the lens after the back face has been surface treated in the desired geometry, typically for a prescription lens.

[0027] As used herein, the back face of a substrate in the case of a lens is intended to mean the face that is closest to the eye of the wearer when using the article. It is generally a concave face. Conversely, the front face of a substrate is the face that is farthest from the eye of the wearer when using the article. It is generally a convex face. The optical article can also be a piano article.

[0028] Herein, the term "lens" means an organic or inorganic glass lens, which comprises a lens substrate, which can be coated with one or more coating layers having different properties.

[0029] The term "ophthalmic lens" is used to mean a lens adapted to a spectacle frame, for example, to protect the eye and / or to correct vision. The lens can be chosen from afocal lenses, single vision lenses, bifocal lenses, trifocal lenses, and progressive lenses. Although ophthalmic optics is the preferred field of the application, it should be understood that the application can be applied to other types of optical articles, such as, for example, lenses for optical instruments in photography or astronomy, optical sighting lenses, eye visors, optical devices of illumination systems, etc.

[0030] In the present specification, an optical article / material is understood to be transparent when viewing an image through said optical article is not perceived with a significant loss of contrast, i.e. when an image formation through said optical article is obtained without adversely affecting the quality of the image. This definition of the term "transparent" can be applied to all objects so defined in the present specification, unless otherwise specified.

[0031] In the sense of the present application, a substrate is understood to mean a substrate without coating and generally having two main faces. The substrate can in particular be an optically transparent material having the shape of an optical article, such as an ophthalmic lens intended to be mounted on eyeglasses. In this context, the term "substrate" is understood to mean the base constitutive material of an optical lens and more particularly of an ophthalmic lens. This material acts as a support for the stack of one or more coating layers or layers.

[0032] The substrate can be made of mineral glass or organic glass, preferably organic glass. The organic glass can be a thermoplastic material (such as polycarbonates and thermoplastic polyurethanes), or a thermoset (crosslinked) material, such as diethylene glycol bis(allyl carbonate) polymers and copolymers (in particular CR-39® from PPG Industries), polyurethanes, polyepoxides, and polydialkylsiloxanes. Preferred materials for lens substrates include thermosetting polyurethanes, polythiourethanes (preferably polythiourethane resins with a refractive index of 1.60 or 1.67), polyepoxides, polycyclic sulfides (such as polycyclic sulfides with a refractive index of 1.74), and substrates based on poly(meth)acrylates and copolymers, such as substrates comprising (meth)acrylate polymers and copolymers derived from bisphenol A, polythio(meth)acrylates, and copolymers thereof and blends thereof. Preferred materials for lens substrates are polycarbonate (PC) and diethylene glycol bis(allyl carbonate) polymers, particularly substrates made of polycarbonate.

[0033] Specific examples of substrates suitable for use in this invention are those obtained from thermosetting polyurethane resins, particularly those of the MR series. and The resins are sold by Mitsui Toatsu Chemicals company. These substrates and the monomers used in their preparation are described in particular in patents US 4,689,387, US 4,775,733, US 5,059,673, US 5,087,758 and US 5,191,055.

[0034] Prior to depositing a functional coating, the surface of the article is typically subjected to physical or chemical surface activation and cleaning pretreatment to improve the adhesion of the layer to be deposited, as disclosed in WO 2013 / 013929. This pretreatment is usually performed on the surface of abrasion-resistant and / or scratch-resistant coatings (hard coatings).

[0035] This pretreatment is typically performed under vacuum. Pretreatment can be bombardment with high-energy species, such as ion beam methods (“ion pre-cleaning” or “IPC”) or electron beam methods, corona treatment, ion spallation treatment, ultraviolet treatment, or vacuum plasma treatment (typically using oxygen or argon plasma). Pretreatment can also be acid or alkali surface treatment and / or solvent surface treatment with or without ultrasonic treatment (using water or organic solvents). Many treatments can be combined. Due to these cleaning treatments, the cleanliness of the substrate surface is optimized.

[0036] High-energy matter refers to matter having an energy range of 1 to 300 eV, preferably from 10 to 150 eV, more preferably from 10 to 150 eV, and most preferably from 40 to 150 eV. High-energy matter can be chemical substances, such as ions, free radicals, or substances such as photons or electrons.

