Acrylic copolymer imparting low yellowing after photocuring

Abstract

Provided is an acrylic copolymer comprising polymerized high Tg monomer units and / or polymerized low Tg monomer units; a polymerized chromophore monomer unit comprising a chromophore moiety selected from the group consisting of thioxanthone, anthraquinone or camphorquinone; and optionally polymerized additional monomer units. Also provided are cured compositions that are the product of photocuring a composition comprising an acrylic copolymer, where the cured compositions exhibit low yellowing. Also provided is a method of coating a substrate comprising applying a composition comprising an acrylic copolymer to a substrate and exposing a coating to UV radiation to cure the composition.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to acrylic copolymers, and more particularly, to acrylic copolymers containing a pendent photoinitiator that impart low yellowing after photocuring. Background Art

[0002] Radiation curable compositions are used in a variety of different applications, from industrial coatings and graphics to UV-curable nail polish and 3D printing. Small molecule photoinitiators are key ingredients in such compositions as they are able to promote polymerization when exposed to a suitable light source.

[0003] The selection of a small molecule photoinitiator in a radiation curable composition affects the light source required to initiate polymerization and the properties of the photocured polymer. For example, small molecule photoinitiators that promote polymerization when exposed to short wavelength light tend to not yellow and provide good surface cure and poor depth of cure. In contrast, small molecule photoinitiators that promote polymerization when exposed to long wavelength light tend to provide high yellowing and good depth of cure, but poor surface cure, which can result in a tacky surface.

[0004] Small molecule photoinitiators can be further classified as Norrish Type I or Norrish Type II. Norrish Type I photoinitiators split when exposed to a suitable light source to form two free radical species that induce crosslinking. Norrish Type II photoinitiators generate an excited state when exposed to a suitable light source and abstract hydrogen from a co-initiator, which generates free radicals to induce crosslinking.

[0005] Commonly used Norrish II type photoinitiators include benzophenone, thioxanthone, camphorquinone and anthraquinone. These photoinitiators are typically used in pairs with co-initiators such as amines, alcohols and ethers. Tertiary amines are most commonly used as co-initiators due to their high reactivity to Norrish II type photoinitiators in their excited state.

[0006] Norrish Type II photoinitiators (i.e., thioxanthones) having absorption bands at longer wavelengths may be particularly effective photoinitiators for certain applications. In particular, additives in some radiation curable compositions may absorb shorter wavelength light and thereby inhibit photoinitiators that absorb similar wavelength light from properly initiating polymerization, which may result in improper curing. Since additives may not absorb longer wavelength light, their inhibitory effect may be reduced when using Norrish Type II photoinitiators (i.e., thioxanthones) having absorption bands at longer wavelengths. Summary of the invention

[0007] Although thioxanthone and other Norrish II type photoinitiators with absorption bands at longer wavelengths have utility, they are not without disadvantages. In particular, they tend to impart yellowing to crosslinked polymers and do not photobleach over time. Further, they may be difficult to remove from crosslinked polymers and may instead remain within the polymer matrix and slowly diffuse to the surface over time. Such photoinitiator migration may be detrimental, depending on the application. Therefore, there is a need for Norrish II type photoinitiators with absorption bands at longer wavelengths that provide low initial yellowing to crosslinked polymers and exhibit little to no migration after curing.

[0008] Embodiments of the acrylic copolymers disclosed herein meet this need by incorporating a Norrish II-type photoinitiator having an absorption band at a longer wavelength attached to the oligomer backbone. When the acrylic copolymer is mixed with at least one (meth)acrylate monomer and the resulting composition is photocured, the resulting polymer can exhibit low yellowing. Further, since the acrylic copolymer becomes incorporated into the polymer backbone upon photocuring, the photoinitiator moiety can exhibit little or no migration.

[0009] In one or more embodiments, an acrylic copolymer is provided. The acrylic copolymer comprises the reaction product of: (1) having a glass transition temperature (T) equal to or greater than 25°C; g ) g Monomer, with a T less than 25°C g Low T g Monomer, or having a glass transition temperature (T) equal to or greater than 25°C g ) g monomer and having a T less than 25°C g Low T g The invention relates to a combination of monomers, (2) a chromophore monomer comprising a moiety selected from thioxanthone, anthraquinone or camphorquinone, and (3) optionally at least one additional monomer.

[0010] In some embodiments, a curable composition is provided, wherein the curable composition comprises the acrylic copolymer of the present invention and a reactive diluent.

[0011] In some embodiments, a method for preparing a curable composition is provided. The method comprises the following steps:

[0012] - preparing an acrylic copolymer according to the invention dissolved in a non-reactive solvent;

[0013] - adding a reactive diluent to obtain a diluted curable composition;

[0014] - removing at least part of the non-reactive solvent from the diluted curable composition to obtain a curable composition.

[0015] In some embodiments, a method of curing a curable composition is provided. The method includes curing the curable composition by irradiating the curable composition with a light source having a wavelength and / or intensity capable of activating polymerized chromophore monomer units of an acrylic copolymer and causing crosslinking of the acrylic copolymer and / or the reactive diluent.

[0016] In some embodiments, a cured composition is provided. The cured composition is the product of photocuring a composition comprising an acrylic copolymer and a reactive diluent, preferably at least one (meth)acrylate monomer. The cured composition exhibits an APHA-10 mm initial color of 0.1 to 50; an initial yellowness (b ); and a T equal to or greater than 0°C g .

[0017] In one or more embodiments, a method of coating a substrate is provided. The method comprises applying a composition to a substrate to form an uncured coating of the composition on the substrate. The composition comprises an acrylic copolymer and a reactive diluent, preferably at least one (meth)acrylate monomer. The method further comprises exposing the uncured coating to UV radiation to cure the composition and obtain a cured coating on the substrate.

[0018] Additional features and advantages of the embodiments will be set forth in the detailed description which follows, and in part will be apparent to those skilled in the art from the description or may be learned by practicing the embodiments, including the following detailed description, claims, and drawings. DETAILED DESCRIPTION

[0019] definition

[0020] As used herein, the term "comprising" may mean "including one or more".

[0021] Unless otherwise stated, weight percentages in compounds or compositions are expressed relative to the weight of the compound, respectively composition.

[0022] The term "substituted" as used herein means that at least one hydrogen atom (-H) bonded to a carbon atom or heteroatom of a corresponding unsubstituted compound or functional group is replaced by a substituent (e.g., R S The term "full substitution" means that each hydrogen atom (-H) bonded to a carbon atom or heteroatom of the corresponding unsubstituted compound or functional group is replaced by a substituent (e.g., R SThe term "polysubstituted" means that at least two but less than all hydrogen atoms bonded to carbon atoms or heteroatoms of the corresponding unsubstituted compound or functional group are replaced by substituents. Unless otherwise defined or limited in a particular context, substituents are generally referred to as R S The substituents of can be any chemical moiety, typically but not necessarily limited to chemical moieties having 1 to 50, or 1 to 40, or 1 to 30, or 1 to 20, or 1 to 10 total atoms. The substituent R S Examples of include, but are not limited to, hydrocarbon, heterohydrocarbon, aryl, heteroaryl, alkyl, cycloalkyl, heteroatom, carbonyl, hydroxyl, ester, amine, amide, or halide, as defined herein or as generally understood, wherein any substituent itself may be substituted or unsubstituted. In some embodiments, the substituent R S Can be selected from (C1-C 30 ) hydrocarbon group, (C1-C 30 ) heteroalkyl, (C6-C 30 )aryl or (C6-C 30 ) heteroaryl.

[0023] The term "hydrocarbyl" refers to a monovalent hydrocarbon, wherein each hydrocarbon is aromatic or non-aromatic, saturated or unsaturated, straight chain or branched, cyclic (having three or more carbons, and including monocyclic and polycyclic, fused and non-fused polycyclic and bicyclic) or acyclic, and is substituted by one or more R S In the present disclosure, the hydrocarbon group may be an unsubstituted or substituted alkyl group, an unsubstituted or substituted cycloalkyl group, or an unsubstituted or substituted aryl group. The hydrocarbon group may not contain any heteroatoms selected from O, N or S. 30 ) The hydrocarbon group is a hydrocarbon group having 1 to 30 carbon atoms.

[0024] The term "heteroalkyl" refers to an alkyl group with one or more heteroatoms independently selected from O, N or S. 30 ) The heteroalkyl group is a heteroalkyl group having 1 to 30 carbon atoms.

[0025] The term "aryl" refers to an optionally substituted polyunsaturated aromatic group. The aryl group may contain a single ring (i.e., phenyl) or more than one ring, wherein at least one ring is aromatic. When the aryl group contains more than one ring, the rings may be fused, connected by covalent bonds (e.g., biphenyl). The aromatic ring may optionally contain one to two additional fused rings (i.e., cycloalkyl, heterocycloalkyl, or heteroaryl). Examples include phenyl, naphthyl, biphenyl, phenanthryl, and benzanthryl (naphthacenyl).

[0026] The term "alkyl" refers to a group of the formula -C n H 2n+1A monovalent saturated non-cyclic hydrocarbon radical of alkyl, wherein n is 1 to 20. The alkyl group may be linear or branched. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, 2-methylbutyl, 2,2-dimethylpropyl, n-hexyl, 2-methylpentyl, 2,2-dimethylbutyl, n-heptyl, 2-ethylhexyl, and the like.

[0027] The term "cycloalkyl" refers to a monovalent saturated alicyclic hydrocarbon group containing a ring. Examples of cycloalkyl groups include cyclopentyl, cyclohexyl and isobornyl, any of which may be substituted or unsubstituted.

[0028] The term "heterocycloalkyl" refers to a cycloalkyl group having at least one ring atom as a heteroatom selected from O, N or S.

[0029] The term "halogen" refers to an atom selected from Cl, Br, F and I.

[0030] The term "alkoxy" refers to a group of the formula -O-alkyl, wherein alkyl is as defined above.

[0031] The term "aryloxy" refers to a group of the formula -O-aryl wherein aryl is as defined above.

[0032] The term "thioalkyl" refers to a group of the formula -S-alkyl, wherein alkyl is as defined above.

[0033] The term "thioaryl" refers to a group of the formula -S-aryl wherein aryl is as defined above.

[0034] The term "alkenyl" refers to a monovalent non-cyclic hydrocarbon group containing at least one C=C double bond. The alkenyl group may be straight-chain or branched.

[0035] The term "alkynyl" refers to a monovalent non-cyclic hydrocarbon group containing at least one C≡C triple bond. Alkynyl groups may be straight-chain or branched.

[0036] The term "aralkyl" refers to an aryl group substituted with an alkyl group. An example of an aralkyl group is tolyl.

[0037] The term "alkaryl" refers to an alkyl group substituted with an aryl group. An example of an alkaryl group is benzyl (-CH2-phenyl).

[0038] The term "heteroaryl" refers to an aryl group having at least one ring atom which is a heteroatom.

[0039] The term "alkylamino" refers to an alkyl group substituted with at least one amino group.

[0040] The term "alkylthiol" refers to an alkyl group substituted with at least one thiol group.

[0041] The term "hydroxyalkyl" refers to an alkyl group substituted with at least one hydroxy group.

[0042] The term "haloalkyl" refers to an alkyl group substituted with at least one halogen.

[0043] The term "alkylene" or "alkanediyl" refers to a linker derived from a group consisting of m H 2m+2 The alkane of the linker is prepared by removing one hydrogen atom at each point of attachment of the linker. The alkylene group can be divalent, trivalent, tetravalent or have an even higher valence.

[0044] The term "alkoxylated" refers to compounds, groups or linkers that contain one or more oxyalkylene moieties, in particular one or more oxyalkylene moieties selected from oxyethylene (-O-CH2-CH2-), oxypropylene (-O-CH2-CH(CH3)- or -O-CH(CH3)-CH2-), oxybutylene (-O-CH2-CH2-CH2-CH2-) and mixtures thereof. For example, the alkoxylated compound, group or linker may contain 1 to 30 oxyalkylene moieties.

[0045] The term "(meth)acrylate" refers to acrylate or methacrylate. The term "acrylate" refers to an acryloyloxy group (-OC(=O)-CH=CH2). The term "methacrylate" refers to a methacryloyloxy group (-OC(=O)-C(CH3)=CH2).

[0046] The term (meth)acrylate monomer refers to a monomer carrying a (meth)acrylate group.

[0047] As used herein, the "monomer" has a number average molecular weight of less than 1,000 g / mol, preferably 100 to 950 g / mol.

[0048] As used herein, the "oligomer" has a number average molecular weight equal to or greater than 1,000 g / mol, preferably 1,050 to 60,000 g / mol, more preferably 10,000 to 50,000 g / mol.

[0049] The term "glass transition temperature" or "T g ” refers to the temperature at which a material transitions from a glassy state to a rubbery state. In this case, the term “glassy” means that the material is hard and brittle, while the term “rubbery” means that the material is elastic and flexible. For polymeric materials, T g is the critical temperature that distinguishes its glass and rubber behavior. g At temperatures below 100 °C, large-scale molecular motion is severely restricted because the material is essentially frozen. On the other hand, if a polymer-based material is heated above its T gAt temperatures below 300 °C, molecular motion on the scale of its repeating unit occurs, allowing it to be soft or rubbery.

[0050] The monomer T referred to in this article is g Both refer to the T of the homopolymer formed by the monomer g . Common monomer T g The values ​​are well known in the literature. If not reported in the literature, the glass transition temperature value can be determined as the inflection temperature (T i The glass transition temperatures of the acrylic copolymers described herein and in the examples below are calculated using the Fox equation based on the mass fraction of each individual monomer in a polymeric material or oligomer containing more than one discrete monomer type and T g Value calculated.

[0051] The terms "mass fraction" and "weight fraction" are used interchangeably herein and should be considered equivalent for purposes of the examples or embodiments herein.

[0052] The “Fox equation” refers to equation (1):

[0053] 1 / T g,mix ≈ ∑ i ω i / T g,i Equation (1)

[0054] Among them, T g,mix is the glass transition temperature of a mixture of i chemically unrelated components (such as two or more different monomers of an oligomer or polymer), T g,i is the glass transition temperature of the ith component, and ω i is the mass fraction of the ith component based on the total mass of the oligomer or polymer. Hereinafter, the value T for multiple unrelated monomers in the oligomer or polymer is g,mix The Fox equation average T of multiple unrelated monomers is called g ”.

[0055] For two components A and B, the Fox equation simplifies to equation (2):

[0056] 1 / T g,mix ≈ ω A / T g,A+ ω B / T g,B Equation (2)

[0057] The term "high T g "Monomer unit" means a monomer unit which, when homopolymerized, produces a monomer having a T of equal to or greater than 25°C. g In the following oligomer embodiment: only one high T g The monomer units are present in oligomers, and the high T g T of monomer unit g Is this a high T g T of the homopolymer of the monomer unit g In an embodiment of the oligomers wherein two or more types of different high T g The monomer units exist in oligomers, and the high T g T of monomer unit g Commonly referred to as high T g Fox equation average T of monomer unit combination g , where for equation (1), the individual mass fraction ω i is the individual high T in the oligomer g The mass fraction of monomer units based on all high T present in the oligomer g Monomer units (i.e., having a T equal to or greater than 25°C) g The total mass of the monomer units) is used as the basis for the calculation, rather than the total mass of the entire oligomer.

[0058] The term "Fox equation average (value)" may be used herein even for a single monomer that is not part of a mixture of two or more monomers. It should be readily understood that the Fox equation average T for a single monomer is g Equal to the T of a single monomer g (as defined herein), since in such case the term mass fraction term ω is equal to 1.

[0059] The term "low T g "Monomer unit" means a monomer unit which, when homopolymerized, produces a monomer having a T of less than 25°C. g In the following oligomer embodiment: only one low T g The monomer units are present in oligomers, the low T g T of monomer unit g Is this a low T g T of the homopolymer of the monomer unit g In an embodiment of the oligomers wherein two or more types of different low T g The monomer units exist in oligomers, and the low T g T of monomer unitg Commonly referred to as low T g Fox equation average T of monomer unit combination g , where for equation (1), the individual mass fraction ω i It is the individual low T in the oligomer g The mass fraction of the monomer unit, based on all low T g Monomeric units (i.e., having a T of less than 25°C) g The total mass of the monomer units) is used as the basis for the calculation, rather than the total mass of the entire oligomer.

[0060] The term "photoinitiator" may be considered to be any type of substance which, when exposed to radiation (eg, actinic radiation), forms a substance that initiates reaction and curing of polymeric organic materials present in the curable composition.

[0061] The term "chromophore" as used herein refers to a Norrish type II light absorbing molecule that enters an excited state upon absorption of light. From this excited state, the molecule can interact or react with other molecules to produce reactive radical species.

[0062] The term "independently selected from" is used herein to refer to substituents such as Z 1 , Z 2 , Z 3 and Z 4 , which may be the same or different (e.g., Z 1 , Z 2 , Z 3 and Z 4 All can be -CH3; or Z 1 and Z 2 Can be -CH3 and Z 3 and Z 4 The chemical names associated with substituents are intended to convey chemical structures that are recognized in the art to correspond to the chemical structures of the chemical names. Therefore, the chemical names are intended to supplement and illustrate, rather than exclude, structural definitions known to those skilled in the art.

[0063] When used to describe certain chemical groups containing carbon atoms, the group having the form "(C x -C y )" means that the unsubstituted form of the chemical group has from x to y carbon atoms, including x and y. For example, (C1-C 20 ) Hydrocarbyl is a hydrocarbon group having 1 to 20 carbon atoms in unsubstituted form. In some embodiments and general structures, certain chemical groups may be substituted by one or more substituents such as R S Replace. Use "(C x -C y)" brackets define the chemical group R S The substituted version may contain more than y carbon atoms, depending on any group R S For example, "is exactly one group R S Substituted (C1-C 20 ) alkyl, wherein R S is phenyl (-C6H5)" may contain 7 to 27 carbon atoms. Therefore, generally when brackets "(C x -C y )" is replaced by one or more carbon-containing substituents R S When substituted, the minimum and maximum total number of carbon atoms in the chemical group is determined by adding all the substituents R containing carbon atoms. S The number of carbon atoms is determined by the combined sum of both x and y.

[0064] The term "-H" refers to a hydrogen atom covalently bonded to an atom other than hydrogen. "Hydrogen" and "-H" are interchangeable and have the same meaning unless expressly stated otherwise.

