JP4961858B2 - Film with transparent conductive layer, flexible dispersive electroluminescence element, and electronic device using the same - Google Patents

Description

  The present invention relates to a film with a transparent conductive layer in which a transparent conductive layer mainly composed of conductive oxide fine particles and a binder matrix is formed on an extremely thin base film, and a dispersion type obtained using the film with the transparent conductive layer BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescence element and an electronic device using the electroluminescence element, and particularly relates to a distributed electroluminescence element applied as a light emitting element incorporated in a key input part of various devices such as a mobile phone, and an electronic device using the same It is.

A dispersive electroluminescence element (hereinafter abbreviated as “dispersion EL element”) is a light emitting element driven by an alternating voltage, and has been conventionally used for backlights of liquid crystal displays such as mobile phones and remote controllers. I came.
Originally, the light emitting element facilitates operation in dark places such as at night, so new applications in recent years include mobile information terminals such as mobile phones, remote controllers, PDAs (Personal Digital Assistance), laptop PCs, etc. Attempts have been made to incorporate distributed EL elements into key input components (keypads) of various devices.
By the way, a light emitting diode (LED) has been applied as a light emitting element of the conventional key input component (keypad). However, the LED is a point light source, and the brightness of the keypad part is uneven and the appearance is generally poor. White and blue light emission colors are preferred, but LEDs have problems such as high cost and high power consumption compared to dispersive EL elements. The movement which employ | adopts a type | mold EL element is flourishing (for example, refer patent document 1).

As a manufacturing method of such a dispersion type EL element, generally, a physical film formation method such as sputtering or ion plating is used, and a transparent conductive layer (hereinafter referred to as “sputtering”) of indium tin oxide (hereinafter referred to as “ITO”). A method of further forming a phosphor layer, a dielectric layer, and a back electrode layer on a plastic film (hereinafter abbreviated as “sputtering ITO film”) on which an ITO layer is abbreviated by screen printing or the like. Widely known.
Here, the sputtering ITO film has an ITO single layer, which is an inorganic component, on a transparent plastic film such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN). Thus, it is possible to obtain a transparent conductive layer having a low resistance with a surface resistance value of about 100 to 300 Ω / □ (ohms per square).

  However, the sputtered ITO layer is a thin film of an inorganic component and is extremely brittle. Therefore, there is a problem in that microcracks are easily generated. For this reason, it is necessary to provide the plastic film as the base material with sufficient strength and rigidity, and the thickness is at least 50 μm or more, usually 75 μm or more.

  Moreover, PET film is widely used as the base film of the above-mentioned sputtering ITO film. However, when the thickness is less than 50 μm, the flexibility of the base film is too high, and sputtering is performed during handling. Since the ITO layer is easily cracked and the conductivity of the film is remarkably impaired, for example, a thin sputtered ITO film having a thickness of 25 μm, for example, has not been put into practical use for devices that require high flexibility. there were.

Furthermore, in order to improve the handling, an attempt was made to form a sputtering ITO layer on the base film using a base film less than 50 μm thick lined with a support film having a thickness of about 75 μm to 125 μm. Even in this case, since the flexibility of the sputtering ITO layer itself is poor, there has been a problem that when the support film is peeled and removed, the conductive properties and flexibility of the sputtering ITO layer cannot be achieved at the same time.
Moreover, even if the soft base film such as urethane has a film thickness of 75 μm or more, the present situation is that cracks are likely to occur when a sputtering ITO layer is formed and has not been put into practical use.

By the way, as the characteristics required when the distributed EL element is applied to the keypad, for example, as disclosed in Patent Document 1, in addition to the uniformity of brightness and the low power consumption, the keypad's keystroke durability and further It is important to have excellent click feeling when operating the keypad.
In particular, it is necessary to sufficiently increase the flexibility of the dispersion type EL element itself so that the click feeling is not impaired by incorporating the dispersion type EL element in the keypad, and more specifically, the thickness of the EL element can be made as much as possible. It is necessary to use a base film made of a thin or flexible material.

  However, as described above, when a dispersive EL element is manufactured using a conventional sputtering ITO film, the thickness of the base film is increased to at least 50 μm to increase the rigidity of the film in order to prevent the sputtering ITO layer from cracking. In addition, since the base film made of a flexible material cannot be used, when applied to the above keypad, the keystroke durability is still insufficient and the click feeling of key operation Is not good enough.

Therefore, instead of forming the ITO layer by sputtering, for example, as a method for forming a relatively flexible transparent conductive layer on a plastic base film, a transparent electrode mainly composed of acicular conductive oxide fine particles and a binder There is a method of applying (printing), drying, and curing a transparent electrode layer forming paste mainly composed of a conductive polymer such as a layer forming paste or polyethylenedioxythiophene / polystyrene sulfonic acid (PEDOT / PSS) on a base film. It is known (for example, see Patent Documents 2 to 4).
In addition, as a method for forming a flexible transparent conductive layer different from the above, for example, as disclosed in Patent Documents 5 to 9, a coating solution for forming a transparent electrode layer containing conductive oxide fine particles and a binder as main components, A method is known in which after coating and drying on a base film, a compression (rolling) treatment with a metal roll is performed, and then the binder component is cured. This method has the advantage that the packing density of the conductive fine particles in the transparent conductive layer can be increased by rolling with a metal roll, and the electrical (conductive) characteristics and optical characteristics of the film can be greatly increased.

  In order to obtain excellent characteristics such as a click feeling of key operation by the method of forming a transparent electrode layer by these conventional coating methods, it is necessary to set the thickness of the base film to be thin, for example, 25 μm or less, preferably 9 μm. It is necessary to use: In addition, these base films are used by being backed by a support film having a thickness of about 100 μm having a slightly adhesive layer that can be peeled off at the interface with the base film. This makes it easier to handle, prevent warping (curling) of the base material due to the laminated structure of EL elements, and to make the laminated printing uniform and protect the EL elements during transportation and handling. is there.

