Liquid zinc acrylate complexes used in deinking process

Abstract

Curable compositions that include at least one liquid zinc (meth)acrylate complex, the complex comprising an ethylenically-unsaturated carboxylic acid ligand coordinated with zinc, are useful for forming primers, inks, and coatings on substrates that can undergo a triggered removal process using a water-based remover. Also, a method for recycling a substrate obtained by curing a curable primer, ink, or coating composition comprising the at least one liquid zinc (meth)acrylate complex by contacting the substrate coated with the cured primer, coating, or ink composition with a recycling solution having a pH sufficient to delaminate the cured primer, coating, or ink composition from the substrate.

Description

[0001] LIQUID ZINC ACRYLATE COMPLEXES USED IN DEINKING PROCESS

[0002] The present invention relates to curable compositions based on liquid zinc (meth)acrylate complexes, methods of using the compositions based on the liquid zinc (meth)acrylate complexes, and compositions and articles containing the compositions based on the liquid zinc (meth)acrylate complexes in cured form, especially for use in inks and coatings, to allow for easy removal of the cured inks and coatings once subjected to recycling, soaking, or delaminating conditions.

[0003] Background of the Invention

[0004] In view of the impacts of climate change and the increasing rate of consumption of our planet’s natural resources, there has been a growing desire in the chemical industry to ensure sustainable consumption and production patterns. In the market segment of curable inks and coatings, this desire manifests itself in developing technologies that would permit easy and substantially complete delamination of the inks and coatings from their substrates. Such technologies would allow for separate recycling or reuse of the substrates. Efforts have been made to permit such separation and recycling, including by Siegwerk, which has recently introduced sacrificial deinking primers for labels and sleeves.

[0005] Much literature that describes the removal of a paint coating or a pressure sensitive adhesive / laminating adhesive label discloses the use of either a low vapor pressure or caustic-type solvent, both of which are non-biodegradable, harmful to the environment, and potentially harmful to the person using the solvent. See, e.g., US2010008952A, W02010115564A1.

[0006] Summary of the Invention

[0007] In view of the prior art, an object of the invention was to prepare liquid zinc (meth)acrylate oligomers capable of deinking when formulated in graphic art printing inks cured onto plastic substrates. The liquid zinc (meth)acrylate can be used to formulate printable inks that upon UV curing have similar performance to other acrylate-based printable inks, but when placed under recyclable conditions of printed plastic films, liquid zinc (meth)acrylate containing ink, especially inkjet ink formulations, delaminate from the plastic substrate easily. The delamination of the printing ink is important to obtain clean plastic substrates that can be recycled and reintroduced in the consumable chain without needing any further chemical cleaning. An aspect of the invention is a method for recycling a substrate coated with a cured primer, coating, or ink composition, wherein the cured composition is obtained by curing a curable primer, ink, or coating composition comprising: at least one liquid zinc (meth)acrylate complex, the complex comprising a ligand coordinated with zinc; at least one polymerizing monomer and / or oligomer; and at least one initiator, the method comprising the steps of: contacting the substrate coated with the cured primer, coating, or ink composition with a recycling solution having a pH sufficient to delaminate the cured primer, coating, or ink composition from the substrate.

[0008] Another aspect of the invention is the method of the invention, wherein the ligand comprises at least one ethylenically unsaturated carboxylic acid.

[0009] Another aspect of the invention is the method of the invention, wherein the at least one ethylenically unsaturated carboxylic acid comprises a (meth)acrylate-functionalized carboxylic acid.

[0010] Another aspect of the invention is the method of the invention, wherein the at least one ethylenically unsaturated carboxylic acid comprises a half ester reaction product of a hydroxy-functionalized ethylenically unsaturated compound and a poly carboxylic acid or carboxylic acid anhydride.

[0011] Another aspect of the invention is the method of the invention, wherein the complex corresponds to Formula (I):

[0012] Zn(OC(=O)CR1=CH2)x(O-C(=O)-R2-C(=O)-O-R3O-C(=O)CR4=CH2)y(I) wherein x and y are independently 0, 1, or 2, x + y = 2, R1and R4are the same or different and are H or CH3, and R2and R3are the same or different and are divalent organic moieties each containing two or more carbon atoms.

[0013] Another aspect of the invention is the method of the invention, wherein the curable composition comprises a film or a coating composition, or wherein the curable composition comprises a primer or an ink composition, or wherein the curable composition comprises an inkjet formulation.

[0014] Another aspect of the invention is the method of the invention, wherein the cured composition comprises a cured film or coating, or wherein the cured composition comprises a cured primer or ink, or wherein the cured composition comprises a cured ink jet formulation.

[0015] Another aspect of the invention is the method of the invention, wherein delamination occurs within 10 minutes of exposure to the recycling solution.

[0016] Another aspect of the invention is the method of the invention, further comprising retrieving from the recycling solution the substrate substantially free from the cured primer, coating, or ink composition.

[0017] Another aspect of the invention is at least one liquid zinc (meth)acrylate complex, the complex comprising a ligand coordinated with zinc and comprising at least one ethylenically unsaturated carboxylic acid, wherein the zinc (meth)acrylate complex has an acid content of at least 5xl0'4mol acid / g complex, such as at least 5.25 xlO'4, such as at least 5.5xl0'4, preferably between 6 xlO'4and 9.5xl0'4, more preferably between 6.5xl0'4and 9.25xl0'4, more preferably between 7xl0'4and 9xl0'4and most preferably between 7.5xl0'4and 8.5xl0'4mol acid / g complex.

[0018] Brief Description of the Drawings

[0019] The following figures represent exemplary embodiments of the invention and are not intended to otherwise limit the description of the invention as described herein.

[0020] Figure 1 shows photographs of substrates coated with Formulations 1-3 or 1-4 of Example 1. Figure la corresponds to the substrate prior to contact with the recycling solution. Figure lb corresponds to the substrate after contact with the recycling solution.

[0021] Figure 2 shows photographs of substrates coated with the cured, pigmented inkjet formulation of Example 2. Figure 2a corresponds to the substrate prior to contact with the recycling solution. Figure 2b corresponds to the substrate after contact with the recycling solution. Detailed Description of the Invention

[0022] Definitions

[0023] As used herein “acid content” is calculated as the total acid content of a compound (in moles) before any neutralization of the acid groups has taken place (i.e., assuming 100% of the acid groups are in their free acid (non-salt) form) per gram of the curable liquid zinc (meth)acrylate complexes of the invention. When determining the acid content of a liquid zinc (meth)acrylate complex that has at least some of its acid groups neutralized or complexed with zinc, it is presumed for purposes of this calculation that 100% of the acid groups exist in their free acid, regardless of whether the base(s) is / are provided: (1) during the preparation of the complex, (2) after the complex has been prepared but before formulation with other constituents, (3) after the complex has been formulated with other constituents one of which includes a base, and / or (4) in a recycling or soaking solution after the complex has been prepared, formulated, and cured. So, a liquid zinc (meth)acrylate complex of the invention having a certain acid content encompasses such a complex that has none of the acid groups neutralized or at least some, including a majority and up to 100%, of its acid groups neutralized.

[0024] As used herein, “acid group” refers to any functionality present in the curable liquid zinc (meth)acrylate complexes of the invention that contains an acidic hydrogen atom and primarily refers to carboxylic acid groups, but also includes functional groups such as sulfonic acids, phosphoric acids, phosphonic acids and phosphinic acids.

[0025] As used herein, “aliphatic compound” or “aliphatic group” or “aliphatic linker” refers to a compound, group, or linker that is non-aromatic and acyclic, linear or branched, saturated or unsaturated, which may comprise one or more ether bonds, ester bonds, amide bonds, urethane bonds, urea bonds and mixtures thereof, and which may be substituted by one or more groups independently selected from, for example, alkyl, hydroxyl, halogen (F, Cl, Br, I), isocyanate, carbonyl, amine, carboxylic acid, -C(=O)-OR’ and -C(=O)-O- C(=O)-R’, with each R’ being independently a Ci-Ce alkyl.

[0026] As used herein, “cycloaliphatic compound” or “cycloaliphatic group” or “cycloaliphatic linker” refers to a compound, group or linker that is non-aromatic and cyclic, which may comprise one or more aliphatic bonds, and which may be substituted by one or more aliphatic groups. As used herein, “photosensitive composition” refers to a composition that reacts upon exposure to light, in particular UV, near-UV, visible, infrared or near-infrared light.

[0027] As used herein, “substantially the same wavelength” refers to a wavelength that is the same as another wavelength or is higher or lower than the other wavelength by no more than 10 nm, or 8 nm or 5 nm or 4 nm or 3 nm or 2 nm or 1 nm.

[0028] As used herein, “photoinitiator” refers to a compound that, upon irradiation with light (i.e. UV, near-UV, visible, infrared or near-infrared light) forms an initiating species (i.e. radicals and / or ions) that initiate the polymerization of a polymerizable monomer. A photoinitiator may be chemically changed after the polymerization as it has reacted with other chemical species.

[0029] As used herein, the term “light” refers to electromagnetic radiation in any appropriate region of the electromagnetic spectrum and is not limited to visible light. Accordingly, the term “light” encompasses UV, near-UV, visible, infrared or near-infrared electromagnetic radiation. As used herein, the term “irradiation” refers to light directed toward a surface, composition, molecule, etc., so that it contacts the surface, composition, molecule, etc.

[0030] As used herein, a “recycling solution” or a “soaking solution” refers to a solution that when contacted with a cured composition (such a film, coating, ink or primer) containing a curable liquid zinc (meth)acrylate complex of the invention results in the release or delamination of the cured composition from a substrate to which the composition is attached. While the release or delamination of the curable liquid zinc (meth)acrylate complex-containing composition from the substrate to which it is attached is typically complete and total, a partial release or partial delamination of the composition may also represent an acceptable or satisfactory outcome, depending on the particular technical area involved. In the case where delamination is only partial, manual means may be employed for removal of the portion of the coating / composition that remains attached to the substrate surface.

[0031] The term “polymer” as used herein is meant to include organic molecules with a number average molecular weight higher than 1,000 Da, or higher than 1,500 Da, or higher than 2,000 Da, or higher than 2,500 Da, or higher than or 5,000 Da, or higher than 50,000 Da as measured by gel permeation chromatography using tetrahydrofuran as solvent and polystyrene of known molecular weight as calibration standards. The term “(meth)acrylate” is understood to encompass either or both acrylate and methacrylate functional groups.

[0032] Curable Composition

[0033] The method of the present invention employs a substrate coated with a cured composition. The cured composition is obtained by curing a curable composition. The curable composition comprises, consists essentially of, or consists of: at least one liquid zinc (meth)acrylate complex, the complex comprising a ligand coordinated with zinc; at least one polymerizing monomer and / or oligomer; and at least one initiator.

[0034] The curable composition, may be a curable primer, ink, film, or coating composition. Accordingly, the present invention also relates to a curable composition (in particular a curable primer, ink, film, or coating composition) comprising the at least one liquid zinc (meth)acrylate complex as defined above.

[0035] The curable composition may be a curable primer, ink, film or coating composition comprising the at least one liquid zinc (meth)acrylate complex of the invention and a photoinitiator. Such compositions may particularly be used for forming a film on or coating at least part of the surface of a substrate, including a primer coating formed on a substrate, over which additional coating layers may be formed.

[0036] The curable composition may be an ink composition, including an inkjet formulation, comprising the at least one liquid zinc (meth)acrylate complex of the invention and optionally a photoinitiator. Such compositions may particularly be used to print an image or a text on at least part of a surface of a substrate.

[0037] Such compositions may be clear (such as a primer) or pigmented and are formulated to be usable as one-part systems, that is, formulations capable of being applied to a substrate surface and then cured by exposure to actinic radiation (e.g., UV or visible light). One or more additional components may additionally be present, in particular pigments and / or colorants and other monomers, oligomers, and / or polymers as described in more detail henceforth.

[0038] The curable composition may be a liquid having a relatively high viscosity at room temperature (25°C) that permits the curable composition to be applied to at least part of the surface of a substrate and then readily shaped to a desired configuration on the substrate surface, followed by exposure to ultraviolet (UV) light or other actinic radiation to cure the shaped curable composition to form a hard, durable, impact-resistant primer, ink or coating on the substrate. The curable composition may comprise, for example, a film or a coating composition, or a primer or an ink composition. For such applications, the curable composition may have a viscosity of from 100 to 5,000,000 cps at 25°C.

[0039] The curable composition alternatively may be a liquid having a relatively low viscosity at room temperature that permits the curable composition to be readily applied as a thin layer to at least part of the surface of a substrate (i.e., a substrate plate), followed by exposure to ultraviolet (UV) light or other actinic radiation to cure (e.g. photopolymerize) the thin layer of curable composition. In some embodiments, the curable composition comprises an inkjet formulation. In some embodiments, a curable composition comprising an inkjet formulation has a maximum viscosity of at most 15 cps, preferably at most 10 cps, more preferably at most 5 cps, at 45°C.

[0040] The amount of the liquid zinc (meth)acrylate complex included in the curable composition may be varied as may be desired depending upon the type of liquid zinc (meth)acrylate complex used, the attributes targeted in the cured substrate coating, and the types of polymerizing and / or non-polymerizing organic substances used, among possibly other factors.

[0041] According to various aspects of the invention, the curable composition may comprise at least 1%, at least 5%, or at least 10% by weight of the at least one liquid zinc (meth)acrylate complex, based on the total weight of the curable composition. In other aspects, the curable composition may comprise not more than 50%, not more than 45%, or not more than 40% by weight of the at least one liquid zinc (meth)acrylate complex, based on the total weight of the curable composition. The curable composition thus, for example, may be comprised of from 1 to 50%, 5 to 45%, or 10 to 40% by weight of the at least one liquid zinc (meth)acrylate complex based on the total weight of the curable composition.

[0042] The curable composition of the invention may comprise 5 to 95%, in particular 10 to 95%, more particularly 15 to 90%, even more particularly 20 to 85%, more particularly still 25 to 80% by weight of the at least one liquid zinc (meth)acrylate complex of the invention based on the total weight of the composition. In particular, the curable composition may comprise 5 to 50% or 10 to 50% or 15 to 50% or 20 to 50% or 25 to 50% or 30 to 50%, by weight of the at least one liquid zinc (meth)acrylate complex of the invention based on the total weight of the composition. Alternatively, the curable composition may comprise 50 to 95% or 55 to 95% or 60 to 95% or 65 to 95% or 70 to 95%, by weight of the at least one liquid zinc (meth)acrylate complex of the invention based on the total weight of the composition.

[0043] In accordance with certain embodiments, the curable composition may comprise 1 to 200, 5 to 100, or 15 to 70 parts by weight of the at least one liquid zinc (meth)acrylate complex per 100 parts by weight of the total weight of polymerizing organic substances (e.g., the total weight of polymerizing monomer(s) + polymerizing oligomer(s)).

[0044] In some embodiments, the at least one initiator may be present in the curable composition in a total amount of from 0.05% to 10%, preferably 0.05 to 5%, more preferably 0.1% to 2%, and most preferably 1% to 2% by weight, based on the total weight of the curable composition.

[0045] The curable compositions of the present invention comprise at least one liquid zinc (meth)acrylate complex comprising a ligand coordinated with zinc. The ligand may comprise at least one ethylenically unsaturated carboxylic acid. The complex may have at least one ligand based on an ethylenically unsaturated carboxylic acid. In other words, the ligand may be in the form of an ethylenically unsaturated carboxylic acid prior to its coordination with the zinc. Said ligand may be coordinated with the zinc by virtue of its carboxylic acid group, thus forming a zinc carboxylate complex. Such complexes, by virtue of including at least one carboxylate group containing a relatively large number of carbon atoms (e.g. at least 6 carbon atoms), have increased solubility in organic media, in particular improved solubility in the other components of the curable composition. Generally speaking, the solubility of the complex in organic media will tend to increase as the number of carbon atoms is increased, although to some extent the solubility will also depend upon the type of structural moiety or types of structural moieties in which the carbon atoms are present, as well as other types of atoms and functional groups which may be present.

[0046] In various embodiments of the invention, the ethylenically unsaturated carboxylic acid may, for example, contain six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen or more carbon atoms. In other embodiments, the ethylenically unsaturated carboxylic acid contains no more than 30, no more than 25 or no more than 20 carbon atoms. The carbon atoms may be aliphatic carbon atoms (including carbon atoms participating in carbon-carbon double bonds), as well as aromatic carbon atoms.

[0047] In certain embodiments, the ligand comprises at least one ethylenically unsaturated carboxylic acid. The at least one ethylenically unsaturated carboxylic acid comprises at least one carbon-carbon double bond that may be furnished by one or more acryloyl, methacryloyl, maleyl, allyl, propenyl, or vinyl, functional groups. Preferably, the at least one ethylenically unsaturated carboxylic acid comprises a (meth)acrylate-functionalized carboxylic acid.