[0065] The term "(C1-C 30 )hydrocarbyl refers to a monovalent hydrocarbon of 1 to 30 carbon atoms, wherein each monovalent hydrocarbon is aromatic or non-aromatic, saturated or unsaturated, straight chain or branched, cyclic (having three or more carbon atoms, and including monocyclic and polycyclic, fused and non-fused polycyclic and bicyclic) or acyclic, and is substituted by one or more R S In the present disclosure, (C1-C 30 The hydrocarbon group may be unsubstituted or substituted (C1-C 30 )alkyl, (C3-C 30 )cycloalkyl or (C6-C 30 )aryl.

[0066] The term "(C2-C 30 )alkyl" refers to an alkyl group which is unsubstituted or substituted with one or more R S Substituted saturated straight or branched monovalent hydrocarbons of 2 to 30 carbon atoms. 30 Examples of alkyl groups are unsubstituted (C2-C 20 ) alkyl; unsubstituted (C6-C 25 )alkyl; unsubstituted (C4-C8)alkyl; 1-butyl; 2-butyl; 2-methylpropyl; 1,1-dimethylethyl; 1-pentyl; 1-hexyl; 1-heptyl; 1-nonyl; and 1-decyl. Substituted (C2-C 30 Examples of alkyl groups are substituted (C2-C 20 ) alkyl, substituted (C2-C 10 )alkyl.

[0067] The term "(C6-C 40 ) aryl" refers to an unsubstituted or (substituted by one or more R S ) substituted monocyclic, bicyclic or tricyclic aromatic monovalent hydrocarbons of 6 to 40 carbon atoms, wherein at least 6 to 14 carbon atoms are aromatic ring carbon atoms. Monocyclic aromatic monovalent hydrocarbons include one aromatic ring; bicyclic aromatic monovalent hydrocarbons have two rings; and tricyclic aromatic monovalent hydrocarbons have three rings. When bicyclic or tricyclic aromatic monovalent hydrocarbons are present, at least one ring of the monovalent hydrocarbon is aromatic. The other one or more rings of the aromatic monovalent hydrocarbon may independently be fused or non-fused and be aromatic or non-aromatic. Unsubstituted (C6-C 40 Examples of aryl groups include: unsubstituted (C6-C 20 ) aryl, unsubstituted (C6-C 18 )aryl; 2-(C1-C5)alkyl-phenyl; phenyl; fluorenyl; tetrahydrofluorenyl; indanyl; tetrahydroindanyl; tetrahydroindanyl; indenyl; dihydroindenyl; naphthyl; tetrahydronaphthyl; and phenanthrene. Substituted (C6-C 40 Examples of aryl groups include: substituted (C1-C 20 ) aryl; and substituted (C6-C 18 )aryl.

[0068] The term "(C6-C 12 ") cycloalkyl" refers to an unsubstituted or substituted saturated cyclic monovalent hydrocarbon of 6 to 12 carbon atoms. Other cycloalkyl groups (e.g., (C x -C y )cycloalkyl) is defined in a similar manner as having x to y carbon atoms and being unsubstituted or substituted by one or more R S Substituted. Unsubstituted (C6-C 12 Examples of cycloalkyl groups are unsubstituted (C6-C8)cycloalkyl, unsubstituted (C6-C 10 )cycloalkyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl and cyclodecyl. 12 Examples of cycloalkyl groups are substituted (C6-C8)cycloalkyl, substituted (C6-C 10 )cycloalkyl, isobornyl and 3,3,5-trimethylcyclohexyl.

[0069] The term "heteroatom" refers to an atom other than hydrogen or carbon. Examples of heteroatoms include O, S, N, Si. The term "heterohydrocarbon" refers to a molecule or molecular framework in which one or more carbon atoms of a hydrocarbon are replaced by a heteroatom. The term "(C1-C 30 )heteroalkyl" refers to a monovalent heteroalkyl of 1 to 30 carbon atoms, and the term "(C1-C 30 "Heteroalkylene" refers to a divalent heteroalkyl group of 1 to 30 carbon atoms. (C1-C30 )heteroalkyl or (C1-C 30 ) The heteroalkylene has one or more heteroatoms. The valence or point of attachment of the heteroalkylene may be on a carbon atom or a heteroatom. The two valences of the heteroalkylene may be on a single carbon atom or a single heteroatom. In addition, one of the two valences or points of attachment of the diradical (diradical) may be on a carbon atom and the other valence may be on a different carbon atom; one of the two valences or points of attachment may be on a carbon atom and the other may be on a heteroatom; or one of the two valences or points of attachment may be on a heteroatom and the other valence or point of attachment may be on a different heteroatom. Each (C1-C 30 ) heteroalkyl and (C1-C 30 The heteroalkylene group may be unsubstituted or substituted, aromatic or non-aromatic, saturated or unsaturated, linear or branched, cyclic (including monocyclic and polycyclic, fused and non-fused polycyclic) or acyclic.

[0070] The term "saturated" means lacking carbon-carbon double bonds, carbon-carbon triple bonds, and (in heteroatom-containing groups) carbon-nitrogen, carbon-phosphorus, and carbon-silicon double bonds. S When substituted, the substituent R S One or more double bonds and / or triple bonds may or may not be present. The term "unsaturated" means containing one or more carbon-carbon double bonds, carbon-carbon triple bonds or (in a group containing heteroatoms) one or more carbon-nitrogen, carbon-phosphorus or carbon-silicon double bonds, excluding the substituent R S Any double bonds present in the (hetero)aromatic ring (if any) or any double bonds present in the (hetero)aromatic ring (if any).

[0071] The term "linker" refers to a multivalent group. A linker can connect at least two parts of a compound together, in particular, connect 2 to 16 parts of a compound together. For example, a linker that connects two parts of a compound together is called a divalent linker, and a linker that connects three parts of a compound together is called a trivalent linker.

[0072] As used herein, "weight average molecular weight ('Mw')" is determined by size exclusion chromatography (SEC) using polymethyl methacrylate reference standards and tetrahydrofuran as solvent, unless specifically stated otherwise.

[0073] It is found that embodiments of the acrylic copolymers described herein include a Norrish II-type photoinitiator (i.e., thioxanthone, anthraquinone, or camphorquinone) having an absorption band at a longer wavelength mixed with at least one (meth)acrylate monomer, and the resulting composition is photocured, and the resulting polymer can exhibit low yellowing. Without being bound by theory, it is believed that the reason why compositions cured with small molecule Norrish II-type photoinitiators having an absorption band at a longer wavelength exhibit relatively high yellowing is that the small molecule photoinitiator reacts during curing to form dimers and other byproducts, which impart yellowing to the cured composition. It is believed that when the photoinitiator is covalently attached to an acrylic copolymer (such as an embodiment of the acrylic copolymer described herein), the chance of dimerization of the photoinitiator is significantly reduced. Further, since the embodiments of the acrylic copolymers described herein become incorporated into the polymer backbone upon photocuring, the photoinitiator portion can exhibit little or no migration.

[0074] Acrylic copolymer

[0075] The acrylic copolymers herein (also referred to as oligomers) include at least one polymerized chromophore monomer unit, as defined herein. The acrylic copolymers herein further include at least one polymerized monomer unit selected from polymerized high T g Monomer units, polymerized low-T g Monomer units or at least one polymerized high T g monomer units and at least one polymerized low-T g The acrylic copolymers herein optionally include at least one polymerized additional monomer unit, as defined herein. The acrylic copolymers may not contain polymerized monomer units other than polymerized high Tg monomer units, polymerized low Tg monomer units, polymerized chromophore monomer units, and optional polymerized additional monomer units. g Monomer unit, polymerized low T g The total weight of the monomer units, polymerized chromophore monomer units and polymerized additional monomer units may account for at least 97%, particularly at least 98%, more particularly at least 99%, still more particularly 100% of the total weight of the acrylic copolymer.

[0076] In an embodiment, the acrylic copolymer comprises 0 wt % to 99.9 wt % of a polymerized high T g Monomer units, 0 wt % to 99.9 wt % of polymerized low T gmonomer units, 0.1 wt % to 40 wt % of polymerized chromophore monomer units, and 0 to 20 wt % of polymerized additional monomer units, provided that the acrylic copolymer comprises at least 40 wt %, or at least 50 wt %, or at least 60 wt %, or at least 70 wt %, or at least 80 wt %, or at least 90 wt % of polymerized high T g Low T of monomer units and polymers g The combined total amount of monomer units.

[0077] In one or more embodiments, the acrylic copolymer comprises a glass transition temperature (T) equal to or greater than 25°C. g ) g The reaction product of a monomer, a chromophore monomer comprising a moiety selected from thioxanthone, anthraquinone or camphorquinone, and optionally at least one additional monomer. According to one or more embodiments, the chromophore monomer comprises a moiety comprising thioxanthone.

[0078] In one or more embodiments, the acrylic copolymer comprises a T of less than 25°C. g Low T g The reaction product of a monomer, a chromophore monomer comprising a moiety selected from thioxanthone, anthraquinone or camphorquinone, and optionally at least one additional monomer. According to one or more embodiments, the chromophore monomer comprises a moiety comprising thioxanthone.

[0079] In one or more embodiments, the acrylic copolymer comprises a glass transition temperature (T) equal to or greater than 25°C. g ) g Monomer, with a T less than 25°C g Low T g The reaction product of a monomer, a chromophore monomer comprising a moiety selected from thioxanthone, anthraquinone or camphorquinone, and optionally at least one additional monomer. According to one or more embodiments, the chromophore monomer comprises a moiety comprising thioxanthone.

[0080] In an embodiment, the acrylic copolymer has formula (I):

[0081] in:

[0082] - Each A 1 Independently (C1-C 30 )alkyl or (C1-C 30 ) heteroalkyl, preferably (C1-C 30 ) alkyl;

[0083] - Each A 2 Independently (C4-C 30 )alkyl or (C4-C 30) heteroalkyl, preferably (C4-C 30 ) alkyl;

[0084] - Each A 3 are independently a residue comprising a monovalent group comprising a moiety selected from thioxanthone, anthraquinone or camphorquinone, preferably thioxanthone.

[0085] - Each A 4 Independently (C1-C 30 )alkyl or (C1-C 30 ) heteroalkyl;

[0086] -Z 1 , Z 2 , Z 3 and Z 4 Independently -H or (C1-C4) alkyl, preferably -H or -CH3;

[0087] -m means high T g The weight fraction of the monomer is 0 to 0.999;

[0088] -n is low T g The weight fraction of the monomer is 0 to 0.999;

[0089] -p is the weight fraction of the chromophore monomer and is 0.001 to 0.4;

[0090] -q is the weight fraction of the additional monomer and is from 0 to 0.2;

[0091] -m+n is greater than or equal to 0.4; and

[0092] -m+n+p+q=1.

[0093] In an embodiment, m is from 0.001 to 0.999, preferably from 0.01 to 0.50; n is from 0.001 to 0.999, preferably from 0.50 to 0.98; and m+n is greater than or equal to 0.6.

[0094] High Tg monomer unit

[0095] The acrylic copolymers disclosed herein may include polymerized high T g Monomer unit. High T g The monomer unit is different from the low T g monomer units, chromophore monomer units and additional monomer units. Therefore, low T g The monomer unit may not contain any of the following groups:

[0096] - chromophore moiety;

[0097] - functional groups as defined below for the additional monomer units.

[0098] Polymerized high T g The monomer units may be the same or a combination of multiple types of unrelated monomer units such as two types of unrelated monomer units, three types of unrelated monomer units, four types of unrelated monomer units, or more than four types of unrelated monomer units. g The monomer unit has a glass transition temperature (T) equal to or greater than 25°C. g ) or Fox equation average T g As defined herein, the T of a monomer as referred to herein is g refers to the T of the homopolymer formed by the monomer g In the following embodiment: wherein the acrylic copolymer comprises two or more different high T g A combination of monomer units such as methyl (meth)acrylate and isobornyl (meth)acrylate, T g It refers to high T g Fox equation average T of monomer unit g , as defined above in this document. In an embodiment, the high T g Fox equation average T of monomer unit g The temperature of the high T is greater than 25°C, such as equal to or greater than 30°C, equal to or greater than 35°C, equal to or greater than 40°C, equal to or greater than 45°C, equal to or greater than 50°C, equal to or greater than 55°C, equal to or greater than 60°C, equal to or greater than 65°C, equal to or greater than 70°C, equal to or greater than 75°C, or even equal to or greater than 80°C. In an embodiment, the high T g The monomer units may have the following T g: 25°C to 200°C, 25°C to 150°C, 25°C to 130°C, 30°C to 200°C, 30°C to 150°C, 30°C to 130°C, 35°C to 200°C, 35°C to 150°C, 35°C to 130°C, 40°C to 200°C, 40°C to 150°C, 40°C to 130°C, 45°C to 200°C, 45°C to 150°C, 45°C to 130°C, 50°C to 200°C, 50°C to 150°C, 50°C to 13 C to 0°C, 55°C to 200°C, 55°C to 150°C, 55°C to 130°C, 60°C to 200°C, 60°C to 150°C, 60°C to 130°C, 65°C to 200°C, 65°C to 150°C, 65°C to 130°C, 70°C to 200°C, 70°C to 150°C, 70°C to 130°C, 75°C to 200°C, 75°C to 150°C, or even 75°C to 130°C, or any and all subranges formed by any of these endpoints.

[0099] If the acrylic copolymer includes a high T g Monomer and Low T g Both monomers (i.e., both m and n of formula (I) are not zero), then high T g Fox equation average T of monomer unit g Greater than low T g Fox equation average T of monomer unit g In an embodiment, high T g Fox equation average T of monomer unit g T g Fox equation average T of monomer unit g In an embodiment, the high T g Fox equation average T of monomer unit g With low T g Fox equation average T of monomer unit g The difference between the high T and the low T is greater than 20°C, such as greater than 25°C, greater than 30°C, greater than 35°C, greater than 40°C, greater than 45°C, greater than 50°C, greater than 55°C, greater than 60°C, greater than 65°C, greater than 70°C, greater than 75°C, greater than 80°C, greater than 85°C, greater than 90°C, greater than 95°C, greater than 100°C, greater than 105°C, greater than 110°C, greater than 115°C, or greater than 120°C. In an embodiment, the high T g Fox equation average T of monomer unit g and low T g Fox equation average T of monomer unitg The difference between is 20°C to 200°C. As a non-limiting example, high T g Fox equation average T of monomer unit g and low T g Fox equation average T of monomer unit g The difference between the above values ​​may be 20°C to 200°C, 20°C to 150°C, 20°C to 120°C, 20°C to 100°C, 20°C to 90°C, 20°C to 80°C, 20°C to 70°C, 20°C to 60°C, 20°C to 50°C, 20°C to 40°C, 20°C to 30°C, 30°C to 200°C, 30°C to 150°C, 30°C to 120°C, 3 0°C to 100°C, 30°C to 90°C, 30°C to 80°C, 30°C to 70°C, 30°C to 60°C, 30°C to 50°C, 30°C to 40°C, 40°C to 200°C, 40°C to 150°C, 40°C to 120°C, 40°C to 100°C, 40°C to 90°C, 40°C to 80°C, 40°C to 70°C, 40°C to 60°C, 40 °C to 50°C, 50°C to 200°C, 50°C to 150°C, 50°C to 120°C, 50°C to 100°C, 50°C to 90°C, 50°C to 80°C, 50°C to 70°C, 50°C to 60°C, 60°C to 200°C, 60°C to 150°C, 60°C to 120°C, 60°C to 100°C, 60°C to 90°C, 60°C to 80°C , 60°C to 70°C, 70°C to 200°C, 70°C to 150°C, 70°C to 120°C, 70°C to 100°C, 70°C to 90°C, 70°C to 80°C, 80°C to 200°C, 80°C to 150°C, 80°C to 120°C, 80°C to 100°C, or 80°C to 90°C, or any and all sub-ranges formed by any of these endpoints.

[0100] High T g The monomer units consist of one or more (meth)acrylate monomers, preferably one or more monofunctional (meth)acrylate monomers.

[0101] In an embodiment, the high T g The monomer units are monovalent. In other embodiments, the high T gThe monomer units may be multivalent, wherein a single monomer unit contains two or more active sites that participate in crosslinking during curing. Examples of monovalent monomer units may include ethyl methacrylate and tert-butyl acrylate. Examples of multivalent monomer units may include divalent monomer units, such as dicyclopentadienyl acrylate.

[0102] In an embodiment, each high T g The monomer units (before polymerizing into the backbone of the acrylic copolymer) may independently be according to formula (II):

[0103]

[0104] (II)

[0105] in:

[0106] -A 1 is (C1-C 30 )alkyl or (C1-C 30 ) heteroalkyl, preferably (C1-C 30 ) a hydrocarbon group; and

[0107] -Z 1 It is -H or -CH3.

[0108] For example, in an embodiment, A 1 can be selected from methyl, ethyl, isopropyl, isobutyl, tert-butyl, substituted or unsubstituted (C6-C 12 )cycloalkyl, substituted or unsubstituted (C6-C 12 ) aryl or a combination thereof. In an embodiment, A 1 It may be selected from methyl, tert-butyl, isobornyl, cyclohexyl, or 3,3,5-trimethylcyclohexyl, phenyl, benzyl or a combination thereof.

[0109] The above embodiment is also applicable to A in the acrylic copolymer of formula (I). 1 .

[0110] In an embodiment, the high T g The monomer unit may include an acrylate (hydrocarbon) ester monomer, including but not limited to an acrylate (alkyl) ester monomer, an acrylate (cycloalkyl) ester monomer or an acrylate (aryl) ester monomer. Examples of acrylate (alkyl) ester monomers include acrylate and (meth) acrylate monomers such as (meth) methyl acrylate. Examples of acrylate (cycloalkyl) ester monomers include acrylate monomers and IBOA, IBOMA. Examples of acrylate (aryl) ester monomers include acrylate monomers and (meth) phenyl acrylate and (meth) benzyl acrylate.

