JP2545116B2 - Transparent conductive laminate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transparent electroconductive laminate useful as a transparent electrode of each of the above-mentioned elements in a display device using an electroluminescence element, an electrochromic element or the like.

[Conventional technology]

In electroluminescent elements and electrochromic elements, a transparent electrode is used at least on the display side.As such a transparent electrode, in the past, indium oxide, tin oxide, etc. were formed on a base film made of a transparent plastic film. The transparent conductive laminate provided with the transparent conductive thin film is used in many cases.

Such a transparent conductive laminate is, for example, in an organic dispersion type electroluminescence element, a silver paste for a lead electrode and a material for an organic dispersion type light emitting layer are sequentially screen-printed on the transparent conductive thin film of this laminate. Then, after each printing, after heating and drying as required, a lead electrode and a light emitting layer having a predetermined pattern are formed, and a back electrode is laminated on the light emitting layer via an appropriate insulating layer (dielectric layer). ,
The electroluminescence element is configured.

[Problems to be Solved by the Invention]

However, the above-mentioned conventional transparent conductive laminate has a tendency to shrink due to thermal stress, and as a result of this shrinkage occurring in the heating and drying step when forming the lead electrode or the light emitting layer, it is delicate for screen printing. The display performance is deteriorated in a display device such as an electroluminescence element for which precise pattern formation is desired, particularly in a large display device.

Further, the above-mentioned conventional transparent conductive laminate has a high haze value, which causes a reduction in visibility in a display device such as an electroluminescence element, which also causes a reduction in display performance.

Therefore, the present invention has a low haze value and is unlikely to cause shrinkage due to heating as described above, and when applied to a transparent electrode such as an electroluminescent element or an electrochromic element, has a display performance higher than that of a conventional one. It is an object of the present invention to provide a transparent conductive laminate that can provide a display device that is far superior.

[Means for solving the problem]

In the process of earnestly studying for achieving the above-mentioned objects, the inventors of the present invention firstly attribute the haze value and shrinkage due to heating of the conventional transparent conductive laminate to the transparent plastic film used as the base film. That is, it has been known that an additive component such as a lubricant in the film causes diffusion of light to increase the haze value of the film itself, and that the film is apt to cause heat shrinkage.

Therefore, based on this finding, as a result of further trial-and-error experimental study on factors such as the material composition of the plastic film and the film manufacturing method, the specific haze determined by the factors described above as the plastic film was determined. By using one having a value and a heat shrinkage factor,
That is, by forming a transparent electroconducting thin film on this film as a base film, it has a low haze value and is less likely to cause shrinkage due to heating, and as a transparent electrode for an electroluminescence element or an electrochromic display element. The inventors have found that a useful transparent electroconductive laminate can be obtained, and have completed the present invention.

That is, the present invention has a haze value of 1% or less, and
The present invention relates to a transparent conductive laminate, in which a transparent conductive thin film is formed on at least one surface of a transparent plastic film having a heat shrinkage rate of 0.5% or less under heating conditions of 150 ° C. for 30 minutes.

[Structure and operation of the invention]

The transparent plastic film used in the present invention has a haze value of 1% or less and a temperature of 150 ° C. as described above.
The heat shrinkage rate when heated for 30 minutes in both the vertical and horizontal directions is 0.5% or less, and the haze value and the same heat shrinkage rate of the transparent plastic film used for the conventional transparent conductive laminate are about each. 2-4% and about 2-5%
Compared with the above, the haze value is low and the shrinkage due to heating is extremely suppressed.

The haze value is expressed as a ratio of diffuse transmitted light to total transmitted light when the film is irradiated with visible light, and in this specification, the total light transmittance and the diffuse transmittance are measured in Japan. Using an automatic digital haze meter (NDH-20D) manufactured by Denshoku Industries Co., Ltd.,
The following formula; Calculated according to the above. The smaller the haze value, the better the transparency of the film.

Further, the heat shrinkage rate, using a test film cut into a size of 50 mm in both length and width, to measure the vertical and horizontal dimensions after the heating test, as the shrinkage length the difference between this and the dimensions before the heating test, The following formula; Therefore, the heat shrinkage ratios in the vertical and horizontal directions are calculated. In this specification, when the heat shrinkage rate is 0.5% or less without displaying the vertical and horizontal directions, both the vertical and horizontal directions
This means that the heat shrinkage rate is 0.5% or less.

In general, a transparent plastic film is formed by subjecting a plastic material to film formation by various known processing means such as extrusion, and then undergoing necessary steps such as stretching, but the above plastic material has various purposes. Additives such as lubricants, catalysts and promoters are often added.

