CN117204120A

CN117204120A - Curable composition and organic EL display device

Info

Publication number: CN117204120A
Application number: CN202280030215.0A
Authority: CN
Inventors: 馆野航太郎
Original assignee: Mitsui Chemicals Inc
Current assignee: Mitsui Chemicals Inc
Priority date: 2021-04-28
Filing date: 2022-04-21
Publication date: 2023-12-08
Also published as: KR20230158588A; TW202248269A; JPWO2022230748A1; WO2022230748A1

Abstract

The present invention provides a curable composition which is a liquid curable composition for sealing an organic EL element, comprising component (a): polymerizable compound and component (b): polymerization initiator, UV-LED with wavelength of 395nm was used at illuminance of 1500mW/cm ² The cumulative light quantity is 1500mJ/cm ² The cured product of the curable composition obtained by curing has a dielectric constant of 3.6 or less at a frequency of 100kHz, and the hysteresis loss of the sample obtained as the cured product of the curable composition is 0% to 45%.

Description

Curable composition and organic EL display device

Technical Field

The present invention relates to a curable composition and an organic EL display device.

Background

Organic EL elements consume little power, and are therefore being used in displays, lighting devices, and the like. Since organic EL elements are susceptible to deterioration due to moisture and oxygen in the atmosphere, sealing with a sealing material has been studied for use.

Patent document 1 (international publication No. 2015/129670) describes a curable resin composition for sealing an organic electroluminescent display element, which contains a cycloolefin oxide type alicyclic epoxy compound, a phenoxy resin, and a curing agent, and by using such a composition, a cured product excellent in transparency, bending resistance, and barrier property can be obtained.

Prior art literature

Patent literature

Patent document 1: international publication No. 2015/129670

Disclosure of Invention

Problems to be solved by the invention

However, as a result of the study of the technology described in patent document 1, the present inventors have found that there is room for improvement in such a technology in terms of improving durability when the organic EL display device is used for a long period of time.

Means for solving the problems

The present inventors have conducted intensive studies in order to improve durability when an organic EL display device is used for a long period of time. As a result, it has been found that the above-described problems can be solved by using a composition for sealing an organic EL element as a liquid curable composition containing a specific component, and having a composition such that the dielectric constant and hysteresis loss are within specific ranges.

That is, it has been found that a standard such as dielectric constant and hysteresis loss is effective as a design index for improving durability of an organic EL display device in long-term use in a liquid curable composition containing a specific component, and the present invention has been completed.

That is, according to the present invention, there are provided a curable composition and an organic EL display device shown below.

[1] A curable composition which is a liquid curable composition for sealing an organic EL element, comprising: the following components (a) and (b):

(a) The polymerizable compound is used as a monomer for the polymerization reaction,

(b) A polymerization initiator, wherein the polymerization initiator,

with UV-LEDs of wavelength 395nm at illuminance of 1500mW/cm ² The cumulative light quantity is 1500mJ/cm ² The cured product of the curable composition obtained by curing has a dielectric constant of 3.6 or less at a frequency of 100kHz,

the hysteresis loss when measured using the following condition 2 was 0% to 45% for the sample obtained under the following condition 1.

(condition 1) the curable composition was sealed in 2 sheets of glass having a Teflon (registered trademark) sheet of 100 μm thickness sandwiched therebetween, and the UV-LED having a wavelength of 395nm was used to illuminate 1000mW/cm ² The cumulative light quantity is 1500mJ/cm ² The cured product was obtained by curing, and the cured product was cut into a size of 10mm in width by 55mm in length, and the thickness of the cured product was in the range of 90 to 110 μm every 10mm total at 5 positions in the longitudinal direction, and the sample was set.

(condition 2) one end of the sample was fixed, and the other end was fixed so that the distance between chucks became 30 mm. At this time, the state in which no sample was attached was set to 0mN, and in order to eliminate the initial strain, stretching was performed until the load reached 0.05N, and this point was set as the starting point. A tensile test was performed at 23 ℃ and 10 mm/sec (tensile speed) in which the other end was stretched in the 180-degree direction, and in a curve (stress-strain curve) obtained by setting the stress at this time as the vertical axis and the strain as the horizontal axis, the area of the region surrounded by the curve 1 from the start point of the tensile test to 2% of the stretching, the vertical axis, the straight line of "strain=2%" and the horizontal axis was a, the area of the region surrounded by the curve 2 from the 2% of the stretching to the stress of zero, the straight line of "strain=2%" and the area surrounded by the horizontal axis was B, and the solution calculated by { (a-B)/a } ×100 was the hysteresis loss.

[2] The curable composition according to [1], wherein the component (a) contains 1 or more kinds selected from the group consisting of (meth) acrylic compounds having 2 (meth) acryloyl groups in one molecule, epoxy compounds having 2 epoxy groups in one molecule, and oxetane compounds having 2 oxetanyl groups in one molecule.

[3] The curable composition according to [1] or [2], wherein the component (a) contains 2 or more kinds selected from the group consisting of a (meth) acrylic compound having 2 (meth) acryloyl groups in one molecule, an epoxy compound having 2 epoxy groups in one molecule, and an oxetane compound having 2 oxetanyl groups in one molecule.

[4] The curable composition according to any one of [1] to [3], wherein the component (b) is a photo-cationic polymerization initiator.

[5] The curable composition according to any one of [1] to [3], wherein the component (b) is a photo radical polymerization initiator.

[6] The curable composition according to any one of [1] to [5], further comprising component (c): and (3) a leveling agent.

[7] The curable composition according to [6], wherein the component (c) is an acrylic leveling agent.

[8] The curable composition according to any one of [1] to [7], wherein the curable composition has a viscosity of 3 mPas to 50 mPas when measured at 25℃and 20rpm using an E-type viscometer.

[9] The curable composition according to any one of [1] to [8], wherein the component (a) contains 2 or more (meth) acrylic compounds each having 2 (meth) acryloyl groups in one molecule.

[10] An organic EL display device, comprising:

a substrate (substrate),

Organic EL element disposed on the substrate, and method of manufacturing the same

A sealing layer covering the organic EL element,

the sealing layer is composed of a cured product of the curable composition according to any one of [1] to [9 ].

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a technique for improving durability of an organic EL display device in long-term use can be provided.

Drawings

Fig. 1 is a cross-sectional view showing an example of the structure of an organic EL display device according to the embodiment.

Fig. 2 is a diagram schematically showing an example of a stress-strain curve in the embodiment.

Fig. 3 is a plan view for explaining an evaluation method of bending resistance in examples.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description thereof is omitted as appropriate. In the present embodiment, 1 or 2 or more of each component may be used. In the present specification, the term "to" indicating a numerical range includes both a lower limit value and an upper limit value.

(curable composition)

In the present embodiment, the curable composition is a liquid composition for sealing an organic EL element, and includes the following components (a) and (b).

(a) Polymerizable compound

(b) Polymerization initiator

Furthermore, the curable composition was irradiated with illuminance of 1500mW/cm by using a UV-LED having a wavelength of 395nm ² The cumulative light quantity is 1500mJ/cm ² The dielectric constant of the cured product obtained by curing is 3.6 or less at a frequency of 100 kHz.

The hysteresis loss when measured using the following condition 2 was 0% to 45% with respect to the sample obtained using the curable composition under the following condition 1.

(condition 1) the curable composition was sealed in 2 sheets of glass having a Teflon (registered trademark) sheet of 100 μm thickness sandwiched therebetween, and the UV-LED having a wavelength of 395nm was used to illuminate 1000mW/cm ² The cumulative light quantity is 1500mJ/cm ² The cured product was obtained by curing, and the cured product was cut into a size of 10mm in width by 55mm in length, and the cured product having a thickness of 90 to 110 μm at 5 points in total of 10mm in the longitudinal direction was used as a sample.

