JP2022062864A - Desiccant composition, sealing structure, and organic el element - Google Patents

Abstract

To stabilize viscosity of a desiccant composition for a long time in a production process for stable coating.SOLUTION: A desiccant composition contains a water-capturing component containing oxide particles containing an oxide of alkali earth metal, and hydrogen-modified silicone that is represented by a following formula (1), and has a structural unit where R1 is an alkyl group having 1 to 3 carbon atoms.SELECTED DRAWING: None

Description

The present invention relates to a desiccant composition, a sealing structure, and an organic EL device.

Various methods for preventing the intrusion of water into the light emitting portion of the organic EL element have been studied. For example, Patent Document 1 is a desiccant composition having a (meth) acrylic group and containing a high molecular weight (meth) acrylic compound liquid at 25 ° C. and oxide particles containing an oxide of an alkaline earth metal. Discloses the formation of a desiccant layer for organic EL elements.

Japanese Unexamined Patent Publication No. 2018-106961

The desiccant composition for forming the desiccant layer may thicken during storage or use. Since the desiccant layer is often formed by applying the desiccant composition, it is desirable in the manufacturing process that the viscosity of the desiccant composition is stable for a long time for stable application.

で表される構成単位を有するハイドロジェン変性シリコーンとを含む、乾燥剤組成物を提供する。Ｒ^１は炭素数１～３のアルキル基である。 One aspect of the present invention is a water catching component containing oxide particles containing an oxide of an alkaline earth metal, and the following formula (1):

Provided is a desiccant composition comprising a hydrogen-modified silicone having a structural unit represented by. R ¹ is an alkyl group having 1 to 3 carbon atoms.

Another aspect of the present invention is a pair of substrates facing each other, a sealing sealant that seals the outer peripheral portion of the pair of substrates, and a sealing sealant inside the sealing sealant between the pair of substrates. Provided is a sealing structure comprising a desiccant layer formed from the desiccant composition provided.

Yet another aspect of the present invention is an element substrate, a sealing substrate arranged to face the element substrate, and a sealing sealant for sealing the element substrate and the outer peripheral portion of the sealing substrate. A light emitting portion having an organic layer and a pair of electrodes sandwiching the organic layer provided on the element substrate inside the sealing sealant, and the element substrate and the sealing substrate inside the sealing sealant. Provided is an organic EL device provided between the above and comprising a desiccant layer formed from the desiccant composition.

According to one aspect of the present invention, there is provided a desiccant composition capable of having a stable viscosity for a long period of time.

It is a schematic cross-sectional view which shows one Embodiment of an organic EL element.

Hereinafter, some embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

で表される構成単位を有するハイドロジェン変性シリコーンとを含む。式（１）中のＲ^１は炭素数１～３のアルキル基であり、メチル基であってもよい。 Desiccant Composition The desiccant composition according to the embodiment comprises a water-catching component containing oxide particles containing an oxide of an alkaline earth metal, and the following formula (1):

Includes hydrogen-modified silicone having a structural unit represented by. R ¹ in the formula (1) is an alkyl group having 1 to 3 carbon atoms, and may be a methyl group.

Oxide particles are particles containing an oxide of an alkaline earth metal as a main component, which can impart water replenishment performance to the oxide particles. The oxide particles usually contain an oxide of 80% by mass or more, or 90% by mass or more, of an alkaline earth metal based on the mass of the oxide particles. The oxide particles can contain oxides of one kind or two or more kinds of alkaline earth metals having different components. Examples of the oxide of the alkaline earth metal include calcium oxide (CaO), strontium oxide (SrO), magnesium oxide (MgO), and barium oxide (BaO). The oxide particles may be calcium oxide particles, strontium oxide particles, or both. The calcium oxide particles usually contain 80% by mass or more, or 90% by mass or more, calcium oxide based on the mass of the calcium oxide particles. The strontium oxide particles usually contain 80% by mass or more, or 90% by mass or more, of strontium oxide based on the mass of the strontium oxide particles.

The average particle size of the oxide particles is not particularly limited, but may be, for example, 0.01 to 30 μm. When the average particle size of the oxide particles is in this range, higher water catching performance tends to be obtained. From the same viewpoint, the average particle size of the oxide particles may be 0.1 μm or more, 0.5 μm or more, or 1 μm or more, and may be 20 μm or less, 10 μm or less, or 5 μm or less.

In the present specification, the average particle size of the oxide particles means the median value of the volume distribution measured by the dynamic light scattering type particle size distribution meter. This average particle size is a value measured by using a dispersion prepared by dispersing oxide particles in a predetermined dispersion medium.

