Method for forming matte coating

Abstract

The invention relates to a method for coating a surface, comprising the steps of: applying a layer of a curable composition to the surface; irradiating the curable composition with a first radiation having a wavelength of from 100 to 280 nm to obtain a partially cured composition; and irradiating the partially cured composition with a second radiation comprising at least one wavelength longer than that of the first radiation and / or an electron beam to obtain a cured composition wherein the curable composition comprises particles of at least one actinic radiation curable compound and at least one polyamide. The invention also relates to a coating obtained by such a method and to an object comprising a surface covered with such a coating.

Description

Technical Field

[0001] The present invention relates to a process for coating surfaces based on curable compositions which result in a matte appearance, and to the coatings obtained by such a process. Background Art

[0002] Compositions that can be cured or crosslinked by actinic radiation are often used to form coatings on surfaces. In particular, they avoid the use of solvents and are capable of rapid crosslinking.

[0003] For some applications, a matte coating is desired. "Matte coating" refers to a coating having a specular gloss of less than 15 GU at 85°.

[0004] One known option for obtaining such a matte coating is to add a matting agent to the curable composition in an amount sufficient for some of the agent to appear at the surface of the coating, thereby creating roughness on said surface. Alternatively, matting can be obtained without the use of a matting agent by irradiating the coating composition with successive radiations at different wavelengths, so as to initially crosslink only a very low thickness of the coating at its surface to create the folds, and then crosslink the rest of the layer in a second stage.

[0005] However, the latter technique generally results in an uneven surface roughness, since highly folded areas alternate with areas that are barely folded, or the folds are oriented in a fan-shaped manner. The resulting coating then exhibits an uneven appearance, with matte areas and glossy areas, which distorts the appearance of the coating. In addition, these uneven coatings exhibit low stain resistance, since the areas with the fan-shaped folds retain dust and dirt.

[0006] US 2014 / 0371384 is a document relating to a method for mattifying a surface, which method comprises three radiation steps for crosslinking a coating agent applied to a substrate.

[0007] US 2016 / 0145449 is a document describing a photocrosslinkable composition comprising a crosslinkable component, a filler, a UV stabilizer, a photoinitiator and a component selected from a non-swellable filler and a swellable or soluble polymer.

[0008] US 2020 / 0024439 is a document relating to a cross-linked product produced by subjecting an acrylic composition to three radiation steps.

[0009] There is a real need to provide a process which allows obtaining uniform matte coatings which feature improved stain resistance and which can be used with a variety of crosslinkable components. Summary of the invention

[0010] The present invention firstly relates to a method for coating a surface, comprising the following steps:

[0011] - applying a layer of a curable composition to said surface;

[0012] - irradiating the curable composition with a first radiation having a wavelength of 100 to 280 nm to obtain a partially cured composition; and

[0013] - irradiating the partially cured composition with a second radiation comprising at least one wavelength longer than the wavelength of the first radiation and / or an electron beam to obtain a cured composition;

[0014] The curable composition comprises particles of at least one compound curable by actinic radiation and at least one polyamide.

[0015] In some embodiments, the curable composition comprises 0.01 wt % to 2 wt %, preferably 0.01 wt % to 1.5 wt % of particles of at least one polyamide, relative to the total weight of the composition.

[0016] In some embodiments, the particles of the at least one polyamide have a volume median diameter Dv50 less than or equal to 20 μm, preferably from 1 μm to 20 μm.

[0017] In some embodiments, the polyamide is selected from the group consisting of polyamide 12, polyamide 11, polyamide 10, polyamide 6, polyamide 6.10, polyamide 6.12, polyamide 6.6, polyamide 10.10, polyamide 10.12, and combinations thereof.

[0018] In some embodiments, at least one compound curable by actinic radiation is an ethylenically unsaturated compound, preferably a compound comprising at least one group selected from acrylate, methacrylate, cyanoacrylate, acrylamide, methacrylamide, styrene, maleate, fumarate, itaconate, allyl, propenyl, vinyl, methylidene malonate, and combinations thereof, more preferably a compound comprising at least one functional group selected from acrylate, methacrylate, and vinyl, and even more preferably a compound comprising at least one functional group selected from acrylate and methacrylate.

[0019] In some embodiments, the curable composition comprises at least one photoinitiator, and the at least one photoinitiator is preferably selected from benzoin, benzoin ether, acetophenone, benzil, benzil ketal, anthraquinone, phosphine oxide, α-hydroxy ketone, phenylglyoxylate, α-aminoketone, benzophenone, thioxanthone, xanthone, acridine derivatives, phenazine derivatives, quinoxaline derivatives, triazine derivatives and combinations thereof.

[0020] In some embodiments, the first radiation has a wavelength of 150 to 250 nm, preferably 150 to 200 nm, more preferably 168 to 180 nm, more preferably 172 to 175 nm.

[0021] In some embodiments, irradiating the curable composition with the first radiation is performed using an excimer lamp.

[0022] In some embodiments, the second radiation has a wavelength spectrum in the range of 100 nm to 900 nm, preferably 180 nm to 500 nm.

[0023] In some embodiments, the second radiation comprises at least one wavelength in the range of 285 to 900 nm, preferably in the range of 300 to 500 nm.

[0024] In some embodiments, the second radiation is emitted by an undoped mercury vapor lamp, a doped mercury vapor lamp, or an LED lamp, preferably with a wavelength in the range of 350 nm to 405 nm.

[0025] In some embodiments, the layer of curable composition applied to the surface has a thickness less than or equal to 100 μm, preferably less than or equal to 50 μm, more preferably less than or equal to 20 μm.

[0026] The invention also relates to a coating obtained by a process as described above.

[0027] The invention also relates to an object comprising a surface covered with a coating as described above.

[0028] The invention also relates to a composition comprising at least one compound curable by actinic radiation and 0.01% to 2% by weight, preferably 0.01% to 1.5% by weight, relative to the total weight of the composition, of particles of at least one polyamide.

[0029] The invention also relates to a coating based on the above-mentioned composition.

[0030] The invention also relates to the use of an excimer lamp for at least partially curing a curable composition comprising particles of at least one compound curable by actinic radiation and at least one polyamide.

[0031] The present invention is intended to meet the above needs. More specifically, the present invention provides a method for coating a surface, which allows the formation of a coating characterized by a regular and enhanced matte (extinction) property, an improved appearance and in particular a uniform appearance, and exhibits increased stain resistance, increased wear resistance and increased chemical resistance. In addition, the method according to the present invention allows a wide range of various curable compounds to obtain these advantageous properties.

[0032] This is achieved by incorporating polyamide particles into the curable composition and by using a method for curing said composition comprising a first radiation step for partially curing the composition and then a second radiation step for continuing to crosslink the composition. Without wishing to be bound by theory, the inventors believe that the polyamide particles dispersed in the curable composition create starting and ending points of folding at the surface of the layer of the curable composition, which points are created during the first radiation step, thereby enabling more effective control of the folding and therefore a better uniformity of the folding at the surface and therefore the gloss of the coating.

[0033] Furthermore, the above advantages can be achieved even with very small amounts of polyamide particles.Thus, in an advantageous embodiment, the polyamide particles can be used in the curable composition in very small amounts, more particularly in amounts that are smaller than conventionally used for matting agents. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] [ Figure 1 ] represents a micrograph obtained by scanning electron microscopy (SEM) of a coating obtained from the curable composition A as described in the examples hereinafter.

[0035] [ Figure 2 ] represents a micrograph obtained by scanning electron microscopy of a coating obtained from curable composition 3 as described in the examples hereinafter. DETAILED DESCRIPTION

[0036] The invention is now described in more detail in a non-limiting manner in the following description.

[0037] Unless otherwise indicated, all percentages concerning amounts are by mass.

[0038] In this text, an amount indicated for a given substance may apply to that substance according to all its definitions (as mentioned in this text), including more restricted definitions.

[0039] In the context of the present invention, the terms "curing" and "cross-linking" have the same meaning.

[0040] Curable composition

[0041] The curable composition used in the present invention is preferably liquid at 25° C. The curable composition may alternatively be in the form of a gel at 25° C. but in the form of a liquid at a higher temperature (eg, at 120° C.).

[0042] The curable composition used in the present invention comprises at least one compound curable by actinic radiation and particles of at least one polyamide. "Actinic radiation" generally refers to any electromagnetic and / or ionizing radiation capable of inducing a chemical reaction in a substance exposed to the radiation, and more particularly refers to radiation including ultraviolet (UV) radiation, visible light and electron beams.

[0043] The curable composition is advantageously a homogeneous dispersion. "Homogeneous dispersion" refers to a dispersion of polyamide particles in a liquid matrix comprising a curable compound. The homogeneity of the dispersion is thus macroscopic homogeneity (which means that the dispersion is homogeneous in appearance when observed with the naked eye), characterized in that the dispersion does not have a granular or phase-separated appearance.

[0044] The viscosity of the curable composition at 25° C. may be less than or equal to 100 000 mPa.s, preferably less than or equal to 50 000 mPa.s, more preferably less than or equal to 25 000 mPa.s, more preferably less than or equal to 10 000 mPa.s, more preferably less than or equal to 5000 mPa.s, as measured using a Brookfield DV-II viscometer with a No. 27 spindle (the spindle speed typically varies between 20 and 200 rpm, depending on the viscosity).

[0045] Compounds curable by actinic radiation

[0046] The curable composition according to the invention comprises one or more compounds curable by actinic radiation.The compounds curable by actinic radiation introduced into the curable composition according to the invention are collectively referred to as actinic radiation curable components.