(condition 2) one end of the sample was fixed and the other end was fixed so that the distance between chucks became 30 mm. At this time, the state where no specimen was attached was set to 0mN, and in order to eliminate the initial strain, stretching was performed until the load reached 0.05N, and this point was set as the starting point. In a tensile test in which the other end is stretched in the 180-degree direction at 23 ℃ at 10 mm/sec (tensile speed), in a curve (stress-strain curve) in which the stress at this time is taken as the vertical axis and the strain is taken as the horizontal axis, the area of the region surrounded by the curve 1 from the start point of the tensile test to 2% of the tensile time, the vertical axis, the straight line of "strain=2%" and the horizontal axis is taken as a, the area of the region surrounded by the curve 2 from 2% of the tensile time to zero of the strain, the straight line of "strain=2%" and the horizontal axis is taken as B, and the solution calculated by { (a-B)/a } ×100 is taken as hysteresis loss.

As described above, the present inventors have found that the criteria such as dielectric constant and hysteresis loss of a cured product of a liquid curable composition containing components (a) and (b) are effective as design indexes for realizing a sealing material capable of improving durability of an organic EL display device in long-term use. Based on the above knowledge, the present inventors have found that by using a curable composition having a dielectric constant of 3.6 or less and a hysteresis loss of 0% or more and 45% or less, a sealing material having improved durability in long-term use can be obtained.

The reason why the durability of the organic EL display device can be improved in long-term use by using such a curable composition is not necessarily clear, but it is considered that the composition is not easily affected by the electric field of the organic EL element and the resin is not easily restored to the original state, and thus strain is easily generated.

The dielectric constant of the cured product of the curable composition is 3.6 or less, for example, 1.0 to 3.6, preferably 1.0 to 3.5, and more preferably 1.0 to 3.3 from the viewpoint of improving the sealing property of the sealing material.

Here, the dielectric constant of the cured product was such that the illuminance was 1500mW/cm for UV-LED having a wavelength of 395nm ² The cumulative light quantity is 1500mJ/cm ² Curing the curable composition under the conditions of (a) and (b)The dielectric constant was measured at a frequency of 100 kHz.

In addition, from the viewpoint of improving the long-term durability of the sealing material, the hysteresis loss of the cured product of the curable composition is 0% or more and 45% or less, preferably 0% or more and 40% or less, more preferably 0% or more and 35% or less, still more preferably 0% or more and 25% or less, still more preferably 0% or more and 20% or less. The hysteresis loss of the cured product of the curable composition may be, for example, 5% or more.

Here, the hysteresis loss of the cured product of the curable composition was obtained by measuring the sample obtained according to the above condition 1 using the curable composition under the above condition 2.

In condition 1, first, the curable composition was sealed in 2 sheets of glass sandwiching a teflon (registered trademark) sheet having a thickness of 100 μm. Then, using a UV-LED with a wavelength of 395nm, the illuminance was 1000mW/cm ² The cumulative light quantity is 1500mJ/cm ² Curing was performed to obtain a cured product having a thickness of approximately 100. Mu.m.

The obtained cured product was cut into a size of 10mm in width by 55mm in length. Among the cut cured products, those having a thickness of 90 to 110 μm at 5 points in total of 10mm in the longitudinal direction were used as samples for measuring hysteresis loss.

The hysteresis loss was measured based on condition 2. For example, a device capable of performing a tensile test such as a universal material tester can be used for the measurement. One end of the sample was fixed to a chuck of the measuring device, and the other end was fixed so that the distance between chucks became 30 mm. A tensile test was performed at 23 ℃ at 10 mm/sec (tensile speed) with the other end stretched in the 180-degree direction to obtain a curve (stress-strain curve) with the stress on the vertical axis and the strain on the horizontal axis. The state where no sample was attached was set to 0mN, and in order to eliminate the initial strain, stretching was performed until the load reached 0.05N, and this point was set as the starting point. That is, at the starting point, the strain was 0mm and the load was 0.05N.

Here, strain refers to ((stretching distance)/(distance between chucks)). The inter-chuck distance represents the inter-chuck distance at the start point, and the stretch distance represents the distance stretched in the 180-degree direction from the start point.

Fig. 2 is a diagram schematically showing an example of a stress-strain curve.

In the stress-strain curve obtained by the tensile test, the area of the region surrounded by the curve 1 from the start point of the tensile test to 2% of the tensile time, the vertical axis, the straight line of "strain=2%" and the horizontal axis is denoted as a, the area of the region surrounded by the curve 2 from 2% of the tensile time to zero of the stress, the straight line of "strain=2%" and the horizontal axis is denoted as B, and the hysteresis loss is calculated by the following equation.

Hysteresis loss = { (a-B)/a } ×100

In the present embodiment, in order to adjust the dielectric constant and hysteresis loss of the cured product of the curable composition to the above-described ranges, for example, the types, the content ratio, the method of producing the curable composition, and the like of the components (a) and (b) need to be highly controlled.

In the present embodiment, examples of factors for controlling the dielectric constant and hysteresis loss of the cured product of the curable composition within the above ranges include:

as the component (a), 1 or more selected from the group consisting of a (meth) acrylic compound having 2 or more (meth) acryloyl groups in one molecule, an epoxy compound having 2 or more epoxy groups in one molecule, and an oxetane compound having 2 or more oxetanyl groups in one molecule;

As component (b), for example, a photo-cationic polymerization initiator is used;

adjusting the mixing ratio of components (a) and (b);

adjusting the viscosity of the curable composition;

heating and stirring materials except the polymerization initiator at a reduced pressure, for example, at a temperature of 40 ℃ or higher, and then adding the polymerization initiator;

when obtaining a cured product of the cured product composition, adjusting the oxygen concentration at the time of film formation (e.g., coating) and curing of the curable composition; etc.

Wherein the mixture is mixed and stirred at a reduced pressure of, for example, 200Pa, for example, 40 ℃ or higher at the time of preparing the cured product composition. When stirring is not performed in a reduced pressure state, oxygen in the gas is dissolved in the liquid, and the oxygen concentration in the liquid becomes high, so that the desired curing property may not be obtained. In addition, when the temperature is too low, oxygen in the liquid is not easily removed, and thus, desirable curing characteristics may not be obtained.

In addition, in the case of coating for film formation, from the viewpoint of improving the reliability of the cured product in long-term use, for example, the coating is performed under an atmosphere having an oxygen concentration of 20.0 to 21.1%, and in the case of curing, for example, in the case of UV curing, the curing is performed at an oxygen concentration of 50ppm to 1000 ppm.

In the present embodiment, the curable composition is preferably a sealant used for coating, and more preferably a sealant used for coating by an inkjet method.

From the viewpoint of improving the ink jet ejectability, the viscosity of the curable composition obtained by measurement at 25℃and 20rpm using an E-type viscometer is preferably 3 mPas or more, more preferably 5 mPas or more, still more preferably 8 mPas or more, and still more preferably 10 mPas or more.

Further, from the viewpoint of improving the ink jet ejectability, the viscosity of the curable composition is preferably 50mpa·s or less, more preferably 30mpa·s or less, further preferably 27mpa·s or less, further more preferably 25mpa·s or less.

Next, the constituent components of the curable composition will be specifically described.

(component (a))

Component (a) is a polymerizable compound. Specific examples of the component (a) include compounds having a radically polymerizable functional group such as a (meth) acryloyl group and a vinyl group (hereinafter, also referred to as "radically polymerizable compounds"); and

a compound having a cationically polymerizable functional group such as an epoxy group, an oxetanyl group, or a vinyl ether group (hereinafter, also referred to as "cationically polymerizable compound").

