JPH04264389A - Electroluminescent(el) panel and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain EL panel, of which luminance deviation with aged change to be caused by moisture is improved remarkably, by raising moisture-proofing property thereof without hindering conventional flexibility, and obtain manufacture of EL panel formed with glassy transparent thin film by low temperature drying treatment at a temperature less than 100 deg.C without hindering organic material. CONSTITUTION:In EL panel, metal alkoxide solution is adhered to the surface of a light emitting substrate 2, and it is dried at a temperature less than 100 deg.C, and thereafter, low temperature plasma treatment is performed to form transparent thin film 4 on the whole surface of the light emitting substrate 2. In manufacture, a light emitting substrate 2 is coated with metal alkoxide solution, and it is dried at a temperature less than 100 deg.C, and thereafter, low temperature plasma treatment is performed, and the transparent thin film 4 is thereby formed over the whole surface of the light emitting substrate 2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an EL (electroluminescent) panel, and more particularly to a method for manufacturing an EL panel with a strengthened moisture barrier layer using a novel method.

[
0002

[Prior Art] Generally, a dispersed EL panel is manufactured by coating a back electrode such as aluminum foil with a white high dielectric constant powder such as BaTiO3 dispersed in a high dielectric constant organic solution such as cyanoethyl cellulose, and then drying it. A reflective insulating layer is formed on the reflective insulating layer, and a luminescent layer is formed by dispersing a phosphor powder such as ZnS:Cu in a solution of a high dielectric constant organic material such as cyanoethyl cellulose and drying. A transparent electrode made by laminating a transparent conductive material such as In2O3 on one side of the base is laminated on the light emitting layer, a current collection band is formed on the periphery of the transparent electrode, and a voltage application lead is connected from this current collection band and the back electrode. After pulling it out, a pair of water-trapping layers made of nylon resin or the like are superimposed, and the periphery is sealed by surrounding it with a moisture-proof layer made of a laminated layer of trifluorochloroethylene film and modified polyolefin resin film. Sealed.

0003

[Problems to be Solved by the Invention] However, in EL panels manufactured using this manufacturing method, the moisture-proof function of the moisture-proof layer is not perfect, and even if left unlit for a long period of six months or more, , the brightness of the light-emitting layer deteriorates significantly due to humidity, and fundamental improvements to the moisture-proof layer are desired. For example,
As shown in Japanese Utility Model Publication No. 63-14393, it is disclosed that a glass plate with a thickness of 200 μm or less is interposed between a transparent electrode and a moisture-proof film, but a glass plate inevitably has the risk of breakage. There is also the problem that if the thickness is increased, flexibility will be impaired.

[0004] For this reason, it is conceivable to provide a thin glass film on the moisture-proof layer or water-trapping layer using a metal alkoxide solution using the sol-gel method, but in this method, the applied gel
Glass must be formed by heating at a drying temperature of 00°C to 900°C to avoid deterioration of materials with low melting points, such as the organic binder of the light emitting layer and reflective insulating layer, and the organic film of the light emitting moisture barrier layer and water trapping layer. 10 without damaging organic substances
There has been a strong desire for a new manufacturing method that forms a glassy transparent thin film using low-temperature drying treatment at temperatures below 0°C.

[0005] Therefore, an object of the present invention is to provide an EL panel that has improved moisture resistance without sacrificing conventional flexibility and that has significantly improved brightness deterioration due to changes over time due to moisture, and that also does not damage organic substances. An object of the present invention is to provide a method for manufacturing an EL panel in which a glassy transparent thin film is formed by a low-temperature drying process of 100° C. or lower without any drying.

[0006]

[Means for Solving the Problems] The EL panel of the present invention includes:
A light-emitting layer in which phosphor powder is dispersed in an organic binder and a reflective insulating layer are provided between the back electrode and the transparent electrode. In an EL panel equipped with a light-emitting substrate on which a pair of lead terminals are formed, a metal alkoxide solution is attached to the surface of the light-emitting substrate, dried at a drying temperature of 100°C or less, and then subjected to low-temperature plasma treatment. , a transparent thin film is formed over the entire surface of the light emitting substrate.

