JPH03210790A - Distributed EL lamp - Google Patents

Abstract

PURPOSE:To improve luminous efficiency by using cyano ethylated xylitol, etc., as a binder. CONSTITUTION:Cyano ethylated xylitol is mixed with cyano ethylated high polymer dielectric to be used. At that time the cyano ethylated xylitol is used by 10wt.% or more preferably 20wt.% or more, and the cyano ethylated high polymer dielectric is employed by 90wt.% or less preferably 80wt.% or less. An illuminant layer, in which fluorescent powder is distributed in the binder of a composition substance, is held between a transparent electrode and a back electrode. Also an insulation body layer is provided in which inorganic high dielectric powder is distributed in a binder including the cyano ethylated xylitol or the composition substance containing cyano ethylated xylitol of 10wt.% or more and the cyano ethylated high polymer dielectric of 90wt.% or less.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a distributed EL lamp, and more particularly to a distributed EL clamp with improved luminous efficiency.

<Prior art> Distributed EL lamps generally use a metal foil such as aluminum foil as a back electrode, and on this back electrode, inorganic high dielectric powder such as titanium oxide or barium titanate is dispersed in an organic high dielectric binder. A reflective insulator layer is formed on top of the reflective insulator layer, and then a light-emitting layer is formed by dispersing phosphor powder such as zinc sulfide in an organic high dielectric binder, and finally a layer of ITO (a mixture of indium oxide and tin oxide) is formed. It has an iQ@ structure with a transparent electrode as a counter electrode, and the phosphor emits light by applying an alternating current voltage between both electrodes.

Note that a distributed EL clamp is used in which only a light emitting layer is sandwiched between a back electrode and a transparent electrode.

The binder for the phosphor layer and insulator layer used in such an EL clamp is required to have a high dielectric constant. As conventional EL clamp binders, cyanoethylated polymeric dielectrics such as cyanoethylated cellulose, cyanoethylated poval, cyanoethylated hydroxyethylcellulose, cyanoethylated pullulan, and cyanoethylated starch have been used. However, these binders have a dielectric constant of about 10 to 20 and cannot provide sufficient brightness.

Therefore, as described in Patent Application Publication No. 15937/1983, cyanoethylated sorbitol, cyanoethylated diglycerin, cyanoethylated pentaerythritol, cyanoethylated trimethylolpropane, cyanoethylated inositol, cyanoethylated methylglucose, etc. It has been proposed to increase the dielectric constant by using a mixture of a low molecular weight cyanoethylated polyol and a cyanoethylated polymeric dielectric exhibiting a high dielectric constant of 20-60 as a binder.

The above-mentioned cyanoethylated product can be obtained by reacting a compound having a hydroxyl group with acrylonitrile in the presence of an alkali according to the synthesis method described in US Pat. No. 3,161,539, US Pat.

For example, about 0.2 moles of sodium hydroxide per hydroxyl group in the polyol molecule is added as a 10% aqueous solution to make an alkaline solution, and about 1.5 times the mole of acrylonitrile is added to the solution with stirring at a reaction temperature of 35 to 45 degrees Celsius. Add dropwise over ~60 minutes. After stirring at the same temperature for about 2 hours, the resulting cyanoethylated polyol was extracted with an appropriate amount of an organic solvent (chloroform, ethyl acetate, etc.), and then extracted with water, 1N acetic acid (
or 1N hydrochloric acid) and water, dried over anhydrous 'fAM calcium, the organic solvent was distilled off under reduced pressure, and
℃ and 0.5 maH9 for 3 to 5 hours to completely remove volatile components.

Although the dispersion type EL clamp using the thus obtained cyanoethylated polyol and cyanoethylated polymeric dielectric as a binder could exhibit sufficient brightness, it was still not sufficient in terms of luminous efficiency.

