JPH0765950A - Dispersion type el element - Google Patents

Abstract

PURPOSE:To provide a low-cost EL element of log lifetime by using a transparent anti-moistening material for a sealing/moistureproof film, wherein the material can be prepared at a low cost, presents flexural property, and is equipped with a moisture- proofness to the same degree as glass plate or PCTFE (ethylene tetrafluoride resin). CONSTITUTION:An insulative reflecting layer 9 and a light emitting layer 10 are formed on a base board 8 made from an aluminum sheet. By means of evaporation process, an admixture of indium oxide and tin oxide is laminated on a polyethylene terephthalate 15 to prepare a transparent electroconductive film 11, and silver paste is printed on the conductive side of this film 11, followed by a drying process to prepare a feeder wire 12, and thereto a lead electrode 13 consisting of phosphor bronz is attached. Then the light emitting layer 10 is overlapped on the printed surface of the feeder wire, followed by a hot press process using a roll laminator, and a lead electrode 14 is fixed to the base board 8 to serve as a back electrode, and thus the body of a light emitting element is completed. This body of light emitting element is pressure attached and sealed by roll laminator with a three-layer laminate film composed of polyethylene terephthalate 15, glass thin film 16, and low-density polyethylene 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersion type EL (electroluminescence) light emitting device using a laminated film of synthetic resin and glass as a moistureproof film for sealing.

[0002]

2. Description of the Related Art In recent years, EL light-emitting devices have been attracting attention as a uniform flat light-emitting body in which various shapes and light-emitting areas can be selected. Among them, the dispersion type EL light emitting device using a high dielectric organic binder is applied to a backlight light source of a liquid crystal display or an indicator light such as a night light because it is thin and lightweight and can be easily made large in area.

Such a dispersion type EL light emitting device is generally shown in FIG.
The structure is as shown in. That is, a back electrode 1 made of a metal foil or a thin metal plate, an insulating reflection layer 2 in which a high dielectric powder such as titanium oxide or barium titanate is dispersed in a high dielectric organic binder to form a thin film, and a phosphor powder. A phosphor layer (light emitting layer) 3 in which a thin film is formed by dispersing in a high dielectric organic binder, and a transparent electrode 5 formed by vapor deposition of a metal oxide such as indium oxide on an insulating film 4 such as polyethylene terephthalate or polyester.
(A transparent conductive film 6 is constituted by 4 and 5) is sealed with a transparent moisture-proof material 7 such as glass or synthetic resin, and the electrode 5 and the back electrode 1 are provided. The fluorescent substance is excited by applying an AC electric field between them and gives light emission.

Here, the life of the dispersion type EL light emitting device is influenced by moisture invading from the outside. This is because the transparent conductive film 6 usually has a moisture permeability of 20 g / m ² · 24 hr or more. Therefore, in order to protect the element from invading moisture, it is common to provide a moisture absorption layer and seal the outermost layer with the transparent moisture-proof material 7. That is, the life of the dispersion type EL light emitting element is determined by the moistureproof performance of the transparent moistureproof material 7 which is the above-mentioned sealing material.

Conventionally, as the transparent moisture-proof material, a glass plate is used as an inorganic substance, a trifluorochloroethylene resin (hereinafter abbreviated as "PCTFE") as a synthetic resin, and a polyvinylidene chloride resin as a synthetic resin.

However, when a glass plate is used, although the moisture resistance is satisfactory, the shape of the element itself is limited to a flat plate shape or is determined by the shape of the glass, and a free form depending on the place of installation can be used. Things that can't be taken,
It has drawbacks such as poor impact resistance and large weight.

On the other hand, when a synthetic resin is used, the advantages are that it can be sealed by a simple heat seal, it can take any shape depending on the shape of the element, and it has excellent impact resistance. However, it has the following drawbacks. That is, for example, when a polyvinylidene chloride resin is used, the moisture resistance is insufficient. Further, when PCTFE, which is currently the mainstream, is used, it is very expensive although it has excellent moisture resistance.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned drawbacks of the transparent moisture-proof materials that have been conventionally used, to have a moisture-proof property comparable to that of a glass plate or PCTFE, and to be inexpensive and flexible. It is to provide an inexpensive and long-life dispersion-type EL light-emitting element by using the transparent moisture-proof material which it has as a sealing moisture-proof film.

[0009]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors found that a film obtained by laminating a transparent glass thin film on a synthetic resin film is a moisture-proof film which is in principle equivalent to a glass plate. Paying attention to the fact that the dispersion type EL light-emitting element is sealed at the outermost layer using the PCTFE film as an encapsulating material at a lower cost than the element using the PCTFE film as an encapsulating material. Moreover, they have found that the same or longer life can be obtained, and completed the present invention.