[0037] The main surface of the substrate can be coated with several functional coatings to improve its optical and / or mechanical properties. The term "coating" is understood to mean any layer, layer stack or film that can be in contact with the substrate and / or with another coating, for example a sol-gel coating or a coating made of organic resin. The coatings can be deposited or formed by various methods, including wet processes, gas treatments and film transfers. The functional coatings used herein can be chosen from, but are not limited to, these coatings: impact-resistant coatings, abrasion- and / or scratch-resistant coatings (hard coatings), interference coatings such as anti-reflective coatings, polarizing coatings, photochromic coatings, antistatic coatings, anti-fouling coatings (hydrophobic and / or oleophobic coatings), anti-fog coatings, precursors of anti-fog coatings or stacks made of two or more such coatings.

[0038] The primer coating that improves the impact resistance and / or adhesion of the additional layer in the final product is preferably a polyurethane latex or an acrylic latex. The primer coating and the abrasion- and / or scratch-resistant coating can be chosen from those described in application WO 2007 / 088312.

[0039] The interference coating can in fact be any interference coating conventionally used in the field of optical devices, in particular ophthalmic optical devices. In a non-limiting manner, the interference coating can be an anti-reflective coating, a reflective (mirror) coating, an infrared filter or an ultraviolet filter, and is preferably an anti-reflective coating.

[0040] The anti-reflective coating can be any anti-reflective coating conventionally used in the field of optical devices, in particular ophthalmic optical devices. It is also well known that anti-reflective coatings conventionally comprise a single layer or a multilayer stack of dielectric materials, typically one or more metal oxides, and / or sol-gel materials and / or organic / inorganic layers, as described in WO 2013 / 098531. These are preferably multilayer coatings comprising layers with a high refractive index (HI) and layers with a low refractive index (LI).

[0041] The structure and preparation of the anti-reflective coating are described in more detail in patent applications WO 2010 / 109154, WO 2011 / 080472 and WO 2012 / 153072.

[0042] The optical article according to the application can comprise a coating formed on the interference coating and capable of modifying its surface properties, such as a hydrophobic coating and / or an oleophobic coating (anti-fouling surface coating). These coatings are preferably deposited onto the outer layer of the interference coating. In general, its thickness is less than or equal to 10 nm, preferably ranging from 1 nm to 10 nm, more preferentially from 1 nm to 5 nm. The anti-fouling surface coating is generally a coating of the fluoro-silane or fluoro-silazane type, preferably comprising a fluoro- polyether moiety and more preferentially a perfluoro-polyether moiety. More detailed information on these coatings is disclosed in WO 2012 / 076714.

[0043] Instead of a hydrophobic coating, a hydrophilic coating providing anti-fog properties (anti-fog coating), or an anti-fog precursor coating providing anti-fog properties when associated with a surface activator can be used. Examples of such anti-fog precursor coatings are described in patent application WO2011 / 080472.

[0044] Coatings such as primers, hard coatings, anti-reflective coatings and anti-fouling coatings can be deposited using methods known in the art, including spin coating, dip coating, spray coating, vacuum evaporation, sputtering, chemical vapor deposition and lamination.

[0045] Typically, the optical article according to the application comprises a substrate which is successively coated with a shock-resistant primer layer, a wear- and / or scratch-resistant coating according to the application, a sub-layer and an interference coating, and a hydrophobic and / or oleophobic coating, or a hydrophilic coating providing anti-fog properties, or an anti-fog precursor coating.

[0046] The present hard coating can also be used as an external layer deposited directly on the substrate or on a functional coating. In another embodiment, it is used as a protective coating to prevent scratches or similar appearance defects resulting from the physical treatment of the underlying layer or substrate such as a photochromic layer, as disclosed in WO 2011 / 075128 or US6268055.

[0047] The coatings are preferably deposited directly on each other. These coatings can be deposited one after the other, or a stack of one or more coatings can be formed on the substrate, for example by lamination.

[0048] In one embodiment, the present optical article is prepared by forming a hard coating on the substrate in a first manufacturing point and forming the other coatings in a second manufacturing point.

[0049] Now, the inventive wear- and / or scratch-resistant coating according to the application prepared from a curable coating composition will be described.

[0050] According to the present application, the coating composition is deposited on the substrate in such a way that, after curing, the composition forms a wear- and / or scratch-resistant, antistatic coating having a thickness of preferably 1 pm or more, preferably from 1 to 100 pm, more preferably from 1 to 10 pm, or 3 to 9 pm, or 4 to 8 pm.

[0051] The wear-resistant coating is a coating which improves the wear resistance of the finished optical article compared to the same optical article without the wear-resistant coating.