The specific surface area of the oxide particles may be 5 to 60 m ² / g. When the specific surface area is 5 to 60 m ² / g, the desiccant composition can have even better water catching performance. From the same viewpoint, the specific surface area of the oxide particles may be 10 m ² / g or more or 15 m ² / g or more, 50 m ² / g or less, 40 m ² / g or less, or 35 m ² / g or less. You may. The specific surface area here means a value measured by the BET method.

The content of the oxide particles in the desiccant composition is 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, or 60 based on the mass of the desiccant composition. It may be 95% by mass or less, 90% by mass or less, 85% by mass or less, or 80% by mass or less. The total content of calcium oxide particles and strontium oxide may be within these numerical ranges. Even a desiccant composition containing a large amount of oxide particles can have good viscosity stability by introducing a hydrogen-modified silicone. Here, when the desiccant composition contains a solvent, the content of each component based on the mass of the desiccant composition referred to in the present specification is the total mass of the components of the desiccant composition excluding the solvent. Means a value based on.

The hydrogen-modified silicone may be a silicone compound having a polysiloxane chain composed of a structural unit represented by the above formula (1) and a structural unit represented by the following formula (2). R ¹ in equation (2) is synonymous with R ¹ in equation (1). The hydrogen groups bonded to the silicon atoms interact with the oxide particles while the polysiloxane chains of the hydrogen-modified silicone are well compatible with each other. Due to these actions, it is considered that the hydrogen-modified silicone contributes to the improvement of the viscosity stability of the desiccant composition.

The viscosity of the hydrogen-modified silicone at 25 ° C. may be, for example, 0.01 to 5 Pa · s. When the viscosity of the hydrogen-modified silicone is within this range, an excellent effect can be obtained in terms of the applicability of the desiccant composition. In the present specification, the viscosity is a value measured by a rotational viscometer such as a B-type viscometer or a leometer.

The content of the hydrogen-modified silicone may be 30% by mass or less based on the mass of the desiccant composition. When the content of the hydrogen-modified silicone is 30% by mass or less, the coating property of the desiccant composition tends to be more excellent. From the same viewpoint, the content of the hydrogen-modified silicone may be 20% by mass or less based on the mass of the desiccant composition. From the viewpoint of improving the stability of viscosity, the content of the hydrogen-modified silicone may be 1% by mass or more, or 2% by mass or more, based on the mass of the desiccant composition.

The desiccant composition may further contain a polymerizable compound having one or more polymerizable unsaturated groups. The reaction of this polymerizable compound cures the desiccant composition, and a more stable desiccant layer can be formed. The polymerizable compound may be a silicone compound having a polysiloxane chain and a substituent having a polymerizable unsaturated group bonded to the polysiloxane chain. For example, the polymerizable compound may be a (meth) acrylic-modified silicone represented by the following formula (3). In formula (3), R ² represents a divalent organic group, R ³ represents a hydrogen atom or a methyl group, and x represents an integer of 1 or more. R ² may be an alkylene group.

The content of the polymerizable compound (for example, (meth) acrylic-modified silicone) may be 12 to 48% by mass based on the mass of the desiccant composition.

When the desiccant composition contains the above polymerizable compound, the desiccant composition may further contain a photopolymerization initiator. Examples of the photopolymerization initiator include 1-hydroxy-cyclohexyl-phenyl-ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 2,2-dimethoxy-1, 2-Diphenylethane-1-one, 2-methyl-1 [4- (methylthio) phenyl] -2-molyphorinopropane-1-one, and 1- [4- (2-hydroxyethoxy) -phenyl]- 2-Hydroxy-2-methyl-1-propane-1-one can be mentioned. The content of the photopolymerization initiator may be, for example, 0.01 to 10% by mass with respect to the content of the polymerizable compound in the desiccant composition.

The desiccant composition may further contain dimethyl silicone. The desiccant composition containing dimethyl silicone is more likely to have a viscosity suitable for coating. The viscosity of dimethyl silicone at 25 ° C. may be 0.9 to 100 Pa · s. The content of dimethyl silicone may be 1 to 40% by mass based on the mass of the desiccant composition.

The desiccant composition can be in the form of a paste at 25 ° C. When the desiccant composition is in the form of a paste, the desiccant layer can be more easily formed by coating in the minute airtight space of the organic EL element. The viscosity of the desiccant composition at 25 ° C. may be 5 to 500 Pa · s. When the viscosity of the desiccant composition at 25 ° C. is in this range, the desiccant layer can be more easily formed by coating. From the same viewpoint, the viscosity of the desiccant composition may be 10 Pa · s or more, 50 Pa · s or more, 400 Pa · s or less, or 300 Pa · s or less.

