KR20210147749A - Photocurable Ink Composition, Encapsulation Layer and Display Device - Google Patents

Abstract

Provided are: a photocurable ink composition comprising a specific proportion of a monofunctional photocurable monomer having a specific structure; an encapsulation layer including a cured product thereof; and an image display device comprising the encapsulation layer. The photocurable ink composition according to the present invention has a low dielectric constant by comprising a specific proportion of a monofunctional photocurable monomer having a specific structure, so it does not slow down the signal speed. In addition, the photocurable ink composition of the present invention can implement a low viscosity by using a photocurable monomer as a diluent without having to use a solvent, thereby enabling a fine-patterning process using inkjet printing.

Description

Photocurable Ink Composition, Encapsulation Layer and Display Device {Photocurable Ink Composition, Encapsulation Layer and Display Device}

The present invention relates to a photocurable ink composition, an encapsulation layer, and an image display device, and more particularly, by having a low dielectric constant, the signal speed can not be slowed down, and a low viscosity can be realized, so that fine patterning is possible through inkjet printing. It relates to a chemical conversion ink composition, an encapsulation layer comprising a cured product thereof, and an image display device comprising the encapsulation layer.

In an organic light emitting device (OLED), an organic light emitting layer is formed for each pixel, and an encapsulation layer for protecting the organic light emitting layer from external impurities or moisture may be formed.

An inorganic encapsulation layer including silicon oxide, silicon nitride and/or silicon oxynitride may be formed as the encapsulation layer. However, the inorganic encapsulation layer may not sufficiently block deterioration of the display element due to external moisture. Accordingly, it may be considered to form an additional organic encapsulation layer using the photocurable composition.

Recently, as the resolution of an OLED device increases, patterns and pixel sizes are also being miniaturized. Accordingly, the photocurable composition also needs to have properties suitable for fine application or fine patterning.

Korean Patent No. 10-1359470 includes an alkali-soluble resin, a photocurable monomer, a photopolymerization initiator, a p-dimethylaminoacetophenone-based or aminobenzaldehyde-based hydrogen donor and a solvent, and activates the alkyl radical generated in the photopolymerization initiator A photocurable composition capable of improving reactivity is disclosed.

However, since the photocurable composition includes an alkali-soluble resin and increases in viscosity, there is a limit to the implementation of desired fine patterning.

On the other hand, as represented by the spread of video transmission via optical fiber communication lines and wireless communication lines, the amount of information communication handled is rapidly increasing. Accordingly, a high speed of the image display device is required, and for this high speed, it is necessary to lower the dielectric constant in order to reduce the storage capacity of the encapsulation layer.

Korean Patent Registration No. 10-1826020 includes a photoresponsive gas generator comprising a skeleton containing a hetero atom and a branched chain having at least one nitrogen atom bonded to the skeleton and generating gas by irradiation with light. However, there is disclosed a solvent-free photocurable inkjet composition in which the skeleton containing the hetero atom has a benzocarbazole structure or a phenylthiophenyl structure.

However, since the photocurable inkjet composition does not consider securing of a low dielectric constant, it may be difficult to increase the speed of the image display device.

Therefore, the development of a photocurable ink composition capable of fine patterning through inkjet printing is urgently required because it has a low dielectric constant, so that the signal speed cannot be slowed and a low viscosity can be realized.

Republic of Korea Patent No. 10-1359470 Republic of Korea Patent No. 10-1826020

One object of the present invention is to provide a photocurable ink composition capable of not slowing down a signal speed by having a low dielectric constant, and realizing a low viscosity and capable of fine patterning through inkjet printing.

Another object of the present invention is to provide an encapsulation layer including a cured product of the photocurable ink composition.

Another object of the present invention is to provide an image display device including the encapsulation layer.

On the other hand, the present invention includes a compound of Formula 1 below, a 2- to trifunctional photocurable monomer, and a photopolymerization initiator, wherein the compound of Formula 1 is included in an amount of 10 to 80% by weight based on 100% by weight of the total composition A photocurable ink composition is provided.

