JP2003288029A - Multilayer film for display element and display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer film for a display element having high efficiency for exiting light to the outside and having excellent flexing resistance, and barrier property against water vapor. <P>SOLUTION: The multilayer film for the display element comprises a at least one layer of organic material layer, an inorganic material layer, and a layer of a substance having a lower refractive index than that of the resin substrate layered on a resin substrate. The film is used for the display element. The layers are preferably formed in the order of the organic material layer, the resin substrate, the organic material layer, the inorganic material layer and the layer having a lower refractive index than that of the resin substrate. The layer having the lower refractive index than the resin substrate is formed by, for example, using a porous material having a smaller pore diameter than the wavelength of visible rays as a main component. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film for a display device, which has high efficiency of extracting light to the outside, and is excellent in bending resistance and water vapor barrier property.

[0002]

2. Description of the Related Art In recent years, various display devices have been developed with the progress of information society. Among them, the electroluminescence (EL) element is a self-luminous type and thus has a wide viewing angle and a high response speed, and since it does not require a backlight, a polarizing plate, etc., it can be thin, and is a completely solid-state element. Therefore, it has attracted attention as a thin display device because of its features such as high impact resistance. It is thinner, lighter, and consumes less power than other thin displays. As a general structure of an organic EL light emitting device, a transparent electrode (eg, ITO), a hole injection layer, a light emitting layer made of a low molecule or a polymer, and an electrode (eg, Mg) are provided on a transparent substrate.
Are sequentially stacked, and a protective cover is arranged on the upper layer. In addition, light may be transmitted through and emitted from a transparent substrate (also referred to as a transparent seal) different from the substrate on which the light emitting layer is laminated, such as a top emission type.

For a transparent substrate of an organic EL light emitting device, it is considered to use a light and hard-to-break plastic instead of a heavy and easily-break glass. When transparent plastic is used for the transparent substrate, it can be applied to continuous processing such as roll-to-roll processing, so it is possible to produce more efficiently than when using glass that must be produced by single-wafer processing. . However, when plastic is used as an organic EL element as a transparent substrate, the water vapor barrier property is insufficient,
Since the light emitting material of the organic EL element is easily deteriorated by moisture, it causes a display defect and deteriorates the display quality.

Further, in the structure of the organic EL light emitting device as described above, when a material having a refractive index of about 1.5 to 1.6 is used for the substrate, only about 20% of light can be extracted,
The remaining about 80% was lost as guided light due to total reflection occurring at the interface of the element, and the brightness was insufficient. On the other hand, by increasing the light extraction efficiency in liquid crystal devices, etc., the power consumption of the backlight can be reduced, and the effects of extending the continuous use time and saving energy can be expected. There was a challenge to improve the efficiency of taking out to the.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a laminated film for a display device, which has a high efficiency of extracting light to the outside, and is excellent in bending resistance and water vapor barrier property.

[0006]

According to the law of refraction of classical optics, once emitted light is incident on a layer having a refractive index of 1, a transparent layer having a refractive index much larger than 1 is formed. Even if it passes, it does not generate guided light. Therefore, the entire amount of incident light can be extracted into the air. In a display element such as an organic EL light emitting element, when a layer having a small refractive index is provided between the substrate and the transparent electrode layer, guided light can be reduced and the efficiency of extracting emitted light to the outside can be increased.