That is, the present invention provides a structure in which an element body having a light emitting layer made of a dielectric material and an electroluminescent phosphor between a pair of electrodes, at least one of which is transparent, is sealed with a moisture-proof film. Further, the present invention relates to a dispersion-type EL light-emitting device, characterized in that the moisture-proof film is formed by laminating a transparent glass thin film on a synthetic resin film.

The present invention will be described in detail below. The synthetic resin film constituting the first layer of the sealing film used in the dispersion type EL light emitting device of the present invention has transparency and is 100 ° C.
Basically, the kind of the material is not limited as long as the shape can be stably maintained in the following temperature range, but for example, polypropylene, polyethylene, polyethylene terephthalate (hereinafter abbreviated as “PET”), polyvinylidene chloride,
Polyester etc. can be illustrated. Among them, PET and polyvinylidene chloride are particularly preferable.

The form of the synthetic resin film may be a single resin film, a film obtained by laminating a plurality of resins, or a stretched film or a non-stretched film. PCTFE film may be used although it is slightly expensive. However, for the purpose of use, it is desirable to use a resin having a moisture-proof property as high as possible. Further, it is also possible to mix an anti-UV agent or a pigment for performing color conversion of the dispersion type EL element. The thickness of the synthetic resin film is preferably about 10 to 200 μm.

The transparent glass thin film constituting the second layer is not particularly limited as long as it is transparent and has appropriate flexibility, but it is 10 to 500 nm on the synthetic resin film as the base material.
It is preferable that the glass layer is formed with a film thickness of about the same. The glass component may be either multi-component glass or quartz glass, but multi-component glass is preferable from the viewpoint of price and UV protection as long as the visible light transmittance is not extremely lowered.

As a method for laminating these two constituent elements, a vacuum vapor deposition method, an ion plating method, a sputtering method or the like can be used. Examples of these laminates and methods for producing the same include those disclosed in JP-B-3-6904, JP-A-2-249636, and JP-A-60-61255. By the above method, a glass thin film is formed and laminated on a synthetic resin which is a base material. At this time, it is preferable to bond a desired number of glass thin film laminated films by thermocompression bonding or an adhesive so that the order of the synthetic resin-glass thin film-synthetic resin-glass thin film is in order, if necessary.

To use this laminated film as a sealing film, in order to have heat sealability, 1) a hot melt adhesive layer is provided on the glass thin film surface, and 2) heat such as polyethylene is provided on the glass thin film surface. A method of thermocompression bonding synthetic resin with sealing property or laminating via a bonding agent,
3) A method of thermocompression bonding a glass synthetic resin or a process of laminating via a bonding agent and further providing a hot melt adhesive layer is required.

In order to manufacture a dispersion type EL light emitting device using this sealing film, a conventionally known method can be applied, and the conventionally used PCTFE film is changed to the sealing film according to the present invention. Just enough.

That is, first, a conventionally known binder such as an epoxy resin, a fluororesin, cyanoethyl pullulan, cyanoethyl cellulose, or a cyanoethylated compound such as cyanoethyl polyvinyl alcohol is used as a binder for a dispersion type EL element. Dissolve in a solvent such as formamide and disperse an inorganic dielectric material such as titanium oxide or barium titanate on the electrode substrate made of a material such as aluminum and gold, and dry it to 5 to 50 μm. An insulating reflection layer having a film thickness of is formed.

Then, on the insulating reflection layer, a dispersion liquid in which an electroluminescent phosphor such as ZnS is dispersed in a resin solution similar to the above is applied and dried to form thin film light emission having a film thickness of 10 to 50 μm. Form the layers.

Then, a transparent electrode is formed by applying a paste of tin oxide, indium oxide or the like and drying it, or by heat-pressing the conductive oxide vapor-deposited on an insulating film of polyester or the like. Form.

Finally, sealing is performed with the sealing film according to the present invention. At this time, for the purpose of the present invention, it is particularly preferable to use an existing phosphor whose surface is covered with a metal oxide or the like for moisture-proof treatment in order to prolong the life. A nylon layer may be laminated as a moisture absorption layer before sealing with a sealing film.

[0021]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples. The present invention is not limited to these.

Example 1 Cyanoethyl pullulan (manufactured by Shin-Etsu Chemical Co., Ltd .: CR-
S) and cyanoethyl polyvinyl alcohol (manufactured by Shin-Etsu Chemical Co., Ltd .: CR-V) were mixed at a ratio of 7: 3, and N,
N'-Dimethylformamide was added, mixed and stirred to prepare a uniform binder solution. 2 minutes into this solution,
To one of them, a phosphor powder having an average particle diameter of 30 μm (ZnS with Cu as an activator added) was added in an amount 3.2 times the binder weight and uniformly dispersed to obtain a light emitting paste. The other binder solution has an average particle size of 1.4 μm.
The barium titanate powder of was added in an amount of 4.7 times the weight of the binder and uniformly dispersed to prepare an insulating reflective layer paste.

