JP2015166075A - Moisture absorbent, desiccant, organic el sheet and manufacturing method of moisture absorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moisture absorbent and a desiccant which hardly expands even when absorbing moisture, suppresses influence of a strong alkaline product which is produced after absorbing moisture and can keep moisture absorbing ability for a long term, in the desiccant which is mixed in an adhesive, filler, a sheet-like adhesive resin, etc. for adhering a base plate sheet of an organic EL sheet and a sealing sheet, and to provide the organic EL sheet which is provided by using the moisture absorbent and desiccant and is hardly deteriorated for a long term.SOLUTION: A moisture absorbent includes a moisture-permeable core layer (1) made of an oxide film containing silica which has air-permeable pores. The core layer (1) surrounds a hygroscopic material part (2) containing an oxide which includes calcium oxide or magnesium oxide and a void part (3) for expanding when the hygroscopic material performs a hygroscopic reaction. The desiccant has a resin into which the moisture absorbent is kneaded. An organic EL sheet contains the moisture absorbent on an inner part of a sealing base plate or between the sealing base plate and the organic EL element.

Description

  The present invention relates to a hygroscopic agent and a desiccant encapsulated in an organic EL device or the like.

In the configuration of a basic organic electroluminescence (hereinafter abbreviated as “organic EL”) sheet, an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, a cathode, An organic EL element in which (in addition, a passivation layer if necessary) is sequentially laminated is formed, and the sealing sheet is an adhesive resin or low melting point glass that is cured by light or heat, and the organic EL element forming surface of the substrate sheet It is bonded to face.
On the contrary, there is a case where the substrate sheet is configured from the cathode side, or a driving circuit by a thin film transistor is incorporated on the substrate sheet. At least one of the substrate sheet or the sealing sheet and at least one of the anode or the cathode is translucent, and the organic EL light emission is taken out from either the substrate sheet side or the sealing sheet side, or from the end face of the substrate.

Organic EL elements are particularly susceptible to deterioration due to moisture. The cause of this is that an electron injection layer is injected with an alkali metal such as Li, Na, Cs or the like, which easily deteriorates by reacting with moisture, or an alkaline earth metal compound selected from Mg, Ca, Sr, Ba. This is because it is used as a material. Therefore, strict sealing is performed in order to obtain a long-life organic EL element, and a desiccant containing a hygroscopic agent is disposed in the sealed space (see Patent Documents 1 to 3).
As the hygroscopic agent, a chemical reaction type such as calcium oxide, magnesium oxide, barium oxide, an organic metal containing aluminum or boron, or a physical adsorption type such as zeolite is used alone or in combination. However, the physical adsorption type has a problem of easily desorbing adsorbed water in a low moisture atmosphere and a high temperature environment, and an irreversible chemical reaction type is mainly used.

Among chemical reaction type moisture absorbents, barium oxide has higher moisture absorption capacity than calcium oxide, but is a deleterious substance and difficult to use due to the harmfulness of barium ions. Magnesium oxide has high safety and moisture absorption capacity, but moisture absorption rate is slower than calcium oxide. Calcium oxide has a higher initial moisture absorption rate and higher safety than magnesium oxide, but has a problem in long-term sustainability.
The desiccant is mounted on the organic EL sheet using a sealing sheet coated with a desiccant obtained by kneading the moisture absorbent component (hygroscopic material) into the resin, or a desiccant molded into a sheet or tape. And the organic EL element substrate sheet on which the organic EL element is formed are overlapped and bonded with a low moisture-permeable adhesive. At that time, the organic EL element and the desiccant are in contact with each other so that a space is provided and bonded so as not to physically and chemically damage the organic EL element.

However, in order to provide a space for bonding, a thick sealing substrate such as a countersink glass provided with a space for attaching a desiccant sheet or a metal can provided with a recessed portion by pressing is required, and the substrate processing cost Increases and the flexibility (flexibility) of the organic EL sheet is impaired. In addition, by providing the space, heat radiation from the sealing sheet side is insufficient, and deterioration may be promoted due to a temperature increase of the organic EL element in the case of emitting light with high luminance.
Therefore, a gel-like desiccant in which a hygroscopic agent is dispersed is provided so as to be in close contact with the organic EL element and the sealing sheet facing the surface to improve heat dissipation (see Patent Document 4). In addition, the chemically reactive moisture absorbent and the desiccant react with moisture due to moisture absorption to expand the volume (see Patent Document 5). Therefore, when the organic EL element substrate sheet and the sealing sheet are partially peeled off, the substrate sheet and the sealing sheet made of a resin film, a desiccant sheet containing a chemically reactive moisture absorbent, or a tape, or a resin or gel When pasted together, there was a risk of warping or distortion due to uneven water absorption. Calcium oxide, which is often used as a hygroscopic agent, changes to calcium hydroxide due to water absorption and becomes strongly alkaline, and decomposes organic ester element materials, urethane bonds, siloxane bonds, amide bonds, etc. of organic substances that come into contact with organic EL element materials and There was also a concern of causing deterioration of the adhesive resin. In addition, even when a desiccant having a strong hygroscopic capacity is initially sealed, when a resin film-made substrate sheet or sealing sheet is used, a small amount of moisture is continuously present compared to an inorganic glass substrate. There was a problem in maintaining moisture absorption ability for a long time because it easily penetrates.