Here, as a problem related to the keypad, for example, Patent Document 10 points out the destruction / failure of LCD (liquid crystal) parts and the like due to static electricity generated during key input of a cellular phone. For this reason, the same problem may occur in the key input component of the dispersion type EL element. As a countermeasure, for example, a method of releasing the static electricity by forming a transparent conductive layer on the outer surface of the dispersion type EL element can be cited. However, since the base film for the keypad has high flexibility as described above, the conventional sputtering ITO film cannot be applied. In addition, it has not been easy to inexpensively form a transparent conductive layer satisfying the durability (spot durability), transparency, and conductivity required for the keypad on the outer surface of the dispersed EL element.
JP 2001-238331 A JP-A-6-309922 JP 9-35873 A JP 11-273874 A JP-A-4-237909 JP-A-5-036314 JP 2001-321717 A JP 2002-36411 A JP 2002-42558 A JP 2002-232537 A

  The present invention has been made in view of such a conventional situation, and is a transparent conductive film that is superior in flexibility to a conventional sputtering ITO film and a dispersion type EL element using the film, and also has a countermeasure against static electricity. A film with a layer and a flexible dispersion type EL element, specifically, a film with a transparent conductive layer having a good handling property while using an extremely thin base film, a flexible dispersion type EL element using the film with a transparent conductive layer, and An object of the present invention is to provide a manufacturing method thereof and an electronic device using the same.

  In order to achieve the above object, a film with a transparent conductive layer provided by the present invention is a film with a transparent conductive layer in which a transparent conductive layer is formed on a base film by a coating method. On the layer side, a support film having a slightly adhesive layer that can be peeled off at the interface with the transparent conductive layer is lined, the thickness of the base film is 3 to 25 μm, and the transparent conductive layer is conductive It is characterized by comprising oxide fine particles and a binder matrix as main components and being subjected to compression treatment.

  In addition, the other film with a transparent conductive layer provided by the present invention has a peeling strength between the fine adhesive layer and the transparent conductive layer (a force required for peeling per unit length in the peeling portion) by heat treatment. Regardless of the presence or absence of a process, it is 1-15 g / cm, The dimensional change rate (thermal contraction rate) of the vertical direction and the horizontal direction of the said film with a transparent conductive layer is 0.3% or less. The base film has a thickness of 3 to 9 μm, and the conductive oxide fine particles contain at least one of indium oxide, tin oxide, and zinc oxide as a main component. The conductive oxide fine particles mainly composed of indium oxide are indium tin oxide fine particles, and the binder matrix is cross-linked and has resistance to organic solvents. thing Characterized, the compression process is characterized in that which is performed by the rolling treatment of the metal roll.

  Furthermore, the flexible dispersive electroluminescent element provided by the present invention includes at least a transparent electrode layer, a phosphor layer, a dielectric layer, and a back electrode layer on the surface of the film with the transparent conductive layer on which the transparent conductive layer is not formed. After the formation, the support film having the slightly adhesive layer is peeled off at the interface between the transparent conductive layer and the slightly adhesive layer formed on the base film.

  The electronic device provided by the present invention is characterized in that the flexible dispersive electroluminescent element is applied as a light emitting element incorporated in a key input component of the device, and the electronic device is a mobile phone, a remote It is a controller and a portable information terminal.

According to the present invention, a film with a transparent conductive layer and a flexible dispersive EL element, which are superior in flexibility to a conventional sputtered ITO film and a dispersive EL element using the film, and are provided with a countermeasure against static electricity, are provided at low cost. can do.
In addition, when the above-described flexible distributed EL element is applied to a keypad of a mobile phone or the like, it has sufficient keying durability in practical use, and at the same time, good key operation without any special structure or device on the keypad It becomes possible to obtain a click feeling.

  As shown in FIG. 1, the conventional dispersion type EL element has at least a transparent electrode layer 2, a phosphor layer 3, a dielectric layer 4, and a back electrode layer 5 that are sequentially formed on a transparent plastic film 1. In application to an actual device, as shown in FIG. 2, it is common to further form and use a collector electrode 6 made of silver or the like and an insulating protective layer 7.

On the other hand, in the flexible dispersion type EL device of the present invention, as shown in FIG. 4, the transparent conductive layer 8 formed on one surface of the base film 9 is backed by a support film 10 having a slightly adhesive layer. The transparent electrode layer 2, the phosphor layer 3, the dielectric layer 4, and the back electrode layer 5 that are sequentially formed on the base film of the transparent conductive layer-coated film (FIG. 3). As shown in FIG. 5, the support film is used in such a form that a support film having a slightly adhesive layer is peeled and removed at the interface between the base film and the slightly adhesive layer.
Although not shown in FIG. 4, there is a slightly adhesive layer between the support film and the base film. As described above, the slightly adhesive layer is peeled off together with the support film when the support film is peeled off. The Although it cannot be said that it is general, when the support film material itself has slight adhesiveness, the support film also has the function of a slightly adhesive layer, and therefore it is not particularly necessary to form the slightly adhesive layer on the support film.
Moreover, although not shown in FIG. 5, it is common to further form and use a collector electrode, such as silver, and an insulating protective layer similarly to FIG.

As described above, in the film with a transparent conductive layer and the flexible dispersion type EL element of the present invention, since the transparent conductive layer is formed on the surface of the base film on which the support film is lined, the above-mentioned device component due to static electricity. Can be effectively prevented.
As described above, in the film with a transparent conductive layer and the flexible dispersion type EL element of the present invention, since the support film is lined on the transparent conductive layer formed on the base film, the thickness of the base film itself is set thin. In addition, if the material of the base film is appropriately selected, good flexibility can be imparted to the dispersive EL element.
The role of the support film used in the present invention is to facilitate the handling in the production process of the flexible dispersion type EL element of the present invention, and the base material in the lamination process of the phosphor layer, the dielectric layer, the back electrode layer, etc. Work to prevent warping (curl), work to protect the film with transparent conductive layer and dispersion type EL element during transportation and handling, and evenly print the transparent conductive layer, phosphor layer, dielectric layer, back electrode layer, etc. Function to perform (Generally, in screen printing, a suction stage with a large number of small-diameter holes is used, and the holes are decompressed to fix the film. Deformation and a dent is formed, and a mark of the dent is generated on the screen-printed film).

