JPH04312790A - Humidity-resistant electroluminescent lamp - Google Patents

Abstract

PURPOSE:To obtain an EL lamp having high humidity resistance and a long life. CONSTITUTION:In an organic dispersion-type electroluminescent lamp using an organic polymer matrix for a light-emitting layer and/or an insulating layer, ethylene-alpha,beta-olefinic unsaturated carboxylic acid or its salt copolymer prepared by copolymerization of >=50wt.% of ethylene, 3-50wt.% of alpha,beta-olefinic unsaturated carboxylic acid or its salts, and 0-40wt.% of vinyl-containing compounds is used as the organic polymer matrix to give a humidity-resistant electroluminescent lamp.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic dispersed electroluminescent lamp (hereinafter referred to as EL lamp). Specifically, in an organic dispersed EL lamp using an organic polymer matrix for a light emitting layer and/or an insulating layer,
An object of the present invention is to provide an EL lamp with excellent moisture resistance by using a specific organic polymer resin as an organic polymer matrix.

0002

[Prior Art] In recent years, copper and/or copper have been used as backlights for display devices and interior and exterior panel lights for automobiles due to their characteristics such as uniform brightness over a wide area and light weight.
Alternatively, EL lamps using zinc sulfide-based phosphors containing mainly zinc sulfide, such as silver-activated zinc sulfide, copper- and manganese-activated zinc sulfide, and copper-activated zinc sulfide selenide, have been used.

[0003] Phosphors have the disadvantage that they are sensitive to moisture and their brightness rapidly decreases due to moisture entering from the outside. Therefore, conventionally used EL lamps have an insulating layer on the back electrode, a light emitting layer made of a mixture of a highly dielectric organic binder and a phosphor, and a transparent electrode layer, and each electrode layer has a terminal for conducting electricity. A moisture-absorbing film such as nylon is placed on the EL element to prevent moisture from entering, and a PCTF film is placed on top of this to cover the entire EL element.
It is used by being covered with a moisture-proof layer such as E (polychlorotrifluoroethylene) film.

[0004] In such a method, exposure to high temperature and high humidity is required for a long time, or for a long period of time exceeding 10 years.
When the EL lamp is exposed indoors or outdoors, moisture penetrates through the film. Since water itself is a liquid high dielectric material with a dielectric constant of about 80, the intrusion of some water causes the EL capacitor to function with enhanced characteristics rather than before water intrusion, and thus has the effect of increasing brightness.

However, if moisture further penetrates and reaches the insulating layer, the insulating materials such as barium titanate, barium strontium titanate, barium lead titanate, barium lead tin titanate, etc., are mainly used as insulating materials. As a result of hydrolysis of ferroelectric insulating materials containing barium (BaTiO3), alkaline earth metal ions (B
a2+, Sr2+, etc.).

[0006] The ions not only impair the insulation properties of the insulating layer and reduce the brightness and luminous efficiency, but also back-diffuse into the emissive layer, resulting in a loss of the insulating properties of the emissive layer, resulting in a sudden decrease in brightness. This significantly shortens the life of the EL lamp.

Therefore, in order to solve this problem, desiccant agents such as silica gel, calcium oxide, calcium carbonate, calcium sulfate, and barium oxide, and/or nylon film, super absorbent resin film, etc. are added to the inside of the moisture-proof film envelope. A method of coating a water-repellent substance on the hygroscopic layer or light-emitting layer of the Exposure indoors and outdoors for many years is unavoidable, reducing the function of the EL capacitor and shortening the life of the EL lamp.

[0008]

[Problem to be solved by the invention] In view of the above situation,
As a result of intensive studies aimed at providing a long-life EL lamp with excellent moisture resistance, the present inventor found that when a specific organic polymer resin is used for the light-emitting layer and/or the insulating layer, sufficient moisture resistance is achieved. The present inventors have discovered that it is possible to provide an EL lamp having the following characteristics, and have completed the present invention.

[0009]

[Means for Solving the Problems] That is, the present invention provides an organic dispersed EL lamp using an organic polymer matrix in a light emitting layer and/or an insulating layer, in which the organic polymer matrix contains 50% by weight or more of ethylene, 3 ~50% by weight α, β
- an olefinic unsaturated carboxylic acid or a salt thereof, and 0
A moisture-resistant electroluminescent lamp characterized by using a copolymer of ethylene-α,β-olefinic unsaturated carboxylic acid or its salt obtained by copolymerizing ~40% by weight of a vinyl group-containing compound. It is on offer.

