JPH0532875B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an EL device in which an EL element is sealed with a resin film.

BACKGROUND TECHNOLOGY AND PROBLEMS The EL device described above has been widely used as a very thin and flexible surface light source. FIG. 1 shows a conventional example of such an EL device. In this EL device 1, an EL element 2 having a substantially square thin plate shape is attached to two substantially square transparent resin films 3 having a larger area than the EL element 2.
The entire EL device 1 has flexibility.

The EL element 2 is a transparent polyester film 4
It has a transparent electrode 5 made of ITO vacuum deposited thereon. A slurry-like luminescent layer 6 is applied onto the transparent electrode 5 by screen printing to a thickness of 50 μm, and the luminescent layer 6 is dried by being kept at 150° C. for 30 minutes. On the light emitting layer 6, an Al foil is thermocompressed to a thickness of 100 μm using a hot roll at 180° C., and this Al foil serves as the back electrode 7 of the EL element 2.

The two resin films 3 sandwich the EL element 2 from the polyester film 4 and back electrode 7 side.
They are bonded together by thermocompression around the EL element 2. Since this thermocompression bonding is performed in dry Ar or N ₂ gas, the gap 8 between the two resin films 3 and the EL element 2 is sealed with this dry Ar or N ₂ gas.

The material used for the light-emitting layer 6 is a material in which phosphor particles are dispersed in cyanoethyl cellulose, which is a binder with a high dielectric constant, and the resin film 3 is a fluorohalocarbon film (for example, Allied, USA). Aclar (manufactured by Chemical Co., Ltd.) and polychlorotriproroethylene film are used.

Terminals (not shown) of leads (not shown) are attached to the electrodes 5 and 7 for connection to an external power source (not shown), and these leads are connected to two resin films. It extends from between 3 to the outside.

In the electrodes 5 and 7 of the EL device 1 configured as above,
When an alternating current voltage is applied through a lead (not shown), the light emitting layer 6 emits light. This light is extracted through the transparent electrode 5, the transparent polyester film 4, and the transparent resin film 3, and the EL device 1 is used as a surface light source.

Incidentally, although the resin film 3 has a certain degree of moisture resistance, it cannot completely block the permeation of moisture. For this reason, the moisture that has passed through the resin film 3 passes through the polyester film 4 and the transparent electrode 5 and reaches the light-emitting layer 6, and the light-emitting layer 6 is deteriorated by this moisture, and approximately 2000 hours after manufacture, the light-emitting layer 6 is deteriorated.
The brightness of EL device 1 was rapidly decreasing.

In order to prevent moisture that has passed through the resin film 3 from reaching the light-emitting layer 6, an EL device has conventionally provided a moisture absorbent with an average particle size of about 10 μm between the back electrode 7 and the resin film 3. It was hot. However, as mentioned above, the moisture that passed through the resin film 3 passed through the polyester film 4 and the transparent electrode 5 and reached the light emitting layer 6 rather than the back electrode 7. Even if a moisture absorbent was placed between the layers, deterioration of the light emitting layer 6 could not be effectively prevented.

It is also conceivable to arrange the above-mentioned moisture absorbent between the polyester film 4 and the resin film 3,
Since the average particle size of the hygroscopic agent is relatively large, about 10 μm, much of the light that should be extracted through the transparent electrode 5, polyester film 4, and resin film 3 is blocked by this hygroscopic agent. As a result, only an EL device 1 with low brightness can be obtained, which is not practical.

OBJECTS OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide an EL device that has a long lifespan despite almost no reduction in brightness and is easy to manufacture.

Summary of the Invention The present invention provides an EL element in which a light-emitting layer is sandwiched between a pair of electrodes, at least one of which is transparent, a resin film that seals the EL element, and a combination of the transparent electrode and the resin film. The present invention relates to an EL device characterized by having a coating layer disposed between the coating layers and containing ultrafine anhydrous silica particles.

Embodiment An embodiment of the present invention will be described below with reference to FIG.

As shown in FIG. 2, the EL device 1 according to this embodiment
1 is a polyester film 4 and a resin film 3
The structure is substantially the same as that of the conventional example shown in FIG. 1, except that a moisture absorbing layer 12 containing ultrafine anhydrous silica having an average particle size of 50 mm or less is arranged between the Good too.