Here, it is preferable that the support film used in the present invention has a thickness of 50 μm or more, preferably 75 μm or more, more preferably 100 μm or more. If the thickness of the support film is less than 50 μm, the rigidity of the film is lowered, handling in the manufacturing process of the above-described dispersion type EL element, warping of the substrate (curl), phosphor layer, dielectric layer, back electrode layer, etc. This is because a problem is likely to occur in the printability and the like. In addition, the flexible dispersive EL element of the present invention is subjected to a half-cut treatment so that only the dispersive EL element portion having a predetermined shape can be peeled off from the backing film at the end of the production process. If the thickness is less than 50 μm, there is a problem that half-cut processing cannot be performed well. The half-cut treatment is a method of cutting only the dispersion EL element portion including the base film according to the element shape using a mold press or the like in the dispersion EL element backed by the support film. Since a part of the backing support film is also cut, the support film is required to have a predetermined thickness as described above.
On the other hand, the thickness of the support film used in the present invention is preferably 200 μm or less. When it exceeds 200 μm, the support film is hard and heavy, and it is difficult to handle, and at the same time, it is not preferable in terms of cost.

  The support film used in the present invention does not require transparency, and the material thereof is not particularly limited, and various plastics can be used. Specifically, polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), nylon, polyethersulfone (PES), polyethylene (PE), polypropylene (PP), urethane, fluororesin, polyimide ( A plastic such as PI) can be used. Among these, a PET film is preferable from the viewpoints of being inexpensive, excellent in strength, and having flexibility.

The support film used in the present invention undergoes a production process of a film with a transparent conductive layer and a dispersion-type EL element while in close contact with the transparent conductive layer formed on the base film, and finally peels from the transparent conductive layer of the base film. Therefore, generally, an acrylic or silicone-based slightly adhesive layer is applied and formed on one side. A silicone-based slightly adhesive layer is preferable in that it has excellent heat resistance.
Here, the slightly adhesive layer used in the present invention has a peel strength (force required for peeling per unit length at the peeled portion in a T-type peel test [tensile speed = 300 mm / min]) of 1 to 15 g / cm. Preferably, it is in the range of 2 to 10 g / cm, more preferably 2 to 6 g / cm. When the peel strength is less than 1 g / cm, even if the support film and the transparent conductive layer of the base film are bonded, it is not preferable because the film is easily peeled off in the manufacturing process of the film with a transparent conductive layer and the dispersion type EL element. If it exceeds 15 g / cm, the transparent conductive layer of the support film and the base film is difficult to peel off, making it difficult for the flexible dispersive EL element to peel from the support film, degrading the workability of the EL element peeling process, and forcing it off. This is because there is a high risk that the element will stretch, the transparent conductive layer will deteriorate (cracks, etc.), and a part of the slightly adhesive layer will adhere to the base film surface.
By the way, as described later, the flexible dispersion type EL element of the present invention is produced through several heat treatment steps (usually about 120 to 140 ° C.) with respect to the film with a transparent conductive layer, and thus undergoes these treatment steps. It is necessary to maintain the peel strength afterwards, and for this purpose, the material of the fine adhesive layer is required to have heat resistance. Moreover, since an ultraviolet curing process may be applied at the time of manufacture of a film with a transparent conductive layer, the ultraviolet-ray resistance is also required for the material of the slightly adhesion layer in that case.

The base film used in the present invention needs to have a thickness of 3 to 25 μm, preferably 3 to 16 μm, and more preferably 3 to 9 μm. This is because when the thickness of the base film exceeds 25 μm, its rigidity increases, and it is difficult to obtain a good click feeling when incorporated into the keypad as a flexible dispersive EL element. Further, it is more preferable that the thickness of the base film is 9 μm or less because not only a better click feeling can be obtained but also the thickness of the dispersion type EL element itself can be reduced.
On the other hand, if the thickness of the base film is less than 3 μm, it is difficult to obtain a general-purpose film that is generally available, and it becomes difficult to handle the base film itself, making it difficult to form a transparent conductive layer or to back it with a support film. In other words, since the strength of the base film itself is lowered, damage is caused to the constituent elements of the element including the transparent conductive layer and the phosphor layer of the dispersion type EL element when used by being incorporated in a key input part of the device. This is not preferable because there are problems such as that.
The material of the base film used in the present invention is not particularly limited as long as it is translucent and a transparent conductive layer can be formed thereon, and various plastics can be used. Specifically, plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), nylon, polyethersulfone (PES), polycarbonate (PC), polyethylene (PE), polypropylene (PP), urethane, fluorine resin, etc. Can be used. Among these, a PET film is preferable from the viewpoints of being inexpensive, excellent in strength, having both transparency and flexibility.
As the base film, a film reinforced with visible and light-transmitting inorganic and / or organic (plastic) fibers (including needles, rods, and whisker particles) and flaky particles (including plates) may be used. A base film reinforced with fibers or flaky fine particles can have a good strength even with a thinner film.
As shown in FIG. 3, the film with a transparent conductive layer according to the present invention forms a transparent conductive layer 8 on one surface of a base film 9. Since the transparent conductive layer 8 is for the purpose of preventing various harmful effects due to static electricity, it may be much higher than the resistance value of the transparent conductive layer described above applied as an electrode of a dispersion type EL element. The value is preferably about 1 × 10 ⁶ ) Ω / □ or less.
The transparent conductive layer 8 is formed by coating on the base film 9 using a coating solution for forming a transparent conductive layer in which conductive oxide fine particles are dispersed in a solvent containing a binder component. From the viewpoint of preventing as much as possible, it is preferable to have a high transmittance. Therefore, the film thickness is preferably 3 μm or less, and more preferably 1 μm or less.
The material of the binder used for the transparent conductive layer 8 is not particularly limited as long as it has good adhesion to the base film 9 and has transparency and predetermined conductivity, and various resins can be used. . Specifically, resins such as urethane, epoxy, polyester, and fluorine resin can be used. Among these, urethane-based resins are preferable from the viewpoints of being inexpensive, excellent in transparency, strength, and flexibility.

