Curable ink compositions with water-sequestration agents

Abstract

Curable ink compositions include a (meth)acrylate-based component and a water sequestration component. The ink composition is inkjet printable. The (meth)acrylate- based component includes an aliphatic (meth)acrylate, aromatic (meth)acrylate, or a combination, a multifunctional (meth)acrylate, and a photoinitiator. The water sequestration component is a reactive pair, the reactive pair being a co-curable epoxy- functional part and a co-curable anhydride-functional part. Upon curing, the ink forms a matrix with epoxy-functional and anhydride-functional groups. The ink composition when disposed and cured is optically clear and has an irreversible water uptake of at least 2% by weight upon exposure to 85°C / 85% Relative Humidity for 7 days.

Description

[0001] CURABLE INK COMPOSITIONS WITH WATER-SEQUESTRATION AGENTS

[0002] Summary

[0003] Disclosed herein are curable ink compositions with water sequestration agents. When cured to form an organic layer, and the water sequestration agents are polymerized into the matrix of the organic layer. Also disclosed are articles formed by disposing the curable ink compositions on a substrate and curing the ink to form an organic layer.

[0004] In some embodiments, the curable ink composition comprises a (meth)acrylate- based component capable of curing to form a (meth)acrylate-based matrix, and a water sequestration component. The ink composition is inkjet printable, having a viscosity of 30 centipoise or less at a temperature of from room temperature to 35°C, and is free from solvents. The (meth)acrylate -based component comprises at least one aliphatic (meth)acrylate, at least one aromatic (meth)acrylate, or a combination thereof, at least one multifunctional (meth)acrylate, and a photoinitiator. The water sequestration component being a reactive pair, the reactive pair being a co-curable epoxy-functional part and a co- curable anhydride-functional part, wherein the co-curable anhydride-functional part comprises a co-curable aromatic anhydride, a co-curable aliphatic anhydride, or a combination thereof.

[0005] Upon curing, the ink composition forms a (meth)acrylate matrix where the (meth)acrylate matrix comprises epoxy-functional group and anhydride-functional groups, such that the (meth)acrylate matrix is capable of water sequestration whereby an anhydride-functional group, upon reacting with water forms acid-functional groups that react with epoxy-functional groups creating irreversible water uptake of the (meth)acrylate-based matrix. The ink composition when disposed and cured is optically clear and has an irreversible water uptake of at least 2% by weight upon exposure to 85°C / 85% Relative Humidity for 7 days.

[0006] Also disclosed are articles formed with the curable ink compositions described above. In some embodiments, the articles comprise a substrate with a first major surface and a second major surface, and a cured organic layer adjacent to at least a portion of the second major surface of the substrate, where the cured organic layer comprises a crosslinked (meth)acrylate-based matrix containing epoxy-functional groups and anhydride-functional groups, and is optically clear, and is formed by curing the curable ink compositions described above.

[0007] Brief Description of the Drawings

[0008] The present application may be more completely understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying drawings.

[0009] Figure 1 is a cross-sectional view of an article of this disclosure.

[0010] Detailed Description

[0011] Optical devices are becoming more and more complex, which impacts what materials can be used in them. In particular, organic polymeric materials have found widespread use in optical devices, however, they still must meet the stringent requirements and demands needed for performance.

[0012] For example, thin organic polymeric fdms are desirable for a wide range of uses in optical devices, as adhesives, protective layers, spacer layers, and the like. As articles have become more complex, the physical demands upon these layers have increased. For example, as optical devices have become more compact, they often include additional layers, resulting in a growing need for thinner layers. At the same time, since the layers are thinner, the layers also need to be more precise. For example, a thin spacer layer (of 1 micrometer thickness) needs to be level and free of gaps and holes in order to provide the proper spacing function. This requires deposition of the organic layer in a precise and consistent manner.

[0013] Additionally, not only do these layers have to fulfill their physical role (adhesion, protection, spacing, and the like) they must also provide the requisite optical properties. Among the properties that are becoming increasingly important is refractive index. As light travels through the layers of a multilayer article, it encounters the interface between layers. If the refractive indices of the layers are different, light can be refracted. Therefore, to minimize this refraction, matching of the refractive indices of layers within a multilayer article is desirable.

[0014] An example of an optical device that utilizes thin film layers are OLED (organic light-emitting diode) devices. In particular, the organic light-emitting devices are susceptible to degradation from the permeation of certain liquids and gases, such as water vapor and oxygen. To reduce permeability to these liquids and gases, barrier coatings are applied to the OLED device, which is known in the art as thin fdm encapsulation. Typically, these barrier coatings require a high refractive index to match with other layers in the devices.

[0015] Typically, the organic thin fdm layers are a cured organic matrix. Because the layers are very thin the barrier layers may have difficulty preventing the transport of water through the barrier layer, especially for example in humid environments. Water can be detrimental to devices such as OLEDs, so it is desirable that the barrier layer have an enhanced ability to prevent water migration. One method is for the organic matrix to absorb the water. Various techniques can be used to make organic thin film layers water absorptive to prevent the passage of water through the organic thin film layer. However, many of these techniques can alter the desirable and necessary properties of the organic thin film layer, such as the optical properties. Also, many of the materials typically used to absorb the water in organic matrices (often referred to as water scavengers) can themselves release small molecules that are detrimental to the organic layer and / or to the device. For example, oxazoladines or alkoxy silanes can be used as water scavengers, but these molecules form ketones and alcohols respectively, and these small molecules are problematic materials to generate within organic thin film layers. Other water scavenging techniques use particulate particles as desiccants to absorb water, such as calcium oxide or nanoclays as described in US Patent Publication No. 2020 / 0181460. However, typically these particles are large enough to scatter light, i.e. the particles are larger than the wavelength of visible light. These particulate particle methods are not suitable for layers that are used in display articles where light needs to pass through the layer requiring that the layer be optically transparent. Therefore, a need remains for methods of water scavenging in organic thin film layers.