[0111] Suitable high T gExamples of the monomer unit may include, but are not limited to, a monomer unit selected from the group consisting of 2-phenylethyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, tert-butyl acrylate, octadecyl methacrylate, octadecyl acrylate, propyl methacrylate, benzyl methacrylate, isobutyl methacrylate, ethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 2,2,2-trifluoroethyl methacrylate, isopropyl methacrylate, isobornyl acrylate, methyl methacrylate, isobornyl methacrylate, phenyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, 4-tert-butylcyclohexyl acrylate, 4-tert-butylcyclohexyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, substituted or unsubstituted (meth)acrylic acid (C6-C 12 )cycloalkyl ester, adamantyl (meth)acrylate, tricyclodecanemethanol mono(meth)acrylate, or a combination thereof.

[0112] Preferably, the high T of the acrylic copolymer g The monomer units are selected from methyl methacrylate, tert-butyl (meth)acrylate, isobornyl (meth)acrylate, phenyl (meth)acrylate and benzyl (meth)acrylate or a combination thereof.

[0113] High T in acrylic copolymers g The weight fraction of the monomers will vary depending on the desired properties of the acrylic copolymer (such as T g , molecular weight and gel content after curing).

[0114] As described herein, m of formula (I) is a polymeric high T gThe weight fraction of the monomer. In some embodiments, m is from 0 to 0.999, provided that the sum of m and n is at least 0.4. In further embodiments, m is greater than or equal to 0.01, such as greater than or equal to 0.05, greater than or equal to 0.1, greater than or equal to 0.15, greater than or equal to 0.2, greater than or equal to 0.25, greater than or equal to 0.30, greater than or equal to 0.35, greater than or equal to 0.40, greater than or equal to 0.45, greater than or equal to 0.50, greater than or equal to 0.55, or greater than or equal to 0.60. In an embodiment, m is 0.10 to 0.95, 0.10 to 0.95, 0.10 to 0.90, 0.10 to 0.85, 0.10 to 0.80, 0.10 to 0.75, 0.10 to 0.70, 0.10 to 0.60, 0.10 to 0.50, 0.10 to 0.40, 0.10 to 0.30, 0.10 to 0.20, 0.20 to 0.9 5. 0.20 to 0.90, 0.20 to 0.85, 0.20 to 0.80, 0.20 to 0.70, 0.20 to 0.60, 0.20 to 0.50, 0.20 to 0.40, 0.20 to 0.30, 0.30 to 0.95, 0.30 to 0.90, 0.30 to 0.85, 0.30 to 0.80, 0.30 to 0.70, 0.30 to 0 .60, 0.30 to 0.50, 0.30 to 0.40, 0.40 to 0.95, 0.40 to 0.90, 0.40 to 0.85, 0.40 to 0.80, 0.40 to 0.70, 0.40 to 0.60, 0.40 to 0.50, 0.50 to 0.95, 0.50 to 0.90, 0.50 to 0.85, 0.50 to 0.95, 0.5 From 0 to 0.90, 0.50 to 0.85, 0.50 to 0.80, 0.50 to 0.70, 0.50 to 0.60, 0.60 to 0.95, 0.60 to 0.90, 0.60 to 0.85, 0.60 to 0.80, 0.60 to 0.70, 0.70 to 0.95, 0.70 to 0.90, 0.70 to 0.85, or 0.70 to 0.80.

[0115] Low T g Monomer unit

[0116] The acrylic copolymers disclosed herein may include low T g Monomer unit. Low T g Monomer units are different from high T g monomer units, chromophore monomer units and additional monomer units. Therefore, low T g The monomer unit may not contain any of the following groups:

[0117] - chromophore moiety;

[0118] - a functional group as defined below for the additional monomeric unit.

[0119] In an embodiment, the acrylic copolymer comprises a polymerized low T g Monomer units, optionally with polymerized high T g Combination of monomer units. Polymerized low T g The monomer units may be the same or a combination of multiple types of unrelated monomer units such as two types of unrelated monomer units, three types of unrelated monomer units, four types of unrelated monomer units, or more than four types of unrelated monomer units. g The monomer unit may have a glass transition temperature (T g ) or less than 25°C Fox equation average T g As defined herein, the T of a monomer as referred to herein is g refers to the T of the homopolymer formed by the monomer g In the following embodiment: wherein the acrylic copolymer comprises two or more different low T g Monomer unit, T g Refers to low T g Fox equation average T of monomer unit g , as previously defined herein. In an embodiment, the low T g The monomer units have a Fox equation average T of less than 25°C, such as less than 20°C, less than 15°C, less than 10°C, less than 5°C, less than 0°C, less than -5°C, less than -10°C, less than -15°C, less than -20°C or less than -30°C. g In an embodiment, the low T g The monomer units have a Fox equation average T of -150°C to 24°C, such as preferably -80°C to 0°C, and most preferably -60°C to -10°C. g .

[0120] Low T g The monomer units consist of one or more (meth)acrylate monomers, preferably one or more monofunctional (meth)acrylate monomers.

[0121] In an embodiment, the low T g The monomer unit may be monovalent. In an embodiment, the low T g The monomer unit may include (meth)acrylate monomers, including acrylate monomers and methacrylate monomers. Examples of acrylate monomers include sec-butyl acrylate monomers and n-butyl acrylate monomers. Examples of methacrylate monomers include butyl methacrylate monomers and amyl methacrylate monomers.

[0122] In an embodiment, each low T g The monomer units (before polymerizing into the backbone of the acrylic copolymer) may independently be according to formula (II):

[0123]

[0124] (II)

[0125] in:

[0126] -A 2 (C4-C 30 )alkyl or (C4-C 30 ) heteroalkyl, preferably (C4-C 30 ) a hydrocarbon group; and

[0127] -Z 2 It is -H or -CH3.

[0128] In an embodiment, A 2 Straight or branched chain (C4-C 30 ) alkyl. In an embodiment, A 2 Selected from n-butyl, isobutyl, hexyl, 2-ethylhexyl, isooctyl, isodecyl, tridecyl, lauryl or a combination thereof.

[0129] The above embodiment is also applicable to A in the acrylic copolymer of formula (I). 2 .

[0130] Low T of acrylic copolymer g Further examples of monomer units include, but are not limited to, monomer units selected from the group consisting of n-butyl (meth)acrylate, isobutyl acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, nonyl acrylate, decyl (meth)acrylate, octyl (meth)acrylate, propyl acrylate, isobutyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, ethyl acrylate, sec-butyl acrylate, dodecyl acrylate, tetradecyl (meth)acrylate, isopropyl acrylate, amyl (meth)acrylate, benzyl acrylate, cyclohexyl acrylate, hexadecyl (meth)acrylate, 2-methylbutyl acrylate, 2-octyl acrylate, or combinations thereof.

[0131] Preferably, the acrylic copolymer has a low T g The monomer unit is n-butyl acrylate.

[0132] Polymerization of low T in acrylic copolymers gThe weight fraction of the monomers will vary depending on the desired properties of the acrylic copolymer (such as T g , molecular weight and gel content after curing).

[0133] As described herein, n of formula (I) is a polymeric low T gThe weight fraction of the monomer. In some embodiments, n is from 0 to 0.999, provided that the sum of m and n is at least 0.4. In an embodiment, n is greater than or equal to 0.001, such as greater than or equal to 0.02, greater than or equal to 0.05, greater than or equal to 0.10, greater than or equal to 0.15, greater than or equal to 0.20, greater than or equal to 0.25, greater than or equal to 0.30, greater than or equal to 0.35, greater than or equal to 0.40, greater than or equal to 0.45, greater than or equal to 0.50, greater than or equal to 0.55, greater than or equal to 0.60, greater than or equal to 0.65, greater than or equal to 0.70, greater than or equal to 0.75, or greater than or equal to 0.80.In embodiments, n is 0.001 to 0.989, 0.001 to 0.90, 0.001 to 0.80, 0.001 to 0.70, 0.001 to 0.60, 0.001 to 0.50, 0.001 to 0.40, 0.001 to 0.30, 0.001 to 0.20, 0.001 to 0.10, 0.001 to 0.05, 0.01 to 0.989, 0.01 to 0.90, 0.01 to 0.80, 0.01 to 0.70, 0.01 to 0.60, 0.01 to 0.50, 0.01 to 0.4 0, 0.01 to 0.30, 0.01 to 0.20, 0.01 to 0.10, 0.01 to 0.05, 0.05 to 0.989, 0.05 to 0.90, 0.05 to 0.80, 0.05 to 0.70, 0.05 to 0.60, 0.05 to 0.50, 0.05 to 0.40, 0.05 to 0.30, 0.05 to 0.20, 0.05 to 0.10, 0.10 to 0.989, 0.10 to 0.90, 0.10 to 0.80, 0.10 to 0.70, 0.10 to 0.60, 0.10 to 0. 50, 0.10 to 0.40, 0.10 to 0.30, 0.10 to 0.20, 0.20 to 0.989, 0.20 to 0.90, 0.20 to 0.80, 0.20 to 0.70, 0.20 to 0.60, 0.20 to 0.50, 0.20 to 0.40, 0.20 to 0.30, 0.30 to 0.989, 0.30 to 0.90, 0.30 to 0.80, 0.30 to 0.70, 0.30 to 0.60, 0.30 to 0.50, 0.30 to 0.40, 0.40 to 0.989, 0.30 to 0.90, From 0.90, 0.40 to 0.80, 0.40 to 0.70, 0.40 to 0.60, 0.40 to 0.50, 0.50 to 0.989, 0.50 to 0.90, 0.50 to 0.80, 0.50 to 0.70, 0.50 to 0.60, 0.60 to 0.989, 0.60 to 0.90, 0.60 to 0.80, 0.60 to 0.70, 0.70 to 0.989, 0.70 to 0.90, 0.70 to 0.80, 0.80 to 0.989, 0.80 to 0.90, or 0.90 to 0.989.

[0134] When the acrylic copolymer includes a low T g Monomer and high T g When both monomers are used, low T g Monomer and high T g The weight ratio of the monomers can be adjusted according to the desired properties of the acrylic copolymer, such as T g In an embodiment, the low T in the acrylic copolymer is adjusted by the gel content after curing. g Monomer and high Tg The weight ratio of the monomer units can be 10:1 to 1:9, 5:1 to 1:9, 2:1 to 1:9, 1:1 to 1:9, 10:1 to 1:5, 5:1 to 1:5, 2:1 to 1:5, 1:1 to 1:5, 10:1 to 1:5, or any and all subranges formed by any of these endpoints.

[0135] Chromophore monomer unit

[0136] In addition to at least one polymerized high T g Monomer units, or at least one polymerized low T g Monomer units, or preferably at least one polymerized high T g Monomer units and at least one polymerized low T g In addition to the combination of monomer units, the acrylic copolymer further includes at least one polymerized chromophore monomer unit. The chromophore monomer unit is different from the high T g Monomer unit, low T g Monomer units and additional monomer units.

[0137] The polymerized chromophore monomer units can act as photoinitiators and initiate the curing of the acrylic copolymer upon irradiation.A photoinitiator is generally a moiety that, upon absorption of light, generates reactive species (ions or free radicals) and initiates one or several chemical reactions or transformations.

[0138] The polymerized chromophore monomer unit comprises a free radical photoinitiator portion. The photoinitiator portion can be selected so that it is susceptible to activation of photons of wavelengths associated with the actinic radiation (e.g., ultraviolet radiation, visible light) intended for curing the curable composition. The Norrish II type (i.e., non-cleavable) photoinitiator portion does not decompose upon excitation, thereby providing a smaller possibility of leaching small molecules from the matrix composition. For reference, see, for example, A.Gilbert, J.Baggott: "Essentials of Molecular Photochemistry", Blackwell, London, 1991). The non-cleavable photoinitiator portion of the excitation does not decompose into free radicals upon excitation, but extracts hydrogen atoms from organic molecules, or more effectively extracts electrons from electron donors (such as amines or thiols). Electron transfer generates free radical anions on the photoinitiator, and generates free radical cations on the electron donor. Subsequently, a proton is transferred from the radical cation to the radical anion to generate two uncharged radicals; the radical on the electron donor is sufficiently reactive to abstract a hydrogen atom from most substrates.

[0139] The photoinitiator moiety includes a thioxanthone moiety, anthraquinone moiety or a camphorquinone moiety. Thioxanthone, anthraquinone and camphorquinone are examples of Norrish type II chromophores. Most amines with a C—H bond at the alpha position to the nitrogen atom and many thiols are electron donors.

[0140] In an embodiment, the polymerized chromophore monomer unit is a (meth)acrylate monomer having a Norrish Type II chromophore moiety selected from thioxanthone, anthraquinone, or camphorquinone.

[0141] In an embodiment, each chromophore monomer unit (before being polymerized into the backbone of the acrylic copolymer) may independently be according to formula (IV):

[0142] (IV)

[0143] in

[0144] A 3 is a monovalent residue comprising a Norrish type II chromophore moiety, particularly A 3 is X or -LX;

[0145] L is (C1-C 10 ) heterohydrocarbylene linker;

[0146] X is a monovalent residue of a Norrish type II chromophore moiety selected from thioxanthone, anthraquinone or camphorquinone, preferably thioxanthone;

[0147] Z 3 It is -H or -CH3.

[0148] In an embodiment, A in formula (IV) 3 is X or -LX, where L is (C1-C 10 ) heteroalkylene linker, and X is a monovalent residue of a Norrish type II chromophore. As used in the present disclosure, "residue" refers to an atom or group of atoms that constitutes a portion of a molecule, such as a portion of a Norrish type II chromophore. In other embodiments, A 3 is a monovalent residue of a Norrish type II chromophore. In an embodiment, X may be a monovalent residue of any of the above-mentioned Norrish type II chromophores. In an embodiment, A 3 A is a monovalent residue comprising thioxanthone, anthraquinone or camphorquinone. 3 is a monovalent residue comprising thioxanthone.

[0149] In particular, A of formula (I) 3 It may have the following formula (IVa) or (IVb):

[0150] (IVa)

[0151] (IVb)

[0152] Wherein, in formula (IVa) and formula (IVb):

[0153] L 1 is an alkylene group;

[0154] L 2 is a divalent linker comprising at least 2 carbon atoms;

[0155] R 1 and R 2 each independently selected from -H, halogen, alkyl, cycloalkyl, heterocycloalkyl, alkoxy, aryloxy, sulfanyl, sulfaryl, alkenyl, alkynyl, aryl, aralkyl, alkaryl, heteroaryl, -C(=O)R a 、-NR b R c 、alkylamino、alkylthiol、halogenated alkyl、-NO2、-CN、-C(=O)OR d 、-C(=O)NR b R c ;

[0156] R a is selected from optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted heterocycloalkyl, and optionally substituted aryl;

[0157] R b , R c and R d are independently selected from -H, alkyl and aryl.

[0158] In particular, in Formula (IVa) and Formula (IVb), R 1 and R 2 is independently -H, halogen, alkyl or alkoxy. More particularly, R 1 and R 2 is independently H or alkyl. Even more particularly, R 1 and R 2 is independently H or methyl. Still more particularly, R 1 and R 2 All are -H.

[0159] In Formula (IVa) and Formula (IVb), L 1 In particular, each L 1 L may independently be a linear or branched alkylene group having 1 to 6, 1 to 4 or 1 to 2 carbon atoms. More particularly, L 1is -CH2- or -CH(CH3)-. Even more particularly, L 1 It is -CH2-.

[0160] In Formula (IVa) and Formula (IVb), L 2 is a divalent linker containing at least 2 carbon atoms. 2 It can be an aromatic, aliphatic or alicyclic hydrocarbon linker, a polyether linker, a polyester linker, a polycarbonate linker, a polycaprolactone linker, a polyurethane (polyurethane) linker, a polyorganosiloxane linker, a polybutadiene linker, and combinations thereof. In particular, L 2 It may be selected from aromatic, aliphatic or cycloaliphatic hydrocarbon linkers, polyether linkers, polyester linkers and combinations thereof.

[0161] In Formula (IVa) and Formula (IVb), L 2 It may be -CH2-CH(OH)-CH2-, or a residue of a diol. As used herein, the term "residue of a diol" refers to a linker obtained by removing two OH groups from a diol. Examples of suitable diols include 1,3-propylene glycol, 1,3- or 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-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, norbornene dimethanol, norbornane dimethanol, tricyclodecane diols, tricyclodecane dimethanol, bisphenol A, B, F or S, hydrogenated bisphenol A, B, F or S, di-, tri- or tetraethylene glycol, di-, tri- or tetrapropylene glycol, di-, tri- or tetrabutylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly(ethylene glycol-co-propylene glycol), dianhydrohexitols (i.e., isosorbide, isomannide, isoidide), polybutadiene polyols, polyester polyols, polyether polyols, polyorganosiloxane polyols, polycarbonate polyols and their alkoxylated (e.g., ethoxylated and / or propoxylated) derivatives and derivatives obtained by ring-opening polymerization of ε-caprolactone initiated with one of the above polyols.

[0162] In Formula (IVa) and Formula (IVb), L 2 It may be -CH2-CH(OH)-CH2- or a divalent linker selected from one of formulas (A)-(E):

[0163] -(CR 22 R' 22 ) a -(A)

[0164] -[(CR 23 R’ 23 ) b -O] c -(CR 23 R’ 23 ) b -(B)

[0165] -[(CR 24 R’ 24 ) d -O] e -(CR 25 R’ 25 ) f -[O-(CR 26 R’ 26 ) d’ e’ - (C)

[0166] -[(CR 27 R’ 27 ) g -C(=O)O] h -(CR 28 R’ 28 ) i -或-(CR 28 R’ 28 ) i -[(CR 27 R’ 27 ) g -C(=O)O] h -(D)

[0167] -[(CR 29 R’ 29 ) j -O-C(=O)-(CR 30 R’ 30 ) k -C(=O)-O] l -(CR 29 R’ 29 ) j -(E)

[0168] wherein

[0169] R 22 , R’ 22 , R 25 , R’ 25 , R 29 , R’ 29 , R 30 and R’ 30 are independently H or alkyl; ​

[0170] R 23 , R' 23 , R 24 , R' 24 , R 26 , R' 26 , R 27 , R' 27 , R 28 and R' 28 are independently H or methyl;

[0171] a is 2 to 20;

[0172] b, d and d' are independently 2 to 4;

[0173] c is 1 to 20;

[0174] e and e' are independently 0 to 20, provided that at least one of q and q' is not 0;

[0175] f is 2 to 20;

[0176] g is 3 to 12;

[0177] h is 1 to 20;

[0178] i is 2 to 8;

[0179] j is 2 to 20;

[0180] k is 2 to 30;

[0181] l is 1 to 20.