From the viewpoint of improving durability of the organic EL display device in long-term use, the component (a) preferably contains 1 or more selected from the group consisting of (meth) acrylic compounds having 2 or more (meth) acryloyl groups in one molecule, epoxy compounds having 2 or more epoxy groups in one molecule, and oxetane compounds having 2 or more oxetanyl groups in one molecule; more preferably, the epoxy resin composition contains 1 or more selected from the group consisting of a (meth) acrylic compound having 2 (meth) acryloyl groups in one molecule, an epoxy compound having 2 epoxy groups in one molecule, and an oxetane compound having 2 oxetanyl groups in one molecule; further preferably, the compound contains 2 or more kinds selected from the group consisting of a (meth) acrylic compound having 2 (meth) acryloyl groups in one molecule, an epoxy compound having 2 epoxy groups in one molecule, and an oxetane compound having 2 oxetanyl groups in one molecule, and further preferably, the compound contains 2 or more kinds of (meth) acrylic compounds having 2 (meth) acryloyl groups in one molecule.

In the present embodiment, (meth) acrylic acid means acrylic acid or methacrylic acid.

When the component (a) is a radical polymerizable compound, the radical polymerizable compound is preferably a (meth) acrylic compound.

The (meth) acrylic compound is preferably a (meth) acrylic compound having 2 or more (meth) acryloyl groups in one molecule, and specific examples thereof include a di (meth) acrylic compound and a 3-functional or more (meth) acrylic compound.

Specific examples of the di (meth) acrylic compound include 1 or more selected from the group consisting of aliphatic di (meth) acrylic compounds and alicyclic di (meth) acrylic compounds.

Examples of the aliphatic di (meth) acrylic compound include di (meth) acrylic esters of diols, (poly) alkylene glycol di (meth) acrylic esters, and more specifically, 1, 6-hexanediol diacrylate (for example, A-HD-N, manufactured by Noval chemical industry Co., ltd.), 1, 9-nonanediol diacrylate (for example, A-NOD-N, manufactured by Noval chemical industry Co., ltd.), 1, 10-decanediol diacrylate (for example, A-DOD-N, manufactured by Noval chemical industry Co., ltd.), neopentyl glycol diacrylate (for example, A-NPG, manufactured by Noval chemical industry Co., ltd.), ethylene glycol diacrylate (for example, SR206NS, arkema Co.), polyethylene glycol diacrylate (e.g., A-400, new York chemical industry Co., ltd.), polypropylene glycol diacrylate (e.g., APG-400, new York chemical industry Co., ltd.), tricyclodecane dimethanol diacrylate (e.g., A-DCP), 1, 3-butanediol dimethacrylate (e.g., BG, new York chemical industry Co., ltd.), 1, 4-butanediol dimethacrylate (e.g., BD, new York chemical industry Co., ltd.), 1, 6-hexanediol dimethacrylate (e.g., HD-N, new York chemical industry Co., ltd.), 1, 9-nonanediol dimethacrylate (e.g., NOD-N, new York chemical industry Co., ltd.), and, 1, 10-decanediol dimethacrylate (for example, DOD-N, manufactured by Xinzhou chemical industries, inc.), neopentyl glycol dimethacrylate (for example, NPG, manufactured by Xinzhou chemical industries, inc.).

Examples of the alicyclic di (meth) acrylic compound include dicyclopentyl dimethacrylate (for example, DCP, manufactured by new yo chemical industry).

From the viewpoint of keeping the crosslinking density high, the content of the di (meth) acrylic compound in the (meth) acrylic compound is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, still more preferably 80 parts by mass or more, still more preferably 90 parts by mass or more, based on 100 parts by mass of the entire (meth) acrylic compound. The content of the di (meth) acrylic compound in the (meth) acrylic compound may be, for example, 100 parts by mass or less, or 95 parts by mass or less.

Specific examples of the polyfunctional (meth) acrylic compound having 3 or more functions include 3-functional (meth) acrylic compounds such as trimethylolpropane triacrylate (for example, A-TMPT, manufactured by Xinzu chemical industry Co., ltd.), ethoxylated trimethylolpropane triacrylate (for example, A-TMPT-EO, manufactured by Xinzu chemical industry Co., ltd.), ethoxylated glycerol triacrylate (for example, A-GLY-6E, manufactured by Xinzu chemical industry Co., ltd.), and propoxylated glycerol triacrylate (for example, A-GLY-3P, manufactured by Xinzu chemical industry Co., ltd.);

4-functional (meth) acrylic compounds such as pentaerythritol tetraacrylate (e.g., A-TMMT, manufactured by New Yoghurt chemical industry Co., ltd.), ethoxylated pentaerythritol tetraacrylate (e.g., ATM-4E, manufactured by New Yoghurt chemical industry Co., ltd.), bis (trimethylol) propane tetraacrylate (e.g., AD-TMP-L, manufactured by New Yoghurt chemical industry Co., ltd.);

5-functional aliphatic acrylate compounds such as dipentaerythritol pentaacrylate (for example, M-402, manufactured by east Asia Synthesis Co.); and

dipentaerythritol penta/hexaacrylate (for example, GM66G0H, manufactured by national chemical company) and the like.

On the other hand, examples of the monofunctional (meth) acrylic compound include monofunctional aliphatic (meth) acrylic compounds such as isostearyl acrylate; monofunctional aromatic (meth) acrylic compounds such as benzyl acrylate and ethoxylated ortho-phenylphenol acrylate.

From the viewpoint of improving curability, the (meth) acrylic compound having 2 or more (meth) acryloyl groups in one molecule is preferably a di (meth) acrylate of an aliphatic diol having 8 or more and 12 or less carbon atoms, and more preferably 1 or 2 or more selected from the group consisting of 1, 9-nonanediol diacrylate, 1, 10-decanediol diacrylate, 1, 9-nonanediol dimethacrylate and 1, 10-decanediol dimethacrylate.

From the same viewpoint, the (meth) acrylic compound having 2 or more (meth) acryloyl groups in one molecule preferably contains an aliphatic di (meth) acrylic compound and an alicyclic di (meth) acrylic compound, more preferably contains 1 or 2 or more selected from the group consisting of 1, 9-nonanediol diacrylate, 1, 10-decanediol diacrylate, 1, 9-nonanediol dimethacrylate and 1, 10-decanediol dimethacrylate, and dicyclopentyl dimethacrylate.

The content of the monofunctional acrylate compound in the (meth) acrylic compound is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, still more preferably 12% by mass or less, particularly preferably 8% by mass or less, still more preferably 5% by mass or less, still more preferably 2% by mass or less, relative to the entire (meth) acrylic compound, and the (meth) acrylic compound is particularly preferably free of the monofunctional acrylate compound.

When the component (a) is a cationically polymerizable compound, the component (a) is preferably at least 1 selected from the group consisting of an epoxy compound and an oxetane compound, and more preferably an epoxy compound and an oxetane compound.

The epoxy compound is preferably an epoxy compound having 2 or more epoxy groups in one molecule, and specific examples thereof include a 2-functional epoxy compound and a 3-functional or more epoxy compound.

Specific examples of the 2-functional epoxy compound include a 2-functional alicyclic epoxy compound and a 2-functional aliphatic epoxy compound.

The 2-functional alicyclic epoxy compound is preferably an alicyclic epoxy compound having a cycloolefin oxide structure.

Examples of the alicyclic epoxy compound having a cycloolefin oxide structure include compounds represented by the following general formula (1).