Further, in the EL panel of the present invention, a pair of water-trapping layers are further formed on the back electrode and the transparent electrode of the light-emitting substrate, and the transparent thin film is formed over the entire surface of the water-trapping layer. .

Furthermore, in the EL panel of the present invention, the thickness of the transparent thin film is 10 μm or less.

The method for producing an EL panel of the present invention involves forming a reflective insulating layer on the back electrode, coating the reflective insulating layer with a light-emitting layer in which phosphor powder is dispersed in an organic binder with a high dielectric constant, and A light-emitting substrate is formed by laminating a transparent electrode layer on the light-emitting layer, forming a current collection band on the periphery of this transparent electrode, and pulling out leads for voltage application from this current collection band and the back electrode, respectively. In the method for manufacturing an EL panel,
The light emitting substrate is coated with a metal alkoxide solution, dried at 100°C or less, and then subjected to low-temperature plasma treatment.
It is characterized in that a transparent thin film is formed covering the entire surface of the light emitting substrate.

[0010] Furthermore, the method for manufacturing an EL panel of the present invention includes:
The light emitting substrate manufacturing step further includes a step of laminating a pair of water trapping layers on the back electrode and the transparent electrode with their peripheral edges joined to each other, and immersing the metal alkoxide solution in the water trapping layers.

[0011] Various metals such as Al, Si, Ti, Zr, Sn, and Ce can be used as the metal in the metal alkoxide solution, but Al, Si, Ti, and Sn are preferable, and a metal alkoxide solution made from Si is particularly preferable. preferable.

0012

[Operation] The transparent thin film formed on the transparent electrode and the back electrode or on the water trapping layer provides an EL panel with good moisture resistance. Preferably, a moisture-proof layer made of a trifluorochlorinated ethylene film and a modified polyethylene resin film is formed on the transparent thin film to protect it from damage caused by external factors.

Furthermore, by setting the thickness of the transparent thin film to 10 μm or less, the flexibility of the EL panel is not impaired.

[0014] After drying at 100°C or less, a plasma-treated transparent thin film is covered over the entire surface of the light emitting substrate.
An unprecedented low-temperature drying process can be performed on organic substances with low melting points, such as the organic binder of the light-emitting layer and the reflective insulating layer, and the organic film of the light-emitting moisture-proof layer and the water-trapping layer, without causing any deterioration.

[0015]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 shows a schematic cross-sectional view of an EL panel according to an embodiment of the present invention.

The EL panel of this embodiment includes a light emitting substrate 2,
It consists of a transparent thin film 4 made of a silicon compound that covers the surface of the light emitting substrate 2 and has a thickness of about 3 μm, and a moisture-proof layer 6 that surrounds the transparent thin film 4 and seals the peripheral edge.

The light emitting substrate 2 includes a transparent electrode layer 8 made of a transparent conductive material such as In2O3 laminated on one side of a base such as a polyester film, a back electrode layer 10 made of Al foil, and a back electrode layer 10 laminated on the back electrode layer 10. ZnS:Cu is sandwiched between the reflective insulating layer 12, the transparent electrode layer 8 and the reflective insulating layer 12
A light emitting layer 14 made of electroluminescent phosphor particles such as those dispersed in an organic binder with a high dielectric constant, a current collecting band (not shown) formed on the periphery of the transparent electrode 8 and made of silver paste, A pair of electrode leads (not shown) for connecting the charging band and the back electrode 10 to an external power supply means, and a pair of water-trapping cables made of moisture-absorbing nylon that cover the current collecting band, the transparent electrode layer 8, and the back electrode layer 10. It consists of a layer 16.