[0052] The inventors have found that the coating of the present application provides wear- resistant properties to the article even if a layer having a significant thickness, i.e. more than 50 nm and preferably less than 1 micron, is deposited on the article.

[0053] The compositions described throughout this specification comprise one or more chemical compounds that are capable of forming a polymeric coating when subjected to radiation curing conditions. These materials include unsaturated silane compounds in combination with poly(meth)acrylate compounds. These coating materials can be used together and / or in combination with other materials to make a coating. The coating has sufficient abrasion and / or scratch resistance properties to provide a hard coating on a substrate.

[0054] The unsaturated silane used in the hard coating composition is preferably an unsaturated alkoxysilane, and preferably comprises a terminal ethylenic double bond. It can be, for example, a vinylsilane, an allylsilane, an acrylsilane, or a methacrylsilane. For stability of the composition, it is preferred to employ a non-hydrolyzed silane.

[0055] The unsaturated silane has reactivity unsaturation, i.e., the unsaturated portion of the silane can participate in a polymerization reaction. Silanes containing phenyl or aryl groups are not unsaturated silanes in the sense of this invention.

[0056] Without wishing to be bound by any theory, it is believed that the unsaturated silanes allow for increased abrasion resistance because they are monomers with functional groups that are tough in nature to provide some flexibility to the final coating without significantly affecting the crosslinking density.

[0057] Examples of vinylsilanes are vinyltris(2-methoxyethoxy)silane, vinyltriisobutoxy silane, vinyltris-t-butoxy silane, vinyltriphenyloxy silane, vinyltrimethoxy silane (the most preferred unsaturated silane), vinyltriisopropoxy silane, vinyltriethoxy silane, vinyltriacetoxy silane, vinyl dimethylethoxy silane, vinyl methyl diethoxy silane, vinyl methyl-dimethoxy silane, vinyl propyl trimethoxy silane, vinyl methyl diacetoxy-silane, vinyl bis(trimethylsiloxy) silane, and vinyl dimethoxy ethoxy silane. Acrylsilanes are not considered vinylsilanes.

[0058] Examples of allylsilanes are allyltrimethoxy silane, allyltriethoxy silane, allyl propyl trimethoxy silane, and allyl tris(trimethylsiloxy) silane.

[0059] Examples of acrylsilanes are 3-acryloyloxypropyl tris(trimethylsiloxy) silane, 3-acryloyloxy-propyl-trimethoxy silane, acryloyloxy-propyl methyl-dimethoxy-silane, 3-acryloyloxypropyl-methyl bis(trimethylsiloxy) silane, 3-acryloyloxypropyl-dimethyl methoxy silane, N-(3-acryloyloxy-2-hydroxypropyl)-3- aminopropyl-triethoxy silane.

[0060] Examples of methacrylic silanes are methacryloxypropyltris(vinyl dimethoxysiloxy)silane, methacryloxypropyltris(trimethylsiloxy)silane, methacryloxypropyltris(methoxyethoxy)silane, 3-methacryloxy-propyl-trimethoxysilane, 3-methacryloxy-propyl-pentamethyl-disiloxane, 3-methyl-acryloxy-propyl-methyl dimethoxysilane, 3-methacryloxy-propyl-methyl-diethoxysilane, 3-methacryloxy-propyl-dimethyl-methoxysilane, 3-methacryloxy-propyl-dimethyl-ethoxysilane, 3-methacryloxy-propyl-vinyl-trimethoxysilane, and 3-methacryloxy-propyl-bis(trimethylsiloxy)methylsilane.

[0061] The unsaturated silane compound is preferably a vinyl silane, more preferably a vinyl alkoxysilane, which can be selected from the group consisting of vinyl mono-, di-, and tri-alkoxysilanes. The vinyl silane material can be represented by the chemical formula R n Si(OR’) 4-n wherein R is a vinyl or substituted vinyl group, n is between 1 and 3, and R’ is a linear or branched alkyl or alkoxyalkyl group. In some cases, R’ can have 1 to 5 carbons.

[0062] The unsaturated silane compound can be employed at a weight concentration of 30% to 70%, 35% to 65%, 40% to 60%, or 45% to 50% relative to the weight of the composition. In one embodiment, the unsaturated silane compound is present in an amount higher than or equal to 30% or 33% by weight compared to the total weight of the composition.