[0016] Previously, in US Serial No. 63 / 336363 filed April 29, 2022 titled “Curable High Refractive Index Ink Compositions With Water-Sequestration Agents”, a water scavenging methodology was described that is a water sequestering methodology. This sequestering methodology was a two-step process involving an anhydride / epoxy reactive pair. The process utilizes anhydride -functional groups that react with water to form acid groups, and the acid groups react with epoxy groups. At least one of the anhydride and epoxy was cured into the (meth)acrylate matrix, so the result of this 2-step reaction is the trapping or sequestering of the water within the matrix without the generation of any small molecules.

[0017] This disclosure uses a similar methodology, but in the current water sequestering system, both the epoxy-functional and the anhydride functional parts of the reactive pair are co-curable, and the co-curable anhydride-functional part comprises a co-curable aromatic anhydride, a co-curable aliphatic anhydride, or a combination thereof. Co- curable monomers are advantageous for a variety of reasons. Among the desirable features of the use of co-curable monomers include minimizing outgassing of the cured layers while also maximizing mechanical properties of the cured layers.

[0018] The term “(meth)acrylate” refers to monomeric acrylic or methacrylic esters of alcohols. Acrylate and methacrylate monomers or oligomers are referred to collectively herein as "(meth)acrylates”. Materials referred to as “(meth)acrylate functional” are materials that contain one or more (meth)acrylate groups. The term “(meth)acrylate-based refers to a composition or a layer that contains (meth)acrylates and may contain additional (meth)acrylate co-reactive materials.

[0019] The terms "room temperature" and "ambient temperature" are used interchangeably to mean temperatures in the range of 20°C to 25°C.

[0020] The term “adjacent” as used herein when referring to two layers means that the two layers are in proximity with one another with no intervening open space between them. They may be in direct contact with one another (e.g. laminated together) or there may be intervening layers.

[0021] The terms “polymer” and “macromolecule” are used herein consistent with their common usage in chemistry. Polymers and macromolecules are composed of many repeated subunits. As used herein, the term “macromolecule” is used to describe a group attached to a monomer that has multiple repeating units. The term “polymer” is used to describe the resultant material formed from a polymerization reaction.

[0022] The term “alkyl” refers to a monovalent group that is a radical of an alkane, which is a saturated hydrocarbon. The alkyl can be linear, branched, cyclic, or combinations thereof and typically has 1 to 20 carbon atoms. In some embodiments, the alkyl group contains 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, and ethylhexyl.

[0023] The term “aryl” refers to a monovalent group that is aromatic and carbocyclic. The aryl can have one to five rings that are connected to or fused to the aromatic ring. The other ring structures can be aromatic, non-aromatic, or combinations thereof. Examples of aryl groups include, but are not limited to, phenyl, biphenyl, terphenyl, anthryl, naphthyl, acenaphthyl, anthraquinonyl, phenanthryl, anthracenyl, pyrenyl, perylenyl, and fluorenyl.

[0024] The term “alkylene” refers to a divalent group that is a radical of an alkane. The alkylene can be straight-chained, branched, cyclic, or combinations thereof. The alkylene often has 1 to 20 carbon atoms. In some embodiments, the alkylene contains 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. The radical centers of the alkylene can be on the same carbon atom (i.e., an alkylidene) or on different carbon atoms.

[0025] The term “heteroalkylene” refers to a divalent group that includes at least two alkylene groups connected by a thio, oxy, or -NR- where R is alkyl. The heteroalkylene can be linear, branched, cyclic, substituted with alkyl groups, or combinations thereof. Some heteroalkylenes are poloxyyalkylenes where the heteroatom is oxygen such as for example, -CH2CH2(OCH2CH2)nOCH2CH2-.

[0026] The terms “free radically polymerizable” and “ethylenically unsaturated” are used interchangeably and refer to a reactive group which contains a carbon-carbon double bond which can be polymerized via a free radical polymerization mechanism.

[0027] Unless otherwise indicated, "optically transparent" refers to a layer, film, or article that has a high light transmittance over at least a portion of the visible light spectrum (about 400 to about 700 nm). Typically, optically transparent layers, films, or articles have a luminous transmission of at least 80%.

[0028] Unless otherwise indicated, "optically clear" refers to a layer, film, or article that has a high light transmittance over at least a portion of the visible light spectrum (about 400 to about 700 nm), and that exhibits low haze. Typically, optically clear layers, films, or articles have visible light transmittance values of at least 85%, often at least 90%, and haze values of 5% or less, often 2% or less.

[0029] Disclosed herein are curable compositions that are printable, and thus are described as inks. The curable compositions need not be used as inks, that is to say that they need not be printed and then cured, the curable compositions can be delivered to substrate surfaces in a wide variety of ways, but they are capable of being printed. The terms “curable composition” and “ink” are used interchangeably in this disclosure. In particular, the printable compositions of this disclosure are typically capable of being inkjet printed, which means that they have the proper viscosity and other attributes to be inkjet printed. The term “inkjet printable” is not a process description or limitation, but rather is a material description, meaning that the curable compositions are capable of being inkjet printed, and not that the compositions necessarily have been inkjet printed. This is akin to the expression “hot melt processable”, which means that a composition is capable of being hot melt processed but does not mean that the composition has been hot melt processed.

[0030] The curable ink compositions comprise a (meth)acrylate-based component capable of curing to form a (meth)acrylate -based matrix and a water sequestration component. The (meth)acry late -based component comprises at least one aliphatic (meth)acrylate, at least one aromatic (meth)acrylate, or both; at least one multifunctional (meth)acrylate; and a photoinitiator. The (meth)acrylate-based component, contributes to the formation of a crosslinked matrix.

