JPS593840B2 - Manufacturing method of EL light emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distributed electroluminescent device that emits light by applying an electric field to phosphor powder.

It is widely known that when an electric field is applied to a phosphor powder such as ZnS in which manganese is diffused, the phosphor powder emits light. A device, an electroluminescent device, has been developed.

However, conventional electroluminescent devices have various problems, and only a few have been put into practical use. FIG. 1 is a diagram showing the basic structure of an electroluminescent device. 1 is a transparent electrode formed on one surface of a transparent insulating substrate 2 such as a glass substrate or a plastic film substrate, and has a sheet resistance of several Ω. /□It is made of a thin film such as In02 or sno2, or a metal thin film such as gold or palladium, or aluminum foil with small mesh-like holes. 3 is the other counter electrode, which is one in which metal powder such as silver is dispersed in an organic polymer or inorganic binder, or one in which a metal plate such as aluminum or copper is pasted. It is. A typical electric field transmissive device uses a phosphor powder made of ZnS doped with an activator such as copper or manganese, and an activator such as chlorine, between the transparent electrode 1 and the counter electrode 3 that face each other. , 30, a light-emitting layer 4 dispersed in an organic polymer binder, and TiO2 or BaT.
A structure in which an insulating layer 5 in which high dielectric constant powder such as i03 is dispersed in an organic polymer binder is sandwiched, and the entire structure is covered with a moisture-proof protective film 6 made of trifluorochloroethylene, epoxy resin, etc. It is becoming. 35 Note that rare earth elements, monovalent metals, transition metals, etc. are used as the phosphor powder.

In FIG. 1, when an alternating current voltage is applied between both electrodes 1 and 3, an electric field corresponding to the voltage and frequency is applied to the light emitting layer 4, which emits light. In order to increase the emission intensity, (a) increase the applied voltage; The thickness of the light emitting layer 4 and the insulating layer 5 is reduced.

(c) Used for light emitting layer 4 and insulating layer 5? Use a high dielectric constant organic polymer binder. (b) Increase the frequency of alternating current.

etc.

However, there is a limit to increasing the voltage or making the light emitting layer 4 and the insulating layer thinner, as this may cause dielectric breakdown between the electrodes 1 and 3.Also, increasing the AC frequency To do this, it is necessary to prepare a separate power source, and if the frequency is changed, the emission wavelength will also differ.Therefore, in order to increase the luminance without reducing the characteristics of the electroluminescent device, it is necessary to It is sufficient to use a material with a high dielectric constant as the organic polymer binder used in layer 5.However, the cyanoethylated cellulose and epoxy resin that have been conventionally used as the organic polymer binder have the following properties. In other words, cyanoethylated cellulose has a high dielectric constant, but has weak film adhesion, and also has poor heat resistance and moisture resistance. Epoxy resins also have poor heat resistance and moisture resistance. The phosphor powder used in electroluminescent devices decomposes within a very short time when a voltage is applied in a humid state. Since it has the weakness of losing its light-emitting function, even when covered with a moisture-proof protective film 6, conventional electroluminescent devices are sensitive to humidity, have a short lifespan, and are unreliable.

In order to eliminate the above-mentioned drawbacks, the inventor filed a previous application (patent application filed in 1973).
5-38423), the organic polymer binder used in the light emitting layer 4 and the insulating layer 5 is a copolymer of vinylidene fluoride and propylene hexafluoride to which a vulcanizing agent is added. I mentioned that I got good results. The copolymer of vinylidene fluoride and propylene hexafluoride is commonly called fluorocarbon rubber, is flexible, and has a dielectric constant of 15 (
60Hz), has strong adhesive strength, and has the best heat resistance and moisture resistance among other rubbers.

In this way, as the organic polymer binder used in the light-emitting layer 4 and the insulating layer 5, a copolymer of vinylidene fluoride and propylene hexafluoride, which has excellent properties, and a vulcanizing agent are used. The resulting electroluminescent device has excellent heat resistance and moisture resistance, high luminance, long life, and high reliability. The present invention has been made in order to provide a method for manufacturing a highly reliable EL light emitting device with good moisture resistance.

Hereinafter, the present invention will be explained based on an example and with reference to FIG.

Example 1 First, raw rubber, which is a copolymer of vinylidene fluoride and propylene hexafluoride, is dissolved in an organic solvent such as acetone or methyl ethyl ketone to prepare a 25Cf1) solution (this is used as a prisoner).

Next, vulcanizing agents such as amines, polyols, and peroxides are dissolved in an organic solvent to prepare a 2% solution (this will be referred to as "B"). These solutions and phosphor powder are mixed at a mixing ratio of A:B:phosphor powder=4:1:7 to create a phosphor paste. Next, on a transparent substrate 2 such as a glass substrate,
Formed by etching method, screen printing method, etc.
A phosphor is applied onto a transparent electrode 1 made of a thin film of InO2, snO2, etc., a metal thin film such as gold, or an aluminum foil with small mesh holes, by spraying, coating, screen printing, etc. Apply the paste and heat at 70℃ for 15 minutes.
After drying for minutes, a dense unvulcanized luminescent layer 20-30 microns thick is formed. On the other hand, an insulating paste made by mixing liquid A, liquid B, and TiO2 at a mixing ratio of 4:1:1.5, respectively,
Coated on the counter electrode 3 made of a metal plate such as At or 0u,
Dry at 70°C for 15 minutes to form an unvulcanized insulating layer approximately 20μ thick.