[0063] Poly(meth)acrylate compounds comprising at least 6 (meth)acrylate groups are highly crosslinkable materials that can form covalent bonds between two or more polymer chains to form a crosslinkable coating. Non-limiting examples of such compounds include hexa(meth)acrylate compounds, such as dipentaerythritol hexaacrylate, silicone hexaacrylate, silicone hexamethacrylate, dipentaerythritol hexamethacrylate, tri-pentaerythritol octaacrylate, tri-pentaerythritol methacrylate, sorbitol hexaacrylate, sorbitol hexamethacrylate, urethane hexaacrylate compounds, and urethane hexamethacrylate compounds.

[0064] The composition can comprise from 8% to 70%, preferably from 25% to 65% by weight, more preferably from 40% to 60% or 45% to 50% by weight of a poly(meth)acrylate compound comprising at least 6 (meth)acrylate groups. In one embodiment, the poly(meth)acrylate compound is present in an amount higher than or equal to 33% by weight compared to the total weight of the composition.

[0065] In some embodiments, the weight ratio of the unsaturated silane to the poly(meth)acrylate compound present in the composition is in the range of 0.9 to 1.1, and may be 1:1.

[0066] The hard coating composition is prepared such that the at least one poly(meth)acrylate compound comprising at least six (meth)acrylate groups and the at least one unsaturated silane compound constitute at least 95% by weight of the polymerizable compound present in the composition. The two main components of the composition are sufficient to obtain satisfactory abrasion resistance and / or scratch resistance.

[0067] Therefore, the composition contains less than 5% by weight of a polymerizable compound such as (saturated) epoxysilane, for example γ-glycidoxypropyltrimethoxysilane, relative to the total weight of the composition.

[0068] To avoid damage such as breakage, the composition preferably contains less than 5% by weight of functionalized or unfunctionalized inorganic particles (or fillers), such as SiO2, and more preferably does not contain such compounds.

[0069] In one embodiment, the composition preferably comprises less than 5% by weight of a polymerizable compound containing epoxy groups relative to the total weight of the composition.

[0070] In particular, preferably, the composition of the present invention contains less than 5% colloidal silica by weight relative to the total weight of the composition, and more preferably contains no colloidal silica.

[0071] The coating composition contains at least one photoinitiator, preferably a photoinitiator that generates free radicals. A photoinitiator is a molecule that produces reactive substances (free radicals, cations, or anions) when exposed to radiation (UV or visible light).

[0072] Non-limiting examples of photoactivated free radical photoinitiators include, but are not limited to, xanthones, halogenated aromatic ketones, chloromethyl benzophenone, certain benzoyl ethers (e.g., alkylbenzoyl ethers), certain benzophenones, certain acetophenones and their derivatives such as diethoxyacetophenone and 2-hydroxy-2-methyl-1-phenylprop-1-one (e.g., 1173, finally registered with Burrough Wellcome, North Carolina, USA), dimethoxyphenyl acetophenone, benzyl acetophenone; hydroxy ketones, such as (1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one) 2959, last registered with BASF SE Company, 2,2-di-sec-butoxyacetophenone, 2,2-diethoxy-2-phenyl-acetophenone, 1-hydroxy-cyclohexyl-phenyl-ketone (e.g., 184), a-amino ketones (in particular those containing a benzoyl moiety, also known as a-aminoacetophenones, such as 2-methyl 1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one 907), (2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one 369)) and benzil ketals such as ethyl vanillin ether, isopropyl vanillin ether. In some embodiments, the free radical initiator can be selected from one or more of the following: a,a-dimethoxy-a-phenylacetophenone, and 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexyl phenyl ketone, and 2,2-dimethoxy-1,2-diphenylethan-1-one. Additional representative free radical photoinitiators include, but are not limited to, acylphosphine oxide types such as 2,4,6,-trimethylbenzoyl ethoxy diphenyl phosphine oxide, bisacyl phosphine oxides (BAPO), monoacyl and bisacyl phosphine oxides and sulfides such as phenyl bis(2,4,6-trimethylbenzoyl)-phosphine oxide (Lucerin® TPO) 819); and triacyl phosphine oxides. In some embodiments, a combination of free radical initiators is preferred.

[0073] The photoinitiator is preferably selected from the group consisting of benzophenone compounds, acetophenone compounds, monoacyl and bisacyl phosphine oxides, and combinations thereof.

[0074] The coating composition preferably comprises from 0.01 to 10 %, more preferably from 0.1 to 5 % or 1 to 5 % by weight of photoinitiator, relative to the total weight of the composition.