[ chemical 1]

In the general formula (1), X is a single bond or a linking group. The linking group may be, for example, a 2-valent hydrocarbon group, a carbonyl group, an ether group (ether bond), a thioether group (thioether bond), an ester group (ester bond), a carbonate group (carbonate bond), an amide group (amide bond), or a group in which a plurality of them are linked.

Examples of the 2-valent hydrocarbon group in X include an alkylene group having 1 to 18 carbon atoms, a 2-valent alicyclic hydrocarbon group, and the like. Examples of the alkylene group having 1 to 18 carbon atoms include methylene, methyl methylene, dimethyl methylene, ethylene, propylene, trimethylene and the like. Examples of the alicyclic hydrocarbon group having a valence of 2 include a cycloalkyl group having a valence of 2 (including a cycloalkyl group) such as a 1, 2-cyclopentylene group, a 1, 3-cyclopentylene group, a 1, 2-cyclohexylene group, a 1, 3-cyclohexylene group, a 1, 4-cyclohexylene group, and the like.

Among the above, X is preferably a single bond or a linking group having an oxygen atom. The linking group having an oxygen atom is more preferably-CO- (carbonyl) -O-CO-O- (carbonate group) -COO- (ester group), -O- (ether group), -CONH- (amide group) a group in which a plurality of these groups are bonded, or a group in which 1 or more of these groups are bonded to 1 or more of a 2-valent hydrocarbon group. X is more preferably a single bond.

Examples of the epoxy compound represented by the general formula (1) are shown below. In the following formula, l represents an integer of 1 to 10, and m represents an integer of 1 to 30. R represents an alkylene group having 1 to 8 carbon atoms (preferably an alkylene group having 1 to 3 carbon atoms such as a methylene group, an ethylene group, a propylene group, or an isopropylene group).

[ chemical 2]

[ chemical 3]

Examples of the commercially available alicyclic epoxy compound having a cycloolefin oxide structure include Celloxide2021P (3 ',4' -epoxycyclohexylmethyl 3, 4-epoxycyclohexane carboxylate), celloxide2081 (epsilon-caprolactone-modified 3',4' -epoxycyclohexylmethyl 3, 4-epoxycyclohexane carboxylate), celloxide8000, and Celloxide8010 (the above is manufactured by Daicel corporation).

Examples of the 2-functional aliphatic epoxy compound include neopentyl glycol diglycidyl ether (for example, NPG (D), manufactured by four-day synthetic company), 1, 6-hexanediol diglycidyl ether (for example, ED-503, manufactured by ADEKA), propylene glycol diglycidyl ether (for example, SR-PG, manufactured by Osaka pharmaceutical industry Co., ltd.), hydrogenated bisphenol A diglycidyl ether (for example, EX252, manufactured by Nagase ChemteX Co., ltd.), and the like.

Specific examples of the epoxy compound having 3 or more functions include polyfunctional epoxy compounds such as trimethylolpropane polyglycidyl ether (for example, produced by EX-321L,Nagase ChemteX) and diglycerol polyglycidyl ether (for example, produced by EX-421,Nagase ChemteX).

From the viewpoint of improving curability, the epoxy compound having 2 or more epoxy groups in one molecule is preferably 1 or more selected from the group consisting of a compound in which X in the above general formula (1) is a single bond, 3',4' -epoxycyclohexylmethyl 3, 4-epoxycyclohexane carboxylate, and neopentyl glycol diglycidyl ether.

From the viewpoint of improving the initial reaction rate, the content of the epoxy compound in the cationically polymerizable compound is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 25 parts by mass or more, based on 100 parts by mass of the entire cationically polymerizable compound.

In addition, from the viewpoint of improving the elongation reaction rate, the content of the epoxy compound in the cationically polymerizable compound is, for example, 100 parts by mass or less, preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less, based on 100 parts by mass of the entire cationically polymerizable compound.

Next, an oxetane compound will be described.

The oxetane compound is preferably an oxetane compound having 2 or more oxetanyl groups in one molecule, more preferably a 2-functional oxetane compound, and still more preferably a 2-functional oxetane compound represented by the following general formula (6) or (7).

[ chemical 4]

In the general formulae (6) and (7), R ⁵ Independently and separatelyThe alkyl group is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an allyl group, an aryl group, an aralkyl group, a furyl group or a thienyl group, and preferably an alkyl group having 1 to 6 carbon atoms. R is R ⁶ Is a 2-valent organic residue. In the general formula (7), u is a number of 1 to 5, preferably a number of 1 to 3, on the average.

R ⁵ Specifically, examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, and cyclohexyl.

Examples of the aryl group include phenyl, naphthyl, tolyl, and xylyl.

Specific examples of the aralkyl group include benzyl and phenethyl.

In addition, as R ⁶ Specifically, alkylene, polyoxyalkylene, phenylene, xylylene, and structures represented by the following general formula are exemplified.

[ chemical 5]

In the general formula, R ³ Is an oxygen atom, a sulfur atom, -CH ₂ -、-NH-、-SO-、-SO ₂ -、-C(CF ₃ ) ₂ -or-C (CH) ₃ ) ₂ -。

In addition, R ⁴ Is an alkylene group or arylene group having 1 to 6 carbon atoms. Specific examples of the alkylene group having 1 to 6 carbon atoms include methylene, ethylene, propylene, butylene and cyclohexylene.

In addition, R ⁶ The number of carbon atoms of the polyoxyalkylene group is preferably 4 to 30, more preferably 4 to 8. Specific examples of the polyoxyalkylene group include polyoxyethylene and polyoxypropylene.

Specific examples of the compound represented by the general formula (6) include 3-ethyl-3 { [ (3-ethyloxetan-3-yl) methoxy ] methyl } oxetan (for example, OXT-221, manufactured by east Asia Synthesis Co., ltd.). Specific examples of the compound represented by the general formula (7) include 2-functional oxetane compounds such as xylylene dioxetane (for example, OXT121, manufactured by east asia synthesis company, u=1 to 3 in the general formula (7)).

From the viewpoint of improving curability, the oxetane compound having 2 or more oxetanyl groups in one molecule is preferably 3-ethyl-3 { [ (3-ethyloxetan-3-yl) methoxy ] methyl } oxetan.

In addition, the oxetane compound may contain a monofunctional oxetane compound. Examples of the monofunctional oxetane compound include monofunctional aliphatic oxetane compounds such as 3-ethyl-3- [ (2-ethylhexyl oxy) methyl ] oxetane.

From the viewpoint of reducing the dielectric constant of the cured product of the curable composition, the content of the oxetane compound in the cationically polymerizable compound is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, and still more preferably 70 parts by mass or more, based on 100 parts by mass of the entire cationically polymerizable compound.

From the same viewpoint, the content of the oxetane compound in the total cationic polymerizable compound is, for example, 100 parts by mass or less, preferably 95 parts by mass or less, more preferably 90 parts by mass or less, and even more preferably 85 parts by mass or less, based on 100 parts by mass of the total cationic polymerizable compound.

From the viewpoint of improving durability of the organic EL display device in long-term use, the component (a) preferably contains 1 or 2 or more selected from the group consisting of a compound in which X is a single bond in the above general formula (1), neopentyl glycol diglycidyl ether, 3',4' -epoxycyclohexylmethyl 3, 4-epoxycyclohexane carboxylate, 3-ethyl-3 { [ (3-ethyloxetan-3-yl) methoxy ] methyl } oxetane, 1, 9-nonyleneglycol diacrylate, 1, 9-nonyleneglycol dimethacrylate, and trimethylolpropane triacrylate, more preferably contains 1 or 2 or more selected from the group consisting of 3-ethyl-3 { [ (3-ethyloxetan-3-yl) methoxy ] methyl } oxetane, 1, 9-nonyleneglycol diacrylate, and 1, 9-nonyleneglycol dimethacrylate.