Japanese Patent Laid-Open No. 9-148066 JP 2002-280166 A Japanese Patent No. 3885150 Japanese Patent No. 5111201 Special table 2011-503820 gazette

  An object of the present invention is to provide a hygroscopic agent or a desiccant that hardly expands in volume even after moisture absorption, suppresses deterioration of the binder resin, and maintains moisture absorption capacity for a long period of time, or an organic EL sheet using the same. .

As means for solving the above problems, a hygroscopic agent according to one embodiment of the present invention includes a hygroscopic material portion containing a metal oxide and a moisture-permeable shell layer made of a porous oxide containing silicon. The shell layer surrounds the hygroscopic material portion and a void portion for expanding when the hygroscopic material portion undergoes a hygroscopic reaction.
In the desiccant according to one embodiment of the present invention, the above-described hygroscopic agent is kneaded.
In the organic EL sheet according to one embodiment of the present invention, an organic EL element is sandwiched between a substrate sheet and a sealing sheet composed of one or a plurality of sheets, and between the plurality of substrate sheets and the sealing sheet, or organic At least the above-mentioned hygroscopic agent is included between the EL element and the sealing sheet.

The hygroscopic agent which concerns on 1 aspect of this invention contains the oxide of calcium or magnesium as a metal oxide. One aspect of the manufacturing method will be described below. First, a carbonate containing calcium or magnesium as a cation is used as a nucleus. The fine particles having a porous oxide film as a shell layer on the surface of the carbonate nucleus are heated to a temperature of 300 ° C. or higher and 650 ° C. or lower to decarboxylate the carbonate nucleus surrounded by the shell layer to form an oxide. By thermally decomposing, a hygroscopic material portion and a void portion are formed inside the shell layer.
Further, in the method for producing a hygroscopic agent according to one embodiment of the present invention, particles having a shell layer made of an oxide on the surface of carbonate crystal particles containing calcium or magnesium as a cation, and having a carbon dioxide partial pressure of 0.1 or more Firing at a temperature of 500 ° C. or higher and 650 ° C. or lower in the atmosphere of Thereafter, the carbonate particles surrounded by the shell layer are decarboxylated and thermally decomposed into oxides by heating to a temperature of 300 ° C. or higher and 500 ° C. or lower in an atmosphere or vacuum of carbon dioxide partial pressure of 0.0001 atm.

  According to one embodiment of the present invention, the hygroscopic agent has a shell on the surface of the hygroscopic agent particles, and has a hygroscopic material containing a calcium or magnesium oxide and voids therein. The hygroscopic material in the hygroscopic agent expands in volume by reacting with water when absorbing moisture, but can expand in the void surrounded by the shell, thereby suppressing the expansion of the hygroscopic agent itself. Therefore, long-term expansion | swelling of an adhesive dry sheet | seat can be suppressed, and the curvature and distortion of the organic EL sheet | seat by the difference in the expansion amount by peeling between board | substrates or a partial moisture absorption amount can be suppressed.

It is a schematic diagram of the cross section which shows an example of a structure of the hygroscopic agent which concerns on 1 aspect of this invention. 6 is a flowchart illustrating an example of a manufacturing process of a hygroscopic agent according to one embodiment of the present invention. It is a phase diagram which shows the relationship between the equilibrium temperature in which calcium carbonate turns into calcium oxide and carbon dioxide, and carbon dioxide partial pressure. It is sectional drawing which shows an example of a structure of the organic electroluminescent sheet which concerns on 1 aspect of this invention. It is sectional drawing which shows another example of a structure of the organic electroluminescent sheet which concerns on 1 aspect of this invention.

<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings.
As shown in FIGS. 1A to 1D, the hygroscopic agent according to this embodiment has a moisture permeable shell layer 1 made of a porous oxide containing silicon on the surface of the hygroscopic agent particles 4. The shell layer 1 surrounds a hygroscopic material portion 2 containing calcium oxide or magnesium oxide and a void portion 3 for expanding when the hygroscopic material portion 2 undergoes a hygroscopic reaction. The gap 3 becomes a space for expanding when calcium oxide or magnesium oxide absorbs moisture and becomes hydroxide. Therefore, expansion of the hygroscopic particles 4 themselves can be suppressed.