The transparent plastic film of the present invention is, for example, a processing film (lipids such as titanium oxide and calcium carbonate) among the above-mentioned additive components which is minimized and which is produced by the above-mentioned known method using this molding material ( This can be obtained by further subjecting a commercially available film) to specific heat setting.

The above-mentioned heat setting is to heat to a temperature close to the melting point of the plastic material and gradually cool it while applying a tension, that is, to cool it slowly to room temperature. The heating temperature differs depending on the plastic material, so it cannot be determined in a general manner, but it is generally good to set it in the range of 180 to 220 ° C, and in the case of polyethylene terephthalate known as the most representative plastic material, the range of 190 to 200 ° C is particularly desirable. It is suitable.
A heating time of about 1 to 10 minutes is usually sufficient.

Examples of the plastic material usable in the present invention include polyesters such as polyethylene terephthalate, polysulfone, polyether sulfone,
Examples thereof include polypropylene, polycarbonate, polyamide, polyimide, triacetate and the like, and those having heat resistance of 100 ° C. or higher are preferably used.

The transparent plastic film of the present invention may be produced by a method different from the above as long as the haze value and the heat shrinkage rate under the heating condition of 150 ° C. for 30 minutes satisfy the above requirements. The thickness of the film is not particularly limited, but it is generally preferable that the film has a thickness of about 50 to 200 μm.

In the present invention, as the transparent conductive thin film formed on at least one surface of the base film made of the transparent plastic film, indium oxide, tin oxide, a mixed oxide thereof, a mixed oxide of tin oxide and antimony oxide, etc. Oxide thin film consisting of, metal thin film such as gold, silver, copper, platinum, palladium, aluminum, indium, tin, cadmium, zinc, or a laminated thin film in which the above oxide thin film and metal thin film are preferably laminated in this order. Can be mentioned. Among these, a laminated thin film obtained by laminating a palladium thin film on a mixed oxide thin film of indium oxide and tin oxide is most preferable in terms of transparency, conductivity and adhesion to a film substrate.

Means for forming each of these thin films is arbitrary, and a known thin film forming technique such as a vacuum deposition method, a sputtering method, or an ion plating method can be arbitrarily adopted. The film thickness is usually 100 to 1,000 for oxide thin films.
Å, usually 10 to 200Å for metal thin film, it is suitable to have transparency depending on each thin film forming material and the surface electric resistance after forming thin film is usually 100 to 1,000Ω / □. Is set.

FIG. 1 shows an example of a transparent electroconductive laminate of the present invention comprising the above components. In the figure, 1 is the specific transparent plastic film described above, 2 is this film 1
Is a transparent conductive thin film composed of a laminated thin film of an oxide thin film 2a and a metal thin film 2b formed on one surface of the.

FIG. 2 shows an example in which the transparent conductive laminate of FIG. 1 is applied as a transparent electrode of an electroluminescent element. That is, transparent plastic film 1
A silver paste for a lead electrode and a material for an organic dispersion type light emitting layer are sequentially screen-printed on the thin film 2 of the transparent conductive laminate 3 composed of the transparent conductive thin film 2 and the required heat drying after each printing. After that, the lead electrode 4 and the light emitting layer 5 having a predetermined pattern are formed, and the back electrode 7 is laminated on the light emitting layer 5 with the insulating layer (derivative layer) 6 interposed therebetween, thereby forming an electroluminescence element. It was made to let.

In the electroluminescent element having such a structure, since the transparent conductive laminate 3 used is less likely to cause shrinkage due to heating due to the low heat shrinkability of the transparent plastic film 1, the lead electrode 4 The screen printing of the light emitting layer 5 and the light emitting layer 5 shows almost no deviation, and the haze value of the film is low and the visibility is not deteriorated. Therefore, when this element is incorporated into a display device, a very excellent display performance is obtained. Is obtained.

〔The invention's effect〕

As described above, according to the present invention, the haze value is low and it is difficult to cause shrinkage due to heating, and when applied to a transparent electrode such as an electroluminescence element or an electrochromic element, it is far more displayed than the conventional one. It is possible to provide a transparent conductive laminate that can provide a display device with excellent performance.

〔Example〕

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

Example Using a polyethylene terephthalate film [Tetoron film manufactured by Teijin Ltd., O type; haze value 0.3%] having a thickness of 75 μm, this film was heated at 200 ° C. for 3 minutes and then gradually cooled while being subjected to tension. . The obtained film had a heat shrinkage ratio of 0.4% in the longitudinal direction and 0.1% in the transverse direction under the heating condition of 150 ° C. for 30 minutes.