[0031] The water sequestration component comprises a reactive pair, the reactive pair having epoxy-functional and anhydride-functional parts. The water sequestration component comprises: a co-curable epoxy-functional part and a co-curable anhydride- functional part, where the co-curable anhydride -functional part comprises a co-curable aromatic anhydride, a co-curable aliphatic anhydride, or a combination thereof. As described above, water sequestration by the reactive pair occurs by reaction of water with an anhydride group to form an acid, where the anhydride group is cured into the (meth)acrylate matrix. The acid can then react with an epoxy group to form an additional crosslinking site and secondary hydroxyl groups. Since the epoxy group is also cured into the (meth)acrylate matrix, the water is chemically transformed into chemistry bound into the (meth)acrylate matrix and no small molecule byproducts are generated. This process is called water sequestration because the free water molecules become incorporated into the matrix through a chemical reaction within the cured fdm layer, thus creating irreversible water uptake.

[0032] The ink compositions have a variety of desirable properties including being solvent free and inkjet printable, having a viscosity of 30 centipoise or less at a temperature of from room temperature to 35 °C, and when disposed and cured forms an organic layer that is optically clear. Additionally, the cured organic layer has an irreversible water uptake of at least 2% by weight upon exposure to 85°C / 85% Relative Humidity for 7 days. In some embodiments, the cured ink may have other desirable properties, such as a refractive index of 1.50 or greater.

[0033] The curable ink compositions comprise a (meth)acrylate-based component and a water sequestering component. As mentioned above, the (meth)acrylate -based component comprises: at least one aliphatic (meth)acrylate, at least one aromatic (meth)acrylate, or a combination thereof; at least one multifunctional (meth)acrylate; and a photoinitiator. The choice of these components depends upon the desired properties of the organic layers formed by the curable compositions. In some embodiments, it may be desirable to have a high refractive index, in other embodiments, the refractive index may be less important. In embodiments desiring a high refractive index, typically aromatic monomers are particularly suitable.

[0034] A wide range of aliphatic (meth)acrylates are suitable. If used, in some embodiments, the at least one aliphatic (meth)acrylate comprises a monofunctional (meth)acrylate compound of Formula I:

[0035] H2C=CR2-(CO)-O-R3

[0036] Formula I where R3 is an alkyl group with 2-32 carbon atoms, and R2 is hydrogen or methyl. Examples of suitable aliphatic (meth)acrylates include butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, iso-octyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, behenyl (meth)acrylate, stearyl (meth)acrylate, hexadecyl (meth)acrylate, and heptadecyl (meth)acrylate. A particularly suitable aliphatic (meth)acrylate is lauryl acrylate.

[0037] A wide variety of aromatic (meth)acrylate monomers are suitable for use in the curable ink compositions of this disclosure. Typically, these aromatic (meth)acrylate monomers are monofunctional. A single monofunctional (meth)acrylate monomer may be used or a mixture of monofunctional (meth)acrylate monomers may be used. Generally, the at least one monofunctional (meth)acrylate comprises a compound of Formula II (shown below):

[0038] Formula II wherein at least one R1 comprises an aromatic substituent, t is an integer from 1 to 4, and R2 is hydrogen or methyl.

[0039] A wide variety of aromatic substituents are suitable for the R1 group or groups. Typically, the at least one aromatic substituent R1 comprises a substituted or unsubstituted aromatic group of the type -CFF-Ar, or a heteroatom linked aromatic group of the type -X- Ar, where X is S or O, and each Ar is independently a substituted or unsubstituted phenyl group, a fused aromatic group, or 2 or more alkyl group-linked phenyl or substituted phenyl or substituted phenyl groups.

[0040] Thus, the R1 group or groups may comprise various aromatic substituents such as:

[0041] The aromatic substituent R1 is generally bonded to the aromatic ring of the benzyl group by at least one divalent (e.g. alkylene or ether) linking group. In some embodiments, the aromatic substituent R1 is bonded to the aromatic benzyl ring by two or more divalent (e.g. alkylene or ether) linking groups. Each * denotes the point(s) of attachment to the aromatic ring of Formula II; and Ar is a substituted or unsubstituted phenyl group, a fused aromatic group, or 2 or more alkyl group-linked phenyl or substituted phenyl groups.

[0042] In some favored embodiments, t is 1. Representative structures for Formula II thus include:

[0043]

[0044] In some of the embodiments where t is 1 and the R1 group is *-S-Ar, the compounds can have the general structure of Formula IIA:

[0045] Formula IIA where R2 is H or CH3, X is O, S, or a single bond, Q is O, S, SiR.2 where R is an alkyl group, a carbonyl group (C=O), an amino group NR where R is hydrogen or an alkyl, or an SO2 group, n ranges from 0 to 10 (e.g. n is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10), and L is an alkylene group having 1 to 5 carbon atoms, optionally substituted with hydroxyl groups. Various aromatic alcohols from Sigma-Aldrich are available as starting materials that can be converted to (meth)acrylates by reacting such materials with (meth)acrylic acid or (meth)acrylic acid derivatives. Particularly suitable monofunctional (meth)acrylate monomers include biphenylmethyl acrylate (where R1 is phenyl group) commercially available from Miwon Specialty Chemicals, Columbia, SC as MIRAMER Ml 192 or MIRAMER M1192H.

[0046] The amount of (meth)acrylate monomer employed in the curable ink composition can vary. The “(meth)acrylate monomer”, refers to all the aliphatic and / or aromatic (meth)acrylate monomers present if more than one aliphatic (meth)acrylate, more than one aromatic (meth)acrylate monomer, or a combination of aliphatic and aromatic monomers is used. In some embodiments, the curable ink compositions comprise at least 20% by weight or greater of the (meth)acrylate monomer. In other embodiments, the curable ink composition comprises up to 65% by weight of the (meth)acrylate monomer. As mentioned above, typically the (meth)acrylate monomer is a monofunctional (meth)acrylate.

[0047] As mentioned above, in some embodiments a high refractive index can be a desirable feature. In these embodiments, the (meth)acrylate monomer is typically an aromatic (meth)acrylate monomer with a refractive index greater than 1.50 (e.g. at least 1.51 or 1.52) and may have a refractive index of greater than 1.60. Generally, these aromatic (meth)acrylate monomers are non-halogenated (e.g. non-brominated). In some embodiments, the aromatic (meth)acrylate monomers have a refractive index of at least 1.53, 1.54, 1.55, 1,56, 1,57, 1.58, 1.59, 1.60, or 1.61 and typically no greater than 1.65.