<Problems to be Solved by the Invention> As mentioned above, the characteristics required for the EL clamp include life span and luminous efficiency in addition to brightness. With the miniaturization of personal computers and word processors, it is desired that the power consumption of EL clamps used for backlighting of liquid crystals be reduced. Particularly in the case of a portable device, since it is driven by a battery, if the power consumption by the EL clamp is large, the usable time will be significantly shortened. The intensity of light emitted per unit of power consumption is expressed as luminous efficiency. In other words, the higher the conversion rate to light energy per consumed electric power, the better the luminous efficiency.

When a conventional binder with a high dielectric constant is used, there is no significant difference in the luminous efficiency of any compound, and E with high luminous efficiency is used.
L clamp was not obtained. The efficiency of light emission is considered to be related to the dielectric constant, dielectric loss tangent, and insulation resistance of the binder.

<Means for Solving the Problems> In order to solve the above problems, the inventors of the present invention have conducted intensive studies to solve the above-mentioned problems.In particular, when using cyanoethylated xylitol as a binder among the cyanoethylated polyols with a small carbon number. It was discovered that a distributed EL clamp not only has excellent brightness but also has extremely high luminous efficiency, and based on this knowledge, the present invention was accomplished. It is truly surprising that when using cyanoethylated xylitol, a distributed EL clamp with particularly good luminous efficiency can be obtained.

The cyanoethyl xylitol of the present invention can be produced by reacting xylitol with acrylonitrile in the presence of an alkali COH OCH COH 0820.

The cyanoethylation substitution rate used is generally 95% or more, preferably 99% or more, more preferably 99.5% or more.

Although cyanoethylated xylitol can be used alone as a binder, it is used in combination with a cyanoethylated polymeric dielectric. When used in combination with a cyanoethylated polymeric dielectric, cyanoethylated xylitol has a 10f!
Φ% or more, preferably 2°! ! i! m% or more is used,
The cyanoethylated polymeric dielectric material is used in an amount of 90% by weight or less, preferably 80% by weight or less. The cyanoethylated polymeric dielectric material is preferably used because when mixed with cyanoethylated xylitol, which is a liquid, it has the effect of reducing its fluidity and stabilizing the dispersion of high dielectric fine particles such as phosphor particles and barium titanate. .

The cyanoethylated polymer dielectric has a dielectric constant of 10 or more (
Those that are solid at room temperature (1 kHz, 25°C) are preferable, such as cyanoethylated poval, cyanoethylated ethylene vinyl alcohol copolymer, cyanoethylated pullulan, cyanoethylated cellulose, cyanoethylated hydroxyethylcellulose, and cyanoethylated starch. One or more of these can be used.

Generally, cyanoethylated polyols are liquid or waxy, and the lower the molecular weight, the higher the dielectric constant, and the higher the EL clamp brightness when used as a binder. However, it is thought that the lower the molecular weight, the higher the dielectric loss tangent, and the higher the power loss due to lower insulation resistance, the lower the luminous efficiency.

On the other hand, if the molecular weight is too high, the dielectric constant will decrease and the brightness will decrease. Cyanoethylated xylitol has 5 carbon atoms and has favorable values for dielectric constant, dielectric loss tangent, and insulation resistance, and is considered to have high brightness and exceptionally high luminous efficiency.

The dispersion type EL clamp is produced by a known method using a binder containing cyanoethylated xylitol or a composition of 10% by weight or more of cyanoethylated xylitol and 90% by weight or less of a cyanoethylated polymeric dielectric. One example will be described.

Dissolve the binder in the solvent and get 5-5G! A solution containing 100 parts by weight of binder is dispersed and mixed with 50 to 900 parts of non-mai and dielectric powder to obtain a uniform slurry. This is applied to the back electrode by a general method such as screen printing or casting, and the solvent is evaporated and dried to form a reflective insulator layer. On the other hand, binder 100! is added to the binder solution! A uniform slurry is obtained by dispersing and mixing 50 to 900 ml of phosphor per volume.