Further, the component (a) may contain 1 or 2 or more kinds selected from the group consisting of monofunctional (meth) acrylate compounds, monofunctional epoxy compounds, and monofunctional oxetane compounds. From the viewpoint of improving durability of the sealing material in long-term use, the curable composition preferably contains 1 or 2 or more compounds selected from the group consisting of monofunctional (meth) acrylate compounds and monofunctional oxetane compounds.

The content of the component (a) in the curable composition is preferably 60 to 99.9% by mass, more preferably 80 to 99.9% by mass, further preferably 85 to 99.9% by mass, further more preferably 90 to 98.0% by mass, relative to the total composition of the curable composition, from the viewpoint of improving the strength of the cured product.

(component (b))

Component (b) is a polymerization initiator. Specific examples of the polymerization initiator include 1 or more selected from the group consisting of a thermal radical initiator and a photopolymerization initiator. From the viewpoint of stably forming a cured product at a low temperature, the component (b) contains a polymerization initiator (a photo-radical polymerization initiator such as a UV radical initiator or a photo-cation polymerization initiator such as a UV cation initiator) that generates radicals or ions by irradiation of light such as ultraviolet rays, and is more preferably a photo-cation polymerization initiator.

Specific examples of the photo-cation polymerization initiator include aromatic sulfonium salts and aromatic iodides from the viewpoint of stably forming a cured productSalt, aromatic diazonium->Salts, aromatic ammonium salts, and the like. The anionic part of these salts is, for example, BF ₄ ^- 、(R _f ) _n PF _6-n (R _f Is an organic group, and n is an integer of 1 to 5. ) PF (physical filter) ₆ ^- 、SbF ₆ ^- Or BY ₄ ^- (Y is at least 2The above fluorine or trifluoromethyl substituted phenyl group. ).

Specific examples of the aromatic sulfonium salt include bis [4- (diphenylsulfonium) phenyl ] sulfide bis hexafluorophosphate, bis [4- (diphenylsulfonium) phenyl ] sulfide bis hexafluoroantimonate, bis [4- (diphenylsulfonium) phenyl ] sulfide bis tetrafluoroborate, bis [4- (diphenylsulfonium) phenyl ] sulfide tetrakis (pentafluorophenyl) borate, diphenyl-4- (phenylthio) phenylsulfonium hexafluorophosphate, diphenyl-4- (phenylthio) phenylsulfonium hexafluoroantimonate, and diphenyl-4- (phenylthio) phenylsulfonium tetrafluoroborate.

As aromatic iodineSpecific examples of salts include diphenyliodo->Hexafluorophosphate, diphenyliodo +.>Hexafluoroantimonate, diphenyliodo +.>Tetrafluoroborate, diphenyliodo->Tetrakis (pentafluorophenyl) borate, bis (dodecylphenyl) iodo +.>Hexafluorophosphate, bis (dodecylphenyl) iodo +. >Hexafluoroantimonate, bis (dodecylphenyl) iodo +.>Tetrafluoroborate, bis (dodecylphenyl) iodo +.>Tetrakis (pentafluorophenyl) borate.

As aromatic diazoniumSpecific examples of salts include phenyldiazonium->Hexafluorophosphate, phenyl diazonium->Hexafluoroantimonate, phenyldiazonium->Tetrafluoroborate, phenyl diazonium->Tetrakis (pentafluorophenyl) borate.

Specific examples of the aromatic ammonium salt include 1-benzyl-2-cyanopyridineHexafluorophosphate, 1-benzyl-2-cyanopyridine +.>Hexafluoroantimonate and the like.

Specific examples of commercial products of the photo-cationic polymerization initiator include Irgacure250, irgacure270, irgacure290 (manufactured by BASF corporation, above), CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-310B, CPI-400PG (manufactured by San Apro corporation, above), SP-150, SP-170, SP-171, SP-056, SP-066, SP-130, SP-140, SP-601, SP-606, and SP-701 (manufactured by ADEKA corporation, above). From the viewpoint of stably obtaining a cured film, the photo-cationic polymerization initiator is preferably a sulfonium salt such as Irgacure270, irgacure290, CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-310B, CPI-400PG, SP-150, SP-170, SP-171, SP-056, SP-066, SP-601, SP-606, SP-701 or the like.

Further, specific examples of the photo-radical polymerization initiator include an acyl phosphine oxide photopolymerization initiator such as 2,4, 6-trimethylbenzoyl diphenyl phosphine oxide.

From the viewpoint of improving curability, the content of the component (b) in the curable composition is preferably 0.1 mass% or more, more preferably 0.3 mass% or more, and still more preferably 0.5 mass% or more, relative to the entire composition of the curable composition.

The content of the component (b) in the curable composition is preferably 10 mass% or less, more preferably 6 mass% or less, and even more preferably 4 mass% or less, relative to the total composition of the curable composition, from the viewpoint of suppressing coloration of the curable composition.

The curable composition may contain components other than the components (a) and (b), for example, the curable composition may further contain the component (c): and (3) a leveling agent.

(component (c))

The leveling agent containing the component (c) can improve the flatness of the film formed from the curable composition.

Specific examples of the component (c) include silicone leveling agents such as polyester-modified polydimethylsiloxane (for example, BYK-310, manufactured by BYK japan) and polyether-modified silicone (for example, BYK-345, manufactured by BYK japan);

Acrylic leveling agents such as acrylic copolymers (for example, BYK-350, manufactured by BYK japan; KL700, manufactured by the chemical company of Kyowa Co., ltd.);

fluorine-containing leveling agents such as fluorine-modified polymers (for example, BYK-340, manufactured by BYK japan) and perfluoroalkyl-containing oligomers (for example, surflon S-611 (manufactured by AGC cleaning and beautification Co.).

From the viewpoint of improving the flatness of the curable composition when applied to inkjet printing, the component (c) is preferably 1 or 2 or more selected from the group consisting of acrylic copolymers, polyester-modified polydimethylsiloxanes, and fluorine-modified polymers.

From the same viewpoint, the component (c) is also preferably an acrylic leveling agent.

The content of the component (c) in the curable composition is preferably 0.01 mass% or more, more preferably 0.03 mass% or more, and even more preferably 0.05 mass% or more, relative to the entire composition of the curable composition, from the viewpoint of improving the flatness of the film formed from the curable composition.

The content of the component (c) in the curable composition is preferably 5 mass% or less, more preferably 3 mass% or less, and even more preferably 2 mass% or less, relative to the total composition of the curable composition, from the viewpoint of stabilizing the surface hardness of the cured product.

Examples of other components in the curable composition include coupling agents such as tackifiers, sensitizers, and silane coupling agents.

For example, by including the tackifier in the curable composition, the viscosity of the curable composition can be adjusted without significantly changing the dielectric constant of the cured product of the curable composition, and for example, the viscosity can be desirably increased.

Specific examples of the tackifier include petroleum resins selected from aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, aromatic hydrocarbon resins, and the like; a terpene resin; phenols such as phenol resins; and 1 or 2 or more kinds of rosin resins.

Examples of the petroleum resin include C5 monomers obtained from pentene, pentadiene, isoprene, etc., or oligomers thereof;

c9 monomers obtained from indene, methylindene, vinyl toluene, styrene, α -methylstyrene, β -methylstyrene, etc., or oligomers thereof;

copolymers of C5 monomers and C9 monomers (C5-C9 copolymer resins);

alicyclic monomers or polymers thereof obtained from cyclopentadiene, dicyclopentadiene, or the like;

aromatic monomers such as isopropenyl toluene, and polymers thereof;

hydrides of the above-mentioned various monomers or polymers thereof;

Modified petroleum resins obtained by modifying the above-mentioned various monomers or polymers thereof with maleic anhydride, maleic acid, fumaric acid, (meth) acrylic acid, phenol, or the like.

