KR102311852B1 - Photocurable composition and photocured layer formed from the same - Google Patents

Abstract

Embodiments of the present invention include a dithiol compound, a difunctional or more unsaturated polymerizable compound, and a photoinitiator, and provide a photocurable composition having a viscosity of 15cp or less at room temperature. A photocurable film having high-density crosslinking properties can be formed from the photocurable composition through low-viscosity fine printing.

Description

Photocurable composition and photocurable film formed therefrom

The present invention relates to a photocurable composition and a photocurable film formed therefrom. More particularly, it relates to a photocurable composition comprising photopolymerizable monomers and a photocurable film formed therefrom.

For example, the photosensitive composition is used to form various photocurable insulating patterns such as photoresist, insulating film, protective film, black matrix, column spacer, etc. of a display device. After the photosensitive composition is applied, a photocurable film or a photocurable pattern having a predetermined shape may be formed in a desired area through an exposure process and/or a developing process. The photosensitive composition has, for example, high sensitivity to ultraviolet light exposure and polymerization reactivity, and a pattern formed therefrom needs to have improved heat resistance, chemical resistance, and the like.

For example, in an organic light emitting diode (OLED) display device, an organic light emitting layer may be formed for each pixel, and an encapsulation layer may be formed to protect the organic light emitting layer from external impurities or moisture. In addition, the encapsulation layer may be provided as a protective layer of the electrode wirings of the display device.

An inorganic insulating layer including silicon oxide, silicon nitride, and/or silicon oxynitride may be formed as the encapsulation layer. However, the inorganic insulating layer alone may not sufficiently block deterioration of the display device due to external moisture.

Therefore, a protective film containing an organic component needs to be employed. In this case, it may be considered to form an encapsulation layer using the photosensitive organic composition.

Recently, as the resolution of OLED devices increases, patterns and pixel sizes are also being miniaturized. Accordingly, the photosensitive organic composition also needs to have properties suitable for fine application or fine patterning. For example, as the viscosity of the photosensitive organic composition increases, fine application may become more difficult, and the non-uniformity of the profile of the formed coating film may worsen.

For example, Korea Patent No. 10-1359470 includes an alkali-soluble resin, a photocurable monomer, a photopolymerization initiator, an aminoacetophenone- or aminobenzaldehyde-based hydrogen donor and a solvent, and by activating the alkyl radical generated in the photopolymerization initiator Disclosed is a photosensitive resin composition capable of improving photoreactivity.

However, when an alkali-soluble resin is included, the viscosity of the composition increases, thereby limiting the implementation of desired fine patterning.

Korean Patent No. 10-1359470

One object of the present invention is to provide a photocurable composition having a low viscosity and an improved degree of crosslinking.

One object of the present invention is to provide a photocurable film formed from the photocurable composition and having improved hardness and uniformity.

An object of the present invention is to provide an image display device including the photocurable film.

1. dithiol compounds; difunctional or higher functional unsaturated polymerizable compound; And comprising a photoinitiator, the viscosity at room temperature is 15cp or less, the photocurable composition.

2. The photocurable composition according to the above 1, wherein the dithiol compound comprises an ethylene oxide linker group or an alkylene linker group.

3. The photocurable composition according to the above 1, wherein the dithiol compound comprises at least one of the compounds represented by the following Chemical Formula 1 or Chemical Formula 2:

[Formula 1]

(in Formula 1, m is an integer of 1 to 5)

[Formula 2]

(in Formula 2, n is an integer of 1 to 11).

4. The photocurable composition according to the above 1, wherein the unsaturated polymerizable compound comprises an ethoxylated (meth)acrylate compound.

5. The photocurable composition according to the above 1, wherein the unsaturated polymerizable compound comprises at least one selected from the group consisting of compounds represented by the following Chemical Formulas 3 to 6:

[Formula 3]

(In Formula 3, R ₁ is hydrogen or a methyl group, and m is an integer of 1 to 10)

[Formula 4]

(In Formula 4, R ₂ is each independently hydrogen or a methyl group, R ₃ is hydrogen or an alkyl group having 1 to 3 carbon atoms, and n is an integer of 1 to 5)

[Formula 5]

[Formula 6]

(In Formulas 5 and 6, R ₄ is hydrogen or a methyl group, R _a is hydrogen, an alkyl group having 1 to 3 carbon atoms, a hydroxyl group (-OH), or an alkoxy group having 1 to 3 carbon atoms. p is 1 to 5 integer).

