JP2987177B2 - Transparent conductive moisture-proof film and EL light emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a transparent conductive material used in a wide range of applications such as packaging materials for foods and medicines, and protective materials for EL (Electroluminescence) light emitting devices. It relates to a moisture permeable film.

[Conventional technology]

Use of a transparent and moisture-permeable film material to prevent deterioration of the contents of food and medicine packaging, or to protect EL light-emitting elements and prevent malfunction of membrane switches (touch panels) in the electronics industry. Is desired.

Conventionally known film materials of this type use various plastics such as polyethylene terephthalate and vinyl chloride as a film base material, but in many cases, lack moisture resistance. For this reason, as shown in JP-B-53-12953 and JP-A-60-27532, a thin film of a silicon compound or magnesium oxide is formed on a base film to form the above-described moisture-permeable film. There are some ideas for improvement.

[Problems to be solved by the invention]

However, the above-mentioned known film materials cannot be said to have sufficient moisture resistance yet, and require a high degree of moisture resistance.
There was a drawback that it was difficult to apply it to protective materials for EL light-emitting devices.

In addition, any of the above-mentioned known film materials is easily charged when used, and foreign matter or dust is attracted or mixed in by the charging, resulting in poor sealing or poor appearance, or malfunction as a protective material for EL light emitting elements. There was a problem that caused.

The present invention has been made in view of the above-mentioned conventional problems, and firstly, provides a moisture-permeable film material which is excellent in moisture-permeable property and does not cause poor sealing, poor appearance or malfunction due to charging. The purpose is. Second, it is another object of the present invention to provide an EL light emitting device in which an EL light emitting element is covered and sealed with the above film material.

[Means for solving the problem]

The present inventors have conducted intensive studies to achieve the above object, and as a result, a first layer composed of a transparent conductive layer on a transparent film substrate and a transparent layer composed of a specific metal oxide thereon. According to the transparent conductive moisture-permeable film provided with two layers, the moisture-permeable property can be greatly improved, and since the film itself has conductivity, it is possible to avoid the adsorption and mixing of foreign matter and dust caused by charging. As a result, the present inventors have found that it is possible to prevent poor sealing, poor appearance, malfunction, and the like, and have completed the present invention.

That is, a first aspect of the present invention is that a first layer made of a transparent conductive layer is provided on a transparent film substrate, and an oxide of at least one metal selected from Ta, Al, and Zr is further provided thereon. The present invention relates to a transparent conductive moisture-permeable film provided with a transparent second layer made of:

A second aspect of the present invention relates to an EL light-emitting device in which a BL light-emitting element is covered and sealed by the transparent conductive moisture-permeable film according to the first invention.

[Structure and operation of the invention]

The transparent film substrate used in the present invention has a thickness of 5 to 300 μm with flexibility and transparency.
Plastic films, for example, films of various plastics such as polyethylene terephthalate, polyimide, polyether sulfone, polyether ketone, polycarbonate, polypropylene, polyamide, polyacryl, cellulose propionate, polyvinyl chloride, polystyrene, polyvinyl butyral, and cellophane Is mentioned.

This film substrate is subjected to an etching treatment or undercoat treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, etc. on its surface in advance,
You may make it improve the adhesiveness with respect to the said base material of the conductive layer provided on this. Before providing the conductive layer, dust removal and cleaning may be performed by solvent cleaning or ultrasonic cleaning as necessary.

As the transparent conductive layer provided as the first layer on the film base material, there are usually indium oxide, tin oxide, a mixture of indium oxide and tin oxide (hereinafter referred to as ITO), a mixture of tin oxide and antimony oxide, and the like. Although metal oxides are used, ITO is most preferred in terms of conductivity and transparency. These conductive layers may be formed by using a known thin film forming technique such as a vacuum deposition method, a sputtering method, and an ion plating method.

The thickness of the transparent conductive layer is preferably 50 mm or more, and if it is thinner, it becomes an island-like film, and it is difficult to form a continuous film having good conductivity with a surface resistance of 10 ³ Ω / □ or less, The effect of improving moisture permeability cannot be expected. on the other hand,
If the thickness is too large, the transparency and the moisture resistance due to cracks are reduced. Therefore, a particularly preferable thickness is preferably about 100 to 4,000 mm.

