JP3277965B2 - Electroluminescence panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescent panel. More specifically, the present invention relates to an electroluminescent panel having high luminance and excellent durability.

[0002]

2. Description of the Related Art Electroluminescent panels (hereinafter referred to as EL panels) are used for various applications such as various displays and backlights of liquid crystals.
Conventional EL panels are made by printing a dielectric layer on one side of a metal plate such as aluminum, printing a phosphor layer thereon, and then thermocompressing a transparent conductive film thereon. .

[0003] Phosphor substances such as zinc sulfide contained in the phosphor layer are remarkably deteriorated by moisture absorption, so that the durability of the conventional EL panel is poor. In order to prevent such deterioration due to moisture absorption, a method of covering a transparent conductive film with a moisture-proof film has been used. As a moisture-proof film, for example, on a trifluorinated ethylene film,
Ethylene-vinyl acetate copolymer (hereinafter referred to as EVA)
Such a film having an adhesive layer is used. However, since this moisture-proof film has a low light transmittance, it has a drawback that the luminance (hereinafter, referred to as initial luminance) when the EL panel is started to be used becomes low. Although there is a method of coating with a gas barrier film using a silicon oxide thin film, it is not colorless and transparent but has a brownish color, so that the initial luminance is low and there is a problem in durability. For these reasons, there is a demand for the development of an EL panel which has little decrease in luminance and has excellent durability.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide an EL panel having high luminance and excellent durability.

[0005]

SUMMARY OF THE INVENTION The present inventors have developed an electroluminescent panel having a specific coating film.

The electroluminescent panel according to the present invention is an electroluminescent panel including a laminate in which a dielectric layer, a phosphor layer, and a transparent conductive film are sequentially formed on a conductive plate. The whole is covered with a coating film having an oxide thin film composed of silicon oxide and at least one other oxide on at least one surface of a transparent plastic substrate, thereby achieving the above object.

[0007] In a preferred embodiment, the specific gravity of the oxide thin film of the coating film is 55 to 100% with respect to the specific gravity of the oxide in a crystalline state.

The conductive plate used in the present invention includes a plate made of metal such as aluminum, copper, silver, and gold. Since the conductive plate is used as an electrode, any conductive material may be used. There is no particular limitation. The conductive plate also
For the purpose of preventing deterioration such as oxidation and improving the adhesiveness, a surface treatment or coating may be applied as long as the conductivity is not impaired.

The dielectric layer formed on the conductive plate contains barium titanate as a main component. In addition to barium titanate and the like, other dielectrics such as strontium titanate, lead titanate, hafnium oxide, aluminum oxide, tantalum oxide, and silicon oxide may be contained. The method for forming the dielectric layer on the conductive plate is not particularly limited. For example, barium titanate or a powder of a dielectric mainly composed of barium titanate is dispersed in a high-dielectric resin by a known method. There is a method of printing this on the conductive plate by a known method such as screen printing or roll coating. The thickness of the dielectric layer is preferably 5 to 8 μm,
More preferably, it is 0 μm.

The phosphor contained in the phosphor layer used in the present invention contains zinc sulfide as a main component, and other phosphors may be contained in an amount that does not change the properties of the phosphor layer. The phosphor layer may contain an additive. The method of forming the phosphor layer on the dielectric layer is not particularly limited,
For example, in the high dielectric resin used to form the dielectric layer, a phosphor powder such as zinc sulfide is dispersed by a known method, and this is dispersed by a known method such as screen printing or roll coating. There is a method of printing on a dielectric layer. The thickness of the phosphor layer is preferably from 8 to 300 μm, more preferably from 20 to 100 μm.

The powder of barium titanate, zinc sulfide or the like used in the dielectric layer and the phosphor layer may be subjected to a surface treatment or the like as long as the purpose is not impaired.
Examples of the high dielectric resin used for the dielectric layer and the phosphor layer include cyanoethyl cellulose and the like. Ethylene glycol monomethyl ether, tetrahydrofuran, methyl ethyl ketone, acetonitrile, furfuryl alcohol, methyl acetoacetate, nitromethane, N, N- Dimethylformamide, N-methyl-2-
It is used by dissolving in pyrrolidone, acetone, cyclohexanone and the like.