6. The photocurable composition according to the above 1, wherein the unsaturated polymerizable compound comprises a combination of a bifunctional (meth)acrylate compound and a trifunctional (meth)acrylate compound.

7. The photocurable composition of 1 above, further comprising a surfactant.

8. The method of 7 above, based on the total weight of the composition, 5 to 20% by weight of the dithiol compound; 60 to 90% by weight of the unsaturated polymerizable compound; 1 to 10% by weight of the photoinitiator; and 1 to 10% by weight of the surfactant.

9. The photocurable composition according to 1 above, which is prepared in a solvent-free type.

10. The photocurable composition of 1 above, which does not contain a polymer or resin component.

11. A photocurable film formed from the photocurable composition of any one of 1 to 10 above.

12. As in 11 above, 150 N/mm ² A photocurable film having the above Martens Hardness.

13. An image display device comprising a photocurable film formed from the photocurable composition of any one of 1 to 10 above.

14. The image display device according to the above 13, wherein the photocurable film is provided as an encapsulation layer of a wiring or a light emitting element.

According to embodiments of the present invention, while controlling the overall viscosity of the composition to about 15cp or less, a photocurable composition capable of implementing both a low viscosity and an improved degree of crosslinking is provided.

The photocurable composition may include a dithiol compound and an unsaturated polymerizable compound having a dithiol function or higher, and a decrease in active species of the unsaturated polymerizable compound due to oxygen inhibition by the dithiol compound may be prevented. Accordingly, the dithiol compound is substantially provided as a crosslinking accelerator, and a sufficient degree of crosslinking and curing can be realized even if a separate resin component is not included.

The photocurable composition does not include a resin component and may be used in a solvent-free type. Accordingly, a low-viscosity composition is implemented without including a solvent, and fine patterning can be effectively implemented, for example, through inkjet coating. In addition, since the solvent component is excluded, the instability over time according to the composition component change due to solvent volatilization can be significantly improved.

The photocurable film formed using the photocurable composition according to embodiments of the present invention has excellent gas and moisture barrier properties, and has improved flexibility, so it can be utilized as an encapsulation layer of a flexible display device, for example.

1, 2, and 3 are schematic cross-sectional views illustrating an image display device including a photocurable film according to embodiments of the present invention.
4 is a schematic plan view for explaining a coating flatness measurement method in the present experimental example.
5 and 6 are images for explaining the evaluation criteria of the surface hardening degree of the photocurable film of Examples and Comparative Examples, respectively.

Embodiments of the present invention, a photocurable composition comprising a dithiol compound, a difunctional or more unsaturated polymerizable compound and a photoinitiator, and having a low viscosity and improved hardness and barrier properties, and a photocurable film formed therefrom do.

Hereinafter, embodiments of the present invention will be described in detail.

<Photocurable composition>

dithiol compounds

The allyl ether compound included in the photocurable composition according to embodiments of the present invention substantially lowers the viscosity of the composition, and may function as a diluent. The dithiol compound may replace the solvent included in the compositions for forming a general photosensitive organic layer. Accordingly, according to exemplary embodiments, the photocurable composition may be prepared and utilized in a substantially solvent-free or non-solvent type.

The dithiol compound may have high solubility in other components of the composition to be described later, and may have reactivity that may participate in polymerization or curing together with the unsaturated polymerizable compound.

According to exemplary embodiments, the dithiol compound may include two thiol groups bonded to the end of the linker group. In some embodiments, the linker group may include an ethylene oxide (EO) group or an alkylene group.

In one embodiment, the dithiol compound including the EO linker group may be represented by the following formula (1).

[Formula 1]

In Formula 1, m may be an integer of 1 to 5. When m is an integer of 6 or more, the viscosity of the composition may increase excessively.

In one embodiment, the dithiol compound including the alkylene linker group may be represented by the following formula (2).

[Formula 2]

In Formula 2, n may be an integer of 1 to 11. When n is an integer of 12 or more, the viscosity of the composition may increase excessively.

Preferably, n may be 6 to 10. When n is reduced and the length of the alkylene linker group is shortened, harm to the human body or the environment may be caused by sulfur (S) having odor.

In some embodiments, as exemplarily described in Formulas 1 and 2, the linker group may have a linear structure and may not include a branch. Therefore, crosslinking promoting properties due to steric hindrance according to the branch structure may not be inhibited. In addition, by having a linear structure, dilution characteristics and low viscosity characteristics through the dithiol compound may be more effectively implemented.

