JPH04293971A - Dielectric resin composition and dispersed el element - Google Patents

Abstract

PURPOSE:To produce, quickly at a high productivity, the title element which is uniform in luminance and is expected to have a high luminance and a long life. CONSTITUTION:A dielectric resin compsn. prepd. by dissolving a cyanoethylated polymer in a monomer having both a (meth) acryloyl group and a cyanoethyl group in the molecule is mixed with a powdered stimulable phosphor to give a coating material for a luminous layer. Separately, the compsn. is mixed with an inorg. highly dielectric powder to give a coating material for a reflective insulation layer. Then, a dispersed EL element comprising the luminous layer and the reflective insulation layer held between a counter electrode and a back electrode is prepd. The compsn. cures quickly by the irradiation with an electron beam, forming the luminous layer and the reflective insulation layer instantaneously.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is used as a binder for dispersion electroluminescence (hereinafter referred to as dispersion EL elements), which is expected to have high productivity, uniform brightness, and long life. The present invention relates to a dielectric resin composition and a dispersion type EL device.

0002

[Prior Art] Dispersion type EL devices generally use a metal foil such as aluminum foil as a back electrode, and an inorganic high dielectric powder such as titanium oxide or barium titanate is coated on this back electrode with an organic high dielectric binder (hereinafter referred to as This is simply called a binder) to form a reflective insulating layer. A light-emitting layer is formed on the reflective insulating layer by dispersing phosphor powder such as zinc sulfide in a binder, and finally a transparent electrode such as a mixture of indium oxide and tin oxide (hereinafter referred to as ITO) is formed as a counter electrode. It is set up as.

Dispersion type EL elements are packaged with a moisture-absorbing film such as nylon, and further packaged with a moisture-proof film such as polychlorotrifluoroethylene.

[0004] As the binder added to the reflective insulating layer and the light emitting layer, cyanoethylated polyols, cyanoethylated pullulan, etc. proposed in JP-A-51-132500, JP-A-59-96104, etc. are used. Polymer cyanoethylated products including cyanoethylated sugars are known. These cyanoethylated polymers are dissolved in a solvent such as acetone or N,N-dimethylformamide, and inorganic high dielectric powder or phosphor powder is dispersed in the solution.

After applying this solution to the back electrode or reflective insulating layer, the binder is solidified by drying.
A reflective insulating layer or a light emitting layer is formed. Further, in the laminate of the counter electrode, the counter electrode and the light emitting layer are bonded together by thermocompression using a heated roll or the like.

[0006]

[Problems to be Solved by the Invention] By the way, when using the conventional method of coating a luminescent layer or an insulating layer and then drying it to form a coating film, it takes at least ten minutes to several hours to dry the coating film. It is. Furthermore, there is a possibility that defects may occur in the coating film due to evaporation of the solvent. Furthermore, when laminating the counter electrode, the binder, which has been once dried by evaporation, is heated and melted, so time is required to melt the binder. As a result, it has become difficult to laminate at a high speed of 2 m/min or more.

Moreover, since the luminescent layer is coated on the insulating layer that has been coated and dried, a portion of the surface of the insulating layer that has already been formed swells or dissolves due to the organic solvent in the coating solution, resulting in uniform luminescence. be hindered. Additionally, there is also the problem that defects and brightness unevenness are likely to occur.

The present invention was devised to solve these problems, and it is an object of the present invention to provide a distributed EL element that is highly productive, has no uneven brightness, and can be expected to have high brightness and a long life. With the goal.

[0009]

[Means for Solving the Problems] In order to achieve the object, the dielectric resin composition of the present invention is a composition in which a polymeric cyanoethyl compound is dissolved in a monomer having a (meth)acryloyl group and a cyanoethyl group in the molecule. Contains as a binder component.

Further, the dispersion type EL element has a layer structure in which a light emitting layer containing a phosphor powder and a binder and a reflective insulating layer containing an inorganic high dielectric powder and a binder are sandwiched between a counter electrode and a back electrode. As a binder for the light-emitting layer and the reflective insulating layer, a dielectric resin composition in which a polymeric cyanoethylated compound is dissolved in a monomer having a (meth)acryloyl group and a cyanoethyl group in the molecule is used.