The transparent second layer provided on the first layer made of such a conductive layer is made of an oxide of at least one metal selected from Ta, Al, and Zr.
a ₂ , O ₃ , Al ₂ O ₃ , ZrO ₂ or a mixture thereof is used. Such a metal oxide layer gives a good result in improving moisture permeation resistance and transparency by being laminated on the above-mentioned conductive layer, and has a close contact with an adhesive layer described later provided thereon. It also gives good results for sex.

This metal oxide layer can be formed in the same manner as in the case of the conductive layer. For example, using a metal Ta, Al or Zr as a deposition material, depositing them in an oxygen atmosphere, or using an oxide of each of the above metals as a deposition material and forming them in a vacuum. it can.

The thickness of such a metal oxide layer is usually between 20 and 4,000
Å, preferably in the range of 50 to 2,000Å. If this layer is too thin, it becomes a film having an island structure, and the adhesion to the adhesive layer described later is not improved, and the moisture permeability is not improved. On the other hand, if the thickness is too large, coloring and cracks are liable to occur, in which case the transparency and the moisture resistance are reduced.

In the transparent conductive moisture-permeable film according to the present invention, an adhesive layer is usually further formed on the second layer made of the above-mentioned metal oxide when used. As this adhesive layer, a transparent pressure-sensitive adhesive or a transparent heat-sensitive adhesive is used, and these adhesives are provided only on one portion such as a peripheral portion on the second layer made of metal oxide. Or may be provided on the entire surface.

The pressure-sensitive adhesive can be used without any particular limitation as long as it has transparency, and among them, acrylic adhesive, silicone adhesive, rubber adhesive and the like are preferably used. The elastic modulus of these pressure-sensitive adhesives is 1 × 10 ⁵
~ 1 × 10 ⁷ dyne / cm ² , thickness 2μm or more, usually 5
Desirably, it is in the range of 500500 μm. If the elastic modulus is too small, it may protrude to the side surface after bonding, and if it is too large, the bonding workability and the sealing property are easily impaired. Further, if the thickness is too small, the sealing property is deteriorated. On the other hand, if the thickness is too large, the transparency is lowered, and good results are hardly obtained in terms of bonding workability and cost.

Examples of the heat-sensitive adhesive include, for example, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-based ionomer resin, and the like, provided that they do not impair transparency or moisture resistance. Can be used without limitation. These adhesives may be provided by a method of dry laminating a film prepared in advance, or may be provided by an extrusion lamination method in which a film is melt-extruded. Its thickness is 2 μm as in the case of the pressure-sensitive adhesive.
As described above, it is generally desirable that the thickness be in the range of 5 to 500 μm.

FIG. 1 shows an example of the transparent conductive moisture-permeable film having the above structure, wherein 1 is a transparent film substrate, 2 is a transparent conductive layer (first layer), and 3 is a transparent metal oxide. The material layer (second layer) and 4 are transparent adhesive layers.

In the present invention, a transparent conductive moisture-permeable film having an adhesive layer as shown in FIG. 1 is used, or an adhesive is separately applied, and the EL film is formed on the film.
By covering and sealing the light emitting element, it is possible to obtain an EL light emitting device which is excellent in transparency and moisture permeation resistance and in which no defective sealing due to charging is observed.

〔The invention's effect〕

As described above, according to the present invention, it is possible to provide a transparent conductive moisture-permeable film having excellent moisture permeability and transparency, and having no risk of causing poor sealing, poor appearance or malfunction due to charging. it can.

Also, since this film has good conductivity,
It can also be applied as an electromagnetic wave shielding material or the like, which has been difficult to apply with conventional moisture-permeable films. Further, this film has excellent durability in a high-temperature and high-humidity atmosphere, and also has practically desirable characteristics in this regard.

In an EL light emitting device formed using a film having improved moisture permeability and transparency as described above, the coated film has the above-described characteristics, so that the coated film has good light emitting performance, and has a light emission caused by charging. It has the feature that there is no performance degradation or malfunction.

〔Example〕

Next, an embodiment of the present invention will be described in more detail.

Example 1 The surface of a transparent polyethylene terephthalate film (hereinafter referred to as PET film) having a thickness of 50 μm was discharged in a 4 × 10 ⁻³ Torr atmosphere composed of 80% argon gas and 20% oxygen gas. High frequency sputter etching treatment was performed at 3 W · sec / cm ² .

Then, on the treated surface, indium-tin (weight ratio 9: 9) in the same atmosphere gas without breaking the vacuum degree.
1) A transparent conductive layer made of ITO with a thickness of about 1,000 mm was formed by a reactive sputtering method using an alloy. The surface resistance of this film was 100Ω / □.

Next, the above-mentioned transparent conductive layer was used as a first layer, and Ta ₂ O ₅ was further vacuum-deposited on this layer by an electron beam heating method at a degree of vacuum of 2 to 4 × 10 ⁻⁴ Torr to form a layer. About
A transparent metal oxide layer of 150 ° Ta ₂ O ₅ was formed as a second layer. The surface resistance of this film was 110Ω / □.

Then, on the second layer made of the metal oxide, as a pressure-sensitive adhesive layer, an acrylic transparent pressure-sensitive adhesive (n-acrylic acid) having an elastic modulus adjusted to 1 × 10 ⁶ dyne / cm ^2.
100 parts by weight of an acrylic copolymer having a weight ratio of butyl, acrylic acid and vinyl acetate of 100: 2: 5 and 1 part by weight of an isocyanate-based crosslinking agent) is formed to a thickness of about 25 μm, A transparent conductive moisture-permeable film having the structure shown in FIG. 1 was produced.

Example 2 A transparent conductive moisture-permeable film was produced in the same manner as in Example 1 except that a polyethylene-based heat-sensitive adhesive layer having a thickness of 50 μm was formed instead of the pressure-sensitive adhesive layer. did.

Examples 3 and 4 Except that a 25 μm-thick transparent polyethersulfone film (Example 3) and a 80 μm-thick transparent polycarbonate film (Example 4) were used as film substrates, respectively. In the same manner as in Example 2, two kinds of transparent conductive moisture-proof films were produced.

Examples 5 and 6 A second layer made of a transparent metal oxide was applied to a thickness of about 150 mm.
Al ₂ O ₃ (Example 5), except that so as to constitute respective thickness of approximately 150Å of ZrO ₂ (Example 6), the same procedure as in Example 2, two transparent conductive impermeability A wet film was prepared.

Comparative Example 1 A transparent moisture-permeable film was produced in the same manner as in Example 2, except that both the first layer made of the transparent conductive layer and the second layer made of the transparent metal oxide layer were not formed.

Comparative Example 2 A transparent conductive moisture-permeable film was produced in the same manner as in Example 2, except that the second layer made of a transparent metal oxide layer was not formed.

Comparative Examples 3 and 4 Example 1 except that both the first layer made of a transparent conductive layer and the second layer made of a transparent metal oxide layer were not formed.
In the same manner as in 3 and 4, two kinds of transparent moisture-proof films were produced.

The following characteristic tests were performed on the moisture-permeable films of the above Examples and Comparative Examples. The results were as shown in Table 1 below.

<Visible light transmittance> The light transmittance at a wavelength of 550 nm was measured using a spectrophotometer UV-240 manufactured by Shimadzu Corporation.

<Moisture Permeability> As shown in FIG. 2, silica gel is sealed in a bag shape using two moisture permeable films cut into a size of about 170 mm × 170 mm. The seal is located approximately from the edges of the two films.
The parts in the 5 mm area were overlapped, and pressure- or heat-sensitive bonding was performed using an adhesive layer. After this sealing, 60 ℃, 9
The sample was left in an atmosphere of 5% RH for several tens of hours, and the change in mass was measured. The change in mass per unit time and unit area was determined, and this was defined as the moisture permeability (mmg / m ² · hour).

In FIG. 2, 1 is a transparent film substrate, 2 is a first layer of a transparent conductive layer, 3 is a second layer of a transparent metal oxide layer, 4 is a transparent adhesive layer, Is encapsulated silica gel.

<Durability> The properties and appearance of the moisture-permeable film when left for 500 hours in an atmosphere of 60 ° C. and 95% RH are visually observed. The case where deterioration phenomena such as whitening and cracking were clearly observed in the layer was evaluated as x.

<Electromagnetic shielding performance>Advantest's electromagnetic shielding effectiveness measuring device TR
Using the −17301, the electric field shielding effect at a frequency of 100 MHz (d
B) was measured.

As is clear from the results in Table 1, each of the transparent conductive moisture-permeable films of Examples 1 to 6 of the present invention was the same as that of Comparative Example 1.
Compared to the moisture-permeable films of No. 1 to No. 4, they have improved moisture permeability and good electromagnetic wave shielding properties, are satisfactory in terms of transparency, and have good durability. It turns out to be something.