[0048] The curable ink compositions of this disclosure also include at least one multifunctional (meth)acrylate of general Formula III:

[0049] (H2C=CR2-(CO)-O-)nA

[0050] Formula III where R2 is hydrogen or methyl, (CO) is a carbonyl group C=O, A is an n-valent group comprising an alkylene, heteroaromatic, fused aromatic, or a group containing both heteroalkylene and aromatic groups, and n is an integer of 2 or greater. In some embodiments, the multifunctional (meth)acrylate is difunctional (n = 2), in other embodiments, the multifunctional (meth)acrylate is trifunctional (n = 3). Higher functional multifunctional (meth)acrylates are also possible.

[0051] Examples of heteroaromatic groups include thiadiazole groups, thiazole groups, and thiophene groups. Examples of fused aromatic groups include naphthyl groups, anthracenyl groups, and fluorenyl groups. Examples of heteroalkylene groups include polyethylene oxide groups, polypropylene oxide groups, polythioether groups, and the like. Examples of groups containing both heteroalkylene and aromatic groups include ones with the difunctional alkylene groups with 2-10 carbon atoms, and have from 1-10 repeat units, and contain difunctional aromatic groups such as phenylene, benzylene, or linked benzylene groups.

[0052] Examples of a useful multi-functional (meth)acrylates include, but are not limited to, di(meth)acrylates, tri(meth)acrylates, and tetra(meth)acrylates. Useful di(meth)acrylates include, for example, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, alkoxylated 1,6-hexanediol diacrylates, tripropylene glycol diacrylate, dipropylene glycol diacrylate, cyclohexane dimethanol di(meth)acrylate, alkoxylated cyclohexane dimethanol diacrylates, ethoxylated bisphenol A di(meth)acrylates, neopentyl glycol diacrylate, polyethylene glycol di(meth)acrylates, polypropylene glycol di(meth)acrylates, and urethane di(meth)acrylates. Useful tri(meth)acrylates include, for example, trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane triacrylates, ethoxylated trimethylolpropane triacrylates, tris(2-hydroxy ethyl)isocyanurate triacrylate, and pentaerythritol triacrylate.

[0053] In some embodiments, it may be desirable to use multifunctional (meth)acrylate monomers that have functionalities higher than 2. One particularly suitable trifunctional (meth)acrylate is TMPTA (trimethylolpropane triacrylate) that is commercially available under the trade designation “MIRAMER M300” from Miwon Specialty Chemical Co., Ltd. Yongin, Korea.

[0054] Since the multifunctional (meth)acrylate monomers have functionalities of 2 or greater, these monomers serve as crosslinking agents and crosslink the forming polymer. The amount of multifunctional (meth)acrylate monomer is controlled to prevent the polymer from becoming inflexible. Typically, the curable ink composition comprises less than 65% by weight of the multifunctional (meth)acrylate monomer or monomers, and at least 10% by weight of the multifunctional (meth)acrylate monomer or monomers. In some embodiments, the multifunctional (meth)acrylate monomer or monomers are present in an amount of from 15-35% by weight. The (meth)acrylate component also comprises at least one photoinitiator, meaning that the initiator is activated by light, generally ultraviolet (UV) light, although other light sources could be used with the appropriate choice of initiator, such as visible light initiators, infrared light initiators, and the like. Typically, UV photoinitiators are used. Photoinitiators are well understood by one of skill in the art of (meth)acrylate polymerization. Examples of suitable free radical photoinitiators include IRGACURE 4265, IRGACURE 184, IRGACURE 651, IRGACURE 1173, IRGACURE 819, IRGACURE TPO, IRGACURE TPO-L, commercially available from BASF, Charlotte, NC.

[0055] Generally, the photoinitiator is used in amounts of 0.01 to 10 parts by weight, more typically 0.1 to 2.0, parts by weight relative to 100 parts by weight of total reactive components.

[0056] The curable ink compositions also comprise a water sequestration component. As described above, the water sequestration component is an anhydride / epoxy reactive pair. The components of the reactive pair are co-curable with the (meth)acrylate component described above. By this it is meant that each of the anhydride / epoxy reactive pair is a compound with an ethylenically unsaturated group such that it co-cures with the (meth)acrylate components and becomes part of the (meth)acrylate matrix.

[0057] The reaction pair of the water sequestration component comprises at least one epoxy-functional moiety. The epoxy-functional moiety is a co-curable moiety. Epoxy- fimctional (meth)acrylates are particularly suitable co-curable epoxy moieties. Suitable epoxy (meth)acrylates include those described by Formula IV :

[0058] H2C=CR2-(CO)-O-CH2-B

[0059] Formula IV where R2 is hydrogen or methyl; (CO) is a carbonyl group C=O; and B is divalent group comprising an epoxy-functional alkylene or heteroalkylene group. Examples of suitable epoxy (meth)acrylates include the commercially available 3,4-epoxycyclohexylmethyl methacrylate TTA-15 from Jiangsu Tetra New Material Technology. Oxetanes are also suitable monomers, such as those from Tronly (Jiangsu, China). Examples of suitable oxetane-functional monomer is 3-Ethyl-3-methacryloxymethyloxetane. The reaction pair of the water sequestration component also comprises at least one anhydride-functional moiety. The at least one anhydride-functional compound is a co- curable anhydride.

[0060] In some embodiments, the anhydride is a co-polymerizable anhydride comprising an aromatic (meth)acrylate-functional anhydride of Formula V:

[0061] H2C=CR2-(CO)-O-L1-O-(CO)-PA

[0062] Formula V where R2 is hydrogen or methyl; (CO) is a carbonyl group C=O; L1is a divalent linking group comprising an alkylene group with at least 3 carbon atoms; and PA is a substituted or unsubstituted phthalic anhydride group. Phthalic anhydride has the general structure:

[0063] Phthalic anhydride Structure

[0064] In some embodiments, the aromatic anhydride (meth)acrylate comprises an aromatic anhydride (meth)acrylate of Formula V :

[0065] H2C=CR2-(CO)-O-L1-O-(CO)-PA

[0066] Formula V where R2 is hydrogen; (CO) is a carbonyl group C=O; L1is a divalent linking group comprising a branched alkylene group with 3 carbon atoms, or a linear alkylene group with 4 carbon atoms; and PA is an unsubstituted phthalic anhydride group.