The transparent conductive film used in the present invention is a film having a single-layer or multi-layer transparent thin film containing a conductive substance on at least one entire surface or a part of a transparent plastic sheet. Examples of the transparent plastic sheet include sheets made of polyester, polyether sulfone, polycarbonate, polystyrene, and the like. Examples of the conductive substance include indium oxide, tin oxide, indium tin oxide, gold, silver, and palladium. To form a transparent thin film containing such a conductive substance on a transparent plastic sheet,
Examples include methods such as sputtering, vacuum deposition, ion plating, and coating. The method of bonding this transparent conductive film to the phosphor layer is not particularly limited,
Known thermocompression bonding methods, such as heat press and roll lamination, are mentioned.

The coating film used in the present invention includes:
This is a film in which an oxide thin film composed of silicon oxide and at least one other oxide is formed on at least one surface of a plastic substrate.

The above-mentioned plastic substrate refers to a film obtained by melt-extruding an organic polymer, stretching the polymer in the longitudinal direction and / or the width direction as required, cooling, and then heat-setting. As organic polymers, polyethylene, polypropylene, polyethylene terephthalate,
Examples thereof include polyethylene-2,6-naphthalate, nylon 6, nylon 4, nylon 66, polyamide imide, polyimide, polyether imide, polycarbonate, polystyrene, polyether sulfone, and all kinds of aromatic polyamide. These organic polymers can be used alone, but those obtained by copolymerizing or blending two or more kinds little by little can also be used. Further, known additives such as an ultraviolet absorber, an antistatic agent, a plasticizer, a lubricant, and a coloring agent may be added to the organic polymer. As long as the object of the present invention is not impaired, the plastic substrate is subjected to a surface roughening treatment such as a corona discharge treatment, a glow discharge treatment, and an anchor before forming an oxide thin film on the substrate. Coating, printing, decoration, etc. may be performed. The thickness of the plastic substrate is 10
It is preferably in the range of 250 μm.

The oxide thin film contains silicon oxide and at least one other oxide other than silicon oxide. Silicon oxide is preferably contained at 10% or more, more preferably at least 20%. The oxide other than silicon oxide refers to a compound of a metal, a semiconductor or a nonmetal other than silicon, and oxygen, for example, aluminum oxide, magnesium oxide, calcium oxide, boron oxide, zirconium oxide, titanium oxide, Zinc oxide, strontium oxide, barium oxide,
It refers to hafnium oxide and the like, and is not particularly limited thereto.

In order to form the oxide thin film on the surface of the transparent plastic substrate, a vacuum evaporation method, a sputtering method, a PVD method (physical vapor deposition method) such as ion plating, a CVD method (chemical vapor deposition method) or the like is appropriately used. Can be For example, in a vacuum deposition method, SiO ₂ or S
i, SiO ₂ , a mixture of SiO, and a metal, a non-metal or a semiconductor to be contained in a thin film, or an oxide thereof are used, and resistance heating, high-frequency induction heating,
Heated by electron beam heating or the like. Examples of the reactive gas used in this method include oxygen, nitrogen, and water vapor.Instead of introducing these gases, ozone addition and reactive deposition using means such as ion assist may be performed. Good. In this method, a bias may be applied to the substrate, or the temperature of the substrate may be increased or cooled, as long as the object of the present invention is not impaired. The production conditions can be similarly changed in other production methods such as a sputtering method and a CVD method.

The substrate film on which the oxide thin film is formed may be used as it is as a coating film, but a film or thin layer of another organic polymer is laminated or coated on the surface of the oxide thin film. You may use it.