[0011]

[Function] The binder used in the present invention is a polymeric cyanoethyl compound dissolved in a monomer having a cyanoethyl group and a (meth)acryloyl group in the molecule. Generally, one of the characteristics required of a binder for a dispersed EL device is a high dielectric constant.
By dissolving a polymeric cyanoethyl compound in a monomer having a cyanoethyl group in the molecule, the binder comes to exhibit a high dielectric constant. Furthermore, by dissolving the polymeric cyanoethylated product, the coating properties are improved and the coating film becomes tougher than when the monomer is used alone. Furthermore, improvements in electrical properties such as dielectric constant and tan δ can also be expected.

Furthermore, since the monomer has a (meth)acryloyl group, it can be cured with an electron beam. A specific example of a monomer used as such a binder is 2-cyanoethyl (meth)acrylate.

[0013] A high molecular weight cyanoethylated product is dissolved in this monomer. The concentration of the polymeric cyanoethylated product is 1 to 4.
0% by weight is preferred. The cyanoethylated polymer preferably has a cyanoethyl group content of 35% or more, and includes cyanoethylated products such as cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, and methylcellulose, and cyanoethyl saccharose, which have been conventionally used as binders. things are used. These cyanoethylated polymers can be used alone or in the form of a mixture of two or more. The dielectric constant of the binder after being cured with an electron beam is preferably 15 or more (1 kHz, 25° C.).

[0014] Inorganic dielectric powder such as titanium oxide or barium titanate is dispersed in this binder at a weight ratio of about 1:1 to 1:10 and then coated with a knife coater, roll coater, blade coater, screen printing, etc. Coat on the back electrode by Thereafter, the binder is cured by electron beam irradiation to form a reflective insulating layer. Then,
A phosphor powder dispersed in a binder at a weight ratio of 1:1 to 1:10 was applied in the same manner, and a counter electrode such as ITO was immediately vapor-deposited on a film such as polyethylene terephthalate (hereinafter, this is simply referred to as a counter electrode). After laminating the substrates (referred to as ), electron beams are similarly irradiated to simultaneously cure the light-emitting layer and bond the counter electrode.

Since the reflective insulating layer after electron beam irradiation is cured and crosslinked, it will not dissolve or swell in the coating solution for forming the luminescent layer, and there is no risk of uneven luminescence or defects. In addition, since the curing reaction by electron beams occurs extremely quickly, curing of the light emitting layer and the reflective insulating layer is completed instantaneously. In this regard, in the conventional method, when laminating the counter electrode, the binder that has been dried once is melted, so lamination takes time. On the other hand, in the case of curing by electron beam irradiation, the counter electrode is laminated with the luminescent layer uncured, that is, in a fluid state, so there is no need to melt the binder, and the counter electrode can be laminated in a short time. finish. Moreover, since the solvent is not evaporated, defects are less likely to occur in the coatings of the light-emitting layer and reflective insulating layer, and improvements in brightness and life can be expected.

[0016] The irradiation dose of the electron beam is 10 to 300 kGy.
is preferred. If the irradiation dose is less than 10 kGy, curing will be insufficient. On the other hand, if the irradiation dose exceeds 300 kGy, the brightness will become insufficient due to a decrease in dielectric constant, coloring of the binder, deterioration of the phosphor, etc. Further, after coating each layer, it is desirable to heat the coating at a temperature of about 80 to 100° C. in order to remove moisture immediately before curing.

[0017]

[Example] Example: 2-cyanoethyl acrylate (M
ORTON THIOKOL. INC. Manufactured by RC-10
0) with cyanoethyl pullulan (CR manufactured by Shin-Etsu Chemical Co., Ltd.)
Zinc sulfide phosphor powder (Sylvania Type manufactured by GTE) was added to the binder dissolved at 20% by weight in -S).
e728) mixed and dispersed in a weight ratio of 1:4 for the luminescent layer, and a reflective insulation layer paint in which barium titanate was mixed and dispersed in the same binder at a weight ratio of 1:4. Prepared.