[0182] In particular, in Formula (IVa) and Formula (IVb), L 2 may be -CH2-CH(OH)-CH2- or a divalent linker selected from alkylene groups such as 1,3-propanediyl, 1,3- or 1,4-butanediyl, 1,5-pentanediyl, 1,6-hexanediyl, 1,8-octanediyl, 1,9-nonanediyl, 1,10-decanediyl, 1,12-decanediyl, 2-methyl-1,3-propanediyl, 2,2-diethyl-1,3-propanediyl, 3-methyl-1,5-pentanediyl, 3,3-dimethyl-1,5-pentanediyl, 2,2-dimethyl-1,3-propanediyl, 2,4-diethyl-1,5-pentanediyl; alkoxylated (especially ethoxylated and / or propoxylated) derivatives of the abovementioned alkylene groups; esterified (especially by ring-opening polymerization of lactones such as ε-caprolactone) derivatives of the abovementioned alkylene groups; residues of di-, tri-, tetra- or polyoxyalkylene groups having no OH groups, such as di-, tri- or tetraethylene glycol, di-, tri- or tetrapropylene glycol, di-, tri- or tetrabutylene glycol, polyethylene glycol, polypropylene glycol, polybutylene glycol, poly(ethylene glycol-co-propylene glycol).

[0183] In a preferred embodiment, A of formula (I) 3 According to one of the following formulas (IVc) or (IVd):

[0184] (IVc)

[0185] (IVd)

[0186] Wherein h is 1 to 20.

[0187] Other suitable linker groups may be used, including other linker groups that do not have a carbonyl group.

[0188] The above A of formula (IV) 3 All the above embodiments are also applicable to A in the acrylic copolymer of formula (I). 3 .

[0189] The weight fraction of the polymerized chromophore monomer units in the acrylic copolymer may vary based on factors known in the art such as the desired curing time. As described herein, p of formula (I) is the weight fraction of the polymerized chromophore monomers. In an embodiment, p is greater than or equal to 0.001, such as greater than or equal to 0.005, or greater than or equal to 0.01. In an embodiment, p is 0.001 to 0.40, 0.001 to 0.30, 0.001 to 0.20, 0.001 to 0.10, 0.001 to 0.05, 0.001 to 0.03, 0.005 to 0.40, 0.005 to 0.30, 0.005 to 0.20, 0.005 to 0.10, 0.005 to 0.05, 0.005 to 0.03 or 0.005 to 0.02.

[0190] It should be understood that when the acrylic copolymer includes more than one unrelated type of polymerized chromophore monomer, the weight fraction p of the polymerized chromophore monomer in the acrylic copolymer is equal to the sum of the individual weight fractions of each unrelated type of polymerized chromophore monomer. Further, it should be understood that even if the chromophore monomer can be based only on T g Characterized by high T g Single or low T g Monomers, but for purposes of calculating the weight fractions m and n of formula (I), any monomer containing a chromophore moiety is not considered a high T g Single or low T g monomer.

[0191] Additional monomer units

[0192] The acrylic copolymers disclosed herein optionally include polymerized additional monomer units. The additional monomer units may include g Monomer unit, low Tg The monomer unit is a monomer unit copolymerized with the chromophore monomer unit. The additional monomer unit is different from the high T g Monomer unit, low T g Monomer units and chromophore monomer units.

[0193] The additional monomer units may contain functional groups selected from the following: polymerizable groups other than (meth)acrylate groups (i.e., vinyl, allyl, conjugated diene, alkenyl), acidic groups (i.e., carboxylic acid groups, phosphonic acid (-P(=O)(OH)2) groups, phosphonate (-P(=O)(OR)2) groups, sulfonic acid (-S(=O)2OH) groups, sulfonate (-S(=O)2OR) groups, phosphate (-OP(=O)(OR)2) groups, wherein each R is independently a counterion, a hydrogen atom or an optionally substituted hydrocarbon group), nitrogen-containing groups (i.e., amino, cyano or a heterocycle having one or more nitrogen ring atoms), hydroxyl, epoxy, carbonyl, acetoacetoxy, acetoacetamide groups, 1,1-dimethyl-3-oxobutyl (diacetone) groups, thiol groups, silane groups, ether bonds, ester bonds (not contained in the (meth)acrylate groups) and combinations thereof.

[0194] Preferably, the additional monomer unit comprises a functional group selected from an acidic group and a nitrogen-containing group. More preferably, the additional monomer unit comprises a functional group selected from a carboxylic acid group, a tertiary amine group or a heterocycle having one or more nitrogen ring atoms.

[0195] It should be emphasized that (meth)acrylic acid corresponds to an additional monomer. Therefore, the amount by weight of polymerized (meth)acrylic acid units (if present) should be included in the total amount of polymerized additional monomer units, rather than the polymerized high T g The total amount of monomer units.

[0196] In an embodiment, the additional monomer units may include other unsaturated monomer units (except the (meth) acrylic monomer units), such as vinyl amides, vinyl ethers, vinyl esters, vinyl oxazolidinones, (meth) acrylamides and combinations thereof. In an embodiment, the additional monomer units may include other monomer units polymerized in the acrylic copolymer, such as styrene derivatives and maleimides.

[0197] In an embodiment, the additional monomer unit may include epoxy, ether, ester, acid or ketone functional groups that are not polymerized in the acrylic copolymer. For example, the additional monomer unit may include caprolactone extended acrylate (SR49B, Sartomer), cyclic trimethylolpropane formal acrylate (SR531, Sartomer), propoxylated tetrahydrofurfuryl acrylate (SR611, Sartomer), β-carboxyethyl acrylate, glycidyl methacrylate, or 2-(2-ethoxyethoxy)ethyl acrylate (SR256), neopentyl monomethacrylate, tetrahydrofurfuryl (meth)acrylate, phenoxyethyl acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-cyanobutyl acrylate, 4-cyanobutyl acrylate, 2-cyanoethyl acrylate, cyanomethyl acrylate, and combinations thereof.

[0198] In embodiments, the additional monomer units may be monomers that act synergistically with the polymerized chromophore monomer units and / or reduce oxygen inhibition. Oxygen inhibition may limit surface cure and, thereby, the properties of the resulting cured product.

[0199] Common synergist functional groups that can act as synergists for Type II photoinitiators can include acidic groups, heterocycles having one or more nitrogen ring atoms, tertiary amine functional groups, alkyleneoxy functional groups (i.e., one or more oxyalkylene units), thiol groups, or other readily abstractable sources of hydrogen. Typical additional monomer units containing synergist functional groups are exemplified by monomers such as (meth)acrylic acid, dimethylaminoethyl acrylate (DMAEA), dimethylaminoethyl methacrylate (DMAEMA), diethylaminoethyl acrylate (DEAEA), diethylaminoethyl methacrylate (DEAEMA), N-vinyl pyrrolidone (NVP), N-vinyl caprolactam (VCAP), acryloyl morpholine (ACMO), dimethylacrylamide (DMAC), poly(ethylene oxide) mono(meth)acrylate, hydroxyethylethylene urea (meth)acrylate (HEEU(M)A), reaction products of cyclic anhydrides and hydroxyl functional (meth)acrylates, and combinations thereof.

[0200] In embodiments, the additional monomer units may include an amine synergist. Some examples of amine synergists include tertiary amines. When the monomer containing the amine synergist is combined with the Norrish II type chromophore of the polymerized chromophore monomer unit and included in the acrylic copolymer, the tertiary amine provides an active hydrogen donor site for the excited triplet state of the chromophore, thereby generating a reactive alkylamino free radical that can subsequently initiate polymerization. The tertiary amine can also convert the non-reactive peroxy species formed by the reaction between oxygen and the free radical into a reactive alkylamino free radical, thereby reducing the effect of oxygen on curing.

[0201] Examples of amine synergists that can be used as components of additional monomers for polymerization include low molecular weight tertiary amines (i.e., tertiary amines with a molecular weight less than 200 g / mol), such as triethanolamine, N-methyldiethanolamine. Other types of amine synergists are aminobenzoates, polymerizable aminobenzoates, polymeric aminobenzoates and mixtures thereof. Examples of aminobenzoates include 4-(dimethylamino)ethyl benzoate (EDB), 4-(dimethylamino)benzoic acid amyl ester, 4-(dimethylamino)benzoic acid 2-ethylhexyl ester and 4-(dimethylamino)benzoic acid 2-butoxyethyl ester (BEDB).

[0202] In an embodiment, the additional monomer unit is a (meth)acrylate monomer having a pendant amine functional group.

[0203] Any of the above synergists or aminic (amine-based) synergists may be the residues pendant from additional monomer units of the acrylic copolymers herein.

[0204] In embodiments, each additional monomer unit (before being polymerized into the backbone of the acrylic copolymer) may independently be according to formula (V):

[0205]

[0206] (V)

[0207] in:

[0208] -A 4 is (C1-C 30 )alkyl or (C1-C 30 ) heteroalkyl, preferably with a functional group selected from the following (C1-C 30 ) Heteroalkyl: acidic group, nitrogen-containing group, hydroxyl group, epoxy group, carbonyl group, acetoacetoxy group, acetoacetamide group, 1,1-dimethyl-3-oxobutyl (diacetone) group, thiol group, silane group, ether bond, ester bond and combinations thereof;

[0209] -Z 4 It is -H or -CH3.

[0210] A 4 Can contain any monovalent residue of the above-mentioned synergists. In an embodiment, Z 4 is -H or -CH3 and A 4 Yes – C(=O)-OR 4 , where R 4 is selected from H, dimethylaminomethyl, dimethylaminoethyl, morpholinyl, dimethylamino, -CH2-CH2-imidazolidinone or a combination thereof. 4 For -H and A 4Contains a heterocyclic ring with one or more nitrogen ring atoms, such as A 4 It can correspond to one of the following formulas:

[0211] .

[0212] The above embodiment is also applicable to A in the acrylic copolymer of formula (I). 4 and Z 4 .

[0213] The weight fraction of the additional monomers polymerized in the acrylic copolymer may vary according to factors well known in the art such as the desired cure time and the desired degree of cure. As described herein, q of formula (I) is the weight fraction of the additional monomers. In an embodiment, q is 0. In other embodiments, q is greater than or equal to 0.001, such as greater than or equal to 0.005, or greater than or equal to 0.01. In an embodiment, q is 0.001 to 0.20, 0.001 to 0.10, 0.001 to 0.05, 0.001 to 0.03, 0.005 to 0.20, 0.005 to 0.10, 0.005 to 0.05, 0.005 to 0.03, or 0.005 to 0.02.

[0214] Preferably, q is from 0 to 0.10.

[0215] The acrylic copolymers described herein can be g Monomer unit, low T g The acrylic copolymers are formed by controlled polymerization of the acrylic monomer units, the chromophore monomer units, and optionally additional monomers. The acrylic copolymers may be formed using common methods known in the art such as, but not limited to, solution acrylic polymerization.

[0216] Properties of acrylic copolymers

[0217] The acrylic copolymers described herein can be obtained by different monomer units (i.e., high T g Monomer unit, low T gThe acrylic copolymer can be formed by polymerization of a monomer unit, a chromophore monomer unit and optionally at least one additional monomer unit). Common methods known in the art include, but are not limited to, solution polymerization. Therefore, acrylic copolymers can be obtained by polymerizing different monomer units dissolved in a non-reactive solvent in the presence of an initiator. Solution polymerization can be carried out at a temperature of at least 50°C, preferably at least 60°C. Examples of suitable non-reactive solvents include toluene, heptane, ethyl acetate, methyl ethyl ketone (MEK), isopropanol, and combinations thereof. The initiator can be a thermal initiator. Thermal initiators are well known in the art and include, for example, peroxides (i.e., compounds containing oxygen-oxygen single bonds), especially inorganic persulfate compounds such as ammonium persulfate, potassium persulfate, and sodium persulfate; hydrogen peroxide; organic peroxides such as cumene hydroperoxide, tert-butyl hydroperoxide, acetyl peroxide, benzoyl peroxide, lauroyl peroxide; peracids such as peracetic acid and perbenzoic acid; redox initiators in which a reducing agent such as ferrous compounds promotes the decomposition of the peroxide; and other free radical generating materials such as azo initiators (i.e., compounds containing nitrogen-nitrogen double bonds), such as 2,2'-azobisisobutyronitrile, 4,4'-azobis(4-cyanovaleric acid) or 2,2'-azobis(2-methylbutyronitrile); and combinations thereof. The initiator may be added in an amount such that the total monomer:initiator weight ratio is from 100:1 to 1000:1. Solution polymerization typically provides a mixture of acrylic copolymers dissolved in a non-reactive solvent. The non-reactive solvent can be eliminated by heating. Reactive diluents can be added before eliminating the non-reactive solvent to form a curable composition as described in detail below. At the end of solution polymerization (i.e. before introducing reactive diluents), the mixture can have a solid content of 25% by weight to 70% by weight, preferably 30% by weight to 50% by weight, based on the gross weight of the mixture. The mixture can have a monomer residual amount of less than 2% by weight, particularly less than 1% by weight, more particularly less than 0.5% by weight, based on the gross weight of the mixture. Experimental conditions well known to those skilled in the art can be used to adjust the experimental parameters of solution polymerization (i.e. solid content, reaction temperature, reaction time and total monomer: initiator ratio), to produce relatively low molecular weight acrylic copolymers.

[0218] Preferably, the acrylic copolymer is not obtained by telomerization, i.e. not in the presence of a telogenic compound (i.e. a compound carrying at least one cleavable bond selected from CH, SH, PH, Si-H or CX, wherein X=Cl, Br or I), such as tetrabromomethane (CBr4), bromotrichloromethane (CBrCl3), dibromodichloromethane (CBr2Cl2), mercaptans, hydrogen disulfide.

[0219] In an embodiment, the acrylic copolymer may have a weight average molecular weight of at least 10,000 grams per mole (g / mol). In an embodiment, the acrylic copolymer may have a weight average molecular weight of 10,000 g / mol to 600,000 g / mol. In an embodiment, the acrylic copolymer may have a weight average molecular weight equal to or greater than 10,000 g / mol, equal to or greater than 25,000 g / mol, or even equal to or greater than 50,000 g / mol. In an embodiment, the acrylic copolymer may have a weight average molecular weight equal to or less than 600,000 g / mol, equal to or less than 500,000 g / mol, equal to or less than 400,000 g / mol, equal to or less than 300,000 g / mol, equal to or less than 200,000 g / mol, or even equal to or less than 100,000 g / mol. In an embodiment, the acrylic copolymer may have a molecular weight of 10,000 g / mol to 600,000 g / mol, 10,000 g / mol to 500,000 g / mol, 10,000 g / mol to 400,000 g / mol, 10,000 g / mol to 300,000 g / mol, 10,000 g / mol to 200,000 g / mol, 10,000 g / mol to 100,000 g / mol, 25,000 g / mol to 600,000 g / mol, 25,000 g / mol to 500,000 g / mol, 25,000 g / mol to 400,000 g / mol, 25,000 g / mol to 300,000 g / mol, 10,000 g / mol to 200,000 g / mol, 10,000 g / mol to 100,000 g / mol, g / mol to 300,000 g / mol, 25,000 g / mol to 200,000 g / mol, 25,000 g / mol to 100,000 g / mol, 50,000 g / mol to 600,000 g / mol, 50,000 g / mol to 500,000 g / mol, 50,000 g / mol to 400,000 g / mol, 50,000 g / mol to 300,000 g / mol, 50,000 g / mol to 200,000 g / mol, or even 50,000 g / mol to 100,000 g / mol, or any and all subranges formed by any of these endpoints.

[0220] In a preferred embodiment, the acrylic copolymer may have a weight average molecular weight of 10,000 g / mol to 100,000 g / mol, specifically 10,000 g / mol to 90,000 g / mol, specifically 11,000 g / mol to 80,000 g / mol, more specifically 12,000 g / mol to 75,000 g / mol, even more specifically 15,000 g / mol to 70,000 g / mol, still more specifically 15,000 g / mol to 65,000 g / mol.

[0221] In an embodiment, the acrylic copolymer may have a glass transition temperature T of equal to or less than -10°C. g To ensure that the curable composition is suitable for certain applications, such as use as a pressure-sensitive adhesive. In an embodiment, the acrylic copolymer may have a T of equal to or less than -10°C, such as equal to or less than -15°C, equal to or less than -20°C, equal to or less than -25°C, or even equal to or less than -30°C. g In embodiments, the acrylic copolymer may have a T of equal to or greater than -120 °C, equal to or greater than -100 °C, equal to or greater than -80 °C, or even equal to or greater than -60 °C. g In an embodiment, the acrylic copolymer may have a temperature range of -10°C to -120°C, -10°C to -100°C, -10°C to -80°C, -10°C to -60°C, -15°C to -120°C, -15°C to -100°C, -15°C to -80°C, -15°C to -60°C, -20°C to -120°C, -20°C to -100°C, -20°C to -20°C. C to -80°C, -20°C to -60°C, -25°C to -120°C, -25°C to -100°C, -25°C to -80°C, -25°C to -60°C, -30°C to -120°C, -30°C to -100°C, -30°C to -80°C, or even -30°C to -60°C, or any and all subranges formed by any of these endpoints. g .

[0222] In an embodiment, the acrylic copolymer has formula (V):

[0223] (V)

[0224] wherein m is from 0.2 to 0.8, n is from 0.1 to 0.8, p is from 0.001 to 0.2, and q is from 0 to 0.2.

[0225] In embodiments where q is greater than 0, Z 1 , Z2 , Z 3 and Z 4 is independently -H or -CH3. For example, in embodiments where q is greater than 0, Z 1 is -CH3, and Z 2 , Z 3 and Z 4 In the embodiment where q is equal to 0, Z 1 , Z 2 and Z 3 is independently -H or -CH3. For example, in embodiments where q is greater than 0, Z 1 is -CH3 and Z 2 and Z 3 is -H.

[0226] Curable composition

[0227] In an embodiment, the curable composition may include at least one of the acrylic copolymers described herein. In an embodiment, the curable composition may not include any additional photoinitiator other than the polymerized chromophore monomer units of the acrylic copolymer. That is, in an embodiment, the acrylic copolymer may be cured upon irradiation without any additional photoinitiator. In other embodiments, the curable composition may further include one or more photoinitiators in addition to the polymerized chromophore monomer units of the acrylic copolymer. In a preferred embodiment, the curable composition may be substantially free of photoinitiators other than the acrylic copolymer of the present invention. In particular, the curable composition may include less than 0.1%, particularly less than 0.05%, more particularly less than 0.001%, and even more particularly 0% by weight of a photoinitiator other than the acrylic copolymer of the present invention.

