JPS5880295A - Method of producing el element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a distributed EL element.

Distributed EL elements are planar light sources that can emit light in various colors with low power consumption, and are low cost and easy to manufacture over a large area, so they are expected to be applied to various display devices and displays. However, the reason why it has not yet been put into practical use as a bed desk is because the brightness and blue gold have not reached a practical level, and there is a strong demand for improvement.

As is well known, dispersion type ELs can be roughly divided into sintered type and resin type in terms of the light-emitting layer and electric material, and the one in the present invention belongs to the latter. An example of a conventional method for producing this type of EL device is to form a light-emitting layer consisting of an organic dielectric and an electroluminescent phosphor on a transparent conductive glass plate, and then to form a light-emitting layer on the layer. A high-permittivity reflective layer made of barium titanate powder and a dielectric is formed, then a back electrode is formed on the reflective layer by aluminum vacuum evaporation, and a moisture-proof glass plate is then bonded for moisture-proof sealing. I was stopping.

Due to the properties of currently used ZnS-based phosphors, the brightness of this type of EL element increases in proportion to the 2nd to 5th power of the applied electric field strength. Brightness can be improved by applying as large an electric field strength as possible to the light particles. One way to achieve this is to make the dielectric constant of the dielectric in which the fluorescent material is embedded sufficiently larger than that of the fluorescent particles, and the dielectric constant of the fluorescent particles is 15 to 20.
Therefore, it is thought that it is necessary to improve the dielectric constant of the dielectric material to about 60. On the other hand, the dielectric constant of organic materials with normal film forming properties is 10 or less, and it is necessary to improve the dielectric constant of the dielectric material to about 60. Even for quanoethylated cellulose and cyanoethylated PVA, the value is about 13 to 20, which is below the ideal value.
Most of the organic substances with an m-durability of 20 or more are liquid or semi-liquid, and by blending them with the above-mentioned high dielectric constant resin that has film-forming properties, it was possible to improve the brightness to some extent ΦIn this case. As the amount of the high dielectric constant liquid increases, the dielectric constant of the dielectric mixture increases and the brightness of the EL element increases, but as the amount of the high dielectric constant liquid increases, the surface strength of the light emitting layer decreases. However, there was a problem in that it was difficult to form a back electrode on this film surface by aluminum vacuum evaporation. Furthermore, even if the back electrode can be formed, when the moisture-proof glass plate is bonded and sealed with adhesive in the next moisture-proofing process, there is a risk that the light-emitting surface will be disturbed due to the stress caused by the adhesive curing. However, increasing the blending ratio of high dielectric constant liquids such as cyanethylated polyols has had many problems in terms of manufacturing.

The purpose of the present invention is to eliminate the problems of the prior art described above and to improve the brightness by creating a rational method suitable for blending a high dielectric constant liquid such as cyanoethylated polyols in a high ratio in a dielectric material constituting a light emitting layer. The object of the present invention is to provide a method for manufacturing an EL element at low cost.

The 41 features of the EL device manufacturing method of the present invention are as follows:
Between the transparent substrate having a transparent conductive layer and the conductive substrate facing the skin, a light emitting layer on the transparent substrate side and a high dielectric constant reflective layer on the conductive substrate side are formed. a first step of bonding the peripheral edge and the peripheral edge of the conductive substrate with an adhesive peripheral edge made of a thermosetting resin, leaving the injection port;
After the first step of wiring, a high dielectric constant liquid to which a gelling agent has been added is poured in a vacuum heating and drying atmosphere through the injection port into the area surrounded by the adhesive periphery between the transparent substrate and the conductive substrate. The method includes two steps: a second step of injecting the cell into the cell to fill the cell so that no air bubbles remain, and then closing the injection port. Here, the light-emitting layer is composed of a dielectric material and an electroluminescent fluorescent material, and can be formed by, for example, printing, and the high dielectric constant liquid l- is preferably made of powder of thurium mititanate. The conductive substrate is preferably an aluminum plate, the thermosetting resin is preferably a thermosetting epoxy resin, and the preferred high dielectric constant liquid is cyanoethylated. According to the method of the present invention, high dielectric materials such as cyanoethylated polyols, which could not be applied in the prior art, can be used to block the injection port. A preferable example of the first step in the method for manufacturing an EL device of the present invention is as follows. It is as follows.

A high permittivity dielectric material and an electroluminescent ZnS phosphor are coated on the conductive layer side of a transparent substrate having a transparent conductive layer, for example, a commonly known Nesa glass plate or an EC glass plate, by a screen printing method or a spray method. A light-emitting layer is formed and subsequently barium titanate powder and high dielectric II! are applied on the layer in the same manner. A high dielectric constant reflective layer made of a constant dielectric material is formed. The high-permittivity dielectric material used for both layers contains a large amount of high-permittivity cyanethylated polyols, and has low mechanical strength, making it difficult to form a back electrode by vacuum vapor deposition of aluminum, etc. It is something. Next, as a conductive substrate that serves as a back electrode and a moisture-proof sealing plate, for example, an aluminum plate is pressed onto the film-forming surface in a reduced-pressure heating and drying atmosphere, and the peripheral edges thereof are heated and hardened. At this time, an injection port is provided at the adhesive periphery for injecting a high dielectric constant liquid into the cell in the next step. This completes the first step.