The petroleum resin used as the tackifier is preferably a styrene-based oligomer from the viewpoint of excellent compatibility with the component (a). From the same viewpoint, the component (a) is preferably a petroleum resin produced using dicyclopentadiene as a main raw material, and more preferably a petroleum resin having an ester group in the molecule (for example, QTN, manufactured by japan rayleigh company).

Examples of the terpene resin include aromatic modified terpene resins obtained by copolymerizing terpenes such as α -pinene resin, β -pinene resin, α -pinene monomer, β -pinene monomer and an aromatic monomer such as styrene.

Specific examples of phenols include phenol compounds such as phenol, m-cresol, 3, 5-xylenol, p-alkylphenol, and resorcinol.

Specific examples of the phenol resin include resol resins obtained by adding formaldehyde to these phenol compounds with an alkaline catalyst, and novolak resins obtained by condensing them with an acid catalyst. Further, the phenolic resin includes a rosin phenolic resin obtained by adding phenol to rosin using an acid catalyst and performing thermal polymerization.

Examples of the rosin resin include gum rosin, wood rosin, and tall oil rosin, stabilized rosin obtained by disproportionation or hydrogenation treatment of these rosins, polymerized rosin, modified rosin obtained by modifying these rosins with maleic anhydride, maleic acid, fumaric acid, (meth) acrylic acid, phenol, and the like, and esterified products thereof. The alcohol used for obtaining the esterified product is preferably a polyol. Examples of the polyhydric alcohol include dihydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, and neopentyl glycol; triols such as glycerin, trimethylolethane, trimethylolpropane, etc.; tetraols such as pentaerythritol and diglycerol; dipentaerythritol and the like.

The content of the tackifier in the curable composition is preferably 1 mass% or more, more preferably 3 mass% or more, further preferably 5 mass% or more, and further preferably 30 mass% or less, more preferably 25 mass% or less, further preferably 20 mass% or less, relative to the total composition of the curable composition, from the viewpoint of making the viscosity of the curable composition a preferable viscosity.

The curability of the curable composition can be further improved by including a sensitizer in the curable composition. Examples of the sensitizer include a photo-cation sensitizer.

Specific examples of the sensitizer include thioxanthone compounds such as 2, 4-diethylthioxanthone, 2-dimethoxy-1, 2-diphenylethane-1-one, benzophenone, 2, 4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4 '-bis (dimethylamino) benzophenone, 4-benzoyl-4' -methylbenzophenone sulfide, and 9, 10-dibutoxyanthracene.

The content of the sensitizer in the curable composition is preferably 0.01 mass% or more, more preferably 0.03 mass% or more, and even more preferably 0.05 mass% or more, relative to the total composition of the curable composition, from the viewpoint of improving curability of the curable composition.

The content of the sensitizer in the curable composition is preferably 20 mass% or less, more preferably 10 mass% or less, further preferably 5 mass% or less, further more preferably 1 mass% or less, from the viewpoint of making the visible light transmittance of the cured product preferable.

Next, a method for producing the curable composition will be described.

In the present embodiment, the method for producing a curable composition includes, for example, a step of mixing the components (a) and (b) with other components to obtain a liquid curable composition. Further, the obtained curable composition can be cured to obtain a cured product.

In this case, as described above, the types, the content ratio, the method for producing the curable composition, and the like of the components (a) and (b) are controlled to a high degree, whereby the dielectric constant and hysteresis loss of the cured product of the curable composition can be stably adjusted within the above-described ranges. For example, the curable composition can be obtained by mixing the above components using, for example, a mixer such as a homogenizing and dispersing machine, a homogenizing mixer, a universal mixer, a planetary mixer, a kneader, or a three-roll mixer. In addition, from the viewpoint of stably mixing the curable composition, it is more preferable to mix the component (b) after mixing the components other than the component (b). In addition, it is preferable to adjust the degree of reduced pressure and the mixing temperature when the raw materials of the curable composition are mixed and stirred, and the oxygen concentration when the cured product is obtained. By such a method, the liquid can be uniformly adjusted, and a cured product free from unevenness can be obtained, and the dielectric constant and hysteresis loss of the cured product of the curable composition can be easily controlled within the above-described ranges.

The curable composition obtained in this embodiment is suitable for use in, for example, sealing of a display device, and preferably sealing of an organic EL display device.

The cured product of the curable composition obtained in this embodiment is used as a sealing material for, for example, a display device, preferably an organic EL display device, whereby a display device excellent in durability in long-term use can be obtained.

Hereinafter, an organic EL display device will be described as an example of a structure of the display device.

(organic EL display device)

In this embodiment, the organic EL display device has a layer composed of a cured product of the curable composition.

Fig. 1 is a cross-sectional view showing an example of the structure of an organic EL display device according to this embodiment. The display device 100 shown in fig. 1 is an organic EL display device, and includes: a substrate (base layer 50), an organic EL element (light-emitting element 10) disposed on the base layer 50, and a sealing layer 22 (which may be a cover layer 22 or a barrier layer 22) covering the light-emitting element 10. For example, the sealing layer 22 is made of a cured product of the curable composition of the present embodiment.

In fig. 1, the display device 100 includes, as layers located closer to the observation side than the light-emitting element 10, a barrier layer 21 (which may be the touch panel layer 21 or the surface protective layer 21), a sealing layer 22 (which may be the cover layer 22 or the barrier layer 22), a planarizing layer 23 (which may be the sealing layer 23), and a barrier layer 24. The planarization layer 23 is provided on the base layer 50 so as to cover the light-emitting element 10, and the barrier layer 24 is provided on the surface of the planarization layer 23. The sealing layer 22 is provided on the base material layer 50 so as to cover the planarizing layer 23 and the barrier layer 24. Further, a barrier layer 21 is provided on the sealing layer 22.

The specific configuration of each layer is not limited, and appropriate configurations can be adopted based on generally known information. Such a display device 100 can be manufactured based on generally known information.

Examples

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited thereto.

First, materials used in the following examples are shown.

((a) polymerizable Compound)

Polymerizable compound 1: 2-functional alicyclic epoxy compound, celloxide CEL8010 (a compound (presumption) represented by the following formula, manufactured by Daicel Co., ltd.)

[ chemical 6]

Polymerizable compound 2: 2-functional aliphatic epoxy compound, NPG (D), neopentyl glycol diglycidyl ether, manufactured by Sieve Synthesis Co., ltd

Polymerizable compound 3: 2-functional aliphatic oxetane compound, OXT221, manufactured by east Asia Synthesis Co., ltd., 3-ethyl-3 { [ (3-ethyloxetan-3-yl) methoxy ] methyl } oxetan

Polymerizable compound 4: 2-functional alicyclic methacrylate Compound, DCP, dicyclopentyl dimethacrylate manufactured by Xinzhongcun chemical industry Co., ltd

Polymerizable compound 5: 2-functional aliphatic methacrylate compound, NOD-N, 1, 9-nonanediol dimethacrylate from Xinzhongcun chemical industry Co

Polymerizable compound 6: 2-functional aliphatic acrylate compound, A-NOD-N, 1, 9-nonanediol diacrylate manufactured by Xinzhongcun chemical industry Co

Polymerizable compound 7: monofunctional aliphatic acrylate Compound, isostearyl acrylate manufactured by Xinzhongcun chemical Co., ltd

Polymerizable compound 8: 3-functional aliphatic acrylate compound, A-TMPT, manufactured by Xinzhongcun chemical industry Co., ltd., trimethylolpropane triacrylate