[0228] Preferably, the curable composition does not contain a (meth)acrylic copolymer other than the acrylic copolymer of the present invention.

[0229] In an embodiment, the curable composition may include one or more (meth)acrylate monomers or oligomers, diluents, (meth)acrylate oligomers, amine synergists, fillers, photoinitiators, slip agents, thickeners, slip agents, hindered amine light stabilizers, UV absorbing monomers or other auxiliary additives.

[0230] In some embodiments, at least one (meth)acrylate oligomer is included and selected from at least one of urethane acrylate and urethane methacrylate, and at least one (meth)acrylate monomer is included and selected from at least one of 2-hydroxyethyl methacrylate and isobornyl methacrylate.

[0231] In a preferred embodiment, the curable composition comprises an acrylic copolymer according to the present invention and a reactive diluent. The reactive diluent may be used together with the non-reactive solvent used to prepare the acrylic copolymer or completely replace the non-reactive solvent.

[0232] In an embodiment, the reactive diluent may have a viscosity of 3000 cP or less, as measured at 25°C by a Brookfield DV-III viscometer using a Spindle SC-27, such as 2750 cP or less, 2500 cP or less, 2250 cP or less, 2000 cP or less, 1750 cP or less, 1500 cP or less, or even 1250 cP or less. In an embodiment, the reactive diluent may have a viscosity of 5 cP or more, as measured at 25°C by a Brookfield DV-III viscometer using a Spindle SC-27, such as 25 cP or more, 50 cP or more, 100 cP or more, 250 cP or more, 500 cP or more, 750 cP or more, or even 1000 cP or more. In an embodiment,The reactive diluent may have a molecular weight of 25 cP to 3000 cP, 25 cP to 2750 cP, 25 cP to 2500 cP, 25 cP to 2250 cP, 25 cP to 2000 cP, 25 cP to 1750 cP, 25 cP to 1500 cP, 25 cP to 1250 cP, 25 cP to 3000 cP, 25 cP to 2750 cP, 25 cP to 2500 cP, 25 cP to 2250 cP, 25 cP to 2000 cP, 25 cP to 1750 cP, 25 cP to 1500 cP, 25 cP to 1250 cP, 50 cP to 3000 cP, 50 cP to 2750 cP, 50 cP to 2500 cP, 50 cP to 2250 cP, 50 cP to 2000 cP, 50 cP to 1750 cP, 50 cP to 1500 cP, 50 cP to 1250 cP, 100 cP to 3000 cP, 100 cP to 2750 cP, 100 cP to 2500 cP, 100 cP to 2250 cP, 100 cP to 2000 cP, 100 cP to 1750 cP, 100 cP to 1500 cP, 100 cP to 1250 cP, 250 cP to 3000 cP, 250 cP to 2750 cP, 250 cP to 2500 cP, 250 cP to 2250 cP, 250 cP to 2000 cP, 250 cP to 1750 cP, 250 cP to 1500 cP, 250 cP to 1250 cP, 500 cP to 3000 cP, 500 cP to 2750 cP, 500 cP to 2500 cP, 500 cP to 2250 cP, 500 cP to 2000 cP, 500 cP to 1750 cP, 500 cP to 1500 cP, 500 cP to 1250 cP, 750 cP to 3000 cP, 750 cP to 2750 cP, 750 cP to 2500 cP, 750 cP to 2250 cP, 750 cP to 2000 cP, 750 cP to 1750 cP, 750 cP to 1500 cP, 750 cP to 1250 cP, 1000 cP to 3000 cP, 1000 cP to 2750 cP, 1000 cP to 2500 cP, 1000 cP to 2250 cP, 1000 cP to 2000 cP, 1000 cP to 1750 cP, 1000 cP to 1500 cP, or even 1000 cP to 1250 cP, or any and all sub-ranges of viscosity formed by any of these endpoints,As measured by a Brookfield DV-III viscometer using a Spindle SC-27 at 25°C.

[0233] The reactive diluent may include at least one radically polymerizable diluent. The reactive diluent may include a mixture of radically polymerizable diluents. When the reactive diluent includes a mixture of radically polymerizable diluents, the embodiments related to viscosity apply to the mixture of radically polymerizable diluents.

[0234] As used herein, a free radical polymerizable diluent is a compound having at least one polymerizable carbon-carbon double bond and preferably having a suitable viscosity as defined above. A polymerizable carbon-carbon double bond is capable of participating in free radical polymerization, wherein at least one of the carbon atoms of the double bond is covalently bound to another atom (particularly a carbon atom) in a second molecule. In particular, a reactive diluent may include at least one free radical polymerizable diluent selected from the group consisting of (meth) acrylates, vinyl ethers, vinyl amides, vinyl oxazolidinones, and combinations thereof. These diluents may be monofunctional (i.e., with a single polymerizable carbon-carbon double bond) or multifunctional (i.e., with at least two polymerizable carbon-carbon double bonds). These diluents may be selected to provide the target final properties of the cured formulation, as long as they provide sufficient viscosity reduction of the acrylic copolymer while producing sufficient properties when the curable composition is cured.

[0235] The reactive diluent may include a monofunctional (meth)acrylate (i.e., a monomer with a single (meth)acrylate group). Examples of suitable monofunctional (meth)acrylates include mono(meth)acrylates of aliphatic alcohols (wherein the aliphatic alcohol may be linear, branched, or alicyclic and may be a monohydric alcohol, a dihydric alcohol, or a polyhydric alcohol, provided that only one hydroxyl group is esterified with (meth)acrylic acid); 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 diols (such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, and polypropylene glycol); ) acrylates; mono(meth)acrylates of monoalkyl ethers of glycols and oligomeric glycols; mono(meth)acrylates of alkoxylated (e.g. ethoxylated and / or propoxylated) aliphatic alcohols (wherein the aliphatic alcohol may be linear, branched or alicyclic and may be a monohydric alcohol, a dihydric alcohol or a polyhydric alcohol, provided that only one hydroxyl group of the alkoxylated aliphatic alcohol is esterified with (meth)acrylic acid); mono(meth)acrylates of alkoxylated (e.g. ethoxylated and / or propoxylated) aromatic alcohols (such as alkoxylated phenols); caprolactone mono(meth)acrylate; and the like.The following compounds are specific examples of mono(meth)acrylate functional monomers suitable for use: methyl(meth)acrylate; ethyl(meth)acrylate; n-propyl (meth)acrylate; n-butyl (meth)acrylate; isobutyl (meth)acrylate; n-hexyl (meth)acrylate; 2-ethylhexyl (meth)acrylate; n-octyl (meth)acrylate; isooctyl (meth)acrylate; n-decyl (meth)acrylate; n-dodecyl (meth)acrylate; tridecyl (meth)acrylate; tetradecyl (meth)acrylate; hexadecyl (meth)acrylate; 2-hydroxyethyl (meth)acrylate; 2- and 3-hydroxypropyl (meth)acrylate; 2-methoxyethyl (meth)acrylate; 2-ethoxyethyl (meth)acrylate; 2- and 3-ethoxypropyl (meth)acrylate; tetrahydrofurfuryl (meth)acrylate; alkoxylated tetrahydrofurfuryl (meth)acrylate; 2-(2-ethoxyethoxy)ethyl (meth)acrylate; cyclohexyl (meth)acrylate; (meth) Glycidyl acrylate; isodecyl (meth)acrylate; lauryl (meth)acrylate; 2-phenoxyethyl (meth)acrylate; alkoxylated phenol (meth)acrylate; alkoxylated nonylphenol (meth)acrylate; cyclic trimethylolpropane formal (meth)acrylate; isobornyl (meth)acrylate; tricyclodecane methanol (meth)acrylate; tert-butyl cyclohexanol (meth)acrylate; trimethyl cyclohexanol (meth)acrylate; diethylene glycol monomethyl ether (meth)acrylate; diethylene glycol monoethyl ether (meth)acrylate; diethylene glycol monobutyl ether (meth)acrylate; triethylene glycol monoethyl ether (meth)acrylate; ethoxylated lauryl (meth)acrylate; methoxy polyethylene glycol (meth)acrylate; hydroxyethyl butyl carbamate (meth)acrylate; 3-(2-hydroxyalkyl) oxazolidinone (meth)acrylate; and combinations thereof.

[0236] The reactive diluent may include a monofunctional (meth)acrylate with one or more of the following groups: a ring or ring system (i.e., one or more rings selected from aromatic rings and / or (hetero)cycloaliphatic rings, which may be fused and / or bridged), a C7-C20 hydrocarbon chain (i.e., a straight or branched chain carrying only carbon and hydrogen atoms, wherein the number of carbon atoms in the chain is from 7 to 20), one or more oxyalkylene units (such as oxyethylene, oxypropylene and / or oxybutylene units), one or more ring-opened ester units derived from lactones (such as ε-caprolactone), and combinations thereof. Examples of such monofunctional (meth)acrylates are isobornyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, phenol (meth)acrylate, nonylphenol (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate; lauryl (meth)acrylate; tridecyl (meth)acrylate, stearyl (meth)acrylate, (poly)caprolactone mono(meth)acrylate, di-, tri-, tetra- or polyethylene glycol mono(meth)acrylate, di-, tri-, tetra- or polyethylene glycol monomethyl ether (meth)acrylate, di-, tri-, tetra- or polyethylene glycol monoethyl ether (meth)acrylate, and alkoxylated (i.e. ethoxylated and / or propoxylated) derivatives thereof, and combinations thereof.

[0237] The reactive diluent may include a T g Monofunctional (meth)acrylate monomers: above 25°C, preferably above 30°C, more preferably above 35°C, even more preferably above 40°C, more preferably also above 45°C, more preferably also above 50°C. Examples of such monomers include 2-phenylethyl methacrylate, neopentyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, tert-butyl acrylate, octadecyl methacrylate, octadecyl acrylate, glycidyl methacrylate, propyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, isobutyl methacrylate, glycidyl methacrylate, ethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 2-hydroxypropyl methacrylate, 2,2,2-trifluoroethyl methacrylate, methacrylate. 2-Hydroxyethyl ester, isopropyl methacrylate, isobornyl acrylate, methyl methacrylate, butyl cyanoacrylate, isobornyl methacrylate, phenyl methacrylate, 2-cyanobutyl acrylate, tert-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 4-tert-butylcyclohexyl acrylate, 4-tert-butylcyclohexyl methacrylate, ethyl cyanoacrylate, methyl cyanoacrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, substituted or unsubstituted (meth)acrylic acid (C6-C12 )cycloalkyl ester, adamantyl (meth)acrylate, dicyclopentyl (meth)acrylate, tricyclodecanemethanol mono(meth)acrylate, 2-phenoxyethyl methacrylate, or a combination thereof.

[0238] The reactive diluent may include a multifunctional (meth)acrylate (i.e., a monomer with at least two (meth)acrylate groups), such as 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. meth)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-nonanediol di(meth)acrylate; 1,12-dodecanediol di(meth)acrylate Neopentyl glycol di(meth)acrylate; 2-methyl-2,4-pentanediol di(meth)acrylate; polybutadiene di(meth)acrylate; cyclohexane-1,4-dimethanol di(meth)acrylate; tricyclodecane dimethanol di(meth)acrylate; metal di(meth)acrylate; modified metal di(meth)acrylate; glyceryl di(meth)acrylate; glyceryl tri(meth)acrylate; trimethylolethane tri(meth)acrylate; trimethylolethane di(meth)acrylate; trimethylolpropane tri(meth)acrylate; trimethylolpropane di(meth)acrylate acrylates; pentaerythritol di(meth)acrylate; pentaerythritol tri(meth)acrylate; pentaerythritol tetra(meth)acrylate, di(trimethylolpropane) diacrylate; di(trimethylolpropane) triacrylate; di(trimethylolpropane) tetraacrylate, sorbitol penta(meth)acrylate; di(pentaerythritol) tetraacrylate; di(pentaerythritol) pentaacrylate; di(pentaerythritol) hexa(meth)acrylate; tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate; and alkoxylated (e.g., ethoxylated and / or propoxylated) derivatives thereof; and combinations thereof.

[0239] Reactive diluents may include vinyl ethers such as dodecyl vinyl ether, hydroxybutyl vinyl ether, cyclohexane dimethylol divinyl ether, and DVE-3 (triethylene glycol divinyl ether), and combinations thereof.

[0240] The reactive diluent may include vinyl amides such as N-vinyl pyrrolidone (NVP), N-vinyl caprolactam (V-CAP), and combinations thereof.

[0241] The reactive diluent may include a vinyl oxazolidinone, such as vinyl methyl oxazolidinone (VMOX).

[0242] In a preferred embodiment, the reactive diluent preferably includes a monofunctional (meth)acrylate, a multifunctional (meth)acrylate, or a mixture of a monofunctional (meth)acrylate and a multifunctional (meth)acrylate.

[0243] The amount of reactive diluent in the curable composition can vary according to the desired viscosity. In an embodiment, the curable composition may include 20% to 80% by weight of reactive diluent based on the weight of the curable composition. In an embodiment, the curable composition may include 20% to 80% by weight of reactive diluent based on the weight of the curable composition. In an embodiment, the curable composition may include 20% to 25% by weight, 30% to 35% by weight, or even 40% by weight of reactive diluent based on the weight of the curable composition. In an embodiment, the curable composition may include 80% to 75% by weight, 70% to 65% by weight, or even 60% by weight of reactive diluent based on the weight of the curable composition. In embodiments, the amount by weight of the reactive diluent in the curable composition may be 20% to 80%, 20% to 75%, 20% to 70%, 20% to 75%, 20% to 60%, 25% to 80%, 20% to 75%, 25% to 70%, 25% to 75%, 25% to 60%, 30% to 80%, 30% to 75%, 30% to 70%, 30% to 75%, 30% to 60%, 35% to 80%, 35% to 75%, 35% to 70%, 35% to 75%, 35% to 60%, 40% to 80%, 40% to 75%, 40% to 70%, 40% to 75%, or even 40% to 60%, or any and all subranges formed by any of these endpoints, based on the total weight of the curable composition.

[0244] In a preferred embodiment, the curable composition may comprise at least 5 wt %, at least 10 wt %, at least 15 wt %, at least 20 wt %, at least 30 wt %, at least 40 wt % or at least 50 wt % of a monofunctional (meth) acrylate monomer as defined above, based on the total weight of the curable composition. Alternatively, the curable composition may comprise less than 5 wt %, less than 4 wt %, less than 3 wt %, less than 2 wt %, less than 1 wt % or even 0 wt % of a monofunctional (meth) acrylate monomer as defined above, based on the total weight of the curable composition.

[0245] In a preferred embodiment, the curable composition may comprise at least 5 wt %, at least 10 wt %, at least 15 wt %, at least 20 wt %, at least 30 wt %, at least 40 wt % or at least 50 wt % of a multifunctional (meth) acrylate monomer as defined above, based on the total weight of the curable composition. Alternatively, the curable composition may comprise less than 5 wt %, less than 4 wt %, less than 3 wt %, less than 2 wt %, less than 1 wt % or even 0 wt % of a multifunctional (meth) acrylate monomer as defined above, based on the total weight of the curable composition.

[0246] In an embodiment, the weight ratio of the acrylic copolymer to the reactive diluent in the curable composition may be 4:1 to 1:4, such as 3:1 to 1:4, 2:1 to 1:4, 1:1 to 1:4, 3:1 to 1:3, 2:1 to 1:3, 1:1 to 1:3, 3:1 to 1:2, 2:1 to 1:2, 1:1 to 1:2, 3:1 to 1:1, or even 2:1 to 1:1, or any and all subranges formed by any of these endpoints.

[0247] In a preferred embodiment, the curable composition comprises an acrylic copolymer according to the present invention and a (meth)acrylate functionalized oligomer.

[0248] The (meth)acrylate functionalized oligomer may be selected to enhance properties such as flexibility, strength, and / or modulus of the cured polymer prepared by curing the curable composition of the present invention.

[0249] The (meth)acrylate functionalized oligomer may have 1 to 18 (meth)acrylate groups, specifically 2 to 6 (meth)acrylate groups, more specifically 2 to 6 acrylate groups.

[0250] The (meth)acrylate functionalized oligomer may have a number average molecular weight equal to or greater than 600 g / mol, specifically 800 to 15,000 g / mol, more specifically 1,000 to 5,000 g / mol.

[0251] In particular, the curable composition may comprise a (meth)acrylate functionalized oligomer selected from epoxy (meth)acrylates, polyester (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, (meth)acrylated poly (meth)acrylates, and mixtures thereof.

[0252] Non-limiting examples of epoxy (meth)acrylates are reaction products of epoxides such as glycidyl ethers, glycidyl esters, alicyclic epoxides or epoxides obtained by epoxidation of mono- and / or polyunsaturated compounds and (meth)acrylating agents such as (meth)acrylic acid, (meth)acrylic anhydride, (meth)acryloyl chloride or combinations thereof. The epoxide may be an epoxide EPOX selected from the following: 1,2,3,4-diepoxybutane; 1,2,4,5-diepoxypentane; 1,2,5,6-diepoxyhexane; 1,2,7,8-diepoxyoctane; 1,2,9,10-diepoxydecane; 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 resin, 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-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di(3,4-epoxycyclohexane) 1,2- or 1,3-propylene glycol diglycidyl ether, 1,2-, 1,3- or 1,4-butanediol diglycidyl ether, 1,5-pentanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,7-hexanediol diglycidyl ether, 1,8-octanediol diglycidyl ether, 1,9-nonanediol diglycidyl ether, 1,10-decanediol diglycidyl ether, 1,12-dodecanediol diglycidyl ether, 2-methyl-1,3-propanediol diglycidyl ether diglycidyl ether of 2,2-diethyl-1,3-propanediol, diglycidyl ether of 3-methyl-1,5-pentanediol, diglycidyl ether of 3,3-dimethyl-1,5-pentanediol, diglycidyl ether of 2,4-diethyl-1,5-pentanediol, diglycidyl ether of 3,3-butylethyl-1,5-pentanediol, diglycidyl ether of di-, tri- or tetra-(ethylene glycol) diglycidyl ether, di-, tri- or tetra-(1,2-propylene glycol) diglycidyl ether, di-, tri- or tetra-(1,3-propylene glycol) diglycidyl ether, di-, tri- or tetra-(1,4-butylene glycol) diglycidyl ether, poly(ethylene glycol) diglycidyl ether, poly(propylene glycol) diglycidyl ether, poly(trimethylene glycol) diglycidyl ether, poly(tetramethylene glycol) diglycidyl ether, poly(ethylene glycol-co-propylene glycol) diglycidyl ether, glycerol triglycidyl ether, polyglycerol polyglycidyl ether, trimethylolmethane triglycidyl ether, trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, di( trimethylolpropane) tetraglycidyl ether, pentaerythritol tetraglycidyl ether, diglycidyl cyclohexane dicarboxylate, cyclohexane diglycidyl ether, cyclohexane-1,4-dimethanol diglycidyl ether, tricyclodecane dimethanol diglycidyl ether, isosorbide diglycidyl ether, catechol diglycidyl ether, resorcinol diglycidyl ether, cardol diglycidyl ether, phloroglucinol triglycidyl ether, pyrogallol (py triglycidyl ether of 1,2-dihydroxyphenyl)methane, triglycidyl ether of 1,2-dihydroxyphenyl) ...

