JP2001155854A - Organic el element sealing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide EL element sealing method that can prevent bad sealing by suppressing pressure rising of sealed space in adhering. SOLUTION: The EL element sealing method of the present invention comprises steps of coating adhesive 2 to a sealing member 1 having a recess 12 to form a sealing line, overlapping the sealing member 1 and a transparent substrate 3, and press-attaching both members. The adhesive 2 is formed with a sump 21 at a position corresponding to the recess 12, and a tunnel T is formed at the sump to communicate inside and outside spaces of a sealing line, therefore, the pressure rising according to volume reducing of a sealing space K is prevented. The tunnel T is pressed toward both members and closed by the adhesive 2 when the pressing step is carried out. A hole may be formed at a position of the sealing member where the adhesive is coated instead of recess 12, and the tunnel is formed at the hole. If both members are reversed after pressing step, the tunnel is closed as the adhesive in the hole flows toward the transparent substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for sealing an organic electroluminescence (EL) element.

[0002]

2. Description of the Related Art In order to improve the reliability and extend the life of an organic EL device, the light emitting layers and electrodes constituting the organic EL laminated film must be surely made of moisture or oxygen (hereinafter also referred to as "moisture").
It is important to block from For this purpose, organic E
A technique is known in which a transparent substrate on which an L laminated film is formed and a sealing member are integrated via an adhesive to protect the organic EL laminated film sealed therebetween from moisture and the like. . For example, an adhesive is applied to the outer peripheral portion of the sealing member, a transparent substrate is superimposed, and the organic EL laminated film is sealed in a space surrounded by the two and the adhesive (hereinafter, also referred to as a “sealing space”). Then, the adhesive sandwiched between the sealing member and the transparent substrate is compressed by pressing the sealing member and the transparent substrate, and then the adhesive is cured.

[0003]

However, when a transparent substrate is overlaid on the sealing member and pressed, the volume of the sealing space decreases as the adhesive is crushed, and the pressure in the sealing space is reduced accordingly. To rise. Due to the influence of the internal pressure, the degree of spreading of the adhesive 2 becomes uneven as shown in FIG. 10 and the shape of the sealing line joining the sealing member and the transparent substrate 3 is disturbed, There is a problem in that the gas in the air escapes by forming a hole (airway) in the adhesive, and the airway remains until after the adhesive is hardened, resulting in poor sealing of the element.

In order to prevent this sealing failure, Japanese Patent Laid-Open No.
Japanese Patent Application Publication No. 176571 discloses a method for manufacturing an organic EL device in which pressure bonding between a sealing member and a transparent substrate is performed under reduced pressure. However, even with this manufacturing method, it is difficult to sufficiently prevent the shape of the sealing line from being disordered, and it is troublesome to adjust the atmospheric pressure.

An object of the present invention is to provide a method for sealing an organic EL element, which prevents the occurrence of defective sealing by reducing a pressure rise in a sealing space at the time of bonding.

[0006]

The present inventors have found that the above-mentioned problems can be solved by providing a groove or a hole in one of the sealing member and the transparent substrate, and have completed the present invention.

The method of sealing an organic EL element according to the first invention is a method of sealing an organic EL element in which a transparent substrate on which an organic EL laminated film is formed and a sealing member are integrated with an adhesive. An application step of applying an adhesive to one of the transparent substrate and the sealing member to form a sealing line, and an arrangement in which the one member to which the adhesive is applied is overlapped with the other member And a crimping step of crimping the one member and the other member. At least one of the one member and the other member communicates the inner and outer spaces of the sealing line in the disposing step. A groove for forming a tunnel to be formed is provided, and the communication between the inner and outer spaces is blocked by the adhesive in the pressing step.

In a third aspect of the present invention, there is provided a method for sealing an organic EL element, comprising: applying an adhesive to one of the transparent substrate and the sealing member to form a sealing line; An arranging step of laminating the one member to which the adhesive is applied with the other member, a crimping step of crimping the one member and the other member, and the crimped one member and the other member A reversing step of inverting the member and upside down, a part of the adhesive forming the sealing line is applied in a hole provided in the one member, and in the disposing step, A gap is formed to communicate the inner and outer spaces of the sealing line, and the adhesive applied in the holes flows down in the reversing step, thereby interrupting the communication of the inner and outer spaces.