Polymerizable compound 9: 5-functional aliphatic acrylate compound, M-402, manufactured by east Asia Synthesis Co., ltd., dipentaerythritol pentaacrylate

Polymerizable compound 10: monofunctional aliphatic oxetane Compound, OXT212, 3-ethyl-3- [ (2-ethylhexyl oxy) methyl ] oxetane manufactured by east Asia Synthesis Co., ltd

Polymerizable compound 11: monofunctional aromatic acrylate compound, A-LEN-10, manufactured by Xinzhongcun chemical industry Co., ltd., ethoxylated ortho-phenylphenol acrylate

Polymerizable compound 12: monofunctional aromatic acrylate Compound, VISCOAT 160, manufactured by Osaka organic chemical industry Co., ltd., benzyl acrylate

((b) polymerization initiator)

Polymerization initiator 1: photo cation initiator, CPI210S, manufactured by San Apro Co

Polymerization initiator 2: photo radical initiator, TPO, 2,4, 6-trimethylbenzoyl-diphenylphosphine oxide manufactured by BASF Co

((c) leveling agent)

Leveling agent 1: acrylic copolymer, KL700, manufactured by Kyowa chemical Co., ltd

(other Components)

Other ingredient 1 (tackifier): homopolymers of styrene-based oligomers (isopropenyl toluene (IPT) (styrene-based oligomers, weight average molecular weight: 1200, number average molecular weight: 800))

Other ingredients 2 (photo cation sensitizer): 9, 10-dibutoxyanthracene, UVS-1331, manufactured by Kawasaki chemical industry Co., ltd

Examples 1 to 8 and comparative examples 1 to 3

The components were blended on a total 11kg scale so as to have the blending compositions shown in table 1, and a liquid curable composition was obtained. At this time, all the components other than the polymerization initiator are mixed, the inside of the system is depressurized by a vacuum pump, mixed and stirred at 80℃for 4 hours under an atmosphere having a depressurization degree of 190Pa to 210Pa, and then, after the temperature is lowered to room temperature, the mixture is transferred to a tank in which the polymerization initiator is added by performing nitrogen extrusion, and mixed and stirred at 40℃for 1 hour under an atmosphere having a depressurization degree of 190Pa to 210Pa, in order to prevent the mixing of oxygen. In addition, when the film is applied, the film is cured in an atmosphere having an oxygen concentration of 20.0 to 21.1% and when UV-cured, the film is cured at an oxygen concentration of 50ppm to 1000 ppm.

Physical properties of the curable compositions or cured products thereof obtained in each example were measured by the following methods. The measurement results are summarized in Table 1.

(viscosity of curable composition)

The viscosities of the curable compositions obtained in each example were measured using an E-type viscometer (LV-DV-II+, manufactured by BROOKFIELD Co., ltd.) at 25℃and 20 rpm.

The evaluation criteria for the viscosity shown in table 1 are as follows.

A:3 mPas to 50 mPas inclusive

B: less than 3 mPas or more than 50 mPas

(hysteresis loss of cured product of curable composition)

According to the above method, a cured product of the curable composition was produced, and hysteresis loss was obtained from the tensile test result of the cured product.

That is, first, the curable composition was sealed in 2 sheets of glass having a Teflon (registered trademark) sheet (MSF-100, manufactured by Zhonghua chemical industry Co., ltd.) sandwiched therebetween and having a thickness of 100. Mu.m. Furthermore, the UV-LED with wavelength of 395nm was used at illuminance of 1000mW/cm ² The cumulative light quantity is 1500mJ/cm ² Curing was performed to obtain a cured product having a thickness of about 100. Mu.m.

One end of the sample was fixed to a chuck, and a tensile test was performed at 23℃and 10 mm/sec (tensile speed) using a universal material tester AG-X-Plus, shimadzu corporation, to draw the other end in a direction of 180 degrees, whereby a curve (stress-strain curve) was obtained in which stress was on the vertical axis and strain was on the horizontal axis. The state where no sample was attached was set to 0mN, and in order to eliminate the initial strain, stretching was performed until the load reached 0.05N, and this point was set as the starting point. Therefore, at the starting point, the strain was 0mm and the load was 0.05N. In the stress-strain curve, the area of the region surrounded by the curve 1 from the start point of the tensile test to 2% of the tensile time, the vertical axis, the straight line of "strain=2%" and the horizontal axis is denoted as a, the area of the region surrounded by the curve 2 from 2% of the tensile time to zero of the stress, the straight line of "strain=2%" and the horizontal axis is denoted as B, and the hysteresis loss is calculated by the following equation.

Hysteresis loss = { (a-B)/a } ×100

The evaluation criteria for hysteresis loss shown in table 1 are as follows.

A:0% to 45%

B: more than 45%

(dielectric constant of cured product of curable composition)

A coating film for obtaining a cured product for measuring the dielectric constant was prepared by the following method. That is, the obtained curable composition was introduced into an inkjet cartridge DMC-11610 (manufactured by Fuji photo Dimatix Co.). The ink jet cartridge was set in an ink jet device DMP-2831 (manufactured by Fuji photo Dimatix Co., ltd.) and after adjustment of the discharge state, a substrate having aluminum deposited on an alkali-free glass at a thickness of 100nm was coated with a film having a thickness of 5cm×5cm so that the thickness after curing became 10. Mu.m. At this time, the reaction was performed at an oxygen concentration of 20.6%.

After the obtained coating film was left at room temperature (25 ℃) for 1 minute, it was irradiated with an illuminance of 1500mW/cm by means of a UV-LED having a wavelength of 395nm ² The cumulative light quantity is 1500mJ/cm ² Curing the cured product at an oxygen concentration of 1000ppm or less.

Then, aluminum was deposited on the ink-jet coated surface at a thickness of 100nm, and the dielectric constant was measured by an automatic balance bridging method using an LCR meter HP4284A (manufactured by Agilent Technologies Co.) at a condition of 100 kHz.

The evaluation criteria for the dielectric constants shown in table 1 are as follows.

A:3.6 or less

B: exceeding 3.6

Further, regarding the curable compositions obtained from the respective examples, as an index of long-term durability when used for a sealing material of a display device, bending resistance and EL element damage were evaluated. The evaluation method is as follows. The evaluation results are summarized in table 1.

(evaluation method)

(bending resistance)

As an index of the bending resistance, the following method was used to evaluate the haze after 30 ten thousand times of the folding endurance test.

The curable compositions obtained in each example were introduced into inkjet cartridges DMC-11610 (manufactured by Fuji photo Dimatix Co.). The ink jet cartridge was set in an ink jet device DMP-2831 (manufactured by Fuji photo Dimatix Co., ltd.) and after adjustment of the discharge state, it was coated on a PET film (25 μm, A31) of 6 cm. Times.6 cm in such a manner that the thickness after curing became 10. Mu.m, and was 5 cm. Times.5 cm in size. At this time, the oxygen concentration is in the range of 20.0% to 21.1%. After the obtained coating film was left at room temperature (25 ℃) for 1 minute, it was irradiated with 1000mW/cm using a UV-LED having a wavelength of 395nm ² The cumulative light quantity is 1500mJ/cm ² Curing the cured product at an oxygen concentration of 1000ppm or less.

The obtained cured product was used as a measurement sample, and the bending resistance was evaluated. Fig. 3 is a plan view for explaining an evaluation method of bending resistance. The measurement sample (sample 31 in fig. 3, which was disposed so that the PET film was a lower surface and the cured film was an upper surface) was fixed to the sample fixing plate 33 by a double-sided tape 35 (Nicetack NW-15, manufactured by nichiba corporation) with a bending radius set to 1mm as shown in fig. 3, and bending was performed 30 ten thousand times at a bending speed of 30 times within 1 minute. After 1000 times of bending, the appearance was visually confirmed within 10 minutes, and the presence or absence of cloudiness was evaluated. After 30 ten thousand bends were completed, the appearance was visually confirmed within 10 minutes, and the presence or absence of cloudiness was evaluated. The case where no cloudiness was observed after the 1000 times of bending was completed (hereinafter, a and B) was regarded as acceptable.