The present invention will be explained in more detail below. In the present invention, the copolymer made of ethylene-α,β-olefinic unsaturated carboxylic acid or its salt, which is applied as an organic polymer matrix for the light-emitting layer and/or the insulating layer, contains at least 50% by weight of ethylene, 50% by weight of α,β-olefinic unsaturated carboxylic acid or salt thereof,
It is a copolymer of 0 to 40% by weight of a vinyl group-containing compound, and is usually used as a self-emulsifying emulsion by neutralizing and stirring with an aqueous and/or alcoholic solution of an ammonium salt or amine salt.

These copolymers and their production method are disclosed in JP-A-48-32984, but the α,β-olefinic unsaturated carboxylic acid used in the copolymerization is an unsaturated linear or cyclic chain. There are monocarboxylic acids and dicarboxylic acids having , such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, citric acid, maleic acid, and fumaric acid, which can be used alone or in combination.

[0012] Vinyl compounds that can be used in the copolymerization include vinyl esters such as vinyl formate,
Vinyl acetate, vinyl chloroacetate, vinyl glycolate, vinyl cyanoacetate, vinyl propionate, vinyl butyrate, etc., alcohols with 1 to 12 carbon atoms and acrylic acid, methacrylic acid, crotonic acid, itaconic acid, citric acid, Examples include esters with maleic acid and fumaric acid, vinyl chloride, vinylidene chloride, acrylamide, acrylonitrile, and the like, and these can be used alone or in combination.

[0013] The above raw materials are usually tertiary butyl alcohol,
γ in a solvent consisting of aliphatic alcohols such as methanol and isopropanol, ketones such as acetone, esters such as ethyl acetate and butyl acetate, saturated hydrocarbons such as n-hexane and cyclohexane, and water alone or in a mixture. Polymerization is initiated by irradiation with ionizing radiation such as a beam or an electron beam, at a polymerization pressure of 10 atm to 500 atm and a polymerization temperature of 100 atm.
It can be done at temperatures below ℃.

The copolymer obtained by the above production method is usually used as an aqueous liquid and/or alcoholic liquid of a self-emulsifying emulsion by coating and drying. To make the copolymer self-emulsifying, the carboxylic acid contained in the polymer is stoichiometrically reduced from 30% to 100% by a basic substance.
%, preferably 60% to 100%, particularly preferably 8
It is sufficient to neutralize 0% to 100%.

Basic substances used for neutralization include, for example, ammonia and ammonium hydroxide, ammonium salts such as phosphates, acetates, carbonates, bicarbonates, etc., which dissolve in water and act as a base, and organic amines. or derivatives thereof such as mono-, di-, trimethylamine, ethylamines, isopropylamines, butylamines, ethanolamines, isopropanolamines, dimethylaminoethanol, diethylaminoethanol,
These include monomethylaminoethanol, monoethylaminoethanol, dimethylaminoisopropanol, and diethylaminoisopropanol.

Examples of the self-emulsifying emulsion made of the above-mentioned copolymer applicable to the present invention include the "trade name: Zaixen" series commercially available from Sumitomo Seika Co., Ltd.

Furthermore, ethylene-α,β- used in the present invention
Copolymers of olefinic unsaturated carboxylic acids or salts thereof can also be used together with other compounds as coating compositions. These coating compositions are specifically disclosed in Japanese Patent Application Laid-Open No. 49-9472.
As disclosed in No. 5, (a) 1 to 40% by weight of a copolymer consisting of at least 50 mol% ethylene and at least 4 mol% α,β-ethylenically unsaturated carboxylic acid or ammonium salt thereof; (b) 0.5 to 50% by weight of methylolmelamine having at least two methylol groups in one molecule (c)
General formula R-O-R' (R in the formula represents an aliphatic hydrocarbon residue having 1 to 5 carbon atoms, R' is HCO-, RCO-
-, C6 H5 CO-) 0 to 60% by weight (d) 0 to 30% by weight of acrylate and acrylamide alone or as a mixture (e) The remainder is water and/or methanol, Ethanol, isopropanol, n-propanol, n-butanol, iso-butanol, ter-butanol, se
Examples include coating compositions comprising the above (a) to (e), which are at least one alcohol selected from c-butanol, iso-amyl alcohol, and n-amyl alcohol. The coating film obtained from the above coating composition has excellent coating hardness, water resistance, corrosion resistance, and further adhesion.