That is, the present invention is: (1) A laminated film for a display device, in which at least one organic layer, an inorganic layer and a layer having a smaller refractive index than the resin substrate are laminated on a resin substrate. (2) The laminated film for a display device according to (1), in which each layer is laminated in the order of an organic layer, a resin substrate, an organic layer, an inorganic layer, and a layer having a smaller refractive index than the resin substrate. (3) The laminated film for a display element according to (1) or (2), wherein the layer having a smaller refractive index than the resin substrate has a refractive index of 1.0 to 1.3. (4) The layer whose refractive index is smaller than that of the resin base material is mainly composed of a porous body having a pore diameter smaller than the wavelength of visible light (1)
The laminated film for display devices of (3) to (3). (5) The total thickness is 50 to 1000 μm, and the diameter is 100.
The laminated film for a display device according to any one of (1) to (4), wherein each layer does not crack when bent 180 ° on a mm cylinder. (6) A display device using the laminated film for a display device according to (1) to (5), in which a layer having a refractive index smaller than that of the substrate is arranged so as to be in contact with a transparent electrode layer of the display device. (7) An electroluminescent element, which is formed by using the laminated film for a display element according to any one of (1) to (5) and in which a layer having a refractive index smaller than that of the substrate is arranged in contact with a transparent electrode layer of the electroluminescent element. Is.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The resin base material used in the present invention is not particularly limited as long as it is a transparent resin used for optical applications. For example, acrylic resin, methacrylic resin,
Examples thereof include polycarbonate resin, polyester resin, polyethylene terephthalate resin, polyarylate resin, polyether sulfone resin, alicyclic polyolefin resin, and copolymers thereof.

In order to satisfy the water vapor barrier property required for a substrate for a display device, at least one organic layer or inorganic layer is laminated on the substrate. Examples of the inorganic layer used in the present invention include Si, Al, In, Sn, and Z.
Examples thereof include, but are not limited to, oxides, nitrides, and oxynitrides containing one or more of n, Ti, Cu, Ce and the like.

Examples of the organic material layer used in the present invention include, but are not limited to, acrylic resins, urethane resins, polyester resins and the like.

The arrangement of the resin base material, the inorganic material layer, and the organic material layer is not particularly limited, but in order to improve the adhesion between layers, the water vapor barrier property, and the bending resistance, an organic material layer, a transparent base material, and an organic material layer are provided. The order of the inorganic material layer is preferable. Further, in order to improve the barrier property of the transparent substrate, one or more organic material layers or inorganic material layers may be laminated on the inorganic material layer side. The position of the layer having a smaller refractive index than the resin base material is not particularly limited, but when the laminated film for a display device of the present invention is used for a display device such as an EL device,
The laminated film for a display element is used as a transparent substrate that transmits and emits light, and the layer having a smaller refractive index than the resin base material is provided between the inorganic layer of the transparent substrate and the display element and the transparent electrode layer. preferable. That is, the layer having a smaller refractive index than the resin base material of the laminated film for a display device of the present invention is EL
It is preferably arranged so as to be in contact with the transparent electrode layer of the device. By doing so, light enters the low refractive index layer before being reflected at the interface between the layer such as the water vapor barrier layer and the transparent electrode, so that the emission efficiency can be further improved. Therefore, regarding the configuration of each layer, the order of the organic material layer, the resin base material, the organic material layer, the inorganic material layer, and the layer having a smaller refractive index than the resin base material is most preferable.

The laminated film for a display element of the present invention may be manufactured by any manufacturing method, but considering that it is applied to continuous processing such as roll-to-roll,
The thickness is 50 to 1000 μm and the diameter is 100 m.
It is preferable that each layer does not crack even if it is bent 180 ° on a m-cylinder. If the thickness is less than 50 μm, cracks and wrinkles are likely to occur when bent, and it may not be applicable to continuous processing such as roll-to-roll processing. If the thickness is more than 1000 μm, the weight becomes large, and the advantage of using the resin base material for the transparent substrate for the purpose of weight reduction may be lost. 18 on a 100 mm diameter cylinder
The criteria that each layer does not crack even if it is bent by 0 ° is
It is a standard for handling.

As the layer having a smaller refractive index than the transparent substrate used in the present invention, if it is smaller than the refractive index of the resin substrate,
Although not particularly limited, the refractive index is preferably 1.0 to 1.3, and the value thereof is preferably as close to 1 as the refractive index in vacuum. When the refractive index becomes larger than 1.3,
There is a possibility that the effect of increasing the efficiency of extracting light to the outside cannot be obtained.