In another preferred example of the first step in the method for manufacturing an EL element of the present invention, a light emitting layer similar to that in the above example is formed on the transparent conductive layer of a transparent substrate having a transparent conductive layer; A high dielectric constant reflective layer similar to that in the above example was formed on a conductive substrate made of an aluminum plate, and a light emitting layer and a high dielectric constant reflective layer were stacked on top of each other in the same manner as in the above example. , in a vacuum heating and drying atmosphere, the conductive substrate is pressed against the transparent substrate, the light emitting layer and the high dielectric constant reflective layer are pasted together, and the periphery is bonded with a heat curing adhesive.The periphery is bonded to the transparent substrate and conductive. At the same time, in the next step,
A good process is to provide an injection port for injecting a high dielectric constant liquid into the cell.

A preferred example of the second step performed on the product after the first step is completed as described above is as follows.

In contrast to step 4 after the completion of the first step, a high dielectric constant substance that exhibits fluidity when heated and solidifies when cooled to room temperature, such as a high dielectric constant liquid containing a gelling agent, is heated in a vacuum heating drying atmosphere. Inject and fill the cell from the injection port so that no air bubbles remain, and then close the injection port with a heat-curing adhesive.
The second step is completed.

Below, the present invention will be explained in more detail by way of example and with reference to the drawings.

Example-1 Cyanoethylated PVA 1 part by weight Cyanoethylated sorbitol 9 parts by weight Electroluminescent ZnS phosphor 30i! Part f: An appropriate amount of an organic solvent 2N-methyl-2-pyrrolidone was added to the above mixture and thoroughly kneaded to prepare a printing paste for a light-emitting layer.

In the same manner, 1 part by weight of cyanoethylated PVA 9 parts by weight of cyanoethylated sorbitol 80 parts by weight of barium titanate powder
-An appropriate amount of methyl-2-pyrrolidone was added and thoroughly kneaded to prepare a paste for a high dielectric constant reflective layer.

Next, as shown in FIG. 1(A), on the transparent conductive layer 2 of the transparent base jtji1 having the transparent conductive layer 2, the above printing paste for a light emitting layer is printed by a screen printing method, and the first
A light-emitting layer as shown by reference numeral 3 in Figure (B) was formed to have a film thickness of 60 to 35 μm after drying.

Subsequently, the above-mentioned paste for a high dielectric constant reflective layer was printed on the light emitting layer 6 to form a film having a thickness of 10 to 5 μm after drying. Figure 1 (0) shows this state.
The reference numeral 4 is a high dielectric constant reflective layer. Accordingly, the total thickness of the light emitting layer and the high dielectric constant reflective layer is 35 to 45 μm.

Next, a conductive substrate 5 made of an aluminum plate having a thickness of 0.3 to 0.5 mm is placed on the high dielectric constant reflective layer 4 in a heated and dry atmosphere under reduced pressure, and its dimensions and shape 9 are placed. With the position corresponding to the transparent substrate 1 as shown in FIG.
While the substrates were pressed together, a thermosetting epoxy resin was infiltrated into the peripheral edges of both substrates 1.5, leaving an injection port 7, to form an adhesive peripheral edge 6 for bonding the peripheral edges of both substrates. . This state is shown in FIG. 1(E) and FIG. 2, which is a sectional view taken along the dashed line xx in FIG. 1(E). For this,
A cell structure surrounded by the adhesive periphery 6 is formed between the two difference plates, and the first step is completed.

Next, move on to the second step.

About 5 g of the gelling agent dibenzylidene-D-sorbitol was added to the structure formed as described above through the injection port 7 in a vacuum heating and drying atmosphere. Next, the injection port 7 was cleaned with acetone and sealed by applying an epoxy resin adhesive.This is the second step. Marked as completed 0 The EL layer produced as described above has a high proportion of cyanethylated polyols added to its emissive layer material, but at room temperature the emissive layer material exhibits a solid state. Lights up continuously for a long time.

However, no abnormality such as disturbance of the light emitting surface was observed.
50H2100V Te5~8 ft-L (7) It has a brightness of 5 to 8 ft-L, and the brightness half-life time when continuously lit at room temperature is 400
0 hours or more, and was sufficiently usable for 20,000 hours.0 Example 2 A light-emitting layer was formed on the transparent conductive layer of a transparent substrate having a transparent conductive layer using the same method and material as in Example 1. did.

On the other hand, on a conductive substrate made of an aluminum plate with a thickness of approximately 0.5 mm, a high dielectric constant reflective layer was formed using the same high dielectric constant reflective layer material as in Example 1 and by the same formation method. .

