TW201728663A - Sealant for organic electroluminescent display element - Google Patents

Abstract

The objective of the present invention is to provide a sealant for an organic electroluminescent display element capable of suppressing the occurrence of outgassing, and having superior storage stability and coating properties. The present invention is a sealant for an organic electroluminescent display element and contains a cationically polymerizable compound and a thermal cationic polymerization initiator, wherein the cationically polymerizable compound contains a compound represented by formula (1-1) and a compound represented by formula (1-2) and the thermal cationic polymerization initiator is a quarternary ammonium salt for which the counter anion is borate-based.

Description

Sealant for organic electroluminescent display elements

The present invention relates to a sealant for an organic electroluminescence display element which is capable of suppressing generation of outgas and having excellent storage stability and coating properties.

In recent years, the industry is advancing research into organic optical devices using organic thin film elements such as organic electroluminescence (hereinafter referred to as "organic EL") display elements or organic thin film solar cell elements. Since the organic thin film element can be easily produced by vacuum vapor deposition or solution coating, it is excellent in productivity.

The organic EL display element has a film structure in which an organic light-emitting material layer is sandwiched between a pair of electrodes facing each other. Self-luminescence is performed by injecting electrons from the one electrode into the organic light-emitting material layer and injecting holes from the other electrode to bond the electrons and the holes in the organic light-emitting material layer. Compared with a liquid crystal display element or the like that requires a backlight, it is excellent in visibility, can be further reduced in thickness, and can be driven at a DC low voltage.

However, such an organic EL display element has a problem that if the organic light-emitting material layer or the electrode is exposed to the outside atmosphere, its light-emitting characteristics are rapidly deteriorated, resulting in a shortened life. Therefore, in order to improve the stability and durability of the organic EL display element, it is indispensable for the organic EL display element to seal the organic light-emitting material layer or the electrode from moisture or oxygen in the atmosphere.

Patent Document 1 discloses a method in which an organic EL display element substrate is filled with a photocurable adhesive between the organic EL display element substrates, and the light is irradiated and sealed. However, such conventional photocurable adhesives have a problem of causing outgassing upon light irradiation to deteriorate the element, or a problem of poor storage stability or coatability.

Prior technical literature

Patent literature

Patent Document 1: Japanese Laid-Open Patent Publication No. 2001-357973

An object of the present invention is to provide a sealing agent for an organic electroluminescence display element which is capable of suppressing generation of outgas and having excellent storage stability and coating properties.

The present invention relates to a sealant for an organic electroluminescence display device, comprising a cationically polymerizable compound and a thermal cationic polymerization initiator, and the cationically polymerizable compound contains a compound represented by the following formula (1-1) and the following formula The compound represented by (1-2), wherein the above-mentioned thermal cationic polymerization initiator is a counter-anions which is a quaternary ammonium salt of a borate system.

Hereinafter, the present invention will be described in detail.

The inventors of the present invention have studied the use of a thermosetting composition in place of the photocurable composition disclosed in Patent Document 1 as a sealing agent for an organic EL display device. However, such a thermosetting composition is also difficult to suppress the effect of suppressing outgassing, the storage stability, and the coating property. Therefore, the inventors of the present invention conducted further efforts and found that by using a specific two kinds of cationically polymerizable compounds in combination and using a specific thermal cationic polymerization initiator, generation of suppressed outgassing and storage stability can be obtained. The present invention has been completed by a sealant for an organic EL display device having excellent coatability.

The sealing agent for an organic EL display device of the present invention contains a cationically polymerizable compound. The cationically polymerizable compound contains the compound represented by the above formula (1-1) and the compound represented by the above formula (1-2). The organic compound of the present invention is obtained by containing the compound represented by the above formula (1-1) and the compound represented by the above formula (1-2), and further containing a quaternary ammonium salt having a counter anion as a borate salt as a thermal cationic polymerization initiator. The sealant for EL display elements is excellent in storage stability and coating property because it suppresses generation of outgas.

a compound represented by the above formula (1-1) and a compound represented by the above formula (1-2) The content ratio is preferably a compound represented by the above formula (1-1): a compound represented by the above formula (1-2) = 9:1 to 1:4. When the content ratio of the compound represented by the above formula (1-1) to the compound represented by the above formula (1-2) is in this range, the effect of suppressing outgassing, storage stability, and coatability are more excellent. By. The content ratio of the compound represented by the above formula (1-1) to the compound represented by the above formula (1-2) is more preferably a compound represented by the above formula (1-1): the above formula (1-2) The compound represented = 7:1~1:2.

The commercially available ones of the compounds represented by the above formula (1-1) include Celloxide 8000 (manufactured by Daicel Co., Ltd.), and those of the compounds represented by the above formula (1-2) include Celloxide 2021P (Daicel). Made by the company).