The transparent thin film 4 is coated with a water-trapping layer 16 by a method described later.
The light emitting substrate 2 is formed on the light emitting substrate 2 except for the connection ends of the electrode leads.
The silicon compound is made of amorphous glass mainly made of silicon oxide.

The moisture-proof layer 16 is formed by laminating a trifluorochloroethylene film and a modified polyolefin resin film, and its peripheral portion is sealed by thermocompression bonding.

Next, a method for forming the transparent thin film 4 of amorphous glass on the light emitting substrate 2 in the EL panel constructed as described above will be explained.

First, the surface of the light emitting substrate 2 constructed as described above was degreased with isopropyl alcohol, and then the light emitting substrate 2 was subjected to plasma treatment. In this plasma treatment, argon gas is introduced into a glow discharge reaction vessel with a high frequency output of 50 W at a monomer flow rate of 10 c. c. (STP)/min, and pretreatment was performed for 3 minutes.

Next, this light-emitting substrate 2 is immersed in a metal alkoxide solution, and is heated to a depth of 5 cm at a temperature of 25° C. and a humidity of 40% RH.
/second, then temperature 25℃, humidity 40%RH
Dry under room temperature. Then, at a temperature of 70°C for 30 minutes,
It was heated and dried.

Then, the light emitting substrate 2 was placed in a glow discharge reaction container, and under an oxygen atmosphere, the high frequency output was 100 W, and the oxygen monomer flow rate was 8 c. c. /min for 10 minutes to cause a plasma reaction, thereby obtaining a transparent thin film 4 of amorphous glass.

The metal alkoxide solution described in the above-mentioned method for forming the transparent thin film 4 will now be explained.

Tetraethoxysilane [Si(OC2H5)4] is used as a metal alkoxide which is an organometallic compound.
20 ml of ethanol, 20 ml of ethanol, and 5 ml of 0.01 acetic acid aqueous solution are mixed to prepare a homogeneous alcohol solution. This alcohol solution is heated to 40° C. and refluxed for 24 hours to produce a high molecular weight sol through hydrolysis and polycondensation reactions. Add 20 ml of this high molecular weight sol ethylene glycol monoethyl ether, perform vacuum distillation to remove ethanol and water, and perform solvent replacement. Add isopropanol to this solvent-substituted solution,
The viscosity at 25°C was adjusted to 7.0 cp.

Next, the effects of this embodiment will be explained. In the EL panel configured in this manner, the thickness of the transparent thin film 4 is extremely thin, about 3 μm, so the flexibility is comparable to that of a conventional EL panel in which the transparent thin film 4 is not formed.

Furthermore, even if external moisture enters through the sealed portion of the modified polyolefin resin film at the periphery of the moisture-proof layer 16, the transparent thin film 4 of amorphous glass substantially blocks out the moisture. Even if there is moisture remaining inside the light-emitting layer 14 and the like, the remaining moisture is sufficiently absorbed by the water absorption layer 16, so that deterioration in brightness of the light-emitting layer 14 due to moisture is extremely small.

In a forced deterioration test at a temperature of 50° C. and a humidity of 95% RH, the driving conditions were the same as that of a voltage of 100 V and a frequency of 400 Hz. The half-life of the initial brightness of 52 nits (nt) in this EL panel is approximately 800 hours, whereas the half-life of this example's initial brightness of 49 nits (nt) is approximately 1,800 hours, which is more than twice as much. It was done.

(Example 2) In the above-mentioned Example 1, the transparent thin film 4 was formed on the water-trapping layer 16, but in this example, an EL panel was prepared without providing a water-trapping layer, as shown in FIG. I will explain while doing so.

As shown in FIG. 2, the light-emitting substrate 2' is a light-emitting substrate 2' in which the water-trapping layer 16 of Example 1 is not laminated on the current collecting band, the transparent electrode 8, and the back electrode 10, and as in Example 1, A transparent thin film 4 of amorphous glass is formed on this light emitting substrate 2',
Further, a moisture-proof layer 4 was formed on this transparent thin film 4 to produce an EL panel.