[Formula 1]

In the above formula,

R ¹ is hydrogen or a methyl group,

R ² is a C ₅ -C ₃₀ alkyl group or a C ₅ -C ₃₀ cycloalkyl group.

The photocurable ink composition according to an embodiment of the present invention may have a viscosity of 10 to 30 cP at 25° C., and a dielectric constant of a cured film of 3.0 or less.

In one embodiment of the present invention, the 2- to trifunctional photocurable monomer may include at least one of compounds represented by the following Chemical Formulas 2-1 to 2-3.

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

In the above formula,

R ¹ is each independently hydrogen or a methyl group,

R ³ is hydrogen or a C ₁ -C ₃ alkyl group,

R ⁴ is hydrogen, a hydroxyl group, a C ₁ -C ₃ alkyl group or a C ₁ -C ₃ alkoxy group,

L is a C ₂ -C ₂₀ alkylene group,

n is each independently an integer from 0 to 10;

The photocurable ink composition according to an embodiment of the present invention contains 10 to 80% by weight of the compound of Formula 1, 10 to 40% of a difunctional photocurable monomer, and a trifunctional photocurable monomer based on 100% by weight of the total photocurable ink composition 5 to 40% by weight.

The photocurable ink composition according to an embodiment of the present invention may include a solvent in an amount of 1 wt% or less.

The photocurable ink composition according to an embodiment of the present invention may be used for encapsulating an organic light emitting device.

On the other hand, the present invention provides an encapsulation layer including a cured product of the photocurable ink composition.

On the other hand, the present invention provides an image display device including the encapsulation layer.

The photocurable ink composition according to the present invention may include a monofunctional photocurable monomer having a specific structure in a specific content to have a low dielectric constant of 3.0 or less, thereby not slowing down the signal speed. In addition, the photocurable ink composition according to the present invention can implement a low viscosity of 10 to 30 cP at 25° C. using a photocurable monomer as a diluent without a solvent, so that fine patterning is possible through inkjet printing. Accordingly, the photocurable ink composition according to an embodiment of the present invention may be advantageously used for encapsulation of an organic light emitting device.

In addition, the photocurable ink composition according to an embodiment of the present invention may have excellent gas and moisture barrier properties after curing, and may have improved curing degree and stability.

Hereinafter, the present invention will be described in more detail.

One embodiment of the present invention relates to a photocurable ink composition comprising a monofunctional photocurable monomer (A), a 2 to trifunctional photocurable monomer (B), and a photoinitiator (C).

The photocurable ink composition according to an embodiment of the present invention may have a viscosity of 10 to 30 cP at 25°C. If the viscosity at 25°C is less than 10 cP, difficult jetting may occur during jetting, and if it exceeds 30 cP, the jetting property may be poor.

In the photocurable ink composition according to an embodiment of the present invention, the dielectric constant of the cured film may be 3.0 or less, preferably 2.7 or less.

The permittivity is a physical unit indicating the effect of a medium between charges on the electric field when an electric field acts between the charges, and may be viewed as the amount of charge that the medium can store.

The dielectric constant of the cured film of the photocurable ink composition according to an embodiment of the present invention is a value measured at a frequency of 100 kHz according to the method described in Experimental Examples to be described later with respect to a sample on which a cured film having a thickness of 8 μm is formed after curing.

The dielectric constant of the cured film may be 3.0 or less as described above, for example, more than 1 and less than 3.0, preferably more than 1 and less than 2.7. When the dielectric constant of the cured film is greater than 3.0, the signal speed may be slow.

The photocurable ink composition according to an embodiment of the present invention has a low dielectric constant of 3.0 or less to realize a low viscosity of 10 to 30 cP at 25°C by using a photocurable monomer as a diluent without a solvent without slowing down the signal rate. Thus, fine patterning is possible through inkjet printing. Accordingly, the photocurable ink composition according to an embodiment of the present invention may be advantageously used for encapsulation of an organic light emitting device.

Monofunctional photocurable monomer (A)

In one embodiment of the present invention, the monofunctional photocurable monomer (A) is a compound of Formula 1 below, and serves to lower the dielectric constant of the photocurable ink composition, and also advantageously functions to implement low viscosity.