[0067] Examples of particularly suitable aromatic anhydride (meth)acrylates include the compounds APTA and ABDA shown below:

[0068]

[0069] ABTA

[0070] In other embodiments, at least a portion of the co-curable anhydride-functional part of the reactive pair of the water sequestration component comprises an aliphatic anhydride (meth)acrylate of Formula VI:

[0071] H2C=CR2-(CO)-O-L2-(CO)-O-(CO)-L2-O-(CO)-CR2=CH2

[0072] Formula VI where R2 is hydrogen or methyl; (CO) is a carbonyl group C=O; each L2is a divalent linking group comprising alkylene groups or heteroalkylene groups linked with an ester linkage.

[0073] In other embodiments, the aliphatic anhydride (meth)acrylate comprises an aliphatic anhydride (meth)acrylate of Formula VI:

[0074] H2C=CR2-(CO)-O-L2-(CO)-O-(CO)-L2-O-(CO)-CR2=CH2

[0075] Formula VI where R2 is hydrogen or methyl; (CO) is a carbonyl group C=O; each L2is a divalent linking group comprising a 2 alkylene groups with at least 2 carbon atoms, linked with an ester linkage.

[0076] An example of a particularly suitable aliphatic anhydride (meth)acrylate is the compound AHDA shown below: [H2C=CH-(CO)-O-CH2-CH2-O-(CO)-CH2CH2-(CO)]2-O

[0077] AHDA

[0078] The amount of each of the parts of the water sequestration component can vary widely. Typically, the co-curable epoxy-functional part is present in an amount of 0.075 - 45% by weight of the total weight of the curable ink composition, and the co-curable anhydride-functional part is present in an amount of 0.075 - 45% by weight of the total weight of the curable ink composition.

[0079] The curable ink composition may contain additional reactive or unreactive components, but such components are not necessary and should be used with care to ensure that they are not detrimental to the final properties of the formed (methacrylate- based polymer. As mentioned above, the curable ink composition is substantially free or free of solvent. The ink formulations may also contain polymerization inhibitors, light stabilizers (e.g. hindered amines), synergists, antioxidants, catalysts, dispersants, leveling agents, and the like as needed or desired.

[0080] Also disclosed herein are articles. In some embodiments, the articles comprise a substrate with a first major surface and a second major surface, and a cured organic layer adjacent to at least a portion of the second major surface of the substrate. The cured organic layer comprises a crosslinked (meth)acrylate-based layer containing epoxy- fimctional groups and anhydride-functional groups and is optically clear. The water sequestration component has been described above and is a reactive pair, the reactive pair being epoxy-functional and anhydride-functional parts. An anhydride group cured into the (meth)acrylate matrix upon reacting with water forms acid-functional groups that react with epoxy-functional groups cured into the (meth)acrylate matrix. Since the epoxy- fimctional and anhydride-functional groups are cured into the (meth)acrylate matrix, the above-described reaction sequence thereby creates irreversible water uptake of the (meth)acrylate-based matrix. In some embodiments, the irreversible water uptake is at least 2% by weight upon exposure to 85°C / 85% Relative Humidity for 7 days.

[0081] The cured organic layer is formed by curing a curable ink composition that has been disposed and cured on at least a portion of the second major surface of the substrate. The curable ink compositions have been described above and comprise a (meth)acrylate- based component capable of curing to form a (meth)acrylate-based matrix, and a water sequestration component. As mentioned above, the (meth)acrylate-based component comprises at least one aliphatic (meth)acrylate, at least one aromatic (meth)acrylate, or both; at least one multifunctional (meth)acrylate; and a photoinitiator. Each of these components is described in detail above. The water sequestration component comprises a reactive pair, the reactive pair being epoxy-functional and anhydride-functional parts. The water sequestration component comprises an epoxy-functional (meth)acrylate, and an anhydride-functional (meth)acrylate compound. The curable ink composition is inkjet printable having a viscosity of 30 centipoise or less at a temperature of from room temperature to 35°C and is free from solvents.

[0082] The cured organic layer can have a wide range of thicknesses. Typically, the cured organic layer is a thin layer. As mentioned above, the curable ink composition can be disposed on the substrate in a wide variety of techniques including but not limited to printing techniques, where inkjet printing is particularly suitable for forming thin layers. In some embodiments, the cured organic layer has a thickness of from 1-16 micrometers.

[0083] As mentioned above, the cured organic layer is adjacent to the second major surface of the substrate. A wide range of substrates are suitable. In some embodiments, the article comprises an electronic device and the substrate comprises an optical electronic component. Examples of suitable optical electronic component comprises at least one of an organic light emitting diode, a quantum dot light emitting diode, a micro light emitting diode, or a quantum nanorod electronic device. An example of a particularly suitable optical electronic component is an organic light emitting diode (OLED). The cured organic layer may be disposed on the optical electronic component, or there may be one or more intervening layers.

[0084] Also disclosed herein are methods for preparing articles, especially optical articles. These methods comprise, providing a substrate with a first major surface and a second major surface, providing a curable ink composition, disposing the curable ink composition on the second major surface of the substrate to form a curable layer, and curing the curable layer to form a cured organic layer. Typically, the cured organic layer has a thickness of from 1-16 micrometers.

[0085] In many embodiments, the disposing of the curable ink composition on the second major surface of the substrate to form a curable layer comprises printing, especially inkjet printing. As described above, inkjet printing has a variety of desirable features that make it particularly suitable for preparing the curable layer, including the ability to deposit precise patterns on complex substrates and form a uniform coating.

