JPH02192691A - El luminous element - Google Patents

Abstract

PURPOSE:To prevent the generation of a bend in the sealing process and to improve a poor luminescence under a high temperature and a high humidity condition by including a protective layer which consists of a specific biaxial extension high polymer film, a dampproof layer which consists of a metal membrane or the like, and a sealant layer, in the composition of a back side dampproof sealing material. CONSTITUTION:A diffusion type electroluminescence luminous element (EL luminous element) consists of a surface dampproof sealing material 11, a transparent surface electrode, a luminous layer 7, a back electrode 5, a lead electrode 12, and a back side dampproof sealing material 2. The structure of the back side dampproof sealing material 2 includes a protective layer 1 which consists of a biaxial extension high polymer film in which the mean contraction rate in the film length direction (MD) and the film width direction (TD) when heating from the outside of the element at 110 deg.C in order is one % or more, a dampproof layer 2 which consists of a metal membrane or a metal foil, and a sealant layer 4. As a result, a bending to the luminous surface side in the sealing process and in a normal temperature can be prevented, and a poor luminescence in a high temperature and a high humidity condition can be improved.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a distributed electroluminescence light emitting device (
Hereinafter, it will be abbreviated as an EL light emitting element. ), for more details,
The present invention relates to an EL light emitting device using a composite film of a polymer film having a specific heat shrinkability and a metal thin film or metal foil as a component of a back moisture-proof sealing material.

(Prior Art) Generally, an EL light-emitting element includes a front electrode made of a transparent conductive film, a luminescent layer made of a highly dielectric binder and a fine luminescent powder, an optional reflective insulating layer made of a highly dielectric substance, and a back surface. It has a structure in which electrodes are laminated in this order, and the outside of this is sealed with a moisture-proof sealing material on the front and back surfaces, so that it is possible to conduct an alternating current electric field between the front and back electrodes or between the two conductors. By applying this, so-called electroluminescence can be obtained.

However, the lifespan of EL light emitting elements is greatly affected by moisture. For this reason, excellent moisture-proof materials are needed, and conventionally polychlorotrifluoroethylene (hereinafter abbreviated as PCTFE) has been used as a moisture-proof sealing material for the front and back sides, and as a component of moisture-proof sealing materials for the back side. A composite film with metal foil such as aluminum foil is used.

An example of the latter is Japanese Patent Publication No. 60-41437.

In this publication, for example, the front moisture-proof sealing material is PCTFE with a sealant layer, the back moisture-proof sealing material is PET as a protective layer, A1 foil as the moisture-proof layer, and PCTFE as the insulating layer.
ET, a composite film composed of EVA as a sealant layer (PET 25μ/AI 20μ/PET 51
1/EVA 80μ).

(Problems to be Solved by the Invention) However, in the case of the former PCTFE, there is a problem of warpage in the appearance of the EL light emitting element, and there are disadvantages such as inferior commercial value and high cost. Furthermore, as a specific method of using the E1 light-emitting element, for example, when it is attached to a liquid crystal module and used as a backlight for the liquid crystal, if the EL light-emitting element is even slightly warped, it will of course be difficult to work with when installing it. Furthermore, there is a problem that the circuit of the liquid crystal module is easily damaged.

In addition, the EL light-emitting device using the latter composite film also has warpage in appearance, similar to the former case of PCTFE, and when left in high temperature, it becomes further deformed, and eventually the light-emitting layer/ITO/PET interface peels off. This has an extremely serious drawback in practical terms, in that EL light emission cannot be obtained due to this.

In other words, although the structure of Japanese Patent Publication No. 60-41437 achieves the objectives of being inexpensive and having excellent moisture resistance,
This structure is still inadequate because it does not take into account the extremely important factor for practical use, which is to prevent warpage of the device.

(Means for Solving the Problems) As a result of intensive studies to solve the above-mentioned problems, the present inventors discovered that a polymer film having a specific heat-shrinkability and a metal as a constituent component of a moisture-proof sealing material on the back surface. The present invention was achieved by discovering that by using a thin film or a composite film with metal foil, warping in appearance does not occur during sealing, and poor light emission under high temperature and high humidity is also improved.