[0047] Compounds curable by actinic radiation are particularly intended to be polymerized, in particular to be polymerized by free-radical polymerization.

[0048] Compounds curable by actinic radiation may in particular be ethylenically unsaturated compounds. In the sense of the present invention, "ethylenically unsaturated compounds" are compounds containing polymerizable carbon-carbon double bonds. A polymerizable carbon-carbon double bond is a carbon-carbon double bond that can react with another carbon-carbon double bond in a polymerization reaction. The carbon-carbon double bonds in benzene rings are not considered to be polymerizable carbon-carbon double bonds.

[0049] The ethylenically unsaturated compound may in particular be a compound comprising at least one group selected from acrylate, methacrylate, cyanoacrylate, acrylamide, methacrylamide, styrene, maleate, fumarate, itaconate, allyl, propenyl, vinyl, methylenemalonate and corresponding combinations, more preferably a compound comprising at least one functional group selected from acrylate, methacrylate, vinyl and combinations thereof, still more preferably a compound comprising at least one functional group selected from acrylate, methacrylate and combinations thereof.

[0050] The component curable by actinic radiation may in particular comprise or be a (meth)acrylate-functional compound. The component curable by actinic radiation may comprise or be a mixture of (meth)acrylate-functional compounds.

[0051] As used herein, the term "(meth)acrylate functionalized compound" refers to a compound comprising at least one (meth)acryloyloxy group, more particularly an acryloyloxy group. The term "(meth)acryloyloxy" encompasses acryloyloxy (-O-CO-CH=CH2) and methacryloyloxy (-O-CO-C(CH3)=CH2).

[0052] The total amount of (meth)acrylate-functional compounds in the actinic radiation-curable component can be 20% to 100% by weight, in particular 30% to 100% by weight, preferably 40% to 100% by weight, preferably 50% to 100% by weight, preferably 60% to 100% by weight, preferably 70% to 100% by weight, preferably 80% to 100% by weight, more preferably 90% to 100% by weight, based on the total weight of the actinic radiation-curable component. According to some embodiments, the actinic radiation-curable component does not contain polymerizable compounds other than (meth)acrylate-functional compounds.

[0053] The component curable by actinic radiation may in particular comprise or be a (meth)acrylate-functional compound selected from (meth)acrylate-functional monomers, (meth)acrylate-functional oligomers and mixtures thereof. More particularly, the component curable by actinic radiation may comprise or be at least one (meth)acrylate-functional monomer and / or at least one (meth)acrylate-functional oligomer. It is particularly advantageous if the component curable by actinic radiation comprises at least one (meth)acrylate-functional monomer and at least one (meth)acrylate-functional oligomer.

[0054] The component curable by actinic radiation may in particular comprise or be at least one (meth)acrylate-functional monomer.The component curable by actinic radiation may comprise (or be) a mixture of (meth)acrylate-functional monomers.

[0055] The (meth)acrylate functional monomer may have a molecular weight of less than 600 g / mol, specifically 70 to less than 550 g / mol, more specifically 80 to 450 g / mol, more specifically 90 to 350 g / mol.

[0056] The (meth)acrylate-functional monomer may contain 1 to 6 (meth)acryloyloxy groups, in particular 1 to 4 (meth)acryloyloxy groups.

[0057] The (meth)acrylate functional monomer may comprise a mixture of (meth)acrylate functional monomers having different functionalities. For example, the (meth)acrylate functional monomer may comprise or be a mixture of (or at least one) (meth)acrylate functional monomer containing a single acryloxy or methacryloyloxy group per molecule (referred to herein as a "mono (meth)acrylate functional monomer") and (or at least one) (meth)acrylate functional monomer containing 2 or more, preferably 2 to 6 acryloxy and / or methacryloyloxy groups per molecule (referred to herein as a "multi (meth)acrylate functional monomer").

[0058] The component curable by actinic radiation may in particular comprise or be at least one mono(meth)acrylate-functionalized monomer. The component curable by actinic radiation may in particular comprise a mixture of mono(meth)acrylate-functionalized monomers or may be a mixture of mono(meth)acrylate-functionalized monomers. The mono(meth)acrylate-functionalized monomers may advantageously serve as reactive diluents and reduce the viscosity of the curable composition according to the invention.

[0059] Examples of suitable mono(meth)acrylate functionalized monomers include, but are not limited to, (meth)acrylic acid, mono(meth)acrylates of aliphatic alcohols (the alcohol may be linear or branched and may be a monool, diol or polyol, provided that only one hydroxyl group is (meth)acrylated); mono(meth)acrylates of cycloaliphatic or heterocyclic alcohols; mono(meth)acrylates of aromatic alcohols (e.g., phenols, including alkylated phenols); mono(meth)acrylates of alkylaryl alcohols (e.g., benzyl alcohol); mono(meth)acrylates of oligomeric and polymeric glycols (such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol and polypropylene glycol); mono(meth)acrylates of monoalkyl ethers of glycols and oligomeric glycols; caprolactone mono(meth)acrylates; and also alkoxylated (e.g., ethoxylated and / or propoxylated) derivatives thereof; and mixtures thereof.

[0060] The component curable by actinic radiation may in particular comprise a mono(meth)acrylate-functionalized monomer selected from (meth)acrylic acid; methyl (meth)acrylate; ethyl (meth)acrylate; n-propyl (meth)acrylate; isopropyl (meth)acrylate; n-butyl (meth)acrylate; isobutyl (meth)acrylate; n-pentyl (meth)acrylate; n-hexyl (meth)acrylate; 2-ethylhexyl (meth)acrylate; n-octyl (meth)acrylate; isooctyl (meth)acrylate; n-decyl (meth)acrylate; isodecyl (meth)acrylate; n-dodecyl (meth)acrylate; Tridecyl (meth)acrylate; Tetradecyl (meth)acrylate; Hexadecyl (meth)acrylate; 2-hydroxyethyl (meth)acrylate; 2-hydroxypropyl (meth)acrylate; 3-hydroxypropyl (meth)acrylate; 4-hydroxybutyl (meth)acrylate; 2-methoxyethyl (meth)acrylate; 2-ethoxyethyl (meth)acrylate; 2-ethoxypropyl (meth)acrylate; 3-ethoxypropyl (meth)acrylate; Tetrahydrofurfuryl (meth)acrylate; 2-(2-ethoxyethoxy)ethyl (meth)acrylate; Cyclohexyl (meth)acrylate; (meth)acrylic acid Glycidyl (meth)acrylate; benzyl (meth)acrylate; 2-phenoxyethyl (meth)acrylate; phenol (meth)acrylate; nonylphenol (meth)acrylate; cyclic trimethylolpropane formal (meth)acrylate; isobornyl (meth)acrylate; tricyclodecane methanol (meth)acrylate; tert-butyl cyclohexyl (meth)acrylate; trimethylcyclohexyl (meth)acrylate; diethylene glycol monomethyl ether (meth)acrylate; diethylene glycol monobutyl ether (meth)acrylate; triethylene glycol monoethyl ether (meth)acrylate; polyethylene glycol monomethyl ether (meth)acrylate; hydroxyethyl-butylamino formate (meth)acrylate; 3-(2-hydroxyalkyl)oxazolidinone (meth)acrylate; (2,2-dimethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate; (2-ethyl-2-methyl-1,3-dioxolan-4-yl)methyl (meth)acrylate; 1,3-dioxan-5-yl (meth)acrylate; (1,3-dioxolan-4-yl)methyl (meth)acrylate; glycerol carbonate (meth)acrylate; and also alkoxylated (e.g., ethoxylated and / or propoxylated) derivatives thereof; and mixtures thereof.

[0061] The component curable by actinic radiation preferably comprises or is a mono(meth)acrylate-functional monomer selected from cyclohexyl acrylate, benzyl acrylate, 2-phenoxyethyl acrylate, nonylphenol acrylate, cyclic trimethylolpropane formal acrylate, isobornyl acrylate, tricyclodecane methanol acrylate, tert-butyl cyclohexyl acrylate, trimethyl cyclohexyl acrylate and mixtures thereof.

[0062] The component curable by actinic radiation may in particular comprise or be at least one multi(meth)acrylate-functional monomer.

[0063] Examples of multi-(meth)acrylate functional monomers include acrylates and methacrylates of polyols (organic compounds containing two or more hydroxyl groups per molecule, for example, 2 to 6 hydroxyl groups per molecule). Examples of suitable polyols are as follows: ethylene glycol, 1,2- or 1,3-propylene glycol, 1,2-, 1,3- or 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 10-decanediol, 1,12-dodecanediol, 2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 3,3-dimethyl-1, 5-pentanediol, neopentyl glycol, 2,4-diethyl-1,5-pentanediol, cyclohexanediol, cyclohexane-1,4-dimethanol, norbornane dimethanol, tricyclodecanediol, tricyclodecane dimethanol, bisphenol A, B, F or S, hydrogenated bisphenol A, B, F or S, trimethylolmethane, trimethylolethane, trimethylolpropane, di(trimethylolpropane), triethylolpropane, pentaerythritol, di(pentaerythritol), glycerol, di-, tri- or tetraglycerol, di-, tri- or tetraethylene glycol, di-, tri- or tetrapropylene glycol, di-, tri- or tetrapropylene glycol, di-, tri- or tetrabutylene glycol, one or more polyethylene glycols, one or more polypropylene glycols, one or more polytetramethylene glycols, one or more poly(ethylene glycol-co-propylene glycol), one or more sugar alcohols (more particularly erythritol, threitol, arabitol, xylitol, ribitol, mannitol, sorbitol, dulcitol, fucitol or iditol), one or more dianhydrohexitols (more particularly isosorbide, isomannite or isoiditol), tris(2-hydroxyethyl)isocyanurate, one or more polybutadiene polyols, and also alkoxylated (e.g. ethoxylated and / or propoxylated) derivatives thereof, derivatives obtained by ring-opening polymerization of a lactone (e.g. ε-caprolactone) initiated with one of the above polyols, and mixtures thereof. Such polyols may be fully or partially esterified (with (meth)acrylic acid, (meth)acrylic anhydride, (meth)acryloyl chloride, etc.), provided that they contain at least two (meth)acryloyloxy functional groups per molecule.