[0086] The curable ink compositions used in this method are the curable ink compositions described above. Since the curable ink compositions include a photoinitiator, curing of the curable layer comprises photo curing. The nature of the photoinitiator determines the curing conditions, i.e. radiation wavelength used, duration of the exposure to radiation, etc.

[0087] An example of an article of this disclosure is shown in Figure 1. Figure 1 shows an OLED device 100. The OLED device has base layer 110, with OLED 120 disposed on this base layer. Inorganic barrier layer (typically aluminum oxide) 130, the cured organic layer of this disclosure 140, and another inorganic barrier layer (typically aluminum oxide) 150.

[0088] Examples

[0089] These examples are merely for illustrative purposes only and are not meant to be limiting on the scope of the appended claims. All parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight, unless noted otherwise. The following abbreviations are used: cm = centimeters; mm = millimeters; nm = nanometers; mb = milliliters; RPM = revolutions per minute; g = grams; mTorr = millitorr; Pa = Pascals; MPa = MegaPascals; min = minutes; s = seconds; seem = standard cubic centimeters per minute; W = Watts; J = Joules; Hz = Hertz; RH = Relative Humidity. The terms “weight %”, “% by weight”, and “wt%” are used interchangeably.

[0090] Table of Abbreviations

[0091]

[0092] Test Methods

[0093] Viscosity Measurement

[0094] A Brookfield DV2T viscometer was used to measure the ink’s viscosity. The measuring cylinder and spindle were first cleaned with acetone and isopropyl alcohol (IP A), then blow dried with N2. About 17 mb of ink formulation was filtered with a 1 um filter and loaded in the cylinder. The shear rate was set to 10 Hz and the temperature was to set to 25°C. Viscosity measurement was repeated multiple times, and an average and standard deviation of all data points was taken, in units of centipoise.

[0095] Glass Transition Temperature (Tg) and Modulus

[0096] Dynamic Mechanical Analysis (DMA) was used to measure ink’s Tg and modulus. Ink formulations were UV cured inside a silicone mold (2 inch (5 cm) by 3 inch (8 cm) mold with 5 mm by 2 inch (5 cm) cut-out in center). A caliper was used to measure and record the width and thickness of the resulting ink sample strip before it was loaded into the TA Instruments Q800 DMA. The sample was ramped from 25°C to 150°C at 2°C / min with a strain of 0. 1%. Tg and modulus were extracted from the peak of the Tan Delta curve in °C and storage modulus at 25°C in MPa, respectively.

[0097] Plasma Enhanced Chemical Vapor Deposition (PECVD) Stability

[0098] Preparation of cured thin film samples for SiOxPECVD stability test follows the same procedure described in the previous section. Cured thin film samples were loaded into the PECVD system chamber, in a circle at a constant radium from the center of the chamber, with film side facing up. The following process parameters were used for all depositions. Tetramethylsilane (TMS) and O2 flow rates were maintained at 100 seem and 500 seem, respectively. Plasma Rf power of 1500 W was used and the deposition pressure was held constant at 100 mTorr (13 Pa). Deposition time was controlled to vary layer thickness. A 4 min deposition was typically conducted, giving a 1 ± 0.1 micrometer thick SiO layer. A Si wafer was included in each run for thickness measurement of SiO layer later by an Ellipsometer. The chamber plate temperature was measured using an infrared thermometer before the deposition. A starting plate temperature of 40°C was used. The transmission and haze of the ink samples were characterized using a Haze-gard (BYK- Gardner haze-gard plus) after PECVD deposition. Ink samples with haze <2% pass the test, while samples with haze >10% fail.

[0099] Water Absorption Tests

[0100] Cured specimens were made according to the description in the section entitled “Glass Transition Temperature (Tg) and Modulus” above. These samples were first baked at 85°C for 2 days to remove residual moisture and convert any unreacted monomers. Each specimen was weighed (A). Then, the specimens were kept in an oven set to 85°C, 85% relative humidity for 7 days. They were immediately weighed again (B). Finally, samples were baked again at 85°C for 2 more days to remove physically adsorbed moisture, and then weighed (C).

[0101] Maximum water uptake% = (B - A) / A x 100 Irreversible water uptake% = (C - A) / A x 100 Physically adsorbed water% = (B - C) / A x 100

[0102] FT-IR measurement

[0103] All cured and liquid samples were measured on Thermo iS50 FT-IR at Attenuated Total Reflectance mode.

[0104] Refractive Index Measurement Approximately 0.2 mL of an example was dropped on a clean glass substrate. A wire-wound rod was used to obtain a fdm of approximately 5 micrometers. The fdm was cured in a nitrogen chamber, as described in Test Method 1 under 395 nm LED light (0.6 W / cm2for 5 sec = 3 J / cm2). The refractive index of the cured fdm at 450 nm wavelength was measured on 2010M Prism Coupler (Metricon, NJ, USA).

[0105] Synthesis Examples

[0106] Preparation of anhydride monomers

[0107] SE-1: Preparation of acryloxybutyltrimellitic anhydride (ABTA)

[0108] A solution of 50.00 g (0.24 mol) of trimellitic anhydride chloride in 200 mL dichloromethane was cooled in an ice bath. A solution of 34.225 g (0.24 mol) of 4- hydroxybutyl acrylate, 20 g of pyridine, and 250 mL dichloromethane was added dropwise to the flask over 1 hour. Stirred overnight at room temperature. After 17 hours, the mixture was washed with 1.0 M HC1 and water. To the solution 0.05 g of phenothiazine was added, and the solution turned dark orange. The organic phase was concentrated to give an oil which crystallized into a solid. A mixture of toluene and hexane was used to recrystallize the product. The recrystallization was repeated four times to get most of the color out of the product. The final product was isolated as a grey / white solid (46.28 g).