The copolymer used in the present invention can be produced by various methods, for example, by using a radical initiator such as dibenzoyl peroxide as a catalyst.
250℃, 1000kg/cm2 ~2000kg/c
It can also be obtained by copolymerizing ethylene and α,β-ethylenically unsaturated carboxylic acid within the range of m2.

The copolymer containing the ammonium salt of α,β-ethylenically unsaturated carboxylic acid used in the present invention is a copolymer containing ethylene and α,β-ethylenically unsaturated carboxylic acid obtained as described above. The polymer can be prepared at a temperature of at least 60°C, preferably 80°C or higher, in the presence of sufficient aqueous ammonia and water so that the copolymer forms a stable emulsion.

The amount of ammonia sufficient to transform the ethylene-α,β-ethylenically unsaturated carboxylic acid copolymer into a stable emulsion is at least 4 moles based on the total constituent monomer units of the copolymer. % or more, the ethylene unit content in the copolymer is at least 50 mol% or more.

α, which constitutes the copolymer used in the present invention,
As β-ethylenically unsaturated carboxylic acid, 3 carbon atoms
It is desirable to have ~8 atoms, examples of which are acrylic acid,
Monocarboxylic acids such as methacrylic acid and ethacrylic acid, itaconic acid, and maleic acid. These include dicarboxylic acids such as fumaric acid.

The copolymer used in the present invention does not necessarily have to be
It does not have to consist only of the above two components. The content of each unit of ethylene and α,β-ethylenically unsaturated carboxylic acid in this copolymer is at least 50 mol% and 4 mol%, respectively, but in addition to these two components, copolymerizable monomers may also be used. Examples of the additional copolymerizable monomers include esters of α,β-ethylenically unsaturated carboxylic acids such as methyl acrylate, ethyl acrylate, and methyl methacrylate, and vinyl formate, vinyl acetate, and vinyl propionate. There are carboxylic acid vinyl esters.

Among the constituent components (b) of the coating composition used in the present invention, methylolmelamine contains at least 2 methylolmelamines per molecule.
It is necessary to have methylol groups. Furthermore, methoxylated methylol groups can also be used.

The coating composition used in the present invention contains a predetermined amount of the above-mentioned copolymer of ethylene-α,β-ethylenically unsaturated carboxylic acid and/or its ammonium salt and methylolmelamine, and the remainder is water or alcohol. It can be obtained by adding and mixing by any method, but it is preferable and convenient to mix by high-speed stirring, for example, using a mixing tank such as a homogenizer.

[0025] To the coating composition prepared as above,
Further, the general formula R-O-R' (R in the formula represents an aliphatic hydrocarbon residue having 1 to 5 carbon atoms, R' is HCO-, RCO-
-, C6 H5 CO-) in an amount of 60% by weight or less, preferably 5 to 50% by weight, the wettability of the water-based paint to the object to be coated is significantly improved.

Examples of compounds represented by the general formula R-O-R' include formic acid esters such as methyl formate, ethyl formate, isopropyl formate, methyl acetate, ethyl acetate,
Examples include acetic acid esters such as isopropyl acetate, and benzoic acid esters such as methyl benzoate, ethyl benzoate, and isopropyl benzoate.

[0027] Regardless of whether or not the compound represented by R-O-R' is added, ammonium acrylate and acrylamide, alone or in combination, may be added to the coating composition specified above in an amount of not more than 30% by weight. amount, preferably 5~
By adding 20% by weight, the adhesion of the coating film to the object to be coated is significantly improved.

Ethylene-α applied to the present invention
Examples of coating compositions containing .

In the present invention, a copolymer of ethylene-α,β-ethylenically unsaturated carboxylic acid or a salt thereof, or a coating composition using the same, emits light together with a fluorescent material or a ferroelectric insulating material. forming a layer or an insulating layer.

The phosphor applied to the light-emitting layer may be a phosphor for an EL lamp, and although it is not limited, a zinc sulfide-based phosphor is usually used. It is recommended that these phosphors be coated with a water-resistant inorganic substance in advance for the purpose of further improving their water resistance.

[0031] Examples of such water-resistant inorganic substances include phosphates. Examples of these phosphates include phosphates made of at least one metal selected from magnesium, calcium, strontium, and barium, particularly phosphates made of magnesium and calcium metals, and these include phosphates made of at least one metal selected from magnesium, calcium, strontium, and barium. The average particle size of the phosphor is usually about 3 μm to about 6 μm, although it is not unique depending on the particle size, particle size distribution, etc.
If the thickness is in the range of 0 μm, the coating thickness may be from about 0.005 μm to about 1 μm. As a specific method for coating the phosphor with these phosphates, the method described in JP-A-1-315485 is used.