The evaluation criteria are shown below.

A: without white turbidity

B: there was no cloudiness after 1000 bends, but there was cloudiness after 30 ten thousand bends

C: after 1000 times of bending, there is white turbidity

(damage to EL element)

As an index of EL element damage, reliability of the organic EL display element was evaluated by the following method.

For a glass substrate on which an ITO electrode was formed, the substrate was treated with a UV-ozone treatment apparatus (manufactured by SEN special light source Co., ltd., PL21-200 (S)/UVE-200J), then each was subjected to ultrasonic washing with an alkaline aqueous solution, pure water, acetone and isopropyl alcohol for 15 minutes, and finally, ultrasonic washing with acetone for 10 minutes was performed.

Next, the substrate was fixed to a substrate stage of a vacuum vapor deposition apparatus, and bipyrazino [2,3-f:2',3' -h was added to element Tao Ganguo]Quinoxaline-2, 3,6,7,10, 11-hexacarbonitrile (HAT-CN) 200mg, 9-phenyl-3, 6-bis (9-phenyl-9H-carbazol-3-yl) -9H-carbazole (Tris-PCz) 200mg was added to another element Tao Ganguo, and the vacuum chamber was depressurized to 1X 10 ^-4 Pa. Then, the crucible containing HAT-CN is heated to make HAT-CN vapor deposited at a vapor deposition rateDeposited on a substrate, and formed into a film having a thickness of 100nm. Next, the crucible containing Tris-PCz was heated to a vapor deposition rate +.>The film was deposited on a substrate to form a film having a thickness of 400nm. Next, the process is carried out200mg of tris (8-hydroxyquinoline) aluminum (Alq 3) was added to another substance Tao Ganguo, and the vacuum chamber was again depressurized to 1X 10 ^-4 Pa. Next, the crucible containing Alq3 (tris (8-quinolinolato) aluminum) is heated to a vapor deposition rate +. >The film is thick film 700nm. Then, 200mg of lithium fluoride was added to a tungsten-made resistance-heated boat (boat), and the vacuum chamber was depressurized to 1X 10 ^-4 Pa, lithium fluoride in->The deposition rate of (2) was 5nm. Finally, 1g of magnesium and 200mg of silver were added to a tungsten-made resistance-heated boat, and the vacuum chamber was depressurized to 1X 10 ^-4 Pa, magnesium in->Silver->Is formed into a film at 150nm so that the ratio of magnesium/silver=1/9. The inside of the evaporator was returned to normal pressure by nitrogen gas, and a substrate having a laminate of 8mm×8mm and an organic light-emitting material layer was taken out.

The laminate having the organic light-emitting material layer was subjected to dropwise addition of 30mg of the curable composition obtained in each example as a sealing material under a nitrogen atmosphere, covered with glass, and irradiated with light of 395nm at 400mW for 4 seconds by a UV irradiation device to cure the sealing material.

After the obtained organic EL display element was exposed to an environment at a temperature of 85 ℃ for 96 hours, a voltage of 3V was applied, and the light-emitting state of the organic EL display element was visually confirmed.

The evaluation criteria are shown below. The following A and B were qualified.

A: the element emits light without a dark spot.

B: dark spots exist locally when the element emits light.

C: dark spots exist on the whole surface when the element emits light, and shrinkage of the light emitting region is also observed.

TABLE 1

As is clear from table 1, in the curable compositions obtained in the examples, the dielectric constant of the cured product was 3.6 or less, and the hysteresis loss was in the range of 0% to 45%. Further, by using the curable composition of each example for sealing a display device, a display device excellent in durability in long-term use can be obtained.

The present application claims priority based on japanese patent application No. 2021-076201 filed on 28 of 4 of 2021, and the entire disclosure thereof is incorporated herein.

Symbol description

10 light emitting element

21 Barrier layer, touch Panel layer or surface protective layer

22 sealing, covering or barrier layers

23. Planarization or sealing layers

24. Barrier layer

31. Sample of

33. Sample fixing plate

35. Double-sided adhesive tape

50. Substrate layer

100. A display device.

Claims

1. A curable composition which is a liquid curable composition for sealing an organic EL element, comprising: the following components (a) and (b):

(b) A polymerization initiator, wherein the polymerization initiator,

The hysteresis loss of the sample obtained under the following condition 1 was 0% to 45% when measured under the following condition 2,

condition 1: the curable composition was sealed in 2 glass sheets having a thickness of 100 μm and a registered trademark of Teflon, and the UV-LED having a wavelength of 395nm was used to obtain an illuminance of 1000mW/cm ² The cumulative light quantity is 1500mJ/cm ² Curing to obtain a cured product, cutting the cured product into a size of 10mm in width by 55mm in length, and setting the cured product having a thickness of 90 to 110 μm at 5 points in total of 10mm in the longitudinal direction as the sample,

condition 2: one end of the sample was fixed such that the distance between chucks was 30mm, the other end was fixed, at this time, the state where no sample was attached was set to 0mN, in order to eliminate the initial strain, stretching was performed until the load reached 0.05N, the point was set as a starting point, a stretching test was performed in which the other end was stretched in the 180-degree direction at a stretching speed of 10 mm/sec at 23 ℃, in a stress-strain curve obtained by setting the stress at this time as the vertical axis, the strain was set as the horizontal axis, the area of the region surrounded by the curve 1 from the starting point to 2% stretching in the stretching test, the area of the straight line from the starting point to the vertical axis, "strain=2%" and the horizontal axis was set as a, the area of the straight line from the 2% stretching to the stress at zero, "strain=2%" and the area surrounded by the horizontal axis were set as B, and the solution obtained by { (a-B)/a } ×100 was set as the hysteresis loss.

2. The curable composition according to claim 1, wherein the component (a) contains 1 or more selected from the group consisting of a (meth) acrylic compound having 2 (meth) acryloyl groups in one molecule, an epoxy compound having 2 epoxy groups in one molecule, and an oxetane compound having 2 oxetanyl groups in one molecule.

3. The curable composition according to claim 1 or 2, wherein the component (a) contains 2 or more kinds selected from the group consisting of a (meth) acrylic compound having 2 (meth) acryloyl groups in one molecule, an epoxy compound having 2 epoxy groups in one molecule, and an oxetane compound having 2 oxetanyl groups in one molecule.

4. The curable composition according to any one of claims 1 to 3, wherein the component (b) is a photo-cationic polymerization initiator.

5. The curable composition according to any one of claims 1 to 3, wherein the component (b) is a photo radical polymerization initiator.

6. The curable composition according to any one of claims 1 to 5, further comprising component (c): and (3) a leveling agent.

7. The curable composition according to claim 6, wherein the component (c) is an acrylic leveling agent.

8. The curable composition according to any one of claims 1 to 7, wherein the curable composition has a viscosity of 3 to 50 mPas when measured at 25 ℃ and 20rpm using an E-type viscometer.

9. The curable composition according to any one of claims 1 to 8, wherein the component (a) comprises 2 or more (meth) acrylic compounds having 2 (meth) acryloyl groups in one molecule.

10. An organic EL display device, comprising:

a substrate (substrate),

An organic EL element disposed on the substrate, and

a sealing layer covering the organic EL element,

the sealing layer is composed of a cured product of the curable composition according to any one of claims 1 to 9.