The size of the hygroscopic particles 4 according to this embodiment is a set of particles containing 50% or more of particles having a diameter or major axis of 15 nm to 10 μm as observed by microscopic observation. More preferably, it is a set of particles containing 50% or more of a particle size of 1 μm or less having a large specific surface area and a high moisture absorption property.
Alternatively, the sheet may be formed by dispersing in a resin. In the case of improving the light transmittance when the sheet is disposed on the organic EL light extraction side, the diameter of the hygroscopic particles 4 is mainly 200 nm or less, more preferably 100 nm or less, and still more preferably 50 nm or less. Thus, it is more preferable to use one synthesized by adjusting the reaction time, reaction temperature, pH during the reaction, solution concentration, stirring method and heating method.

The manufacturing process of the hygroscopic agent according to the present embodiment will be described with reference to FIG.
(Nucleation)
As the material used for the core, calcium carbonate, magnesium carbonate, and double salts thereof can be used. In addition to the solid body, the core can be a hollow body. It is desirable that the carbonate used as the nucleus is not one in which the surface is uneven, in order to form a shell uniformly.
As calcium carbonate, nano-sized particles of 1 μm or less in the form of rectangular, cubic, columnar, or rhombohedral monolithic or polycrystalline calcite of synthetic calcium carbonate (light calcium carbonate) with fine particles Spherical particles having a high surface smoothness and having a diameter of 10 μm or less can be used. Commercially available calcium carbonates such as colloidal colloidal calcium carbonate manufactured by Shiroishi Kogyo (registered trademark) and colloid / light calcium carbonate manufactured by Maruo Calcium (registered trademark) can also be used. In addition, synthetic calcium carbonate whose surface is modified with a fatty acid or alkoxide to improve dispersibility in the resin can also be used.

As magnesium carbonate, synthetic magnesite manufactured by Kamishima Chemical Industry (registered trademark) having a median particle size of 10 μm or less can be used.
As for the size of the particles, particles having a diameter or major axis of 1 μm or less that are difficult to precipitate in the shell formation step and have high dispersibility can be used more preferably. A synthesis example of monodispersed spherical calcium carbonate particles having a uniform particle diameter of about 1 μm is shown in “Materials Chemistry and Physics, Vol. 88, pages 1-4, 2004”. In the above document, 80 ml of 0.5 g / L polymaleic anhydride aqueous solution and 1.28 ml of 0.5 M sodium carbonate aqueous solution are adjusted to pH 10 with 1 M hydrochloric acid and sodium hydroxide aqueous solution. It is synthesized by mixing 28 ml with vigorous stirring.

Regarding a method for producing a hollow body, Japanese Patent No. 4660745 discloses a method for producing a hollow / spherical calcium carbonate having a porous shell made of calcium carbonate crystals having a size of 5 nm to 50 nm and having a diameter of 1 μm to 10 μm. . JP 2013-216545 A discloses a method for producing hollow calcium carbonate particles having a shell thickness of 10 nm to 250 nm and a particle size of 0.3 μm to 10 μm.
The obtained calcium carbonate nuclei are dehydrated with a centrifuge after aging and used in the next shell formation step.

(Shell formation process)
The shell of the hygroscopic agent according to the present embodiment uses a calcium or magnesium carbonate or a double salt crystal as a core (also referred to as a core) to form a film on the surface by a sol-gel method (template method), and then fired. This can be done.
A well-known method can be used about the shell formation method on the calcium carbonate particle by a template method. For example, Fuji Lab's laboratory at Nagoya Institute of Technology, a method of forming a silica hollow particle by dissolving a nucleus with an acid by forming a shell with a porous silica film by a sol-gel method using calcium carbonate as a nucleus by a template method, Since it is disclosed in Japanese Patent No. 5017650, Japanese Patent No. 4816634, WO2013 / 073475, JP2013-237601A, WO2012 / 121130, JP2011-168437A, etc. Can be helpful.

The thickness of the shell is preferably formed in the range of 5 nm to 500 nm. When the thickness of the shell is less than 5 nm, the strength of the shell is low, and the desiccant particles may break due to thermal expansion or contraction in the secondary firing step. On the other hand, when the shell thickness is thicker than 500 nm, the proportion of the hygroscopic material in the hygroscopic agent according to the present embodiment decreases, the moisture absorption capacity becomes insufficient, and the permeation rate of the shell of water molecules becomes slow, so that the hygroscopic ability. Decreases.
Depending on the required properties, use a mixture of hygroscopic particles with a thin shell with a fast initial moisture absorption rate and a small particle size, and hygroscopic particles with a thick shell with a long moisture absorption period but a long moisture absorption period and a large particle size. be able to.