The dithiol compound may be provided as an agent that promotes or activates crosslinking and curing of an unsaturated polymerizable compound, which will be described later. For example, radically active species (eg, peroxy radicals) are generated through an initiation reaction between a photoinitiator and the unsaturated polymerizable compound, and crosslinking or polymerization reaction is performed by a chain reaction by the radically active species. can proceed.

However, when the radically active species meets oxygen penetrating into the composition or coating film in the atmosphere, the radical activity is extinguished and the crosslinking or polymerization reaction may be terminated.

In this case, according to exemplary embodiments, the dithiol compound may react with the extinct radical active species to revive radical activity. Therefore, a desired cross-linking network can be formed without being affected by external oxygen inhibition.

In some embodiments, the photocurable composition may include only a dithiol compound as a thiol compound, and may not include a monofunctional thiol or a trifunctional or more functional thiol compound.

When the monofunctional thiol compound is used, it is difficult to sufficiently implement the above-described radically active species revitalizing effect, and the hardness and barrier properties of the photocurable film may be deteriorated.

When the trifunctional or higher thiol compound is included, the composition viscosity may increase rapidly. In the case of a trifunctional or higher polyfunctional thiol compound, for example, it is synthesized from a starting material such as 3-mercaptopropionic acid, and in this case, it contains a plurality of ester bonds or carboxyl groups in the molecule.

Accordingly, the viscosity of the thiol compound and the viscosity of the composition may rapidly increase due to intermolecular or intramolecular interactions such as hydrogen bonding by the ester bond or carboxyl group.

In addition, in the case of a polyfunctional thiol compound having a trifunctional or higher function, since it deviates from a linear structure, a three-dimensional interaction of the thiol compounds itself may be caused, thereby additionally increasing the composition viscosity.

However, according to exemplary embodiments of the present invention, by using a linear difunctional thiol compound (dithiol compound), the effect of promoting crosslinking and reducing viscosity can be effectively satisfied at the same time.

According to exemplary embodiments, the content of the dithiol compound in the total weight of the photocurable composition may be about 5 to 20% by weight. When the content of the dithiol compound is less than about 5% by weight, the above-described effects of blocking oxygen inhibition and promoting crosslinking may not be sufficiently implemented. In addition, a sufficient diluent may not be provided, which may decrease the solubility of other components and increase the viscosity.

When the content of the dithiol ether compound exceeds about 20% by weight, the content of the unsaturated polymerizable compound to be described later may be relatively decreased, thereby deteriorating the degree of curing and mechanical properties.

Preferably, the content of the dithiol compound may be about 5 to 10% by weight.

Unsaturated polymeric compounds

The photocurable composition according to embodiments of the present invention may include, for example, an unsaturated polymerizable compound as a main component for forming a crosslinking network by participating in a radical polymerization reaction by an ultraviolet exposure process.

The unsaturated polymerizable compound may include a bifunctional unsaturated ethylenic monomer, for example, may include a (meth)acrylate compound having a bifunctional or higher function.

As used herein, the term "(meth)acryl-" is used to refer to "methacryl-", "acryl-", or both.

The double bond of the unsaturated polymerizable compound may serve as a cross-linking point at which initiation of radical photopolymerization through, for example, UV curing occurs. The crosslinking point may be provided, for example, as a mesh of a photocurable film network formed from the photocurable composition.

Therefore, by using a bifunctional or more unsaturated polymerizable compound, the density or number of the meshes is increased. A barrier effect against external moisture and oxygen through the photocurable film may be increased.

In addition, as described above, through the interaction between the unsaturated polymerizable compound and the dithiol compound, the crosslinking reaction may be maintained until a desired hardness is secured without loss due to oxygen inhibition of the crosslinking point.

In some embodiments, the unsaturated polymerizable compound may include a bifunctional (meth)acrylate compound and/or a trifunctional (meth)acrylate compound.

For example, the bifunctional (meth)acrylate compound may include at least one of compounds represented by the following Chemical Formula 3 or Chemical Formula 4.

[Formula 3]

In Formula 3, R ₁ may be hydrogen or a methyl group. m may be an integer from 1 to 10.

[Formula 4]

In Formula 4, R ₂ may each independently be hydrogen or a methyl group. R ₃ may be hydrogen or an alkyl group having 1 to 3 carbon atoms. n may be an integer from 1 to 5.