[0109] SE-2: Preparation of acryloxypropyltrimellitic anhydride (APTA)

[0110] A solution of 12.36 g (9.5 mmol) of hydroxypropyl acrylate (mixture of isomers), 8.00 g (0.10 mol) of pyridine, and 100 m dichloromethane was cooled in an ice bath. A solution of 20.00 g (9.5 mmol) of trimellitic anhydride chloride in 125 m dichloromethane was added dropwise to the flask over 1 hour. Stirred overnight at room temperature. After 17 hours, the mixture was filtered, then concentrated under vacuum. Ethyl acetate (150 mb) was added and the mixture was washed with 1.0 M HC1 and water. The organic phase was concentrated to give an oil. The crude oil was purified by column chromatography over silica gel using a gradient of 12 to 80% ethyl acetate in heptane. The product was isolated as a thick oil (13.49 g).

[0111] SE-3 : Preparation of acryloxyethyl succinate anhydride (AHDA)

[0112] A mixture of 25.00 g (0.116 mol) of acryloxyethyl succinate mono ester, 47.22 g (0.463 mol) acetic anhydride, and 20 mg 2,6-Di-tert-butyl-4-methylphenol (BHT) was heated to 110°C for 90 minutes. The mixture was cooled, then concentrated under vacuum. The crude liquid was purified by column chromatography over silica gel using a gradient of ethyl acetate in hexane. The product was isolated as a colorless oil (12.90 g).

[0113] Examples E1-E6 and Comparative Examples CE1-CE7

[0114] Preparation of Ink Compositions

[0115] The components shown in Tables 1 and 2 were stirred at 300 rpm for 10 min in amber glass vials bottles. The tables express the relative amounts of each component in terms of parts by weight. Table 1 Table 2

[0116] Curing Procedure

[0117] Unless noted otherwise, ink samples were all cured using a 395 nm UV lamp (Phoseon Technology) at 0.24 W / cm2power for 30 s (equal to 7.2 J / cm2in dose) in a custom-made box filled with N2.

[0118] Properties of Inks and of Cured Lavers After mixing the ink compositions were classified as soluble “good” or not soluble “not soluble”. Compositions that were not soluble were not further tested. The viscosity was measured as described in the test methods above. PECVD testing was carried out and the cured samples are reported as “PASS” or “FAIL”. The Modulus and Tg were measured as described in the test methods above. The Refractive Index (RI) was measured as described in the test methods above. The results are presented in Tables 3 and 4 below.

[0119] Table 3 able 4

[0120] Water Absorption

[0121] Maximum uptake is the weight measured after 7 days at 85°C, 85% RH condition. Irreversible uptake is the weight measured after 2 additional days at 85°C drying. One anhydride captures one water molecule, and there is no change in molecular weight thereafter. Therefore, weight increases in proportion to anhydride amount according to the following equation:

[0122] Theoretical maximum water uptake (%)

[0123] The results are reported in Table 5 below.

[0124] Table 5

[0125] ATR-FTIR Measurements

[0126] ATR-FTIR spectra were obtained for samples El and E5 using the test methods described above. For El, the anhydride C=O stretch is located at 1822 cm"1. After exposure to moisture, the peak is lost and a broadening of the carbonyl stretch (1680 to 1750 cm"1) is observed. This indicates that the anhydride groups were dissociated to carboxylic acid groups. In E5, a similar trend is observed. The ABTA anhydride C=O stretch is located at 1780 cm"1. After exposure to moisture, the peak is lost and a broadening of the carbonyl stretch (1680 to 1750 cm"1) is once again observed. This indicates that the anhydride groups were dissociated to carboxylic acid groups.

Claims

What is claimed is:

1. A curable ink composition comprising: a (meth)acrylate-based component capable of curing to form a (meth)acrylate- based matrix, comprising: at least one aliphatic (meth)acrylate, at least one aromatic (meth)acrylate, or a combination thereof; at least one multifunctional (meth)acrylate; and a photoinitiator; and a water sequestration component, the water sequestration component being a reactive pair, the reactive pair being a co-curable epoxy-functional part and a co-curable anhydride-functional part, wherein the co-curable anhydride -functional part comprises a co-curable aromatic anhydride, a co-curable aliphatic anhydride, or a combination thereof; such that upon curing, the ink composition forms a (meth)acrylate matrix wherein the (meth)acrylate matrix comprises epoxy-functional group and anhydride-functional groups, and wherein the (meth)acrylate matrix is capable of water sequestration whereby an anhydride-functional group, upon reacting with water forms acid-functional groups that react with epoxy-functional groups creating irreversible water uptake of the (meth)acrylate-based matrix, wherein the ink composition is inkjet printable, having a viscosity of 30 centipoise or less at a temperature of from room temperature to 35 °C, and is free from solvents, and wherein the ink composition when disposed and cured is optically clear, and has an irreversible water uptake of at least 2% by weight upon exposure to 85°C / 85% Relative Humidity for 7 days.

2. The curable ink composition of claim 1, wherein the at least one aliphatic (meth)acrylate comprises a monofunctional (meth)acrylate compound of Formula I:H2C=CR2-(CO)-O-R3Formula I wherein R3 is an alkyl group with 2-32 carbon atoms; andR2 is hydrogen or methyl.

3. The curable ink composition of claim 1, wherein the at least one aromatic (meth)acrylate comprises a monofunctional (meth)acrylate compound of Formula I:Formula II wherein at least one R1 comprises an aromatic substituent; t is an integer from 1 to 4; andR2 is hydrogen or methyl.

4. The curable ink composition of claim 1, wherein the at least one multifunctional (meth)acrylate comprises a compound of Formula II:(H2C=CR2-(CO)-O-)nAFormula III wherein R2 is hydrogen or methyl;(CO) is a carbonyl group C=O; andA is an n-valent group comprising an alkylene group, a heteroaromatic group, a fused aromatic group, a heteroalkylene group, or a group containing both heteroalkylene and aromatic groups; and n is an integer of 2 or greater.

5. The curable ink composition of claim 1, wherein at least a portion of the co-curable epoxy-functional part of the reactive pair of the water sequestration component comprises an epoxy-functional (meth)acrylate of Formula IV:H2C=CR2-(CO)-O-CH2-BFormula IV wherein R2 is hydrogen or methyl;(CO) is a carbonyl group C=O; andB is an epoxy-functional alkyl or heteroalkyl group.