As described in the description of the peel strength with respect to the fine adhesion layer, the flexible dispersion type EL element of the present invention is manufactured through several heat treatment steps for the transparent conductive layer-attached film, and therefore before and after the heat treatment step. The dimensional change rate (heat shrinkage rate) in the machine direction (MD) and the transverse direction (TD) of the film with a transparent conductive layer is both 0.3% or less, preferably 0.15% or less, more preferably 0.1. % Or less. Here, in the plastic film, the dimensional change rate accompanying the heat treatment generally indicates a shrinkage rate. For example, in the biaxially stretched PET film, the shrinkage rate in the machine direction (MD) of the heat treatment is in the transverse direction (TD). The value is several times larger than the shrinkage rate.
When the dimensional change rate in either the vertical direction (MD) or the horizontal direction (TD) exceeds 0.3%, each layer such as a phosphor layer, a dielectric layer, and a back electrode layer on the film with a transparent conductive layer In each laminating process in which the paste for forming each layer is formed by pattern printing, drying and heat-curing sequentially, dimensional changes (shrinkage) occur at each heat-curing treatment, resulting in print misalignment. Is larger than the allowable range in the manufacture of the dispersion type EL element.
Therefore, it goes without saying that even if the dimensional change rate of the transparent conductive layer-attached film is 0% (not at all), it is within the scope of the technical idea of the present invention.
As a method for reducing the dimensional change rate, a method using a low heat shrink type support film or base film that has been heat shrunk in advance, a method of heat shrinking together with a film with a transparent conductive layer, and the like are conceivable, but not limited thereto. . If these methods are applied appropriately, the dimensional change rate of the film with a transparent conductive layer during the heat treatment step can be reduced, and at the same time, the film with a transparent conductive layer resulting from the difference in the dimensional change rate between the support film and the base film Further, it is possible to suppress warpage (curl) in the flexible dispersed EL element lined with a support film.

The formation of the transparent conductive layer mainly composed of the conductive oxide fine particles and the binder matrix on the base film can be performed as follows using the forming methods described in Patent Documents 5 to 9.
In the first method, a coating liquid for forming a transparent conductive layer in which conductive oxide fine particles are dispersed in a solvent containing a binder component is applied and dried on a single base film having a thickness of 3 to 25 μm or less. After this, the coating layer is subjected to compression treatment, and then the binder component is cured. Thereafter, a support film is lined on the transparent conductive layer formed on the base film.
The second method is to apply a coating solution for forming a transparent conductive layer in which conductive oxide fine particles are dispersed in a solvent containing a binder component onto a base film having a thickness of 3 to 25 μm or less lined with a support film. After drying to form a coating layer, this coating layer is compressed together with the base film backed with a support film, and then the binder component of the compression-treated coating layer is cured to form a transparent conductive layer on the base film. To do. Thereafter, the base film on which the transparent conductive layer is formed is once peeled off and the transparent conductive layer side is backed with a support film.
The first method is simple and preferable, but the second method can be applied when it is difficult to handle alone because the base film is thin. Further, in the second method, since the base film backed by the support film is used, even if the above-described compression treatment is performed on the extremely thin base film, the base film can be effectively prevented from being distorted or wrinkled. .
When the compression treatment is performed, the packing density of the conductive fine particles in the transparent conductive layer increases, so that not only light scattering is reduced to improve the optical characteristics of the film, but also the conductivity can be greatly increased. As the compression treatment, for example, the base film on which the coating liquid for forming the transparent conductive layer is coated and dried may be rolled with a hard chrome-plated metal roll. In this case, the rolling pressure of the metal roll is linear pressure: 29. 4 to 490 N / mm (30 to 500 kgf / cm) is good, and 98 to 294 N / mm (100 to 300 kgf / cm) is more preferable. If the linear pressure is less than 29.4 N / mm (30 kgf / cm), the effect of improving the resistance value of the transparent conductive layer by the rolling treatment is insufficient. If the linear pressure exceeds 490 N / mm (500 kgf / cm), rolling equipment This is because the base film and the support film may be distorted at the same time as the size of the film increases. The rolling pressure (N / mm ² ) per unit area in the rolling process of the metal roll is the nip width (the width of the region where the transparent conductive layer is crushed by the metal roll at the contact portion between the metal roll and the transparent conductive layer). The nip width is about 0.7 to 2 mm if the roll diameter is about 150 mm, although it depends on the diameter and linear pressure of the metal roll.

  In addition, in order to raise the adhesive force with a transparent conductive layer, the said base film can also give an easy-adhesion process, specifically, a plasma process, a corona discharge process, a short wavelength ultraviolet irradiation process, etc. previously. .

  The conductive oxide fine particles applied to the coating liquid for forming a transparent conductive layer used in the present invention are conductive oxide fine particles mainly containing at least one of indium oxide, tin oxide, and zinc oxide. For example, indium tin oxide (ITO) fine particles, indium zinc oxide (IZO) fine particles, indium-tungsten oxide (IWO) fine particles, indium-titanium oxide (ITiO) fine particles, indium zirconium oxide fine particles, tin antimony Examples include oxide (ATO) fine particles, fluorine tin oxide (FTO) fine particles, aluminum zinc oxide (AZO) fine particles, gallium zinc oxide (GZO) fine particles, and the like as long as they have transparency and conductivity. Well, not limited to these. However, among the above, ITO has the highest characteristics and is preferable.

  The average particle diameter of the conductive oxide fine particles used in the present invention is preferably 1 to 500 nm, and more preferably 5 to 100 nm. When the average particle size is less than 1 nm, it is difficult to produce a coating liquid for forming a transparent conductive layer, and the resistance value of the obtained transparent conductive layer is increased. On the other hand, if it exceeds 500 nm, the conductive oxide fine particles are likely to settle in the coating liquid for forming the transparent conductive layer and are not easily handled, and at the same time, the transparent conductive layer can simultaneously achieve high transmittance and low resistance. Because it becomes difficult. The average particle diameter of the conductive oxide fine particles is a value observed with a transmission electron microscope (TEM).

  Here, the binder component of the coating liquid for forming the transparent conductive layer has a function of bonding the conductive oxide fine particles to increase the conductivity and strength of the film, a function of increasing the adhesion between the base film and the transparent conductive layer, and Functions to impart solvent resistance to prevent the deterioration of the transparent conductive layer by the organic solvent contained in various printing pastes used for the formation of phosphor layers, dielectric layers, back electrode layers, etc. in the manufacturing process of the dispersion type EL element Have. As the binder, an organic and / or inorganic binder can be used, and in consideration of the film forming conditions of the transparent conductive layer, the base film to which the coating liquid for forming the transparent conductive layer is applied, so as to satisfy the above role. Can be selected as appropriate.