[0048] The zinc (meth)acrylate complex has an acid value of at least 10 mg KOH / g complex, preferably at least 11 mg KOH / g complex, more preferably at least 12 mg KOH / g complex, more preferably at least 13 mg KOH / g complex, and most preferably at least 13.5 mg KOH / g complex. In other embodiments, the acid value of the zinc (meth)acrylate complex may be at least 25 mg KOH / g complex, preferably at least 50 mg KOH / g complex, more preferably at least 75 mg KOH / g complex, more preferably at least 90 mg KOH / g complex, and most preferably at least 125 mg KOH / g complex. As used herein, the ‘acid value’ of the zinc (meth)acrylate complex is a theoretical value determined by the amount of KOH needed to fully neutralize the residual Bronsted acid groups of the complex as determined by using an analytical technique, such as NMR, to determine the equivalent weight of those acid groups. Such Bronsted acids include carboxylic, phosphoric, phosphonic, and sulfonic acid. The particular acid value of the complex will depend on the desired delamination time based on certain conditions (temperature and pH) of the recycling solution and the specifics of the other constituents in the formulation, including the extent of their acid content, and the degree of cross-linking of the formulation.

[0049] Suitable ethylenically unsaturated carboxylic acids are carboxylic acids which contain at least one carbon-carbon double bond (i.e., at least one site of ethylenic unsaturation). Such double bonds render the complexes of the ethylenically unsaturated carboxylic acid capable of participating in the reactions that occur when the curable composition is cured, which may involve, for example, a free radical or cationic polymerization mechanism. While any such carbon-carbon bond may be present, in various embodiments of the invention the carbon-carbon double bond(s) is or are furnished by one or more functional groups selected from the group consisting of acryloyl (-O- C(=O)CH=CH2), methacryloyl (-O-C(=O)C(CH3)=CH2), maleyl (-O-C(=O)-CH=CH- C(=O)-O-), allyl (-CH2-CH=CH2), propenyl (-CH=CHCH3) and vinyl (-CH=CH2). Complexes of (meth)acrylate-functionalized carboxylic acids are utilized in one embodiment of the invention.

[0050] In some embodiments, the at least one ethylenically unsaturated carboxylic acid comprises a half ester reaction product of a hydroxy-functionalized ethylenically unsaturated compound and a polycarboxylic acid or carboxylic acid anhydride. In some embodiments, at least one carboxylic acid group of the half ester reaction product is esterified with one or more glycidyl-functional compounds, preferably a glycidyl ether or ester, more preferably an alkyl or aryl glycidyl ether or ester.

[0051] The zinc complex may additionally comprise a carboxylate portion that is not ethylenically unsaturated (i.e., does not contain any carbon-carbon double bonds) and / or an ethylenically unsaturated carboxylate portion containing fewer than six carbon atoms (e.g., an acrylate or methacrylate portion). Furthermore, the carboxylate portion may be comprised of a plurality of ethylenically unsaturated carboxylate moieties containing six or more carbon atoms which are the same as or different from each other.

[0052] It is also possible to employ ethylenically unsaturated carboxylic acids containing two or more carboxylic acid functional groups per molecule, thereby providing two or more -C(=O)O’ groups which are each ionically bonded with a single zinc cation.

[0053] In certain embodiments, the curable compositions of the present invention are characterized by the inclusion of one or more liquid zinc (meth)acrylate complexes corresponding to Formula (I):

[0054] Zn(OC(=O)CR1=CH2)x(O-C(=O)-R2-C(=O)-O-R3O-C(=O)CR4=CH2)y(I) wherein x and y are independently 0, 1, or 2, x + y = 2, R1and R4are the same or different and are H or CH3and R2and R3are the same or different and are divalent organic moieties each containing two or more carbon atoms.

[0055] In particular, R2may be a cyclohexyl moiety, which may be unsubstituted or substituted with one or more substituents such as an alkyl group (e.g., a Ci-Ce alkyl group, e.g., methyl). In one embodiment, R2is a 1,2-cyclohexyl moiety, which may have one or more substituents, such as alkyl groups, on the cyclohexane ring. In other embodiments, R2may be an alkylene moiety, which may be substituted or unsubstituted and which may correspond to the general formula -(CH2)m-, wherein m is an integer of 2 or more (e.g., 2- 20). In still other embodiments, R2may be a phenylene moiety, in particular an orthophenylene moiety, which may be unsubstituted or substituted with one or more substituents such as an alkyl group (e.g., a Ci-Ce alkyl group, e.g., methyl).

[0056] In particular, R3may be a branched or linear alkylene moiety, such as, but not limited to, -CH2CH2-, -CH(CH3)CH2- or an oligo-oxyalkylene moiety such as, but limited to, -(CH2CH2O)O-CH2CH2- wherein o is an integer of 1 or more (e.g., 1-10). In still other embodiments, R3may be a substituted alkylene moiety corresponding, for example, to the formula -CH(R5)CH2-, where R5may be an aryl group (e.g., phenyl or substituted phenyl), aralkyl group (e.g., benzyl), alkyl group (e.g., C1-C20 alkyl), or ether-containing hydrocarbyl group (e.g., Ar-O-CH2- or Alk-O-CIL-, where Ar is a substituted or unsubstituted aromatic group such as phenyl and Aik is an alkyl group).

[0057] Methods of Making Zinc (Meth) Aery late Complexes

[0058] Liquid zinc (meth)acrylate complexes of ethylenically unsaturated carboxylic acids useful in the present invention are known in the art and are described, for example, in U.S. Pat. Nos. 3,899,382; 6,399,672 and U.S. Pat. Pub. No. 2007 / 0054969. The disclosure of each of these patent documents is incorporated herein by reference in its entirety for all purposes. Such liquid zinc (meth)acrylate complexes are also available from commercial sources, in particular from Sartomer Americas of Arkema Inc. in Exton, Pennsylvania (“Sartomer”).

[0059] Suitable methods for making such complexes comprise reacting a hydroxyfunctionalized compound with a carboxylic polyacid or anhydride (i.e. cyclic anhydride) to form a carboxylic acid-functionalized compound and then reacting that carboxylic acid- functionalized compound with a compound which serves as a source of the cationic zinc portion of the salt. During the latter reaction, the carboxylic acid-functionalized compound is converted to the zinc salt form.

[0060] The hydroxy-functionalized compounds used in such preparations can be saturated or unsaturated compounds (i.e., such hydroxy-functionalized compounds may or may not contain one or more carbon-carbon double bonds). Saturated hydroxy-functionalized compounds can be used when the carboxylic polyacid and / or anhydride compound contains ethylenic unsaturation. Unsaturated hydroxy-functionalized compounds can be used when the carboxylic polyacid and / or anhydride compound does not contain ethylenic unsaturation. In other embodiments, both the hydroxy-functionalized compound and the carboxylic polyacid or anhydride compound contain one or more sites of ethylenic unsaturation (one or more carbon-carbon double bonds).

[0061] Ethylenically unsaturated functional groups suitable for use in the present invention include groups containing at least one carbon-carbon double bond, in particular a carboncarbon double bond capable of participating in a reaction (e.g., a free radical reaction) wherein at least one carbon of the carbon-carbon double bond becomes covalently bonded to an atom, in particular a carbon atom, in a second molecule. Such reactions may result in a polymerization or curing whereby the compound(s) containing one or more ethylenically unsaturated functional groups become(s) part of a polymerized matrix or polymeric chain.

[0062] The carbon-carbon double bond may, for example, be present as part of an a,P- unsaturated carbonyl moiety, e.g., an a,P-unsaturated ester moiety such as an acrylate functional group or a methacrylate functional group. A carbon-carbon double bond may also be present in the ethylenically unsaturated functional group in the form of a vinyl group or an allyl group. For the hydroxy-functionalized compounds containing an ethylenically unsaturated group, the unsaturation can be provided, for example, by (meth)acryloyl, maleyl, allyl, propenyl and / or vinyl groups. As used herein, the term “(meth)acryloyl” is intended to both include methacryloyl and acryloyl.

[0063] Some examples of such suitable hydroxy-functionalized compounds which contain one or more (meth)acrylate functional groups include hydroxyalkyl (meth)acrylates (e.g., hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate); alkyl glycidyl (meth)acrylates, aryl glycidyl (meth)acrylates and allyl glycidyl (meth)acrylates that have been ring-opened with hydroxyalkyl (meth)acrylates such as hydroxyethyl (meth)acrylate or hydroxypropyl (meth)acrylate; trimethylolpropane mono- and di-(meth)acrylates; pentaerythritol mono-, di- and tri-(meth)acrylates; dipentaerythritol mono-, di-, tri-, tetra- and penta-(meth)acrylates; glycerol mono- and di-(meth)acrylates; neopentyl glycol mono(meth)acrylate; alkylenediol mono(meth)acrylates such as hexanediol mono(meth)acrylate; tris(2-hydroxyethyl)isocyanurate mono- and di- (meth)acrylates; alkoxylated (e.g., ethoxylated or propoxylated) versions of all of the above; polyethylene glycol mono(meth)acrylates; polypropylene glycol mono(meth)acrylates; polyethylene / propylene glycol mono(meth)acrylates; polybutylene glycol mono(meth)acrylates; polytetramethylene glycol mono(meth)acrylates; hydroxy polycaprolactone mono(meth)acrylates and the like and combinations thereof. Residues of these compounds may be represented by R<3 >in Formulas (I) and (II).

[0064] Examples of hydroxy-functionalized compounds which contain one or more allyl groups include allyl alcohol, propoxylated and / or ethoxylated allyl alcohols, cinnamyl alcohol, crotyl alcohol, 3 -butene- l-ol, 3-butene-2-ol, linalool, 2-cyclohexen-l-ol, 2- cyclopenten-l-ol, 2-butene-l,4-diol, glycerol mono- and di-allyl ethers, trimethylolpropane mono- and di-allyl ethers and the like.

[0065] Other hydroxy-functionalized compounds containing one or more vinyl groups such as, for example, ethylene glycol vinyl ether, propylene glycol vinyl ether, 1,4- butanediol vinyl ether, 1,3-butanediol vinyl ether, 1,6-hexanediol vinyl ether, 2-methyl- 1,3 -propane diol vinyl ether, di(ethylene glycol) vinyl ether, di(propylene glycol) vinyl ether and the like can also be used.

[0066] Carboxylic polyacids or anhydrides which can be reacted with hydroxyfunctionalized compounds have either two or more carboxylic acid groups per molecule or at least one cyclic anhydride group per molecule or at least one anhydride group and at least one carboxylic group per molecule. The hydroxy-functionalized compound reacts with the carboxylic polyacid or anhydride to form a carboxylic acid-functionalized compound (which in some cases may be considered a “half-ester”) which is suitable for reaction with a compound capable of providing the cationic zinc portion of the salt (e.g., a metal compound, such as a metal oxide, for example zinc oxide). The carboxy equivalent functionality of suitable carboxylic polyacids and anhydrides may be about 2-30, preferably, 2-6.

[0067] Suitable compounds containing anhydride and / or carboxylic acid groups which react with the hydroxy -functionalized compounds include aromatic and aliphatic compounds such as phthalic anhydride, isophthalic acid, terephthalic acid, tetrabromophthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride (1,2-cy cl ohexanedi carboxylic anhydride) and alkyl-substituted analogues thereof, itaconic anhydride, itaconic acid, phthalic acid, trimellitic anhydride (which contains one cyclic anhydride and one carboxyl group), pyromellitic dianhydride, 5-norbomene-endo-2,3- dicarboxylic anhydride, naphthyl anhydride, naphthalene tetracarboxylic acid dianhydride, maleic anhydride, citraconic anhydride, diphenic anhydride, succinic anhydride, chlorendic anhydride, maleic acid, succinic acid, fumaric acid, oxalic acid, malonic acid, glutaric acid, glutaric anhydride, adipic acid, dimer fatty acids, hexahydrotrimellitic anhydride, biphenyl tetracarboxylic acid dianhydrides, diphthalic anhydrides, homophthalic anhydride, aconitic anhydride, benzophenone tetracarboxylic acid dianhydrides, styrene / maleic anhydride oligomers and polymers and (meth)acrylic acid oligomers, polymers and co-polymers.

[0068] One suitable method of making complexes of ethylenically unsaturated carboxylic acids suitable for use in the present invention involves reacting a zinc-containing compound with a carboxylic acid corresponding to Formula (II), which may be considered a “half-ester”:

[0069] HO-C(=O)-R2-C(=O)-O-R3-O-C(=O)CR4=CH2(II)

[0070] The zinc-containing compound serves as the source of zinc in the (meth)acrylate salt of Formula (I). That is, suitable zinc-containing compounds include those compounds capable of reacting with the carboxylic acid of Formula (II) and which can provide one or more zinc ions when reacted with a carboxylic acid of Formula (II). Suitable zinc- containing compounds may, in various embodiments of the invention, be selected from the group consisting of zinc-containing oxides, zinc-containing halides, zinc-containing alkoxides, zinc-containing hydroxides, zinc-containing nitrates, zinc-containing sulfates, zinc-containing carboxylates, zinc-containing carbonates and combinations thereof. For example, the zinc-containing compound may correspond to the formula Zn(X)n, wherein each X is independently oxygen, halide, alkoxide, hydroxide, nitrate, sulfate, carboxylate, carbonate or combinations thereof if more than one X is present, and n=the valency of zinc. Zinc-containing oxides in particular may be used, especially zinc oxide or calcium oxide.

[0071] Suitable compounds capable of providing the cationic zinc portion of the salt when reacted with the hydroxy-functionalized compound / carboxylic polyacid and / or anhydride reaction products (e.g., half esters) prepared as described above include both metallic zinc and non-metallic zinc compounds. Suitable compounds for this purpose include compounds containing zinc, for example, oxides, halides, alkoxides, hydroxides, nitrates, sulfates, carboxylates and carbonates of zinc. The most preferred compound for reaction with the hydroxy-functionalized compound / polycarboxylic acid and / or anhydride reaction products is zinc oxide, since it reacts very easily and is readily available.

[0072] As previously mentioned, the complex may comprise a half ester reaction product of a hydroxy-functionalized ethylenically unsaturated compound and a poly carboxylic acid or carboxylic acid anhydride. In some embodiments, at least one carboxylic acid group of the half ester reaction product is esterified with one or more glycidyl-functional compounds, preferably a glycidyl ether or ester, more preferably an alkyl or aryl glycidyl ether or ester.

[0073] Glycidyl ethers can be prepared from a hydroxyl-functional precursor and an epoxy compound such as epichlorohydrin. Many of the hydroxyl-functional components listed in the section above are suitable for preparation of aliphatic glycidyl ethers. Specific examples of precursors for aliphatic glycidyl ethers include: 1,2-ethanediol, 1,2- propanediol, 1,3 -propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10- decanediol, 1,12-dodecanediol, 1,3 -butanediol, 2,2-dimethyl-l,3-propanediol, 2-methyl- 1,3 -propanediol, 1,4- and 1,6-dimethylolcylcohexane, diethylene glycol, tri ethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol), polypropylene glycol), poly(tetramethylene glycol), glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, di-glycerol, di-trimethyolpropane, di-pentaerytritol, sorbitol and ethoxylated and / or propoxylated derivatives of the above. Specific examples of precursors for aromatic glycidyl ethers include: bisphenol A, bisphenol F and resorcinol.

[0074] The curable compositions utilized in the methods of the present invention are comprised of polymerizing monomers and / or oligomers. The polymerizing monomers and / or oligomers are distinct from the liquid zinc (meth)acrylate complex as defined above. As used herein, the term “polymerizing” means capable of participating in a polymerization or curing reaction to form a polymeric structure. The polymerizing monomers and / or oligomers may be monomeric and / or oligomeric in structure and may be characterized as containing one, two, three or more polymerizing functional groups per molecule. Suitable polymerizing functional groups include in particular functional groups capable of participating in chain-growth and ring-opening polymerization mechanisms, such as ethylenically and ethynically unsaturated functional groups (e.g., (meth)acryloyl, vinyl, olefinic and alkyne functional groups) and heterocyclic-functional groups (e.g., epoxide and oxetane functional groups).

[0075] Polymerizing functional groups which polymerize via free radical and / or cationic mechanisms are particularly preferred. A polymerizing organic substance may include more than one type of polymerizing functional group. The molecular weight of suitable polymerizing monomers and / or oligomers is not particularly limited and may, for example, be from 120 to 50,000 g / mol or from 150 to 25,000 g / mol (in the case where the polymerizing organic substance is an oligomer, “molecular weight” refers to number average molecular weight as determined by gel permeation chromatography using polystyrene calibration standards). Combinations of different polymerizing monomers and / or oligomers may be used in the curable compositions of the present invention. In particular, the curable compositions may comprise at least one polymerizing monomer and / or at least one polymerizing oligomer.

[0076] According to certain embodiments, the total weight of polymerizing oligomer in the curable composition is at least as much as the total weight of polymerizing monomer. For example, the weight ratio of polymerizing oligomer : polymerizing monomer may be from 50 : 50 to 90 : 10.