[0253] A non-limiting example of polyester (meth) acrylate is the reaction product of a hydroxyl-terminated polyester polyol and a (meth) acrylate agent (such as (meth) acrylic acid, (meth) acrylic anhydride, (meth) acryloyl chloride or a combination thereof). The reaction process may be carried out so that a significant concentration of residual hydroxyl groups is retained in the polyester (meth) acrylate, or may be carried out so that all or substantially all of the hydroxyl groups of the polyester polyol are (meth) acrylated. The polyester polyol may be made by a polycondensation reaction of a polyhydroxyl functional component (particularly a diol) and a polycarboxylic acid functional compound (particularly a dicarboxylic acid or anhydride). To prepare the polyester (meth) acrylate, the hydroxyl groups of the polyester polyol are subsequently partially or completely esterified by reaction with a (meth) acrylate agent. The polyester (meth) acrylate may also be synthesized by reacting a hydroxyl-containing (meth) acrylate (such as a hydroxyalkyl (meth) acrylate (e.g., hydroxyethyl acrylate)) with a poly (poly) carboxylic acid. The polyhydroxy-functional and polycarboxylic acid-functional components may each have a linear, branched, alicyclic, or aromatic structure, and may be used alone or as a mixture.

[0254] Non-limiting examples of polyether (meth) acrylates are condensation products of polyether alcohols as polyether polyols with (meth) acrylate agents (e.g., (meth) acrylic acid, (meth) acrylic anhydride, (meth) acryloyl chloride or combinations thereof). Suitable polyether alcohols may be straight or branched substances containing ether bonds and terminal hydroxyl groups. Polyether alcohols may be prepared by ring-opening polymerization of epoxides and other oxygen-containing heterocyclic compounds (e.g., ethylene oxide, 1,2-propylene oxide, butylene oxide, tetrahydrofuran and combinations thereof) with initiator molecules. Suitable initiator molecules include water, hydroxyl functional materials, polyester polyols and amines. Polyether alcohols may also be obtained by condensation of diols such as glycols.

[0255] The non-limiting examples of carbamate (meth) acrylate are the condensation reaction products of at least one polyisocyanate (e.g., diisocyanate, triisocyanate), at least one polyol (such as polyether polyol or polyester polyol) and hydroxyl-functional (meth) acrylate (such as 2-hydroxyethyl (meth) acrylate or 3-hydroxypropyl (meth) acrylate) to provide terminal (meth) acrylate groups. For example, carbamate (meth) acrylate may contain two, three, four or more (meth) acrylate groups per molecule. The order of addition of the components for preparing carbamate (meth) acrylate is well known in the art. For example, hydroxyl-functional (meth) acrylate may first react with polyisocyanate to obtain isocyanate-functional (meth) acrylate, which is then reacted with polyol. In yet another embodiment, polyisocyanate may first react with polyol to obtain isocyanate-functional polyol, which is then reacted with hydroxyl-functional (meth) acrylate. Alternatively, all components may be combined and reacted simultaneously.

[0256] A non-limiting example of a (meth)acrylated poly(meth)acrylate is a material having an oligomeric (meth)acrylic backbone functionalized with one or more (meth)acrylate groups (which may be at the end of the oligomer or attached to the acrylic backbone). The (meth)acrylic backbone may be a homopolymer, a random copolymer or a block copolymer comprising repeating units of a (meth)acrylic monomer. The (meth)acrylic monomer may be any monomeric (meth)acrylate such as a C1-C6 alkyl (meth)acrylate and a functionalized (meth)acrylate such as a (meth)acrylate with hydroxyl, carboxylic acid and / or epoxy groups. (Meth)acrylated poly(meth)acrylates can be prepared using any procedure known in the art, such as by oligomerizing (meth)acrylic monomers, at least a portion 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 functionalized poly(meth)acrylates, which are subsequently reacted with one or more (meth)acrylate-containing reactants to introduce the desired (meth)acrylate functional groups.

[0257] The curable composition may comprise 0 to 80 wt %, in particular 5 to 75 wt %, more in particular 10 to 70 wt %, even more in particular 15 to 60 wt %, still more in particular 20 to 50 wt % of (meth)acrylate functional oligomer, based on the total weight of the curable composition. In particular, the curable composition may comprise 0 to 50 wt %, 1 to 45 wt %, 5 to 40 wt %, 10 to 35 wt % or 15 to 30 wt % of (meth)acrylate functional oligomer, based on the total weight of the polymerizable components.

[0258] The curable composition may include an amine synergist. Some examples of amine synergists include tertiary amines. When the monomer containing the amine synergist is combined with the Norrish II type chromophore of the polymerized chromophore monomer unit and is included in the acrylic copolymer, the tertiary amine provides an active hydrogen donor site for the excited triplet state of the chromophore, thereby generating reactive alkylamino free radicals that can subsequently initiate polymerization. The tertiary amine can also convert the non-reactive peroxy species formed by the reaction between oxygen and the free radical into reactive alkylamino free radicals, thereby reducing the effect of oxygen on curing. Examples of amine synergists that can be used as components of additional monomers for polymerization include low molecular weight tertiary amines (i.e., tertiary amines with a molecular weight less than 200 g / mol), such as triethanolamine, N-methyldiethanolamine. Other types of amine synergists are aminobenzoates, polymerizable aminobenzoates, polymeric aminobenzoates and mixtures thereof. Examples of aminobenzoic acid esters include ethyl 4-(dimethylamino)benzoate (EDB), pentyl 4-(dimethylamino)benzoate, 2-ethylhexyl 4-(dimethylamino)benzoate, and 2-butoxyethyl 4-(dimethylamino)benzoate (BEDB).

[0259] The curable composition may contain 0.1 to 10%, particularly 1 to 5%, of an amine synergist, based on the weight of the curable composition. Alternatively, the curable composition may be substantially free of amine synergists (i.e., when the acrylic copolymer contains polymerized additional monomer units that exhibit synergist functionality as described above, such as polymerized additional monomer units containing tertiary amine functional groups). In particular, the curable composition may contain less than 0.1%, particularly less than 0.05%, more particularly less than 0.001%, even more particularly 0% by weight of amine synergists other than the acrylic copolymer of the present invention.

[0260] In an embodiment, the curable composition may be liquid at a temperature of 25°C ± 2°C. In an embodiment, the curable composition may have a viscosity of 50,000 cP or less, such as 45,000 cP or less, 40,000 cP or less, 35,000 cP or less, 30,000 cP or less, 25,000 cP or less, 20,000 cP or less, 15,000 cP or less, 12,500 cP or less, or even 10,000 cP or less, measured at 60°C by a Brookfield DV-III viscometer using a Spindle SC-27. Such viscosity characteristics facilitate spreading of the composition on a substrate to form a film.

[0261] In a preferred embodiment, the curable composition may have a viscosity of 50,000 cP or less, such as 45,000 cP or less, 40,000 cP or less, 35,000 cP or less, 30,000 cP or less, 25,000 cP or less, 20,000 cP or less, 15,000 cP or less, 12,500 cP or less, or even 10,000 cP or less, as measured at 25°C by a Brookfield DV-III viscometer using a Spindle SC-27.

[0262] In embodiments, the curable composition may include less than 1 wt % of a solvent and less than 1 wt % of water, or be free of solvent and free of water. In embodiments, a film or coating may be formed by curing the curable composition.

[0263] Method for preparing and curing curable composition

[0264] The present invention also relates to a method for preparing a curable composition according to the present invention. The method for preparing a curable composition comprises the following steps:

[0265] - preparing an acrylic copolymer according to the invention dissolved in a non-reactive solvent;

[0266] - adding a reactive diluent to obtain a diluted curable composition;

[0267] - removing at least part of the non-reactive solvent from the diluted curable composition to obtain the curable composition according to the present invention.

[0268] The acrylic copolymer dissolved in the non-reactive solvent can be prepared by solution polymerization as described above. The acrylic copolymer, the non-reactive solvent and the reactive diluent can be as defined above. The non-reactive solvent can be at least partially removed by heating, for example, at a temperature of 40°C or higher, particularly 50°C or higher, more particularly 60°C or higher. The amount of non-reactive solvent after the removal step can be less than 1%, less than 0.5% or even 0%, based on the weight of the non-reactive solvent based on the weight of the curable composition.

[0269] The present invention also relates to a method of curing a curable composition according to the present invention.The method of curing a curable composition comprises curing the curable composition.

[0270] The curing step may be carried out at ambient temperature (ie 10-30°C).

[0271] The curing step can be performed by irradiating the composition with a light source having a wavelength and / or intensity capable of activating the polymerized chromophore monomer units of the acrylic copolymer of the present invention and causing crosslinking of the acrylic copolymer and / or the reactive diluent. The curing step can be performed in the absence of a photoinitiator other than the acrylic copolymer of the present invention. In other words, the curable composition can contain less than 0.1 wt%, particularly less than 0.05 wt%, more particularly less than 0.001 wt%, even more particularly 0 wt% of a photoinitiator other than the acrylic copolymer of the present invention, based on the weight of the curable composition.

[0272] The method of curing the curable composition of the present invention may not involve a pre-curing step, in particular a step of curing at least part of the reactive diluent before crosslinking the acrylic copolymer of the present invention, for example by irradiating the curable composition with a light source having a long wavelength and / or low intensity in the presence of a photoinitiator other than the acrylic copolymer of the present invention. As used herein, a light source having a long wavelength and / or low intensity is a light source that is unable to activate the polymerized chromophore monomer units of the acrylic copolymer of the present invention and cause the acrylic copolymer and / or the reactive diluent to crosslink. An example of a light source having a long wavelength and / or low intensity is black light (as opposed to an LED-UV lamp that is capable of activating a chromophore comprising a thioxanthone moiety). Preferably, the method of curing the curable composition of the present invention comprises a curing step in which at least part of the reactive diluent and at least part of the acrylic copolymer of the present invention are cured simultaneously. Without being bound by theory, such a curing method is believed to enable at least part of the reactive diluent to be grafted onto at least part of the oligomer of the present invention.

[0273] Cured composition

[0274] The acrylic copolymer described herein can be cured in combination with a reactive diluent (preferably at least one (meth)acrylate monomer) or at least one (meth)acrylate oligomer or both to obtain a cured composition. In an embodiment, the cured composition is the product of photocuring a composition comprising an acrylic copolymer according to an embodiment described herein and a reactive diluent (preferably at least one (meth)acrylate monomer), which exhibits: an APHA-10mm initial color of 0.1 to 50; an initial yellowness (b) of 0.01 to 2 ); and a T equal to or greater than 0°C g .

[0275] In some embodiments, the cured composition exhibits an APHA-10 mm initial color of 0.1 to 50, 0.1 to 45, 0.1 to 40, 0.5 to 45, 1.0 to 45, 2.0 to 40, 3.0 to 40, 4.0 to 40, 5.0 to 40, 7.0 to 40, or 10.0 to 40. In other embodiments, the cured composition exhibits an APHA-10 mm initial color of 0.1 to 10, 0.3 to 9, 0.5 to 9, 1 to 9, 2 to 9, 2.5 to 9, 2.5 to 8, 2.5 to 7.5, or 3 to 7.

[0276] In some embodiments, the cured composition exhibits an initial yellowness (b) of 0.01 to 2, 0.05 to 2, 0.1 to 2, 0.1 to 1.7, 0.1 to 1.5, 0.2 to 1.5, 0.3 to 1.5, 0.4 to 1.5, 0.4 to 1.4, 0.4 to 1.3, or 0.5 to 1.2. In other embodiments, the cured composition exhibits an initial yellowness (b ) is from 0.01 to 1.0, 0.05 to 1.0, 0.1 to 1.0, 0.1 to 0.7, 0.1 to 0.6, 0.15 to 0.55 or 0.2 to 0.5.

[0277] In an embodiment, the cured composition may have a T of 0°C or greater, such as 5°C or greater, 10°C or greater, 15°C or greater, 20°C or greater, 25°C or greater, 30°C or greater, 35°C or greater, 40°C or greater, 45°C or greater, or 50°C or greater. g In embodiments, the cured composition may have a T of 0°C to 100°C. g .

[0278] In some embodiments, the cured composition does not include a tertiary amine synergist.

[0279] In an embodiment, the cured composition does not include a small molecule photoinitiator (ie, a non-polymeric photoinitiator).

[0280] In an embodiment, the composition is photocured by irradiating the composition with a Phoseon LED 395 nm bulb. In other embodiments, the composition is photocured by irradiating the composition with a LC6 Fusion, H bulb.

[0281] In some embodiments, at least one (meth)acrylate oligomer is included and selected from at least one of urethane acrylate and urethane methacrylate, and at least one (meth)acrylate monomer is included and selected from at least one of 2-hydroxyethyl methacrylate and isobornyl methacrylate.

[0282] The acrylic copolymers described herein can be incorporated into a method for coating a substrate. In an embodiment, the method for coating a substrate comprises applying a composition to a substrate to form an uncured coating of the composition on the substrate, the composition comprising: an acrylic copolymer according to an embodiment described herein; and a reactive diluent (preferably at least one (meth)acrylate monomer); and exposing the uncured coating to UV radiation to cure the composition and obtain a cured coating on the substrate. Examples of substrates that can be coated include, but are not limited to, glass, polycarbonate, PET, polyethylene, polypropylene, metal, human and synthetic nails, paper and products including cardboard and paperboard, and ceramics.

[0283] Acrylic copolymers according to embodiments described herein are useful in graphics, ink, and industrial coating applications for which yellowing of the acrylic copolymer, cured compositions prepared from the acrylic copolymer, or coatings comprising the acrylic copolymer and applied to a substrate may be undesirable.

[0284] Example

[0285] The following examples are illustrative in nature and should not be construed as limiting the subject matter of the present disclosure.Using the above embodiments, exemplary reactive acrylic copolymers were prepared and used according to the following examples.

[0286] Material

[0287] 2-Carboxymethylthioxanthone (CMTX), 4-acryloxybenzophenone, methyl ethyl ketone (MEK), butyl acrylate (BA), tert-butyl acrylate, glycidyl methacrylate (GMA), methyl methacrylate (MMA), acetic acid, and hydroxyethylethylene urea methacrylate were purchased from Sigma Aldrich Chemical Company. Urethane methacrylate (UMA, CN1968®), urethane acrylate (UA, CN963®), hydroxyethyl methacrylate (HEMA, SR170®), and isobornyl methacrylate (IBOMA, SR423A®), ditrimethylolpropane tetraacrylate (DMPTA, SR355®), 2-isothioxanthone (ITX, Speedcure ITX®), and 2-ethylhexyl 4-(dimethylamino)benzoate (EHDMA, Speedcure EHA®) are common UV-curable monomers and photoinitiators developed by Sartomer.

[0288] Preparation of curable compositions

[0289] All curable compositions were prepared by adding the components to a Flacktek® polypropylene cup and mixing using a Flacktek® DAC 400.2 VAC high speed mixer at 1500-2000 rpm for 2 minutes until homogeneous.

[0290] Testing Procedure

[0291] In order to measure gel content, the following procedure was adopted. The sample was sucked onto a clean glass sheet with a pipette, and a 3 MIL coating was formed using a ByK draw-down square. The draw-down thickness used depends on the final methyl ethyl ketone (MEK) percentage in the reactive acrylic copolymer. For example, reactive acrylic copolymer 1 (RAC 1) was draw-downed with a four MIL thickness to obtain a three MIL coating of RAC 1 after MEK evaporation. After draw-down, the glass sheet was put into a 60 ℃ baking oven for 1 hour to remove the solvent. In order to solidify, the glass sheet was passed through 3 times at 15 feet / minute under a LC6 Fusion H bulb curing unit. For the gel content carried out in nitrogen, the glass sheet was put into a nitrogen chamber, and flushed with nitrogen for 10 minutes, and then the chamber was passed under a H bulb to solidify. After solidification, the cross-linked reactive acrylic copolymer film was removed from the glass sheet. Its initial weight was recorded, and the sample removed was immersed in MEK for 24 hours subsequently. To determine the final weight of the cross-linked reactive acrylic copolymer, the sample was vacuum filtered from the MEK and then placed in a 60°C oven to evaporate the excess MEK.

[0292] For optical differential scanning calorimetry experiment, the following procedure is adopted.In order to prepare the sample, the initial weight ratio of RAC 1 and ditrimethylolpropane tetraacrylate (DMPTA, SR355®) monomer is added to the Flacktek mixing cup, and the DAC 400.2 VAC high-speed mixer is used to mix for 2 minutes at 2000 RPM.A small amount of sample (5-10mg) is put into the aluminum Tzero dish, and then it is put into the baking oven at 60 ℃ for 1-2 hours to remove any residual solvent.The initial ratio of RAC 1: ditrimethylolpropane tetraacrylate is selected to realize the 1:1 weight ratio of RAC 1: ditrimethylolpropane tetraacrylate after flashing off the solvent.The sample is put into the TA instrument Q2000 DSC, which is equipped with EFOS A4000Acticure UV / visible light curing system, which contains a 100W mercury lamp light source and a reference dish. Prior to the experiment, the UV light intensity outside the sample window was measured using an EIT UV power puck II radiometer. During the experiment, the temperature was stabilized at 25°C. After one minute of equilibration, the UV light (broad spectrum) was turned on and the heat flow generated from the sample was recorded for two minutes. The light was turned off and the experiment was allowed to run for an additional minute to allow the heat flow to drop to the baseline. The total duration of the experiment was four minutes.