6. The curable ink composition of claim 1, wherein at least a portion of the co-curable anhydride-functional part of the reactive pair of the water sequestration component comprises an aromatic anhydride (meth)acrylate of Formula V:H2C=CR2-(CO)-O-L1-O-(CO)-PAFormula V wherein R2 is hydrogen or methyl;(CO) is a carbonyl group C=O;L1is a divalent linking group comprising an alkylene group with at least 3 carbon atoms; andPA is a substituted or unsubstituted phthalic anhydride group.

7. The curable ink composition of claim 6, wherein the aromatic anhydride (meth)acrylate comprises an aromatic anhydride (meth)acrylate of Formula V:H2C=CR2-(CO)-O-L1-O-(CO)-PAFormula V wherein R2 is hydrogen;(CO) is a carbonyl group C=O;L1is a divalent linking group comprising a branched alkylene group with 3 carbon atoms, or a linear alkylene group with 4 carbon atoms; andPA is an unsubstituted phthalic anhydride group.

8. The curable ink composition of claim 1, wherein at least a portion of the co-curable anhydride-functional part of the reactive pair of the water sequestration component comprises an aliphatic anhydride (meth)acrylate of Formula VI:H2C=CR2-(CO)-O-L2-(CO)-O-(CO)-L2-O-(CO)-CR2=CH2Formula VIwherein R2 is hydrogen or methyl;(CO) is a carbonyl group C=O; each L2is a divalent linking group comprising alkylene groups or heteroalkylene groups linked by an ester group.

9. The curable ink composition of claim 8, wherein the aliphatic anhydride (meth)acrylate comprises an aliphatic anhydride (meth)acrylate of Formula VI:H2C=CR2-(CO)-O-L2-(CO)-O-(CO)-L2-O-(CO)-CR2=CH2Formula VI wherein R2 is hydrogen;(CO) is a carbonyl group C=O; each L2is a divalent linking group comprising an alkylene group with at least 2 carbon atoms and an ester group.

10. The curable ink composition of claim 1, wherein the co-curable epoxy-functional part comprises 0.075 - 45% by weight of the total weight of the curable ink composition.

11. The curable ink composition of claim 1, wherein the co-curable anhydride -functional part comprises 0.075 - 45% by weight of the total weight of the curable ink composition.

12. An article comprising: a substrate with a first major surface and a second major surface; a cured organic layer adjacent to at least a portion of the second major surface of the substrate, wherein the cured organic layer comprises a crosslinked (meth)acrylate-based matrix containing epoxy-functional groups and anhydride-functional groups, and is optically clear; such that the cured organic layer has a water sequestration component, the water sequestration component being a reactive pair, the reactive pair being epoxyfunctional and anhydride-functional parts, wherein the (meth)acrylate matrix is capable of water sequestration whereby an anhydride-functional group, upon reacting with water forms acid-functional groups that react with epoxy-functional groups creating irreversiblewater uptake of the (meth)acrylate-based matrix,, wherein the irreversible water uptake is at least 2% by weight upon exposure to 85°C / 85% Relative Humidity for 7 days.

13. The article of claim 12, wherein the cured organic layer comprises a curable ink composition that has been disposed and cured on at least a portion of the second major surface of the substrate, wherein the curable ink composition comprises: a (meth)acrylate-based component capable of curing to form a (meth)acrylate- based matrix, comprising: at least one aliphatic (meth)acrylate, at least one aromatic (meth)acrylate, or a combination thereof; at least one multifunctional (meth)acrylate; and a photoinitiator; and a water sequestration component, the water sequestration component being a reactive pair, the reactive pair being a co-curable epoxy-functional part and a co-curable anhydride-functional part, wherein the co-curable anhydride- functional part comprises a co-curable aromatic anhydride, a co-curable aliphatic anhydride, or a combination thereof; wherein the curable ink composition is inkjet printable having a viscosity of 30 centipoise or less at a temperature of from room temperature to 35 °C and is free from solvents.

14. The article of claim 12, wherein the cured organic layer has a thickness of from 1-16 micrometers.

15. The article of claim 12, wherein the article comprises an electronic device and the substrate comprises an optical electronic component.

16. The article of claim 15, wherein the optical electronic component comprises an organic light emitting diode (OLED), a quantum dot light emitting diode, a micro light emitting diode, or a quantum nanorod electronic device.

17. The article of claim 13, wherein at least a portion of the co-curable epoxy-functional part of the reactive pair of the water sequestration component comprises an epoxy- fimctional (meth)acrylate of Formula IV :H2C=CR2-(CO)-O-CH2-BFormula IV wherein R2 is hydrogen or methyl;(CO) is a carbonyl group C=O; andB is an epoxy-functional alkyl or heteroalkyl group.

18. The article of claim 13, wherein at least a portion of the co-curable anhydride- functional part of the reactive pair of the water sequestration component comprises an aromatic anhydride (meth)acrylate of Formula V :H2C=CR2-(CO)-O-L1-O-(CO)-PAFormula V wherein R2 is hydrogen or methyl;(CO) is a carbonyl group C=O;L1is a divalent linking group comprising a branched alkylene group with 3 carbon atoms, or a linear alkylene group with 4 carbon atoms; and PA is an unsubstituted phthalic anhydride group.

19. The article of claim 13, wherein at least a portion of the co-curable anhydride- functional part of the reactive pair of the water sequestration component comprises an aliphatic anhydride (meth)acrylate of Formula VI:H2C=CR2-(CO)-O-L2-(CO)-O-(CO)-L2-O-(CO)-CR2=CH2Formula VI wherein R2 is hydrogen or methyl;(CO) is a carbonyl group C=O;L2is a divalent linking group comprising a 2 alkylene groups with at least 2 carbon atoms, linked with an ester linkage.

20. The article of claim 13, wherein the co-curable epoxy-functional part comprises 0.075 - 45% by weight of the total weight of the curable ink composition.

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