  As the organic binder used in the present invention, a thermoplastic resin such as an acrylic resin or a polyester resin is not necessarily applicable. However, in general, the organic binder preferably has a solvent resistance and is therefore a crosslinkable resin. And can be selected from a thermosetting resin, a room temperature curable resin, an ultraviolet curable resin, an electron beam curable resin, and the like. For example, epoxy resins and fluorine resins as thermosetting resins, two-part epoxy resins and urethane resins as room temperature curable resins, and resins containing various oligomers, monomers, and photoinitiators as ultraviolet curable resins Examples of the electron beam curable resin include resins containing various oligomers and monomers, but are not limited to these resins.

  Moreover, as an inorganic binder used by this invention, the binder which has a silica sol, an alumina sol, a zirconia sol, a titania sol etc. as a main component can be mentioned. For example, the silica sol may be a polymer obtained by hydrolyzing an orthoalkyl silicate by adding water or an acid catalyst to advance dehydration condensation polymerization, or a commercially available alkyl silicate solution which has already been polymerized to a tetramer to a pentamer. Further, a polymer obtained by further proceeding hydrolysis and dehydration condensation polymerization can be used.

  If the dehydration condensation polymerization proceeds too much, the solution viscosity increases and eventually solidifies. Therefore, the degree of dehydration condensation polymerization is adjusted to be equal to or lower than the upper limit viscosity that can be applied on the transparent substrate. However, the degree of dehydration condensation polymerization is not particularly limited as long as it is a level equal to or lower than the above upper limit viscosity, but considering the film strength, weather resistance and the like, a weight average molecular weight of about 500 to 50,000 is preferable. This alkylsilicate hydrolyzed polymer (silica sol) undergoes almost complete dehydration condensation reaction (crosslinking reaction) upon heating after application and drying of the coating solution for forming the transparent conductive layer, resulting in a hard silicate binder matrix (silicon oxide). A binder matrix containing as a main component. The dehydration condensation polymerization reaction starts immediately after the film is dried, and when the time elapses, the conductive oxide fine particles are hardened so that they cannot move. Therefore, when an inorganic binder is used, the above compression treatment is transparent. It is necessary to carry out as soon as possible after applying and drying the conductive layer forming coating solution.

  An organic-inorganic hybrid binder can also be used as the binder used in the present invention. For example, a binder obtained by partially modifying the above-described silica sol with an organic functional group and a binder mainly composed of various coupling agents such as a silicon coupling agent can be given.

  The transparent conductive layer using the inorganic binder or the organic-inorganic hybrid binder used in the present invention necessarily has excellent solvent resistance, but the adhesion with the base film and the flexibility of the transparent conductive layer It is necessary to select appropriately so as not to deteriorate the properties.

  The ratio of the conductive oxide fine particles and the binder component in the coating solution for forming the transparent conductive layer used in the present invention is that the specific gravity of the conductive oxide fine particles and the binder component is about 7.2 (specific gravity of ITO), respectively. Assuming about 1.2 (specific gravity of a normal organic resin binder), the conductive oxide fine particles: binder component = 85: 15 to 97: 3, preferably 87:13 to 95: 5 is preferred by weight ratio. . The reason is that when the rolling treatment of the present invention is carried out, if the binder component is more than 85:15, the resistance of the transparent conductive layer becomes too high, and conversely if the binder component is less than 97: 3, the strength of the transparent conductive layer is lowered. At the same time, sufficient adhesion with the base film cannot be obtained.

  Next, the manufacturing method of the coating liquid for transparent conductive layer formation used by this invention is demonstrated. First, the conductive oxide fine particles are mixed with a solvent and, if necessary, a dispersant, and then dispersed to obtain a conductive oxide fine particle dispersion. Examples of the dispersant include various coupling agents such as a silicon coupling agent, various polymer dispersants, and various surfactants such as anionic, nonionic, and cationic types. These dispersants can be appropriately selected according to the type of conductive oxide fine particles used and the dispersion treatment method. Even if no dispersant is used, a good dispersion state may be obtained depending on the combination of the conductive oxide fine particles and the solvent to be applied and the dispersion method. Since the use of a dispersant may deteriorate the resistance and weather resistance of the film, a coating liquid for forming a transparent conductive layer that does not use a dispersant is most preferable. As the dispersion treatment, general-purpose methods such as ultrasonic treatment, homogenizer, paint shaker, and bead mill can be applied.

  By adding a binder component to the obtained conductive oxide fine particle dispersion, and further adjusting the components such as the concentration of the conductive oxide fine particles and the solvent composition, a coating liquid for forming a transparent conductive layer can be obtained. Here, the binder component is added to the dispersion of the conductive oxide fine particles, but it may be added in advance before the above-described dispersion step of the conductive oxide fine particles, and there is no particular limitation. What is necessary is just to set an electroconductive oxide fine particle density | concentration suitably according to the coating method to be used.

  There is no restriction | limiting in particular as a solvent used for the coating liquid for transparent conductive layer formation used by this invention, According to the coating method, film forming conditions, and the material of a base film, it can select suitably. For example, water, methanol (MA), ethanol (EA), 1-propanol (NPA), isopropanol (IPA), butanol, pentanol, benzyl alcohol, diacetone alcohol (DAA) and other alcohol solvents, acetone, methyl ethyl ketone ( MEK), methyl propyl ketone, methyl isobutyl ketone (MIBK), ketone solvents such as cyclohexanone and isophorone, ester solvents such as ethyl acetate, butyl acetate and methyl lactate, ethylene glycol monomethyl ether (MCS), ethylene glycol monoethyl ether (ECS), ethylene glycol isopropyl ether (IPC), propylene glycol methyl ether (PGM), propylene glycol ethyl ether (PE), propylene glycol methyl -Teracetate (PGM-AC), propylene glycol ethyl ether acetate (PE-AC), diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether, Diethylene glycol diethyl ether, diethylene glycol dibutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, glycol derivatives such as dipropylene glycol monobutyl ether, toluene, xylene, mesitylene, dodecyl Benzene derivatives such as benzene, formamide (FA), N-methylformamide, dimethylformamide (DMF), dimethylacetamide, dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, ethylene glycol , Diethylene glycol, tetrahydrofuran (THF), chloroform and the like, but are not limited thereto.