[0077] According to other embodiments, the total weight of polymerizing monomer in the curable composition is at least as much as the total weight of polymerizing oligomer. For example, the weight ratio of polymerizing monomer : polymerizing oligomer may be from 50 : 50 to 90 : 10.

[0078] Preferably, the polymerizing monomers and / or oligomers are selected such that in combination as present in the curable composition the combination is a liquid at least in the temperature range between 0°C and 60°C. The polymerizing monomer may advantageously function as a reactive diluent and reduce the viscosity of the composition.

[0079] Suitable illustrative types of polymerizing monomers and / or oligomers that may be mentioned include, but are not limited to, epoxides (oxiranes), oxetanes, oxolanes, cyclic acetals, and other cyclic ethers, cyclic lactones, vinyl compounds (both aliphatic and aromatic), cyanoacrylates, (meth)acrylamides, and (meth)acrylates (which are particularly preferred). As used herein, the term “(meth)acrylate” refers to both acrylate (-O-C(=O)- CH=CH2) and methacrylate (-O-C(=O)-C(CH3)=CH2) functional groups.

[0080] A polymerizing monomer and / or oligomer contains at least one moiety capable of participating in a polymerization or curing reaction whereby a plurality of polymerizing monomer and / or oligomer molecules become covalently bonded to each other to form a polymeric structure. Suitable reactive moieties include sites of ethylenic unsaturation (i.e., carbon-carbon double bonds, C=C). Such sites of ethylenic unsaturation can be provided, for example, by (meth)acryloyl, maleyl, allyl, propenyl, and / or vinyl groups. As used herein, the term "(meth)acryloyl" is intended to both include methacryloyl and acryloyl, as found in (meth)acrylates and (meth)acrylamides.

[0081] As previously mentioned, ethylenically unsaturated functional groups suitable for use in the polymerizing monomers and / or oligomers of the curable composition include groups containing at least one carbon-carbon double bond, in particular a carbon-carbon double bond capable of participating in a reaction (e.g., a free radical reaction) wherein at least one carbon of the carbon-carbon double bond becomes covalently bonded to an atom, in particular a carbon atom, in a second molecule. Such reactions may result in a polymerization or curing whereby the monomer and / or oligomer(s) containing one or more ethylenically unsaturated functional groups become(s) part of a polymerized matrix or polymeric chain. The carbon-carbon double bond may, for example, be present as part of an a,P~unsaturated carbonyl moiety, e.g., an a,P~unsaturated ester moiety such as an acrylate functional group (H2C=CH-C(=O)O-) or a methacrylate functional group (H2C=C(CH3)-C(=O)O-). A carbon-carbon double bond may also be present in the ethylenically unsaturated functional group in the form of a vinyl group -CH=CH2 or an allyl group, -CH2-CH=CH2.

[0082] A polymerizable monomer may comprise at least one polymerizing functional group selected from the group consisting of acrylate (including cyanoacrylate), methacrylate, acrylamide, methacrylamide, styrene, maleate, fumarate, itaconate, allyl, propenyl, vinyl and combinations thereof. In particular, a polymerizable monomer may comprise at least one polymerizing functional group selected from the group consisting of acrylate, methacrylate, allyl, vinyl, and combinations thereof.

[0083] In certain embodiments, the curable compositions employed in the present invention are characterized by comprising at least one (meth)acrylate-functionalized monomer and / or oligomer. A (meth)acrylate-functionalized monomer and / or oligomer may be described as a monomer and / or oligomer bearing one or more (meth)acrylate functional groups per molecule. As used herein, the term “(meth)acrylate” refers to both acrylate and methacrylate functional groups. (Meth)acrylate-functionalized monomers and / or oligomers suitable for use in the present invention may be generally described as ethylenically unsaturated monomers and / or oligomers containing at least one carboncarbon double bond alpha to an ester group (a compound containing at least one a,P~ unsaturated ester moiety), in particular a carbon-carbon double bond capable of participating in a free radical reaction, in particular a reaction initiated by ultraviolet radiation or electron beam radiation. Such reactions may result in a polymerization or curing whereby the (meth)acrylate-functionalized monomer and / or oligomer becomes part of a polymerized matrix or polymeric chain. In various embodiments of the invention, the (meth)acrylate-functionalized monomer and / or oligomer may contain one, two, three, four, five or more (meth)acrylate functional groups per molecule. Combinations of multiple (meth)acrylate-functionalized monomer and / or oligomers containing different numbers of (meth)acrylate groups may be utilized in the curable compositions of the present invention.

[0084] The curable compositions used in the present invention thus may contain one or more (meth)acrylate functionalized monomers and / or oligomers capable of undergoing free radical polymerization (curing) initiated by exposure to actinic radiation (e.g., ultraviolet light) or electron beam radiation. The (meth)acrylate-functionalized monomer and / or oligomers may be oligomers or monomers or, preferably, a combination of oligomer(s) and monomer(s).

[0085] Any of the following types of (meth)acrylate-functionalized monomer and / or oligomers may, for example, be employed in the curable compositions of the present invention, possibly or optionally in combination with one or more other types of polymerizing monomers and / or oligomers as co-reactants: monomers such as (meth)acrylate esters of aliphatic mono-alcohols, (meth)acrylate esters of alkoxylated aliphatic mono-alcohols, (meth)acrylate esters of aliphatic polyols, (meth)acrylate esters of alkoxylated aliphatic polyols, (meth)acrylate esters of aromatic ring-containing alcohols, and (meth)acrylate esters of alkoxylated aromatic ring-containing alcohols; and oligomers such as epoxy (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates (including amine- and sulfide-modified derivatives thereof); and combinations thereof. Most preferably, at least one monomer is selected from the group consisting of hydroxy ethyl methacrylate, hydroxypropyl methacrylate, isobornyl methacrylate, polyethylene glycol dimethacrylates and trimethylolpropane trimethacrylate.

[0086] According to one aspect of the invention, the curable composition contains at least one hydroxyalkyl (meth)acrylate, such as hydroxyethyl methacrylate and / or hydroxypropyl methacrylate. For example, the curable composition may contain from 5 to 30 weight % in total of hydroxyalkyl (meth)acrylate, based on the total weight of polymerizing monomers and / or oligomers in the curable composition. However, in other embodiments, the curable composition may contain little or no hydroxyalkyl (meth)acrylate (e.g., less than 5 weight % or 0 weight %, based on the total weight of polymerizing monomers and / or oligomers), since at least some hydroxyalkyl (meth)acrylates have sensitizing properties.

[0087] According to another aspect of the invention, the curable composition contains at least one cycloalkyl (meth)acrylate, in particular isobomyl (meth)acrylate. For example, the curable composition may contain from 1 to 25 or 5 to 15 weight % of cycloalkyl (meth)acrylate (e.g., isobomyl methacrylate), based on the total weight of polymerizing monomers and / or oligomers in the curable composition. Cyclohexyl (meth)acrylates, tetrahydrofurfuryl (meth)acrylates, and cyclic trimethylolpropane formal (meth)acrylates represent other types of cycloalkyl (meth)acrylate useful in the present invention.

[0088] According to another aspect of the invention, the curable composition contains at least one ethylene glycol- or poly(ethylene glycol)-based (meth)acrylate, such as a poly(ethyleneglycol) di(meth)acrylate. Such substances may be described as (meth)acrylates of ethylene glycol and poly(ethylene glycol), wherein the polyethylene glycol may contain two or more oxy ethylene units derived from ethylene oxide per molecule. In certain embodiments, the substance comprises an ethylene glycol segment or polyethylene glycol segment having a number average molecular weight of from about 100 g / mol to about 1000 g / mol. Such a segment may correspond to the structural formula - (CH2CH2O)n-, wherein n is from 2 to 25 on average. For example, the curable composition may contain from 1 to 80 or 5 to 60 weight % of poly(ethylene glycol) di(meth)acrylate, based on the total weight of polymerizing monomers and / or oligomers in the curable composition. Ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, PEG-9 di(meth)acrylate (containing an average of about 9 oxy ethylene units per molecule), PEG200 di(meth)acrylate (containing a polyethylene glycol segment having a number average molecular weight of about 200 g / mol) and PEG600 di(meth)acrylate (containing a polyethylene glycol segment having a number average molecular weight of about 600 g / mol) represent other types of ethylene glycol- or poly(ethylene glycol)-based (meth)acrylates useful in the present invention. The use of such ethylene glycol- or poly(ethylene glycol)-based (meth)acrylates in the curable compositions is advantageous in that such substances generally are low- to non-sensitizing, unlike certain other types of (meth)acrylate-functionalized monomers.

[0089] In yet another aspect of the invention, the curable composition contains at least one (meth)acrylate-functionalized monomer containing three or more (meth)acrylate functional groups per molecule, in particular (meth)acrylates of polyols containing three or more hydroxyl groups per molecule and alkoxylated derivatives thereof such as glycerol, trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, triethylolpropane and ethoxylated and / or propoxylated derivatives thereof in which the polyol is reacted with 1 to 10 moles of ethylene oxide and / or propylene oxide per mole of polyol. For example, the curable composition may contain from 0.1 to 20 or 0.5 to 10 weight % in total of such (meth)acrylate-functionalized monomers containing three or more (meth)acrylate functional groups per molecule (e.g., trimethylolpropane trimethacrylate).

[0090] Suitable (meth)acrylate-functionalized oligomers include, for example, polyester (meth)acrylates, epoxy (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates (sometimes also referred to as polyurethane (meth)acrylates or urethane (meth)acrylate oligomers) and combinations thereof, as well as amine-modified and sulfide-modified variations thereof. Certain of these (meth)acrylate-functionalized oligomers may function as flexibilizers in the cured articles obtained by curing of the curable composition, i.e., their inclusion helps to increase the flexibility of the cured articles prepared therefrom.

[0091] According to some embodiments, the polymerizing oligomer is a (meth)acrylate- functionalized oligomer, preferably selected from acidic acrylic (meth)acrylates, epoxy (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates (including amine- and sulfide-modified derivatives thereof), and combinations thereof, more preferably urethane (meth)acrylates, most preferably urethanes based on aliphatic and / or aromatic polyester polyols, polyether polyols and polycarbonate polyols and aliphatic and / or aromatic polyester diisocyanates and polyether diisocyanates capped with (meth)acrylate end-groups.

[0092] Exemplary polyester (meth)acrylates include the reaction products of acrylic or methacrylic acid or mixtures thereof with hydroxyl group-terminated polyester polyols. The reaction process may be conducted such that a significant concentration of residual hydroxyl groups remains in the polyester (meth)acrylate or may be conducted such that all or essentially all of the hydroxyl groups of the polyester polyol have been (meth)acrylated. The polyester polyols can be made by polycondensation reactions of polyhydroxyl- functional components (in particular, diols) and polycarboxylic acid functional compounds (in particular, dicarboxylic acids and anhydrides). To prepare the polyester (meth)acrylates, the hydroxyl groups of the polyester polyols are then partially or fully esterified by reacting with (meth)acrylic acid, (meth)acryloyl chloride, (meth)acrylic anhydride or the like. Polyester (meth)acrylates may also be synthesized by reacting a hydroxyl-containing (meth)acrylate such as a hydroxyalkyl (meth)acrylate (e.g., hydroxyethyl acrylate) with a polycarboxylic acid. The polyhydroxyl-functional and polycarboxylic acid functional components can each have linear, branched, cycloaliphatic or aromatic structures and can be used individually or as mixtures.

[0093] Examples of suitable epoxy (meth)acrylates include the reaction products of acrylic or methacrylic acid or mixtures thereof with glycidyl ethers or esters.

[0094] Exemplary polyether (meth)acrylate oligomers include, but are not limited to, the condensation reaction products of acrylic or methacrylic acid or mixtures thereof with polyetherols which are polyether polyols. Suitable polyetherols can be linear or branched substances containing ether bonds and terminal hydroxyl groups. Polyetherols can be prepared by ring opening polymerization of epoxides and other oxygen-containing heterocyclic compounds (e.g., ethylene oxide, 1,2-propylene oxide, butene oxide, tetrahydrofuran and combinations thereof) with a starter molecule. Suitable starter molecules include water, hydroxyl-functional materials, polyester polyols and amines. Polyetherols may also be obtained by the condensation of diols such as glycols.

[0095] Urethane (meth)acrylates (sometimes also referred to as “polyurethane (meth)acrylates” or “urethane (meth)acrylate oligomers”) capable of being used in the curable compositions of the present invention include urethanes based on aliphatic and / or aromatic polyester polyols, polyether polyols and polycarbonate polyols and aliphatic and / or aromatic polyester diisocyanates and polyether diisocyanates capped with (meth)acrylate end-groups.

[0096] In various embodiments, the urethane (meth)acrylates may be prepared by reacting aliphatic and / or aromatic polyisocyanates (e.g., diisocyanates, triisocyanates) with OH group terminated polyester polyols (including aromatic, aliphatic and mixed aliphatic / aromatic polyester polyols), polyether polyols, polycarbonate polyols, polycaprolactone polyols, polydimethysiloxane polyols, or polybutadiene polyols, or combinations thereof to form isocyanate-functionalized oligomers which are then reacted with hydroxyl-functionalized (meth)acrylates such as hydroxyethyl (meth)acrylate or hydroxypropyl (meth)acrylate to provide terminal (meth)acrylate groups. For example, the urethane (meth)acrylates may contain two, three, four or more (meth)acrylate functional groups per molecule. Other orders of addition may also be practiced to prepare the polyurethane (meth)acrylate, as is known in the art. For example, the hydroxylfunctionalized (meth)acrylate may be first reacted with a polyisocyanate to obtain an isocyanate-functionalized (meth)acrylate, which may then be reacted with an OH group terminated polyester polyol, polyether polyol, polycarbonate polyol, polycaprolactone polyol, polydimethysiloxane polyol, polybutadiene polyol, or a combination thereof. In yet another embodiment, a polyisocyanate may be first reacted with a polyol, including any of the aforementioned types of polyols, to obtain an isocyanate-functionalized polyol, which is thereafter reacted with a hydroxyl-functionalized (meth)acrylate to yield a polyurethane (meth)acrylate. Alternatively, all the components may be combined and reacted at the same time.

[0097] Any of the above-mentioned types of oligomers may be modified with amines or sulfides (e.g., thiols), following procedures known in the art. Such amine- and sulfide- modified oligomers may be prepared, for example, by reacting a relatively small portion (e.g., 2-15%) of the (meth)acrylate functional groups present in the base oligomer with an amine (e.g., a secondary amine) or a sulfide (e.g., a thiol), wherein the modifying compound adds to the carbon-carbon double bond of the (meth)acrylate in a Michael addition reaction.

[0098] Illustrative examples of suitable monomeric (meth)acrylate-functionalized monomer and / or oligomers include (meth)acrylated mono- and polyols (polyalcohols) and (meth)acrylated alkoxylated mono-alcohols and polyols. The mono-alcohols and polyols may be aliphatic (including one or more cycloaliphatic rings) or may contain one or more aromatic rings (as in the case of phenol or bisphenol A). “Alkoxylated” means that the base mono-alcohol or polyol has been reacted with one or more epoxides such as ethylene oxide and / or propylene oxide so as to introduce one or more ether moieties (e.g., - CH2CH2-O-) onto one or more hydroxyl groups of the mono-alcohol or polyol, prior to esterification to introduce one or more (meth)acrylate functional groups. For example, the amount of epoxide reacted with the mono-alcohol or polyol may be from about 1 to about 30 moles of epoxide per mole of mono-alcohol or polyol. Examples of suitable monoalcohols include, but are not limited to, straight chain, branched and cyclic C1-C54 monoalcohols (which may be primary, secondary or tertiary alcohols). For instance, the monoalcohol may be a C1-C7 aliphatic mono-alcohol. In another embodiment, the mono-alcohol may be a C8-C24 aliphatic mono-alcohol (e.g., lauryl alcohol, stearyl alcohol). Examples of suitable polyols include organic compounds containing two, three, four or more hydroxyl groups per molecule such as glycols (diols), e.g., ethylene glycol, 1,2- or 1,3-propylene glycol, or 1,2-, 1,3- or 1,4-butylene glycol, neopentyl glycol, trimethylolpropane, triethylolpropane, pentaerythritol, glycerol and the like.