For example, the trifunctional (meth)acrylate compound may include at least one of compounds represented by the following Chemical Formula 5 or Chemical Formula 6.

[Formula 5]

[Formula 6]

In Formulas 5 and 6, R ₄ may be hydrogen or a methyl group. R _a may be hydrogen, an alkyl group having 1 to 3 carbon atoms, a hydroxyl group (-OH), or an alkoxy group having 1 to 3 carbon atoms. p may be an integer from 1 to 5.

In Formulas 5 and 6, p and R ₄ are included in common, but are not used to mean the same as each other, and may be independently controlled in each Formula.

As shown in Formulas 3 to 6, the (meth)acrylate functional groups included in the unsaturated polymerizable compound may be bonded by a linear alkylene or EO linker group (eg, an ethoxylated structure). .

Therefore, since the unsaturated polymerizable compound has a structure rotatable by the linker group, it has uniform mixing characteristics without a solvent and the flexibility of the photocurable film network can be improved.

In some embodiments, the sum of the functional numbers of the unsaturated polymerizable compound may be 5. As used herein, the term “sum of functional numbers” refers to the sum of functional numbers included when categorizing (meth)acrylate compounds included in the unsaturated polymerizable compound by the number of functional groups.

In an embodiment, as the unsaturated polymerizable compound, a bifunctional (meth)acrylate compound and a trifunctional (meth)acrylate compound may be used together. In this case, while lowering the viscosity of the composition by the bifunctional (meth) acrylate compound, the desired barrier properties and degree of curing can be realized while ensuring a sufficient crosslinking point through the trifunctional (meth) acrylate compound.

In some embodiments, the unsaturated polymerizable compound may not include a tetrafunctional or higher (meth)acrylate compound. In the case of the tetrafunctional or higher (meth)acrylate compound, the viscosity of the composition may be rapidly increased due to intermolecular interaction due to the bulky molecular structure.

According to exemplary embodiments, the content of the unsaturated polymerizable compound in the total weight of the photocurable composition may be about 60 to 90% by weight. When the content of the polycyclic hydrocarbon-containing (meth)acrylate compound is less than about 60% by weight, the hardness and mechanical properties of the cured film may be deteriorated. When the content of the polycyclic-containing (meth)acrylate compound exceeds about 90% by weight, the viscosity of the composition increases excessively, so that the coating device (eg, inkjet device) is clogged, and the leveling properties of the photocurable film may be deteriorated. have.

In some embodiments, when the bifunctional (meth)acrylate compound and the trifunctional (meth)acrylate compound are used together, the bifunctional ( The content of the meth)acrylate compound may be greater than the content of the trifunctional (meth)acrylate compound.

photoinitiator

According to exemplary embodiments, the photoinitiator may be used without particular limitation as long as it can induce a reaction of the above-described unsaturated polymerizable compound by generating radically active species by an exposure process. As described above, the polymerizable double bonds included in the unsaturated polymerizable compound may act as a crosslinking point by radically active species generated through the photoinitiator to form a high-density network.

For example, as the photoinitiator, at least one compound selected from the group consisting of an acetophenone-based compound, a benzophenone-based compound, a triazine-based compound, a biimidazole-based compound, a thioxanthone-based compound, and an oxime ester-based compound may be used. and, preferably, an oxime ester-based compound may be used.

As the oxime ester-based photoinitiator, at least one or more of the compounds represented by the following Chemical Formulas 7-1 to 7-3 may be used.

[Formula 7-1]

[Formula 7-2]

[Formula 7-3]

In Formulas 7-1 to 7-3, R ₅ , R _{6 ,} R ₈ , R _{9 ,} and R ₁₀ may each independently be hydrogen or an alkyl group having 1 to 10 carbon atoms. R ₇ may be an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, or an aryl group.

According to exemplary embodiments, the content of the photoinitiator based on the total weight of the photocurable composition may be about 1 to 10% by weight, preferably about 1 to 5% by weight. It is possible to improve the resolution of the exposure process and the hardness of the cured film without increasing the viscosity of the composition in the above range.

additive

Additional agents may be further included to improve polymerization properties, degree of curing, and surface properties of the cured film formed from the photocurable composition, and to realize low viscosity. For example, additives may be further included within a range that does not impair low-viscosity properties, hardness, and flexibility of the photocurable composition according to embodiments of the present invention.