Next, the manufacturing method of the flexible dispersion type EL element of the present invention is explained.
On the base film of the film with a transparent conductive layer, the transparent conductive layer of the base film is lined with a support film, the above-mentioned paste for forming a transparent electrode layer mainly composed of acicular conductive oxide fine particles and a binder or polyethylene dioxy Apply paste for forming transparent electrode layer mainly composed of conductive polymer such as thiophene / polystyrene sulfonic acid (PEDOT / PSS) by screen printing, blade coating, wire bar coating, spray coating, roll coating, gravure printing, etc. After drying, a treatment such as heat treatment (dry curing, heat curing), ultraviolet irradiation treatment (ultraviolet curing) or the like is performed depending on the type of the coating solution to form a transparent electrode layer. The transparent electrode layer may be full surface printing (solid) or pattern printing.

  A method of forming a phosphor layer, a dielectric layer, and a back electrode layer on the transparent electrode layer by sequential screen printing or the like is generally used. Usually, each layer of the phosphor layer, the dielectric layer, and the back electrode layer The coating (printing) forming paste is sequentially applied (printed), dried and heat-cured (usually 120 to 130 ° C.). As these pastes, commercially available pastes can be used. The phosphor layer paste and the dielectric layer paste each contain phosphor particles (zinc sulfide-based fine particles), dielectric fine particles (barium titanate-based fine particles), and a binder whose main component is a high dielectric component such as fluororubber. The back electrode layer paste is dispersed in a solvent, and conductive fine particles such as carbon fine particles are dispersed in a solvent containing a thermosetting resin binder.

  Here, when each layer such as a phosphor layer is screen-printed on the transparent electrode layer, generally, a method is used in which a suction stage having a large number of small-diameter holes is used and the holes are decompressed to fix the film. It is done. If the base film is thin, the film in the hole portion is deformed by the reduced pressure, resulting in a dent, and the problem arises that the dent marks appear on the screen-printed film. Since a support film having sufficient strength is sometimes used and peeled off after the dispersion type EL element is formed, the above problem can be prevented.

  In addition, the transparent electrode layer, the phosphor layer, the dielectric layer, and the back electrode layer constitute the main part of the dispersion-type EL element. In an actual dispersion-type EL element, the collector electrode (silver) Further, an insulating protective coating (formed with an insulating paste) for preventing a lead electrode (formed with a silver paste) of the back electrode layer, a short-circuit between electrodes, an electric shock, and the like are further formed.

The flexible dispersive EL element according to the present invention is excellent in flexibility of the dispersive EL element because the thickness of the base film is thin and flexible, and is a key for devices such as mobile phones, remote controllers, and portable information terminals. It can be applied as a light emitting device incorporated in an input component, and further, a transparent conductive layer is formed on the outer surface of the light emitting surface side of the dispersion type EL device (the surface on the side where the support film of the base film is lined). Therefore, it is possible to effectively prevent the above-mentioned destruction / failure of the device parts due to static electricity.
[Example]

  Examples of the present invention will be specifically described below, but the present invention is not limited to these examples. Further, “%” in the text indicates “% by weight”, and “part” indicates “part by weight”.

  Dispersion treatment is performed by mixing 36 g of granular ITO fine particles (trade name: SUFP-HX, manufactured by Sumitomo Metal Mining Co., Ltd.) with an average particle size of 0.03 μm with 24 g of methyl isobutyl ketone (MIBK) as a solvent and 36 g of cyclohexanone. After that, 3.8 g of urethane acrylate UV curable resin binder and 0.2 g of photoinitiator (Darocur 1173) were added and stirred well to form a transparent conductive layer coating in which ITO fine particles having an average dispersed particle size of 130 nm were dispersed. A liquid was obtained.

After applying corona discharge treatment as an easy-adhesion treatment to one surface of a PET film (made by Teijin Ltd., thickness 25 μm) as a base film, the above-mentioned coating liquid for forming a transparent conductive layer is wired on the treated surface. Bar coating (wire diameter: 0.075 mm), drying at 60 ° C. for 1 minute, and rolling with a hard chromium-plated steel roll having a diameter of 100 mm (linear pressure: 200 kgf / cm = 196 N / mm, nip width: 0. 8 mm), and further, the binder component is cured with a high-pressure mercury lamp (in nitrogen, 100 mW / cm ² × 2 seconds), and a transparent conductive layer composed of ITO fine particles and a binder closely packed on a PET film (Film thickness: 0.5 μm) was formed.
The surface of the base film on which the transparent conductive layer is formed is backed with a support film (PET: 100 μm) having a heat-resistant silicone slightly adhesive layer, and the base film backed with the support film is 150 ° C. × 20 in the atmosphere. The film with a transparent conductive layer according to Example 1 consisting of support film / transparent conductive layer / base film was obtained. The packing density of the conductive fine particles in the transparent conductive layer after the rolling treatment was about 57 vol%. The heat treatment of the base film backed by the support film is performed to prevent shrinkage (size change) and curl of the film due to the heat treatment in the dispersion type EL element manufacturing process described later.
The peel strength between the support film and the transparent conductive layer of the film with a transparent conductive layer was 2.4 g / cm. Here, the above-mentioned peel strength is T-type peel strength (T-type peel is applied to the base film at a tensile speed of 300 mm / min).
Moreover, the dimensional change rate (thermal shrinkage rate) at the time of the heating of the said film with a transparent conductive layer was 0.05%. Here, the dimensional change rate (heat shrinkage rate) was determined by subjecting the film with a transparent conductive layer according to Example 1 to heat treatment (150 ° C. × 30 minutes), and the longitudinal direction (MD) and lateral direction (TD) of the film. ) Shows the dimensional change rate in the vertical direction (MD) having a large value.