[0099] Representative, but not limiting, examples of suitable monomeric (meth)acrylate- functionalized compounds include: 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, longer chain aliphatic di(meth)acrylates (such as those generally corresponding to the formula H2C=CRC(=O)-O-(CH2)m-O- C(=O)CR’=CH2, wherein R and R’ are independently H or methyl and m is an integer of 8 to 24), alkoxylated (e.g., ethoxylated, propoxylated) hexanediol di(meth)acrylates, alkoxylated (e.g., ethoxylated, propoxylated) neopentyl glycol di(meth)acrylates, dodecyl di(meth) acrylates, cyclohexane dimethanol di(meth)acrylates, diethylene glycol di(meth)acrylates, dipropylene glycol di(meth)acrylates, alkoxylated (e.g., ethoxylated, propoxylated) bisphenol A di(meth)acrylates, ethylene glycol di(meth)acrylates, neopentyl glycol di(meth)acrylates, tricyclodecane dimethanol diacrylates, triethylene glycol di(meth)acrylates, tetraethylene glycol di(meth)acrylates, tripropylene glycol di(meth)acrylates, ditrimethylolpropane tetra(meth)acrylates, dipentaerythritol penta(meth)acrylates, alkoxylated (e.g., ethoxylated, propoxylated) pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylates, pentaerythritol tetra(meth)acrylate, alkoxylated (e.g., ethoxylated, propoxylated) trimethylolpropane tri(meth)acrylates, alkoxylated (e.g., ethoxylated, propoxylated) glyceryl tri(meth)acrylates, trimethylolpropane tri(meth)acrylates, pentaerythritol tri(meth)acrylates, tris (2-hydroxy ethyl) isocyanurate tri(meth)acrylates, 2(2- ethoxyethoxy) ethyl (meth)acrylates, 2-phenoxy ethyl (meth)acrylates, 3,3,5- trimethylcyclohexyl (meth)acrylates, alkoxylated lauryl (meth)acrylates, alkoxylated phenol (meth)acrylates, alkoxylated tetrahydrofurfuryl (meth)acrylates, caprolactone (meth)acrylates, cyclic trimethylolpropane formal (meth)acrylates, dicyclopentadienyl (meth)acrylates, diethylene glycol methyl ether (meth)acrylates, alkoxylated (e.g., ethoxylated, propoxylated) nonyl phenol (meth)acrylates, isobornyl (meth)acrylates, isodecyl (meth)acrylates, isooctyl (meth)acrylates, lauryl (meth)acrylates, methoxy polyethylene glycol (meth)acrylates, octyldecyl (meth)acrylates (also known as stearyl (meth)acrylates), tetrahydrofurfuryl (meth) acrylates, tridecyl (meth)acrylates, triethylene glycol ethyl ether (meth)acrylates, t-butyl cyclohexyl (meth)acrylates, dicyclopentadiene di(meth)acrylates, phenoxyethanol (meth)acrylates, octyl (meth)acrylates, decyl (meth)acrylates, dodecyl (meth)acrylates, tetradecyl (meth)acrylates, cetyl (meth)acrylates, hexadecyl (meth)acrylates, behenyl (meth)acrylates, diethylene glycol ethyl ether (meth)acrylates, diethylene glycol butyl ether (meth)acrylates, triethylene glycol methyl ether (meth)acrylates, dodecanediol di (meth)acrylates, dipentaerythritol penta / hexa(meth)acrylates, pentaerythritol tetra(meth)acrylates, alkoxylated (e.g., ethoxylated, propoxylated) pentaerythritol tetra(meth)acrylates, di-trimethylolpropane tetra(meth)acrylates, alkoxylated (e.g., ethoxylated, propoxylated) glyceryl tri(meth)acrylates, and tris (2-hydroxyethyl) isocyanurate tri(meth)acrylates, and combinations thereof.

[0100] Other types of polymerizing monomers and / or oligomers containing ethylenically unsaturated functional groups suitable for use in the curable compositions of the present invention include cyanoacrylates, vinyl esters, 1,1 -diester- 1 -alkenes, 1,1 -diketo- 1 -alkenes, 1 -ester- 1 -keto- 1 -alkenes and itaconates, including methylene malonates and / or methylene beta-diketones.

[0101] The amount of (meth)acrylate-functionalized oligomer may be varied based on the viscosity of the oligomer or the tensile properties desired in the curable composition when cured. For example, the curable composition may contain from 1 to 80 or 5 to 60 weight % of (meth)acrylate-functionalized oligomer, based on the total weight of polymerizing monomers and / or oligomers in the curable composition. A suitable (meth)acrylate- functionalized oligomer could be diHEMA trimethylhexyl dicarbamate (UDMA).

[0102] According to particularly preferred embodiments of the invention, the polymerizing monomer(s) and / or oligomer(s) which make up components a) and b) of the curable composition is or are selected to be compatible with the liquid zinc (meth)acrylate complex also present in the curable composition. As used herein, the term “compatible” means that a curable composition does not gel or increase in viscosity to an unacceptable degree when the components of the curable composition are combined (that is, the curable composition remains workable, i.e., capable of being applied and shaped in accordance with its intended end use application).

[0103] Multifunctional (Meth)acrylate Oligomers

[0104] The curable compositions useful in the methods of the present may in certain preferred embodiments contain as a polymerizable oligomer one or more multifunctional (meth)acrylate oligomers. Such oligomers are typically of moderate molecular weight and contain two or more (meth)acrylate functional groups per molecule (i.e., in this content the term “multifunctional”) refers to the presence of a plurality of (meth)acrylate functional groups in the oligomer molecule). This type of oligomer may also be referred to as multi(meth)acrylate-functionalized oligomers due to the presence of multiple (meth)acrylate functional groups. Such (meth)acrylate functional groups (e.g., methacrylate functional groups corresponding to the structure -O-C(=O)C(CH3)=CH2) and acrylate functional groups corresponding to the structure -O-C(=O)CH=CH2) are capable of reacting with other ethylenically unsaturated groups present in the curable composition when the curable composition is cured, for example through a free radical or cationic polymerization.

[0105] Mixtures of different multifunctional (meth)acrylate oligomers may be used. The number average molecular weight of the multifunctional (meth)acrylate oligomer(s) may be, in various embodiments of the invention, at least 500 daltons, at least 750 daltons, at least 1000 daltons, at least 1500 daltons or at least 2000 daltons and not more than 10,000 daltons, not more than 9000 daltons or not more than 8000 daltons. In one embodiment, the curable composition comprises a di(meth)acrylate-functionalized oligomer or mixture of di(meth)acrylate-functionalized oligomers. In other embodiments, the curable composition does not contain any multifunctional (meth)acrylate oligomer other than di(meth)acrylate- functionalized oligomer. In certain embodiments, the curable composition may additionally comprise one or more mono(meth)acrylate-functionalized oligomers (i.e., oligomers containing a single (meth)acrylate functional group per molecule).

[0106] Suitable free radical-curable multifunctional (meth)acrylate oligomers include, for example, polyester (meth)acrylates, epoxy (meth)acrylates, polyether (meth)acrylates, polyurethane (meth)acrylates, acrylic (meth)acrylate oligomers, epoxy-functional (meth)acrylate oligomers and combinations thereof, each of which contains at least two (meth)acrylate functional groups per molecule (which may be positioned at a terminus of the molecule and / or along the backbone of the molecule).

[0107] Each type of multifunctional (meth)acrylate oligomer may provide specific properties to the composition when cured and thus can be selected and varied as may be needed to achieve certain desired physical properties in the cured composition. Such oligomers generally impart toughness to the photo-cured composition as compared to (meth)acrylate-functionalized monomers and also can be employed to tailor hardness, flexibility, adhesion and / or chemical resistance. In the present invention, multifunctional (meth)acrylate oligomers, especially those of higher molecular weight (e.g., oligomers having number average molecular weights of from 2000 g / mol to 10,000 g / mol or even higher) have been found to be useful for providing the composition, when cured, with flexibility (high elongation at break) and impact resistance.

[0108] Exemplary polyester (meth)acrylates include the reaction products of acrylic or methacrylic acid or mixtures thereof with hydroxyl group-terminated polyester polyols. The reaction process may be conducted such that a significant concentration of residual hydroxyl groups remain in the polyester (meth)acrylate or may be conducted such that all or essentially all of the hydroxyl groups of the polyester polyol have been (meth)acrylated. The polyester polyols can be made by polycondensation reactions of polyhydroxyl functional components (in particular, diols) and polycarboxylic acid functional compounds (in particular, dicarboxylic acids and anhydrides). The polyhydroxyl functional and polycarboxylic acid functional components can each have linear, branched, cycloaliphatic or aromatic structures and can be used individually or as mixtures.

[0109] Examples of suitable epoxy (meth)acrylates include the reaction products of acrylic or methacrylic acid or mixtures thereof with glycidyl ethers (such as bisphenol diglycidyl ethers and oligomeric epoxy resins) or esters. Epoxy (meth)acrylate oligomers are available from commercial sources such as Sartomer, including Sartomer's CN159 product.

[0110] Suitable polyether (meth)acrylates include, but are not limited to, the condensation reaction products of acrylic or methacrylic acid or mixtures thereof with polyetherols which are polyether polyols. Suitable polyetherols can be linear or branched substances containing ether bonds and terminal hydroxyl groups. Polyetherols can be prepared by ring opening polymerization of cyclic ethers such as tetrahydrofuran or alkylene oxides with a starter molecule. Suitable starter molecules include water, hydroxyl functional materials (e.g., polyols, bisphenols and the like), polyester polyols and amines.

[0111] Polyurethane (meth)acrylates (sometimes also referred to as “urethane (meth)acrylates” or “(meth)acrylate-functionalizeed urethane oligomers”) capable of being used in the curable compositions of the present invention include urethanes based on aliphatic and / or aromatic polyester polyols and polyether polyols and aliphatic and / or aromatic polyester diisocyanates and polyether diisocyanates capped with (meth)acrylate end-groups. Suitable polyurethane (meth)acrylates include, for example, aliphatic polyester-based urethane diacrylate oligomers, aliphatic poly ether-based urethane diacrylate oligomers, as well as aliphatic polyester / polyether-based urethane diacrylate oligomers.

[0112] In various embodiments, the polyurethane (meth)acrylates may be prepared by reacting aliphatic and / or aromatic diisocyanates with OH group terminated polyester polyols (including aromatic, aliphatic and mixed aliphatic / aromatic polyester polyols), polyether polyols, polycarbonate polyols, polycaprolactone polyols, polydimethysiloxane polyols or polybutadiene polyols or combinations thereof to form isocyanate- functionalized oligomers which are then reacted with hydroxy-functionalized (meth)acrylates such as hydroxyethyl acrylate or hydroxyethyl methacrylate to provide terminal (meth)acrylate groups. For example, the polyurethane (meth)acrylates may contain two, three, four or more (meth)acrylate functional groups per molecule.

[0113] One or more urethane diacrylates are employed in certain embodiments of the invention. For example, the curable composition may comprise (in addition to the inventive mono functional compound) at least one urethane diacrylate comprising a difunctional aromatic urethane acrylate oligomer, a difunctional aliphatic urethane acrylate oligomer and combinations thereof. In certain embodiments, a difunctional aromatic urethane acrylate oligomer, such as that available from Sartomer under the trade name CN9782, may be used as the at least one urethane diacrylate. In other embodiments, a difunctional aliphatic urethane acrylate oligomer, such as that available from Sartomer under the trade name CN9023, may be used as the at least one urethane diacrylate. CN9782, CN9023, CN978, CN965, CN966, CN9031, CN8881 and CN8886, all available from Sartomer, may all be advantageously employed as urethane diacrylates in the curable compositions of the present invention.

[0114] Suitable acrylic (meth)acrylate oligomers (sometimes also referred to in the art as “acrylic oligomers”) include oligomers which may be described as substances having an oligomeric acrylic backbone which is functionalized with two or more (meth)acrylate groups (which may be at a terminus of the oligomer or pendant to the acrylic backbone). The acrylic backbone may be a homopolymer, random copolymer or block copolymer comprised of repeating units of acrylic monomers. The acrylic monomers may be any monomeric (meth)acrylate such as Ci-Ce alkyl (meth)acrylates as well as functionalized (meth)acrylates such as (meth)acrylates bearing hydroxyl, carboxylic acid and / or epoxy groups. Acrylic (meth)acrylate oligomers may be prepared using any procedures known in the art such as oligomerizing 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 a functionalized oligomer intermediate, which is then reacted with one or more (meth)acrylate-containing reactants to introduce the desired (meth)acrylate functional groups. Suitable acrylic (meth)acrylate oligomers are commercially available from Sartomer under products designated as CN820, CN821, CN822 and CN823, for example.

[0115] Optionally (meth)acrylate-functionalized acidic acrylic oligomers

[0116] According to some embodiments, the curable compositions useful in the methods of the invention may contain as polymerizable oligomers one or more optionally (meth)acrylate-functionalized acidic acrylic oligomers. Such oligomers may be conveniently prepared by copolymerizing acrylic acid with one or more ethylenically unsaturated co-monomers to form an acidic acrylic copolymer. The ethylenically unsaturated polymerizable co-monomer may be selected in order to enhance the flexibility, strength and / or modulus, among other attributes, of a cured polymer prepared using curable composition.

[0117] According to some preferred embodiments, the ethylenically unsaturated comonomer may comprise at least one (meth)acrylate monomer. In particular, the ethylenically unsaturated co-monomer comprises a (meth)acrylate monomer. According to some embodiments, the ethylenically unsaturated co-monomer may comprise a mixture of (meth)acrylate monomers.

[0118] As used herein, the term “(meth)acrylate monomer” means a monomer comprising a (meth)acrylate group, in particular an acrylate group. The term “(meth)acrylate group” encompasses acrylate groups (-O-CO-CH=CH2) and methacrylate groups (-O-CO- C(CH3)=CH2).

[0119] The (meth)acrylate monomer may have a molecular weight of less than 600 g / mol, in particular from 100 to 550 g / mol, more particularly 200 to 500 g / mol.

[0120] The (meth)acrylate monomer may have 1 to 6 (meth)acrylate groups, in particular 1 to 3 (meth)acrylate groups.

[0121] The (meth)acrylate monomer may comprise a mixture of (meth)acrylate monomers having different functionalities. For example, the (meth)acrylate monomer may comprise a mixture of a (meth)acrylate monomer containing a single acrylate or methacrylate group per molecule (referred to herein as “mono(meth)acrylate compounds”) and a (meth)acrylate monomer containing 2 or more, preferably 2 or 3, acrylate and / or methacrylate groups per molecule.

[0122] In one embodiment, the (meth)acrylate monomer comprises a mono(meth)acrylate monomer.

[0123] Examples of suitable mono(meth)acrylate monomers include, but are not limited to, mono-(meth)acrylate esters of aliphatic alcohols (wherein the aliphatic alcohol may be straight chain, branched or alicyclic and may be a mono-alcohol, a di-alcohol or a polyalcohol, provided only one hydroxyl group is esterified with (meth)acrylic acid); mono-(meth)acrylate esters of aromatic alcohols (such as phenols, including alkylated phenols); mono-(meth)acrylate esters of alkylaryl alcohols (such as benzyl alcohol); mono- (meth)acrylate esters of oligomeric and polymeric glycols such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, and polypropylene glycol); mono-(meth)acrylate esters of monoalkyl ethers of glycols and oligoglycols; mono-(meth)acrylate esters of alkoxylated (e.g., ethoxylated and / or propoxylated) aliphatic alcohols (wherein the aliphatic alcohol may be straight chain, branched or alicyclic and may be a mono-alcohol, a di-alcohol or a polyalcohol, provided only one hydroxyl group of the alkoxylated aliphatic alcohol is esterified with (meth)acrylic acid); mono-(meth)acrylate esters of alkoxylated (e.g., ethoxylated and / or propoxylated) aromatic alcohols (such as alkoxylated phenols); caprolactone mono(meth)acrylates; and the like.

[0124] The following compounds are specific examples of mono(meth)acrylate monomers suitable for use in the composition: 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-hydroxy ethyl (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; glycidyl (meth)acrylate; isodecyl (meth)acrylate; lauryl (meth)acrylate; 2-phenoxyethyl (meth)acrylate; alkoxylated phenol (meth)acrylates; alkoxylated nonylphenol (meth)acrylates; cyclic trimethylolpropane formal (meth)acrylate; isobomyl (meth)acrylate; tricyclodecanemethanol (meth)acrylate; tert-butylcyclohexanol (meth)acrylate; trimethylcyclohexanol (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)acrylates; hydroxyl ethyl-butyl acid functionalized acrylic copolymers; 3-(2-hydroxyalkyl)oxazolidinone (meth)acrylates; and combinations thereof. In a preferred embodiment, the at least one ethylenically unsaturated co-monomer comprises a combination of methyl (meth)acrylate and n-butyl (meth)acrylate, more preferably methyl methacrylate and n-butyl acrylate.

[0125] In one embodiment, the (meth)acrylate monomer may comprise a (meth)acrylate monomer containing two or more (meth)acrylate groups per molecule.

[0126] Examples of suitable (meth)acrylate monomers containing two or more (meth)acrylate groups per molecule include acrylate and methacrylate esters of polyols. Such polyols may be fully or partially esterified (with (meth)acrylic acid, (meth)acrylic anhydride, (meth)acryloyl chloride or the like), provided they contain at least two (meth)acrylate functional groups per molecule.