Next, the above-mentioned low heat shrinkable film was attached as a base material film to the substrate side of the sputtering device, and an alloy target consisting of 90% by weight of indium and 10% by weight of tin was mounted on the sputtering electrode, and up to 1 × 10 ^-3 Pa. After evacuation, 100 cc / min of argon gas and 15 cc / min of oxygen gas were introduced to keep the inside of the apparatus at 4 × 10 ⁻¹ pa. In this state, a DC voltage of 400 V was applied to the above-mentioned sputter electrode to cause glow discharge, and spattering was performed for 30 seconds, that is, by performing reactive magnetron spattering, indium oxide and tin oxide on one side of the low-shrinkage film. An oxide thin film with a thickness of 200Å made of mixed oxide with was formed.

Then, using the above-mentioned sputtering device as it is, except that the target was changed to palladium and only argon gas was allowed to flow in, the sputtering was performed for 3 seconds in the same manner as described above to obtain the thickness on the oxide thin film. But
A metal thin film composed of a 20Å palladium thin film was formed.

A transparent conductive laminate having the structure shown in FIG. 1, which is composed of the transparent plastic film made of polyethylene terephthalate thus obtained and the transparent conductive thin film made of the oxide thin film and the metal thin film formed thereon, , Its surface electric resistance is 300Ω / □, and the light transmittance at 550nm is 82.
%, The haze value was 0.8%, and the heat shrinkage percentage under the heating condition of 150 ° C. for 30 minutes was 0.4% in the longitudinal direction and 0.1% in the lateral direction.

Next, an electroluminescent element was produced by the following method using this transparent conductive laminate. First, a silver paste was screen-printed on the transparent conductive thin film of the above laminated body, and dried by heating at 150 ° C. for 30 minutes to form a lead electrode having a thickness of 40 μm. Then, a liquid obtained by dispersing the phosphor powder in an acetone solution of cyanoethyl cellulose as a binder is screen-printed on the above-mentioned thin film, and at 120 ° C. at 120 ° C.
After heating for 1 minute, the temperature was raised to 150 ° C. and heating was performed for 2 minutes to form a phosphor layer having a thickness of 60 μm. As the phosphor powder, a powder containing zinc sulfide as a main component was used, and the weight mixing ratio of this powder and cyanoethyl cellulose was 84: 1.
It was set to 6.

After that, the above-mentioned phosphor layer was coated with a dispersion of barium titanate powder in the same acetone solution of cyanoethyl cellulose as described above. The weight mixing ratio of barium titanate powder and cyanoethyl cellulose was 1: 1. After that, after heating for 120 minutes at 60 ℃ to remove most of the acetone, put an aluminum foil with a thickness of 200 μm, raise the temperature to 150 ℃ together with this aluminum foil and heat for 2 minutes. An electroluminescent element having a structure shown in FIG. 2 was obtained in which an insulating layer having a thickness of 40 μm was formed and an aluminum foil as a back electrode was closely adhered and integrated on the insulating layer.

In this device, the thermal shrinkage of the transparent conductive laminate during the heating process is small, so that the print displacement of the lead electrodes and the light emitting layer is 0.1%.
% Or less, and no decrease in transparency on the display side (transparent electrode side) was observed, and it was confirmed that a display device incorporating the same exhibits excellent display performance.

Comparative Example Performed except that a polyethylene terephthalate film having a thickness of 75 μm (Tetoron film manufactured by Teijin Ltd., S type; haze value 2%) was used as it was, that is, without heat setting treatment at 200 ° C. for 3 minutes. Exactly the same as the example 1
A transparent conductive laminate having the structure shown in the figure was obtained.

The heat shrinkage of the above base material film under the heating conditions of 150 ° C. and 30 minutes was 3% in the longitudinal direction and 1.5% in the lateral direction. The surface electric resistance of the obtained laminate is 300Ω / □, 550nm
The light transmittance at 80%, the haze value at 2.2%, and 1
The heat shrinkage rate under the heating condition of 50 ℃ for 30 minutes was 2.8% in the longitudinal direction and 1.4% in the transverse direction.

Next, using this transparent conductive laminate, an electroluminescence element was produced in the same manner as in the example. The print displacement of the lead electrodes and the light emitting layer was as large as 2%,
In addition, the transparency on the display side was greatly impaired, and the display device incorporating this was remarkably inferior in display performance to those of the examples.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of the transparent conductive laminate of the present invention, and FIG. 2 is a cross-sectional view showing a constitutional example of an electroluminescence element produced by using the laminate. 1 ... Transparent plastic film, 2 (2a, 2b) ... Transparent conductive thin film, 3 ... Transparent conductive laminate

Claims (1)

(57) [Claims] 1. A transparent conductive thin film formed on at least one side of a transparent plastic film having a haze value of 1% or less and a heat shrinkage rate of 0.5% or less under heating conditions of 150 ° C. and 30 minutes. Conductive laminate.