The specific gravity of the oxide thin film is more preferably 55 to 100% with respect to the specific gravity of the oxide in a crystalline state. The specific gravity of the thin film is 5 times the specific gravity of the crystalline oxide.
If it is less than 5%, the structure of the oxide thin film containing silicon oxide becomes coarse, and sufficient gas barrier properties cannot be obtained.
It is practically difficult to produce a thin film in which the specific gravity of the thin film is greater than 100% of the specific gravity of the oxide. For the above reasons, the specific gravity of the oxide thin film preferable as the coating film is preferably 55 to 100%, more preferably 65 to 100%, relative to the specific gravity of the oxide in a crystalline state.

The specific gravity used in the present invention refers to the ratio of the mass of a substance occupying a certain volume at a certain temperature to the mass of a standard substance having the same volume (water at 4 ° C.). The measurement of specific gravity is
Normally, the mass and volume of the object may be measured and the ratio of the mass of the same volume of water at 4 ° C. may be obtained. However, in the present invention, it is difficult to measure the volume of the thin film. Therefore, first, a thin film is peeled off from the base material, or only the base material is dissolved to form a single film consisting of only the thin film.
It is desirable to perform specific gravity measurement according to 112. For example, in the float-sink method, a sample is immersed in a solution having a known specific gravity, and the specific gravity of the thin film can be measured from the float-sink state. As this solution, a mixed solution of carbon tetrachloride and bromoform, a mixed solution of carbon tetrachloride and methylene iodide, and the like can be used. Alternatively, the specific gravity value can be measured by a density gradient piping method in which a single film is immersed in a solution having a continuous density gradient.

The specific gravity of the oxide in the crystalline state refers to the ratio of the mass of the oxide in the crystalline state to the mass of a standard substance (water at 4 ° C.) having the same volume as that of the oxide in the crystalline state. Refers to the specific gravity of an object. Depending on the oxide, it may have any number of crystal forms, but the specific gravity of a crystal generally present at normal temperature and normal pressure is representative. For example, in silicon oxide, 2.65 of quartz and in aluminum oxide, α-Al
It is 3.97 for ₂ O ₃ and 3.65 for magnesium oxide. In the case of a mixture or compound of two or more oxides (hereinafter, referred to as a composite oxide), the specific gravity of the oxide is calculated as a mixture of unit oxides. Here, the unit oxide means each oxide constituting the composite oxide. For example, the unit oxide of the Al ₂ O ₃ —SiO ₂ composite oxide is A
a l ₂ O ₃ and SiO _2, ZrO ₂ -MgO-SiO
₂ The unit oxide of the composite oxide is ZrO ₂ , MgO and S
iO ₂ . Here, the specific gravity of the composite oxide is calculated from the specific gravity and the ratio of the unit oxide, and the specific gravity of the unit oxide is A ₁ ,
A ₂ , A ₃ , A ₄ ,... And their ratios are a ₁ , a ₂ , a ₃ ,
Assuming that a ₄ ,..., the specific gravity Z of the composite oxide is represented by Z = A ₁ a ₁ + A ₂ a ₂ + A ₃ a ₃ + A ₄ a ₄ +.

To manufacture the EL panel of the present invention, first, the dielectric layer is formed on the conductive plate by screen printing, roll coating, or the like, and then the phosphor layer is formed on the dielectric layer in the same manner. To form Next, an electrode is printed on the end of the conductive surface of the transparent conductive film with a silver paste or the like, and then the conductive surface and the phosphor layer surface are adhered by roll lamination or the like, thereby bonding the transparent conductive film to the phosphor layer. Laminate on top. An EL panel can be obtained by covering the entire laminate thus obtained with the above-mentioned coating film and, if necessary, the moisture-proof film.

Next, an embodiment will be described.

[0023]

EXAMPLES The measuring methods used in this example and comparative examples are described below.

(1) Luminance Colorimeter (“Minolta Camera Co., Ltd.” CS-100)
The distance between the EL panel and the measuring instrument was 1.5 m, the measurement angle was 1 degree, the measurement time was 1.6 seconds, and JIS C
It was measured according to 7614. The luminance is a luminous intensity (cd) per 1 m ² of the light emitting surface, and 1 cd / m ² = 1 nit. The unit “nit” is described as “nt”.