[Formula 1]

In the above formula,

R ¹ is hydrogen or a methyl group,

R ² is a C ₅ -C ₃₀ alkyl group or a C ₅ -C ₃₀ cycloalkyl group.

As used herein, C ₅ -C ₃₀ Alkyl group means a straight-chain or branched hydrocarbon consisting of 5 to 30 carbon atoms, for example, pentyl, hexyl, 2-ethylhexyl, heptyl, 2-ethylheptyl, octyl , nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, stearyl, nonadecyl, eicosanyl, behenyl, and the like.

As used herein, a C ₅ -C ₃₀ cycloalkyl group refers to a simple or fused cyclic hydrocarbon composed of 5 to 30 carbon atoms, and includes, for example, cyclopentyl, cyclohexyl, and the like, but is not limited thereto.

Specifically, the compound of Formula 1 has a low dipole moment value caused by a difference in electronegativity within a molecule, which is advantageous in realizing a low dielectric constant.

In one embodiment of the present invention, R ² is preferably a C ₇ -C ₃₀ alkyl group or a C ₇ -C ₃₀ cycloalkyl group, more preferably a C ₁₀ -C ₂₅ alkyl group or C ₇ -C ₂₅ cyclo It may be an alkyl group. When R ² is a C ₇ -C ₃₀ alkyl group or a C ₇ -C ₃₀ cycloalkyl group, it is preferable in terms of low dielectric constant and low viscosity.

Specific examples of the compound of Formula 1 include dodecyl (meth) acrylate, stearyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isostearyl (meth) acrylate, behenyl (meth) Acrylates etc. are mentioned.

The compound of Formula 1 is included in an amount of 10 to 80% by weight, preferably 20 to 70% by weight, based on 100% by weight of the total photocurable ink composition. If the content of the compound of Formula 1 is less than 10% by weight, the dielectric constant may be increased or the viscosity of the photocurable ink composition may increase to deteriorate jetting properties, and if it exceeds 80% by weight, difficult jetting may occur during jetting.

2-3 functional photocurable monomer (B)

In one embodiment of the present invention, the 2- to trifunctional photocurable monomer (B) is a compound that can be polymerized by the action of light and a photopolymerization initiator to be described later, and is represented by the following Chemical Formulas 2-1 to 2-2. It may include at least one of a functional photo-curable monomer and a trifunctional photo-curable monomer represented by the following Chemical Formula 2-3.

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

In the above formula,

R ¹ is each independently hydrogen or a methyl group,

R ³ is hydrogen or a C ₁ -C ₃ alkyl group,

R ⁴ is hydrogen, a hydroxyl group, a C ₁ -C ₃ alkyl group or a C ₁ -C ₃ alkoxy group,

L is a C ₂ -C ₂₀ alkylene group,

n is each independently an integer from 0 to 10;

As used herein, C ₁ -C ₃ Alkyl group refers to a linear or branched monovalent hydrocarbon composed of 1 to 3 carbon atoms, and includes, for example, methyl, ethyl, n-propyl, i-propyl, etc. The present invention is not limited thereto.

As used herein, the C ₁ -C ₃ alkoxy group refers to a straight-chain or branched alkoxy group having 1 to 3 carbon atoms, and includes, but is not limited to, methoxy, ethoxy, n-propanoxy, and the like.

As used herein, the C ₂ -C ₂₀ alkylene group refers to a straight-chain or branched divalent hydrocarbon having 2 to 20 carbon atoms, for example, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, n-pentylene, n-hexylene, n-heptylene, n-octylene, n-nonylene, 1-methylheptylene, and the like.