[0075] The curable composition according to the application can also contain, in conventional proportions, the various additives conventionally used in polymerisable compositions. These additives include additional initiators or catalysts, such as cationic initiators, accelerators, adhesion agents, solvents, wetting agents, stabilisers such as antioxidants, UV light absorbers, light stabilisers, anti-yellowing agents, fillers, adhesion promoters, dyes, photochromic agents, pigments, rheology modifiers, lubricants, ionic or non-ionic surfactants, fragrances, deodorants, doping agents such as organic acids, pH regulators. They are described, for example, in application WO2016 / 108061.

[0076] Depending on the monomers used (for example, an epoxy compound can be present in the composition), a cationic initiator, preferably a cationic photoinitiator, can be employed. The said compounds can also be used to catalyse the condensation of alkoxysilane groups (sol-gel process).

[0077] Non-limiting examples of cationic initiators include cationic initiators having or containing aromatic onium salts, salts of Group VA elements (e.g., phosphonium salts such as triphenylphenacylphosphonium hexafluorophosphate), salts of Group VIA elements (e.g., sulfonium salts such as triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluorophosphate, and triphenylsulfonium hexafluoroantimonate, triaryl sulfonium hexafluorophosphate, triaryl sulfonium hexafluoroantimonate), and salts of Group VIA elements (e.g., iodonium salts such as chlorodiphenyliodonium hexafluoroantimonate and diaryliodonium hexafluoroantimonate). Additional examples can be found in U.S. Patent No. 4,000,115 (e.g., phenyldiazonium hexafluorophosphate), U.S. Patent No. 4,058,401, U.S. Patent No. 4,069,055, U.S. Patent No. 4,101,513, and U.S. Patent No. 4,161,478. Preferred compounds are diaryliodonium salts and triarylsulfonium salts.

[0078] In one embodiment, the composition does not include any cationic initiator.

[0079] The coating composition can further include a solvent suitable for the above-described polymerizable compound. The solvent can be suitable for dispersing any component of the composition. In some embodiments, the solvent is a polar solvent such as any one or more of a primary alcohol and a diol. Non-limiting examples of solvents include methanol, ethanol, propanol, butanol, or a diol including propylene glycol, diol monoether, and any derivatives and variants thereof. Solvents can be used individually or in combination. In some cases, the solvent is anhydrous or substantially dry. In some embodiments, an environmentally friendly solvent is used. In some embodiments, the coating composition is free of solvent, or free of volatile solvent. Formulations having 100% solids are preferred in certain curing processes and equipment, such as those including UV curing.

[0080] In some embodiments, a surfactant can also be included. In one or more embodiments, a non-ionic surfactant is provided in the coating composition. A non-limiting example is a non-ionic fluorosurfactant containing at least one fluoroalkyl or polyfluoroalkyl group, an example of which is a fluoroaliphatic polymeric ester in a glycol solvent (e.g., dipropylene glycol monomethyl ether), such as Novec TM FC-4434 (3M Company, St. Paul, MN, USA) TMAnother non-limiting example is a fluorine-containing, organomodified polysiloxane in methoxypropanol (e.g., EFKA 3034, which has 50% solids, provided by BASF Company). A representative polymeric fluorocarbon compound containing 100% solids is EFKA 3600. Additional non-limiting examples include, but are not limited to, poly(alkyleneoxy)alkyl-ethers, poly(alkyleneoxy)alkyl-amines, poly(alkyleneoxy)alkyl-amides, polyethoxylated, polypropoxylated, or polyglycerolated fatty alcohols, polyethoxylated, polypropoxylated, or polyglycerolated fatty a-diols, polyethoxylated, polypropoxylated, or polyglycerolated fatty alkylphenols, and polyethoxylated, polypropoxylated, or polyglycerolated fatty acids, ethoxylated acetylenic diols, block copolymer types of compounds containing both hydrophilic and hydrophobic blocks (e.g., polyethylene oxide blocks, polypropylene oxide blocks), copolymers of poly(ethylene oxide) and poly(dimethylsiloxane), and surfactants incorporating sorbitan groups.

[0081] The coating composition can include from 0.05% to 1% by weight of surfactant, based on the total weight of the composition.

[0082] The coating composition can be applied to a substrate using known coating techniques to form a cured coating. The first coating can be formulated at 100% solids or solvent borne. In one aspect, the composition is formulated with minimal or in the absence of water. Non-limiting examples of depositing the coating composition onto a substrate include dip coating, spray coating, spin coating, gravure coating, flow coating, brushing, or rolling. Non-limiting examples of spin coating radiation curing processes, dip coating processes, or washing pretreatments performed prior to deposition can be found in application WO 2016 / 108061.