[0127] Exemplary (meth)acrylate monomers containing two or more (meth)acryloyloxy groups per molecule may include 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; 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-l,4-dimethanol di(meth)acrylate; tricyclodecane dimethanol di(meth)acrylate; metallic di(meth)acrylates; modified metallic di(meth)acrylates; 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; as well as the alkoxylated (e.g., ethoxylated and / or propoxylated) derivatives thereof; and combinations thereof.

[0128] In a preferred embodiment, the acidic acrylic copolymer comprises a copolymer of acrylic acid, methyl methacrylate, and butyl acrylate in a ratio by weight of acrylic acid : methyl methacrylate : butyl acrylate of 20:20:60.

[0129] According to some embodiments, the optionally (meth)acrylate-functionalized acidic acrylic oligomer may be conveniently prepared by reacting the acidic acrylic copolymer with one or more ethylenically unsaturated epoxy compounds. Preferably, at least one acid group of the acidic acrylic copolymer is esterified with an unsaturated epoxy compound to form the optionally (meth)acrylate-functionalized acidic acrylic oligomer. Preferably, the unsaturated epoxy compound comprises a reaction product of acrylic or methacrylic acid or mixtures thereof with glycidyl ethers or esters, preferably a compound selected from the group consisting of glycidyl methacrylate, an acrylate of phenyl glycidyl ether, a methacrylate of phenyl glycidyl ether, and any combination thereof, most preferably glycidyl methacrylate.

[0130] According to some embodiments, the optionally (meth)acrylate-functionalized acidic acrylic oligomer may be conveniently prepared by reacting the acidic acrylic copolymer with one or more ethylenically unsaturated hydroxyl-functional compounds. Preferably, at least one acid group of the acidic acrylic copolymer is esterified with an unsaturated hydroxyl-functional compound to form the optionally (meth)acrylate- functionalized acidic acrylic oligomer.

[0131] According to some embodiments, the optionally (meth)acrylate-functionalized acidic acrylic oligomer is obtained by reacting the acidic acrylic copolymer with one or more compounds bearing at least one hydroxyl group and at least one (meth)acrylate group, preferably a compound selected from the group consisting of hydroxy ethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, glycerol diacrylate, glycerol dimethacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate, an acrylate of phenyl glycidyl ether, a methacrylate of phenyl glycidyl ether, and any combination thereof.

[0132] In a preferred embodiment, the hydroxy-functional compound is 2-hydroxyethyl acrylate (HEA) or 2-hydroxyethyl methacrylate (HEMA). Other suitable hydroxyfunctional compounds include 2- or 3 -hydroxylpropyl (meth)acrylate, an OH-terminated polycaprolactone including a terminal (meth)acrylate group, or other hydroxylfunctionalized (meth)acrylates and combinations thereof.

[0133] According to particular embodiments, the hydroxy-functional compound may be derived from hydroxyl terminated polyalkoxylates such as polyethylene glycol 200, polyethylene glycol 300, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 1450, polyethylene glycol 3350, polyethylene glycol 8000, polyethylene glycol 350 methyl ether, polyethylene glycol 550 methyl ether, polytetrahydrofuran, and mixtures thereof. According to some embodiments, the hydroxy-functional compound may be derived from a fatty alcohol. Non-limiting examples of such branched or straight chained fatty alcohols include tert-butyl alcohol, tert-amyl alcohol, 3 -methyl-3 -pentanol, 1- heptanol (enanthic alcohol), 1 -octanol (capryl alcohol), pelargonic alcohol (1 -nonanol), 1- decanol (decyl alcohol, capric alcohol), undecyl alcohol (1 -undecanol, undecanol, hendecanol), lauryl alcohol (dodecanol, 1 -dodecanol), tridecyl alcohol (1 -tridecanol, tridecanol, isotridecanol), myristyl alcohol (1 -tetradecanol), pentadecyl alcohol (1- pentadecanol, pentadecanol), cetyl alcohol (1 -hexadecanol), palmitoleyl alcohol (cis-9- hexadecen-l-ol), heptadecyl alcohol (1-n-heptadecanol, heptadecanol), stearyl alcohol (1- octadecanol), oleyl alcohol (1 -octadecenol), nonadecyl alcohol (1 -nonadecanol), arachidyl alcohol (1-eicosanol), heneicosyl alcohol (1-heneicosanol), behenyl alcohol (1 -docosanol), erucyl alcohol (cis-13-docosen-l-ol), lignoceryl alcohol (1-tetracosanol), cetyl alcohol (1- hexacosanol), 1-heptacosanol, montanyl alcohol, cluytyl alcohol, 1-octacosanol, 1- nonacosanolmyricyl alcohol, 1-triacontanol, 1-dotriacontanol, or geddyl alcohol (1- tetratriacontanol). Mixtures of any two or more of these are contemplated. In some embodiments, the hydroxy-functional compound may be derived from a long chain carboxylic acid comprising a terminal hydroxyl group. Non-limiting examples of such reactants are C2-C22 carboxylic acid aliphatic alcohols, such as 12 hydroxyl lauric acid. According to particular embodiments, the hydroxy-functional compound may be derived from alkoxylated fatty alcohols such as 12 molar ethoxylated tridecyl alcohol.

[0134] Other non-limiting examples of hydroxy-functional compounds include fatty alcohol alkoxylates. The alkoxylate moiety may comprise, consist of, or consist essentially of ethylene oxide (EO), propylene oxide (PO) or butylene oxide (BO) units or mixtures thereof. The alkoxylate moiety may also be present in the form of ethylene oxide / propylene oxide block copolymer. Fatty alcohol oxyalkylates may also comprise polyglycerolated fatty alcohols. The ethoxylated fatty alcohols, may be primary alcohols having from 8 to 22 carbon atoms, for example coconut, palm fat, palm kernel, tallow fat, lauryl, stearyl or oleyl alcohol. These may comprise from 1 to 80 EO (ethylene oxide) units per mole of alcohol, and the alcohol radical may be linear or may be methyl-branched in the 2-position, or may contain linear and methyl-branched radicals in a mixture, as is typically the case in oxo alcohol radicals. The ethoxylated alcohols may include, for example, Cl l alcohols having 3, 5, 7, 8 and 11 EO units, (C12-C15) alcohols having 3, 6, 7, 8, 10 and 13 EO units, (C14-C15) alcohols having 4, 7 and 8 EO units, (C16-C18) alcohols having 8, 11, 15, 20, 25, 50 and 80 EO units and mixtures thereof. The degrees of ethoxylation specified constitute statistical averages which may be an integer or a fraction for a specific product.

[0135] (Meth)acrylic Polymers

[0136] The curable composition of the present invention may optionally contain one or more (meth)acrylic polymers. However, such a (meth)acrylic polymer is not required and curable compositions which are free of any (meth)acrylic polymer are also contemplated by the present invention. As used herein, the term "(meth)acrylic polymer" means a polymer which comprises one or more (meth)acrylic monomers (in polymerized form) wherein the (meth)acrylic monomer(s) make up 50 wt% or more of the (meth)acrylic polymer. The term “(meth)acrylic monomer,” as used herein, means any type of polymerizable monomer containing one or more acrylic and / or methacrylic functional groups.

[0137] The presence of (meth)acrylic polymer in the curable composition can help to facilitate the dispersion and stabilization of the liquid zinc (meth)acrylate complex, both in the curable composition and a cured article prepared therefrom. Thus, including the (meth)acrylic polymer may lead to a homogeneous dispersion of the liquid zinc (meth)acrylate complex in the curable composition, which facilitates the formation of a homogeneous cured article prepared by curing the curable composition. An ideal homogeneous dispersion of the liquid zinc (meth)acrylate complex in a matrix has no agglomerates after the liquid zinc (meth)acrylate complex is combined with the monomer(s) and oligomer(s) (which may be generically referred to as “polymerizing organic substances”). Thus, a liquid curable composition comprising a (meth)acrylic polymer, a liquid zinc (meth)acrylate complex and a polymerizing organic substance may possess or exhibit a better dispersion of the liquid zinc (meth)acrylate complex than an analogous composition not comprising the (meth)acrylic polymer. Further, a liquid curable composition comprising a (meth)acrylic polymer, a liquid zinc (meth)acrylate complex and a polymerizing organic substance may be less viscous than an analogous composition not comprising the (meth)acrylic polymer.

[0138] The molecular weight of the (meth)acrylic polymer is not particularly limited and may be varied as may be needed or desired in order to impart certain characteristics or properties to the curable composition and / or cured articles prepared therefrom. The (meth)acrylic polymer may, for example, have a weight average molecular weight of from 2000 g / mol to 1,000,000 g / mol.

[0139] In a first embodiment, the (meth)acrylic polymer may have a weight average molecular weight (Mw) of at least 100,000 g / mol, more than 100,000 g / mol, more than 105,000 g / mol, more than 110,000 g / mol, more than 120,000 g / mol, more than 130,000 g / mol, or more than 140,000 g / mol.

[0140] The (meth)acrylic polymer may have a weight average molecular weight (Mw) below 1,000,000 g / mol, below 900,000 g / mol, below 800,000 g / mol, below 700,000g / mol, below 600,000 g / mol, below 550,000 g / mol, below 500,000 g / mol, or below 450,000 g / mol.

[0141] For example, the weight average molecular weight (Mw) of the (meth)acrylic polymer (PI), according to the first preferred embodiment, is preferably between 100,000 g / mol and 1,000,000 g / mol, preferably between 105,000 g / mol and 900,000 g / mol, more preferably between 110,000 g / mol and 800,000 g / mol, advantageously between 120,000 g / mol and 700,000 g / mol, more advantageously between 130,000 g / mol and 600,000 g / mol, and most advantageously between 140,000 g / mol and 500,000 g / mol.

[0142] In a second embodiment, the (meth)acrylic polymer has a weight average molecular weight Mwof less than 100,000 g / mol, less than 90,000 g / mol, more less than 80,000 g / mol, less than 70,000 g / mol, less than 60,000 g / mol, less than 50,000 g / mol, or less than 40,000 g / mol.

[0143] In the second embodiment, the (meth)acrylic polymer may have a weight average molecular weight (Mw) above 2000 g / mol, above 3000 g / mol, above 4000 g / mol, above 5 000 g / mol, above 6000 g / mol, above 6500 g / mol, above 7000 g / mol, above 10,000 g / mol, or above 12,000 g / mol.

[0144] The weight average molecular weight (Mw) of the (meth)acrylic polymer in the second embodiment may be between 2000 g / mol and 100,000 g / mol, between 3000 g / mol and 90,000 g / mol, between 4 000 g / mol and 80,000 g / mol, between 5000 g / mol and 70,000 g / mol, between 6000 g / mol and 50,000 g / mol, orbetween 10,000 g / mol and 40,000 g / mol.

[0145] According to certain embodiments of the invention, the (meth)acrylic polymer may comprise at least 50 wt%, at least 60 wt%, or at least 70 wt% of one or more monomers selected from the group consisting of Ci to C12 alkyl (meth)acrylates. For example, the (meth)acrylic polymer may comprise at least 50 wt%, at least 60 wt%, at least 70 wt% or at least 80% of one or more monomers chosen from Ci to C4 alkyl methacrylate monomers, Ci to Cs alkyl acrylate monomers and mixtures thereof.

[0146] In certain embodiments, the glass transition temperature (Tg) of the (meth)acrylic polymer is 20°C or higher, e.g., between 30°C and 150°C. The glass transition temperature of the (meth)acrylic polymer may, for example, be between 40°C and 150°C, between 45°C and 150°C, or between 50°C and 150°C.

[0147] According to certain embodiments, the (meth)acrylic polymer is not crosslinked. According to other embodiments, the (meth)acrylic polymer is a thermoplastic polymer. The (meth)acrylic polymer may be a homopolymer or a copolymer, wherein “copolymer” refers to a polymer containing two or more different monomers in polymerized form. The term “thermoplastic polymer” as used herein means a polymer that turns to a liquid or becomes more liquid or less viscous when heated and that can take on new shapes by the application of heat and pressure. The (meth)acrylic polymer, in certain embodiments, is not grafted on any other polymer or polymers, or at least a portion of the (meth)acrylic polymer is not granted on any other polymer or polymers.

[0148] In a first embodiment, the (meth)acrylic polymer comprises (in polymerized form) from 50 wt% to 100 wt% methyl methacrylate, from 80 wt% to 100 wt% methyl methacrylate, or from 80 wt% to 99.8 wt% methyl methacrylate and from 0.2 wt% to 20 wt% of a Ci to Cs alkyl acrylate monomer. The Ci to Cs alkyl acrylate monomer may be selected from the group consisting of methyl acrylate, ethyl acrylate and butyl acrylate, according to certain non-limiting embodiments.

[0149] In a second embodiment, the (meth)acrylic polymer comprises (in polymerized form) between 0 wt% and 50 wt% of one or more functional monomers. For example, the (meth)acrylic polymer may comprise between 0 wt% and 30 wt%, between 1 wt% and 30 wt%, between 2 wt% and 30 wt%, between 3 wt% and 30 wt%, between 5 wt% and 30 wt%, or between 5 wt% and 30 wt% of the functional monomer(s).

[0150] The functional monomer of the second preferred embodiment may be a (meth)acrylic monomer. The functional monomer(s) may have the formula (1) or (2):

[0151] ( 1 )

[0152] (2 ) wherein in both formulas (1) and (2), Ri is selected from H or CH3; and in formula (1) Y is O, R5 is H or an aliphatic or aromatic radical having at least one atom that is not C or H; and in formula (2) Y is N and R4 and R3 are independently selected from H or an aliphatic or aromatic radical.

[0153] Preferably the functional monomer(s) is or are selected from the group consisting of glycidyl (meth)acrylate; (meth)acrylic acid; (meth)acrylamides such as, for example, dimethylacrylamide; 2-methoxyethyl (meth)acrylate; 2-aminoethyl (meth)acrylates (which may optionally be quatemized; (meth)acrylate monomers comprising a phosphonate or phosphate group; alkyl imidazolidinone (meth)acrylates, and polyethylene glycol (meth) acrylates and combinations thereof. Preferably, the polyethylene glycol group of a polyethylene glycol (meth)acrylate has a number average molecular weight ranging from 400g / mol to 10,000 g / mol.

[0154] According to certain embodiments of the invention, the (meth)acrylic polymer does not contain any functional groups capable of participating in the curing / polymerization which takes place when the curable composition is cured. In such embodiments, the (meth)acrylic polymer may be regarded as non-reactive. In accordance with certain embodiments of the invention, the (meth)acrylic polymer may be soluble at 25°C in the organic polymerizing substances (the mixture of monomer(s) and oligomer(s) present in the curable composition. That is, the organic polymerizing substances function as a solvent for the (meth)acrylic polymer(s). Thus, the combination of (meth)acrylic polymer(s), monomer(s) and oligomer(s) may be a homogeneous (single phase) liquid at 25°C. “Soluble” means that within a certain time the (meth)acrylic polymer(s) when contacted with the polymerizing organic substances dissolve and a solution of the (meth)acrylic polymer(s) in the polymerizing organic substances is obtained. The solubility of the (meth)acrylic polymer(s) in the polymerizing organic substances can be simply tested by mixing the materials at 25°C under agitation and visually inspecting the mixture.

[0155] If present in the curable composition, the (meth)acrylic polymer may be included in any suitable amount such as up to 80%, up to 70%, up to 60%, up to 50%, up to 40%, up to 30%, up to 20%, up to 10%, or up to 5% by weight based on the total weight of the curable composition.

[0156] Initiator

[0157] The curable compositions described herein include at least one initiator and are curable with radiant energy (actinic radiation). An initiator may be considered any type of substance that, upon exposure to radiation (e.g., actinic radiation), forms species that initiate the reaction and curing of polymerizing monomers and / or oligomers present in the curable composition, such as monomeric polymerizing monomers and / or oligomers as well as oliogomeric polymerizing monomers and / or oligomers. Suitable initiators include both free radical photoinitiators as well as cationic photoinitiators and combinations thereof. The photoinitiator should be selected so that it is susceptible to activation by photons of the wavelength associated with the actinic radiation intended to be used to cure the curable composition.

[0158] Free radical polymerization initiators are substances that form free radicals when irradiated. The use of free radical photoinitiators is especially preferred. Non-limiting types of free radical photoinitiators suitable for use in the curable compositions of the present invention include, for example, benzoins, benzoin ethers, acetophenones, benzyl, benzyl ketals, anthraquinones, phosphine oxides, a-hydroxyketones, phenylglyoxylates, a- aminoketones, benzophenones, thioxanthones, xanthones, acridine derivatives, phenazene derivatives, quinoxaline derivatives and triazine compounds. Suitable photoinitiators include those capable of generating free radicals when exposed to the requisite radiation, such as UV light. In an exemplary embodiment, the photoinitiators include acyl phosphine oxides (e.g., Irgacure® 819, Lucirin® TPO and Lucirin® TPO-L); benzil ketals (e.g., Irgacure 651); alpha-hydroxy phenyl ketones e.g., Irgacure 184 or Darocur 1173) or mixtures thereof.