That is, the present invention provides at least a surface moisture-proof encapsulation in a dispersed electroluminescent light-emitting device comprising a transparent surface electrode, a light-emitting layer, a back electrode, a LEET electrode, and a back moisture-proof sealing material. M when the composition of the encapsulating material is heated to 110°C sequentially from the outside of the element.
D, a distributed electroluminescence light-emitting element comprising at least a protective layer made of a biaxially stretched polymer film with a TD average thermal shrinkage rate of 1% or more, a moisture-proof layer made of a metal thin film or metal foil, and a sealant layer. be.

In addition, the following value is adopted as the value of the heat shrinkage rate in this invention.

Thermal shrinkage rate measurement method 10 with a sunbrink of 100 mm in the film width direction (T D) and 100 mm in the film length direction (MD)
0x 100 mm of each fillet in the oven (11
0°C) for 10 minutes, then take it out and leave it at room temperature (20°C).
Measure the length of the film when it is cooled to ℃), calculate the heat shrinkage rate (%) in the TD force direction and MD force direction from the dimensions of the film before and after treatment using the following formulas, and further calculate the heat shrinkage rate (%) in the TDh direction and the MO force direction. The average value is defined as MD and TD average thermal shrinkage rate (%).

In the present invention, the EL light emitting element main body and front moisture-proof sealing material are not particularly limited, and for example, conventionally known materials can be used.

More specifically, the biaxially stretched polymer film J having a specific heat shrinkability used for the protective layer of the back moisture-proof sealing material of the present invention will be described in more detail. For example, a polymer film having a heat shrinkage rate of 1% or more, more preferably 1 to 10%, most preferably 1 to 3%. Examples include stretched films of polyethylene, nylon 6, polyester, etc. that satisfy these conditions.

If a polymer film with a heat shrinkage rate of less than 1% is used, warping will occur on the light emitting surface side during sealing, and the warping prevention function will be insufficient even at room temperature, which will not meet the purpose of the present invention.

On the other hand, in the E1 light-emitting element using a stretched film with a high thermal shrinkage rate, the warpage prevention function during sealing and at room temperature is sufficiently satisfied by adjusting the thickness of the film, but at high temperatures, for example at 60°C. Under high temperatures, the adjustment of the thickness of the film becomes delicate and warping may occur on the back side, so it is possible to prevent warping on the back side without being affected by the thickness of the film even at high temperatures. In order to fully express its functions,
Those with a heat shrinkage rate of 1 to 10% are preferred, and those with a heat shrinkage rate of 1 to 3% are most preferred C).

In addition, the thickness of the protective layer is approximately 5 mm from the viewpoint of moisture resistance.
It is desirable that it is 0 μ or more.

As the metal thin film or metal foil formed by vapor deposition, sputtering, or ion blating method for the purpose of moisture proofing in the composite film of the present invention, conventionally known ones are used, such as AI, Zn, Cu, Cr, tli-Cr
etc.

In the case of metal foil such as aluminum foil, its thickness is usually 5μ or more,
Preferably, the thickness is 10μ or more, and up to about 100μ, and the protective layer is not particularly limited as long as it satisfies the above-mentioned heat shrinkage rate.

However, in the case of a metal thin film, in a composite film with a moisture-proof layer provided as a protective layer, moisture permeability is 0 from the viewpoint of moisture-proofing.
．． 5 g-mm/m2・24 hr or less (40°
C190%RH), more preferably 0.2 g-mm/m
2.24 hours or less is desirable. The thickness of the metal thin film is approximately 200λ to 5μ. If the film thickness is too thin, the moisture resistance will decrease, and if the film thickness is too thick, the heat damage to the film during film formation will increase, resulting in deformation of the film, etc. Undesirable. Also, the metal thin film may be one layer, but
A multilayer structure formed by dry lamination or the like with an insulating layer interposed therebetween may also be used.

Furthermore, in consideration of insulation and moisture absorption from the edges, a composite film may be obtained by providing a film with low moisture absorption, such as polypropylene, polyethylene, or vinylidene chloride, as an insulating layer between the moisture-proof layer and the sealant layer.

In addition to the above composite film, the ethylene content is 90% to 98%.
A conventionally known sealant layer such as EVA (about 10%) is provided as a moisture-proof sealing material on the back side, and the element body is sealed (see FIG. 2).

(Effects of the Invention) By using the composite film of the present invention as a component of the back moisture-proof sealing material, warping toward the light emitting surface side during sealing and at room temperature, which could not be achieved with conventionally known EL light emitting device configurations, can be achieved.
Furthermore, the problem of poor light emission at high temperatures can be solved, and its practical value is extremely great.