As the above-mentioned "transparent substrate", a plate-like material, a sheet-like material, a film-like material or the like made of a transparent material such as glass, resin and quartz can be used. this house,
It is particularly preferable to use a glass plate having excellent barrier properties against moisture and the like. An “organic EL laminated film” is formed by laminating an anode, an organic EL film, and a cathode on this transparent substrate. Organic E
The L film may be composed of only a light emitting layer, may have a hole transport layer and / or an electron transport layer in addition to the light emitting layer, and further has a hole injection layer and / or an electron injection layer. Is also good. Various known materials can be used for the materials constituting the anode, the cathode, and the organic EL film. A method for forming each of these layers may be appropriately selected from methods such as a vacuum evaporation method, a spin coating method, a casting method, a sputtering method, and an LB method.

The "sealing member" includes stainless steel,
Metals such as aluminum or an alloy thereof, glasses such as soda-lime glass and silicate glass, and resins composed of one or more of resins such as acrylic resins and styrene resins can be used. Among them, those made of metals or glasses are preferred. The shape of the sealing member is not particularly limited, and may be, for example, a plate shape, a cap shape, or the like.

As the "adhesive" used in the sealing method of the present invention, an epoxy resin-based adhesive, an acrylate-based adhesive, a thermosetting resin, a photocurable resin, or the like can be used. Among them, those that form a cured product having low permeability to moisture and the like are preferable. In addition, an adhesive made of a photo-curable resin is preferably used because it can reduce thermal stress on the element and is excellent in rapid curability. In particular, it is preferable to use a cationically polymerizable ultraviolet-curable epoxy resin-based adhesive.

The viscosity of the adhesive before curing is usually about 50 to 20,000 Pa · s at room temperature.
Among the sealing methods of the present invention, the method of the first invention uses an adhesive having a relatively high viscosity (for example, 3,000 to 20,000 Pa · s, more preferably 5,000 to 10,000 Pa · s). It is preferably applied in cases. Further, the method of the third invention has a relatively low viscosity (for example, 50 to 3,000P).
a · s, more preferably 100 to 500 Pa · s) It is preferably applied when an adhesive is used. The application amount of the adhesive to the application length is usually 0.2 to 200 mg / cm.
(Preferably 1.5 to 120 mg / cm), the application width of the adhesive before press bonding is usually 0.2 to 5 mm (preferably 0.5 to 3 mm), and the height (application thickness) is usually 0.1.
It is 1 to 3 mm (preferably 0.2 to 2 mm). The upper end of the adhesive at the center in the width direction of the groove is preferably lower than the upper end of the groove, but even when the upper end of the adhesive is higher than the upper end of the groove, If the adhesive is depressed, it is possible to form a tunnel in the initial stage of the pressure bonding step, and the effect of the present invention can be obtained.

The adhesive is applied to at least one of the sealing member and the transparent substrate using a dispenser or the like.
Normally, it is preferable to apply an adhesive to the sealing member which is easier to handle than the transparent substrate on which the organic EL laminated film is formed. In the sealing method of the first invention, the member having the groove and the member to which the adhesive is applied are not necessarily the same, but are preferably the same member. Also,
In the sealing method of the third invention, the member having the hole and the member to which the adhesive is applied are the same. The member (one member) to which this adhesive is applied is, as in the second and fourth inventions,
Preferably, it is a sealing member.

A groove or a hole is formed in one of the transparent substrate and the sealing member. here,
The “groove” refers to a concave portion having an opening at a position other than the upper end, and the “hole” refers to a concave portion having no opening at a position other than the upper end. Usually, it is preferable to form a groove or a hole on the side of the sealing member. When the sealing member is made of a metal, it is easier to form the groove or the hole than a transparent substrate usually made of glass or the like. Therefore, it is more preferable. A metal press or the like can be used as a method for forming the grooves or holes. When forming a groove or a hole in a sealing member made of glass or the like or a transparent substrate, a method such as cutting may be used. Hereinafter, a case where a groove or a hole is formed on the sealing member side will be described as an example.

The above-mentioned "groove" is usually formed so as to intersect (preferably orthogonally) with the sealing line in the above-mentioned arrangement step. When the sealing member 1 has a flat plate shape as shown in FIG. 2A, a groove 12 having an open end is provided from a predetermined position of the sealing member to an outer peripheral end of the sealing member. preferable. Further, when the side wall 14 is formed on the outer peripheral portion of the sealing member 1 as shown in FIG.
In the case where the flange 11 is formed on the outer periphery of the sealing member 1 as shown in (c), a double-ended groove 12 is provided so as to penetrate the side wall 14 or the flange 11 in the width direction. Is preferred. 2A and 2B are examples of shapes suitable for a case where the sealing member is made of glass, and FIG. 2C is an example of a shape suitable for a case where the sealing member is made of metal.