[0293] For UV curable coating compositions, the following procedure is used. In order to prepare UV / LED curable coating compositions, the sample is pipetted onto a clean glass sheet (4 inches x 4 inches). The sample is scraped onto the glass using a ByK 3 Mil scraping rod. The coating is placed in a 60°C baking oven for 1 hour to remove MEK. After MEK evaporates, all coatings are ~3MIL wet thickness. After drying, the coating is passed through (1) an LC6 Fusion H bulb curing unit three times (at 15 feet per minute), or (2) a Phoseon LED 395 nm bulb, 3 times, 30 fpm, to crosslink the coating composition. After curing, the initial color, haze, and yellowness are measured on a Hunter Lab ColorQuest XE spectrometer. Specifically, a Hunter Lab colorimeter is typically used to measure color, haze, and yellowness for liquid resins, and is measured by the ASTM D1209 APHA / Pt-Co color scale according to the ASTM D5386 method of the instrument. The method was modified to measure color, haze and yellowness of the coating through glass using the modified method. Hunter Lab ColorQuest XE spectrometer. Other performance properties were also measured, such as surface tack, Konig hardness and adhesion. ASTM D4366 was used to measure the Konig hardness of the coating formulation. Surface tack was qualitatively determined by assigning numbers from a subjective scale from 0 to 5 (0 is no tack / 5 is very tack). Adhesion tests were measured using ASTM 3359 Method B.

[0294] Example 1

[0295] Preparation of PA 1

[0296] The preparation of photoinitiator adduct 1 (PA 1) was achieved essentially as shown in Scheme 1:

[0297]

[0298] Scheme I

[0299] In brief, a round-bottom flask equipped with an agitator, a thermocouple, a heating jacket, a side arm and a condenser is loaded with glycidyl methacrylate (GMA), an inhibitor and a solvent. The device is heated to 110°C. 2-carboxymethoxythioxanthone (CMTX) is slowly added while the heating reaction is carried out. After the addition of CMTX is completed, air is passed into the mixture, and then heated at 110°C for 30 minutes to completely dissolve CMTX. The reaction mixture is cooled to less than 50°C, a catalyst is added, and then heated to 85°C. The reaction mixture is maintained at 85°C until the reaction is complete (determined by acid value and residual GMA by GC external standard method).

[0300] Example 2

[0301] Preparation of RAC 1

[0302] PA 1 was further reacted with butyl acrylate (BA) and methyl methacrylate (MMA) in methyl ethyl ketone (MEK) to form reactive acrylic copolymer 1 (RAC 1). Table 1 lists the ratios of the components in RAC 1 as well as the remaining solvent percentage in the final product, the predicted T g and molecular weight.

[0303] Acrylic copolymers are obtained by solution polymerization of the monomers shown in Table 1 using MEK in the amount shown in Table 1 as solvent. Solvent and monomer are added to 60 mL vials. Vazo52 initiator solution in solvent is prepared in a separate vial and then added to the monomer solution (total monomer: initiator weight ratio is 400: 1). The vial is then placed in a water bath at 65°C and shaken gently for 11 hours. Experimental conditions well known to those skilled in the art can be used to adjust solvent type, solid content, reaction temperature, reaction time and initiator: monomer ratio to produce acrylic copolymers of various molecular weights. Monomers between 100: 1 and 1000: 1: Vazo52 ratios are typically used to produce relatively low molecular weight acrylic copolymers, as described and used in the following examples.

[0304] surface .RAC 1 components

[0305]

[0306] Example 3

[0307] Curing properties of RAC 1

[0308] Further experiments show that RAC 1 demonstrates low self-reactivity. Specifically, after MEK evaporates and in air and nitrogen, using Fusion H bulb to solidify RAC 1 by 3 times at 15 feet per minute, RAC 1 still remains as liquid, which shows that three times are not enough to make the system light crosslink and form gel. Carry out the second attempt to solidify RAC 1, by making it pass through 10 times in total at 15 feet per minute under Fusion H bulb, to obtain gel-like consistency. It is found that the gel content of RAC 1 is lower than 10% (referring to Tables 2 and 3, entry 1). In order to attempt to improve curing speed and promote crosslinking, 4-(dimethylamino)benzoic acid 2-ethylhexyl ester (EHDMA, Speedcure EHA®) is added to RAC 1 with 3%. For RAC 1+3% EHDMA, gel content remains on less than 10%, and formulation still must pass through 10 times under lamp to fully solidify (referring to Tables 2 and 3, entry 2). Finally, the multifunctional monomer ditrimethylolpropane tetraacrylate (DMPTA, SR355®) was added to the formulation. With DMPTA, the formulations cured in three passes under Fusion and had high gel content, regardless of whether EHDMA was added (see Tables 2 and 3, entries 3 and 4).

[0309] surface . Gel content of the composition including RAC 1 after curing in air %

[0310]

[0311] surface . Gel content of the composition including RAC 1 after curing in nitrogen %

[0312]

[0313] The cure speed and reaction enthalpy of RAC 1 + 3% EHDMA, 1:1 DMPTA:RAC 1 and 1:1 DMPTA:RAC 1 + 3% EHDMA were measured (see Table 4). RAC 1 + 3% EHDMA cured the slowest. This result is consistent with RAC 1 having a low gel content. Due to the inclusion of monomer, 1:1 DMPTA:RAC 1 has a very fast cure time (0.16 minutes). Adding 3% EHDMA to the 1:1 DMPTA:RAC 1 formulation further increased the cure speed (0.04 minutes). The RAC 1 system with DMPTA exhibited similar heat generation during cure, while RAC 1 + 3% EHDMA exhibited lower heat generation.

[0314] surface Reaction enthalpy and curing rate in compositions including RAC 1 in air

[0315]

[0316] The above results indicate that RAC 1 can function as a polymeric photoinitiator in the presence of other acrylate-functional monomers, but it exhibits little self-reactivity.

[0317] Example 4

[0318] Cured composition comprising RAC 1 and (meth)acrylate monomer

[0319] RAC 1 was tested in different curable compositions. Under two different weight percentages (11.2% RAC 1 or 28% RAC 1), each composition included urethane methacrylate (UMA, CN1968®) or urethane acrylate (UA, CN963®), together with hydroxyethyl methacrylate (HEMA, SR170®) and isobornyl methacrylate (IBOMA, SR423A®). Based on RAC 1 having 1.7% chromophores loaded on the main chain, and considering that 30% MEK in RAC 1 will eventually be removed when drying, two different weight percentages provide 0.14% or 0.37% chromophore activity. Compositions are shown in Table 5, and are represented as Invention 1 (I1), Invention 2 (I2), Invention 3 (I3) and Invention 4 (I4). For comparison, a small molecule photoinitiator based on 2-isothioxanthone (ITX, Speedcure ITX®) was used with a similar amount of MEK and the same monomer mixture. The comparative compositions are shown in Table 5 and are denoted as Comparative 1 (C1), Comparative 2 (C2), Comparative 3 (C3) and Comparative 4 (C4).

[0320] surface . Curable composition comprising RAC 1 or ITX as a photoinitiator

[0321]

[0322] For each curable composition, two samples were taken. One sample was cured under a Fusion H bulb and the other sample was cured under a Phoseon LED 395 nm. The performance properties of the cured compositions are shown in Table 6 (Fusion H bulb cured) and Table 7 (Phoseon LED 395 nm cured).

[0323] Referring to the composition cured by the LC6 Fusion H bulb (Table 6), the initial color of the film after light curing of the comparative compositions C1, C2, C3 and C4 was shown to be greater than 100 (APHA, 10 mm), compared to less than 50 for each of the compositions I1, I2, I3 and I4 of the present invention. The initial yellowness (b ) values ​​are all greater than 4, while all compositions of the present invention are less than 1.2.

[0324] Referring to the composition cured by Phoseon LED 395 nm (Table 7), the initial color of the film after photocuring of the comparative compositions C1, C2, C3 and C4 was greater than 55 (APHA, 10 mm), compared to less than 7 for each of the compositions I1, I2, I3 and I4 of the present invention. The initial yellowness (b ) values ​​are all greater than 4, while all compositions of the present invention are less than 0.5.

[0325] The haze values ​​for both the compositions cured with LC6 Fusion H bulbs and Phoseon LED 395 nm after curing were higher for the low concentration compositions of the invention, which may be due to the interaction of the acrylic backbone with the urethane (meth)acrylate oligomers, which may indicate a small degree of incompatibility. The haze values ​​were significantly lower for the compositions containing higher concentrations of RAC1, which may be due to better compatibility with the matrix as the concentration increases. Due to the low T of the backbone g Properties, adhesion was improved at higher concentrations of RAC 1. For the LC6 Fusion H bulb cured compositions, surface tack was low for the UA formulations and surface hardness was high, indicating that the system was fully cross-linked.

[0326] surface Properties of cured compositions (LC6 Fusion H bulb cured) including RAC 1 or ITX as photoinitiator

[0327]

[0328] surface Properties of cured compositions (Phoseon LED 395 nm cured) including RAC 1 or ITX as photoinitiator

[0329]

[0330] To further illustrate why the cured composition comprising RAC 1 exhibits significantly lower yellowing than the cured composition comprising ITX, further comparative compositions were prepared. In particular, a curable composition comprising CMTX and PA 1 as a small molecule photoinitiator was prepared with a mixture of the same monomers as the above composition. Two different weight percentages provided an active amount of 0.2% or 0.5% of the chromophore. MEK was left in the system to evaporate, similar to the above-mentioned composition of the present invention. The comparative compositions are shown in Table 8 and are represented as Comparative 5 (C5), Comparative 6 (C6), Comparative 7 (C7), Comparative 8 (C8), Comparative 9 (C9), Comparative 10 (C10), Comparative 11 (C11) and Comparative 12 (C12).

[0331] surface .Curable composition comprising CMTX or PA 1 as a photoinitiator

[0332]

[0333] The compositions were cured with Fusion H bulbs, and the performance properties of the resulting cured compositions are shown in Table 9. After photocuring all C5-C12, the initial color of the film was again shown to be significantly greater than 100 (APHA, 10 mm), compared to less than 50 for each of the inventive compositions. The initial yellowness (b) of the film after photocuring for all comparative compositions was less than 1.2, compared to less than 1.3 for the inventive compositions. ) values ​​were all greater than 6. Similar to the previous compositions, the surface tack was low and the surface hardness was high for the UA formulation, indicating that the system was fully cross-linked.

[0334] surface Properties of cured compositions (LC6 Fusion H bulbs) including CMTX or PA 1 as photoinitiator

[0335]

[0336] A further comparative curable composition was prepared which included both the small molecule PA 1 together with a non-reactive acrylic copolymer having the same backbone components as RAC 1 but without the PA 1 moiety attached to the backbone. This control was tested to see if the acrylic copolymer backbone played a role in the low initial yellowing. The comparative compositions (prepared with the same mixture of monomers as the above compositions) are shown in Table 10 and are identified as Comparative 13 (C13), Comparative 14 (C14), Comparative 15 (C15), and Comparative 16 (C16).

[0337] surface . A curable composition comprising PA 1 and a non-reactive acrylic copolymer.

[0338]

[0339] The curable compositions were cured by Fusion H bulbs, and the performance properties of the resulting cured compositions are shown in Table 11. The performance properties of the coating compositions containing PA 1 together with a non-reactive acrylic copolymer are shown in Table 11. After photocuring of all C13-C16, the initial color of the film was again shown to be significantly greater than 100 (APHA, 10 mm), compared to less than 50 for each of the compositions of the present invention. The initial yellowness (b 20 mm) of the film after photocuring for all comparative compositions was less than 1.2, compared to less than 1.3 for the compositions of the present invention. ) values ​​are again greater than 6.

[0340] surface Properties of cured compositions (LC6 Fusion H bulbs) comprising PA 1 or non-reactive acrylic copolymers

[0341]

[0342] The UMA compositions appear to have lower initial yellowing than the UA compositions. This may be due to the different polyol backbones of each urethane (meth)acrylate oligomer. The UMA backbone has polyols that have the ability to undergo hydrogen abstraction more easily than the polyols in the UA backbone. Also, the initial yellowing is elevated in C13 and C15 compared to the compositions of the present invention, indicating that the use of RAC 1 as a photoinitiator provides lower yellowing than the combination of PA 1 and a non-reactive acrylic copolymer. Without wishing to be bound by theory, it is believed that having the PA 1 moiety attached to the backbone of RAC 1 reduces the probability of dimerization of the PA 1 moiety, which is a source of yellowing.

[0343] aspect

[0344] Further aspects of the invention are provided by the subject matter of the following clauses:

[0345] Item 1. An acrylic copolymer comprising the reaction product of: having a glass transition temperature (T) equal to or greater than 25°C g ) g Monomer, with a T less than 25°C g Low T g Monomer, or having a glass transition temperature (T) equal to or greater than 25°C g ) g monomer and having a T less than 25°C g Low T g A combination of monomers; a chromophore monomer comprising a moiety selected from thioxanthone, anthraquinone, or camphorquinone; and optionally additional monomers.

[0346] Item 2. The acrylic copolymer according to Item 1, wherein the oligomer has formula (I)

[0347] (I)

[0348] in:

[0349] - Each A 1 Independently (C1-C 30 )alkyl or (C1-C 30 ) heteroalkyl, preferably (C1-C 30 ) alkyl;

[0350] - Each A 2 Independently (C4-C 30 )alkyl or (C4-C 30 ) heteroalkyl, preferably (C4-C 30 ) alkyl;

[0351] - Each A 3 are independently a residue comprising a monovalent group comprising a moiety selected from thioxanthone, anthraquinone or camphorquinone, preferably thioxanthone.

[0352] - Each A 4 Independently (C1-C 30 )alkyl or (C1-C 30 ) heteroalkyl;

[0353] -Z 1 , Z 2 , Z 3 and Z 4 Independently -H or (C1-C4) alkyl, preferably -H or -CH3;

[0354] -m means high T g The weight fraction of the monomer is 0 to 0.999;

[0355] -n is low T g The weight fraction of the monomer is 0 to 0.999;

[0356] -p is the weight fraction of the chromophore monomer and is 0.001 to 0.4;

[0357] -q is the weight fraction of the additional monomer and is from 0 to 0.2;

[0358] -m+n is greater than or equal to 0.4; and

[0359] -m+n+p+q=1.

[0360] Item 3. The acrylic copolymer according to Item 2, wherein: m is from 0.001 to 0.999, preferably from 0.01 to 0.50; and n is from 0.001 to 0.999, preferably from 0.50 to 0.98; and m+n is greater than or equal to 0.6.

[0361] Item 4. The acrylic copolymer according to Item 2 or 3, wherein Z 1 Methyl, A 1 is methyl, and A 2 It is n-butyl.

[0362] Item 5. The acrylic copolymer according to any one of Items 2 to 4, wherein A 3 It is a monovalent group containing a thioxanthone moiety.

[0363] Item 6. The acrylic copolymer according to any one of Items 2 to 5, wherein A 3 Having formula (IVa) or (IVb):

[0364] (IVa)

[0365] (IVb)

[0366] in:

[0367] L 1 is an alkylene group;

[0368] L 2 is a divalent linker comprising at least 2 carbon atoms;

[0369] R 1 and R 2 each independently selected from -H, halogen, alkyl, cycloalkyl, heterocycloalkyl, alkoxy, aryloxy, sulfanyl, sulfaryl, alkenyl, alkynyl, aryl, aralkyl, alkaryl, heteroaryl, -C(=O)R a 、-NR b R c 、alkylamino、alkylthiol、halogenated alkyl、-NO2、-CN、-C(=O)OR d 、-C(=O)NR b R c ;

[0370] R a is selected from optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted heterocycloalkyl, and optionally substituted aryl;

[0371] R b , R c and R d are independently selected from -H, alkyl and aryl.

[0372] Item 7. The acrylic copolymer according to any one of items 2 to 6, wherein q is 0.

[0373] Clause 8. The acrylic copolymer according to any one of the preceding clauses, wherein A 1 Methyl, A 2 is n-butyl, and A 3 Having formula (IVc) or (IVd):

[0374] (IVc)

[0375] (IVd)

[0376] Wherein h is 1 to 20.

[0377] Clause 9. The acrylic copolymer according to any one of the preceding clauses, wherein Z 1 is methyl, Z 2 is -H, and Z 3 is -H.

[0378] Clause 10. The acrylic copolymer according to any of the preceding clauses, wherein q is not equal to zero and the at least one additional monomer comprises at least one amine synergistic monomer.

[0379] Item 11. The acrylic copolymer according to any one of the preceding items, comprising a high T g Monomer and Low T g Monomer, among which high T g Fox equation average T of monomer g T g Fox equation average T of monomer g At least 20°C higher.

[0380] Item 12. An acrylic copolymer according to any one of the preceding items, comprising a high T g Monomer and Low T g Monomer, among which high T g Fox equation average T of monomer unit g and low T g Fox equation average T of monomer unit g The difference is between 20°C and 200°C.

[0381] Item 13. An acrylic copolymer according to any one of the preceding items, comprising at least two unrelated types of high T g monomer.

[0382] Item 14. An acrylic copolymer according to any one of the preceding items, comprising at least two unrelated types of low T g monomer.

[0383] Item 15. An acrylic copolymer according to any one of the preceding items, comprising a high T g Monomer and Low T g Monomers, including low T in acrylic copolymers g Monomer and high T g The weight ratio of the monomer units is 10:1 to 1:9.

[0384] Item 16. The acrylic copolymer according to any one of the preceding items, comprising at least one high T selected from the following g Monomers: 2-phenylethyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, tert-butyl acrylate, octadecyl methacrylate, octadecyl acrylate, propyl methacrylate, benzyl methacrylate, isobutyl methacrylate, ethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 2,2,2-trifluoroethyl methacrylate, isopropyl methacrylate, isobornyl acrylate, methyl methacrylate, isobornyl methacrylate, phenyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, 4-tert-butylcyclohexyl acrylate, 4-tert-butylcyclohexyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, substituted or unsubstituted (meth)acrylic acid (C6-C 12 )cycloalkyl ester, adamantyl (meth)acrylate, tricyclodecanemethanol mono(meth)acrylate, or a combination thereof.