Next, in a vacuum heating and drying atmosphere, the above-mentioned two substrates are pasted together so that the light-emitting layer and the high dielectric constant reflective layer are in contact with each other, and they are heat-pressed using a jig, and the peripheral edge of the substrate is bonded with the injection port. An adhesive periphery of a thermosetting epoxy resin was formed in a manner similar to that described above, and the peripheries of both substrates were bonded together. The state is the first
A structure was formed as shown in FIG.

Next, cyanoethylated mannitol containing about 5% of the gelling agent dibenzylidene-D-sorbitol is injected into the above-mentioned structure from the injection port in a vacuum heat-drying atmosphere to impregnate it without leaving any air bubbles. It was filled into the cell in this way.

Next, the injection port was cleaned with acetone and then closed and sealed using an epoxy resin adhesive.

The EL 4 element according to this example produced in this way had higher luminance and longer life than the conventional one, similar to the one in Example 1. As described above, the present invention According to the manufacturing method according to 1) it becomes possible to use a material containing a high dielectric constant liquid, cyanethylated polyol, in a high proportion in the light-emitting layer material of an EL device, and even if the same phosphor is used, it is possible to use a material containing a high proportion of cyanethylated polyols. 2) The conventional process of forming a back electrode using the aluminum vacuum evaporation method can be omitted;
It also has advantages in terms of cost; 3) Since the back electrode plate also serves as a moisture-proof sealing plate, the conventional moisture-proof sealing process can be omitted; EL elements with excellent brightness and longevity can now be obtained more rationally and at lower cost than with conventional methods, paving the way for the practical application of distributed EL elements in the future. .

[Brief explanation of drawings]

Figure 1 (4) + (B) - (C) +Φ), (R1)
2 is a vertical cross-sectional view of the approximately central part parallel to one side of the device, showing the sequence in the first step of an embodiment of the method for manufacturing an EL device of the present invention, and FIG. It is a longitudinal cross-sectional view taken along the x-X line. 1...Transparent substrate 2...Transparent conductive layer 3...9
Light-emitting layer 4... High dielectric constant reflective layer 5... Conductive substrate 6... Peripheral portion 7... Inlet portion attorney patent attorney Thin 1) Interest t

Claims (7)

[Claims] (1) A light emitting layer on the transparent substrate side and a high dielectric constant reflective layer on the conductive substrate side are formed between a transparent substrate having a transparent conductive layer and a conductive substrate facing the transparent conductive layer, and After the first step of adhering the peripheral edge and the peripheral edge of the conductive substrate with the adhesive peripheral edge made of a thermosetting resin, leaving the injection port, the gel is bonded in a vacuum heating and drying atmosphere. A high dielectric constant liquid to which a curing agent has been added is injected into the cell surrounded by the adhesive periphery between the transparent substrate and the conductive substrate through the injection port, and is filled so that no air bubbles remain. ,#
□ A method for manufacturing an EL device, comprising the steps of: □ a first step and a second step of closing an injection port; (2) In the first step, a transparent conductive layer is formed on the transparent conductive layer of the transparent substrate, except for the peripheral part, and a high dielectric constant reflective layer is formed on the polarizing angle optical layer. A conductive substrate corresponding to the transparent substrate is placed on the reflective layer, and the conductive substrate is bonded to the high dielectric constant reflective layer in a vacuum heating and drying atmosphere. Manufacturing the EL element according to claim 1, wherein the periphery between the conductive substrates is bonded to an adhesive periphery made of a thermosetting resin, leaving an injection port. Method. (3) In the first step, a light-emitting layer is formed on a transparent substrate having a transparent conductive layer except for the upper peripheral edge of the transparent conductive layer, and the upper peripheral edge of the conductive substrate corresponding to the transparent substrate is formed. A high dielectric constant reflective layer is formed on the removed portion, and the light emitting layer and the high dielectric constant reflective layer are bonded together in a vacuum heating and drying atmosphere and pressure bonded to the transparent substrate and the conductive substrate. 8. A method for manufacturing an EL element according to claim 1, which comprises bonding the peripheral edges between the transparent substrates with an adhesive peripheral edge made of a thermosetting resin, leaving an injection port. (4) The light-emitting layer is formed of a dielectric material and an electroluminescent phosphor by, for example, printing or the like. A method for manufacturing an EL device according to the above. (5) The EL according to any one of claims 1 to 4, wherein the high dielectric constant reflective layer contains a white high dielectric constant powder such as barium titanate powder.
Method of manufacturing elements. (6) The method for manufacturing an EL element according to any one of claims 1 to 5, wherein the conductive substrate is made of an aluminum plate. (7) The method for manufacturing an EL element according to any one of claims 1 to 6, wherein the thermosetting resin is a thermosetting epoxy resin. (8) The high dielectric constant liquid is Method for manufacturing an EL device according to any one of claims 1 to 7, which is a cyanethylated polyol (9) The injection port is closed with a heating adhesive. 9. The method for manufacturing an EL element according to any one of claims 1 to 8, wherein the EL element is group-closing.