Next, as shown in FIG. 2, the insulating reflection layer paste was printed and dried on the aluminum sheet substrate 8 having a thickness of 80 μm by a screen printing method to form an insulating reflection layer 9. Next, a light emitting layer paste was printed on the same layer by the screen printing method and dried to form the light emitting layer 10. The thickness of the obtained layer is about 26μ for the insulating reflective layer.
m, and the emission layer was about 58 μm.

On the other hand, a silver paste is printed and dried on the conductive surface side of a transparent conductive film 11 (Electrister 300c, manufactured by Nitto Denko Corporation), which is formed by vapor-depositing a mixture of indium oxide and tin oxide on polyethylene terephthalate. 12 is prepared, and a lead electrode 13 made of phosphor bronze
After mounting, the light emitting layer was superposed on the printed surface of the power supply line, and heat-pressed by a roll laminator. Then, the lead electrode 1 is formed on the aluminum sheet substrate 8 serving as the back electrode.
4 was attached to complete the light emitting element body.

Thereafter, the light emitting element body was pressure-bonded and sealed by a roll laminator with a three-layer laminated film consisting of polyethylene terephthalate 15 having a film thickness of 100 μm, glass thin film 16 having a film thickness of 200 nm and low density polyethylene 17 having a film thickness of 60 μm. A type EL light emitting device was obtained.

This device gives 72 cd / m ² at 100 V / 400 Hz driving, and a luminance half-life of 410 h at 100 V / 400 Hz driving in an atmosphere of 50 ° C. and 90% RH.
gave r.

Example 2 As shown in FIG. 3, a polyethylene terephthalate film 18 having a thickness of 30 μm was used as the first layer and a film thickness of 200 n was used as the second layer.
m glass thin film 19, a third layer having a thickness of 30 μm polyethylene terephthalate 18, and a fourth layer having a thickness of 200
nm glass thin film 19 and a moisture-proof film made of low-density polyethylene 20 having a film thickness of 50 μm as the fifth layer,
The same sealing as in Example 1 was performed to obtain a dispersion type EL light emitting device.

This device gives 69 cd / m ² at 100 V / 400 Hz drive, and a luminance half-life of 450 h at 100 V / 400 Hz drive in a 50 ° C. × 90% RH atmosphere.
gave r.

Comparative Example 1 A moisture-proof sheet (EL sealer 4) having a thickness of 250 μm and made of polychlorotrifluoroethylene as a sealing film.
810N-R, manufactured by Nitto Denko Corporation) was used, and a dispersion type EL light emitting device was produced in the same manner as in the example.

This device gives 68 cd / m ² at 100 V / 400 Hz drive and a luminance half-life of 370 h at 100 V / 400 Hz drive in an atmosphere of 50 ° C. and 90% RH.
gave r.

Comparative Example 2 A dispersion type EL light emitting device was produced in the same manner as in Example except that a package sheet made of polyethylene terephthalate having a film thickness of 200 μm was used as a sealing film.

This device gives 68 cd / m ² at 100 V / 400 Hz driving, and a luminance half-life of 80 hr at 100 V / 400 Hz driving in an atmosphere of 50 ° C. and 90% RH.
Was given.

As is clear from comparison between Examples 1 and 2 and Comparative Example 1, the light emitting device according to the present invention has a very expensive P
It has the same life as that using CTFE film.

[0034]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain a dispersion type EL light emitting device which has the same moisture resistance as a PCTFE film or a glass plate and has a long life and is inexpensive. This light emitting element can be widely applied as a planar light emitting body.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross section of a general structure of a light emitting device.

FIG. 2 is a diagram showing a cross section of a light emitting device of Example 1.

FIG. 3 is a diagram showing a cross section of a light emitting device of Example 2.

[Explanation of symbols]

 1 Back Electrode 2 Insulating Reflective Layer 3 Phosphor Layer (Light Emitting Layer) 4 Insulating Transparent Film 5 Transparent Electrode 6 Transparent Conductive Film 7 Transparent Moisture Proof Material 8 Aluminum Sheet Substrate (Back Electrode) 9 Insulating Reflective Layer 10 Light Emitting Layer 11 Transparent Conducting Film 12 Feed line 13 Lead electrode 14 Lead electrode 15 Polyethylene terephthalate 16 Glass thin plate 17 Polyethylene 18 Polyethylene terephthalate 19 Glass thin plate 20 Polyethylene (innermost layer)

Claims (1)

[Claims] 1. A dispersion-type EL light-emitting device in which a device body having a light-emitting layer containing a dielectric and an electroluminescent phosphor is sealed between a pair of electrodes, at least one of which is made of a transparent material, with a moisture-proof film. In the dispersion type EL light emitting device, the moisture-proof film is formed by laminating a synthetic resin film and a transparent glass thin film.