[0385] Clause 17. The acrylic copolymer according to any of the preceding clauses, comprising at least one low T selected from the following g Monomer: n-butyl (meth)acrylate, isobutyl acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, nonyl acrylate, decyl (meth)acrylate, octyl (meth)acrylate, propyl acrylate, isobutyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, ethyl acrylate, sec-butyl acrylate, dodecyl acrylate, tetradecyl (meth)acrylate, isopropyl acrylate, amyl (meth)acrylate, benzyl acrylate, cyclohexyl acrylate, hexadecyl (meth)acrylate, 2-methylbutyl acrylate, 2-octyl acrylate or a combination thereof.

[0386] Item 18. The acrylic copolymer according to any one of the preceding items, comprising at least one chromophore monomer according to formula (IVe) or (IVf).

[0387] (IVe)

[0388] (IVf)

[0389] Wherein h is 1 to 10.

[0390] Item 19. An acrylic copolymer according to any of the preceding items, comprising at least one additional monomer selected from the group consisting of caprolactone-extended acrylates (SR49B, Sartomer), cyclic trimethylolpropane formal acrylate (SR531, Sartomer), propoxylated tetrahydrofurfuryl acrylate (SR611, Sartomer), β-carboxyethyl acrylate, glycidyl methacrylate, or 2-(2-ethoxyethoxy)ethyl acrylate (SR256), neopentyl monomethacrylate, tetrahydrofurfuryl (meth)acrylate, phenoxyethyl acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-cyanobutyl acrylate, 4-cyanobutyl acrylate, 2-cyanoethyl acrylate, cyanomethyl acrylate, and combinations thereof.

[0391] Clause 20. An acrylic copolymer according to any of the preceding clauses, comprising at least one additional monomer selected from the group consisting of (meth)acrylic acid, dimethylaminoethyl acrylate (DMAEA), dimethylaminoethyl methacrylate (DMAEMA), diethylaminoethyl acrylate (DEAEA), diethylaminoethyl methacrylate (DEAEMA), N-vinyl pyrrolidone (NVP), N-vinyl caprolactam (VCAP), acryloxymorpholine (ACMO), dimethylacrylamide (DMAC), poly(ethylene oxide) mono(meth)acrylate, hydroxyethylethylene urea (meth)acrylate (HEEU(M)A), reaction products of cyclic anhydrides and hydroxy-functional (meth)acrylates, and combinations thereof.

[0392] Item 21. The acrylic copolymer according to any of the preceding items, comprising at least one additional monomer selected from the group consisting of aminobenzoates, polymerizable aminobenzoates, polymeric aminobenzoates, and mixtures thereof.

[0393] Clause 22. The acrylic copolymer according to any one of the preceding clauses, wherein the acrylic copolymer has a glass transition temperature T of equal to or less than -10°C. g .

[0394] Item 23. A curable composition comprising an acrylic copolymer according to any preceding item and one or more of the following compounds: (meth)acrylate monomers, diluents, (meth)acrylate oligomers, amine synergists, fillers, photoinitiators, slip agents, thickeners, slip agents, hindered amine light stabilizers, UV absorbing monomers or other auxiliary additives.

[0395] Clause 24. The curable composition of Clause 23, wherein the curable composition comprises a reactive diluent.

[0396] Clause 25. The curable composition according to Clause 24, wherein the reactive diluent comprises a polyol having a T greater than 25°C. g The monofunctional (meth)acrylate monomer is selected from the group consisting of 2-phenylethyl methacrylate, neopentyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, tert-butyl acrylate, octadecyl methacrylate, octadecyl acrylate, glycidyl methacrylate, propyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, isobutyl methacrylate, glycidyl methacrylate, ethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 2-hydroxypropyl methacrylate, 2,2,2- trifluoroethyl ester, 2-hydroxyethyl methacrylate, isopropyl methacrylate, isobornyl acrylate, methyl methacrylate, butyl cyanoacrylate, isobornyl methacrylate, phenyl methacrylate, 2-cyanobutyl acrylate, tert-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 4-tert-butylcyclohexyl acrylate, 4-tert-butylcyclohexyl methacrylate, ethyl cyanoacrylate, methyl cyanoacrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, substituted or unsubstituted (meth)acrylic acid (C6-C 12 )cycloalkyl ester, adamantyl (meth)acrylate, dicyclopentyl (meth)acrylate, tricyclodecanemethanol mono(meth)acrylate, 2-phenoxyethyl methacrylate, or a combination thereof.

[0397] Clause 26. A curable composition according to clause 24 or 25, wherein the reactive diluent comprises a multifunctional (meth)acrylate, in particular a multifunctional (meth)acrylate selected from the group consisting of 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. di(meth)acrylate of 1,5-pentanediol; di(meth)acrylate of 1,6-hexanediol; di(meth)acrylate of 1,8-octanediol; di(meth)acrylate of 1,9-nonanediol; di(meth)acrylate of 1,10-nonanediol; di(meth)acrylate of 1,12- Dodecanediol di(meth)acrylate; neopentyl glycol di(meth)acrylate; 2-methyl-2,4-pentanediol di(meth)acrylate; polybutadiene di(meth)acrylate; cyclohexane-1,4-dimethanol di(meth)acrylate; tricyclodecane dimethanol di(meth)acrylate; metal di(meth)acrylate; modified metal di(meth)acrylate; glyceryl di(meth)acrylate; glyceryl 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; pentaerythritol tetra(meth)acrylate, di(trimethylolpropane) diacrylate; di(trimethylolpropane) triacrylate; di(trimethylolpropane) tetraacrylate, sorbitol penta(meth)acrylate; di(pentaerythritol) tetraacrylate; di(pentaerythritol) pentaacrylate; di(pentaerythritol) hexa(meth)acrylate; tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate; and alkoxylated (e.g., ethoxylated and / or propoxylated) derivatives thereof; and combinations thereof.

[0398] Item 27. A curable composition according to any one of items 24 to 26, wherein the curable composition is substantially free of photoinitiators other than the acrylic copolymer according to any one of items 1 to 22, in particular, the curable composition contains less than 0.1 wt %, in particular less than 0.05 wt %, more in particular less than 0.001 wt %, even more in particular 0 wt % of photoinitiators other than the acrylic copolymer according to any one of items 1 to 22.

[0399] Clause 28. The curable composition of any one of Clauses 24 to 27, wherein the curable composition comprises an amine synergist.

[0400] Clause 28. The curable composition of any one of Clauses 24 to 27, wherein the curable composition is substantially free of amine synergists.

[0401] Item 29. A cured composition which is the product of photocuring a composition comprising: an acrylic copolymer according to any one of Items 1 to 22; and a reactive diluent (preferably at least one (meth)acrylate monomer) or at least one (meth)acrylate oligomer, or both; wherein the cured composition exhibits: an APHA-10mm initial color of 0.1 to 50; an initial yellowness (b ); and a T equal to or greater than 0°C g .

[0402] Clause 30. The cured composition of Clause 29, wherein the cured composition exhibits an APHA-10 mm initial color of 0.1 to 40.

[0403] Clause 31. A cured composition according to Clause 29 or 30, wherein the cured composition exhibits an initial yellowness (b yellowness) of 0.01 to 1.2. ).

[0404] Clause 32. The cured composition of any one of Clauses 29 to 31, wherein the composition does not comprise a tertiary amine synergist.

[0405] Clause 33. The cured composition of any one of Clauses 29 to 32, wherein the composition does not comprise a small molecule photoinitiator.

[0406] Clause 34. A cured composition according to any one of Clauses 29 to 33, wherein the at least one (meth)acrylate oligomer is included and is selected from at least one of urethane acrylates and urethane methacrylates, and the at least one (meth)acrylate monomer is included and is selected from at least one of 2-hydroxyethyl methacrylate and isobornyl methacrylate.

[0407] Clause 35. The cured composition of any of Clauses 29 to 34, wherein the acrylic copolymer has a weight average molecular weight of at least 10,000 g / mol.

[0408] Item 36. A method of coating a substrate, the method comprising: applying a composition to a substrate to form an uncured coating of the composition on the substrate, the composition comprising: an acrylic copolymer according to any one of items 1 to 22; and a reactive diluent, preferably at least one (meth)acrylate monomer; and exposing the uncured coating to UV radiation to cure the composition and obtain a cured coating on the substrate.

[0409] Clause 37. The method of Clause 36, wherein the substrate is selected from glass, polycarbonate, PET, polyethylene, polypropylene, metal, human and synthetic nails, paper and products including cardboard and paperboard, and ceramics.

[0410] It will be apparent to those skilled in the art that various modifications and variations may be made without departing from the scope disclosed herein. Since those skilled in the art may conceive of modifications, combinations, sub-combinations and variations of the disclosed embodiments, which incorporate the spirit and substance disclosed herein, the scope disclosed herein should be interpreted as including all contents within the scope of the appended claims and their equivalents.

[0411] For the purpose of defining the present technology, the transitional phrase "consisting of" may be introduced into a claim as a closed preamble term to limit the scope of the claim to the listed components or steps and any naturally occurring impurities. For the purpose of defining the present technology, the transitional phrase "consisting essentially of" may be introduced into a claim to limit the scope of one or more claims to the listed elements, components, materials, or method steps and any unlisted elements, components, materials, or method steps that do not materially affect the novel characteristics of the claimed subject matter.

[0412] As used in the specification and the appended claims, the singular forms "a, an," "a, an," and "the" include plural references unless the context clearly dictates otherwise. The verb "comprise" and its conjugated forms should be interpreted as referring to elements, components, or steps in a non-exclusive manner. The referenced elements, components, or steps may be present, used, or combined with other elements, components, or steps that are not explicitly referenced.

[0413] It should be understood that any two values ​​assigned to a property may constitute a range for that property, and the present disclosure contemplates all combinations of ranges formed by all said values ​​for a given property. The subject matter disclosed herein has been described in detail by specific embodiments. It should be understood that any detailed description of a component or feature of an embodiment does not necessarily mean that the component or feature is essential to a particular embodiment or any other embodiment.

Claims

1. An acrylic copolymer comprising the reaction product of: Having a glass transition temperature (T) equal to or greater than 25°C g ) g Monomer, with a T less than 25°C g Low T g Monomer, or having a glass transition temperature (T) equal to or greater than 25°C g ) g monomer and having a T less than 25°C g Low T g Combination of monomers; a chromophore monomer comprising a moiety selected from thioxanthone, anthraquinone, or camphorquinone; and Optionally at least one additional monomer.

2. The acrylic copolymer according to claim 1, wherein the acrylic copolymer has formula (I): (I) in: - Each A 1 Independently (C1-C 30 ) alkyl or (C1-C 30 ) heteroalkyl, preferably (C1-C 30 ) alkyl; - Each A 2 Independently (C4-C 30 )alkyl or (C4-C 30 ) heteroalkyl, preferably (C4-C 30 ) alkyl; - Each A 3 are independently a residue comprising a monovalent group comprising a moiety selected from thioxanthone, anthraquinone or camphorquinone, preferably thioxanthone; - Each A 4 Independently (C1-C 30 ) alkyl or (C1-C 30 ) heteroalkyl; -Z 1 , Z 2 , Z 3 and Z 4 Independently -H or (C1-C4) alkyl, preferably -H or -CH3; -m is the high T g The weight fraction of the monomer is 0 to 0.999; -n is the low T g The weight fraction of the monomer is 0 to 0.999; -p is the weight fraction of the chromophore monomer and is 0.001 to 0.4; -q is the weight fraction of the additional monomer and is 0 to 0.2; -m+n is greater than or equal to 0.4; and -m+n+p+q=1.

3. The acrylic copolymer according to claim 2, wherein: m is 0.001 to 0.999, preferably 0.01 to 0.50; and n is 0.001 to 0.999, preferably 0.50 to 0.98; m+n is greater than or equal to 0.

6.

4. The acrylic copolymer according to claim 2 or 3, wherein Z 1 Methyl, A 1 is methyl, and A 2 It is n-butyl.

5. The acrylic copolymer according to any one of claims 2 to 4, wherein A 3 It is a monovalent group containing thioxanthone.

6. The acrylic copolymer according to any one of claims 2 to 5, wherein A 3 Having formula (IVa) or (IVb): (II) (III) in, In Formula (IVa) and Formula (IVb): L 1 is an alkylene group; L 2 is a divalent linker comprising at least 2 carbon atoms; R 1 and R 2 each independently selected from -H, halogen, alkyl, cycloalkyl, heterocycloalkyl, alkoxy, aryloxy, sulfanyl, sulfaryl, alkenyl, alkynyl, aryl, aralkyl, alkaryl, heteroaryl, -C(=O)R a 、-NR b R c 、alkylamino、alkylthiol、halogenated alkyl、-NO2、-CN、-C(=O)OR d 、-C(=O)NR b R c ; R a is selected from optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted heterocycloalkyl, and optionally substituted aryl; and R b , R c and R d are independently selected from -H, alkyl and aryl. 7 . The acrylic copolymer according to claim 2 , wherein q is 0. 8 .

8. A curable composition comprising the acrylic copolymer according to any one of claims 1 to 7 and a reactive diluent.

9. The curable composition according to claim 8, wherein the reactive diluent comprises a polyol having a T greater than 25°C. g The monofunctional (meth)acrylate monomer is selected from the group consisting of 2-phenylethyl methacrylate, neopentyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, tert-butyl acrylate, octadecyl methacrylate, octadecyl acrylate, glycidyl methacrylate, propyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, isobutyl methacrylate, glycidyl methacrylate, ethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 2-hydroxypropyl methacrylate, 2,2,2- trifluoroethyl ester, 2-hydroxyethyl methacrylate, isopropyl methacrylate, isobornyl acrylate, methyl methacrylate, butyl cyanoacrylate, isobornyl methacrylate, phenyl methacrylate, 2-cyanobutyl acrylate, tert-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 4-tert-butylcyclohexyl acrylate, 4-tert-butylcyclohexyl methacrylate, ethyl cyanoacrylate, methyl cyanoacrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, substituted or unsubstituted (meth)acrylic acid (C6-C 12 )cycloalkyl ester, adamantyl (meth)acrylate, dicyclopentyl (meth)acrylate, tricyclodecanemethanol mono(meth)acrylate, 2-phenoxyethyl methacrylate, or a combination thereof.

10. The curable composition according to claim 8 or 9, wherein the reactive diluent comprises a multifunctional (meth)acrylate, in particular a multifunctional (meth)acrylate selected from the group consisting of 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. (Meth)acrylate; polypropylene glycol di(meth)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-nonanediol di(meth)acrylate; 1,12-decanediol di(meth)acrylate Dialkylene glycol di(meth)acrylate; neopentyl glycol di(meth)acrylate; 2-methyl-2,4-pentanediol di(meth)acrylate; polybutadiene di(meth)acrylate; cyclohexane-1,4-dimethanol di(meth)acrylate; tricyclodecane dimethanol di(meth)acrylate; metal di(meth)acrylate; modified metal di(meth)acrylate; glyceryl di(meth)acrylate; glyceryl 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; pentaerythritol tetra(meth)acrylate, di(trimethylolpropane) diacrylate; di(trimethylolpropane) triacrylate; di(trimethylolpropane) tetraacrylate, sorbitol penta(meth)acrylate; di(pentaerythritol) tetraacrylate; di(pentaerythritol) pentaacrylate; di(pentaerythritol) hexa(meth)acrylate; tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate; and alkoxylated (e.g., ethoxylated and / or propoxylated) derivatives thereof; and combinations thereof.

11. The curable composition according to any one of claims 8 to 10, wherein the curable composition is substantially free of photoinitiators other than the acrylic copolymer according to any one of claims 1 to 7, in particular, the curable composition comprises less than 0.1 wt%, in particular less than 0.05 wt%, more in particular less than 0.001 wt%, even more in particular 0 wt% of photoinitiators other than the acrylic copolymer according to any one of claims 1 to 7.

12. A method for preparing a curable composition according to any one of claims 8 to 11, wherein the method comprises the following steps: - preparing an acrylic copolymer as defined in any one of claims 1 to 7 dissolved in a non-reactive solvent; - adding a reactive diluent to obtain a diluted curable composition; - removing at least part of the non-reactive solvent from the diluted curable composition to obtain the curable composition.

13. A method of curing a curable composition according to any one of claims 8 to 11 or prepared by the method according to claim 12, wherein the method comprises curing the curable composition by irradiating the curable composition with a light source having a wavelength and / or intensity capable of activating the polymerized chromophore monomer units of the acrylic copolymer and causing crosslinking of the acrylic copolymer and / or the reactive diluent.

14. A cured composition which is the product of photocuring a composition comprising: The acrylic copolymer according to any one of claims 1 to 7; and a reactive diluent, preferably at least one (meth)acrylate monomer, or at least one (meth)acrylate oligomer, or both; wherein the cured composition exhibits: an APHA-10 mm initial color of 0.1 to 50; 0.01 to 2 initial yellowness (b ); and a T equal to or greater than 0°C g .

15. The cured composition of claim 14, wherein the cured composition exhibits an APHA-10 mm initial color of 0.1 to 40.

16. The cured composition according to claim 14 or 15, wherein the cured composition exhibits an initial yellowness (b yellowness) of 0.01 to 1.

2. ).

17. The cured composition of any one of claims 14 to 16, wherein the composition does not contain a tertiary amine synergist.

18. A cured composition according to any one of claims 14 to 17, wherein the composition does not contain a small molecule photoinitiator.

19. The cured composition according to any one of claims 14 to 18, wherein the at least one (meth)acrylate oligomer is included and is selected from at least one of urethane acrylates and urethane methacrylates, and the at least one (meth)acrylate monomer is included and is selected from at least one of 2-hydroxyethyl methacrylate and isobornyl methacrylate.

20. The cured composition of any one of claims 14 to 19, wherein the acrylic copolymer has a weight average molecular weight of at least 10,000 g / mol.

21. A method of coating a substrate, the method comprising: applying a composition to a substrate to form an uncured coating of the composition on the substrate, the composition comprising: The acrylic copolymer according to any one of claims 1 to 7; as well as a reactive diluent, preferably at least one (meth)acrylate monomer; and The uncured coating is exposed to UV radiation to cure the composition and obtain a cured coating on the substrate.

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