  The film characteristics of the transparent conductive layer were visible light transmittance: 95.3%, haze value: 2.0%, and surface resistance value: 1550Ω / □. Note that the surface resistance value is measured one day after the formation of the transparent conductive layer because it tends to temporarily decrease immediately after curing due to the influence of ultraviolet irradiation during binder curing. In addition, although the resistance value of the transparent conductive layer formed on the base film did not change before and after the heat treatment performed after the backing of the support film, this was not supported by the support covering the surface of the transparent conductive layer. It is thought that the slightly adhesive layer of the film acted as a protective layer.

Here, the transmittance | permeability and haze value of the above-mentioned transparent conductive layer are values only of a transparent conductive layer, and are calculated | required by the following formulas 1 and 2, respectively.
[Calculation Formula 1]
Transmittance (%) of transparent conductive layer = [(transmittance measured with transparent conductive layer and base film) / transmittance of base film] × 100
[Calculation Formula 2]
Haze value of transparent conductive layer (%) = (Haze value measured with transparent conductive layer and base film) − (Haze value of base film)

  The surface resistance of the transparent conductive layer was measured using a surface resistance meter Loresta AP (MCP-T400) manufactured by Mitsubishi Chemical Corporation. The haze value and visible light transmittance were measured using a haze meter (HR-200) manufactured by Murakami Color Research Laboratory.

  Next, the base film surface of the film with the transparent conductive layer is subjected to a corona discharge treatment as an easy adhesion treatment, and then the needle-like ITO fine particles are dispersed in the resin binder solution on the treatment surface. SC-120 (manufactured by Sumitomo Metal Mining Co., Ltd.) was screen printed to a size of 4.5 × 5 cm using a 200 mesh polyester screen and dried at 120 ° C. for 30 minutes to form a transparent electrode layer. .

  Further, a phosphor paste (Dupont, 7154J) in which zinc sulfide particles as a phosphor are dispersed in a resin solution containing a fluoropolymer as a main component on the transparent electrode layer, using a 200 mesh polyester screen, is used. A screen was printed to a size of 5 cm and dried at 120 ° C. for 30 minutes to form a phosphor layer.

  A dielectric paste (made by DuPont, 7153) in which barium titanate particles are dispersed in a resin solution containing a fluoropolymer as a main component on the phosphor layer is 4 × 5 cm in size using a 200 mesh polyester screen. This was screen-printed and dried (120 ° C. × 30 minutes), and this was repeated twice to form a dielectric layer.

  A carbon conductive paste (FEC-198, manufactured by Fujikura Kasei Co., Ltd.) is screen-printed to a size of 3.5 × 4.5 cm using a 200 mesh polyester screen on the dielectric layer, dried at 130 ° C. for 30 minutes, and back electrode layer Formed.

  A voltage application Ag lead wire is formed on one end of the transparent electrode layer and the back electrode layer using a silver conductive paste, and the support film is peeled off. / Base film / transparent electrode layer / phosphor layer / dielectric layer / back electrode layer). In order to prevent short-circuit between electrodes, electric shock, etc., an insulating layer is formed using an insulating paste (XB-101G manufactured by Fujikura Kasei Co., Ltd.) as an insulating protective coating for the transparent electrode layer and the back electrode layer as necessary. However, since it is not a part related to the essence of the present invention, details are omitted.

In the production process of the flexible dispersion-type EL element, the support film having the slightly adhesive layer was easily peeled off at the interface between the slightly adhesive layer and the transparent conductive layer. The peel strength between the support film and the transparent conductive layer was 2.3 g / cm. When a voltage of 100 V and 400 Hz was applied between the voltage application lead wires of the flexible dispersion type EL element, the dispersion type EL element emitted light uniformly, and its luminance was measured to be 48 Cd / m ² . The luminance was measured with a luminance meter (trade name: BM-9, manufactured by Topcon Corporation).

In Example 1, a PET film having a thickness of 16 μm was used as a base film, and a transparent conductive layer (film thickness: 0.5 μm) composed of ITO fine particles and a binder closely packed on the PET film was formed. . The packing density of the conductive fine particles in the transparent conductive layer after the rolling treatment was about 57 vol%.
The transparent conductive layer had a visible light transmittance of 95.2%, a haze value of 1.8%, and a surface resistance value of 1450Ω / □. Except this, it carried out similarly to Example 1, and obtained the film with a transparent conductive layer which concerns on Example 2, and the flexible dispersion type | mold EL element.
The dimensional change rate (thermal shrinkage rate) of the film with a transparent conductive layer was 0.05%.

When a voltage of 100 V and 400 Hz was applied between the voltage application lead wires of the dispersion type EL element, the dispersion type EL element emitted light uniformly, and its luminance was measured to be 48 Cd / m ² .

[Comparative Example 1]
In Example 1, an ITO layer (visible light transmittance: 95.0%, haze value: 0%, formed by sputtering) instead of a transparent conductive layer composed of densely packed ITO fine particles and a binder Comparative example in which the surface of the sputtering ITO layer formed on the base film (PET film having a thickness of 25 μm) was lined with a support film (PET film having a thickness of 100 μm). 1 except that the film with a transparent conductive layer according to No. 1 was used, and the dispersion type EL element according to Comparative Example 1 (sputtering ITO layer / base film / transparent electrode layer / phosphor layer / dielectric) Layer / back electrode layer). The dimensional change rate (thermal shrinkage rate) of the film with a transparent conductive layer was 0.05%.

[Comparative Example 2]
In Example 1, instead of a film with a transparent conductive layer having a transparent conductive layer composed of densely packed ITO fine particles and a binder, a PET film (base film) having a thickness of 125 μm by an ITO transparent conductive layer formed by sputtering Using the commercially available film with sputtering ITO transparent conductive layer (visible light transmittance: 92.0%, haze value: 0%, surface resistance value: 100Ω / □) formed thereon, the ITO transparent conductive layer is formed. The dispersive EL device according to Comparative Example 2 was subjected to the same procedure as in Example 1 except that a non-adhesive surface was subjected to corona discharge treatment as an easy adhesion treatment and then a transparent electrode layer was formed on the treated surface. Sputtered ITO transparent conductive layer / PET film / transparent electrode layer / phosphor layer / dielectric layer / back electrode layer) were obtained. The dimensional change rate (heat shrinkage rate) of the sputtering ITO film was 0.3%.