When an adhesive is applied to the outer peripheral portion of the sealing member to form a sealing line, the amount of the adhesive applied to each portion of the sealing line is generally substantially constant. At the crossing point, the adhesive has depressions. When a transparent substrate is superimposed on the sealing member, a tunnel is formed between the recess of the adhesive and the transparent substrate, the tunnel communicating with the inner and outer spaces of the sealing line. At the beginning of the compression bonding step, the gas in the sealed space escapes through the tunnel as the volume of the sealed space decreases, thereby preventing the pressure in the sealed space from rising. As crimping progresses, the tunnel gradually shrinks due to the adhesive crushed between the sealing member and the transparent substrate,
Eventually disappears (the tunnel is closed). Thereby, communication between the inside and outside of the sealed space is cut off.

The cross-sectional shape of the groove may be any of a U-shape, a U-shape, a V-shape, and the like, but is preferably a U-shape because the adhesive is easily filled in every corner in the pressure bonding step. The size of the groove is appropriately set according to the viscosity and application amount of the adhesive to be used, the width of the sealing line after the adhesive is cured, and the like. Normally, the upper end has a width of 3 to 10 mm and a length of 2 to 10 m
m, depth 0.5 to 3 mm (more preferably 3 to 5 m in width)
m, a length of 3 to 5 mm, and a depth of 0.5 to 2 mm). If the groove is too small, the tunnel will be closed before the volume of the sealed space becomes sufficiently small. On the other hand, when the groove is too large, the obtained organic EL element tends to have a low barrier property against moisture and the like.

As shown in FIGS. 3 (a) and 3 (b), the "hole" is formed at a part of the sealing member 1 where the adhesive 2 is to be applied, preferably at the position where the adhesive 2 is applied. It is preferably formed as a rectangular hole 13 having a long side in the direction. FIG. 3A shows an example of a shape suitable for a case where the sealing member is made of glass, and FIG. 3B shows an example of a shape suitable for a case where the sealing member is made of metal.

In the above-mentioned application step, a part of the adhesive constituting the sealing line enters the hole and is applied.
Therefore, when the transparent substrate is overlaid on the sealing member, a tunnel is formed between the sealing member at the position where the hole is formed and the transparent substrate and communicates with the inner and outer spaces of the sealing line. In the pressure bonding step, the gas in the sealed space escapes through the tunnel as the volume of the sealed space decreases, thereby preventing the pressure in the sealed space from rising. After the crimping process,
When the sealing member and the transparent substrate are turned upside down, the adhesive applied in the hole flows down to the transparent substrate side to close the gap. Thereby, communication between the inside and outside of the sealed space is cut off.

Although the shape of the hole is not particularly limited, a preferred shape in a section perpendicular to the sealing line is a U-shape or a U-shape, and a preferred shape in a section parallel to the sealing line and perpendicular to the sealing member. May be U-shaped, arc-shaped, U-shaped, or the like. The size of the hole is appropriately set according to the viscosity and application amount of the adhesive to be used, the width of the sealing line after the adhesive is cured, and the like. Usually, the width of the opening to the surface of the sealing member is 1 to 6 mm, the length is 3 to 10 mm, the depth is 0.5 to 3 mm, (more preferably the width is 2 to 3 mm).
(4 mm, length 4 to 8 mm, depth 0.5 to 2 mm). If the width of the hole is too small, the adhesive may protrude from the hole in the width direction of the sealing line, making it impossible to form a tunnel in the pressure bonding process. If the length or depth of the hole is too small, the tunnel may be closed before the volume of the sealed space becomes sufficiently small.
On the other hand, when the hole is too large, it takes a long time to cut off the communication by flowing down the adhesive in the reversing step, and the obtained organic EL element tends to have low barrier properties against moisture and the like. .