[0159] When the curable composition contains polymerizing monomers and / or oligomers containing polymerizable (reactive) ethylenically unsaturated functional groups such as (meth)acrylate functional groups, the use of free radical photoinitiators is especially preferred. Non-limiting types of free radical photoinitiators suitable for use in the curable compositions of the present invention include, for example, benzoins, benzoin ethers, acetophenones, benzyl, benzyl ketals, anthraquinones, phosphine oxides, a- hydroxyketones, phenylglyoxylates, a-aminoketones, benzophenones, thioxanthones, xanthones, acridine derivatives, phenazene derivatives, quinoxaline derivatives and triazine compounds. Examples of particular suitable free radical photoinitiators include, but are not limited to, 2-methylanthraquinone, 2-ethylanthraquinone, 2-chloroanthraquinone, 2- benzyanthraquinone, 2-t-butylanthraquinone, l,2-benzo-9,10-anthraquinone, benzyl, benzoins, benzoin ethers, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, alpha-methylbenzoin, alpha-phenylbenzoin, Michler’s ketone, acetophenones such as 2,2-dialkoxybenzophenones and 1 -hydroxyphenyl ketones, benzophenone, 4,4’ -bis-(di ethylamino) benzophenone, acetophenone, 2,2- diethyloxyacetophenone, diethyloxyacetophenone, 2-isopropylthioxanthone, thioxanthone, diethyl thioxanthone, 1,5-acetonaphthylene, ethyl-p-dimethylaminobenzoate, benzil ketone, a-hydroxy keto, 2,4,6-trimethylbenzoyldiphenyl phosphine oxide, benzyl dimethyl ketal, 2,2-dimethoxy-l,2-diphenylethanone, 1 -hydroxy cylclohexyl phenyl ketone, 2- methyl- 1 -[4-(m ethylthio) phenyl]-2-morpholinopropanone- 1 , 2-hydroxy-2-methyl- 1 - phenyl-propanone, oligomeric a-hydroxy ketone, benzoyl phosphine oxides, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl-4-dimethylamino benzoate, ethyl(2,4,6-trimethylbenzoyl)phenyl phosphinate, anisoin, anthraquinone, anthraquinone- 2-sulfonic acid, sodium salt monohydrate, (benzene) tri carbonyl chromium, benzil, benzoin isobutyl ether, benzophenone / 1 -hydroxy cyclohexyl phenyl ketone, 50 / 50 blend, 3, 3', 4, d'benzophenonetetracarboxylic dianhydride, 4-benzoylbiphenyl, 2-benzyl-2- (dimethylamino)-4'-morpholinobutyrophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'- bis(dimethylamino)benzophenone, camphorquinone, 2-chlorothioxanthen-9-one, dibenzosub er enone, 4,4'-dihydroxybenzophenone, 2,2-dimethoxy-2-phenylacetophenone, 4-(dimethylamino)benzophenone, 4,4'-dimethylbenzil, 2,5-dimethylbenzophenone, 3,4- dimethylbenzophenone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide / 2-hydroxy-2- methylpropiophenone, 50 / 50 blend, 4'-ethoxyacetophenone, 2,4,6- trimethylbenzoyldiphenylphophine oxide, phenyl bis(2,4,6-trimethyl benzoyl)phosphine oxide, ferrocene, 3'-hydroxyacetophenone, 4'-hydroxyacetophenone, 3- hydroxybenzophenone, 4-hydroxybenzophenone, 1 -hydroxy cyclohexyl phenyl ketone, 2- hydroxy-2-methylpropiophenone, 2-methylbenzophenone, 3 -methylbenzophenone, methybenzoylformate, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone, phenanthrenequinone, 4'-phenoxyacetophenone, (cumene)cyclopentadienyl iron(ii) hexafluorophosphate, 9, 10-di ethoxy and 9,10-dibutoxyanthracene, 2-ethyl-9,10- dimethoxyanthracene, thioxanthen-9-one and combinations thereof.

[0160] Suitable cationic photoinitiators include any type of photoinitiator that, upon exposure to radiation such as actinic radiation, forms cations (e.g., Brbnsted or Lewis acids) that initiate the reaction of the monomeric and (if present) oligomeric polymerizing monomers and / or oligomers in the curable composition. For example, a cationic photoinitiator may be comprised of a cationic portion and an anionic portion. The cationic portion of the photoinitiator molecule can be responsible for the absorption of UV radiation while the anionic portion of the molecule becomes a strong acid after UV absorption. Suitable cationic photoinitiators include, for example, onium salts with anions of weak nucleophilicity, such as halonium salts, iodonium salts (e.g., diaryliodonium salts such as bis(4-t-butylphenyl) iodonium perfluoro- 1 -butane sulfonate) or sulfonium salts (e.g., triarylsulfonium salts such as triarylsulfonium hexafluoroantimonate salts); sulfoxonium salts; and diazonium salts. Metallocene salts are another type of suitable cationic photoinitiator.

[0161] The amount of photoinitiator may be varied as may be appropriate depending upon the photoinitiator(s) selected, the amounts and types of polymerizing monomers and / or oligomers (monomeric and oligomeric) present in the curable composition, the radiation source and the radiation conditions used, among other factors. Typically, however, the amount of photoinitiator may be from 0.05% to 10%, preferably 0.05 to 5%, more preferably 0.1% to 2%, and most preferably 1% to 2% by weight, based on the total weight of the curable composition. The curable compositions of the present invention may optionally contain one or more additives instead of or in addition to the above-mentioned ingredients. Such additives include, but are not limited to, solvents, adhesion promoters, antioxidants / photostabilizers, light blockers / absorbers, polymerization inhibitors, foam inhibitors, flow or leveling agents, colorants, pigments, dispersants (wetting agents, surfactants), slip additives, fillers, chain transfer agents, thixotropic agents, rheology modifiers, matting agents, impact modifiers (other than the liquid zinc (meth)acrylate complexes and oligomeric polymerizing monomers and / or oligomers already mentioned), thermoplastics such as acrylic resins that do not contain any free radical-polymerizable functional groups, waxes or other various additives, including any of the additives conventionally utilized in the substrate coating art.

[0162] To protect against premature gelling or curing of the curable composition, particularly in the presence of oxygen or other oxidant, one or more antioxidants may be included in the curable composition. Any of the antioxidants known in the art may be utilized, including for example phenol-based antioxidants, phosphorus-based antioxidants, quinone-type antioxidants and combinations thereof.

[0163] Examples of suitable phenol-based antioxidants may include hindered phenol-type antioxidants such as hexamethylene bis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid amide], 4,4'-thio bis(6-tert-butyl-m-cresol), 2,2'-methylene bis(4-methyl-5-tert- butylphenol), 2,2'-methylene bis(4-ethyl-6-tert-butylphenol), bis[3,3-bis(4-hydroxy-3-tert- butylphenyl)butyric acid]glycol ester, 2,2'-ethylidene bis(4,6-di-tert-butylphenol), 2,2' - ethylidene bis(4-sec-butyl-6-tert-butylphenol), 1, l,3-tris(2-methyl-4-hydroxy-5-tert- butylphenyl)butane, bis[2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5- methylbenzyl)phenyl]terephthalate, l,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6- trimethylbenzene, 1,3,5 -tris [(3 , 5 -di-tert-butyl-4- hydroxyphenyl)propionyloxyethyl]isocyanurate, tetrakis[methylene-3-(3,5-di-tert-butyl-4- hydroxyphenyl) propionate] methane, 2-tert-butyl-4-methyl-6-(2-acryloyloxy-3-tert-butyl- 5-methylbenzyl)phenol, 3,9-bis[l,l-dimethyl-2-{(3-tert-butyl-4-hydroxy-5- methylphenyl)propionyloxy}ethyl]-2,4,8, 10-tetraoxaspiro[5.5]undecane, triethylene glycol bis[(3-tert-butyl-4-hydroxy-5-methylphenyl)propi onate], and n-octadecyl-3-(4'-hydroxy- 3',5'-di-tert-butylphenyl)butane. Butylated hydroxy toluene (BHT) is an example of a preferred antioxidant. Examples of suitable phosphorus-based antioxidants may include phosphites, phosphonites and the like such as trisnonylphenyl phosphite, tris(2,4-di-tert- butylphenyl)phosphite, tris[2-tert-butyl-4-(3-tert-butyl-4-hydroxy-5-methylphenylthio)-5- methylphenyl]phosphite, tridecyl phosphite, octyldiphenyl phosphite, di(decyl)monophenyl phosphite, di(tridecyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, di(nonylphenyl)pentaerythritol diphosphite, bis(2,4-di-tert- butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4- methylphenyl)pentaerythritol diphosphite, bis(2,4,6-tri-tert-butylphenyl)pentaerythritol diphosphite, tetra(tridecyl)isopropylidene diphenol diphosphite, tetra(tridecyl)-4,4'-n- butylidene bis(2-tert-butyl-5-methylphenol)diphosphite, hexa(tridecyl)-l,l,3-tris(2-methyl- 4-hydroxy-5-tert-butylphenyl)butane triphosphite, tetrakis(2,4-di-tert- butylphenyl)biphenylene diphosphonite, 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10- oxide, 2,2'-methylene bis(4-methyl-6-tert-butylphenyl)-2-ethylhexyl phosphite, and 4-[3- [(2,4,8,10-tetra-tert-butyldibenzo[d,f][l,3,2]dioxaphosphepin)-6-yloxy]propyl]-2-methyl- 6-tert-butylphenol .

[0164] Quinone-type antioxidants, such as the mono methyl ether of hydroquinone (MEHQ), may also be used. Phenothiazine (RTZ) and vitamin E are examples of other suitable antioxidants useful in the present invention.

[0165] Typically, one or more antioxidants may be included in the curable composition in a total amount of up to 4% by weight, e.g., 0.05 to 2% by weight, based on the weight of the curable composition.

[0166] Advantageously, the curable compositions utilized in the present invention may be formulated to be solvent-free, i.e., free of any non-reactive volatile substances (substances having a boiling point at atmospheric pressure of 150°C or less). For example, the curable compositions may contain little or no non-reactive solvent, e.g., less than 10% or less than 5% or less than 1% or even 0% non-reactive solvent, based on the total weight of the curable composition. In the context of the present invention, “non-reactive” refers to a substance that does not react when exposed to actinic radiation, i.e., a non-polymerizing substance. Such solvent-less or low-solvent compositions may be formulated using various components, including for example low viscosity reactive diluents (such as monomeric polymerizing monomers and / or oligomers), which are selected so as to render the curable composition sufficiently low in viscosity, even without solvent being present, that the curable composition can be easily applied at a suitable application temperature to a substrate surface such as the surface of a substrate of a subject.

[0167] However, in other embodiments, the curable composition which is used does contain some amount of non-reactive solvent, in particular some amount of volatile non- reactive solvent (having a boiling point at atmospheric pressure of not more than 150°C). As an example, if the curable composition is to be formulated for use as a relatively low viscosity top coat, base coat, color coat or substrate polish, one or more non-reactive solvents may be included. For example, the curable composition may be comprised of at least 0.5, at least 1, at least 5, or at least 10% by weight non-reactive solvent based on the total weight of the curable composition. The curable composition could comprise not more than 50, not more than 25, or not more than 15% by weight non-reactive solvent based on the total weight of the curable composition. The amount of non-reactive solvent may be adjusted to achieve a target viscosity value, as the non-reactive solvent will generally reduce the viscosity of a curable composition. Two or more non-reactive solvents may be used in combination. Suitable non-reactive solvents include esters (such as ethyl acetate and butyl acetate), ethers, ketones, glycol ethers, alcohols, hydrocarbons and combinations thereof.

[0168] Suitable solvents are any solvents that will dissolve all other components in the curable liquid zinc (meth)acrylate complex composition and include aliphatic or aromatic hydrocarbons (e.g., hexane, toluene or xylene), alcohols (e.g., ethanol or propylene glycol), esters (e.g., ethyl acetate, n-butyl acetate), ketones (e.g., acetone, methyl isobutyl ketone or methyl ethyl ketone) and ethers (e.g., propylene glycol methyl ether or dimethoxy ethane). In other embodiments, however, the curable compositions of the present invention may be formulated to be solvent-free, i.e., free of any non-reactive volatile substances (substances having a boiling point at atmospheric pressure of 150°C or less). For example, the curable liquid zinc (meth)acrylate complex compositions of the present invention may contain little or no non-reactive solvent, e.g., less than 10% or less than 5% or less than 1% or even 0% of a non-reactive solvent, based on the total weight of the curable composition. In a preferred embodiment, the liquid zinc (meth)acrylate complex compositions of the present invention may be substantially free of water, e.g., less than 10% or less than 5% or less than 1% or even 0% of a water, based on the total weight of the curable composition.

[0169] Any of the stabilizers known in the art related to (meth)acrylate-functionalized compounds may be utilized in the present invention. Quinones represent a particularly preferred type of stabilizer which can be employed in the context of the present invention. As used herein, the term "quinone" includes both quinones and hydroquinones as well as ethers thereof such as monoalkyl, monoaryl, monoaralkyl and bi s(hydroxy alkyl) ethers of hydroquinones. Hydroquinone monomethyl ether is an example of a suitable stabilizer which can be utilized.

[0170] The concentration of stabilizer in the curable composition will vary depending upon the particular stabilizer or combination of stabilizers selected for use and also on the degree of stabilization desired and the susceptibility of components in the curable compositions towards degradation in the absence of stabilizer. Typically, however, the curable composition is formulated to comprise from 50 to 5000 ppm stabilizer.

[0171] Formulation of the Curable Composition

[0172] The relative weight proportions of the liquid zinc (meth)acrylate complex, the at least one polymerizing monomer and / or oligomer, and the at least one initiator are not believed to be particularly critical and may be varied as desired based on the particular components selected and the characteristics sought in the curable composition and cured articles obtained therefrom. For example, the curable composition in certain embodiments may comprise 5 to 45 wt % of the liquid zinc (meth)acrylate complex, 5 to 60 wt % of the at least one polymerizing monomer and / or oligomer, and 0.1 to 10 wt % of the at least one initiator, wherein the weight of the liquid zinc (meth)acrylate complex, the at least one polymerizing monomer and / or oligomer, and the at least one initiator equals 100% in total (meaning that the aforementioned wt % ranges for each of the liquid zinc (meth)acrylate complex, the at least one polymerizing monomer and / or oligomer, and the at least one initiator is based on the combined weights of those components, not the total weight of the curable composition which may contain components in addition to the liquid zinc (meth)acrylate complex, the at least one polymerizing monomer and / or oligomer, and the at least one initiator).

[0173] According to preferred embodiments, the components of the curable composition are selected so that the curable composition is liquid at least in the temperature range between 0°C and 60°C. As used in this context, the term “liquid” does not preclude the possibility that some portion of the curable composition may be present in the form of small, well-dispersed particles in an otherwise liquid matrix. In certain embodiments of the invention, the curable composition is a liquid at 25°C. For example, the curable composition may be a flowable and / or self-levelling liquid at 25°C. In other embodiments, however, the curable composition may be a gel at 25°C. Such a gel may be non-flowable.

[0174] The viscosity of the curable composition at 25°C may be varied widely, depending upon the intended end use application as discussed in more detail below. For example, the viscosity of the curable composition at 25°C may range from 100 cps to 5,000,000 cps.

[0175] In various embodiments of the invention (for example, where the curable composition is intended for use as a UV gel polish, base coat, color coat or top coat), the curable compositions described herein are formulated to have a relatively low viscosity at ambient or room temperature. For example, the viscosity of the curable composition may be selected or adjusted, by varying the components present and their relative ratios, to provide a viscosity at 25°C which is not more than 100,000 cps, not more than 50,000 cps, not more than 25,000 cps, or not more than 10,000 cps as measured by a Brookfield DV3T Cone and Plate Rheometer with measurements conducted at 25°C on 0.5 mL samples using a CPE-52Z cone. The viscosity at 25°C could, for example, be at least 100 cps or at least 500 cps.

[0176] However, in other embodiments of the invention, the curable compositions described herein are formulated to have a relatively high viscosity at ambient or room temperature. Such high viscosity curable compositions may be of interest where it is intended to be applied to a substrate surface and then sculpted (i.e., a builder gel, sculpting gel, or substrate extension). For example, the viscosity of the curable composition may be selected or adjusted, by varying the components present and their relative ratios, to provide a viscosity at 25°C which is at least 200,000 cps, at least 300,000 cps, or at least 400,000 cps, as measured by a Brookfield DV3T Cone and Plate Rheometer with measurements conducted at 25°C on 0.5 mL samples using a CPE-52Z cone. At the same time, the viscosity should not be so high that the curable composition becomes difficult to apply and / or shape on a substrate surface. The viscosity at 25°C could, for example, be not greater than 5,000,000 cps or not greater than 4,000,000 cps.