[0083] The coating composition can be applied directly to the surface of an untreated or pretreated substrate, a functional surface of a substrate, or alternatively to a surface of a carrier and then transferred to the substrate or its functionalized surface. The transfer process can include providing the coating composition to a carrier and then transferring from the carrier to the substrate, typically via a lamination process in between which an adhesive can or can not be required. Lamination refers to obtaining a permanent contact between a film containing at least one functional group (e.g., hydroxyl or olefin) and a surface containing the substrate. Lamination can include a heating and / or polymerization step to ultimately complete the adhesion between the layer from the carrier onto the substrate.

[0084] When the article includes an impact-resistant primer coating, the abrasion-resistant coating composition is preferably deposited on this impact-resistant primer coating.

[0085] After coating and optionally drying, the uncured composition is subjected to curing conditions sufficient to form a polymeric coating, preferably without any prior hydrolysis step. The term "cured" refers to the polymerization of the starting materials into a polymer. Cured includes conditions that allow some free functional groups to remain in the polymer matrix.

[0086] The curing conditions can include radiation curing (irradiation with light), which can include visible light and / or UV radiation, preferably UV curing. Thermal curing can also be combined with radiation curing. The composition can be subjected to temperature and light to obtain a temperature lower than or equal to the glass transition temperature (Tg) of the fully cured network, to obtain maximum properties and form a cured coating. In some embodiments, the curing temperature can be increased in a stepwise manner to control the curing rate and prevent excessive heat buildup from the exothermic reaction. In one embodiment, no thermal curing is employed to prepare the hard coating.

[0087] The method of preparing the article can include a drying step prior to the curing step, especially if an organic solvent has been used. In particular embodiments, the method does not include any step requiring heating, such that the temperature of the substrate is generally below 70°C during all manufacturing steps. In multiple particular embodiments, the temperature of the substrate is below 50°C during all manufacturing steps.

[0088] The curing step can include irradiating the coated layer with a UV radiation dose in the UV-C range (290 nm - 100 nm) ranging preferably from 0.15 J / cm 2 to 1.20 J / cm 2 The irradiation time preferably ranges from 1 second to 10 seconds. Naturally, a lower intensity bulb can be used for longer durations to achieve the same dose range.

[0089] In preferred embodiments, the method of preparing the article does not include any hydrolysis step prior to the curing step. Compositions with hydrolyzed or partially hydrolyzed alkoxysilanes can lead to premature condensation and formation of prepolymers before use, thereby increasing and destabilizing the viscosity of the composition.

[0090] In some embodiments, the composition is subjected to conditions that allow some free functional groups (e.g., hydroxyl or olefin) to remain in the composition. Without wishing to be bound by theory, it is believed that the functional groups bind to materials used for subsequent coatings (e.g., anti-reflective coatings) that adhere the subsequent coatings to the hard coating of the present application. This type of adhesion enables the lenses to be made without any primer or adhesive layer between any of the described hard coatings and the subsequent coatings.

[0091] The application also relates to an optical article having a substrate coated on at least one main face with a wear and / or scratch resistant coating obtained by curing a radiation-curable coating composition as described above.

[0092] The application further relates to a process for manufacturing said optical article, the process comprising:

[0093] - providing an optical article comprising a substrate having at least one main face,

[0094] - depositing on said at least one main face a layer of a radiation-curable coating composition as described above, and

[0095] - radiation-curing said composition to form a wear and / or scratch resistant coating.

[0096] The optical article substrate is preferably selected from the group consisting of thermoplastic substrates, thermoset substrates, and mineral substrates.

[0097] The following examples illustrate the application in more detail but in a non-limiting manner. Unless otherwise stated, all thicknesses disclosed in the present application relate to physical thicknesses. The percentages given in the tables are percentages by weight.

[0098] Examples

[0099] 1. Materials and Methods

[0100] The optical articles used in the examples include lenses substrates (refractive index of the material CR-39: 1.5), or polycarbonate lens substrates (refractive index: 1.594) having a diameter of 65 mm, a power of -2.00 diopters and a thickness of 1.2 mm.