(2) Durability The EL panel was continuously lit at 500 Hz and 110 V at 70 ° C. (under drying), and the luminance after 100 hours, 200 hours, and 300 hours was measured by the above method. Was examined for decline.

(Example 1) An aluminum plate having a thickness of 100 μm and alumite-treated on one side (manufactured by Tokai Aluminum Foil)
A dielectric layer, a phosphor layer, and a transparent conductive film were sequentially laminated on the alumite-treated surface of No. 1 to obtain a laminate. The dielectric layer is formed by dissolving cyanoresin (manufactured by Shin-Etsu Chemical Co., Ltd.) in dimethylformamide (25% by weight) to prepare a binder, and then using the same weight of barium titanate (manufactured by Fuji Titanium Industry Co., Ltd., BT) -100P) was dispersed in a binder, printed using a # 200 stainless steel screen, and then dried at 120 ° C. for 10 minutes to form an alumite-treated surface of an aluminum plate. The phosphor layer is made of the same weight of zinc sulfide powder (manufactured by Sylvania, TYPE 81) in a binder similar to the binder used for the dielectric layer.
3) was formed by dispersing and printing it on the dielectric layer using the same stainless screen as described above. Transparent conductive film (Toyobo Co., Ltd., 300L)
Print electrodes with silver paste on the end of the conductive surface of
The transparent conductive film was laminated on the phosphor layer by bonding the conductive surface and the phosphor layer surface by roll lamination. The laminating conditions were a roll temperature of 180 ° C., a laminating speed of 10 cm / min, and a laminating pressure of 10 kg / cm.

The thus obtained laminate is laminated on a polyethylene terephthalate film (hereinafter referred to as PET film) (75 μm thick) with a coating film obtained by depositing an Al ₂ O ₃ —SiO ₂ thin film on the polyethylene terephthalate film (thickness: 75 μm). This was sandwiched with an EVA-based adhesive sheet (manufactured by Mitsui Petrochemical Co., Ltd., VE300) by heating and pressing to cover the EL sheet.

The film for coating is made of Al as an evaporation source.
It was formed by vapor deposition on one side of a 75 μm thick PET film using ₂ O ₃ and SiO ₂ by an electron beam vapor deposition apparatus. Using an electron beam gun (hereinafter, referred to as an EB gun) as a heating source, Al ₂ O ₃ and SiO ₂
Each was heated separately. At that time, the emission current of the EB gun was 1.2 to 2.0 A, and Al ₂ O ₃
And the heating time ratio of SiO ₂ is 30:10, and the composition ratio of the transparent thin film obtained is Al ₂ O ₃ : SiO ₂ = 60: 4.
It was set to 0. The vapor pressure during deposition is 3 × 10 ^-4 T
orr to 5 × 10 ⁻³ Torr. Thus P
The thickness of the thin film obtained on the ET film was 600 Å. The specific gravity of this thin film was measured by dissolving a PET film as a base material and using a float-sink method. As a result, the specific gravity of the thin film was 2.68, which was 78% of the specific gravity of the oxide in a crystalline state containing 40% of silicon oxide, 3.44.

The luminance durability of the EL panel thus obtained was measured, and the results are shown in Table 1. Example 2
Table 1 also shows the results of Comparative Example 4 and Comparative Examples 1 to 3.

(Example 2) An EL panel was manufactured in the same manner as in Example 1. However, the specific gravity of the thin film of the obtained coated film was 1.72, which was 50% with respect to the specific gravity of the crystalline oxide containing silicon oxide of 40% of 3.44. The durability of the luminance of the EL panel thus obtained was measured.