[0064] More particularly, the component curable by actinic radiation may in particular comprise or be a multi-(meth)acrylate functionalized monomer selected from bisphenol A di(meth)acrylate; hydrogenated bisphenol A di(meth)acrylate; ethylene glycol di(meth)acrylate; diethylene glycol di(meth)acrylate; triethylene glycol di(meth)acrylate; tetraethylene glycol di(meth)acrylate; polyethylene glycol di(meth)acrylate; propylene glycol di(meth)acrylate; dipropylene glycol di(meth)acrylate; tripropylene glycol di(meth)acrylate; tetrapropylene glycol di(meth)acrylate; polypropylene glycol di(meth)acrylate. acrylate; polytetramethylene glycol di(meth)acrylate; 1,2-butanediol di(meth)acrylate; 2,3-butanediol di(meth)acrylate; 1,3-butanediol di(meth)acrylate; 1,4-butanediol di(meth)acrylate; 1,5-pentanediol di(meth)acrylate; 1,6-hexanediol di(meth)acrylate; 1,8-octanediol di(meth)acrylate; 1,9-nonanediol di(meth)acrylate; 1,10-decanediol di(meth)acrylate; 1,12-dodecanediol di(meth)acrylate; 3-methyl-1,5-pentanediol di(meth)acrylate 2-Methyl-2,4-pentanediol di(meth)acrylate; cyclohexane-1,4-dimethanol di(meth)acrylate; tricyclodecane dimethanol di(meth)acrylate; glycerol di(meth)acrylate; glycerol tri(meth)acrylate; trimethylolethane tri(meth)acrylate; trimethylolethane di(meth)acrylate; trimethylolpropane tri(meth)acrylate; trimethylolpropane di(meth)acrylate; pentaerythritol di(meth)acrylate; pentaerythritol tri(meth)acrylate (meth)acrylates; pentaerythritol tetra(meth)acrylate; di(trimethylolpropane) di(meth)acrylate; di(trimethylolpropane) tri(meth)acrylate; di(trimethylolpropane) tetra(meth)acrylate; sorbitol penta(meth)acrylate; di(pentaerythritol) tetra(meth)acrylate; di(pentaerythritol) penta(meth)acrylate; di(pentaerythritol) hexa(meth)acrylate; tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate; and also alkoxylated (e.g., ethoxylated and / or propoxylated) derivatives thereof; and mixtures thereof.

[0065] The component curable by actinic radiation preferably comprises or is a poly(meth)acrylate-functional monomer selected from 1,6-hexanediol diacrylate, 1,10-decanediol acrylate, 3-methyl-1,5-pentanediol diacrylate, neopentyl glycol diacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane triacrylate, di(trimethylolpropane) tetraacrylate, pentaerythritol tetraacrylate, di(pentaerythritol) pentaacrylate and mixtures thereof.

[0066] The component curable by actinic radiation may comprise 0 to 100 wt %, particularly 5 to 100 wt %, more particularly 10 to 100 wt %, more particularly 15 to 100 wt %, more particularly 20 to 95 wt %, more particularly 25 to 95 wt %, more particularly 30 to 95 wt %, more particularly 35 to 90 wt %, more particularly 40 to 90 wt %, still more particularly 50 to 90 wt %, based on the weight of the component curable by actinic radiation, of (meth)acrylate-functional monomers. Thus, the component curable by actinic radiation may comprise 0% to 60% by weight, preferably 5% to 60% by weight, preferably 10% to 60% by weight, preferably 15% to 60% by weight, preferably 20% to 60% by weight, preferably 25% to 60% by weight, preferably 30% to 60% by weight, preferably 35% to 60% by weight, preferably 40% to 60% by weight, more preferably 45% to 60% by weight of (meth)acrylate-functional monomers, based on the weight of the component curable by actinic radiation. As a variant, the component curable by actinic radiation may comprise 60% to 100% by weight, preferably 65% ​​to 100% by weight, preferably 70% to 100% by weight, preferably 75% to 100% by weight, preferably 80% to 100% by weight, preferably 85% to 100% by weight, preferably 90% to 100% by weight, more preferably 95% to 100% by weight, based on the weight of the component curable by actinic radiation, of (meth)acrylate-functional monomers.

[0067] The component curable by actinic radiation may in particular comprise or be at least one (meth)acrylate-functional oligomer.The component curable by actinic radiation may comprise a mixture of (meth)acrylate-functional oligomers or a mixture of (meth)acrylate-functional oligomers.

[0068] The (meth)acrylate functionalized oligomer may be selected so as to enhance the flexibility, strength and / or modulus, as well as other properties, of the product obtained by polymerizing the curable composition according to the present invention.

[0069] The (meth)acrylate functionalized oligomer may have 1 to 18 (meth)acryloyloxy groups, specifically 2 to 6 (meth)acryloyloxy groups, and more specifically 2 to 6 acryloyloxy groups.

[0070] The (meth)acrylate functionalized oligomer may have a number average molecular weight greater than or equal to 600 g / mol, specifically 800 to 15000 g / mol, more specifically 1000 to 5000 g / mol. The number average molecular weight of the (meth)acrylate functionalized oligomer may be measured by gel permeation chromatography (GPC).

[0071] In particular, the component curable by actinic radiation may comprise or be a (meth)acrylate-functionalized oligomer selected from the group consisting of (meth)acrylate-functionalized urethane oligomers, (meth)acrylate-functionalized epoxy oligomers, (meth)acrylate-functionalized polyether oligomers, (meth)acrylate-functionalized polyester oligomers, (meth)acrylate-functionalized (meth)acrylic oligomers, (meth)acrylate-functionalized polydiene oligomers, (meth)acrylate-functionalized polycarbonate oligomers, (meth)acrylate-functionalized polyamide oligomers, and mixtures thereof.

[0072] (Meth)acrylate functionalized urethane oligomers suitable for use in the curable compositions of the present invention include urethanes based on at least one polyol, at least one polyisocyanate, and at least one hydroxyl-functional and (meth)acrylate-functionalized compound (also referred to as hydroxyl-functional (meth)acrylate). The (meth)acrylate functionalized urethane oligomers can be prepared by reacting a polyisocyanate (e.g., an aliphatic, alicyclic, heterocyclic or aromatic diisocyanate or triisocyanate) with a polyol (particularly a polyester polyol, a polyether polyol, a polycarbonate polyol, a polycaprolactone polyol, a polyorganosiloxane polyol, a polydiene polyol such as a polybutadiene polyol, or a corresponding combination) to form an isocyanate group-terminated oligomer, which is then reacted with a hydroxyl-functional (meth)acrylate (such as hydroxyethyl (meth)acrylate) to provide a terminal (meth)acrylate group. For example, a (meth)acrylate functionalized urethane oligomer may contain two, three, four or more (meth)acrylate functional groups per molecule. Other addition sequences may also be used to prepare (meth)acrylate functionalized urethane oligomers. For example, a hydroxyl functionalized (meth)acrylate may first be reacted with a polyisocyanate to obtain an isocyanate functionalized (meth)acrylate, which may then be reacted with a polyol. As a variant, all components may be combined and reacted simultaneously.

[0073] Examples of suitable (meth)acrylate functionalized epoxy oligomers include the reaction products of (meth)acrylic acid (or the corresponding synthetic equivalents, such as acid chlorides, alkyl esters or anhydrides) and epoxy resins containing at least one epoxy group, in particular at least one group selected from glycidyl ethers, glycidyl esters and combinations thereof. The epoxy resins may be selected in particular from bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, brominated bisphenol S diglycidyl ether, epoxy novolac resins, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate , 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-1,4-dioxane, bis(3,4-epoxycyclohexylmethyl)adipate, vinylcyclohexene oxide, 4-vinylepoxycyclohexane, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, 3,4-epoxy-6-methylcyclohexyl-3',4'-epoxy-6'-methylcyclohexanecarboxylate, methylenebis(3,4- cyclohexene oxide), dicyclopentadiene diepoxide, ethylene glycol bis (3,4-epoxycyclohexyl methyl) ether, ethylene bis (3,4-epoxycyclohexane carboxylate), 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, by adding one or more alkylene oxides to aliphatic polyols ( Such as ethylene glycol, propylene glycol and glycerol), polyglycidyl ethers of polyether polyols obtained on polyols (such as ethylene glycol, propylene glycol and glycerol), diglycidyl esters of long-chain aliphatic dibasic acids, monoglycidyl ethers of aliphatic higher alcohols, butylphenol, cresol, phenol or monoglycidyl ethers of polyether alcohols obtained by adding alkylene oxides to these compounds, glycidyl esters of higher fatty acids, epoxidized soybean oil, epoxybutyl stearic acid, epoxyoctyl stearic acid, epoxidized linseed oil, epoxidized polybutadiene, etc.