When a voltage of 100 V and 400 Hz was applied between the voltage application leads of the dispersion type EL elements of Comparative Example 1 and Comparative Example 2, the dispersion type EL element emitted light uniformly, and its luminance was measured to be 47 Cd / m. ² .

In addition, the transmittance | permeability and haze value of the above-mentioned sputtering ITO transparent conductive layer are a value only of an ITO layer, and are calculated | required by the following formulas 1 and 2, respectively.
[Calculation Formula 1]
Transmittance (%) of ITO transparent conductive layer = [(Transmittance measured with base film on which ITO transparent conductive layer is formed) / Transmittance of base film] × 100
[Calculation Formula 2]
Haze value (%) of ITO transparent conductive layer = (Haze value measured with base film on which ITO transparent conductive layer is formed) − (Haze value of base film)

"Evaluation of electrostatic resistance"
In the flexible dispersion EL element according to each example, since the outer surface of the base film that becomes the light emitting surface remains conductive even after the dispersion type EL element is manufactured, generation of static electricity is suppressed when the support film is peeled off. It was confirmed that

"Flexibility evaluation of dispersive EL elements (light emission state and electrostatic resistance)"
The flexible dispersive EL element according to each example (with the support film peeled off) and the dispersive EL element according to each comparative example are placed once on a rod having a diameter of 3 mm so that the light emitting surfaces thereof are inside and outside, respectively. After winding, a voltage of 100 V and 400 Hz was applied between the voltage application leads of the dispersion type EL element, and the light emission state of the element was observed. In each Example and Comparative Example 1, no change was observed in the light emission state. In Comparative Example 2, the PET film as a base material was as thick as 125 μm, or it was difficult to wind around a 3 mm diameter rod. When it was forcibly wound, a peeled part was generated in some elements, resulting in non-uniform light emission.
Regarding the conductivity of the outer surface of the base film serving as the light emitting surface, in each example, there was no significant change before and after the above test, but in each comparative example, the sputtering ITO layer on the outer surface of the base film was cracked. And the conductivity was completely lost.

"Evaluation of keystroke durability of light-emitting EL elements (light emission state and electrostatic resistance)"
The keystroke durability was evaluated using a keystroke tester for the flexible dispersive EL element according to each example (with the support film peeled off) and the dispersive EL element according to each comparative example. Specifically, while applying a voltage of 100 V and 400 Hz between the voltage application leads of the distributed EL element and observing the light emission state of the element, a keystroke test is performed at a load of 300 g and the deterioration of the light emission state is visually observed. And evaluated. In each Example and each Comparative Example, no change was observed in the light emission state even after 2 million keystrokes.
However, in the flexible dispersion EL element according to each example, the outer surface of the base film that becomes the light emitting surface after the keystroke of 2 million times had conductivity, whereas in Comparative Example 1 and Comparative Example 2, After 1 million keystrokes, the sputtering ITO layer on the outer surface of the base film serving as the light emitting surface was cracked and peeled off, and the conductivity was completely lost.

"Evaluation of click feeling"
The flexible dispersive EL element according to each example and the dispersive EL element according to the comparative example were affixed on a dome contact switch for a mobile phone, and the click feeling was evaluated. In Examples 1 and 2 and Comparative Example 1, a good click feeling was obtained, but in Comparative Example 2, a sufficient click feeling was not obtained.

It is sectional drawing which shows the basic structure of the conventional dispersion-type EL element. It is sectional drawing which shows another structure of the conventional dispersion-type EL element. It is sectional drawing which shows the state by which the flexible dispersion type EL element which concerns on this invention was backed by the support film. It is sectional drawing which shows the flexible dispersion type | mold EL element which concerns on this invention. It is sectional drawing which shows the flexible dispersion type | mold EL element which concerns on this invention, and shows the state which peeled and removed the support film which has a slightly adhesive layer from the state of FIG. 4 in the interface of a base film and a slightly adhesive layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent plastic film 2 Transparent electrode layer 3 Phosphor layer 4 Dielectric layer 5 Back electrode layer 6 Current collection electrode 7 Insulation protective layer 8 Transparent conductive layer 9 Base film 10 Support film

Claims (11)

A film with a transparent conductive layer in which a transparent conductive layer is formed on a base film by a coating method, and a thin adhesive layer that can be peeled off at the interface with the transparent conductive layer on the transparent conductive layer side of the film with a transparent conductive layer The base film has a thickness of 3 to 25 μm, and the transparent conductive layer is mainly composed of conductive oxide fine particles and a binder matrix, and is subjected to a compression treatment. A film with a transparent conductive layer.   The peel strength between the slightly adhesive layer and the transparent conductive layer (the force required for peeling per unit length in the peeled portion) is 1 to 15 g / cm regardless of the presence or absence of the heat treatment step. The film with a transparent conductive layer according to claim 1.   3. The film with a transparent conductive layer according to claim 1, wherein the dimensional change rate (heat shrinkage rate) in the vertical direction and the horizontal direction of the film with the transparent conductive layer is both 0.3% or less.   The thickness of the said base film is 3-9 micrometers, The film with a transparent conductive layer of any one of Claims 1-3 characterized by the above-mentioned.   5. The transparent conductive material according to claim 1, wherein the conductive oxide fine particles contain at least one of indium oxide, tin oxide, and zinc oxide as a main component. Layered film.   The film with a transparent conductive layer according to any one of claims 1 to 5, wherein the conductive oxide fine particles containing indium oxide as a main component are indium tin oxide fine particles.   The film with a transparent conductive layer according to claim 1, wherein the binder matrix is cross-linked and has resistance to an organic solvent.   The film with a transparent conductive layer according to claim 1, wherein the compression treatment is performed by rolling a metal roll.   After forming at least a transparent electrode layer, a fluorescent substance layer, a dielectric material layer, and a back electrode layer in order on the surface in which the transparent conductive layer of the film with a transparent conductive layer according to claim 1 is not formed, the fine adhesion A flexible dispersive electroluminescent element, wherein a support film having a layer is peeled and removed at an interface between a transparent conductive layer and a slightly adhesive layer formed on the base film.   An electronic device, wherein the flexible dispersive electroluminescence element is applied as a light emitting element incorporated in a key input component of the device.   The electronic device according to claim 10, wherein the electronic device is a mobile phone, a remote controller, or a portable information terminal.