This is applied onto the reflective insulator layer in the same manner as above, and the solvent is evaporated and dried to form a light-emitting layer. Next, electrode terminals are attached to the glass coated with the removed coating film and the transparent electrode film, respectively, and the conductive surfaces of the coating film and the transparent electrode are brought into contact with each other to form a composite structure. A distributed EL element is obtained.

Note that a dispersed EL lamp having only a light emitting layer sandwiched between a back electrode and a transparent electrode is also manufactured by the same method.

That is, cyanoethylated xylitol or cyanoethylated xylitol 10! A binder containing a composition of 1Φ% or more and 90% by weight or less of a cyanoethylated polymeric dielectric is dissolved in a solvent to prepare a 5 to 50% by weight solution, and 50% by weight of a phosphor is added to 100 parts by weight of the binder. ~900 parts by weight are dispersed and mixed to obtain a uniform slurry. This slurry is applied to the back electrode and the solvent is evaporated to dryness to form a light emitting layer. Next, after attaching electrode terminals to the glass or transparent electrode film coated with the obtained coating film and transparent electrode,
The coating film is brought into contact with the conductive surface of the transparent electrode and is integrated to obtain a dispersed EL lamp.

The phosphor used here may be any phosphor commonly used for EL devices, such as zinc sulfide and selenium sulfide.

Further, the inorganic dielectric powder may be any powder normally used in dispersion type EL clamps, such as titanium oxide or barium titanate.

Solvents used to prepare the binder solution include, for example, N,N"dimethylformamide (DMF).
, N,N'-dimethylacetamide, dimethylsulfoxide, acetone, methyl ethyl ketone, acetonitrile and the like.

As the electrode, any electrode that is normally used in EL elements can be used, but for the back electrode, for example, one with a thickness of about 50 mm to
A 100 μm aluminum plate or metal evaporator I1m may be used as the transparent electrode, for example, with a thickness of approximately 75 to 125 μm.
One example is one in which ITO is placed on one surface of a μm polyester film to impart conductivity.

<Effects of the Invention> The dispersion type EL device of the present invention uses cyanoethylated xylitol or a mixture of cyanoethylated xylitol and a cyanoethylated polymeric dielectric material as a binder for the light-emitting layer or the light-emitting layer and the insulating layer. Compared to the cyanoethylated polyol used, it is not only comparable in brightness but also extremely superior in luminous efficiency. Since the distributed EL clamp of the present invention has excellent luminous efficiency, it is particularly suitable for manufacturing EL lamps for backlights of portable personal computers and word processors.

The following will explain based on examples.

Example 1 A mixture of cyanoethylated xylitol 309 and cyanoethylated pullulan 309 was dissolved in DMF to prepare a 30% binder solution. Barium titanate (BT-1 manufactured by Fuji Titanium Co., Ltd., manufactured by Fuji Titanium Co., Ltd.) was added to 100 g of this solution as an inorganic high dielectric material.
00M) powder was cross-dispersed to form a uniform slurry, which was coated on an aluminum plate to form a reflective insulator layer with a dry thickness of 30 μm.

On the other hand, 98.4 fl of zinc sulfide (Siluania 723 powder manufactured by GTE Products Co., Ltd.) was cross-dispersed as a phosphor in the binder solution 1009 to form a uniform slurry, and the slurry was coated on the reflective insulator layer to form a luminescent layer with a dry film thickness of 55 μm. was formed.

The laminate created by the above series of steps is 10c
It was cut to a size of 1 x 10 cll, attached with lead terminals, and dried.

On the other hand, a transparent conductive film made of polyethylene terephthalate with an ITO film formed on one side was also made of 1G3 x 10
After cutting into a size α and attaching lead terminals, the light-emitting layer of the laminate described above and the ITO surface of the transparent conductive film were heated and laminated. Thereafter, nylon films were laminated on the surfaces of the back electrode and the front electrode, respectively, and the entire periphery was surrounded and sealed with a polytrifluoroethylene chloride film.

100V -4008z between both electrodes of the obtained EL element
The brightness when an AC electric field of 125 Cd/-d is applied, and the luminous efficiency is 8. The weight was m/14 (lumens/watt).