The sealing agent for an organic EL display device of the present invention may contain, as a cationically polymerizable compound, another cationically polymerizable compound such as a bisphenol A epoxy resin or a bisphenol F epoxy resin, within a range not inhibiting the object of the present invention. However, from the viewpoint of achieving both the coatability and the effect of suppressing the outgassing, it is preferred that the other cationically polymerizable compound is not contained.

In the case of containing the above-mentioned other cationically polymerizable compound, the compound represented by the above formula (1-1) and the above formula (100 parts by weight of the entire cationically polymerizable compound) in terms of coating properties and suppression of outgassing A preferred lower limit of the total content of the compounds represented by 1-2) is 60 parts by weight. A more preferred lower limit of the total content of the compound represented by the above formula (1-1) and the compound represented by the above formula (1-2) is 70 parts by weight, and a still more preferred lower limit is 80 parts by weight.

The sealant for an organic EL display device of the present invention contains a thermal cationic polymerization initiator. The thermal cationic polymerization initiator is a quaternary ammonium salt of a borate system (hereinafter also referred to as "borate quaternary ammonium salt"). The counter anion of the above-mentioned borate-based quaternary ammonium salt is preferably BF ₄ ^- or (BX ₄ ) ^- (wherein X represents a phenyl group substituted with at least two or more fluorine or trifluoromethyl groups).

Specific examples of the borate-based quaternary ammonium salt include dimethylphenyl (4-methoxybenzyl) ammonium tetrakis(pentafluorophenyl) borate and dimethylphenyl (4). -methylbenzyl)ammonium hexafluorotetrakis(pentafluorophenyl)borate, methylphenyldibenzylammonium tetrakis(pentafluorophenyl)borate, phenyltribenzylammonium tetrakis(pentafluorophenyl) Borate, dimethylphenyl (3,4-dimethylbenzyl) ammonium tetrakis(pentafluorophenyl)borate, N,N-diethyl-N-benzylphenylammonium tetrafluoride, and the like. Among them, dimethylphenyl(4-methoxybenzyl)ammonium tetrakis(pentafluorophenyl)borate is preferred from the viewpoint of achieving both storage stability and hardenability.

The commercially available one of the borate-based quaternary ammonium salts is, for example, CXC-1821 (manufactured by King Industries Co., Ltd.).

The content of the borate-based quaternary ammonium salt is preferably 0.05 parts by weight, and preferably 10 parts by weight, based on 100 parts by weight of the cationically polymerizable compound. When the content of the above-mentioned borate-based quaternary ammonium salt is in this range, the obtained sealant for an organic EL display device is more excellent in curability, storage stability, and moisture resistance of a cured product. A more preferred lower limit of the content of the above-mentioned borate-based quaternary ammonium salt is 0.1 part by weight, and a more preferred upper limit is 5 parts by weight.

The sealant for an organic EL display device of the present invention preferably contains a stabilizer. The sealant for an organic EL display device of the present invention is more excellent in storage stability by containing the above stabilizer.

Examples of the stabilizer include an amine compound such as benzylamine or an aminophenol-based epoxy resin.

The content of the stabilizer is preferably 0.001 part by weight, and preferably the upper limit is 2 parts by weight, based on 100 parts by weight of the cationically polymerizable compound. When the content of the stabilizer is within this range, the obtained sealant for an organic EL display element is excellent in maintenance In the case of hardening, the storage stability is more excellent. A more preferred lower limit of the content of the above stabilizer is 0.005 part by weight, and a more preferred upper limit is 1 part by weight.

In order to improve the adhesion between the sealing agent for an organic EL display device of the present invention and a substrate, the sealing agent for an organic EL display device of the present invention may further contain a decane coupling agent, but it is preferable from the viewpoint of suppressing generation of outgas. It does not contain a decane coupling agent.

Examples of the above decane coupling agent include 3-aminopropyltrimethoxydecane, 3-mercaptopropyltrimethoxydecane, 3-glycidoxypropyltrimethoxydecane, and 3-isocyanatepropylpropane. Trimethoxy decane and the like. These decane coupling agents may be used singly or in combination of two or more.

In the case of containing the above decane coupling agent, the content of the above decane coupling agent is preferably 0.5 part by weight based on 100 parts by weight of the cationically polymerizable compound. By setting the content of the above decane coupling agent to 0.5 part by weight or less, generation of outgassing or bleed out of the remaining decane coupling agent can be suppressed and a higher adhesion improving effect can be exhibited. A more preferable upper limit of the content of the above decane coupling agent is 0.1 part by weight.

The sealant for an organic EL display device of the present invention may further contain a heat hardener within a range not inhibiting the object of the present invention.