The C ₅ -C ₃₀ alkyl group, C ₅ -C ₃₀ cycloalkyl group, C ₁ -C ₃ alkyl group, C ₁ -C ₃ alkoxy group, and C ₂ -C ₂₀ alkylene group are one or more hydrogen groups. C ₁ -C ₆ Alkyl group, C ₂ -C ₆ alkenyl group, C ₂ -C ₆ alkynyl group, C ₃ -C ₁₀ cycloalkyl group, C ₃ -C ₁₀ heterocycloalkyl group, C ₃ -C ₁₀ heterocycloalkyloxy group, C ₁ -C ₆ haloalkyl group, C ₁ -C ₆ alkoxy group, C ₁ -C ₆ thioalkoxy group, aryl group, acyl group, hydroxy, thio (thio), It may be substituted with halogen, amino, alkoxycarbonyl, carboxy, carbamoyl, cyano, nitro and the like.

Specific examples of the compound represented by Formula 2-1 include 1,4-bis((meth)acryloyloxy)butane, 1,6-hexanediol di(meth)acrylate, 2-methyl-1,8 -octanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, etc. are mentioned.

Specific examples of the compound represented by Formula 2-2 include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate and the like.

Specific examples of the compound represented by Formula 2-3 include trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, and pentaerythritol tri(meth)acrylate. can

The photocurable ink composition according to an embodiment of the present invention may include the difunctional photocurable monomer in an amount of 10 to 40 wt% based on 100 wt% of the total photocurable ink composition. If the content of the bifunctional photocurable monomer is less than 10% by weight, pencil hardness may be lowered, and if it exceeds 40% by weight, jetting properties may be poor.

The photocurable ink composition according to an embodiment of the present invention may include the trifunctional photocurable monomer in an amount of 5 to 40 wt% based on 100 wt% of the total photocurable ink composition. If the content of the trifunctional photocurable monomer is less than 5% by weight, pencil hardness may be lowered, and if it exceeds 40% by weight, the viscosity may increase and jetting properties may be poor.

Photoinitiator (C)

In one embodiment of the present invention, the photopolymerization initiator (C) may be used without particularly limiting the type as long as it can polymerize the photocurable monomer. In particular, the photopolymerization initiator (C) is an acetophenone-based compound, a benzophenone-based compound, a triazine-based compound, a biimidazole-based compound, an oxime-based compound and It is preferable to use at least one compound selected from the group consisting of thioxanthone-based compounds.

Specific examples of the acetophenone-based compound include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 2-hydroxy-1-[4-(2-hydroxyl) oxyethoxy)phenyl]-2-methylpropan-1-one, 1-hydroxycyclohexylphenylketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one; 2-Benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propane-1 -one, 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one, etc. are mentioned.

Examples of the benzophenone compound include benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra( tert-butylperoxycarbonyl)benzophenone and 2,4,6-trimethylbenzophenone.

Specific examples of the triazine-based compound include 2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6 -(4-Methoxynaphthyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-piperonyl-1,3,5-triazine, 2,4-bis (trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(5-methylfuran-2- yl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)ethenyl]-1,3,5-triazine , 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl )-6-[2-(3,4-dimethoxyphenyl)ethenyl]-1,3,5-triazine etc. are mentioned.

Specific examples of the biimidazole-based compound include 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole, 2,2'-bis(2,3- Dichlorophenyl)-4,4',5,5'-tetraphenylbiimidazole, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetra(alkoxyphenyl)biimi Dazole, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetra(trialkoxyphenyl)biimidazole, 2,2-bis(2,6-dichlorophenyl)-4 ,4',5,5'-tetraphenyl-1,2'-biimidazole or a biimidazole compound in which the phenyl group at the 4,4',5,5' position is substituted with a carboalkoxy group; have. Among them, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole, 2,2'-bis(2,3-dichlorophenyl)-4,4' ,5,5'-tetraphenylbiimidazole, 2,2-bis(2,6-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole is preferably used

Specific examples of the oxime-based compound include o-ethoxycarbonyl-α-oxyimino-1-phenylpropan-1-one, and commercially available products include Irgacure OXE 01 and OXE 02 manufactured by BASF.

Examples of the thioxanthone-based compound include 2-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, and the like. There is this.