<Examples> Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

The following methods were used to measure the warpage of the light-emitting element and the moisture permeability of the moisture-proof composite film provided with the moisture-proof layer as the protective layer.

Method for Measuring Warpage For 10 samples, an arbitrary point on each element was pressed, and the floating height/distance from the fulcrum was determined, and the average value of the 10 samples was shown.

Moisture permeability measurement method According to the method described in JIS 20208, 40°C1
It was determined under 90% RH.

In addition, in the examples, E
An L light-emitting element body and surface moisture-proof sealing material were used.

Preparation of E1 light-emitting element body A paste consisting of 15 parts by weight of BaTiO3 powder, 8 parts by weight of cyanoethylated polyvinyl alcohol, and 6 parts by weight of N,N-dimethylacetamide was placed on the back electrode 5 made of A foil with a thickness of 80 μm after drying. A reflective insulating layer 6 is formed to have a thickness of 20 μm, and a ZnS layer is further formed on the insulating layer 6.
; A light-emitting layer 7 was formed using a paste consisting of 30 parts by weight of Cu, CI phosphor powder, 10 parts by weight of cyanoethylated polyvinyl alcohol, and 9 parts by weight of N,N-dimethylacetamide so that the film thickness after drying was 40 μm. . next,
The ITO surfaces of a front transparent electrode made of a transparent conductive layer 8 made of an ITO-coated polyester film and a transparent conductive layer base material 9 are pressed onto the surface of the light emitting layer 7 so as to face each other, and lead terminals 12 are attached to the front electrode and back electrode 5. Attach the 9cm
It was cut into a size of x5 cm to produce an EL light emitting device body.

Preparation of surface moisture-proof sealing material P with a thickness of 200) 1 as the surface moisture-proof sealing material base material 11
30 using CTFE film as the sealant layer 10
Tri-laminated μ EVA was used as a surface moisture-proof sealing material.

Example 1 In FIG. 1, l represents a biaxially stretched polymer film MD.
, TD average heat shrinkage rate 1.07% (MD direction 1.15%,
TD direction 0.98%) 200μ polyethylene, 2 is a 20μ A1 foil as a metal foil with moisture proofing, 3
4 is a 25 μm polypropylene which particularly prevents short circuits of the lead electrodes and also prevents moisture absorption from the ends, and 4 is a 3011 EVA as a sealant.

Using the tri-laminated composite film with the above configuration, an EL light emitting device was fabricated as a back moisture-proof sealing material as shown in FIG.

Example 2 In Fig. 1, 1 is MD, TD average heat shrinkage rate 2.64%
(2.75% in MD direction, 2.25% in TD direction) 200
μ nylon 6, 2 is 20μ A1 foil, 3 is 25
4 is 30μ EVA.

An EL light emitting device was produced in the same manner as in Example 1 using the composite film dry laminated with the above configuration.

Example 3 As shown in Fig. 1, 1 is a heat-shrinkable polymer film of 200 μm with an average MD and TD heat shrinkage rate of 7.19% (7.35% in MD direction, 7.02% in TD direction). polyethylene terephthalate (1) E T ), and 2
is 20μ A1 foil, 3 is 25μ polypropylene, and 4 is 30μ EVA with Sealan I.

An EL light emitting device was produced in the same manner as in Example 1 using the tri-laminated composite film with the above configuration.

Comparative Example 1 In Fig. 1, 1 indicates MD, TD average heat shrinkage rate 0, 05
% (MD direction 0.1%, TD direction 0%) 25μ unstretched PET, 2 is 20μ A1 foil, 3 is 25μ PET
, %4 is 80μ EVA.

An El-light emitting device was produced in the same manner as in Example 1 using the tri-laminated composite film with the above configuration.

Comparative Example 2 As a measure to prevent warping in Comparative Example 1, 30μ of E was added as a sealant between the AI back electrode and the back moisture-proof sealant.
An EL light emitting device was produced in the same manner as in Comparative Example 1 except that a 200 μm polyethylene film made of VA was provided.

Comparative Example 3 As shown in Fig. 1, 1 is MD, T [l average thermal shrinkage rate 0
．． 97% (MD direction 0.98%, TD direction 0.95%)
, polyethylene with a film thickness of 200 μm, 2 is A1 foil with a film thickness of 20 μm having moisture-proof properties, 3 is polypropylene with a film thickness of 25 μm to prevent leakage (especially in the lead terminal), and 4 is a film as a sealant. It is EVA with a thickness of 3゜μ.