Next, an example of a material for forming a shell made of an oxide film containing silicon on a calcium carbonate particle by a sol-gel method will be described.
First, a tetrafunctional TEOS (tetraethoxysilane), tetra (n-propoxy) silane, or a metal alkoxide such as a condensate thereof is added to a suspension in which calcium carbonate particles are dispersed in an alcohol such as ethanol. A basic catalyst such as sodium carbonate or the like is added to hydrolyze the terminal alkoxy group to cause condensation polymerization (condensation polymerization). At that time, by mixing MTES (methyltriethoxysilane) or the like as a trifunctional alkoxide, the crosslink density of the film can be lowered, and the pore diameter of the film can be adjusted largely.

Further, as a non-silicon-based alkoxide, a metal alkoxide such as triisopropoxyaluminum, tetraisopropoxytitanium, methyltriisopropoxytitanium, tri (n-butoxy) borane, tetra (n-propoxy) zirconium or the like is mixed to make the film fine. The pore diameter, refractive index and strength can also be adjusted.
The catalyst used for hydrolyzing the metal alkoxide can form a polyalkoxide having a high degree of polymerization with an acid catalyst such as hydrochloric acid until the carbonate is added. However, during the shell formation, a carbonate such as calcium carbonate is used. In order to prevent dissolution, it is preferable to react after making the system alkaline by adding a basic catalyst such as ammonia or sodium carbonate.

When calcium carbonate particles that have been surface-modified to improve dispersibility are used as nuclei, modifying groups such as dispersant polymers, organic acids, and alkoxides cover the surface of the nuclei. A reaction system in which a water-soluble organic solvent such as diglyme is mixed may be used to deposit a sol-gel film on calcium carbonate as a core while dissolving the surface modification group.
The film formed by the sol-gel method is a porous film having nanometer-size pores and can pass water molecules.
The pore size of the membrane can be adjusted by adjusting the type of alkoxide (number of functional groups and alkyl substituents), the type and temperature, pH, and reaction rate of the catalyst for depositing the membrane, and adjusting the subsequent firing conditions. it can. Moreover, in order to improve dispersion | distribution of the particle | grains during reaction, you may irradiate an ultrasonic wave.

(Baking process, making hygroscopic agent)
Next, after sintering and densifying the shell of the obtained sol-gel film to increase the strength, the calcium carbonate or magnesium carbonate particles inside the shell are fired and converted to calcium oxide and magnesium oxide after the primary firing step. It becomes a hygroscopic agent through a secondary firing step.
Here, a sol-gel film formed from polysiloxane using TEOS as a raw material can be sintered while maintaining some pores of 1 nm or more and 2 nm or less in the film when heated and fired at about 600 ° C., but is fired at a high temperature. The diameter of the pores of the shell becomes narrower as you go. Moreover, in the case of 700 degreeC heat baking, a pore will be plugged up. This makes it difficult for water molecules to pass through the shell membrane.

  In order to leave pores even at 700 ° C., it is possible to use a trifunctional raw material having an alkyl group that thermally decomposes and volatilizes, such as MTES (methyltriethoxysilane). The pore is blocked and the pore diameter is reduced. Furthermore, at 850 ° C. or higher, calcium carbonate and shell silica start to react to form calcium silicate. Further, since the shell silica has a smaller coefficient of thermal expansion than the core calcium carbonate, the shell is broken by thermal expansion. Therefore, it is preferable to bake at 650 ° C. or lower. More preferably, primary baking is performed at a temperature of 500 ° C. to 600 ° C. for 10 minutes or more.

Here, the reaction from decarboxylation to calcium oxide from calcium carbonate is an equilibrium reaction shown in Formula (1). Since the decarboxylation reaction is an equilibrium reaction, the partial pressure of carbon dioxide gas in the atmosphere affects it.
CaCO ₃ = CaO + CO ₂ (1)
FIG. 3 is a phase diagram showing the relationship between the partial pressure of CO ₂ gas and the temperature with respect to 1 mol of solid calcium carbonate CaCO ₃ . This relationship was obtained by calculation using thermodynamic equilibrium calculation / phase diagram creation software “CaTCalc” (manufactured by National Institute of Advanced Industrial Science and Technology) by Material Design Technology Laboratory.

From this phase diagram, since the partial pressure of carbon dioxide in the atmosphere is about 3 × 10 ⁻⁴ atm, it can be expected that a decarboxylation reaction occurs at a temperature of about 500 ° C. when firing in the atmosphere at 1 atm. If the decarboxylation of the nucleus begins before the shell is sufficiently sintered and strength is increased, the shell contracts as the nucleus contracts. In order to secure a void surrounded by the shell (expansion space when absorbing moisture) in the primary firing process, the shell sol-gel film is first sintered at a sufficiently high temperature so that the pores can be maintained without decarboxylating and decomposing the nucleus. It is necessary to keep it.
The diameter of the pores needs to be at least a diameter through which carbon dioxide and water molecules can pass. The pore diameter of the shell pores after firing is preferably 1 nm or more and 2 nm or less (calculated from the nitrogen gas adsorption isotherm), but is 20 nm or less at most. When the pore size is smaller than 1 nm, it becomes difficult to permeate water molecules, and the moisture absorption rate of the moisture absorbent becomes slow. When the pore size is larger than 20 nm, the water molecule permeates faster and the sustainability as a hygroscopic agent decreases.