In some embodiments, the photocurable composition may further include a surfactant, and the surfactant may be further added to improve the coating uniformity of the composition and the surface uniformity of the cured film. In addition, compatibility of each component of the composition according to exemplary embodiments prepared in a solvent-free type may be increased.

The surfactant may be a nonionic surfactant, a cationic surfactant, an anionic surfactant, etc. widely used in the art. For example, the surfactant may be included in an amount of about 1 to 10% by weight based on the total weight of the photocurable composition.

On the other hand, additives such as antioxidants, leveling agents, curing accelerators, ultraviolet absorbers, aggregation inhibitors, and chain transfer agents may be further added to further improve the properties such as curing degree, smoothness, adhesion, solvent resistance, and chemical resistance of the photocurable film. have.

The photocurable composition according to the above-described exemplary embodiments of the present invention may be prepared in a substantially non-solvent or solvent-free type. In addition, the photocurable composition is substantially composed of monomers, and may not include a polymer or resin component.

Therefore, for example, a low-viscosity composition capable of a coating process without a solvent without clogging a nozzle through an inkjet process may be implemented. In addition, while the dithiol compound is substantially provided as a diluent or solvent, the crosslinking reaction of the unsaturated polymerizable compound is activated to obtain a photocurable film having sufficient barrier properties without a polymer/resin component. In addition, variations in content/composition due to volatilization of the solvent can be prevented.

According to exemplary embodiments, the viscosity of the photocurable composition may be 15 cp or less, preferably 10 cp or less at room temperature (eg, 25° C.).

<Photocurable film and image display device>

The present invention provides a photocurable film prepared from the above-described photocurable composition and an image display device including the photocurable film.

The photocurable film may be used as various film structures or patterns of an image display device, for example, an adhesive layer, an array planarization film, a protective film, an insulating film pattern, etc., a photoresist, a black matrix, a column spacer pattern, a black column spacer pattern, etc. may be used, but is not limited thereto.

In forming the photocurable film, the above-described photocurable composition may be applied on a substrate to form a coating film. Examples of the coating method include inkjet printing, spin coating, cast coating method, roll coating method, slit and spin coating, or slit coating method.

Thereafter, a photocurable film may be formed by performing an exposure process, and a post exposure baking (PEB) process may be further performed. In the exposure process, an ultraviolet light source such as a UV-A region (320 to 400 nm), a UV-B region (280 to 320 nm), or a UV-C region (200 to 280 nm) of a high-pressure mercury lamp may be used. In an embodiment, a developing process may be further performed to pattern the photocurable film.

In example embodiments, the photocurable film may have a Martens Hardness of about 150 N/mm ^{2 or} more. Martens hardness value of approx. 150 N/mm ² If it is less than, the strength and mechanical durability of the photocurable film may be deteriorated. In one embodiment, the Martens hardness value may be about 150 to 200N/mm ² to prevent excessive increase in brittle characteristics of the photocurable film.

In example embodiments, the encapsulation layer of the light emitting layer included in the OLED device may be formed through inkjet printing using the photocurable composition.

1, 2, and 3 are schematic cross-sectional views illustrating an image display device including a photocurable film according to embodiments of the present invention. For example, FIGS. 1 to 3 show an image display device using the photocurable film as an encapsulation layer of an organic light emitting diode.

Referring to FIG. 1 , the image display device may include a base substrate 100 , a pixel defining layer 110 , an organic light emitting diode 120 , and an encapsulation layer 140 .

The base substrate 100 may serve as a support substrate or a back-plane substrate of the image display device. For example, the base substrate 100 may be a glass or plastic substrate, and in some embodiments, may include a flexible resin material such as polyimide. In this case, the image display device may be provided as a flexible OLED display.

A pixel defining layer 110 may be formed on the base substrate 100 to expose each pixel in which a color or an image is implemented. A thin film transistor (TFT) array may be formed between the base substrate 100 and the pixel defining layer 110 , and an insulating structure covering the TFT array may be formed. The pixel defining layer 110 may be formed on the insulating structure, and may expose a pixel electrode (eg, an anode) that passes through the insulating structure and is electrically connected to the TFT.

The organic light emitting diode 120 may be formed in each pixel area exposed by the pixel defining layer 110 . The organic light emitting device 120 may include, for example, the pixel electrode, the organic light emitting layer, and the opposite electrode sequentially stacked.