The EL panel constructed in this way has no inferiority in flexibility compared to a conventional EL panel in which the transparent thin film 4 is not formed, and also prevents external moisture from forming on the periphery of the moisture-proof layer 16. Even if moisture enters through the sealed portion of the modified polyolefin resin film, the transparent thin film 4 of amorphous glass will substantially block moisture.

A forced deterioration test at a temperature of 50° C. and a humidity of 95% RH was performed under the same driving conditions as a voltage of 100 V and a frequency of 400 Hz. The half-life of an initial brightness of 52 nits (nt) in this EL panel is approximately 500 hours, whereas the half-life of this example's initial brightness of 50 nits (nt) is approximately 1,600 hours, an improvement of more than three times. It was done.

In the above explanation, the dipping method in which the light emitting substrate 2 or 2' is immersed in a metal alkoxide solution has been explained, but the present invention is not limited to the dipping method, but can also be applied to other spray methods, spin coating methods, and screen methods. Any of the following is acceptable.

Further, in the above explanation, trifluorochloroethylene was selected as the material for the moisture-proof layer 6, but the present invention is not limited to this, and the present invention is not limited to this, but can be made by laminating polyester resin and polyethylene resin containing vinyl acetate. It goes without saying that other surface protection films such as polyester films may also be used.

[0036]

[Effects of the Invention] As explained above, according to the present invention,
It is possible to provide an EL panel that has improved moisture resistance without sacrificing conventional flexibility and has significantly improved brightness deterioration due to changes over time due to moisture, and also has a low temperature of 100 degrees Celsius or less without damaging organic substances. It is possible to provide a method for manufacturing an EL panel in which a glassy transparent thin film is formed through drying treatment.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing an EL panel according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing an EL panel according to another embodiment of the present invention.

[Explanation of symbols]

2, 2’ Light emitting board 4 Transparent thin film 6 Moisture barrier layer 8 Transparent electrode 10　　　　　　Back electrode 12 Reflective insulation layer 14 Luminescent layer 16 Water catchment layer

Claims (5)

[Claims] 1. A light-emitting layer in which phosphor powder is dispersed in an organic binder and a reflective insulating layer are provided between the back electrode and the transparent electrode, and a current collecting band formed on the periphery of the transparent electrode and the back surface are provided. In an EL panel provided with a light emitting substrate on which a pair of lead terminals each drawn out from an electrode are formed, a metal alkoxide solution is adhered to the surface of the light emitting substrate and the temperature is increased to 100°C.
An EL panel characterized in that a transparent thin film is formed over the entire surface of the light emitting substrate by drying it at a drying temperature below and then subjecting it to low temperature plasma treatment. 2. A pair of water trapping layers are further formed on the back electrode and the transparent electrode of the light emitting substrate, and the transparent thin film is formed over the entire surface of the water trapping layer. The EL panel according to claim 1. 3. The EL according to claim 1 or 2, wherein the transparent thin film has a thickness of 10 μm or less.
panel. 4. A reflective insulating layer is formed on the back electrode, a light emitting layer in which phosphor powder is dispersed in an organic binder is coated on the reflective insulating layer, and a transparent electrode layer is laminated on the light emitting layer,
In the method for manufacturing an EL panel, a light-emitting substrate is formed by forming a current collecting band on the periphery of the transparent electrode, and pulling out voltage application leads from the current collecting band and the back electrode, respectively. A method for manufacturing an EL panel, which comprises applying a metal alkoxide solution, drying it at 100° C. or lower, and then subjecting it to low-temperature plasma treatment to form a transparent thin film covering the entire surface of a light emitting substrate. 5. The light emitting substrate producing step further includes:
5. The method according to claim 4, further comprising the step of bonding the peripheral edges of a pair of water-trapping layers to each other and laminating them on the back electrode and the transparent electrode, respectively, and immersing the metal alkoxide solution in the water-trapping layers. A method for manufacturing an EL panel.