[0177] The viscosity and other rheological properties of the curable composition may be selected such that when a portion of the curable composition is applied onto a substrate surface, it does not move easily until it is pushed into a desired shape (sculpted) by a manicurist tool, such as a brush, pusher and / or spatula. The pushing and sculpting of the curable composition into a desired shape may be done neat, or it may be done with the aid of a low viscosity liquid (such as a non-reactive solvent and / or a reactive diluent, such as a (meth)acrylate-functionalized monomer) which lowers, at least locally, the viscosity of the curable composition. According to advantageous embodiments of the invention, when the curable composition is either in neat form or is admixed with such a liquid (in limited amounts), the curable composition remains firm (but shapable) and does not run. An operator, such as a substrate technician, may optionally control the viscosity through the application of such a suitable liquid, which may be done only in selected areas of the portion of curable composition on the substrate surface, until the curable composition is cured by exposure to actinic radiation (e.g., UV light).

[0178] Cured composition, coated substrate and its method of making

[0179] The compositions useful in the methods of the invention may be used to obtain a cured composition. In certain embodiments, the cured liquid zinc (meth)acrylate complex has a number average molecular weight of from 500 to 50,000, preferably from 800 to 15,000, more preferably 1,000 to 10,000.

[0180] The cured composition may be a cured film or coating, a cured primer or ink, or a cured inkjet formulation.

[0181] The invention also relates to a substrate coated with a cured composition useful in the methods according to the invention. Such substrate may be referred to as an article.

[0182] The invention also relates to a method for making an article useful in the methods according to the invention, comprising: applying the curable composition to a substrate; and curing the composition.

[0183] The substrate may be any suitable substrate, such as metal, glass, plastic (e.g., thermoplastics such as polyolefins, polycarbonate, acrylonitrile butadiene styrene (ABS), and blends thereof), composites, wood, carbon, fiberglass, nonwovens, ceramics, concrete, stone and composites thereof. In a preferred embodiment, the substrate is plastic.

[0184] The curing of the composition of the present invention may be carried out by any suitable method, such as free radical, thermal, electron beam, redox, Michael addition, cationic and / or anionic polymerization. One or more initiators, such as a free radical initiator (e.g., a photoinitiator, a peroxide initiator) may be present in the composition. In general, the curing step may comprise one of: (1) exposing the composition to UV light or visible light; (2) exposing the composition to an electron beam radiation; (3) initiating polymerization through the use of a redox-generated radical; or (4) initiating polymerization through the use of a thermally-generated radical. Curing may be accelerated or facilitated by supplying energy to the composition, such as by exposing the composition to a radiation source, such as visible light or UV energy, and / or electron beam radiation. In an exemplary embodiment, the composition may be cured with UVC, UVB, UVA energy, and / or visible light. In an exemplary embodiment, the composition is cured with a UV light source utilizing UVA / UVB or UVA only and involves essentially no UVC radiation. In an exemplary embodiment, the composition is cured with high energy radiation, ranging from 0.01 to 10 W / cm2. Possible light sources include, but are not limited to, natural outdoor light, black light, fluorescent light, or high pressure mercury light.

[0185] In an exemplary embodiment, the curing is conducted by exposing the composition to ultraviolet radiation provided by one or more UV lamps delivering an irradiance level of 0.01 to 10 W / cm2, such as 1 to 10 W / cm2, for a time between 1 second and 30 minutes, such as between 1 second and 10 minutes. In another embodiment, the curing is conducted by exposing the composition to e-beam radiation. In another embodiment, the curing is conducted by exposing the composition to heat in the presence of a peroxide initiator (thermal curing). In another embodiment, the curing occurs via redox polymerization which is a two-part process involving a peroxide initiator (e.g., as hydrogen peroxide, benzoyl peroxide or t-butyl hydroperoxide) as a first part and a reducing agent (e.g., a tertiary amine such as N,N-dimethylaniline, N-(4-methoxyphenyl)pyrrolidine and N- phenyldiethanol amine, sodium sulfite, sodium metabisulfite).

[0186] The curable (meth)acrylate-containing compositions of the present invention are particularly well suited to being cured using LED (Light Emitting Diode) curing (e.g., UV LED curing, using radiation from a UV LED device) and for use in high speed applications (such as coatings).

[0187] Prior to curing, the curable acidified anhydride oligomer containing composition may be applied to at least part of the surface of a substrate in any known conventional manner, for example, by spraying, by brush, by sponge, by knife coating, by roller coating, by casting, by drum coating, by dipping, by curtain coating, by screen printing or by other methods of image transfer, by coating transfer, and the like and combinations thereof. Indirect application using a transfer process may also be used. In an embodiment, the curable acidified anhydride oligomer containing composition may be applied directly to a substrate, either as a primer or other coating layer, or over one or more of a primer, a basecoat system or other suitable layers in order to achieve the desired final appearance and properties. For example, the curable composition can be applied over a waterborne basecoat or a solvent-borne basecoat.

[0188] A substrate may be any commercially relevant substrate, such as a high surface energy substrate or a low surface energy substrate, such as a metal substrate or plastic substrate, respectively. The substrates may comprise metal, glass, plastics (e.g., thermoplastics such as polyolefins, polycarbonate, acrylonitrile butadiene styrene (ABS), and blends thereof), composites, wood, carbon, fiberglass, nonwovens, ceramics, concrete, stone and combinations thereof. Depending on the particular application, a suitable dry film thickness ranges from 5 to 200 microns. For 3D printing applications or electronics applications, the film may be thicker than 200 microns.

[0189] Method a Cured Composition

[0190] The invention also relates to a method for recycling a substrate coated with a cured primer, coating, or ink composition, wherein the cured composition is obtained by curing a curable primer, ink, or coating composition comprising: at least one liquid zinc (meth)acrylate complex, the complex comprising a ligand coordinated with zinc; at least one polymerizing monomer and / or oligomer; and at least one initiator, the method comprising the steps of contacting the substrate coated with the cured primer, coating, or ink composition with a recycling solution having a pH sufficient to delaminate the cured primer, coating, or ink composition from the substrate. In another embodiment, the method of the invention further comprises retrieving from the recycling solution the substrate substantially free from the cured primer, coating, or ink composition.

[0191] According to certain embodiments, the method of the invention may be used to delaminate a cured primer, coating, or ink composition from a substrate that comprises paper, fabric, metal, glass, plastic (e.g., thermoplastics such as polyolefins, polycarbonate, acrylonitrile butadiene styrene (ABS), and blends thereof), composites, wood, carbon, fiberglass, nonwovens, ceramics, concrete, and composites thereof. According to certain embodiments of the inventive method, the substrate comprises a plastic, preferably polyethylene terephthalate.

[0192] The invention also relates to a method for removing a cured primer, ink, or coating from a substrate, wherein the method for removing the cured primer, ink, or coating comprises: immersing a substrate coated with a cured composition according to the invention with a soaking solution having a pH sufficient to partially or fully delaminate the cured primer, ink, or coating from the substrate; wherein, if the immersing step only partially delaminates the cured primer, ink, or coating from the substrate thereby leaving a portion of the cured primer, ink, or coating from the substrate attached to the substrate, then the method further comprises manually removing from the substrate the portion of the cured primer, ink, or coating attached to the substrate while the substrate is still present in the soaking solution or, alternatively, after the substrate is removed from the soaking solution.

[0193] The recycling / soaking solution described herein causes release (delamination) of the cured liquid zinc (meth)acrylate complexes of the invention (and the compositions, films, etc. in which they are present) from the substrates to which they are attached, resulting in effective removal of the cured coating from the substrate. In certain embodiments, delamination occurs within 10 minutes of exposure to the recycling / soaking solution at a solution temperature of 25°C to 85°C.

[0194] In an exemplary embodiment, the recycling / soaking solution is an aqueous solution of a base (such as an inorganic base or an organic base). Other components may include, but are not limited to, surfactants and defoamers. The amount of the recycling / soaking solution used to effect release (delamination) of the cured acidic acid functionalized acrylic copolymers is not particularly limited and may be present in a large stoichiometric excess relative to the cured liquid zinc (meth)acrylate complex.

[0195] Suitable inorganic bases for use in the recycling / soaking solution include alkali metal and alkaline earth metal bicarbonates or carbonates (e.g., sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, calcium bicarbonate, calcium carbonate) and alkali metal and alkaline earth metal hydroxides (e.g., sodium hydroxide, potassium hydroxide, calcium hydroxide). Suitable organic bases for use in the recycling / soaking solution include ammonia, amines (e.g., alkyl amines, such as methylamine and ethylamine, isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, diethanolamine, ethanolamine, 2-dimethylaminoethanol, 2- diethylaminoethanol, dicyclohexylamine, etc.). Other suitable organic bases include pyridine, imidazole, benzimidazole, guanidine, histidine, phosphazene bases, and hydroxides of quaternary ammonium cations.

[0196] In an exemplary embodiment, the pH of the recycling / soaking solution is basic - i.e., has a pH greater than 7. In an exemplary embodiment, the pH is greater than 7 and less than 13, such as greater than 7 and less than 12, such as greater than 7 and less than 11, such as greater than 7 and less than 10, such as greater than 7 and less than 9. The pH will depend on the content of the liquid zinc (meth)acrylate complex in the cured composition to be delaminated; with increasing content of liquid zinc (meth)acrylate complex, a recycling solution or soaking solution with a lower pH can be used and have the same effect as a recycling solution or soaking solution having a higher pH on a cured composition having a lower content of liquid zinc (meth)acrylate complex.

[0197] Ease of delamination is dependent on the ease with which the recycling / soaking solution is able to permeate the composition containing the cured liquid zinc (meth)acrylate complex, which is impacted by physical properties of the composition, including the degree of cross-linking, glass transition temperature (Tg), and its hydrophilicity. Triggered removability of these coatings is influenced by four main conditions 1) crosslink density of the composition 2) number of triggered functional groups within the composition 3) removal time and 4) removal temperature. The crosslink density is important because if the composition is too highly crosslinked, the remover will not be able to penetrate through the film and trigger removability via a swelling mechanism. In addition, there has to be a certain number of acidic functional groups present in the film that can allow for enough swelling. The removal time is important because it allows the aqueous based remover to penetrate the film and temperature of the remover during removal can help with softening of the film to increase penetration and mobility. Regardless of the ease of removability of a composition containing a liquid zinc (meth)acrylate complex of the present invention, the inclusion of the liquid zinc (meth)acrylate complex of the invention in such a composition has been found to make such removability easier.

[0198] The following test conditions may be used, in one aspect of the invention, as a standard for achieving complete delamination of a primer, ink, or coating composition containing the cured liquid zinc (meth)acrylate complex from the substrate to which the primer, ink, or coating composition is attached: Upon exposure of the coated substrate to a 2% sodium hydroxide (NaOH) solution at 25°C to 85°C for 10 minutes, complete delamination of the coating from the substrate occurs. Utilizing the liquid zinc (meth)acrylate complex of the present invention can achieve this in certain formulations (e.g., ones that do not increase the cross link density and utilize a sufficient amount of the liquid zinc (meth)acrylate complex of the invention) and in other formulations, utilizing the liquid zinc (meth)acrylate complexof the invention increases the extent of delamination under such conditions compared to a similar formulation that does not contain a liquid zinc (meth)acrylate complex of the present invention.

[0199] Aspects of the Invention

[0200] Certain, non-limiting aspects of the invention may be summarized as follows:

[0201] Aspect 1 : A method for recycling a substrate coated with a cured primer, coating, or ink composition, wherein the cured composition is obtained by curing a curable primer, ink, or coating composition comprising: at least one liquid zinc (meth)acrylate complex, the complex comprising a ligand coordinated with zinc; at least one polymerizing monomer and / or oligomer; and at least one initiator, the method comprising the steps of: contacting the substrate coated with the cured primer, coating, or ink composition with a recycling solution having a pH sufficient to delaminate the cured primer, coating, or ink composition from the substrate.

[0202] Aspect 2: The method of Aspect 1, wherein the ligand comprises at least one ethylenically unsaturated carboxylic acid.

[0203] Aspect 3 : The method of Aspect 2, wherein the at least one ethylenically unsaturated carboxylic acid comprises at least one carbon-carbon double bond that is furnished by one or more functional groups selected from acryloyl, methacryloyl, maleyl, allyl, propenyl, and vinyl. Aspect 4: The method of Aspect 2 or 3, wherein the at least one ethylenically unsaturated carboxylic acid comprises a (meth)acrylate-functionalized carboxylic acid.

[0204] Aspect 5: The method of any of Aspects 2 to 4, wherein the at least one ethylenically unsaturated carboxylic acid comprises a half ester reaction product of a hydroxy-functionalized ethylenically unsaturated compound and a poly carboxylic acid or carboxylic acid anhydride.

[0205] Aspect 6: The method of Aspect 5, wherein at least one carboxylic acid group of the half ester reaction product is esterified with one or more glycidyl-functional compounds, preferably a glycidyl ether or ester, more preferably an alkyl or aryl glycidyl ether or ester.

[0206] Aspect 7: The method of any of Aspects 1 to 6, wherein the complex corresponds to Formula (I):

[0207] Zn(OC(=O)CR1=CH2)x(O-C(=O)-R2-C(=O)-O-R3O-C(=O)CR4=CH2)y(I) wherein x and y are independently 0, 1, or 2, x + y = 2, R1and R4are the same or different and are H or CH3, and R2and R3are the same or different and are divalent organic moieties each containing two or more carbon atoms.

[0208] Aspect 8: The method of any of Aspects 1 to 7, wherein the polymerizing monomer comprises an ethylenically unsaturated compound

[0209] Aspect 9: The method of any of Aspects 1 to 8, wherein the polymerizing monomer comprises at least one (meth)acrylate-functionalized monomer.

[0210] Aspect 10: The method of any of Aspects 1 to 9, wherein the polymerizing monomer comprises (meth)acrylate esters of aliphatic mono-alcohols, (meth)acrylate esters of alkoxylated aliphatic mono-alcohols, (meth)acrylate esters of aliphatic polyols, (meth)acrylate esters of alkoxylated aliphatic polyols, (meth)acrylate esters of aromatic ring-containing alcohols, or (meth)acrylate esters of alkoxylated aromatic ring-containing alcohols.

[0211] Aspect 11 : The method of any of Aspects 1 to 10, wherein the polymerizing monomer comprises at least one monomer selected from the group consisting of hydroxyethyl methacrylate, hydroxypropyl methacrylate, isobornyl methacrylate, polyethylene glycol dimethacrylates and trimethylolpropane trimethacrylate. Aspect 12: The method of any of Aspects 1 to 11, wherein the polymerizing oligomer is a (meth)acrylate-functionalized oligomer.

[0212] Aspect 13: The method of any of Aspects 1 to 12, wherein the polymerizing oligomer is selected from acidic acrylic (meth)acrylates, epoxy (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates (including amine- and sulfide-modified derivatives thereof), and combinations thereof.

[0213] Aspect 14: The method of any of Aspects 1 to 13, wherein the polymerizing oligomer is one or more urethane (meth)acrylates.

[0214] Aspect 15: The method of any of Aspects 1 to 15, wherein the polymerizing oligomer is one or more urethanes based on aliphatic and / or aromatic polyester polyols, polyether polyols and polycarbonate polyols and aliphatic and / or aromatic polyester diisocyanates and polyether diisocyanates capped with (meth)acrylate end-groups.

[0215] Aspect 16: The method of any of Aspects 1 to 15, wherein the at least one initiator is present in a total amount of from 0.05% to 10% by weight, based on the total weight of the curable composition.

[0216] Aspect 17: The method of any of Aspects 1 to 16, wherein the at least one initiator is present in a total amount of from 0.05 to 5% by weight, based on the total weight of the curable composition.

[0217] Aspect 18: The method of any of Aspects 1 to 17, wherein the at least one initiator is present in a total amount of from 0.1% to 2% by weight, based on the total weight of the curable composition.

[0218] Aspect 19: The method of any of Aspects 1 to 18, wherein the at least one initiator is present in a total amount of from 1% to 2% by weight, based on the total weight of the curable composition.

[0219] Aspect 20: The method of any of Aspects 1 to 19, wherein the curable composition comprises a film or a coating composition.

[0220] Aspect 21 : The method of any of Aspects 1 to 19, wherein the curable composition comprises a primer or an ink composition.

[0221] Aspect 22: The method of any of Aspects 1 to 19, wherein the curable composition comprises an inkjet formulation. Aspect 23: The method of any of Aspects 1 to 21, wherein the curable composition has a viscosity of from 100 to 5,000,000 cps at 25°C.

[0222] Aspect 24: The method of any of Aspects 1 to 19 and 22, wherein the curable composition has a maximum viscosity of at most 15 cps at 45°C.

[0223] Aspect 25: The method of any of Aspects 1 to 19, 22, and 24, wherein the curable composition has a maximum viscosity of at most 10 cps at 45°C.