Vulcanization is performed at 150° C. for 4 hours while the partially vulcanized light-emitting layer and unvulcanized insulating layer are placed facing each other and pressed together. By vulcanization, both layers. Adhesion with sufficient strength required for EL light emitting devices is obtained, and does not peel off due to reheating or organic solvents. Finally, the entire structure is covered with a moisture-proof protective film 6 made of trifluorochloroethylene, epoxy resin, or the like to complete the EL light emitting device. Both electrodes 1 of the EL light emitting device created in this way
When an alternating voltage of 100 and 50 Hz is applied between .
50Hz heat resistance load test and 40℃, 90-950t)
RHMJOOV was subjected to a 50Hz humidity load test, but
The brightness half-life is 1000H under heat-resistant load and 2.0H under humidity-resistant load.
At 500H, a product with particularly good moisture resistance was obtained. Example 2 In the same manner as in Example 1, a phosphor paste is applied onto the transparent electrode 1 and then oven-vulcanized at 150° C. for 4 hours to form the light-emitting layer 4.

Further, on the light emitting layer 4, an insulating paste containing no vulcanizing agent, which is a mixture of the liquid A and TiO2 at a mixing ratio of 4:1.5, is applied and dried. form an insulating layer that does not contain On the other hand, the liquid B is applied onto the counter electrode 3 made of a metal plate such as At or Cu and dried to form a vulcanizing agent layer. The vulcanizing agent layer and the insulating layer not containing the vulcanizing agent are placed facing each other and vulcanized at 150° C. for 4 hours while being crimped, and then the whole is covered with a moisture-proof protective film 6 such as ethylene trifluoride chloride. Complete the YEL light emitting device. The completed EL light emitting device had the same performance as Example 1. Example 3 In the same manner as in Example 1, an insulating paste is applied onto the counter electrode 3 and then oven-vulcanized at 150° C. for 4 hours to form the insulating layer 5.

Further, on the insulating layer 5, the above-mentioned liquid A and phosphor powder are mixed at a mixing ratio of 4:1.5, and a phosphor paste containing no vulcanizing agent is applied and dried. Form a light emitting layer. On the other hand, the liquid B is applied and dried on the transparent electrode 1 to form a vulcanizing agent layer. The vulcanizing agent layer and the emitting layer not containing the vulcanizing agent were placed facing each other and heated at 150° C. for 4 hours while being pressed together.
After vulcanization for a period of time, the entire body is covered with a moisture-proof protective film 6 made of trifluorochloroethylene or the like to complete the EL light emitting device. The completed EL light emitting device had the same good performance as Example 1. As described above, the present invention has the great advantage of providing an EL light emitting device with particularly excellent moisture resistance and reliability.

[Brief explanation of drawings]

FIG. 1 is a partially enlarged side sectional view of a general electroluminescent device, showing the basic configuration of the electroluminescent device. DESCRIPTION OF SYMBOLS 1...Transparent electrode, 2...Transparent insulating substrate, 3...Counter electrode, 4...Light emitting layer, 5...Insulating layer, 6...Moisture-proof protective film.

Claims (1)

[Scope of Claims] 1. A transparent electrode, a light emitting layer in which phosphor powder is dispersed in a copolymer of vinylidene fluoride and propylene hexafluoride, and a light emitting layer in which phosphor powder is dispersed in a copolymer of vinylidene fluoride and propylene hexafluoride. The insulating layer in which ferroelectric powder is dispersed, the counter electrode, and a thin layer of vulcanizing agent provided between the transparent electrode and the light emitting layer or between the insulating layer and the counter electrode are brought into close contact and heated under pressure. A method for manufacturing an EL light emitting device, characterized in that: 2 An insulating layer in which ferroelectric powder is dispersed in a copolymer of vulcanized vinylidene fluoride and propylene hexafluoride provided on the counter electrode, and a fluorine containing no vulcanizing agent provided on the insulating layer. A light-emitting layer made of a copolymer of vinylidene chloride and propylene hexafluoride with phosphor powder dispersed in it, and a transparent electrode coated with a thin layer of vulcanizing agent on the surface are brought into close contact and heated under pressure. A method for manufacturing an EL light emitting device according to claim 1. 3 A light-emitting layer in which phosphor powder is dispersed in a copolymer of vulcanized vinylidene fluoride and propylene hexafluoride provided on a transparent electrode, and a vinylidene fluoride layer not containing a vulcanizing agent provided on the light-emitting layer. A patent characterized in that an insulating layer made of a copolymer of ferroelectric powder dispersed in a copolymer of propylene hexafluoride and a counter electrode coated with a thin layer of a vulcanizing agent are brought into close contact with each other and heated under pressure. A method for manufacturing an EL light emitting device according to claim 1.