The organic light emitting layer may include an organic light emitting material known in the art for red, green, and blue light emission. A hole transport layer (HTL) may be further formed between the pixel electrode and the organic emission layer, and an electron transport layer (ETL) may be further formed between the organic emission layer and the counter electrode. The counter electrode may serve as, for example, a cathode. The opposite electrode may be patterned for each pixel area or may be provided as a common electrode for a plurality of organic light emitting devices. The organic light emitting layer or the organic light emitting device 120 may be formed through, for example, an inkjet printing process.

The encapsulation layer 140 may partially cover the pixel defining layer 110 while covering the organic light emitting diode 120 . The encapsulation layer 140 may function as, for example, a moisture and oxygen barrier pattern of the organic light emitting diode 120 .

The encapsulation layer 140 may be formed using a photocurable composition according to example embodiments. As described above, the photocurable composition may have a solvent-free type and a low viscosity capable of inkjet printing. For example, the photocurable composition may have a viscosity of about 15 cp or less. Accordingly, it is possible to obtain the encapsulation layer 140 having excellent leveling characteristics and finely printed or patterned even in a high-resolution pixel structure.

As shown in FIG. 1 , the encapsulation layer 140 may be patterned for each pixel, and has a high-density network structure through the synergistic effect of the unsaturated polymerizable compound and the dithiol compound included in the photocurable composition. and the encapsulation layer 140 having flexibility may be formed. Thus, for example, the encapsulation layer 140 effectively employable in a flexible OLED device can be formed.

Additional structures such as a polarizing film, a touch sensor, and a window substrate may be stacked on the encapsulation layer 140 .

Referring to FIG. 2 , the encapsulation layer 143 may be formed in the form of a film that commonly covers the pixel defining layer 110 and the plurality of organic light emitting devices 120 .

Referring to FIG. 3 , the encapsulation layer may have a multilayer structure including a first encapsulation layer 130 and a second encapsulation layer 145 .

The first encapsulation layer 130 may be formed of, for example, an inorganic insulating material such as silicon oxide, silicon nitride, and/or silicon oxynitride. The second encapsulation layer 145 may be formed using a photocurable composition according to exemplary embodiments of the present invention. Accordingly, the encapsulation layer may be provided in the form of an organic/inorganic hybrid film.

1 to 3 illustrate that the photocurable film is used as the OLED encapsulation layer according to exemplary embodiments, but the use of the photocurable film is not necessarily limited thereto.

For example, the photocurable film may be used as an encapsulation layer of an electrode or wiring of a display device to provide an excellent moisture and oxygen barrier to prevent corrosion of the electrode or wiring.

In addition, the photocurable film may be used as an encapsulation layer for a pixel portion or a light emitting device of various display devices such as an LCD device as well as an OLED device.

Hereinafter, experimental examples including preferred examples and comparative examples are presented to help the understanding of the present invention, but these examples are merely illustrative of the present invention and do not limit the appended claims, It is obvious to those skilled in the art that various changes and modifications can be made to the embodiments within the scope and spirit of the present invention, and it is natural that such variations and modifications fall within the scope of the appended claims.

Examples and Comparative Examples

Photocurable compositions according to Examples and Comparative Examples were prepared with the components and contents shown in Tables 1 and 2 below.

Category (wt%) Example One 2 3 4 5 6 7 unsaturated
polymeric
compound
(acryl
rate system)
(A) A-1 47.08 47.08 47.08 47.08 47.08 37.66 56.50 A-2 37.66 37.66 37.66 37.66 37.66 47.08 - A-3 - - - - - - 28.25 A-4 - - - - - - - thiol
compound
(B) B-1 9.42 - - - - 9.42 9.41 B-2 - 9.42 - - - - - B-3 - - 9.42 - - - - B-4 - - - 9.42 - - - B-5 - - - - 9.42 - - B-6 - - - - - - - B-7 - - - - - - - B-8 - - - - - - - photoinitiator
(C) 3.77 3.77 3.77 3.77 3.77 3.77 3.77 Surfactants
(D) 2.07 2.07 2.07 2.07 2.07 2.07 2.07

Category (wt%) comparative example One 2 3 4 5 unsaturated
polymeric
compound
(acryl
rate system)
(A) A-1 56.50 47.08 47.08 - 47.08 A-2 37.66 37.66 37.66 - 37.66 A-3 - - - - - A-4 - - - 84.74 - thiol
compound
(B) B-1 - - - 9.42 - B-2 - - - - - B-3 - - - - - B-4 - - - - B-5 - - - - - B-6 - 9.42 - - - B-7 - - 9.42 - - B-8 - - - - 9.42 photoinitiator
(C) 3.77 3.77 3.77 3.77 3.77 Surfactants
(D) 2.07 2.07 2.07 2.07 2.07

Specific components or compounds listed in Tables 1 and 2 are as follows.