The photopolymerization initiator (C) may be included in an amount of 1 to 10 wt%, preferably 1 to 5 wt%, based on 100 wt% of the total photocurable ink composition. When the photopolymerization initiator is included within the above range, it is preferable because the photocurable ink composition is highly sensitive and the exposure time is shortened, so that productivity can be improved. In addition, there is an advantage in that the strength of the cured film formed by using the photocurable ink composition according to the present invention and smoothness on the surface of the cured film are improved.

Additive (D)

The photocurable ink composition according to an embodiment of the present invention may further include additives such as a surfactant and an adhesion promoter in order to improve the flatness or adhesion of the coating film, in addition to the above-described components.

When the photocurable ink composition according to the present invention includes a surfactant, there is an advantage that the flatness of the coating film can be improved. For example, the surfactant is BM-1000, BM-1100 (BM Chemie), Proride FC-135/FC-170C/FC-430 (Sumitomo 3M), SH-28PA/-190/-8400/SZ-6032 (Toray Silicone Co., Ltd.), Efka FL 3600 (BASF), etc. may be used, but the present invention is not limited thereto.

The adhesion promoter may include a silane coupling agent having a reactive substituent selected from the group consisting of a carboxyl group, a (meth)acryloyl group, an isocyanate group, an epoxy group, and combinations thereof, which may be added to increase adhesion with the substrate. However, the present invention is not limited thereto. For example, the silane coupling agent is trimethoxysilyl benzoic acid, γ-methacryloxypropyl trimethoxy silane, vinyltriacetoxysilane, vinyl trimethoxysilane, γ-isocyanate propyl triethoxysilane, γ-glycidoxy and propyl trimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and these may be used alone or in combination of two or more.

In addition to this, the photocurable ink composition according to the present invention may further include additives such as antioxidants, ultraviolet absorbers, and aggregation inhibitors within a range that does not impair the effects of the present invention, and the additives also do not impair the effects of the present invention. A person skilled in the art can use it by adding it appropriately to the range not included.

The additive may be used in an amount of 0.05 to 10% by weight, specifically 0.1 to 10% by weight, and more specifically 0.1 to 5% by weight based on 100% by weight of the total photocurable ink composition, but is not limited thereto.

The photocurable ink composition according to an embodiment of the present invention does not substantially include a solvent, and even if included, it is included in an amount of 10% by weight or less based on 100% by weight of the total photocurable ink composition. The photocurable ink composition according to an embodiment of the present invention is a solvent-free type that does not contain a solvent or a low-viscosity type that contains a very small amount of 5% by weight or less, for example 1% by weight or less.

In addition, the photocurable ink composition according to an embodiment of the present invention does not substantially include a resin component, and even if included, it contains within 1% by weight, preferably within 0.5% by weight, based on 100% by weight of the total photocurable ink composition. . The photocurable ink composition according to an exemplary embodiment of the present invention can realize low viscosity by not including a resin component, and thus has excellent nozzle jetting properties of the ink.

In addition, the photocurable ink composition according to an embodiment of the present invention may have excellent gas and moisture barrier properties after curing.

In addition, the photocurable ink composition according to the present invention may have an improved degree of curing and stability.

One embodiment of the present invention relates to an encapsulation layer including a cured product of the above-described photocurable ink composition.

The sealing layer serves to prevent oxidation or decomposition of the surface of the device member by an external environment such as moisture and oxygen by sealing the device member.

The method for forming a pattern of a photocurable ink composition according to the present invention comprises the steps of applying the above-described photocurable ink composition to a predetermined area by an inkjet method and curing the applied photocurable ink composition.

First, the photocurable ink composition of the present invention is injected into an inkjet injector and printed on a predetermined area of a device member.

In order to be ejected from a piezo inkjet head, which is an example of an inkjet injector, to form an appropriate phase on a member for an apparatus, properties such as viscosity and fluidity must be balanced with the inkjet head. The piezo inkjet head used in the present invention is not limited, but ejects ink having a droplet size of about 10 to 100 pL, preferably about 20 to 40 pL.

One embodiment of the present invention relates to an image display device including the above-described encapsulation layer.