[0074] Suitable (meth)acrylate functionalized polyether oligomers include, but are not limited to, the reaction product of (meth)acrylic acid (or the corresponding synthetic equivalent, such as an acid chloride, an alkyl ester or anhydride) and at least one polyether alcohol corresponding to a polyether polyol (e.g., polyethylene glycol, polypropylene glycol, polytetramethylene glycol or a copolymer thereof). Suitable polyether alcohols can be straight or branched chain substances containing ether bonds and terminal hydroxyl groups. Polyether alcohols can be prepared by ring-opening polymerization of cyclic ethers such as tetrahydrofuran or alkylene oxides (e.g., ethylene oxide and / or propylene oxide) with a starting molecule. Suitable starting molecules include water, polyhydroxyl functionalized materials, polyester polyols and amines.

[0075] The (meth)acrylate functionalized polyester oligomers given by way of example include the reaction products of (meth)acrylic acid (or the corresponding synthetic equivalents, such as acid chlorides, alkyl esters or anhydrides) and hydroxyl-terminated polyester polyols. The reaction process can be carried out so that all or substantially all of the hydroxyl groups of the polyester polyol have been (meth)acrylated, especially in the case where the polyester polyol is difunctional. The polyester polyol can be prepared by the polycondensation reaction of a polyhydroxy-functional component, especially a diol, and a poly(carboxylic acid)-functional component, especially a dicarboxylic acid and anhydride. The polyhydroxy-functional component and the poly(carboxylic acid)-functional component can each have a linear, branched, alicyclic or aromatic structure and can be used alone or as a mixture.

[0076] Suitable (meth)acrylate functionalized (meth)acrylic oligomers (sometimes also referred to in the art as "acrylic oligomers") include oligomers that can be described as materials having a (meth)acrylic backbone that is functionalized with one or more (meth)acrylate groups (which can be located at the end of the oligomer or pendent to the (meth)acrylic backbone). The (meth)acrylic backbone can be a homopolymer, a random copolymer, or a block copolymer composed of repeating units of (meth)acrylic monomers. The (meth)acrylic monomers can be (meth)acrylic esters of any monomer type, such as C1-C6 alkyl (meth)acrylates and / or functionalized (meth)acrylates, such as (meth)acrylates with hydroxyl, carboxylic acid, and / or epoxy groups. (Meth)acrylate functionalized (meth)acrylic oligomers can be prepared by any procedure known in the art, such as oligomerization of monomers, at least some of which are functionalized with hydroxyl, carboxylic acid and / or epoxy groups (e.g., hydroxyalkyl (meth)acrylates, (meth)acrylic acid, glycidyl (meth)acrylate) to obtain a functionalized oligomer intermediate, which is then reacted with one or more (meth)acrylate group-containing reactants to introduce the desired (meth)acrylate functionality.

[0077] (Meth)acrylate functionalized polydiene oligomers given by way of example include the reaction products of (meth)acrylic acid (or the corresponding synthetic equivalents, such as acid chlorides, alkyl esters or anhydrides) and hydroxyl terminated polydiene polyols, especially hydroxyl terminated polybutadiene polyols.

[0078] (Meth)acrylate functionalized polycarbonate oligomers given by way of example include the reaction product of (meth)acrylic acid (or the corresponding synthetic equivalent, such as the acid chloride, alkyl ester or anhydride) and a hydroxyl terminated polycarbonate polyol.

[0079] The (meth)acrylate functionalized polyamide oligomers given by way of example include the reaction product of (meth)acrylic acid (or the corresponding synthetic equivalents, such as acid chlorides, alkyl esters or anhydrides) and hydroxyl terminated polyamide polyols.

[0080] The component curable by actinic radiation preferably comprises or is a (meth)acrylate functionalized oligomer selected from the group consisting of (meth)acrylate functionalized urethane oligomers, (meth)acrylate functionalized epoxy oligomers, (meth)acrylate functionalized polyester oligomers, and mixtures thereof. Particularly preferred (meth)acrylate functionalized oligomers for use in the present invention include those sold by Sartomer under the trade names CN9200, CN9210, CN9276CN9301, CN963B80, CN964A85, CN965, CN981, CN991, CN996, CN998B80, CN104, CN203, CN2203EU, CN2295EU, CN2303EU, CN2505, and mixtures thereof.

[0081] The component curable by actinic radiation may contain 0% to 100% by weight, particularly 5% to 100% by weight, more particularly 10% to 100% by weight, more particularly 15% to 100% by weight, more particularly 20% to 95% by weight, more particularly 25% to 95% by weight, more particularly 30% to 95% by weight, more particularly 35% to 90% by weight, more particularly 40% to 90% by weight, and even more particularly 50% to 90% by weight of (meth)acrylate-functional oligomers, based on the weight of the component curable by actinic radiation. In particular, the component curable by actinic radiation may contain 0% to 60% by weight, preferably 5% to 60% by weight, preferably 10% to 60% by weight, preferably 15% to 60% by weight, preferably 20% to 60% by weight, preferably 25% to 60% by weight, preferably 30% to 60% by weight, preferably 35% to 60% by weight, preferably 40% to 60% by weight, and more preferably 45% to 60% by weight of (meth)acrylate-functional oligomers, based on the weight of the component curable by actinic radiation. As a variant, the component curable by actinic radiation may comprise 60% to 100% by weight, preferably 65% ​​to 100% by weight, preferably 70% to 100% by weight, preferably 75% to 100% by weight, preferably 80% to 100% by weight, preferably 85% to 100% by weight, preferably 90% to 100% by weight, more preferably 95% to 100% by weight, based on the weight of the component curable by actinic radiation, of (meth)acrylate-functional oligomers.

[0082] The components curable by actinic radiation advantageously comprise:

[0083] - 10% to 90% by weight, preferably 20% to 80% by weight, more preferably 30% to 70% by weight, more preferably 40% to 60% by weight of (meth)acrylate-functional monomers; and

[0084] - 10% to 90% by weight, preferably 20% to 80% by weight, more preferably 30% to 70% by weight, more preferably 40% to 60% by weight of (meth)acrylate-functional oligomers;

[0085] The weight % are expressed relative to the weight of the component curable by actinic radiation.

[0086] The amount of actinic radiation-curable components in the curable composition is preferably from 50% to 99.99% by weight, more preferably from 80% to 99.99% by weight, preferably from 90% to 99.99% by weight, still more preferably from 95% to 99.99% by weight.

[0087] Polyamide granules

[0088] The curable composition comprises particles of at least one polyamide. The polyamide particles are in particular a powder.

[0089] According to one embodiment, the particles consist of one or more polyamides.

[0090] The polyamide may be a homopolyamide and / or a copolyamide. It may consist solely of polyamide or may contain one or more blocks of another type, for example selected from polyether blocks, polyester blocks, polysiloxane blocks (e.g. polydimethylsiloxane (or PDMS) blocks), polyolefin blocks, polycarbonate blocks and mixtures thereof.

[0091] The term "polyamide" is intended to mean a polymer comprising at least one product of the polymerization of one or more monomers selected from:

[0092] - monomers of amino acid or aminocarboxylic acid type, and preferably α,ω-aminocarboxylic acid;

[0093] - lactam-type monomers containing 3 to 18 carbon atoms in the main ring and which may be substituted;

[0094] - "diamine.diacid" type monomers derived from the reaction between an aliphatic diamine containing 2 to 36 carbon atoms, preferably 4 to 18 carbon atoms, and a dicarboxylic acid containing 4 to 36 carbon atoms, preferably 4 to 18 carbon atoms; and

[0095] - mixtures thereof, in the case of a mixture between monomers of amino acid type and monomers of lactam type, the monomers containing different carbon numbers.

[0096] In this specification, the term "monomer" is understood to mean "repeating unit". In practice, a special case is the repeating unit of a polyamide (PA) consisting of a combination of a diacid and a diamine. It is considered to be a combination of a diamine and a diacid, i.e. a diamine.diacid pair (in equimolar amounts), which corresponds to a monomer. This is explained by the fact that individually, a diacid or a diamine is only a structural unit which is not sufficient by itself for polymerization.

[0097] When the polyamide is a homopolyamide, it comprises the polymerization product of a single monomer as defined above. When the polyamide is a copolyamide, it comprises the polymerization product of at least two different monomers as defined above. As examples of copolyamides formed by the various types of monomers mentioned above, mention may be made of copolyamides produced by the condensation of at least two α,ω-aminocarboxylic acids or two lactams or one lactam and one α,ω-aminocarboxylic acid. Mention may also be made of copolyamides produced by the condensation of at least one α,ω-aminocarboxylic acid (or lactam), at least one diamine and at least one dicarboxylic acid. Mention may also be made of copolyamides produced by the condensation of aliphatic diamines with aliphatic dicarboxylic acids and at least one other monomer selected from aliphatic diamines different from the previous aliphatic diamine and aliphatic diacids different from the previous aliphatic diacid.

[0098] Amino acid type monomers:

[0099] As examples of α,ω-amino acids, mention may be made of those containing 4 to 18 carbon atoms, such as aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, N-heptyl-11-aminoundecanoic acid and 12-aminododecanoic acid.

[0100] Lactam type monomers:

[0101] As examples of lactams, mention may be made of those containing from 3 to 18 carbon atoms in the main ring and which may be substituted. Mention may be made, for example, of β,β-dimethylpropiolactam, α,α-dimethylpropiolactam, valerolactam, caprolactam (also known as lactam 6), capryllactam (also known as lactam 8), enantholactam and laurolactam (also known as lactam 12).