A-1: 1,4-butanediol diacrylate (Viscoat#195: manufactured by Daepan Organic Co., Ltd.)

A-2: ethoxylated trimethylolpropane triacrylate (A-TMPT-3EO: manufactured by Shin-Nakamura Chemical Co., Ltd.)

A-3: ethoxylated pentaerythritol tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.)

A-4: Lauryl acrylate (NK ESTER LA: manufactured by Shin-Nakamura Chemical Co., Ltd.)

B-1: 2,2'-(ethylenedioxy)diethanethiol (manufactured by TCI)

B-2: tetra (ethylene glycol) dithiol (manufactured by TCI)

B-3: 1,10-decanedithiol (manufactured by TCI)

B-4: 1,8-octanedithiol (manufactured by Sigma-Aldrich)

B-5: 1,6-hexanedithiol (manufactured by Sigma-Aldrich)

B-6: dodecanethiol (manufactured by Sigma-Aldrich)

B-7: 1,4-bis(3-mercaptobutyryloxy)butane (Karenz MT BD1: manufactured by Showa Denko)

B-8: trimethylolpropane tris(3-mercaptopropionate) (manufactured by Sigma-Aldrich)

C: Oxime ester compound represented by Formula 8

[Formula 8]

D: UVK-3500 (manufactured by BYK)

Experimental example

Viscosity, coating flatness, surface hardening properties, and Martens hardness of the compositions of Tables 1 and 2 or the photocurable film formed therefrom were evaluated through the evaluation method to be described later.

(1) Viscosity measurement

The viscosity of the compositions of Examples and Comparative Examples was measured using a viscosity meter (DV3T; Brookfield Co., Ltd.) (Measurement conditions: 20rpm/25℃)

(2) coating flatness

4 is a schematic plan view for explaining a coating flatness measurement method in the present experimental example.

After curing the compositions of Examples and Comparative Examples on a 4-inch silicon wafer, respectively, spin coating to a film thickness of 1.5 μm to form a coating film, 30 using a UV curing device (Model No. LZ-UVC-F402-CMD) After irradiating ultraviolet rays for a second, the film thickness was measured.

As shown in FIG. 4, the difference between the maximum and minimum values of the film thicknesses measured using an optical (non-contact) film thickness meter (Lambda Ace VM-1210, Dainippon Screen MFG Co.) at 33 points on the wafer was measured. The thickness deviation was confirmed by calculation.

(3) surface hardening degree

The photocurable compositions of Examples and Comparative Examples were respectively applied on a silicon wafer cut to a size of 50mm X 50mm, and after curing, the photocurable compositions were spin-coated to a film thickness of 3.0㎛, and then placed in an acrylic case and replaced with a nitrogen atmosphere. Then, using a UV curing device (Lichtzen, Model No. LZ-UVC-F402-CMD) was irradiated with UV light for 30 seconds at an illuminance of 150 mW/cm 2 (based on UV-A region 320 to 400 nm) to form a photocurable film. . By rubbing the photocurable film with a latex glove, it was confirmed whether the crosslinking reaction proceeded well by checking the change of the surface.

5 and 6 are images for explaining the evaluation criteria of the surface hardening degree of the photocurable film of Examples and Comparative Examples. 5 and 6 are exemplary images for explaining the evaluation criteria, and do not limit the actual evaluation results.

<Evaluation criteria>

○: Substantially no change in the surface of the coating film (refer to FIG. 5)

×: Scratches of the coating film were observed (refer to FIG. 6)

(4) Measurement of Martens Hardness

A photocurable film was formed using the compositions of Examples and Comparative Examples in substantially the same manner as in evaluating the degree of surface hardening.

Martens hardness of the formed photocurable film was measured using a nanoindenter (manufactured by Fischer Technology, Inc.) equipment. Specifically, in accordance with the international standard ISO 14577-1, the load section not affected by the lower substrate was confirmed using the equipment equipped with the Vickers indenter. That is, the loading value is checked through the data of the section where the indenter presses the coating film and the incoming displacement (Depth) is the minimum, and after setting the photocurable film formed using this to 1.0mN, the Martens hardness (N/mm ² ) The values were measured.