The layer having a refractive index smaller than that of the transparent substrate satisfying the above refractive index is preferably a layer containing a porous body as a main component, and the porous body is an organic or inorganic porous body, that is, silica. Examples thereof include aerogel, alumina aerogel, polyimide porous body and the like. The porous body preferably has a pore diameter smaller than the wavelength of visible light, and more preferably has a pore diameter of 0.1 μm or less.

The method for producing the layer whose main component is a porous material having a pore diameter smaller than the wavelength of visible light is not particularly limited. For example, a patterning method using a photomask, a film having a smaller refractive index than the transparent substrate is used. Examples of the method include a method of rubbing with a suitable material such as a file after production, and a method of volatilizing or decomposing one of the two components.

In order to prevent the occurrence of display defects caused by unevenness of the layer having a smaller refractive index than the transparent substrate, a plurality of layers having a smaller refractive index than the resin substrate may be laminated.

[0017]

EXAMPLES Examples of the present invention will be described in detail below, but the present invention is not limited to the following examples. (Example 1) Polyether sulfone resin (refractive index 1.6
5. Epoxy acrylate (Showa High Polymer: VR-60-LAV) 25 wt%, diethylene glycol 50 wt%, ethyl acetate 24 wt%, on a film having a thickness of 200 μm.
A uniform mixed solution containing 1 wt% of a silane coupling agent was applied by a spin coater, dried by heating at 80 ° C. for 10 minutes, and further cured by UV irradiation to form a 2 μm organic material layer. Next, the film on which the organic layer was formed was set in a vacuum tank of a sputtering apparatus, vacuumed to the level of 10 ⁻⁴ Pa, and argon was introduced as a discharge gas at a partial pressure of 0.04 Pa, and oxygen was separated as a reaction gas. A pressure of 0.04 Pa was introduced. When the atmospheric pressure became stable, discharge was started to generate plasma on the Si target, and the sputtering process was performed. When the process became stable, the shutter was opened and the formation of the SiOx inorganic layer on the film was started. When a 50 nm film was deposited, the shutter was closed to complete the film formation. After that, the atmosphere is introduced into the vacuum chamber and S
The film on which the iOx inorganic layer was formed was taken out. Further, on the SiOx inorganic film deposition surface of the film, epoxy acrylate (Showa High Polymer: VR-60-LAV) 25w
t%, diethylene glycol 50 wt%, ethyl acetate 2
A uniform mixed solution of 4 wt% and 1 wt% of silane coupling agent was applied by a spin coater, dried by heating at 80 ° C. for 10 minutes, and further cured by UV irradiation to form a 0.5 μm organic material layer. The film was set in the vacuum tank of the sputtering apparatus again, and the vacuum was evacuated to the level of 10 −4 Pa. Argon was introduced as a discharge gas at a partial pressure of 0.04 Pa and oxygen was introduced as a reaction gas at a partial pressure of 0.04 Pa. When the atmospheric pressure became stable, electric discharge was started to generate plasma on the Si target, and the sputtering process was started. When the process became stable, the shutter was opened and the formation of the SiOx inorganic film on the film was started. When a 50 nm film was deposited, the shutter was closed to complete the film formation. Then, the atmosphere was introduced into the vacuum chamber, and the film having the SiOx inorganic layer formed thereon was taken out.