The width and thickness of the adhesive layer after completion of the pressure bonding step or the reversing step are substantially equal to the width and thickness of the sealing line after the adhesive is cured, and the width is 1 to 5 mm.
(More preferably 2-4 mm), thickness 1-200 μm
(More preferably 5 to 100 μm). Then, the adhesive may be cured by means such as ultraviolet irradiation, and the sealing member and the transparent substrate may be integrally bonded.
In addition, the said groove | channel and a hole may be provided in one place of a sealing line, and may be provided in two or more places. Usually, since it is easy to mold and it is easy to obtain an organic EL element having a high barrier property against moisture and the like, it is preferable to provide the organic EL element at one place.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically by way of examples. (Example 1) As shown in FIG. 4, the sealing member 1 is formed by a metal press, is made of a stainless steel plate having a thickness of 0.5 mm, and has a square cap shape of 30 mm long × 50 mm wide × 10 mm high. The outer peripheral portion has a flange portion 3 having a width of 3 mm. The flange 11 located on one short side of the sealing member 1 has a double-ended groove 12 that penetrates the flange 11 in the width direction substantially at the center in the length direction. The cross-sectional shape of the groove 12 is U-shaped, the width at the upper end is 3 mm,
The depth is 0.8 mm. 1.5 mm inward from the outer peripheral end of the flange portion 11, a cationically polymerizable ultraviolet-curable epoxy resin-based adhesive (trade name “XNR” manufactured by Ciba-Geigy)
5493T ") 2 was applied with a dispenser to form an annular sealing line. The viscosity of this adhesive is 5,50
At 0 Pa · s / 25 ° C., the applied amount of the adhesive with respect to the dispenser movement amount was 20 mg / cm, and the applied adhesive 2 had a substantially semicircular cross section of 0.8 mm in width and 0.5 mm in height. At this time, at the position where the groove 12 is formed, the adhesive 2
A depression 21 was formed in the substrate.

Next, as shown in FIG.
The transparent substrate 3 on which the L laminated film is formed is overlaid on the sealing member 1, and the sealing member 1, the transparent substrate 3 and the adhesive 2 (the sealing line) seal the organic EL laminated film. K
Was partitioned. At this time, a tunnel T communicating with the sealing space K and the external space is formed between the depression 21 and the transparent substrate 3. When the sealing member 1 and the transparent substrate 3 are pressed against each other in this state, the adhesive 2 is gradually crushed, the volume of the sealing space K is reduced, and the gas in the sealing space K is pushed out to the external space through the tunnel T. It is. This prevents the pressure in the sealed space K from rising. As the pressing proceeds, the tunnel T is gradually compressed by the crushed adhesive 2, and finally the tunnel T disappears as shown in FIG. 1B, and the sealing space K and the external space are shut off. . afterwards,
The adhesive 2 was cured by irradiating ultraviolet rays. The width of the adhesive 2 after curing was 2.5 mm, and the thickness was 100 μm.

In the first embodiment, the member provided with the groove and the member to which the adhesive is applied are the same.
As shown in (1), a groove 31 may be provided on the transparent substrate side 3, and the adhesive 2 may be applied to the sealing member side 1. In this case, a tunnel T is formed between the adhesive 2 and the groove 31, and as the pressing proceeds, the crushed adhesive 2 is filled in the groove 31 to close the tunnel T.

(Embodiment 2) As shown in FIG.
A sealing member 1 made of a glass plate having a size of mx 50 mm wide x 1.1 mm thick is used, and a portion 5 mm inside, 2 mm wide and 2 mm deep in parallel with this short side is placed at a position 2 mm inside from one short side. A hole 13 having a thickness of 0.8 mm was formed by a cutting method. The cross-sectional shape of the hole 13 is a U-shape in both a cross section perpendicular to the sealing line and a cross section parallel to the sealing line and perpendicular to the sealing member. The same adhesive as that used in Example 1 was applied on the inner side of 2 mm from the outer peripheral end of the sealing member 1 under the same conditions to form an annular sealing line. This sealing line extends through the hole 13, and the adhesive 2 at this point is applied in the hole 13.

The application width of the adhesive 2 is smaller than the width of the hole 13, and the upper end of the in-hole adhesive 22 applied in the hole 13 is lower than the upper end of the hole 13 as shown in FIG. Has become. Therefore, when the transparent substrate 3 is overlaid on the sealing member 1, a tunnel T communicating with the sealing space K and the external space is formed between the sealing member 1 located on the hole 13 and the transparent substrate 3. Is done. When the sealing member 1 and the transparent substrate 3 are pressed against each other in this state, the adhesive 2 is gradually crushed to reduce the volume of the sealing space K, and the gas in the sealing space K is pushed out to the external space through the tunnel T. It is.
This prevents the pressure in the sealed space K from rising. FIG.
As shown in (b), unlike the first embodiment, the tunnel T is maintained until the end of the crimping. Next, when the sealing member 1 and the transparent substrate 2 are turned upside down, the adhesive 22 in the hole flows down and adheres to the transparent substrate 3 as shown in FIG. 7C, and partially as shown in FIG. Is spread on both sides of the hole 13 by capillary action. Thereby, the tunnel T is closed, and the sealed space K and the external space are shut off. Thereafter, the adhesive 2 was cured by irradiating ultraviolet rays. The width of the adhesive 2 after curing was 2.5 mm, and the thickness was 100 μm.