The evaluation results are shown in Tables 3 and 4 below.

division Example One 2 3 4 5 6 7 compositional viscosity
(cp = mPas) 9.5 10.3 9.5 9.0 8.2 11.1 9.8 coating flatness
(thickness deviation) (Å) 1105 973 1113 985 1205 1288 1301 Surface hardening properties ○ ○ ○ ○ ○ ○ ○ Martens hardness (HM: N/mm ² ) 168 166 158 162 169 175 167

division comparative example One 2 3 4 5 compositional viscosity
(cp = mPas) >30 8.2 22 8.1 27 coating flatness
(thickness deviation) (Å) 3240 1367 2171 1354 2130 Surface hardening properties ○ × ○ × ○ Martens hardness (HM: N/mm ² ) 147 uncured 137 uncured 168

Referring to Tables 3 and 4, in the case of Examples using a dithiol compound and a bifunctional or more unsaturated polymerizable compound, overall excellent flatness and curing/hardness were obtained, and a viscosity of 15cp or less was obtained.

In Comparative Example 1 in which the thiol compound was omitted, the composition viscosity increased rapidly, and in Comparative Example 5 in which the trifunctional thiol compound was used, the composition viscosity also significantly increased. In addition, Comparative Example 3 in which a thiol compound containing an ester bond was used also had a viscosity exceeding 20 cp.

In Comparative Examples 3 and 4 in which the monothiol compound and the monofunctional acrylate were used, respectively, a substantially effective cured film was not obtained.

100: base substrate 110: pixel defining layer
120: organic light emitting device 130: first encapsulation layer
140, 143: encapsulation layer 145: second encapsulation layer

Claims (14)

dithiol compounds;
difunctional or higher functional unsaturated polymerizable compound; and
a photoinitiator;
The viscosity at room temperature is 15 cp or less,
The unsaturated polymerizable compound includes a combination of a bifunctional (meth)acrylate compound and a trifunctional (meth)acrylate compound, and does not include a tetrafunctional (meth)acrylate compound,
The content of the bifunctional (meth) acrylate compound is greater than the content of the trifunctional (meth) acrylate compound,
A photocurable composition prepared in a solvent-free type.
The photocurable composition of claim 1, wherein the dithiol compound comprises an ethylene oxide linker group or an alkylene linker group.
The photocurable composition according to claim 1, wherein the dithiol compound comprises at least one of compounds represented by the following Chemical Formula 1 or Chemical Formula 2:
[Formula 1]

(in Formula 1, m is an integer of 1 to 5)
[Formula 2]

(in Formula 2, n is an integer of 1 to 11).
The photocurable composition of claim 1 , wherein the unsaturated polymerizable compound comprises an ethoxylated (meth)acrylate compound.
The photocurable composition according to claim 1, wherein the unsaturated polymerizable compound comprises at least one selected from the group consisting of compounds represented by the following Chemical Formulas 3 to 6:
[Formula 3]

(In Formula 3, R ₁ is hydrogen or a methyl group, and m is an integer of 1 to 10)
[Formula 4]

(In Formula 4, R ₂ is each independently hydrogen or a methyl group, R ₃ is hydrogen or an alkyl group having 1 to 3 carbon atoms, and n is an integer of 1 to 5)
[Formula 5]

[Formula 6]

(In Formulas 5 and 6, R ₄ is hydrogen or a methyl group, R _a is hydrogen, an alkyl group having 1 to 3 carbon atoms, a hydroxyl group (-OH), or an alkoxy group having 1 to 3 carbon atoms. p is 1 to 5 integer).
delete The photocurable composition of claim 1, further comprising a surfactant.
The method according to claim 7, wherein in the total weight of the composition,
5 to 20% by weight of the dithiol compound;
60 to 90% by weight of the unsaturated polymerizable compound;
1 to 10% by weight of the photoinitiator; and
A photocurable composition comprising 1 to 10% by weight of the surfactant.
delete The photocurable composition according to claim 1, which does not contain a polymer or resin component.
A photocurable film formed from the photocurable composition of any one of claims 1 to 5, 7, 8 and 10.
12. The method of claim 11, 150 N/mm ² A photocurable film having the above Martens Hardness.
An image display device comprising a photocurable film formed from the photocurable composition of any one of claims 1 to 5, 7, 8 and 10.
The image display device according to claim 13, wherein the photocurable film is provided as an encapsulation layer of a wiring or a light emitting element.

Images