According to the phase diagram of FIG. 3, the reaction of heating decarboxylation reaction from calcium carbonate to calcium oxide in 1 atmosphere of carbon dioxide equilibrates at about 886 ° C. Therefore, even when heated to 650 ° C., almost no decarboxylation occurs. Therefore, even at the upper heating temperature of 650 ° C. for firing the shell, since the calcium carbonate nucleus is not decomposed, the primary firing step is performed by firing in an atmosphere of carbon dioxide partial pressure of 0.1 atm or higher. It is desirable to obtain a strength that does not shrink in the next secondary firing step.
The secondary firing step is performed following the primary firing step so that the pores of the shell are not blocked at a temperature lower than that of the primary firing. Firing in a vacuum atmosphere, or reducing the carbon dioxide partial pressure to 0.0001 atm or less, reducing the decarboxylation temperature to 500 ° C. or less, and decalcifying and pyrolyzing the calcium carbonate included in the shell to produce calcium oxide And At that time, carbon dioxide is released through the pores of the porous shell to form voids. The air gap takes various forms such as a hollow shape or a state in which a large number of holes are opened.

In the case of magnesium carbonate, decarboxylation is performed at a lower temperature than in the case of magnesium oxide. Since heating to 600 ° C. turns into magnesium oxide in the atmosphere, it is desirable that the primary firing is performed in carbon dioxide, the shell is fired while preventing decarboxylation, and the secondary firing is performed by a heat decarboxylation reaction in vacuum.
Here, the volume change upon thermal decomposition from 1 mol of CaCO ₃ (calcite, formula weight 100, density 2.71 g / cm ³ ) to CaO (formula weight 56.1, density 3.35 g / cm ³ ) is density. When calculated from the above, voids more than the same volume as CaO produced by volume shrinkage to 45% are generated in the shell.

In addition, CaO after firing changes mainly to Ca (OH) ₂ (formula weight 74.1, density 2.21 g / cm ³ ) after moisture absorption. At that time, after complete change, the volume expands by a factor of 2.0. Therefore, it can expand in the gap, and the volume expansion of the hygroscopic particles is suppressed.
The volume change upon pyrolysis from 1 mol of MgCO 3 (formula weight 84.3, 2.96 g / cm ³ ) to MgO (formula weight 40.3, 3.65 g / cm ³ ) is calculated to 39%. Volume shrinks. Moreover, MgO after baking changes mainly to Mg (OH) ₂ (density 2.21 g / cm ³ ) after moisture absorption. At that time, after the complete change, the volume expansion is 2.23 times in the calculation, occupying 87% of the volume inside the shell, and the volume expansion of the moisture absorbent particles is suppressed.

(Drying agent)
The obtained hygroscopic particles are kneaded into a low hygroscopic solid resin such as polytetrafluoroethylene and polyethylene so that the proportion becomes 10 to 90% by mass, more preferably 30 to 70% by mass. Can be processed into a sheet-like or film-like desiccant. If it is 10% by mass or less, the amount of moisture absorption is small, and if it is more than 90% by mass, the moisture absorbent particles may fall off. Alternatively, the obtained moisture absorbent particles can be kneaded into a liquid resin or monomer composition to form a liquid photosensitive or heat-sensitive adhesive or filler containing the moisture absorbent. The liquid resin is preferably a solventless liquid resin such as an epoxy resin, a urethane acrylate resin, a silicone resin, or a polyisobutylene resin.

For example, a urethane acrylate oligomer (20% by mass), an acrylic monomer (28% by mass), a hygroscopic agent (50% by mass) according to this embodiment, and a photopolymerization initiator (2% by mass) are kneaded and photocured with a hygroscopic agent. It can be a mold adhesive or a filler. In addition, the urethane acrylate oligomer can be replaced with an epoxy resin, and the acrylic monomer can be replaced with an epoxy monomer to further improve the adhesion to the substrate. Moreover, it can be set as a thermosetting adhesive and a filler by replacing a photoinitiator with a thermal polymerization initiator.
In order to enhance the dispersibility of the moisture absorbent particles in the resin, the surface of the moisture absorbent particles can be modified. For example, by reacting a fatty acid having a long chain alkyl group such as decanoic acid, lauric acid or stearic acid, or by refluxing in an alcohol such as ethanol, butanol, octanol, 2-methoxyethanol or diethylene glycol monomethyl ether, a hygroscopic agent The surface of the particles can be alkoxideized.