The image display device may include a device member, and a barrier stack formed on the device member, the barrier stack including an inorganic encapsulation layer and an organic encapsulation layer, wherein the organic encapsulation layer is formed of the photocurable ink composition described above. includes cargo.

The device member may be decomposed, oxidized, or degraded when exposed to an external environment such as moisture and oxygen, and may include, for example, an organic light emitting device, a liquid crystal panel, and the like.

The device member may be formed on a substrate.

The substrate is not limited, and examples include a substrate with a flat surface, such as a glass substrate, a silicon substrate, a polycarbonate substrate, a polyester substrate, an aromatic polyamide substrate, a polyamideimide substrate, a polyimide substrate, an Al substrate, a GaAs substrate, etc. can These substrates can be subjected to pretreatment such as chemical treatment with a chemical such as a silane coupling agent, plasma treatment, ion plating treatment, sputtering treatment, gas phase reaction treatment, vacuum deposition treatment, and the like. When a silicon substrate or the like is used as the substrate, a charge coupled device (CCD), a thin film transistor (TFT), or the like may be formed on the surface of the silicon substrate or the like. In addition, a barrier rib matrix may be formed.

The inorganic encapsulation layer serves to protect the device member from external environments such as moisture and oxygen together with the organic encapsulation layer. The inorganic encapsulation layer has different components from the organic encapsulation layer, and includes an inorganic component as a main component. For example, the inorganic encapsulation layer may include silicon (Si), aluminum (Al), selenium (Se), zinc (Zn), antimony (Sb), indium (In), germanium (Ge), tin (Sn), and bismuth. (Bi), a transition metal, a metal such as a lanthanide metal or a non-metal; compounds between these metals or non-metals; alloys of these metals or non-metals; oxides of these metals or non-metals; nitrides of these metals or non-metals; oxynitrides of these metals or non-metals may be included.

The image display device may be an organic light emitting device (OLED), a liquid crystal display device (LCD), an electroluminescence display device (EL), a plasma display device (PDP), a field emission display device (FED), etc., but is not limited thereto. In particular, the image display device may be an organic light emitting device (OLED).

Hereinafter, the present invention will be described in more detail by way of Examples, Comparative Examples and Experimental Examples. These Examples, Comparative Examples, and Experimental Examples are only for illustrating the present invention, and it is apparent to those skilled in the art that the scope of the present invention is not limited thereto.

Examples and Comparative Examples: Preparation of photocurable ink composition

A photocurable ink composition was prepared by mixing each component in the composition of Tables 1 to 2 below (weight %).

Example One 2 3 4 5 6 7 8 9 10 11 12 13 Monofunctional photocurable monomer A-1 40 15 80 40 40 20 40 40 A-2 40 A-3 40 15 80 20 A-4 40 A-5 A-6 2-3 functional photocurable monomer B-1 35 35 35 35 40 10 40 10 35 35 20 B-2 35 15 B-3 35 B-4 20 20 20 20 40 5 40 5 20 20 10 20 B-5 20 10 photopolymerization initiator C-1 3 3 3 3 3 3 3 3 3 3 3 3 3 additive D-1 2 2 2 2 2 2 2 2 2 2 2 2 2

comparative example One 2 3 4 5 6 7 8 9 10 11 12 13 Monofunctional photocurable monomer A-1 5 9 85 30 50 30 55 5 A-2 A-3 5 9 85 A-4 A-5 40 A-6 40 2-3 functional photocurable monomer B-1 35 35 45 40 5 45 40 5 45 5 20 40 90 B-2 B-3 B-4 20 20 45 40 5 45 40 5 20 40 45 B-5 photopolymerization initiator C-1 3 3 3 9 3 3 9 3 3 3 3 3 3 additive D-1 2 2 2 2 2 2 2 2 2 2 2 2 2

A-1: dodecyl acrylate (TCI)

A-2: Stearyl Acrylate (TCI)

A-3: isobornyl acrylate (A-IB, Shin-Nakamura)

A-4: behenyl acrylate (A-BH, Shin-Nakamura)

A-5: ethyl acrylate

A-6: propyl acrylate

B-1: 1,4-bis (acryloyloxy) butane (TCI)