Water-resistant inorganic substances other than phosphates include at least one metal oxide such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, yttrium oxide, and zinc oxide, magnesium silicate, calcium silicate, and strontium silicate. and at least one alkaline earth silicate such as barium silicate, at least one inorganic polymer such as polyphosphoric acid, polyaluminum chloride, polysilicon oxide, polytitanium oxide, magnesium titanate, calcium titanate, barium titanate, At least one type of titanate such as lead titanate, barium strontium titanate, zirconium lead titanate, and lanthanum zirconium lead titanate can be mentioned. The coating thickness may be within the same range as the above phosphate.

The phosphor coated with the above-mentioned water-resistant inorganic substance can also be used by rapidly heating it by plasma treatment or the like to melt and solidify at least the surface of the coated substance in order to further improve its moisture resistance. Details of these processing methods are available in Japanese Patent Application No.
No. 304650 may be referred to.

On the other hand, the ferroelectric insulating material applied to the insulating layer is not particularly limited as long as it is used in EL lamps, but is usually barium titanate, barium strontium titanate, Examples include ferroelectric insulating materials mainly containing barium titanate, such as barium lead titanate and barium lead tin titanate.

In the present invention, a copolymer of ethylene-α,β-ethylenically unsaturated carboxylic acid or a salt thereof used as a matrix in an insulating layer or a light-emitting layer and a ferroelectric insulating substance or a fluorescent substance are combined. The mixing ratio is about 10 parts by weight to about 100 parts by weight in the case of the phosphor, preferably about 20 parts by weight to about 50 parts by weight in the case of the ferroelectric insulating material, to 10 parts by weight of the matrix-forming solid component. is about 10 parts by weight to about 200 parts by weight, preferably about 30 parts by weight to about 1 part by weight.
00 parts by weight.

The formation of these insulating layers and luminescent layers may be carried out by any method conventionally practiced in the field and is not particularly limited; The composition may be mixed in advance and made into a slurry or paste and applied onto the back electrode or plastic film.

Coating methods include spraying, dipping, pouring, brushing, bar coater, roll coater, spin coater, screen printing, knife coater, etc. After coating, the coating temperature is about 50°C to about 180°C, preferably. Approximately 80℃~
Alcohol or water is removed by drying or baking at about 150°C. As another drying method, a microwave oven is also effective.

In the present invention, the thickness of the insulating layer and the light-emitting layer is not particularly a substitute for that using a conventional matrix made of a cellulose material, and the thickness of the insulating layer is usually about 3 μm to about 30 μm, and the thickness of the light-emitting layer is about 10 μm to about 30 μm. Approximately 1
It is used in the range of 00 μm.

After forming the insulating layer and the light-emitting layer on the back electrode, a transparent electrode layer and, if necessary, a water-absorbing layer (water-trapping layer) are provided according to the method for forming a normal organic dispersion type EL lamp. By covering the entire structure with a moisture-proof film, an EL lamp with excellent moisture resistance can be obtained. The copolymer of ethylene-α,β-ethylenically unsaturated carboxylic acid or its salt used as the matrix, or the coating composition containing the same, has high adhesive strength and high waterproofness, so it is suitable for use as an insulating layer. Use as an adhesive or waterproof layer to bond a light-emitting layer, a light-emitting layer and a transparent electrode layer, a transparent electrode layer and a water-absorbing layer (water-absorbing layer), or a transparent electrode layer and a moisture-proof layer, and a transparent electrode and a back electrode. It is also possible to apply the same type of moisture-proof film to the sealing part of the moisture-proof film of the metal or metal-plated lead for conducting electricity to the EL lamp, or to apply it as a waterproofing agent to the edge of the sealing surface of the EL lamp. It is.

[0040]

Effects of the Invention: A copolymer made of ethylene-α,β-ethylenically unsaturated carboxylic acid or a salt thereof, or a paint containing the same in the luminescent layer and/or insulating layer of the present invention as detailed above. EL lamps using the composition have superior water resistance compared to conventional matrix-forming resins, so they can provide long-life EL lamps.Especially when used in the insulating layer, titanic acid The effect is particularly excellent, probably because it protects the ferroelectric insulating material that mainly contains barium and does not cause its hydrolytic deterioration.