[0102] "Diamine. Diacid" type monomers:

[0103] Examples of dicarboxylic acids include acids having 4 to 36 carbon atoms, preferably 4 to 18 carbon atoms. Mention may be made, for example, of adipic acid, sebacic acid, azelaic acid, suberic acid, isophthalic acid, succinic acid, 1,4-cyclohexyldicarboxylic acid, terephthalic acid, the sodium or lithium salts of sulfoisophthalic acid, dimer fatty acids (these dimer fatty acids have a dimer content of at least 98% by weight and are preferably hydrogenated), dodecanedioic acid HOOC-(CH2) 10 -COOH and tetradecanedioic acid.

[0104] The term "fatty acid dimer" or "dimerized fatty acid" is more particularly understood to mean the product of the dimerization reaction of fatty acids (usually containing 18 carbon atoms, usually a mixture of oleic and / or linoleic acids). It is preferably a mixture comprising 0-15% by weight of C18 monoacids, 60-99% by weight of C36 diacids and 0.2-35% by weight of triacids or C54 or higher polyacids.

[0105] Examples of diamines include aliphatic diamines having 2 to 36 atoms, preferably 4 to 18 atoms, more preferably 6 to 12 carbon atoms, and which may be aromatic and / or saturated cyclic. Examples that may be mentioned include hexamethylenediamine, piperazine (abbreviated as "Pip"), aminoethylenepiperazine, tetramethylenediamine, octamethylenediamine, 1,10-decamethylenediamine, dodecamethylenediamine, 1,5-diaminohexane, 2,2,4-trimethyl-1,6-diaminohexane, diamine polyols, isophoronediamine (IPD), methylpentamethylenediamine (MPMD), bis(aminocyclohexyl)methane (BACM), bis(3-methyl-4-aminocyclohexyl)methane (BMACM), meta-xylylenediamine, and bis-p-aminocyclohexylmethane.

[0106] "Diamine.diacids" more particularly include those resulting from the condensation of 1,6-hexamethylenediamine with dicarboxylic acids having from 6 to 36 carbon atoms, especially the following monomers: 6.6, 6.10, 6.11, 6.12, 6.14 and 6.18, and those resulting from the condensation of 1,10-decamethylenediamine with diacids having from 6 to 36 carbon atoms, especially the following monomers: 10.10, 10.12, 10.14 and 10.18. In the numerical notation XY, X represents the number of carbon atoms derived from the diamine residue and Y represents the number of carbon atoms derived from the diacid residue, which is conventional.

[0107] The polyamide preferably comprises at least one of the following monomers: 4.6, 4.T, 5.6, 5.9, 5.10, 5.12, 5.13, 5.14, 5.16, 5.18, 5.36, 6, 6.6, 6.9, 6.10, 6.12, 6.13, 6.14, 6.16, 6.18, 6.36, 6.T, 9, 10.6, 10.9, 10.10, 10.12, 10.13, 10.14, 10.16, 10.18, 10.36, 10.T, 11, 12, 12.6, 12.9, 12.10, 12.12, 12.13, 12.14, 12.16, 12.18, 12.36, 12.T, and mixtures thereof.

[0108] Advantageously, the polyamide used in the present invention is the polyamide (or comprises polyamide blocks): PA 6, PA 10, PA 11, PA 12, PA 5.4, PA 5.9, PA 5.10, PA 5.12, PA 5.13, PA 5.14, PA 5.16, PA 5.18, PA 5.36, PA 6.4, PA 6.9, PA 6.10, PA 6.12, PA 6.13, PA 6.14, PA 6.16, PA 6.18, PA 6.36, PA 10.4, PA 10.9, PA 10.10, PA 10.12, PA 10.13, PA 10.14, PA 10.16, PA 10.18, PA 10.36, PA 10.4, PA 10.9, PA 10.10, PA 10.12, PA 10.13, PA 10.14, PA 10.16, PA 10.18, PA 10.36. 14, PA 12.16, PA 12.18, PA 12.36, PA 12.T, PA 6.6 / 6, PA 6.6 / 6.10 / 11 / 12, PA 10.10 / 11, PA 10.10 / 12, PA 10.10 / 14, PA 10.12 / 11, PA 10.12 / 12, PA 10.12 / 14, or mixtures or copolymers thereof. In the PA X notation, X represents the number of carbon atoms derived from an amino acid residue or a lactam residue. The notations PA X / Y, PA X / Y / Z, etc. relate to copolyamides, wherein X, Y, Z, etc. represent homopolyamide units as described above.

[0109] Preferably, the polyamide according to the invention is selected from PA 11, PA 12, PA 6, PA 6.X1, PA 10, PA 10.X2, PA 10.X3 / Y1 or a combination thereof. Preferably, from the above list, X1 is selected from 10, 12, 14 or 18. Preferably, from the above list, X2 is selected from 10, 12 or 14. Preferably, from the above list, X3 is selected from 10 or 12. Preferably, from the above list, Y1 is selected from 11, 12 or 14.

[0110] Advantageously, the polyamide of the powder is one (or more) homopolyamides.

[0111] More preferably, the polyamide is selected from the group consisting of polyamide 12, polyamide 11, polyamide 10, polyamide 6, polyamide 6.10, polyamide 6.12, polyamide 6.6, polyamide 10.10, polyamide 10.12 and combinations thereof. Particularly preferably, the polyamide is polyamide 12.

[0112] The polyamide may alternatively be a copolyamide. These include copolymers of caprolactam and lauryl lactam (PA 6 / 12), copolymers of caprolactam, adipic acid and hexamethylenediamine (PA 6 / 6.6), copolymers of caprolactam, lauryl lactam, adipic acid and hexamethylenediamine (PA 6 / 12 / 6.6), copolymers of caprolactam, lauryl lactam, 11-aminoundecanoic acid, azelaic acid and hexamethylenediamine (PA 6 / 6.9 / 11 / 12), copolymers of caprolactam, lauryl lactam, 11-aminoundecanoic acid, adipic acid and hexamethylenediamine (PA 6 / 6.6 / 11 / 12), copolymers of lauryl lactam, azelaic acid and hexamethylenediamine (PA 6.9 / 12), copolymers of 11-aminoundecanoic acid, terephthalic acid and 1,10-decamethylenediamine (PA 11 / 10.T).

[0113] The polyamide according to the invention may be a mixture of polyamides, for example a mixture of aliphatic polyamide and semiaromatic polyamide or a mixture of aliphatic polyamide and cycloaliphatic polyamide. When the polyamide is a mixture of polyamides, the polyamide particles may consist of a mixture of particles of the individual polyamides, or each particle may contain a mixture of polyamides.

[0114] Advantageously, the volume median diameter Dv50 of the polyamide particles is less than or equal to 20 μm, preferably from 1 to 20 μm, more preferably from 5 to 20 μm. More particularly, the volume median diameter Dv50 of the polyamide particles may be from 1 to 5 μm, or from 5 to 10 μm, or from 10 to 15 μm, or from 15 to 20 μm. Dv50 corresponds to the particle size at the 50th percentile (by volume) of the cumulative particle size distribution. It can be determined according to standard ISO 9276-parts 1 to 6.

[0115] The polyamide powder according to the present invention can be prepared by grinding a polyamide in solid form (e.g., in pellet form). Polyamide, particularly when it comprises a mixture of two or more polyamides, can preferably be melted and optionally mixed, such as in a compounding machine. Subsequently, it is ground after solidification. Grinding can be accomplished by any means, and can more particularly be selected from hammer milling, knife milling, disc milling, air jet grinding and cryogenic grinding. The powder preparation method may also include the step of selecting powder particles with a desired particle size.

[0116] Relative to the gross weight of the composition, the curable composition preferably comprises polyamide particles in an amount of 0.01 wt % to 2 wt %, more preferably 0.01 wt % to 1.5 wt %, more preferably 0.05 wt % to 1.5 wt %, and still more preferably 0.1 wt % to 1.5 wt %. In particular, the polyamide particles may be present in an amount lower than the amount of matte agents typically used to obtain a matte effect. In some embodiments, the curable composition may comprise polyamide particles in an amount of 0.01 wt % to 0.05 wt %, or 0.05 wt % to 0.1 wt %, or 0.1 wt % to 0.2 wt %, or 0.2 wt % to 0.3 wt %, or 0.3 wt % to 0.5 wt %, or 0.5 wt % to 0.8 wt %, or 0.8 wt % to 1 wt %, or 1 wt % to 1.2 wt %, or 1.2 wt % to 1.5 wt %, or 1.5 wt % to 1.7 wt %, or 1.7 wt % to 2 wt %.

[0117] Photoinitiator

[0118] The curable composition according to the present invention may comprise at least one photoinitiator. The composition, more particularly one or more compounds curable by actinic radiation, in this case preferably by radiation energy (visible light and / or ultraviolet light). A photoinitiator may be considered to be any type of substance which, when exposed to radiation (e.g., actinic radiation), forms a substance that initiates the reaction and curing of the organic polymeric material present in the curable composition. Photoinitiators suitable for use in the present invention include free radical photoinitiators, cationic photoinitiators, and combinations thereof.

[0119] Polymerization initiators that act by free radical pathways are substances that form free radicals when they are irradiated. Preferably, free radical photoinitiators are used. Non-limiting examples of free radical photoinitiators suitable for use in curable compositions of the present invention include benzoin, benzoin ethers, acetophenones, benzil, benzil ketals, anthraquinones, phosphine oxides, α-hydroxy ketones, phenylglyoxylic acid esters, α-aminoketones, benzophenones, thioxanthones, xanthones, acridine derivatives, phenazine derivatives, quinoxaline derivatives, triazine derivatives and mixtures thereof.