B-2: 1,6-hexanediol diacrylate (A-HD-N, Shin-Nakamura)

B-3: dipropylene glycol diacrylate (APG-100, Shin-Nakamura)

B-4: trimethylolpropane triacrylate (A-TMPT, Shin-Nakamura)

B-5: ethoxylated trimethylolpropane triacrylate (EO 3mol) (A-TMPT-3EO, Shin-Nakamura)

C-1: 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one (Igacure 369, BASF)

D-1: Efka FL 3600 (BASF)

Experimental example:

The following physical properties were evaluated using the photocurable ink compositions prepared in Examples and Comparative Examples in the following manner, and the results are shown in Table 3 below.

(1) Viscosity

The viscosity of each photocurable ink composition prepared in Examples and Comparative Examples was measured using a viscosity meter (DV3T, manufactured by Brookfield) (measurement conditions: rotation speed 20rpm/25°C).

(2) pencil hardness

Each of the photocurable ink compositions prepared in Examples and Comparative Examples was applied on a glass substrate by an inkjet method, and then, using a UV curing device (Lichtzen, Model No. LZ-UVC-F402-CMD), 150 mW/cm 2 A photocurable film was prepared by irradiating ultraviolet rays for 120 seconds at illuminance (based on UV-A region of 320 to 400 nm).

The pencil hardness of the prepared photocurable film was measured using a pencil hardness meter. Specifically, after a pencil (manufactured by Mitsubishi Corporation) was brought into contact with the photocurable film, the surface hardness was measured by scraping the surface at a load of 1 kg and a speed of 50 mm/sec.

(3) Inkjet characteristics

Each photocurable ink composition prepared in Examples and Comparative Examples was printed using an Omnijet 100 inkjet printer manufactured by Unijet. It was observed whether difficult jetting occurred during jetting. In addition, the organic film formation shape was observed after pattern printing in an area of 500 dpi, length × width (50 mm × 50 mm). Inkjet properties were evaluated according to the following evaluation criteria.

<Evaluation criteria>

○: During jetting, difficult jetting does not occur, and pinholes do not occur.

△: Some difficult jetting occurs during jetting, or two or less pinholes occur.

×: Severe jetting or 3 or more pinholes during jetting

(4) permittivity

Each photocurable ink composition prepared in Examples and Comparative Examples was coated on a P-type silicon wafer doped with boron to a thickness of 8 μm after curing, and then exposed under UV LED 395 nm. Then, using a hard mask designed to have a diameter of 1 mm, a circular aluminum thin film having a diameter of 1 mm was deposited to a thickness of 2000 Å to complete a thin film for measuring dielectric constant of a MIM (Metal-Insulator-Metal) structure. Capacitance of each of these thin films was measured at a frequency of about 100 kHz using a PRECISION LCR METER (HP4284A) equipped with a Micromanipulatior 6200 probe station. After measuring the thickness of the thin film with an ellipsometer, the dielectric constant was calculated by substituting it in Equation 1 below.

[Equation 1]

k = (C × A) / (εo × d)

In the above formula, k is the dielectric constant (dielectric ratio), C is the capacitance (capacitance), εo is the dielectric constant of vacuum (dielectric constant), d is the thickness of the thin film, A is the contact cross-sectional area of the electrode.

(5) Stability

The stability was evaluated according to the following evaluation criteria by calculating the rate of change of the viscosity after storage at 40° C. for 1 week compared to the initial viscosity of the photocurable ink compositions prepared in Examples and Comparative Examples.