Note that the luminous efficiency was determined based on luminance and power consumption per unit area of the EL clamp.

Example 2 An EL lamp was produced in the same manner as in Example 1 except that cyanoethylated poval was used instead of cyanoethylated pullulan. Brightness at 100V-400 weight 2 is 10
The luminous efficiency was 8.4 Is/14.

Example 3 An EL clamp was prepared in the same manner as in Example 1 except that cyanoethylated human oxyethyl cellulose was used instead of cyanoethylated pullulan.

The brightness at 100 V-40082 is 4 Cd/weight
m, and the luminous efficiency was 8.71-8.

Comparative Example 1 EL was carried out in the same manner as in Example 1 except that cyanoethylated sucrose was used instead of cyanoethylated xylitol.
I made a prototype clamp. The weight density at 100V-400H2 was 91 cd/d, and the luminous efficiency was 5.71 s/W.

Comparative Examples 2 to 6 Cyanoethylated sorbitol (Comparative Example 2), cyanoethylated diglycerin (Comparative Example 3), cyanoethylated trimethylolpropane (Comparative Example 4), and cyanoethylated glycerin (Comparative Example 5) were used instead of cyanoethylated xylitol, respectively. An EL lamp was experimentally produced in the same manner as in Example 1 except that the lamp was used.

Further, as Comparative Example 6, only cyanoethylated pullulan was used as a binder. Each EL clamp 100V -4
Table 1 shows the luminance and luminous efficiency at 00 Hz.

Example 4 A mixture of cyanoethylated xylitol 309 and cyanoethylated pullulan 30g was dissolved in DMF to prepare a 30% binder solution. This solution 1009 was added with zinc sulfide as a phosphor (Siluania 7 manufactured by GTE Products Co., Ltd.).
98.4 g of No. 23 powder was mixed and dispersed to form a uniform slurry, and the slurry was coated on an aluminum plate to form a luminescent layer with a dry WA thickness of 55 μm.

The laminate created by the above series of steps is 10c
It was cut into a size of m x 10 cm, a lead terminal was attached, and then dried.

On the other hand, ITOII was applied to one side of polyethylene terephthalate.
The transparent conductive film that formed A was also 10caX1
After cutting to a size of 0 cm and attaching lead terminals, the light emitting layer of the above-described laminate and 170 sides of the transparent conductive film were heated and laminated. Thereafter, nylon films were laminated on the surfaces of the back electrode and the front electrode, respectively, and the entire periphery was surrounded and sealed with a polytrifluoroethylene chloride film.

When an alternating current electric field of 100V-400H2 was applied between both electrodes of the obtained EL element, the luminance was 125 cd/rd and the luminous efficiency was 7.5 In/-.

Example 5 Cyanoethylated xylitol 609 was dissolved in DMF,
A 30% binder solution was prepared. Using this solution,
An EL device was obtained in the same manner as in Example 4.

When an alternating current electric field of 100 V-400 H2 was applied between both electrodes of this EL element, the luminance was 130 cd/-, and the luminous efficiency was 7.0 In8.

Procedural amendment March 12, 1990 1.Display of the incident 1990 Patent Application No. 5595 2. Name of the invention Decentralized EL clan person who makes corrections Relationship with the incident

Claims (2)

[Claims] (1) A light-emitting layer in which phosphor powder is dispersed in a binder containing cyanoethylated xylitol or a composition of 10% by weight or more of cyanoethylated xylitol and 90% by weight or less of a cyanoethylated polymeric dielectric is used as a transparent electrode and a back electrode. A distributed EL lamp sandwiched between (2) A claim further comprising an insulating layer in which an inorganic high dielectric powder is dispersed in a binder containing cyanoethylated xylitol or a composition of 10% by weight or more of cyanoethylated xylitol and 90% by weight or less of a cyanoethylated polymeric dielectric. Item 1. Distributed EL lamp according to item 1.