Sealing structure The sealing structure according to the embodiment includes a pair of substrates arranged to face each other, a sealing sealant that seals the outer periphery of the pair of substrates, and a pair of substrates inside the sealing sealant. It is provided with a desiccant layer provided between the two. The desiccant layer can be a layer formed by the desiccant composition according to the above-described embodiment. The desiccant layer may be a cured product of the desiccant composition.

The encapsulation structure of the present embodiment can be particularly suitably used when encapsulating a device that is susceptible to moisture. Examples of such devices include organic electronic devices such as organic EL devices, organic semiconductors, and organic solar cells.

Organic EL Element FIG. 1 is a schematic cross-sectional view showing an embodiment of an organic EL element. The organic EL element 1 shown in FIG. 1 sandwiches an element substrate 2, a sealing substrate 3 arranged to face the element substrate 2, and an organic layer 4 and an organic layer 4 provided on the element substrate 2. A light emitting portion 10 having an anode 5 and a cathode 6, a sealing sealant 8 for sealing the outer peripheral portions of the element substrate 2 and the sealing substrate 3, and a sealing sealing agent 8 provided on the sealing substrate 3 inside the sealing sealing agent 8. It is an organic EL element having a so-called hollow sealing structure, which is composed of the drying agent layer 7. The desiccant layer 7 can be a cured product formed from the desiccant composition of the above embodiment. However, the organic EL element is not limited to the hollow sealing structure as shown in FIG. 1, and has, for example, a desiccant layer filled in an airtight space surrounded by an element substrate, a sealing substrate, and a sealing seal layer. It may be an organic EL element having a filling structure.

In the organic EL element 1, a normal configuration can be applied to elements other than the desiccant layer 7, and an example thereof will be briefly described below.

The element substrate 2 is made of a rectangular glass substrate having insulating and translucent properties, and an anode 5 (electrode) is formed on the element substrate 2 by ITO (Indium Tin Oxide) which is a transparent conductive material. There is. The anode 5 is formed by patterning an ITO film formed on the element substrate 2 by a PVD (Physical Vapor Deposition) method such as a vacuum vapor deposition method or a sputtering method into a predetermined pattern shape by etching by a photoresist method. Will be done. A part of the anode 5 as an electrode is drawn out to the end of the element substrate 2 and connected to a drive circuit (not shown).

An organic layer 4 which is a thin film containing an organic light emitting material is laminated on the upper surface of the anode 5 by, for example, a PVD method such as a vacuum vapor deposition method or a resistance heating method. The organic layer 4 may be formed from a single layer or may be formed from a plurality of layers having different functions. The organic layer 4 in the present embodiment has a four-layer structure in which a hole injection layer 4a, a hole transport layer 4b, a light emitting layer 4c, and an electron transport layer 4d are laminated in this order from the anode 5 side. The hole injection layer 4a is formed of, for example, copper phthalocyanine (CuPc) having a film thickness of several tens of nm. The hole transport layer 4b is formed of, for example, bis [N- (1-naphthyl) -N-phenyl] benzidine (α-NPD) having a film thickness of several tens of nm. The light emitting layer 4c is formed of, for example, tris (8-quinolinolat) aluminum (Alq ₃ ) having a film thickness of several tens of nm. The electron transport layer 4d is formed of, for example, lithium fluoride (LiF) having a film thickness of several nm. A light emitting portion is formed by a laminated body in which the anode 5, the organic layer 4, and the cathode 6, which will be described later, are laminated in this order.

A cathode 6 (electrode), which is a metal thin film, is laminated on the upper surface of the organic layer 4 (electron transport layer 4d) by a PVD method such as a vacuum vapor deposition method. Examples of the material of the metal thin film include simple metals having a small work function such as Al, Li, Mg, and In, and alloys having a small work function such as Al—Li and Mg—Ag. The cathode 6 is formed with a film thickness of, for example, several tens of nm to several hundred nm or 50 nm to 200 nm. A part of the cathode 6 is pulled out to the end of the element substrate 2 and connected to the drive circuit.

The sealing substrate 3 is arranged so as to face the element substrate 2 with the organic layer 4 interposed therebetween, and the outer peripheral portions of the element substrate 2 and the sealing substrate 3 are sealed with the sealing sealant 8. As the sealing sealant, for example, an ultraviolet curable resin can be used. Further, the desiccant layer 7 is provided on a part or all of the sealing substrate 3 inside the sealing sealant 8. The desiccant layer 7 is formed by applying the desiccant of the above embodiment. The desiccant layer 7 is formed with a film thickness of 1 to 300 μm.