[0101] Hand washing with mild detergent The substrates were then air dried. The washed and dried substrates were subjected to a chemical treatment comprising an ultrasonic washing with a mild caustic (NaOH) detergent followed by an ultrasonic neutralization with a diluted (5%) acetic acid solution followed by a deionized water rinse. The CR-39 lenses were then hand washed with a mild detergent solution, rinsed with deionized water and blown dry with filtered air before coating.

[0102] The polycarbonate substrates were first rinsed with deionized water under ultrasonics and then treated with a diluted amino-silane solution followed by a warm water rinse at 60°C. The substrates were hand washed with a mild detergent solution, rinsed with deionized water and then blown dry with filtered air before coating.

[0103] All radiation cured lenses were coated with a Headway Research benchtop spin coater and cured using a belt conveyor with UV / IR bulbs (H+ bulbs) from Fusion Systems under the conditions disclosed in WO 2016 / 178052.

[0104] These lenses were spin coated with the formulations elucidated below and subjected to radiation curing conditions. All coated lenses were left to rest overnight before further processing.

[0105] Hard coat thickness was 5.5-8 pm, except for Example CI (12 pm) and Example C4 (3.5 pm).

[0106] 2. Test Methods

[0107] Layer thickness was controlled by viscosity, application speed and spin-off speed for spin coating. For dip coating, thickness was controlled by viscosity and pull-off speed.

[0108] The haze value H of both the control and the optical article under test was measured by light transmission before and after the test according to the method of ASTM D1003-00 using a Haze-Guard Plus hazemeter (color difference meter) from BYK-Gardner, as disclosed in WO 2012 / 173596. Since haze is a measure of the percentage of transmitted light that is scattered more than 2.5° from the axis of the incident light, the lower the haze value, the lower the degree of turbidity.

[0109] According to ISTM 02-010, a 3M n°600 transparency tape was used to perform dry adhesion tests on coated articles, known as crosshatch tape peel adhesion tests, as disclosed in US 7476415 and US 2014 / 037964.

[0110] Determination of Scratch Resistance: Hand Steel Wool Test (HSW)

[0111] HSW test was performed only on the convex side of the lenses. A 24-hour waiting time was respected to perform the test.

[0112] The lens was hand sanded with steel wool perpendicular to the fiber direction, 5 passes back and forth with an amplitude of from 4 to 5 cm, maintaining a constant pressure of the index finger on the steel wool. The force exerted on the steel wool can be evaluated with a balance: the lens was fixed with tape on the balance plate and the normal force was applied with the index finger to press down the lens. This intensity was about 5 Kg during the first pass and about 2.5 Kg during the return pass. The lens was visually inspected and scored according to the following table. The higher the score, the more the lens was sanded. 1 is the best score and 5 is the worst.

[0113] Scratch Number >50 11-50 ≤10 Recorded Value 5 3 1 Risk Level High Acceptable Low

[0114] 3. Results

[0115] The following components were used in the inventive and comparative hardcoat compositions. Five different coating compositions were prepared.

[0116] Component Chemical Type Chemical Name Glymo Epoxy Silane Gamma-glycidoxypropyltrimethoxysilane VTMO Unsaturated Silane Vinyltrimethoxysilane M-600 Hexa Acrylate Dipentaerythritol Hexaacrylate GE-30 Aliphatic Epoxy Resin Trimethylolpropane Triglycidyl Ether SR-238 Diacrylate 1,6-Hexanediol Diacrylate UVI-6976 Cationic Photoinitiator Triaryl Sulfonium Hexafluoroantimonate UVI-6992 Cationic Photoinitiator Triaryl Sulfonium Hexafluorophosphate Darocur 1173 Radical Photoinitiator 2-Hydroxy-2-methyl-1-phenyl-propan-1-one Irgacure 819 Radical Photoinitiator Phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide EFKA-3034 Surfactant Fluorinated Surfactant

[0117]

[0118]

[0119] The compositions of comparative examples C1 and C3 do not contain any unsaturated silane, but other acrylic, epoxy, and / or alkoxy silane monomers.

[0120] The compositions of comparative examples C2 and C4 contain more than 5% by weight of polymerizable compounds that are neither unsaturated silanes nor poly(meth)acrylate compounds containing at least 6 (meth)acrylate groups.

[0121] The formulation of example 1 resulted in ultra-high scratch resistance results (no scratches observed after the hand steel wool test) compared to all other hardcoat compositions tested, and exhibited good adhesion to both CR-39 and PC substrates when tested after curing (dry) and after exposure to The coatings provided by the compositions of comparative examples C1 to C4 did not adhere well to the substrates, indicating that the presence of unsaturated silane and at least 95% by weight of poly(meth)acrylate containing at least 6 (meth)acrylate groups and unsaturated silane are essential features of the invention.