The moisture absorption layer 12 is made of butyl carbitol (60% by weight) as a solvent and a transparent epoxy resin (40% by weight).
50 to 90% by weight of a binder consisting of
~10% by weight of ultrafine anhydrous silica (for example, AELOSIL manufactured by Nippon Aerosil Co., Ltd.) is dispersed therein. If the moisture absorbing layer 12 has such a composition, transmission of light will hardly be hindered.

In this embodiment, as shown in FIG. 2, a moisture absorption layer 12 is formed on a transparent polyester film 13.
A film coated in advance to a thickness of about 20 μm and dried in vacuum for 24 hours or more is placed between the polyester film 4 and the resin film 3.

In this way, since the moisture absorption layer 12 is arranged between the polyester film 4 and the resin film 3,
Moisture that has passed through the resin film 3 on the transparent electrode 5 side is adsorbed by the moisture absorption layer 12 and does not reach the light emitting layer 6. Therefore, the deterioration of the light emitting layer 6 due to moisture is extremely small, and the life of the EL device 11 is extremely long. Moreover, as described above, the moisture absorption layer 12 hardly prevents the transmission of light, so the light that should be extracted through the transparent electrode 5, the polyester film 4, and the resin film 3 is blocked by the moisture absorption layer 12. This moisture absorbing layer 12 allows the EL device 11 to
The brightness will not decrease.

Application Example The present invention has been described above based on one example.
The present invention is not limited to this example,
Various changes are possible.

For example, in the above embodiment, the film 13 for applying the moisture absorption layer 12 was made of transparent polyester, but the film 13 may be made of transparent nylon.

Further, in the above embodiment, the moisture absorption layer 12 was applied to the polyester film 13, but this moisture absorption layer 12 is directly applied to the side of the polyester film 4 opposite to the transparent electrode 5, and the polyester film 13 is not used. You can also do it like this.

Furthermore, in the above embodiment, since the EL element 2 is single-sided light emitting, the transparent electrode 5 is provided.
Although the moisture absorption layer 12 was arranged only on one side of the EL element 2,
In the case of a double-sided emitting EL element, the EL element may have a structure in which moisture absorbing layers 12 are disposed on both sides of the EL element.

Further, in the above embodiment, the moisture absorbing layer 12 was disposed only on the transparent electrode 5 side of the EL element 2, but the moisture absorbing layer 12 may also be disposed between the back electrode 7 and the resin film 3. In this case, the life of the EL device 11 can be made longer.

Further, in the above embodiment, when manufacturing the EL element 2, Al foil was thermocompression bonded to a thickness of 100 μm on the light emitting layer 6, but Al may be vacuum-deposited to a thickness of 5000 Å. Conversely, the light emitting layer 6 may be formed by coating it on Al foil.

Effects of the Invention As described above, in the EL device according to the present invention,
A coating layer containing ultrafine anhydrous silica particles is disposed between at least the transparent electrode and the resin film for sealing the EL element.

Therefore, the water that has passed through the resin film on the transparent electrode side is adsorbed by the ultrafine anhydrous silica particles and does not reach the light emitting layer of the EL element. Therefore, deterioration of the light emitting layer due to moisture is prevented, and an EL device with a long life can be provided. Moreover, since the anhydrous silica is ultrafine particles, the transmission of light is hardly hindered, and the life of the EL device can be extended without substantially reducing the brightness of the EL device.

Furthermore, since the ultrafine anhydrous silica particles are contained in the coating layer, the coating layer can be easily formed even over a wide area, making it easy to manufacture the EL device.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing a conventional example of the present invention, and FIG. 2 is a schematic sectional view showing an embodiment of the present invention. In addition, in the symbols used in the drawings, 2...
...EL element, 3...Resin film, 5...Transparent electrode, 6...Light emitting layer, 7...Back electrode, 11...
EL device, 12...moisture absorption layer.

Claims (1)

[Claims] 1. An EL element in which a light emitting layer is sandwiched between a pair of electrodes, at least one of which is transparent; a resin film that seals this EL element; and a combination of the transparent electrode and the resin film. An EL device characterized by having a coating layer disposed between the coating layer and containing ultrafine anhydrous silica particles.