Examples of the above-mentioned thermosetting agent include an anthracene compound, an imidazole derivative, an acid anhydride, a dicyandiamide, an anthracene derivative, a modified aliphatic polyamine, and an addition product of various amines and an epoxy resin.

The ruthenium compound may, for example, be 1,3-bis(decylcarbonylethyl)-5-isopropylhydantoin or the like.

Examples of the imidazole derivative include 1-cyanoethyl-2-phenylimidazole, N-(2-(2-methyl-1-imidazolyl)ethyl)urea, and 2,4-diamine. -6-(2'-methylimidazolyl-(1'))-ethyl-symmetric three , N,N'-bis(2-methyl-1-imidazolylethyl)urea, N,N'-(2-methyl-1-imidazolylethyl)hexanediamine, 2-phenyl- 4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and the like.

Examples of the acid anhydride include tetrahydrophthalic anhydride and ethylene glycol bis(hydrogen trimellitate).

These thermosetting agents may be used singly or in combination of two or more.

The sealant for an organic EL display device of the present invention may further contain a surface modifier insofar as it does not inhibit the object of the present invention. By including the surface modifying agent, the flatness of the coating film of the sealing agent for an organic EL display device of the present invention can be improved.

Examples of the surface modifier include a surfactant, a leveling agent, and the like.

Examples of the surface modifier include surface modifiers such as polyfluorene, acrylic, and fluorine.

For example, BYK-302, BYK-331 (all manufactured by BYK-Chemie Japan Co., Ltd.), UVX-272 (manufactured by Nanmoto Chemical Co., Ltd.), and Surflon S-611 (AGC) are mentioned as a commercially available person. Made by Seimi Chemical Co., Ltd.).

In order to improve the durability of the element electrode, the sealing agent for an organic EL display element of the present invention may contain a compound or ion exchange reaction with an acid generated in a sealant for an organic EL display element, within a range not inhibiting the object of the present invention. Resin.

Examples of the compound which reacts with the generated acid include a substance neutralized with an acid, for example, an alkali metal carbonate or hydrogencarbonate, or an alkaline earth metal carbonate or hydrogencarbonate. Specifically, for example, calcium carbonate, calcium hydrogencarbonate, sodium carbonate, sodium hydrogencarbonate or the like can be used.

As the ion exchange resin, any of a cation exchange type, an anion exchange type, and an amphoteric exchange type can be used, and a cation exchange type capable of adsorbing chloride ions is particularly preferable. Or gender exchange type.

Further, the sealant for an organic EL display device of the present invention may contain a hardening retarder, a reinforcing agent, a softening agent, a plasticizer, a viscosity adjusting agent, an ultraviolet absorber, and an antioxidant as needed within a range not inhibiting the object of the present invention. And other known additives.

As a method of producing the sealant for an organic EL display device of the present invention, for example, a method such as a homogeneous phase disperser, a homomixer, a universal mixer, a planetary mixer, a kneader, or a three-roll mill can be used. An additive such as a cationically polymerizable compound, a cationic polymerization initiator, and optionally a stabilizer or a decane coupling agent are mixed.

The preferred lower limit of the viscosity at 25 ° C measured by the E-type viscometer for the sealant for organic EL display elements of the present invention is 50 mPa. s, the upper limit is preferably 250mPa. s. When the viscosity is within this range, the sealing agent for an organic EL display device of the present invention is more excellent in coatability and transparency. The lower limit of the above viscosity is 70 mPa. s, the upper limit is better 120mPa. s.

In addition, the viscosity can be suitably selected from 1 to 100 rpm by using the CPIC cone plate by using the VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) as an E-type viscometer, according to the optimum torque of each viscosity region. The number of revolutions was measured.

The sealant for an organic EL display device of the present invention can be preferably used as an in-plane sealant which is coated with a laminate having an organic light-emitting material layer and sealed.

According to the present invention, it is possible to provide a sealant for an organic electroluminescence display element which is capable of suppressing generation of outgas and having excellent storage stability and coating properties.

Hereinafter, the present invention will be described in more detail by way of examples, but the invention is not limited thereto.

(Example 1)

Using a stirring mixer ("AR-250" manufactured by Thinky Co., Ltd.), 60 parts by weight of the compound represented by the above formula (1-1) ("Celloxide 8000" manufactured by Daicel Co., Ltd.) as a cationically polymerizable compound and the above formula ( 1-2) 40 parts by weight of a compound ("Celloxide 2021P" manufactured by Daicel Co., Ltd.), and dimethylphenyl (4-methoxybenzyl) ammonium tetrakis(pentafluorobenzene) as a thermal cationic polymerization initiator 0.5 parts by weight of a borate ("CXC-1821" manufactured by King Industries Co., Ltd.) was uniformly stirred and mixed at a stirring speed of 3000 rpm to prepare a sealant for an organic EL display device.