(Organic EL sheet)
The manufacturing process of an organic EL sheet is demonstrated using FIG.
The organic EL sheet 5 is formed by forming an organic EL element 7 on a substrate sheet 6 made of a transparent film or glass substrate, and adhering a sealing sheet 10 that protects the organic EL element 7 from deterioration due to moisture or the like with an adhesive resin 9. It is a flat light source that is covered and sealed, emits light with a DC voltage, does not generate noise, and is suitable for battery driving.
Although not shown, generally, in the configuration of the organic EL element 7, the anode, the hole injection transport layer, the organic light emitting layer, the electron transport layer, the electron injection layer, and the cathode are laminated on the substrate sheet 6 in this order. . Further, a passivation layer for moisture prevention is formed on the cathode as necessary. However, actually, the configuration of the organic EL element 7 is not limited to the above configuration.

As long as the light-emitting element emits light by energization using the organic light-emitting layer, other configurations and materials do not limit the present embodiment. Various light emission colors can be obtained as the organic EL light emission color by appropriately selecting an organic light emitting material in the light emitting layer.
Examples of the substrate sheet 6 made of an inorganic material include an alkali glass plate, a non-alkali glass plate, and sapphire glass having a thickness of about 0.05 mm to 1 mm.
Examples of the substrate sheet 6 made of a polymer include plastic sheets such as polyethylene terephthalate and polyethylene naphthalate of about 0.01 mm to 0.3 mm, epoxy resin, acrylic resin, cardo resin, and cyclic olefin resin, polymer films, and the like. .

In practice, the substrate sheet 6 made of the above polymer and the substrate sheet 6 made of the above inorganic material may be laminated.
Further, except for the case of wireless power feeding, an anode outlet and a cathode outlet are formed on the substrate sheet 6.
As the anode, a sputtering film or an ion plating film of a transparent conductive oxide material such as indium tin oxide (ITO) or indium zinc oxide (IZO) is appropriately patterned by etching, lift-off film formation, or mask film formation. be able to. In addition, polythiophene-based or polyaniline-based conductive polymers can also be used for the anode.

Note that an auxiliary electrode made of a metal mesh may be formed in contact with the anode for the purpose of lowering the resistivity of the anode or enhancing the in-plane light emission uniformity of the light emitting region. The organic EL sheet 5 on which the auxiliary electrode made of a metal mesh is disposed is less likely to concentrate current locally, and a highly uniform light emission luminance and temperature distribution can be obtained over the entire light emitting region of the organic EL sheet 5.
Each of the hole injection transport layer, the organic light emitting layer, and the electron transport layer is formed of one or more layers. Each of these layers can be formed by vapor deposition or application of a low molecular weight organic material or application of a polymer material.

The electron injection layer is formed between the electron transport layer and the cathode. For example, the electron injection layer easily emits electrons with a low work function composed of a simple substance or a compound containing alkali metal, alkaline earth metal such as lithium, calcium, barium, lithium fluoride, calcium oxide, and lithium quinoline, or rare earth. It consists of a material, or a material that is partially decomposed by reaction with the heat of vapor deposition or the cathode during cathode vapor deposition to form a low work function component.
As the cathode, a highly conductive aluminum or silver metal electrode is mainly used. When the cathode is made light transmissive and light is emitted from the cathode surface, or when light is emitted from both surfaces, the cathode metal layer is formed with a light transmissive thickness of about 10 nm or less, and a transparent conductive oxide layer is further formed. A light-transmitting cathode can be produced by laminating.

As the sealing sheet 10, a glass plate having a thickness of 1 mm or less, a plastic plate, a plastic film, a copper foil, an aluminum foil laminated sheet obtained by bonding a plastic film and an aluminum foil, or the like is used. It is bonded by an adhesive resin 9 such as an adhesive or an adhesive film having a low moisture permeability. Further, when a plastic sheet or a polymer film is used for the substrate sheet 6 or the sealing sheet 10, the organic EL sheet 5 having excellent flexibility (flexibility) can be realized.
Among the constituent materials of the organic EL element 7, the electron injection layer, which is a low work function material, and the metal material for the cathode are likely to react with moisture and deteriorate. However, when a plastic sheet or a polymer film is used for the substrate sheet 6 or the sealing sheet 10, the moisture permeability is higher than that of the inorganic glass, and the deterioration of the organic EL element 7 due to moisture is suppressed. It is desirable to use a sheet or film on which a water vapor barrier layer made of the above oxide is formed, and a multilayer laminated sheet obtained by superimposing them. Further, the desiccant according to the present embodiment is mixed in the adhesive resin used when these sheets and films are laminated and bonded together, and the moisture that reacts with the organic EL element 7 is removed from the adhesive resin and the sheets and films. It is effective.