[0224] Aspect 26: The method of any of Aspects 1 to 19, 22, 24, and 25, wherein the curable composition has a maximum viscosity of at most 5 cps at 45°C.

[0225] Aspect 27 : The method of any of Aspects 1 to 20, wherein the cured composition comprises a cured film or coating.

[0226] Aspect 28: The method of any of Aspects 1 to 19 and 21, wherein the cured composition comprises a cured primer or ink.

[0227] Aspect 29: The method of any of Aspects 1 to 19, 22, and 24-26, wherein the cured composition comprises a cured inkjet formulation.

[0228] Aspect 30: The method of any of Aspects 1 to 29, wherein the liquid zinc (meth)acrylate complex has a number average molecular weight of from 500 to 50,000.

[0229] Aspect 31 : The method of any of Aspects 1 to 30, wherein the liquid zinc (meth)acrylate complex has a number average molecular weight of from 800 to 15,000.

[0230] Aspect 32: The method of any of Aspects 1 to 31, wherein the liquid zinc (meth)acrylate complex has a number average molecular weight of from 1,000 to 10,000.

[0231] Aspect 33: The method of any of Aspects 1 to 32, wherein the substrate comprises paper, fabric, metal, glass, plastic (e.g., thermoplastics such as polyolefins, polycarbonate, acrylonitrile butadiene styrene (ABS), and blends thereof), composites, wood, carbon, fiberglass, nonwovens, ceramics, concrete, and composites thereof.

[0232] Aspect 34: The method of any of Aspects 1 to 33, wherein the substrate comprises polyethylene terephthalate.

[0233] Aspect 35: The method of any of Aspects 1 to 34, wherein the pH of the recycling solution is greater than or equal to 7. Aspect 36: The method of any of Aspects 1 to 35, wherein the pH of the recycling solution is greater than 7 and less than 13.

[0234] Aspect 37: The method of any of Aspects 1 to 36, wherein the pH of the recycling solution is greater than 7 and less than 12.

[0235] Aspect 38: The method of any of Aspects 1 to 37, wherein the pH of the recycling solution is greater than 7 and less than 11.

[0236] Aspect 39: The method of any of Aspects 1 to 38, wherein the pH of the recycling solution is greater than 7 and less than 10

[0237] Aspect 40: The method of any of Aspects 1 to 39, wherein the pH of the recycling solution is greater than 7 and less than 9.

[0238] Aspect 41 : The method of any of Aspects 1 to 34, wherein when the pH of the recycling solution corresponds to a 2% NaOH solution and delamination occurs within 10 minutes of exposure at a solution temperature of 25°C to 85°C.

[0239] Aspect 42: The method of any of Aspects 1 to 41, wherein the recycling solution is an aqueous solution of a base, preferably an inorganic base comprising at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, or combination thereof.

[0240] Aspect 43 : The method of Aspect 42, wherein the base is an organic base that is an amine.

[0241] Aspect 44: The method of any of claims 1 to 43, wherein delamination occurs within 10 minutes of exposure to the recycling solution.

[0242] Aspect 45: The method of any of claims 1 to 44, further comprising retrieving from the recycling solution the substrate substantially free from the cured primer, coating, or ink composition.

[0243] Aspect 46: The method of any of Aspects 1 to 45, wherein the polymerizing oligomer comprises at least one optionally (meth)acrylate-functionalized acidic acrylic oligomer, and wherein at least one acid group of the optionally (meth)acrylate- functionalized acidic acrylic oligomer is esterified with an unsaturated epoxy compound.

[0244] Aspect 47: The method of any of Aspect 46, wherein at least one acid group of the optionally (meth)acrylate-functionalized acidic acrylic oligomer is esterified with a reaction product of acrylic or methacrylic acid or mixtures thereof with glycidyl ethers or esters.

[0245] Aspect 48: The method of Aspects 46 or 47, wherein at least one acid group of the optionally (meth)acrylate-functionalized acidic acrylic oligomer is esterified with a compound selected from the group consisting of glycidyl methacrylate, an acrylate of phenyl glycidyl ether, a methacrylate of phenyl glycidyl ether, and any combination thereof.

[0246] Aspect 49: The method of any of Aspects 1 to 48, wherein the at least one polymerizable monomer comprises at least one polymerizing functional group selected from the group consisting of acrylate (including cyanoacrylate), methacrylate, acrylamide, methacrylamide, styrene, maleate, fumarate, itaconate, allyl, propenyl, vinyl and combinations thereof.

[0247] Aspect 50: The method of any of Aspects 1 to 49, wherein the at least one polymerizable monomer comprises at least one polymerizing functional group selected from the group consisting of acrylate, methacrylate, allyl, vinyl, and combinations thereof.

[0248] Aspect 51 : The method of any of Aspects 1 to 50, wherein the at least one polymerizable monomer is selected from the group consisting of mono-(meth)acrylate esters of aliphatic alcohols (wherein the aliphatic alcohol may be straight chain, branched or alicyclic and may be a mono-alcohol, a di-alcohol or a polyalcohol, provided only one hydroxyl group is esterified with (meth)acrylic acid); mono-(meth)acrylate esters of aromatic alcohols (such as phenols, including alkylated phenols); mono-(meth)acrylate esters of alkylaryl alcohols (such as benzyl alcohol); mono-(meth)acrylate esters of oligomeric and polymeric glycols such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, and polypropylene glycol); mono- (meth)acrylate esters of monoalkyl ethers of glycols and oligoglycols; mono- (meth)acrylate esters of alkoxylated (e.g., ethoxylated and / or propoxylated) aliphatic alcohols (wherein the aliphatic alcohol may be straight chain, branched or alicyclic and may be a mono-alcohol, a di-alcohol or a polyalcohol, provided only one hydroxyl group of the alkoxylated aliphatic alcohol is esterified with (meth)acrylic acid); mono- (meth)acrylate esters of alkoxylated (e.g., ethoxylated and / or propoxylated) aromatic alcohols (such as alkoxylated phenols); and caprolactone mono(meth)acrylates Aspect 52: The method of any of Aspects 1 to 51, wherein the at least one polymerizable monomer is selected from the group consisting of 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-ethoxy ethyl (meth)acrylate; 2- and 3-ethoxypropyl (meth)acrylate; tetrahydrofurfuryl (meth)acrylate; alkoxylated tetrahydrofurfuryl (meth)acrylate; 2-(2- ethoxyethoxy)ethyl (meth)acrylate; cyclohexyl (meth)acrylate; glycidyl (meth)acrylate; isodecyl (meth)acrylate; lauryl (meth)acrylate; 2-phenoxyethyl (meth)acrylate; alkoxylated phenol (meth)acrylates; alkoxylated nonylphenol (meth)acrylates; cyclic trimethylolpropane formal (meth)acrylate; isobornyl (meth)acrylate; tricyclodecanemethanol (meth)acrylate; tert-butylcyclohexanol (meth)acrylate; trimethylcyclohexanol (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)acrylates; hydroxyl ethyl-butyl curable 3-(2-hydroxyalkyl)oxazolidinone (meth)acrylates; and combinations thereof.

[0249] Aspect 53: The method of any of Aspects 1 to 52, wherein the polymerizing monomer comprises an ethylenically unsaturated compound.

[0250] Aspect 54: The method of any of Aspects 1 to 53, wherein the polymerizing monomer comprises at least one (meth)acrylate-functionalized monomer.

[0251] Aspect 55: The method of any of Aspects 1 to 54, wherein the polymerizing monomer comprises at least one monomer selected from the group consisting of (meth)acrylate esters of aliphatic mono-alcohols, (meth)acrylate esters of alkoxylated aliphatic mono-alcohols, (meth)acrylate esters of aliphatic polyols, (meth)acrylate esters of alkoxylated aliphatic polyols, (meth)acrylate esters of aromatic ring-containing alcohols, or (meth)acrylate esters of alkoxylated aromatic ring-containing alcohols.

[0252] Aspect 56: The method of any of Aspects 1 to 55, wherein the polymerizing monomer comprises at least one monomer selected from the group consisting of hydroxyethyl methacrylate, hydroxypropyl methacrylate, isobornyl methacrylate, polyethylene glycol dimethacrylates and trimethylolpropane trimethacrylate. Aspect 57: The method of any of Aspects 1 to 56, wherein the polymerizing oligomer is a selected from urethanes based on aliphatic and / or aromatic polyester polyols, polyether polyols and polycarbonate polyols and aliphatic and / or aromatic polyester diisocyanates and polyether diisocyanates capped with (meth)acrylate end-groups.

[0253] Aspect 58. The method of any of Aspects 1 to 57, wherein the zinc (meth)acrylate complexes has an acid value of at least 10 mg KOH / g copolymer, preferably at least 11 mg KOH / g complex, more preferably at least 12 mg KOH / g complex, more preferably at least 13 mg KOH / g complex, and most preferably at least 13.5 mg KOH / g complex.

[0254] Aspect 59. The method of any of Aspects 1 to 58, wherein the zinc (meth)acrylate complexes has an acid value of 25 mg KOH / g complex, preferably at least 50 mg KOH / g complex, more preferably at least 75 mg KOH / g complex, more preferably at least 90 mg KOH / g complex.

[0255] Examples

[0256] Materials

[0257] NTX5000 : liquid zinc (meth)acrylate complex synthesized as described in Example 2 of US6399672 by substituting 4-methylhexahydrophthalic anhydride for phthalic anhydride and omitting the acetone precipitation step.

[0258] PL460 : mixture of photoinitiators available from Esstech

[0259] SR285: tetrahydrofurfuryl acrylate available from Arkema SR339: 2 -phenoxy ethyl acrylate available from Arkema TPO : 2,4,6-trimethylbenzoyldiphenylphosphine oxide

[0260] Neat oligomer property testing

[0261] Initial experiment consisted of curing NTX5000 96 wt% and 4 wt% PL460 under Hg-UV lamp two passes at 50 ft / min to have a hard brittle film. Parts of this film were taken and placed in a 2 wt% aqueous solution of NaOH. Within a few minutes the film starts cracking and shattering as the Zinc ions are removed from the core and unzipping the crosslinked film to smaller molecular weight strands.

[0262] Clear Inkjet ink formulation and deinking NTX5000 is very polar and high polarity monomers are needed to be miscible with it. It has an acid value of about 100 mg KOH / g complex. NTX5000 was blended with SR285 or SR339 monomers at 10 wt%, 20 wt% and 30 wt % of NTX5000 based on the total weight of the NTX5000 and monomer. Coatings were cured on PET with 4 wt% PL460 based on the total weight of the composition.

[0263] Formulations 1-1 to 1-6 cured well onto PET substrate. Formulations 1-1, 1-2 and 1-4 can be totally delaminated in a 2 wt% aqueous solution of NaOH. Figure 1 shows the substrate before and after contact with the recycling solution for Formulations 1-3 and 1-4 .

[0264] Pigmented Inkjet ink formulation and deinking

[0265] NTX5000 was formulated with pigments to make inkjet inks with carbon black as shown in the formulation below.

[0266] Carbon Black Dispersion

[0267] 40 wt% Mogul E (carbon black (Cabot))

[0268] 56 wt % PRO14796 (methacrylate functionalized acidic acrylic oligomer)

[0269] 4 wt % Solsperse 74000 (polymeric dispersant from Lubrizol)

[0270] Ink Formulation

[0271] 15 wt % Carbon Black Dispersion

[0272] 15 wt % NTX5000

[0273] 10 wt % TPO

[0274] 60 wt % SR285

[0275] Viscosity (45°C): 12.29 cP

[0276] This formulation has shown great promise since the final viscosity is in the right range to be jetted from the inkjet printing plates. The cured inks on PET as shown in Fig. 2 show the deinking of the zinc containing formulation while the control shows adhesion (better controls were shown to have full coverage area not deinking).

[0277] The same formulation was tested to deink in pure water. The printed PET plastic substrate with the above formulation was placed in 80°C deionized water and stirred for 10 min. After this exposure the sample did not laminate or peel from the substrate. This negative control experiments shows that the caustic solution is needed for the deinking process and shows that under humid condition and increased temperatures the inks do not delaminate from the finished printed items.

[0278] Within this specification, embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without departing from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein.

[0279] In some embodiments, the invention herein can be construed as excluding any element or process step that does not materially affect the basic and novel characteristics of the compositions and methods described herein. Additionally, in some embodiments, the invention can be construed as excluding any element or process step not specified herein.

[0280] Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.

Claims

Claims1. A method for recycling a substrate coated with a cured primer, coating, or ink composition, wherein the cured composition is obtained by curing a curable primer, ink, or coating composition comprising: at least one liquid zinc (meth)acrylate complex, the complex comprising a ligand coordinated with zinc; at least one polymerizing monomer and / or oligomer; and at least one initiator, the method comprising the steps of: contacting the substrate coated with the cured primer, coating, or ink composition with a recycling solution having a pH sufficient to delaminate the cured primer, coating, or ink composition from the substrate.

2. The method of claim 1, wherein the ligand comprises at least one ethylenically unsaturated carboxylic acid.

3. The method of claim 1, wherein the at least one ethylenically unsaturated carboxylic acid comprises at least one carbon-carbon double bond that is furnished by one or more functional groups selected from acryloyl, methacryloyl, maleyl, allyl, propenyl, and vinyl.

4. The method of claim 2 or 3, wherein the at least one ethylenically unsaturated carboxylic acid comprises a (meth)acrylate-functionalized carboxylic acid.

5. The method of any of claims 2 to 4, wherein the at least one ethylenically unsaturated carboxylic acid comprises a half ester reaction product of a hydroxyfunctionalized ethylenically unsaturated compound and a polycarboxylic acid or carboxylic acid anhydride.

6. The method of claim 5, wherein at least one carboxylic acid group of the half ester reaction product is esterified with one or more gly ci dyl -functional compounds, preferably a glycidyl ether or ester, more preferably an alkyl or aryl glycidyl ether or ester.

7. The method of any of claims 1 to 6, wherein the complex corresponds to Formula (I):Zn(OC(=O)CR1=CH2)x(O-C(=O)-R2-C(=O)-O-R3O-C(=O)CR4=CH2)y(I) wherein x and y are independently 0, 1, or 2, x + y = 2, R1and R4are the same or different and are H or CH3, and R2and R3are the same or different and are divalent organic moieties each containing two or more carbon atoms.

8. The method of any of claims 1 to 7, wherein the polymerizing monomer comprises an ethylenically unsaturated compound, preferably at least one (meth)acrylate- functionalized monomer, more preferably (meth)acrylate esters of aliphatic mono-alcohols, (meth)acrylate esters of alkoxylated aliphatic mono-alcohols, (meth)acrylate esters of aliphatic polyols, (meth)acrylate esters of alkoxylated aliphatic polyols, (meth)acrylate esters of aromatic ring-containing alcohols, (meth)acrylate esters of alkoxylated aromatic ring-containing alcohols, most preferably at least one monomer selected from the group consisting of hydroxy ethyl methacrylate, hydroxypropyl methacrylate, isobornyl methacrylate, polyethylene glycol dimethacrylates and trimethylolpropane trimethacrylate.

9. The method of any of claims 1 to 8, wherein the polymerizing oligomer is a (meth)acrylate-functionalized oligomer, preferably selected from acidic acrylic (meth)acrylates, epoxy (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates (including amine- and sulfide-modified derivatives thereof), and combinations thereof, more preferably urethane (meth)acrylates, most preferably urethanes based on aliphatic and / or aromatic polyester polyols, polyether polyols and polycarbonate polyols and aliphatic and / or aromatic polyester diisocyanates and polyether diisocyanates capped with (meth)acrylate end-groups.

10. The method of any of claims 1 to 9, wherein the at least one initiator is present in a total amount of from 0.05% to 10%, preferably 0.05 to 5%, more preferably 0.1% to 2%, and most preferably 1% to 2% by weight, based on the total weight of the curable composition.

11. The method of any of claims 1 to 10, wherein the pH of the recycling solution is greater than or equal to 7, such as greater than 7 and less than 13, such as greater than 7 and less than 12, such as greater than 7 and less than 11, such as greater than 7 and less than 10, such as greater than 7 and less than 9.

12. The method of any of claims 1 to 11, wherein the zinc (meth)acrylate complex has an acid value of at least 10 mg KOH / g copolymer, preferably at least 11 mg KOH / gcomplex, more preferably at least 12 mg KOH / g complex, more preferably at least 13 mg KOH / g complex, more preferably at least 13.5 mg KOH / g complex, more preferably 25 mg KOH / g complex, more preferably at least 50 mg KOH / g complex, more preferably at least 75 mg KOH / g complex, and most preferably at least 90 mg KOH / g complex.

13. The method of any of claims 1 to 12, wherein the recycling solution comprises a base, preferably an inorganic base comprising at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, or combination thereof.

14. The method of any of claims 1 to 13, wherein the base is an organic base that is an amine.

15. The method of any of claims 1 to 14, further comprising retrieving from the recycling solution the substrate substantially free from the cured primer, coating, or ink composition.

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