When the organic EL devices obtained in Examples 1 and 2 were visually evaluated, as shown in FIG. 9, the shape of the adhesive 2 forming the sealing line was disturbed. There was no airway at all that allowed the space inside and outside the adhesive to communicate. Further, the width of the sealing line was almost the same at any position in the circumferential direction of the organic EL element. FIG. 9 is a schematic plan view showing the obtained organic EL element as viewed from the transparent substrate side. Reference numeral 3 denotes a transparent substrate, and reference numeral 4 denotes an organic EL laminated film.

[0028]

According to the sealing method of the present invention, a groove or a hole is provided in the sealing member or the transparent substrate, and the groove or the hole is used to pressurize the sealing member and the transparent substrate when the sealing member is pressed. A communication hole (tunnel) for allowing gas to escape to the outside is formed. This tunnel prevents a pressure increase due to a decrease in the sealing space at the time of crimping. As the press-bonding progresses or in a reversing step after the press-bonding, the communication holes are closed by the adhesive, and the inner and outer spaces of the sealing line are shut off.

Note that, unlike the present invention in which a groove or a hole is provided, for example, when the adhesive is applied, the supply of the adhesive from the dispenser is temporarily stopped in the middle to apply the adhesive to a part of the sealing line. When the transparent substrate and the sealing member are overlapped with each other, a tunnel is formed by the discontinuity. However, according to this method, it is difficult to control the spread of the adhesive at the time of crimping, so that the tunnel cannot be reliably closed at or after crimping, and sealing failure frequently occurs. According to the method of the present invention, by a simple method of providing a groove or a hole in the sealing member or the transparent substrate, it is possible to easily control the formation of the tunnel for communicating the inner and outer spaces and the timing of the blocking, and furthermore, to ensure the blocking. It can be carried out.

[Brief description of the drawings]

FIGS. 1A and 1B show a sealing method of Example 1 viewed from a cross section taken along line II of FIG. 4, wherein FIG. 1A shows an arrangement step and FIG.

FIGS. 2A to 2C are perspective views illustrating the shape of a groove provided in a sealing member in the present invention.

FIGS. 3A and 3B are perspective views illustrating the shape of a hole provided in a sealing member in the present invention.

FIG. 4 is a perspective view illustrating a sealing member used in the sealing method according to the first embodiment.

FIG. 5 is a cross-sectional view illustrating an arrangement step in another example of the sealing method according to the first embodiment.

FIG. 6 is a perspective view illustrating a sealing member used in a sealing method according to a second embodiment.

7A and 7B show a sealing method according to the second embodiment viewed from a cross section taken along the line VII-VII in FIG. 6, wherein FIG. 7A shows an arrangement step, FIG. Is shown.

8 is a sectional view taken along line VIII-VIII in FIG.

FIG. 9 is a schematic plan view showing a sealing line of an organic EL element obtained in an example.

FIG. 10 is a schematic plan view showing a sealing line of an organic EL element obtained in a comparative example.

[Explanation of symbols]

1; sealing member, 11; flange, 12; groove, 13; hole, 2;
Adhesive, 21; dent, 22; adhesive in hole, 3: transparent substrate, 4: organic EL laminated film

Claims (4)

[Claims] 1. A method for sealing an organic EL element in which a transparent substrate on which an organic EL laminated film is formed and a sealing member are integrated by an adhesive, wherein the transparent substrate and any of the sealing members are provided. A coating step of forming a sealing line by applying an adhesive to one of the members, an arranging step of superimposing the one member to which the adhesive has been applied on the other member, and the one member and the other of the other members A crimping step of crimping the member and at least one of the one member and the other member is provided with a groove for forming a tunnel communicating the inner and outer spaces of the sealing line in the disposing step. Wherein the communication between the inner and outer spaces is interrupted by the adhesive in the pressing step. 2. The one member is the sealing member,
The method according to claim 1, wherein the groove is provided in the sealing member. 3. A method for sealing an organic EL element in which a transparent substrate on which an organic EL laminated film is formed and a sealing member are integrated by an adhesive, wherein the transparent substrate and one of the sealing members are provided. An application step of applying an adhesive to one member to form a sealing line, an arranging step of overlapping the one member coated with the adhesive with the other member, and the one member and the other And a reversing step of reversing the crimped one member and the other member up and down, and a part of the adhesive forming the sealing line is the one member Is formed in the hole provided in the hole, and a gap is formed on the hole in the arrangement step to communicate the inner and outer spaces of the sealing line, and the adhesive applied in the hole flows down in the inversion step. By doing the above Method of sealing the organic EL element characterized in that the communication of the outer space is blocked. 4. The method according to claim 3, wherein the one member is the sealing member.