[0018] Paint for reflective insulating layer is applied to 20 μm of hard aluminum foil with a thickness of 100 μm by screen printing method.
It was applied to a film thickness of . After heating this to 80°C, it was irradiated with an electron beam at an irradiation dose of 20 kGy and an acceleration voltage of 200 kV.
The reflective insulation layer was cured.

[0019] A coating for the luminescent layer was similarly applied to a thickness of 40 μm over this, and after heating to 80°C, a counter electrode (T-coat SA75 manufactured by Teijin Ltd.) was laminated and accelerated at an irradiation dose of 50 kGy. The light emitting layer was cured by irradiation with an electron beam at a voltage of 200 kV. This is coated with a moisture-absorbing film (Diamid ZS13 manufactured by Daicel Chemical Industries, Ltd.).
After packaging with 5), further packaging with a moisture-proof film (Nitoflon 4810 manufactured by Nitto Denko Corporation),
A distributed EL device was fabricated.

The time required for curing the luminescent layer and the reflective insulating layer was less than 1 second, and the lamination speed of the counter electrode was 1 second.
The speed was 0 m/min. Further, the brightness at 100V/400Hz was 123 cd/m2, and no brightness unevenness was observed.

Comparative Example 1: Cyanoethyl pullulan, cyanoethyl polyvinyl alcohol (manufactured by Shin-Etsu Chemical Co., Ltd.)
Zinc sulfide phosphor (Sylvania Type 7 manufactured by GTE) was added to a polymer solution in which CR-V) and N,N-dimethylformamide were mixed at a weight ratio of 7:3:33.
28) in a weight ratio of 1:4 and a coating for a reflective insulating layer in which barium titanate was mixed and dispersed in the same polymer solution in a weight ratio of 1:4. Prepared the paint.

[0022] Then, a paint for a reflective insulating layer was applied to the same back electrode as in the example so that the film thickness after drying was 20 μm. The paint was then dried by heating at 130°C for 1 hour. A paint for a light-emitting layer was applied thereon so that the film thickness after drying was 40 μm, and dried in the same manner. Furthermore, a counter electrode is thermocompression bonded to the light emitting layer using a heating roll from above, and then it is packaged with a moisture absorbing film and a moisture proofing film in the same manner as in the example to form a dispersed EL.
The device was fabricated.

In this case, the time required for solidifying the light emitting layer and the reflective insulating layer was as long as 1 hour. Furthermore, the lamination speed of the counter electrode was as low as 30 cm/min. Furthermore, the luminance at 100V/400Hz was as low as 105 cd/m2.

Comparative Example 2: In the example, acrylonitrile was used instead of 2-cyanoethyl acrylate,
A distributed EL device was fabricated. In this case, 100V/40
The brightness at 0 Hz was only 20 cd/m2.

Comparative Example 3: In the example, methyl ether of pullulan was used instead of cyanoethyl pullulan to produce a dispersion type EL device. In this case, 100V/
The brightness at 400Hz was only 7 cd/m2.

Comparative Example 4: A dispersion type EL device was prepared using dimethyl acrylamide instead of 2-cyanoethyl acrylate in the example. In this case, 100V
The brightness at /400Hz was only 10 cd/m2.

[0027]

As explained above, the present invention uses a dielectric resin composition in which a polymeric cyanoethyl compound is dissolved in a monomer having an acryloyl group and a cyanoethyl group in the molecule. When this resin composition is irradiated with an electron beam, a curing reaction proceeds rapidly, and a light-emitting layer and a reflective insulating layer are instantly formed. Therefore, it is possible to obtain a dispersed EL element with high productivity, uniform brightness, high brightness, and long life.

Claims (2)

[Claims] 1. A dielectric resin composition containing, as an electron beam curable binder component, a polymer cyanoethyl compound dissolved in a monomer having a (meth)acryloyl group and a cyanoethyl group in the molecule. 2. A dispersion-type EL element in which a light-emitting layer containing a phosphor powder and a binder and a reflective insulating layer containing an inorganic high dielectric powder and a binder are sandwiched between a counter electrode and a back electrode, wherein the light-emitting layer and the A dispersion type EL device characterized in that the binder of the reflective insulating layer is the dielectric resin composition according to claim 1.