A composite film dry-laminated with the above structure was used as a moisture-proof sealing material on the back surface, and a vibrating light emitting device was produced in the same manner as in Example 1.

Example 4 As shown in Fig. 1, 1 is a polymer film with shrinkability, MO, TD average thermal shrinkage rate 1.07% (MD direction 1, 15%, TD direction 0.98%), film thickness. 200μ polyethylene, 2 has moisture-proof film thickness 0.1μ
3 is a polyester film with a thickness of 12μ to prevent short circuits of the lead terminal, and 4 is an EVA film with a thickness of 30μ as a sealant.

An EL light emitting device was produced in the same manner as in Example 1 using the composite film dry laminated with the above configuration as a back moisture-proof sealing material.

Example 5 As shown in FIG. 3, 1 is a shrinkable polymer film with an average heat shrinkage rate of 1.07% in MD and TD (1.15% in MD direction, 0.98% in TD direction), and film J. 2 is polyethylene with a thickness of 200μ, and 2 has a moisture-proof film thickness of 0.1μ.
3 is a polypropylene film with a thickness of 25 μm to prevent short circuits of the lead terminal, 4 is an EVA film with a thickness of 30 μm as a sealant, and a moisture-proof layer 2.
and insulating layer 3 are each provided in three layers.

A light-emitting element was fabricated in the same manner as in Example 1 using the tri-laminated composite film with the above configuration as a back moisture-proof sealing material.

Example 6 As shown in FIG. 5, 1 is a shrinkable polymer film with an average MD and TD heat shrinkage rate of 7.19% (7.35% in the MO direction, 7.02% in the TO direction), and a film thickness. 2 is polyethylene with a thickness of 200μ, 2 is an AI vapor-deposited film with a thickness of 0.1μ and has moisture-proof properties, 3 is a polypropylene with a thickness of 25μ to especially prevent short circuits of the lead terminals, and 4 is a film with a thickness of 30μ as a sealant. This is E■A.

An EL light-emitting device was produced in the same manner as in Example 1 using a tri-laminated composite film with the following two configurations as a moisture-proof sealing material on the back surface.

Ten EL devices obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were heated at 25°C, 60% RH, and 60°C.

It was left unlit for 4 months (approximately 3000 hours) at 90% RH. The evaluation results of the Examples and Comparative Examples shown above are summarized in Table 1.

All of Examples 1 to 2 and 4 to 5 had no warping since the time of manufacture, maintained the appearance of the time of manufacture even after being left, and had good light emission conditions. However, the EL light-emitting element of Comparative Example 1.3 has a curved shape toward the light-emitting surface since it was manufactured, and cannot be punched in practical use. However, the light emission was poor.

Furthermore, the EL light-emitting element of Comparative Example 2 had insufficient high-temperature storage stability, warped toward the light-emitting surface, and one out of 10 elements had a light emission failure due to peeling, resulting in low reliability.

In addition, it goes without saying that workability is worse than in the method of the present invention since a warpage prevention film is required separately compared to those shown in Examples 1 to 6.

[Below, margin]

[Brief explanation of the drawing]

1 and 3 are cross-sectional views of the back moisture-proof IJ+h material, and FIG. 2 is a cross-sectional view of the EL light emitting device. Note that the symbols in the figure are as follows. l: Protective layer 2: Back moisture-proof sealing material layer base material 3: Insulating layer 4 Nigellant layer 5: Back electrode 6: Reflective insulating layer 7: Luminescent layer 8: Transparent conductive layer 9: Transparent conductive layer base material 10 Nijirant layer 11: Surface moisture-proof sealing material layer Base material 12: Lead electrode

Claims (1)

[Claims] In a distributed electroluminescent light-emitting device comprising at least a surface moisture-proof sealing material, a transparent surface electrode, a light emitting layer, a back electrode, a lead electrode, and a rear moisture-proof sealing material, the structure of the back moisture-proof sealing material is Contains at least, in order from the outside of the element, a protective layer made of a biaxially stretched polymer film having an average MD and TD heat shrinkage rate of 1% or more when heated to 110°C, a moisture-proof layer made of a metal thin film or metal foil, and a sealant layer. A distributed electroluminescence light emitting device characterized by: