JPH04277492A - Manufacture of el element - Google Patents

Abstract

PURPOSE:To provide an EL element having good characteristics by forming on a back plate a reflex insulation layer which is flat and smooth on the surface, is dense inside the layer, and contains Ba titanate as chief component. CONSTITUTION:A slurry as mixture of Ba titanate and one or more types of cyanoethyl series binders is applied onto a back plate and dried, and the obtained surface is pressed with a certain pressure to form a reflex insulation layer. Over this reflex insulation layer, a light emitting substance layer is formed.

Description

[Detailed description of the invention]

[Object of the invention]

0002

[Field of Industrial Application] The present invention relates to a method for manufacturing a distributed EL panel, and more particularly to a method for manufacturing an EL element in which a reflective insulating layer mainly made of barium titanate is formed on a back electrode. .

0003

[Prior Art] Dispersed EL elements have recently attracted attention as flexible surface light emitters that are lightweight, thin, and highly flexible in shape, and are widely used as backlights for liquid crystals and light sources for static elimination in dry copying machines. has been done.

This dispersion type EL element generally has a reflective insulating layer mainly made of barium titanate, which is known as a white inorganic dielectric material, and a fluorescent layer made of zinc sulfide or the like on a back electrode made of metal foil such as AL. It has a structure in which a luminescent layer made of body particles dispersed together with an organic fluorescent pigment in an organic dielectric material, and a transparent conductive film made of a plastic film with a transparent electrode formed on the contact surface with the luminescent layer are laminated in this order. A light-emitting phenomenon is caused by applying a required voltage between the back electrode and the transparent electrode.

[0005] Conventionally, in manufacturing such EL devices, a slurry of barium titanate mixed with an organic polymer having a high dielectric constant such as cyanoethyl pullulan or cyanoethylpoval has been prepared on a metal foil serving as a back electrode. A reflective insulating layer is formed by coating and drying a reflective insulating layer, and then a slurry mixture obtained by similarly mixing phosphor particles with an organic polymer is applied and dried to form a luminescent layer. After formation, a method is used in which a separately prepared transparent conductive film is laminated on the light emitting layer.

[0006]

[Problems to be Solved by the Invention] However, in such a method, the surface of the reflective insulating layer is not formed smoothly;
For this reason, the light emitting layer formed thereon is also not formed uniformly and smoothly, posing a problem in that it is difficult to obtain uniform light emission. Furthermore, since the interior of the reflective insulating layer is not dense, there is also the problem that electrical loss is likely to occur.

[0007] The present invention was made to solve these problems, and involves forming a reflective insulating layer mainly made of barium titanate, which has a dense interior and a smooth surface, on the back electrode. It is an object of the present invention to provide a method for manufacturing a high-quality EL element that can produce uniform light emission and have little electrical loss.

[Configuration of the invention]

[0009]

[Means for Solving the Problems] That is, the present invention provides a reflective insulating layer by coating a slurry mixture of barium titanate and one or more cyanoethylated binders on a back electrode and drying the mixture. In the method of manufacturing an EL device by forming a light emitter layer on the reflective insulating layer, the slurry-like mixture is applied onto the back electrode and dried, and then the surface is applied with a required pressure. It is characterized in that it is pressed and then a light emitting layer is formed thereon.

[0010] Examples of the cyanoethylated binder used in the present invention include cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, and cyanoethyl cellulose, which may be appropriately selected from these and used alone or in combination. be done.

In the present invention, one or more of the cyanoethylated binders described above are mixed with barium titanate, and a slurry-like mixture prepared by adding acetone or the like to an appropriate viscosity is applied to the back electrode, such as aluminum. After applying the required amount onto a metal foil such as and drying it, it is pressed directly or through a plastic film such as a silicone film using a press roller or the like. The press pressure at that time is 5 to 60 kg/cm2
A range of is appropriate. If the pressing pressure is too low, the smoothness of the layer surface will be insufficient, and if the pressing pressure is too high, the thickness of the layer may become thin, leading to a decrease in luminance. By pressing in this manner, the inside of the layer becomes dense and the surface is formed to be smooth. Note that the plastic film covered during pressing is removed after pressing.

0012

[Operation] In the method of the present invention, a slurry-like mixture made of barium titanate constituting the reflective insulating layer and one or more cyanoethylated binders is applied onto the back electrode and dried. By pressing the surface with the required pressure, the inside of the layer becomes dense and electrical loss is reduced. Further, since the layer surface is formed smoothly, the light emitter layer formed on this layer is also formed uniformly and smoothly, and uniform surface light emission can be obtained.

[0013]

EXAMPLES Examples of the method for manufacturing an EL element of the present invention will be described below.

First, 100g of barium titanate powder,
A mixture of cyanoethyl pullulan and cyanoethylcellulose in a weight ratio of 1:1 as a binder2
5g and 100g of each in a magnetic pot.
Milling was carried out for 24 hours together with alumina balls of mmφ and 20 mmφ. Next, this milled slurry of binder-containing barium titanate was adjusted to an appropriate viscosity by adding acetone, applied to the surface of a 50 μm thick aluminum foil, and dried at 100 °C for 30 minutes to remove titanate. A layer with a thickness of 30 to 70 μm mainly composed of barium was formed integrally. Thereafter, a 100 μm thick silicone film was placed thereon, and the surface was pressed with various pressures using a roller.

The inside of the cross section of the reflective insulating layer mainly made of barium titanate thus formed was examined using a scanning electron microscope (1000x magnification), and the reflective insulating layer formed in the same manner except for the pressing step was examined. When compared with the same microscope image of the inside of the cross section, it was found that barium titanate particles were densely present in all the pressed specimens, whereas there were gaps between the barium titanate particles in the unpressed specimens. confirmed.

[0016] Furthermore, the improvement rate (%) of the surface roughness due to each press pressure is expressed as R0, the surface roughness without pressing.
The surface roughness of the pressed material was calculated using the following formula as Rn. Improvement rate of surface roughness = (R0 - Rn) / R0 ×1
The 00(%) results are as shown in FIG. 1, and it was confirmed that the present invention improved the surface roughness, that is, improved the surface smoothness.

Subsequently, a luminescent slurry mixture in which zinc sulfide phosphor is dispersed in the binder and the viscosity is adjusted with acetone is applied onto the reflective insulating layer, and dried at 80° C. to emit light of 20 to 70 μm. A body layer is integrally formed, and an I.I. T. A transparent plastic film on which a transparent electrode made of O is formed is laminated with the transparent electrode and the light emitter layer facing each other, and then these are sandwiched between a transparent moisture-proof protective film and a nylon 6 film from both sides, and integrated by thermocompression bonding. An EL device was manufactured.

When the light emitting characteristics of the obtained EL devices were investigated, uniform and stable light emission was confirmed over the entire surface of each device.

[0019]

[Effects of the Invention] As explained above, according to the method of manufacturing an EL device of the present invention, it is possible to form a reflective insulating layer mainly made of barium titanate, which has a dense interior and a smooth surface. Therefore, it is possible to manufacture a high-quality, high-characteristic EL element with uniform light emission and low electrical loss.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the effect of improving surface roughness according to the present invention.

Claims (1)

[Claims] 1. A reflective insulating layer is formed by coating and drying a slurry-like mixture of barium titanate and one or more cyanoethylated binders on the back electrode, and then forming a reflective insulating layer on the back electrode. In a method for manufacturing an EL device by forming a luminescent layer thereon, the slurry-like mixture is applied onto the back electrode and dried, and then the surface is pressed with a required pressure, and then a luminescent layer is formed on the back electrode. A method for manufacturing an EL element, comprising forming a body layer.