This film has a smaller refractive index than the resin base material.
Silica airgel film as the first layer (hereinafter, low refractive index layer)
(Refractive index 1.01, hole diameter about 0.05 μm, thickness 2 μm)
Was provided on the SiOx inorganic film side. Low bending of this laminated film
A transparent electrode layer (ITO) and a light emitting layer (TPD / A) on the folding rate layer side.
lq₃) Is provided to produce an organic EL device, and the front brightness, water
Measure the vapor permeability and 180 ° on a 100 mm diameter cylinder
After bending, the bending resistance of the film was visually observed. front
Brightness is 407 cd / m², Water vapor permeability is 0.1g / m²
Less than / day (less than confidence limit), on a 100 mm diameter cylinder
There was no crack even when bent by 180 °. (Example 2) In the same manner as in Example 1, the organic material layer / polyethylene
Ter sulfone resin / organic material layer / inorganic material layer,
As a low refractive index layer on this film, polyimide porous material
(Refractive index 1.20, pore diameter about 0.01 μm, thickness 2 μm)
Was prepared on the SiOx inorganic film side to prepare a laminated film.
On the low refractive index layer side of this laminated film, a transparent electrode layer (IT
O), light emitting layer (TPD / Alq₃) Is provided and the organic EL element is
A child was produced and the same measurement as in Example 1 was performed. Front brightness
Is 359 cd / m2, and water vapor permeability is 0.1 g / m ²/
less than day (less than confidence limit), on a 100 mm diameter cylinder
There was no crack when bent 180 °. (Example 3) Polycarbonate resin was used as the resin base material of the transparent substrate.
Oil (refractive index 1.58, thickness 200 μm), low refractive index layer
Silica airgel (refractive index 1.01, pore size about 0.05μ
m, thickness 2 μm) as in Example 1.
A child was created and measurements were taken. Front brightness is 397 cd / m
², Water vapor permeability is 0.1g / m²Less than / day (confidence limit
(Below the boundary), bend 180 ° on a 100 mm diameter cylinder
There was no crack.

[0019]

[Table 1]

(Comparative Example 1) In Example 1, an organic EL device having no low refractive index layer was prepared, and the same measurement as in Example 1 was performed. The front luminance was 251 cd / m ² , the water vapor permeability was less than 0.1 g / m ² / day (less than the confidence limit), and there was no crack even when bent 180 ° on a cylinder having a diameter of 100 mm. (Comparative Example 2) The base material of the transparent substrate was glass (refractive index 1.5
2, thickness 700 μm), and silica airgel (refractive index 1.01, pore size about 0.05 μm, thickness 2 μm) was provided on the glass as a low refractive index layer to prepare a transparent substrate. The transparent substrate is provided with an electrode and a light emitting layer on the low refractive index layer side,
An L element was produced and the same measurement as in Example 1 was performed. Front brightness is 414 cd / m 2, water vapor permeability is 0.1 g / m
Less than 2 / day (less than confidence limit), but diameter 10
Since it was impossible to bend 180 ° on a 0 mm cylinder, measurement could not be performed.

[0021]

[Table 2]

[0022]

EFFECT OF THE INVENTION Since the laminated film for a display element of the present invention has a high efficiency of extracting light to the outside, and has excellent bending resistance and water vapor barrier property, the film of the present invention can be produced by organic E
When applied to the L light emitting element, it is possible to obtain a display device that is light and hard to break and has higher reliability.

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Claims (7)

[Claims] 1. A laminated film for a display device, comprising: a resin substrate, and at least one organic layer, an inorganic layer, and a layer having a refractive index smaller than that of the resin layer laminated on the resin substrate. 2. The laminated film for a display element according to claim 1, wherein the respective layers are laminated in the order of an organic material layer, a resin base material, an organic material layer, an inorganic material layer, and a layer having a smaller refractive index than the resin base material. 3. The laminated film for a display element according to claim 1, wherein the layer having a smaller refractive index than the resin substrate has a refractive index of 1.0 to 1.3. 4. The laminated film for a display device according to claim 1, wherein the layer having a refractive index smaller than that of the resin base material is mainly composed of a porous body having a pore diameter smaller than a wavelength of visible light. . 5. The laminated film for a display element according to claim 1, which has a total thickness of 50 to 1000 μm and does not crack even when bent 180 ° on a cylinder having a diameter of 100 mm. 6. A display comprising the laminated film for a display element according to claim 1, wherein a layer having a refractive index smaller than that of the resin substrate is in contact with a transparent electrode layer of the display element. element. 7. The laminated film for a display device according to claim 1, wherein a layer having a refractive index smaller than that of the resin substrate is arranged so as to be in contact with the transparent electrode layer of the electroluminescence device. Electroluminescent device.