(Examples 2 to 5, Comparative Examples 1 to 9)

The materials described in Tables 1 and 2 were stirred and mixed in the same manner as in Example 1 based on the blending ratios shown in Tables 1 and 2 to prepare organic ELs of Examples 2 to 5 and Comparative Examples 1 to 9. A sealing agent for display elements.

<evaluation>

The following evaluations were performed on the respective sealants for organic EL display elements obtained in the examples and the comparative examples. The results are shown in Tables 1 and 2.

(1) Viscosity

For each of the sealants for organic EL display elements obtained in the examples and the comparative examples, the viscosity at 25 ° C was measured using an E-type viscometer ("VISCOMETER TV-22" manufactured by Toki Sangyo Co., Ltd.).

(2) Coating properties

Using a pipette, 0.1 mL of each of the organic EL display element sealing agents obtained in the examples and the comparative examples was applied onto a glass substrate, and the diameter of the flattening after one minute was measured. When the diameter is 20 mm or more, it is set to "◎", and when it is 15 mm or more and less than 20 mm, it is set to "○", and when it is 10 mm or more and less than 15 mm, it is set to "△", and it is less than 10 mm. In the case of "X", the coating property was evaluated.

(3) preservation stability

For each of the sealants for organic EL display elements obtained in the examples and the comparative examples, an E-type viscometer ("VISCOMETER TV-22" manufactured by Toki Sangyo Co., Ltd.) was used, and the initial viscosity after 25 ° C was just manufactured and 25 ° C. The viscosity at the time of storage for one week was measured, and the viscosity (25 ° C, viscosity after storage for one week) / (initial viscosity) was defined as the viscosity change rate, and the case where the viscosity change rate was less than 1.2 times was set to "◎", and In the case of 1.2 times or more and less than 1.5 times, it is set to "○", and when it is 1.5 times or more and less than 2.0 times, it is set to "△", and when it is 2.0 times or more, it is set to "X", and it is saved. Stability was evaluated.

(4) Sturability

In the sealing agent for each of the organic EL display elements obtained in the examples and the comparative examples, an epoxy group reaction was carried out by using an infrared spectroscopic device ("UMA600" manufactured by Agilent Technologies Co., Ltd.), and the epoxy group was cured by heating at 100 ° C for 30 minutes. The rate (the peak reduction rate derived from the epoxy group) was measured, and the case where the reaction rate was 90% or more was set to "◎", and the case where 80% or more and less than 90% was set to "○", 60%. In the case where the above is less than 80%, it is set to "△", and the case where the amount is less than 60% is set to "X", and the hardenability is evaluated.

(5) Anti-gas release prevention

Each of the organic EL display element sealing agents obtained in the examples and the comparative examples was weighed and placed in a vial and sealed in a vial, and then heated at 100 ° C for 30 minutes to be hardened. Further, the vial was heated in a constant temperature oven at 85 ° C for 100 hours, and the vaporized component in the vial was measured using a gas chromatography mass spectrometer ("JMS-Q1050" manufactured by JEOL Ltd.).

When the amount of the gasification component is less than 30 ppm, it is set to "◎", and when it is 30 ppm or more, if it is less than 50 ppm, it is set to "○", and if it is 50 ppm or more, if it is less than 100 ppm, it is set to "△", and it is 100 ppm. The above situation is set to "X" to evaluate the outgassing prevention property.

[Industrial availability]

According to the present invention, it is possible to provide a sealant for an organic electroluminescence display element which is capable of suppressing generation of outgas and having excellent storage stability and coating properties.

Claims (4)

A sealant for an organic electroluminescence display device, comprising a cationically polymerizable compound and a thermal cationic polymerization initiator, wherein the cationically polymerizable compound contains a compound represented by the following formula (1-1) and a formula (1-2) The compound represented by the above-mentioned thermal cationic polymerization initiator is a quaternary ammonium salt of a borate type. The sealant for an organic electroluminescence display device according to the first aspect of the invention, wherein the counter anion is a borate-based quaternary ammonium salt dimethylphenyl (4-methoxybenzyl) ammonium tetra (five) Fluorophenyl) borate. The sealant for an organic electroluminescence display device according to the first or second aspect of the invention, wherein the ratio of the compound represented by the formula (1-1) to the compound represented by the formula (1-2) is a weight ratio, A compound represented by the formula (1-1): a compound represented by the above formula (1-2) = 9:1 to 1:4. The sealant for an organic electroluminescence display device according to the first, second or third aspect of the invention, wherein the compound represented by the formula (1-1) and the formula (1-2) in 100 parts by weight of the entire cationically polymerizable compound The total content of the compounds indicated is 60 parts by weight or more.