[0120] When the photoinitiator is present in the curable composition, it is preferably present in an amount of up to 15% by weight, more particularly 0.05% to 15% by weight, based on the total weight of the curable composition. For example, the curable composition may advantageously contain 0.1% to 10% by weight of the photoinitiator, based on the total weight of the curable composition. In some embodiments, the curable composition contains 0.05% to 0.5% by weight, or 0.5% to 5% by weight, or 5% to 10% by weight, or 10% to 15% by weight of the photoinitiator, relative to the total weight of the composition.

[0121] Non-reactive solvent

[0122] The curable composition is preferably free or substantially free of non-reactive solvents. As used herein, the term "non-reactive solvent" refers to a solvent that is not curable by actinic radiation, as opposed to one or more compounds present in the composition that are curable by actinic radiation. However, a non-reactive solvent may react with one or more components of the composition by other mechanisms.

[0123] For example, the curable composition can include less than 5 wt%, less than 2 wt%, less than 1 wt%, less than 0.5 wt%, less than 0.1 wt%, or even 0 wt% of a non-reactive solvent, based on the total weight of the composition.

[0124] In some embodiments, the curable composition may include a certain amount of one or more non-reactive solvents. For example, non-reactive solvents can be used to help dissolve one or more components of the composition and / or reduce the viscosity of the composition. The type of non-reactive solvent that can be used is not limited, provided that it does not interfere with the ability of the composition to be cured by exposure to actinic radiation. Suitable non-reactive solvents include, for example, ketones (such as acetone), esters, ethers, alcohols (including halogenated alcohols, such as fluorinated alcohols, aromatic hydrocarbons, etc.) and combinations thereof. Based on the gross weight of the composition, the composition that can be cured by actinic radiation can include at least 0.5 weight %, or at least 1 weight %, or at least 2 weight %, or at least 5 weight % of one or more non-reactive solvents. Alternatively, or additionally, based on the gross weight of the composition, the curable composition can include up to 90 weight %, or up to 80 weight %, or up to 70 weight %, or up to 60 weight %, or up to 50 weight %, or up to 40 weight %, or up to 30 weight %, or up to 25 weight %, or up to 20 weight % of one or more non-reactive solvents. For example, the curable composition may include 1 wt % to 50 wt % or 1 wt % to 25 wt % of the non-reactive solvent.

[0125] The non-reactive solvent may be a volatile non-reactive solvent or a non-volatile non-reactive solvent. As used herein, the term "volatile solvent" refers to a solvent having a boiling point less than or equal to 100° C. at atmospheric pressure, and the term "non-volatile solvent" refers to a solvent having a boiling point greater than 100° C. at atmospheric pressure. Combinations of volatile and non-volatile solvents may also be used.

[0126] In the context of the present invention, one or more non-reactive solvents may also be used when formulating the composition, in particular to help dissolve certain components, and then, after the components of the composition (including one or more non-reactive solvents) have been combined, at least a portion of the non-reactive solvents (up to all of the non-reactive solvents) may be removed to provide a final curable composition for use in the method according to the present invention. For example, the components of the composition may be combined, followed by mixing and / or heating to obtain a product or homogeneous solution, followed by removal of at least a portion of the non-reactive solvent by appropriate means such as distillation or vacuum stripping.

[0127] Other additives

[0128] Curable composition according to the present invention may include one or more other additives.Such additives may be, for example, selected from chain transfer agents, light blocking agents (light blocking agents), wetting agents (surface tension modifiers), matting agents, colorants, dyes, pigments, adhesion promoters, fillers, rheological agents / modifiers, flow control agents or leveling agents, thixotropic agents, plasticizers, light absorbers, light stabilizers, dispersants, antioxidants, antistatic agents, lubricants, sunscreens, defoamers, polymerization inhibitors and combinations thereof.In general, curable composition may include any additive conventionally used in the coating field.

[0129] The curable composition preferably comprises 2% by weight or less, more preferably 1% by weight or less, more preferably 0.5% by weight or less, more preferably 0.2% by weight or less of matting agent, and more preferably contains no matting agent. In the sense of the present invention, "matting agent" is any particle used to produce roughness at the surface of the coating, more particularly polymeric or inorganic particles, such as particles of silica, quartz, inorganic oxides, carbonates, nitrides, polyorganosiloxanes, elastomers or silsesquioxanes or urea-formaldehyde condensates, but does not include particles of the above-mentioned polyamides (which therefore do not belong to "matting agents" in the context of the present invention).

[0130] The curable composition of the present invention may include one or more light blocking agents (also referred to as absorbers). One or more light blocking agents may be any known material, including, for example, non-reactive pigments and non-reactive dyes. For example, a photoresist may be a reagent that blocks visible light or a reagent that blocks UV light. The example of a suitable light blocking agent includes titanium dioxide, carbon black and an organic ultraviolet light absorber, such as hydroxybenzophenone, hydroxyphenylbenzotriazole, oxalylanilide, benzophenone, thioxanthone, hydroxyphenyltriazine, Sudan Red I, bromothymol blue, 2,2'-(2,5-thiophene two bases) bis(5-tert-butylbenzoxazole) (particularly sold under the trade name Benetex® OB Plus) and benzotriazole type ultraviolet light absorbers. Based on the weight of the curable composition, the curable composition may contain a light blocking agent of an amount of 0.001% by weight to 10% by weight.

[0131] Preparation of curable compositions

[0132] The curable composition of the present invention can be prepared by any suitable method. For example, the various components can be combined and mixed in one or more steps. The components can be optionally heated, preferably after they have been combined and / or stirred, in particular to obtain a uniform composition. Other homogenization methods can also be used. In addition, as described above, one or more non-reactive solvents can be used. In some embodiments, during mixing, the polyamide particles are (preferably slowly) added to the other components of the composition at a temperature of 20° C. to 90° C.

[0133] Coating method

[0134] The curable composition as described above is used to form a coating on a surface.

[0135] The coating method according to the invention comprises applying the curable composition as a layer to a surface.

[0136] The surface can be any type of surface. The surface can be, for example, the surface of a high surface energy substrate (e.g., a metal substrate) or a low surface energy substrate (e.g., a plastic substrate). The substrate bearing the surface can comprise or consist of one or more metals, paper, paperboard, glass, one or more thermoplastic polymers such as polyolefins, polycarbonates, acrylonitrile-butadiene-styrene (ABS) polymers and mixtures thereof, composite materials, wood, leather, or combinations thereof.

[0137] The curable composition can be applied to the surface in any known conventional manner. More specifically, the composition can be applied, for example, by spraying, knife coating, roller coating, coating rod, flow coating, drum coating, dipping or a combination thereof. Application can be carried out at room temperature (i.e., from 15°C to 30°C) or at a higher temperature, particularly at a temperature of 30°C to 60°C. In particular, if the curable composition is not liquid or too viscous at room temperature, it can be heated to a temperature that enables it to liquefy or reduce viscosity before it is applied, so that it can be applied. More specifically, the composition can be, for example, heated to about 50°C for spraying application, which requires the composition to have a very low viscosity.

[0138] The layer advantageously has a thickness of less than or equal to 100 μm (e.g., from 1 μm to 100 μm), preferably less than or equal to 50 μm (e.g., from 1 μm to 50 μm), more preferably less than or equal to 20 μm (e.g., from 1 μm to 20 μm, preferably from 3 μm to 20 μm, more preferably from 10 μm to 20 μm). In particular, the layer of the curable composition may have a thickness of 1 to 3 μm, or 3 to 5 μm, or 5 to 10 μm, or 10 to 15 μm, or 15 to 20 μm, or 20 to 25 μm, or 25 to 30 μm, or 30 to 40 μm, or 40 to 50 μm, or 50 to 60 μm, or 60 to 70 μm, or 70 to 80 μm, or 80 to 90 μm, or 90 to 100 μm.

[0139] The layer of the curable composition is subjected to a step of irradiating with a first radiation. The first radiation is preferably monochromatic or quasi-monochromatic radiation. The first radiation is very advantageously UV radiation, and may be VUV ("vacuum ultraviolet") radiation. The first radiation is preferably applied by a UV lamp, and more preferably by an excimer lamp. An excimer lamp (or laser) is a gas discharge lamp that emits monochromatic or quasi-monochromatic radiation. They typically have a synthetic quartz lamp body filled with xenon (e.g., for emitting at 172nm) or krypton with a chlorine donor (e.g., for emitting at 222nm).

[0140] The irradiation is preferably carried out under an inert gas, more preferably under dinitrogen and / or carbon dioxide, more preferably under dinitrogen. The residual oxygen content is preferably less than or equal to 1000 ppm, more preferably less than or equal to 500 ppm.

[0141] More preferably, the wavelength of the first radiation is 100 to 280 nm, preferably 150 to 250 nm, more preferably 150 to 200 nm, more preferably 168 to 180 nm, more preferably 172 to 175 nm, still more preferably 172 nm. For example, the first radiation may have a wavelength of 100 nm to 125 nm, or 125 nm to 150 nm, or 150 nm to 175 nm, or 175 nm to 200 nm, or 200 nm to 225 nm, or 225 nm to 250 nm, or 250 nm to 280 nm.

[0142] The above wavelengths enable surface curing of a layer of the composition, which means curing at a low thickness below its surface (typically at a thickness of about 1 μm or less, in particular at a thickness of about 0.5 μm) by, for example, free radical and / or cationic polymerization. Individual surface curing of the layer results in the formation of folds at the surface of the layer.