For the organic EL element, for example, the desiccant composition is applied on the sealing substrate 3 to form the desiccant composition layer, and the sealing sealant 8 is applied so as to surround the desiccant composition layer. The desiccant composition layer is cured to form the desiccant layer 7, the element substrate 2 on which the organic layer 4 and the like are laminated and the sealing substrate 3 are bonded together, and if necessary, a sealing sealant. It can be produced by a method including curing 8. The desiccant composition and the sealing sealant can be applied, for example, using a dispenser, and the application is preferably performed in a glove box substituted with nitrogen having a dew point of −76 ° C. or lower. The desiccant composition applied may contain a solvent, but is typically substantially solvent-free. The sealing sealant can usually be cured by UV irradiation and / or heating.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

1. 1. Preparation of desiccant composition The following raw materials were prepared. The viscosity of each raw material used as a binder is the viscosity at 25 ° C. These were mixed at the compounding ratios shown in Tables 1 to 5, and the mixture was stirred to obtain a white paste-like desiccant composition. The compounding ratio shown in each table is the ratio (% by mass) of the amount of each component based on the mass of the desiccant composition.
(1) Water catching component-Calcium oxide particles (CaO, average particle size 1.7 μm, specific surface area 15 m ² / g)
-Strontium oxide particles (SrO, average particle size 2.5 μm, specific surface area 1.7 m ² / g)
(2) Binder / hydrogen-modified silicone (viscosity 1 Pa · s)
・ Methacryl-modified silicone (viscosity 55 mPa · s)
-Dimethyl silicone (component with viscosity 100 Pa · s: component with viscosity 10 Pa · s = 60:40 (mass ratio) mixture)

2. 2. Viscosity stability of desiccant composition Each desiccant composition was allowed to stand in an environment at room temperature (25 ° C.), and the change in viscosity at 25 ° C. in that state was measured over time. Each table shows the viscosity at the initial stage (0 hour) and after 168 hours, and the viscosity increase rate as the measurement result of the viscosity. The viscosity increase rate is a relative value (%) of the viscosity after 168 hours with respect to the initial viscosity. The desiccant composition of each example containing the side chain hydrogen-modified silicone maintained a state of little change in viscosity for a long period of time. The desiccant compositions of Examples 1-7 and 2-7 having a hydrogen-modified silicone content of 40% by mass caused a slight stringing. Therefore, it can be said that when the content of the hydrogen-modified silicone is moderately small, a desiccant composition having better coatability tends to be obtained.

1 ... organic EL element, 2 ... element substrate, 3 ... sealing substrate, 4 ... organic layer, 4a ... hole injection layer, 4b ... hole transport layer, 4c ... light emitting layer, 4d ... electron transport layer, 5 ... anode, 6 ... Cathode, 7 ... Drying agent layer, 8 ... Sealing sealant.

Claims (7)

Water catching components containing oxide particles containing oxides of alkaline earth metals,
The following formula (1):

A hydrogen-modified silicone having a constituent unit, wherein R ¹ is an alkyl group having 1 to 3 carbon atoms.
A desiccant composition comprising. The desiccant composition according to claim 1, wherein the oxide particles are calcium oxide particles, strontium oxide particles, or both. The desiccant composition according to claim 1 or 2, wherein the content of the hydrogen-modified silicone is 30% by mass or less based on the mass of the desiccant composition. The desiccant composition according to any one of claims 1 to 3, further comprising a polymerizable compound having one or more polymerizable unsaturated groups. The desiccant composition according to any one of claims 1 to 4, further comprising dimethyl silicone. A pair of boards arranged facing each other and
A sealing sealant that seals the outer peripheral portion of the pair of substrates,
A desiccant layer formed from the desiccant composition according to any one of claims 1 to 5, which is provided between the pair of substrates inside the sealing sealant.
A sealing structure comprising. With the element board
A sealing substrate arranged to face the element substrate and
A sealing sealant that seals the element substrate and the outer peripheral portion of the sealing substrate, and
A light emitting portion provided on the element substrate inside the sealing sealant and having an organic layer and a pair of electrodes sandwiching the organic layer.
A desiccant layer provided between the element substrate and the encapsulation substrate inside the sealing sealant and formed from the desiccant composition according to any one of claims 1 to 5.
An organic EL element comprising.

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