Therefore, it exhibits much better moisture resistance than conventional EL lamps, so it can be used as a long-life EL lamp, for example, in backlights for CPU displays, panel lights for industrial equipment, and aircraft instruments. Panel lights, interior and exterior panel lights for automobiles, panel lights for ships, panel lights for snowmobiles or trains, panel lights for indoor and outdoor disaster prevention signs, decorative panel lights, etc., daily miscellaneous goods such as lighting toys, night lights, mood lamps, etc. It can be applied to all kinds of applications, and its industrial value is extremely large.

[0042]

[Example] The present invention will be explained in more detail with reference to Examples, which are intended to explain one embodiment of the present invention and are not intended to limit the invention in any way.

Example 1 105 parts by weight of commercially available barium titanate powder (particle size <3 μm)
) and ethylene-acrylic acid copolymer-based n-butanol dispersion coating composition [trade name: Zaixen A-TH (solid content 1
0%)/manufactured by Sumitomo Seika Co., Ltd.] were mixed and stirred to prepare a paint. The paint was applied onto an aluminum foil plate using a doctor blade method, dried at 110°C, and then completely dried in a microwave oven to form an insulating layer (thickness: 10 μm).
was formed.

Next, 15 parts by weight of a high dielectric constant cellulose resin (dielectric constant 28) and 4 parts by weight of dimethylformamide were added thereon.
5 parts by weight and 1% phosphate coated phosphor (average particle size 30 μm)
After mixing 40 parts by weight and coating by doctor blade method, drying at a temperature of 130°C for 10 minutes to form a phosphor layer (thickness 50 μm), ITO transparent electrodes were formed on it, and leads were attached to each electrode. An EL element (not encapsulated with a moisture-proof polychlorotrifluoroethylene film, hereinafter referred to as an unencapsulated EL element) was manufactured by attaching the EL element. The unencapsulated EL device obtained as described above was placed in a constant temperature and humidity chamber at a temperature of 25° C. and 40% RH, and was continuously lit at 115 V and 400 Hz to measure the half-life. As a result, the half-life was 715 hours.

Comparative Example 1 In Example 1, the ethylene-acrylic acid copolymer system n
- Insulating layer (thickness 20 μm) was formed. Thereafter, an unencapsulated EL element was manufactured in the same manner as in Example 1. The half-life of the unencapsulated EL device obtained as described above was measured in the same manner as in Example 1. As a result, the half-life is 2
It was 60 hours.

Example 2 An aqueous ethylene-acrylic acid copolymer solution was used as a light-emitting layer on an insulating layer formed in the same manner as in Comparative Example 1, instead of the dimethylformamide solution of high dielectric constant cellulose resin in Example 1. Unencapsulated E
An L element was manufactured. The half-life of the unencapsulated EL device obtained as described above was measured in the same manner as in Example 1. As a result, the half-life was 830 hours.

Example 3 An unencapsulated EL device was manufactured in the same manner as in Example 1, except that a light-emitting layer was formed in the same manner as in Example 2 on the insulating layer formed in the same manner as in Comparative Example 1. Unencapsulated EL obtained as above
The half-life of the device was measured in the same manner as in Example 1. As a result, the half-life was 1000 hours.

Example 4 An ethylene-acrylic acid copolymer-based alcoholic paint [trade name: Zaixen A-TH/n-butanol dispersed emulsion (solid content 5%)] was applied on an insulating layer formed in the same manner as in Comparative Example 1. manufactured by Sumitomo Seika Co., Ltd.] by a doctor blade method and dried at 100° C. for 10 minutes to form a coating film with a thickness of about 3 μm. In this manner, an ethylene-acrylic acid copolymer waterproof coating was formed on the insulating layer, and then a light-emitting layer, an ITO transparent electrode, and a lead were provided in the same manner as in Example 1, and an unencapsulated EL element was formed. was produced. The half-life of the unencapsulated EL device obtained as described above was measured in the same manner as in Example 1. As a result, the half-life was 850 hours.

Claims (1)

[Claims] Claim 1. An organic dispersed electroluminescent lamp using an organic polymer matrix as a light-emitting layer and/or an insulating layer, in which the organic polymer matrix contains 50
At least 3% by weight of ethylene, 3 to 50% by weight of α,β-olefinic unsaturated carboxylic acid or its salt, and 0 to 40% by weight of α,β-olefinic unsaturated carboxylic acid or salt thereof
A moisture-resistant electroluminescent lamp characterized in that it uses a copolymer of ethylene-α,β-olefinic unsaturated carboxylic acid or a salt thereof, which is obtained by copolymerizing % by weight of a vinyl group-containing compound.