[0143] This results in a partially cured, and more particularly surface cured, composition. "Partially cured composition" generally means that further curing is possible (more particularly, curing deeper portions of the layer of the curable composition).

[0144] The composition is subjected to a step of irradiation with a second radiation. The second radiation may be UV radiation or visible light, and / or electron beam radiation.

[0145] According to a first variant, the second radiation is UV radiation or visible light. It may be polychromatic or monochromatic. The second radiation comprises at least one wavelength different from the wavelength of the first radiation, and more particularly comprises at least one wavelength longer than the wavelength of the first radiation. Very preferably, it has a wavelength spectrum in the range of 100-900 nm. Further preferably, the second radiation has a wavelength spectrum in the range of 180 nm to 500 nm. Alternatively or additionally, the second radiation may comprise UVA and / or UVB and / or UVC radiation, or may be UVA and / or UVB and / or UVC radiation.

[0146] The second radiation preferably comprises at least one wavelength above 280 nm, preferably in the range of [above 280 nm] to 900 nm, more preferably in the range of 285 to 900 nm, more preferably in the range of 300 to 500 nm (in these embodiments, the second radiation may also optionally comprise wavelengths outside the above ranges). In particular, the second radiation may comprise at least one wavelength of [above 280 nm] to 300 nm, or 300 to 320 nm, or 320 to 350 nm, or 350 to 380 nm, or 380 to 400 nm, or 400 to 420 nm, or 420 to 450 nm, or 450 to 480 nm, or 480 to 500 nm, or 500 to 550 nm, or 550 to 600 nm, or 600 to 700 nm, or 700 to 800 nm, or 800 to 900 nm.

[0147] The radiation may be applied by means of a mercury vapor lamp, more particularly a medium-pressure or high-pressure mercury vapor lamp, the mercury vapor optionally being doped with elements such as gallium and / or iron, or by means of a metal halide lamp, an electroluminescent diode (or LED, for "light emitting diode"), more particularly an LED emitting UV light, or a pulsed laser lamp (also called a flash lamp). The second radiation is preferably emitted by an undoped mercury vapor lamp, a doped mercury vapor lamp or an LED lamp, the latter preferably having a wavelength of 350 nm to 405 nm.

[0148] The radiation dose applied during irradiation is advantageously between 80 and 4000 mJ / cm 2 , preferably 80 to 2000 mJ / cm 2 , more preferably 80 to 600 mJ / cm 2 , for example 80 to 300 mJ / cm 2 , or 300 to 600 mJ / cm 2 , or 600 to 1000 mJ / cm 2 , or 1000 to 2000 mJ / cm 2 , or 2000 to 3000 mJ / cm 2 , or 3000 to 4000 mJ / cm 2 .

[0149] According to a second variant, the second radiation is an electron beam. The electron beam preferably has an energy of 70 to 300 keV, preferably 150 to 300 keV, for example 70 to 150 keV, or 150 to 200 keV, or 200 to 250 keV, or 250 to 300 keV. The irradiation dose is advantageously 10 to 100 kGy, preferably 20 to 50 kGy, for example 10 to 20 kGy, or 20 to 30 kGy, or 30 to 40 kGy, or 40 to 50 kGy, or 50 to 70 kGy, or 70 to 100 kGy. Any suitable electron beam emitter can be used, in particular a scanner or a curtain emitter.

[0150] The step of irradiating with the second radiation may optionally be carried out in the absence of oxygen, for example in an inert gas atmosphere, or in an oxygen-deficient atmosphere. In some embodiments, the irradiation may be carried out by covering the composition with a radiation transparent medium (e.g., a plastic film). In particular, when the second radiation is an electron beam, it is preferably applied under an inert gas.

[0151] Whether it occurs according to the first variant and / or according to the second variant, the irradiation allows the curing of the layer to continue by, for example, free radical and / or cationic polymerization. In particular, it allows the curing of the portion of the layer located below the portion that was cured during exposure to the first radiation. This layer is preferably cured over its entire thickness. A cured composition is then obtained. In the sense of the present invention, a "cured composition" refers to a composition whose degree of crosslinking after the step of irradiation with the second radiation is greater than the degree of crosslinking of the partially cured composition.

[0152] Once cured, the coating preferably has a thickness of less than or equal to 100 μm (e.g., 1 to 100 μm), preferably less than or equal to 50 μm (e.g., 1 to 50 μm), more preferably 10 to 20 μm. In particular, the cured layer may have a thickness of 1 to 5 μm, or 5 to 10 μm, or 10 to 15 μm, or 15 to 20 μm, or 20 to 25 μm, or 25 to 30 μm, or 30 to 40 μm, or 40 to 50 μm, or 50 to 60 μm, or 60 to 70 μm, or 70 to 80 μm, or 80 to 90 μm, or 90 to 100 μm.

[0153] The method according to the invention may comprise one or more further steps of curing the composition, more particularly by irradiation with actinic radiation. These supplementary steps may be carried out at any point in time in the method, in particular before irradiation with the first radiation, between irradiation with the first radiation and irradiation with the second radiation, and / or after irradiation with the second radiation. The radiation used in each of these supplementary steps may independently be of any known type.

[0154] In particular, the method according to the invention may comprise an irradiation step (referred to herein as a "pre-crosslinking step") prior to irradiation with the first radiation, the pre-crosslinking step being more preferably carried out using UV radiation, more particularly UVA radiation. Advantageously, radiation with a wavelength of 200-420 nm, more preferably 280-420 nm, is used for pre-crosslinking. In some embodiments, the wavelength of the pre-crosslinking radiation may be from 200 to 280 nm, or from 280 to 320 nm, or from 320 to 380 nm, or from 380 to 420 nm. The radiation dose applied is preferably from 25 to 120 mJ / cm 2 , more preferably 30 to 100 mJ / cm 2 The radiation may be emitted by any suitable source, in particular by LED lamps, low-, medium- or high-pressure mercury vapor lamps (optionally doped with other elements, such as gallium or iron), pulsed (or flash) lamps or halogen lamps.

[0155] The emission sources for the first radiation and the second radiation and possibly other radiation (e.g. pre-crosslinking radiation) can independently be stationary or mobile. When the source is stationary, the object whose surface is covered with the composition to be irradiated is preferably mobile so as to pass in front of the irradiation source, for example transported by means such as a conveyor belt. When the source is movable, the object containing the composition to be irradiated preferably remains immobile during the step of irradiation by the source.

[0156] The above process may be repeated one or more times.Thus, a further layer of curable composition may be applied to the layer of cured composition and then subjected to curing by irradiation with actinic radiation, more particularly according to the process as described above.

[0157] The coating advantageously has a specular gloss at 85° of less than or equal to 10 GU, preferably less than or equal to 8 GU. The specular gloss at 85° can be measured according to standard ISO 2813:2014.

[0158] According to another aspect, the present invention relates to a coating obtained or obtainable from a curable composition as described above, more particularly a coating obtained or obtainable by a process as described above.

[0159] According to another aspect, the present invention relates to an object comprising a surface covered with a coating, the coating being obtained or obtainable from a curable composition as described above. The present invention also relates to an object comprising a surface covered with a coating, the coating being obtained or obtainable by a method as described above.

[0160] The object may be, for example, a decorative panel, a garment (in particular made of artificial leather) or a floor covering.

[0161] According to another aspect, the present invention relates to the use of an excimer lamp for at least partially curing (or cross-linking) a curable composition comprising at least one compound curable by actinic radiation and particles of at least one polyamide. The excimer lamp advantageously has a wavelength of 150 to 250 nm, preferably 150 to 200 nm, more preferably 168 to 180 nm, more preferably 172 to 175 nm. The curable composition is preferably layered. The above description of curable compositions, polyamides, layers of curable compositions and excimer lamps and their use may be similarly applicable to this aspect of the present invention.

[0162] Example

[0163] The following examples illustrate the present invention without limiting it.

[0164] Preparation of curable compositions

[0165] The following curable compositions were prepared containing the components in the amounts (expressed as mass percent) specified in the table below.

[0166] [Table 1]

[0167]

[0168] Composition A is a comparative curable composition; compositions 1, 2 and 3 are curable compositions according to the present invention.

[0169] The composition was prepared in the following manner:

[0170] - Preparation of a predispersion of polyamide 12 powder (= premix B)

[0171] 5 g of polyamide 12 powder are introduced into a mixture of 47.5 g of acrylate-functionalized epoxy oligomer (CN2003EU from Sartomer) and 47.5 g of 1,6-hexanediol diacrylate (SR238 from Sartomer) with the aid of a disperser equipped with a turbine under stirring at 1000 rpm. The polyamide 12 powder is introduced in small portions over about a quarter of an hour to allow the powder to be properly dispersed. When the introduction is complete, the mixture is left under stirring for another quarter of an hour. The preparation of a premix of PA 12 powder in the product CN2003EU enables efficient dispersion of the polyamide 12 powder during the preparation of the final composition.

[0172] - Preparation of the composition:

[0173] - Composition A (comparative):

[0174] 195.10 g of acrylate functionalized epoxy oligomer (CN2003EU from Sartomer) were diluted in 195.10 g of 1,6-hexanediol diacrylate (SR238 from Sartomer) using the same disperser under stirring. The following were then introduced in this order under stirring: 2.00 g of phosphine oxide photoinitiator (Speedcure® TPO-L from Lambson) and 7.80 g of hydroxyacetophenone photoinitiator (Speedcure® 84 from Lambson). The preparation was left under stirring for another quarter of an hour.