<Evaluation criteria>

○: Viscosity change rate within 110%

△: Viscosity change rate greater than 110% and within 120%

×: Viscosity change rate more than 120%

Viscosity pencil hardness Inkjet Characteristics permittivity stability Example 1 24 H ○ 2.69 ○ Example 2 22 H ○ 2.62 ○ Example 3 27 H ○ 2.59 ○ Example 4 21 H ○ 2.53 ○ Example 5 29 2H ○ 2.81 ○ Example 6 24 H ○ 2.51 ○ Example 7 29 2H ○ 2.84 ○ Example 8 29 H ○ 2.61 ○ Example 9 24 H ○ 2.64 ○ Example 10 25 H ○ 2.71 ○ Example 11 27 H ○ 2.51 ○ Example 12 26 H ○ 2.67 ○ Example 13 24 H ○ 2.90 ○ Comparative Example 1 18 B △ 3.55 △ Comparative Example 2 20 B △ 3.51 △ Comparative Example 3 38 H △ 3.21 ○ Comparative Example 4 37 H △ 3.11 ○ Comparative Example 5 8 2B × 2.55 ○ Comparative Example 6 38 H △ 3.07 ○ Comparative Example 7 37 H △ 3.05 ○ Comparative Example 8 8 2B × 2.51 ○ Comparative Example 9 32 H △ 2.89 ○ Comparative Example 10 39 2H △ 2.63 ○ Comparative Example 11 41 2H △ 2.83 ○ Comparative Example 12 9 2B △ 2.65 ○ Comparative Example 13 9 2B × 3.10 ○

As shown in Table 3 above, the photocurable ink compositions of Examples 1 to 13 containing a monofunctional photocurable monomer having a specific structure in a specific content according to the present invention have a dielectric constant of a cured film of 3.0 or less, indicating a low dielectric constant, and a low point It is also possible to implement, and it was confirmed that the inkjet characteristics were also excellent. In addition, it was confirmed that the photocurable ink compositions of Examples 1 to 13 containing a monofunctional photocurable monomer having a specific structure in a specific content according to the present invention had excellent curing degree, improved pencil hardness, and excellent stability over time.

On the other hand, the photocurable ink compositions of Comparative Examples 1 to 8 and 13 which do not contain the monofunctional photocurable monomer having a specific structure in a specific content have a dielectric constant of a cured film greater than 3.0 or poor inkjet properties. In addition, the photocurable ink compositions of Comparative Examples 9 to 12, in which the content of the 2- to trifunctional photocurable monomer was outside the specific content range, showed poor inkjet properties.

As the specific part of the present invention has been described in detail above, for those of ordinary skill in the art to which the present invention pertains, it is clear that these specific techniques are only preferred embodiments, and the scope of the present invention is not limited thereto. do. Those of ordinary skill in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above contents.

Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (8)

It contains a compound of Formula 1 below, a 2- to trifunctional photocurable monomer, and a photopolymerization initiator,
The photocurable ink composition wherein the compound of Formula 1 is included in an amount of 10 to 80% by weight based on 100% by weight of the total composition:
[Formula 1]

In the above formula,
R ¹ is hydrogen or a methyl group,
R ² is a C ₅ -C ₃₀ alkyl group or a C ₅ -C ₃₀ cycloalkyl group. The photocurable ink composition according to claim 1, wherein the viscosity at 25°C is 10 to 30 cP, and the dielectric constant of the cured film is 3.0 or less. The photocurable ink composition of claim 1, wherein the 2- to trifunctional photocurable monomer comprises at least one of compounds represented by the following Chemical Formulas 2-1 to 2-3:
[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

In the above formula,
R ¹ is each independently hydrogen or a methyl group,
R ³ is hydrogen or a C ₁ -C ₃ alkyl group,
R ⁴ is hydrogen, a hydroxyl group, a C ₁ -C ₃ alkyl group or a C ₁ -C ₃ alkoxy group,
L is a C ₂ -C ₂₀ alkylene group,
n is each independently an integer from 0 to 10; According to claim 3, 10 to 80% by weight of the compound of Formula 1, 10 to 40% by weight of the difunctional photocurable monomer, and 5 to 40% by weight of the trifunctional photocurable monomer, based on 100% by weight of the total photocurable ink composition A photocurable ink composition. The photocurable ink composition according to claim 1, wherein the solvent is contained in an amount of 1 wt% or less. The photocurable ink composition according to claim 1, which is used for encapsulating an organic light emitting device. An encapsulation layer comprising a cured product of the photocurable ink composition according to any one of claims 1 to 6. An image display device comprising the encapsulation layer according to claim 7.