(Synthesis example of hygroscopic particles)
A silica shell is baked by calcining particles having a diameter of about 100 nm formed by a sol-gel method with a shell of about 20 nm thick made of silicon oxide at the core of calcium carbonate at 600 ° C. for 30 minutes in carbon dioxide at 1 atm. I concluded.
Next, after stopping the supply of carbon dioxide and making a vacuum of 0.0001 atm or less, it is heated at 500 ° C. for 30 minutes to cause a decarboxylation reaction in the core of calcium carbonate and decompose, and converted to calcium oxide, Hygroscopic particles according to the present embodiment were obtained.

(Organic EL element configuration example 1)
This will be described with reference to the example of FIG. A silicon oxynitride film is laminated on both sides of a 20 μm thick polyethylene terephthalate film by CVD (chemical deposition) as a barrier layer and ITO film base, and an ITO (indium tin composite oxide) pattern is formed on one side. Was formed by sputtering to a thickness of 0.1 μm to obtain a transparent anode.
Next, an organic EL element 7 is formed on the anode by vacuum deposition, and an amorphous film of germanium oxide (GeO) that covers the entire cathode and sublimates at a low temperature as a passivation layer is formed by ion plating to 0.6 μm. . A passivation layer such as a GeO film or silicon nitride suppresses the transmission of moisture and monomers and absorbs ultraviolet to near ultraviolet rays. Therefore, the sealing sheet 10 is pasted on the organic EL element substrate sheet 8 with a photocurable adhesive resin 9. When attaching, the organic EL element 7 can be protected from photodegradation due to ultraviolet light or the like and dissolution of the organic layer due to penetration of the monomer of the adhesive. Further, as the adhesive resin 9, when the adhesive mixed with the moisture absorbent particles 4 according to the present embodiment synthesized in the above synthesis example is used, the moisture absorbent particles 4 are prevented from coming into contact and damaging the EL element surface. .

Finally, a urethane acrylate system containing 50% by mass of hygroscopic particles containing calcium oxide according to this embodiment synthesized as an adhesive resin 9 on the sealing sheet in which silicon oxide is vapor-deposited on both surfaces of a polyethylene terephthalate film. A photosensitive adhesive was applied, bonded to the organic EL element substrate sheet 8, and irradiated with 365 nm ultraviolet rays to be cured and bonded to obtain an organic EL sheet 5.
When the obtained organic EL sheet 5 is observed after being placed in an environment of 60 ° C. and a relative humidity of 90% for 100 hours, the swelling of the sealing end 11 is not recognized, and the distortion of the sheet and the deterioration of the organic EL element 7 are recognized. I couldn't.

(Comparative Example 1)
In the above “Organic EL element configuration example 1”, the organic EL sheet 5 is similarly used by using the adhesive resin 9 containing 50 mass% of calcium oxide particles having an average particle diameter of about 2 μm instead of the hygroscopic particles according to the present embodiment. Was made. When the obtained organic EL sheet 5 is observed after being placed in an environment of 60 ° C. and 90% relative humidity for 100 hours, the sealing end 11 swells due to moisture absorption of calcium oxide, and the distortion of the sheet and the deterioration of the organic EL element 7 occur. Admitted.

(Organic EL element configuration example 2)
Instead of the substrate sheet 6 of the organic EL sheet 5 prepared in the above “Organic EL element configuration example 1”, an organic EL sheet 5 was prepared using a substrate sheet having the following configuration.
This substrate sheet is a 38 μm thick single-sided lubricant coated polyethylene terephthalate film (Toyobo Cosmo Shine (registered trademark) A4300) with a non-lubricant coated smooth surface formed by CVD with a 0.5 μm silicon oxynitride film. A two-layer barrier film sheet 12, which is a urethane epoxy thermosetting composition in which 50% by mass of moisture absorbent particles containing calcium oxide according to the present embodiment are mixed on the CVD surface of the transparent barrier film sheet 12. An adhesive resin is applied, the lubricant coated surface of another transparent barrier film sheet 12 is bonded, heated to 120 ° C., heated and cured, and bonded.

FIG. 5 shows the configuration of the obtained organic EL sheet 5.
Next, the organic EL element 7 was formed on the CVD surface of this substrate sheet.
Finally, as the sealing sheet 10, an aluminum foil laminated PET sheet 15 in which a 12 μm polyethylene terephthalate (PET) film 14 is adhesively laminated on both surfaces of a 20 μm thick high-purity corrosion-resistant soft aluminum foil 13 is used. One-part heat-curing silicone adhesive resin mixed with 50% by mass of moisture absorbent particles containing calcium oxide was applied and bonded together, and sealed by heat curing at 120 ° C. instead of ultraviolet irradiation. Except for the above, an organic EL element 7 was produced in the same manner as in “Organic EL element configuration example 1”.
When the obtained organic EL sheet 5 is observed after being placed in an environment of 60 ° C. and a relative humidity of 90% for 500 hours, no swelling of the sealing end 11 is observed, and distortion of the sheet and deterioration of the organic EL element 7 are recognized. I can't.