[0175] - Composition 1:

[0176] 35.10 g of acrylate functionalized epoxy oligomer (CN2003EU from Sartomer) were diluted in 35.10 g of 1,6-hexanediol diacrylate (SR238 from Sartomer) using the same disperser under stirring. The following were then introduced in this order under stirring: 28.10 g of premix B, then 0.40 g of phosphine oxide photoinitiator (Speedcure® TPO-L from Lambson) and 1.40 g of hydroxyacetophenone photoinitiator (Speedcure® 84 from Lambson). The preparation was left under stirring for another quarter of an hour.

[0177] - Composition 2:

[0178] 35.10 g of acrylate functionalized epoxy oligomer (CN2003EU from Sartomer) were diluted in 35.10 g of 1,6-hexanediol diacrylate (SR238 from Sartomer) using the same disperser under stirring. The following were then introduced in this order under stirring: 14.05 g of premix B, then 0.40 g of phosphine oxide photoinitiator (Speedcure® TPO-L from Lambson) and 1.40 g of hydroxyacetophenone photoinitiator (Speedcure® 84 from Lambson). The preparation was left under stirring for another quarter of an hour.

[0179] - Composition 3:

[0180] 35.10 g of acrylate functionalized epoxy oligomer (CN2003EU from Sartomer) were diluted in 35.10 g of 1,6-hexanediol diacrylate (SR238 from Sartomer) using the same disperser under stirring. The following were then introduced in this order under stirring: 7.025 g of premix B, then 0.40 g of phosphine oxide photoinitiator (Speedcure® TPO-L from Lambson) and 1.40 g of hydroxyacetophenone photoinitiator (Speedcure® 84 from Lambson). The preparation was left under stirring for another quarter of an hour.

[0181] Preparation of coating

[0182] A coating layer having a thickness of 12 μm was formed on a polyethylene terephthalate (PET) film from each of the above curable compositions.

[0183] To achieve this, the curable composition was applied to a rigid support plate of PET using a 12 μm application bar. These compositions were then crosslinked according to the following protocol: the films coated with the curable composition were arranged on a conveyor belt, allowing them to pass successively under a UV LED lamp (for pre-crosslinking), an excimer lamp and finally another UV lamp. The operating parameters were as follows:

[0184] -Belt speed: 10m / s.

[0185] - Crosslinking with a Xeradex® excimer lamp at 5 W / cm2 and 172 nm, with power set to 50%.

[0186] - UV crosslinking with an IST I-400-U-3-80 mercury vapor lamp at a maximum power of 200 W / cm2, power adjusted at 70% (corresponding to 750 mW / cm2 2 dose) and emits in UVA, UVB and UVC.

[0187] Tests performed:

[0188] The coatings obtained as described above were subjected to the following tests:

[0189] -Appearance of coating: The coatings were observed by optical microscopy and scanning electron microscopy.

[0190] - The number of defects was counted in a 8 cm x 8 cm square on the image obtained by optical microscopy.

[0191] - Specular gloss at 85°: measured using a gloss meter according to standard ISO 2813:2014.

[0192] - Polishing resistance: Polishing resistance is estimated as the increase in gloss measured according to standard ISO 2813:2014 after the coating has been rubbed (150 back and forth strokes) according to standard ISO 11640:2018 with a standardized white wool felt to which a weight of 3.5 kg is applied. The smaller the increase in gloss of the coating that has been subjected to rubbing, the better the polishing resistance.

[0193] - Chemical resistance: Chemical resistance is evaluated by rubbing (back and forth strokes) a cotton ball (1.5 cm x 1.5 cm x 0.5 cm) saturated with methyl ethyl ketone on the coating surface under a weight of 1 kg. The back and forth strokes are performed and counted until the coating breaks or detaches from the substrate. The higher the number of cycles before this occurs, the better the chemical resistance.

[0194] - Stain resistance: This property is determined by the color change (ΔE) of the coating after exposure to black iron oxide dust. The initial color of the coating is measured according to standard ISO 18314 on an Insitec spectrophotometer from Malvern with the aid of their coordinates L 、a , b 33% black iron oxide contamination solution in water is applied to the coating surface with the aid of a soft brush. The solution is left in contact with the coating for 3 hours at 23°C, then for 1 hour at 60°C and finally dried at 23°C for 20 hours. Excess contamination solution is removed with the aid of a soft brush and then the coating is dried according to standard ISO 18314 with the aid of its coordinates L 、a , b The color of the coating is measured and compared to the color of the uncontaminated coating. The color difference is calculated by ΔE according to the following formula express , where ΔL, Δa and Δb are the coordinates L between the contaminated coating and the uncontaminated coating according to ISO 18314. 、a and b The difference in ΔE The lower it is, the better the stain resistance of the coating.

[0195] result

[0196] The results are shown in the following table:

[0197] [Table 2]

[0198]

[0199] Micrographs of the coating formed from composition A and the coating formed from composition 3 obtained by scanning electron microscopy show that Figure 1 and Figure 2 middle.

[0200] It was found that the coating obtained from the curable composition comprising polyamide particles had a homogeneous appearance with hardly any defects present, whereas the coating obtained from composition A (without polyamide particles) showed many defects, which were folds oriented in a fan-shaped manner.

[0201] Furthermore, relative to the coating obtained from Comparative Composition A, the coating obtained from the curable composition according to the invention is more matte (ie, has a lower gloss) and exhibits greater polish resistance, greater chemical resistance and greater stain resistance.

[0202] Two comparative examples (4 and 5) were prepared in the same manner as composition 1, except that 1.4% of silica was added instead of 1.4% of polyamide 12 powder.

[0203] [Table 3]

[0204]

[0205] [Table 4]

[0206]

[0207] It was found that the coatings obtained from the composition comprising silica particles exhibited numerous defects which were folds oriented in a fan-shaped manner and were therefore less resistant to contamination due to the presence of attachment points (defects).

Claims

1. A method for coating a surface, comprising the steps of: - applying a layer of a curable composition to said surface; - irradiating the curable composition with a first radiation having a wavelength of 100 to 280 nm to obtain a partially cured composition; and - irradiating the partially cured composition with a second radiation comprising at least one radiation having a longer wavelength than the first radiation and / or an electron beam to obtain a cured composition; The curable composition comprises particles of at least one compound curable by actinic radiation and at least one polyamide.

2. The process according to claim 1, wherein the curable composition comprises from 0.01% to 2% by weight, preferably from 0.01% to 1.5% by weight, of particles of at least one polyamide, relative to the total weight of the composition. 3 . The process according to claim 1 , wherein the particles of at least one polyamide have a volume median diameter Dv50 less than or equal to 20 μm, preferably between 1 μm and 20 μm.

4. The method according to any one of claims 1 to 3, wherein the polyamide is selected from the group consisting of polyamide 12, polyamide 11, polyamide 10, polyamide 6, polyamide 6.10, polyamide 6.12, polyamide 6.6, polyamide 10.10, polyamide 10.12 and combinations thereof.

5. The method according to any one of claims 1 to 4, wherein the at least one compound curable by actinic radiation is an ethylenically unsaturated compound, preferably a compound comprising at least one group selected from acrylates, methacrylates, cyanoacrylates, acrylamides, methacrylamides, styrenes, maleates, fumarates, itaconates, allyls, propenyls, vinyls, methylenemalonates and combinations thereof, more preferably a compound comprising at least one functional group selected from acrylates, methacrylates and vinyls, still more preferably a compound comprising at least one functional group selected from acrylates and methacrylates.

6. The method according to any one of claims 1 to 5, wherein the curable composition comprises at least one photoinitiator, preferably selected from benzoin, benzoin ethers, acetophenones, benzil, benzil ketals, anthraquinones, phosphine oxides, α-hydroxyketones, phenylglyoxylic esters, α-aminoketones, benzophenones, thioxanthones, xanthones, acridine derivatives, phenazine derivatives, quinoxaline derivatives, triazine derivatives and combinations thereof.

7. The method according to any one of claims 1 to 6, wherein the first radiation has a wavelength of 150 to 250 nm, preferably 150 to 200 nm, more preferably 168 to 180 nm, more preferably 172 to 175 nm.

8. The method according to any one of claims 1 to 7, wherein irradiating the curable composition with the first radiation is performed using an excimer lamp.

9. The method according to any one of claims 1 to 8, wherein the second radiation has a wavelength spectrum in the range of 100 nm to 900 nm, preferably 180 nm to 500 nm.

10. The method according to any one of claims 1 to 9, wherein the second radiation comprises at least one wavelength in the range of 285 to 900 nm, preferably in the range of 300 to 500 nm.

11. The method according to any one of claims 1 to 10, wherein the second radiation is emitted by an undoped mercury vapor lamp, a doped mercury vapor lamp or an LED lamp, preferably with a wavelength in the range of 350 to 405 nm.

12. The method according to any one of claims 1 to 11, wherein the layer of curable composition applied to the surface has a thickness less than or equal to 100 μm, preferably less than or equal to 50 μm, more preferably less than or equal to 20 μm.

13. A coating obtained by the method according to any one of claims 1 to 12.

14. An object comprising a surface covered with a coating according to claim 13.

15. A composition comprising at least one compound curable by actinic radiation and 0.01% to 2% by weight, preferably 0.01% to 1.5% by weight, relative to the total weight of the composition, of particles of at least one polyamide.

16. A coating based on the composition according to claim 15.

17. Use of an excimer lamp for at least partially curing a composition according to claim 15 or 16.

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