[0031] except that the oxide thin film (Example 3) coated film was MgO-SiO ₂ thin film, to produce an EL panel in the same manner as in Example 1. The coating film,
It was formed by using MgO and SiO ₂ as a vapor deposition source and vapor-depositing on one side of a PET film having a thickness of 75 μm by an electron beam vapor deposition apparatus. EB as heating source
Using a gun, each of the MgO and SiO ₂ was heated separately. The emission current of the EB gun at that time is as follows.
The heating time ratio of MgO and SiO ₂ was 30:10, and the composition ratio of the transparent thin film obtained was MgO: SiO ₂ = 25: 75. The vapor pressure at the time of vapor deposition is 3 × 10 ⁻⁴ Torr to 5 × 10 ⁻³ To.
rr. The thickness of the thin film thus obtained on the PET film was 400 Å. The specific gravity of this thin film was measured by dissolving a PET film as a base material and using a float-sink method. As a result, the specific gravity of the thin film was 1.97, which was 68% of the specific gravity of an oxide containing 75% of silicon oxide of 2.90.
Met. The durability of the luminance of the EL panel thus obtained was measured.

Example 4 An EL panel was manufactured in the same manner as in Example 3. However, the specific gravity of the thin film of the obtained coated film was 1.45, which was 50% with respect to the specific gravity of an oxide containing 75% of silicon oxide of 2.90. The durability of the luminance of the EL panel thus obtained was measured.

(Comparative Example 1) Example 1 was repeated except that the coating film and the EVA-based adhesive sheet were not used.
In the same manner as in the above, an EL panel was produced, and the luminance durability of the obtained EL panel was measured. As is clear from Table 1, the obtained EL panel was inferior in durability.

(Comparative Example 2) The procedure was carried out except that the coating was carried out under the following conditions using an ethylene trifluoride chloride film (manufactured by Nitto Denko) instead of the coating film and the EVA-based adhesive sheet. An EL panel was manufactured in the same manner as in Example 1. Two pieces of the above ethylene chloride trifluoride film,
The laminate was press-bonded to both sides of the laminate by heating and pressing at 5 kg / cm ² for 5 minutes with a press at 120 ° C. E obtained
When the durability of the L panel was measured by the above method,
Even after 00 hours, the brightness was maintained as high as 30 nt, but the initial brightness was inferior to that of the above embodiment, and was not suitable for practical use.

Comparative Example 3 A thin film of Al ₂ O ₃ —SiO ₂ was prepared using P
Instead of a coating film deposited on an ET film,
An EL panel was obtained in the same manner as in Example 1 except that a coating film obtained by evaporating a thin film consisting only of silicon oxide on a PET film as follows was used.

The above-mentioned coated film is made of SiO as an evaporation source.
Was formed by vapor deposition on one side of a PET film having a thickness of 75 μm using an electron beam vapor deposition apparatus.
An EB gun was used as a heating source. At that time, the emission current of the EB gun was set at 1.3 A, and the obtained transparent thin film was made of SiO _1.5 . The vapor pressure during evaporation is 3
× 10 ⁻⁴ Torr to 5 × 10 ⁻³ Torr. The thickness of the thin film thus obtained on the PET film is 40
It was 0 angstroms. The specific gravity of the thin film of the obtained coated film was 1.85, which was 70% with respect to the specific gravity of the oxide, 2.65. The obtained EL panel was inferior in both the initial luminance and the durability as compared with the above-mentioned example.

[0037]

[Table 1]

[0038]

According to the present invention, it is possible to provide an electroluminescent panel having high luminance and excellent durability.

Continued on the front page (72) Inventor Shigetsuji Yamaguchi 2-1-1 Katata, Otsu-shi, Shiga Prefecture Toyobo Co., Ltd. Film Technology Center (72) Inventor Hideo Miyake 2-2-8 Dojimahama, Kita-ku, Osaka-shi, Osaka East (56) References JP-A-3-283291 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 33/04

Claims (2)

(57) [Claims] 1. A laminate comprising a conductive plate, on which a dielectric layer, a phosphor layer, and a transparent conductive film are sequentially formed.
An electroluminescent panel, wherein the laminate is entirely coated with a coating film having an oxide thin film including silicon oxide and at least one other oxide on at least one surface of a transparent plastic substrate, Electroluminescence panel. 2. The electroluminescent panel according to claim 1, wherein a specific gravity of the oxide thin film of the coating film is 55 to 100% with respect to a specific gravity of the oxide in a crystalline state.