(Effect of this embodiment)
According to this embodiment, there are the following effects.
The hygroscopic agent according to the present embodiment has a shell on the surface of the hygroscopic agent particles, and has a hygroscopic material containing a calcium or magnesium oxide and voids therein. When calcining calcium carbonate or magnesium carbonate into calcium oxide or magnesium oxide, the shell suppresses crystal growth due to sintering between the moisture absorbent particles, and can suppress a decrease in hygroscopic activity due to a decrease in specific surface area.

  The hygroscopic material in the hygroscopic agent according to the present embodiment reacts with water to absorb the moisture and expands in volume. However, the hygroscopic material can expand in the void surrounded by the shell, thereby suppressing the expansion of the hygroscopic agent itself. Therefore, long-term expansion | swelling of an adhesive dry sheet | seat can be suppressed, and the curvature and distortion of the organic EL sheet | seat by the difference in the expansion amount by peeling between board | substrates or a partial moisture absorption amount can be suppressed. Further, since moisture is absorbed through the porous shell having pores, the pore diameter and film thickness can be adjusted to moderately suppress the moisture absorption rate, and the moisture absorption ability can be maintained for a long period of time. In addition, it is possible to suppress the strong alkaline hydroxide generated after moisture absorption from coming into direct contact with the resin or the element, thereby suppressing the material deterioration of the organic EL element.

  Therefore, in the flexible organic EL sheet formed by bonding the organic EL element substrate formed on the flexible flexible substrate and the sealing substrate on which the barrier film or the like is laminated, the adhesive mixed with the moisture absorbent according to the present embodiment The organic EL element substrate sheet and the sealing sheet can be bonded and bonded together by heat or light irradiation using an adhesive dry sheet processed into a conductive resin or a sheet.

The hygroscopic agent according to the present embodiment and the desiccant using the hygroscopic agent can be applied to an organic EL sheet for display and illumination.
As mentioned above, although embodiment of this invention was explained in full detail, actually, it is not restricted to said embodiment, Even if there is a change of the range which does not deviate from the summary of this invention, it is included in this invention.

  DESCRIPTION OF SYMBOLS 1 ... Shell layer, 2 ... Hygroscopic material part, 3 ... Space | gap part, 4 ... Hygroscopic agent particle, 5 ... Organic EL sheet, 6 ... Substrate sheet, 7 ... Organic EL element, 8 ... Organic EL element substrate sheet, 9 ... Adhesion Resin, 10 ... Sealing sheet, 11 ... Sealed end, 12 ... Transparent barrier film sheet, 13 ... Aluminum foil, 14 ... PET film, 15 ... Aluminum foil laminated PET sheet

Claims (5)

A moisture-absorbing material part containing a metal oxide, and a moisture-permeable shell layer made of a porous oxide containing silicon,
The hygroscopic agent, wherein the shell layer surrounds the hygroscopic material portion and a void portion for expanding when the hygroscopic material portion undergoes a hygroscopic reaction.   A desiccant comprising a resin in which the hygroscopic agent according to claim 1 is kneaded. An organic EL sheet containing an organic EL element having an organic light emitting layer between at least a pair of counter electrodes,
The organic EL element is sandwiched between one or a plurality of sheets of a substrate sheet and a sealing sheet, and between the plurality of substrate sheets and the sealing sheet, or between the organic EL element and the sealing sheet. An organic EL sheet comprising the hygroscopic agent according to claim 1 at least.   A carbonate containing calcium or magnesium as a cation is used as a nucleus, and fine particles having a porous oxide film as a shell layer on the surface thereof are heated to a temperature of 300 ° C. or higher and 650 ° C. or lower to form a carbonate surrounded by the shell layer. A method for producing a hygroscopic agent, characterized in that a moisture absorbent material portion and a void portion are formed inside the shell layer by decarboxylating a salt nucleus and thermally decomposing it into an oxide.   Particles having a shell layer made of an oxide on the surface of carbonate crystal particles containing calcium or magnesium as a cation are calcined at a temperature of 500 ° C. or higher and 650 ° C. or lower in an atmosphere having a partial pressure of carbon dioxide of 0.1 or higher. Heating to a temperature of 300 ° C. or more and 500 ° C. or less in an atmosphere or a vacuum with a carbon partial pressure of 0.0001 atm or less to decarboxylate the carbonate particle portion surrounded by the shell layer and thermally decompose it into an oxide. A method for producing a hygroscopic agent.

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