Next, an EL light emitting device A shown in FIG. 3 and an EL light emitting device B shown in FIG. 4 were manufactured in the following manner using the transparent conductive moisture-permeable film according to Examples 1 and 2 described above. did.

<Manufacture of EL Light-Emitting Device A> As shown in FIG. 3, a transparent substrate 6 made of 75 μm-thick PET film and a transparent conductive layer 7 made of ITO having a thickness of about 400 ° formed on one surface. The conductive layer 7 of the substrate 8
A coating material in which a phosphor powder (which emits blue-green light) is dispersed in a 30% by weight solution of cyanoethyl pullulan in acetone is applied thereonto, dried at 120 ° C. for 30 minutes, and then further dried at 120 ° C., 1 × 10 ^−. Vacuum drying was performed in an atmosphere of ² Torr for 6 hours to form a light emitting layer 9 having a thickness of 40 μm.

On the other hand, a coating of barium titanate powder dispersed in a 30% by weight acetone solution of cyanoethyl pullulan (a coating of barium titanate powder and cyanoethyl pullulan) was coated on the aluminum surface of an aluminum foil 11 having an insulating layer 10 on one side having a thickness of 200 μm. After applying 1: 1), the weight ratio is 60 at 120 ° C.
By heating for minutes, an insulating layer 12 having a thickness of 40 μm was formed.

Next, the conductive substrate 8 and the aluminum foil 11 were overlapped so that the insulating layer 12 and the light emitting layer 9 faced each other, and were joined through a roll laminator heated to 175 ° C. A polyamide water-trapping film 13 having a thickness of about 100 μm is disposed on the conductive substrate 8 of the joined body to form an EL light-emitting element, and the transparent conductive moisture-permeable film of Example 2 is further placed thereon. Cover, the entire periphery (5mm from the periphery)
Was pressed on an aluminum foil 11 under the conditions of 140 ° C. and 30 kg / cm ² for 5 minutes and fused to fabricate an EL light emitting device A having a structure shown in FIG.

This EL light-emitting device A did not show adhesion of foreign matter or dust due to charging, had a good appearance, had excellent sealing properties, and did not cause malfunction due to charging during use. The same results as above were obtained when the transparent conductive moisture-permeable film of Example 1 was used.

<EL Light-Emitting Device B> In the transparent conductive moisture-permeable film of Example 2, the heat-sensitive adhesive layer 4 is formed as shown in FIG. (5 mm area from the edge), and the EL light emitting device A is formed at the center on the second layer 3 of this film.
The light emitting layer 9 similar to the case of the above was formed.

Next, this film and an aluminum foil 11 having an insulating treatment layer 10 on the back surface on which an insulating layer 12 similar to that of the EL light emitting device A is formed, are superposed so that the light emitting layer 9 and the insulating layer 12 face each other. , 140 ° C., under a condition of 30kg / cm ² 5 minutes pressurized adhered, to produce an EL light emitting device B having the structure shown in Figure 4.

This EL light emitting device B also did not show any adhesion of foreign matter or dust due to charging, had a good appearance, was excellent in sealing properties, and did not cause malfunction due to charging during use.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing an example of the transparent conductive moisture-permeable film of the present invention, FIG. 2 is an explanatory view showing a method of testing the moisture-permeable property of the film, FIG. FIG. 4 is a cross-sectional view showing two examples of the EL light emitting device of the present invention manufactured using the above-mentioned film. 1 ... transparent film base material 2 ... transparent conductive layer (first layer) 3 ... transparent metal oxide layer (second layer) 4 ... transparent adhesive layer

Claims (3)

(57) [Claims] 1. A first layer comprising a transparent conductive layer is provided on a transparent film substrate, and a first layer comprising at least one metal oxide selected from Ta, Al, and Zr is further provided thereon. A transparent conductive moisture-permeable film provided with a second layer. 2. A first layer comprising a transparent conductive layer comprising a mixture of indium oxide and tin oxide and having a thickness of 100 to
4,000Å and the thickness of the transparent second layer is 50-2,000Å
The transparent conductive moisture-permeable film according to claim 1, wherein: 3. An EL light-emitting device comprising an EL light-emitting element covered and sealed with the transparent conductive moisture-permeable film according to claim 1 or 2.