[0122] The coatings provided by the compositions of comparative examples C1 to C4 did not adhere well to the substrates, indicating that the presence of unsaturated silane and at least 95% by weight of poly(meth)acrylate containing at least 6 (meth)acrylate groups and unsaturated silane are essential features of the invention.

[0123] An additional test was performed using a mechanical steel wool test (000# steel wool) and a progressive load (gradually increasing weight) in order to compare the coating of Example 1 to a popular commercial or Essilor® UV-curable coating used on ophthalmic lenses. These lenses had a polycarbonate substrate coated on their front face.

[0124] The haze difference after testing the coated lenses was measured. The lower the haze, the less the coating was scratched.

[0125] The following hard coatings were tested: HT-850 (solvent-based tintable coating), HBX-1 (solventless non-tintable coating), EC-1244GS (tintable coating), UVNV (solventless tintable coating), ESS-UV (tintable coating). The results are shown below:

[0126]

[0127] It can be observed that the coating of Example 1 has an extremely high scratch resistance, exceeding the most famous UV-curable hard coatings.

Claims

1. A radiation-curable coating composition comprising: At least one poly(meth)acrylate compound containing at least six (meth)acrylate groups, At least one radiation-curable unsaturated silane compound, and At least one photoinitiator, The at least one poly(meth)acrylate compound comprising at least six (meth)acrylate groups and the at least one radiation-curable unsaturated silane compound constitute at least 95% by weight of the polymerizable compound present in the composition, and The radiation-curable unsaturated silane compound is present in an amount greater than or equal to 30% by weight relative to the total weight of the composition.

2. The coating composition according to claim 1, wherein, The at least one photoinitiator is a photoinitiator that generates free radicals.

3. The coating composition according to claim 1 or 2, wherein, The composition contains from 0.1% to 5% by weight of a photoinitiator relative to the total weight of the composition.

4. The coating composition according to claim 1 or 2, wherein, The photoinitiator is selected from the group consisting of: benzophenone compounds, acetophenone compounds, monoacyl and diacyl phosphine oxides, and combinations thereof.

5. The coating composition according to claim 1 or 2, wherein, The poly(meth)acrylate compound is a hexa(meth)acrylate compound.

6. The coating composition according to claim 5, wherein, The poly(meth)acrylate compound is dipentaerythritol hexaacrylate.

7. The coating composition according to claim 1 or 2, wherein, The radiation-curable unsaturated silane compound is a vinylsilane.

8. The coating composition according to claim 7, wherein, The radiation-curable unsaturated silane compound is a vinylalkoxysilane.

9. The coating composition according to claim 7, wherein, The vinylsilane is a vinylalkoxysilane selected from the group consisting of vinyl mono-, di-, and tri-alkoxysilanes.

10. The coating composition according to claim 9, wherein, The vinylsilane is vinyltrimethoxysilane.

11. The coating composition according to claim 1 or 2, wherein, The composition further comprises a surfactant at a weight of 0.05% to 1% relative to the total weight of the composition.

12. The coating composition according to claim 1 or 2, wherein, The composition does not contain any solvent.

13. The coating composition according to claim 1 or 2, wherein, The poly(meth)acrylate compound is present in an amount greater than or equal to 33% by weight relative to the total weight of the composition.

14. The coating composition according to claim 1 or 2, wherein, The radiation-curable unsaturated silane compound is present in an amount greater than or equal to 33% by weight relative to the total weight of the composition.

15. An optical article having a substrate coated with an abrasion-resistant and / or scratch-resistant coating on at least one main surface, said coating being obtained by curing a radiation-curable coating composition according to any one of the preceding claims.

16. The optical article according to claim 15, wherein, The coating has a thickness ranging from 1 to 10 μm.

17. The optical article according to claim 15, wherein, The optical product in question is an ophthalmic lens.

18. A method for manufacturing an optical article according to any one of claims 15 to 17, the method comprising: - Provide an optical article comprising a substrate having at least one main surface. - A layer of the radiation-curable coating composition according to any one of claims 1 to 14 is deposited on at least one main surface, and - The composition is radiation cured to form an abrasion-resistant and / or scratch-resistant coating.

19. The method according to claim 18, wherein, The optical product substrate is selected from the group consisting of thermoplastic substrates, thermosetting substrates, and mineral substrates.

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