JP2005305674A - Gravure printing plate and printing equipment employing the same and manufacturing method of organic el element by employing gravure printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gravure printing plate, with which a highly minute pattern can be printed without bruising a board such as a glass board even under the condition that a structure with a metal plate suitable for printing the highly minute pattern is employed. <P>SOLUTION: This gravure printing plate is made of a pattern image area 2 consisting of ink receiving parts grooved so as to square with an aimed pattern formed on the outer peripheral part of a metal plate main body 1 and resin buffer layers 3 abutting against the board at the pressing of the plate main body to the board formed on the portion except the pattern image area of the outer peripheral part of the plate main body. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique suitably applied to printing an ink pattern that matches a target pattern on a substrate that is easily damaged, such as a glass substrate or a PET (polyethylene terephthalate) substrate.

Research and development of lightweight, high-efficiency flat panel displays for computer information display or television screen display is underway. A cathode ray tube (CRT) that has been widely used as a display that has been mainly used in the past is a cathode ray tube (CRT) that has excellent luminance and color reproducibility. As panel displays, liquid crystal panel displays or plasma panel displays have been commercialized, and some products are being replaced.
However, the liquid crystal panel display has a problem that the viewing angle is narrow and the responsiveness to high-speed pixel signals is not sufficient, and the plasma panel display consumes a large amount of power. There is a problem.

Recently, an organic electroluminescent element (organic EL element) using an organic light emitting material has been attracting attention. By using an organic compound as a light emitting material, the response speed is high even if it is self-luminous. In addition, it is expected to be able to realize a low power consumption flat panel display having no viewing angle dependency.
FIG. 5 shows an example of the structure of this type of organic electroluminescent device. The EL device 100 of this example is a transparent pixel electrode (anode) made of ITO (indium tin oxide) on a transparent glass substrate 101. 102, a hole transport layer 103, a light emitting layer 104, an electron transport layer 105, and a metal cathode 106 are sequentially formed by, for example, a vacuum deposition method.

In the EL element 100 having this configuration, when a DC voltage is applied between the anode pixel electrode 102 and the cathode 106 from the DC power source 107, holes as holes injected from the pixel electrode 102 become holes (holes). The electron-hole pairs recombine in the light-emitting layer 104, and light emission 108 having a predetermined wavelength is generated therefrom. This can be observed from the outside of the transparent glass substrate 101.
As another example of the specific layer structure of the EL element 100 described above, as shown in FIG. 6, the material of the hole transport layer 103 is poly (3,4) -ethylenedioxythiophene (hereinafter abbreviated as PEDOT). And poly (2-methoxy-5- (2′-ethylhexyloxy) -1,4-phenylenevinylene) (hereinafter abbreviated as MEH-PPV) and electrons as a layer that serves both as an electron transport layer and a light-emitting layer. A structure is also known in which a transporting light emitting layer 110 is used, and a cathode 106 made of an aluminum electrode layer and a calcium (Ca) layer 111 that enhances electron injection properties is provided thereon.

Next, FIG. 7 shows a structural example in which the EL element having the basic structure shown in FIG. 5 or 6 is applied to a flat display device.
As shown in the drawing, an organic laminated structure composed of an electron transport layer 115 and a hole transport layer 116 is disposed between the cathode 117 and the anode 118 in a predetermined pattern. The cathode 117 and the anode 118 are provided in stripes crossing each other, and are selected by the luminance signal circuit 120 and the control circuit 121 with a built-in shift register, respectively, and applied with a signal voltage. Thus, the EL element portions existing at the positions (pixels) where the selected cathode 117 and anode 118 intersect each other are configured to emit light individually.

From such a background, a method for producing a device using a polymer EL material has attracted attention, and one of them is a method for producing a polymer device by an ink jet printing technique. (See Patent Document 1 and Patent Document 2)
The technique described in Patent Document 1 has a problem that only a material having a low viscosity can be used, and since it is a droplet discharge type, a pattern cannot be formed unless an enclosure is provided with a black resist. Further, according to the technique described in Patent Document 2, since the ink material can only be used if it is water-soluble, and it is desirable that the ink material be soluble in the solvent, only a limited solvent can be used. Since it is a droplet jetting method, there is a problem that it is disadvantageous for manufacturing a large area.
From such a background, a method for producing an EL element by printing an EL material on a substrate using a printing technique has attracted attention. (See Patent Document 3)
JP-A-10-153967 JP-A-10-153967 JP 2003-17248 A

In the technology described in the above-mentioned Patent Document 3, in an EL element in which a layer having a light emitting region is provided between a first electrode and a second electrode, at least one of the plurality of layers is relief printing. The present invention relates to a method of forming a predetermined pattern by transfer using a reverse offset method.
This method has an advantage that a large-area layer can be formed with high accuracy at high speed by a transfer printing technique using a roll in which ink is formed in a necessary pattern on the outer peripheral portion.
Therefore, in this type of printing method, when a layer necessary for EL element formation is formed on a glass substrate with a necessary pattern using a gravure printing plate, the substrate for the EL element is a glass substrate, which is hard and brittle. Therefore, when the transfer roll is pressed against the glass substrate, the transfer roll rubs against the surface of the glass substrate, which may damage the surface of the glass substrate. Particularly in the case of forming a high-definition pattern such as an EL element, the gravure printing plate is a metal plate having high pattern formation accuracy and small distortion of the pattern shape. There is a high risk of damaging the surface of the substrate. In addition, in view of this point, when trying to apply a resin printing plate, the resin printing plate has a low solvent resistance with respect to toluene, xylene, etc., which are frequently used as constituent materials for EL elements, and the solvent resin plate There was a problem that the pattern was distorted by the impregnation of the ink and was not suitable for high-definition printing.

  In order to solve the above problems, the present inventors have ensured a high-definition pattern without damaging a substrate such as a glass substrate or a PET substrate even in a structure using a metal plate suitable for high-definition pattern printing. An object of the present invention is to provide a gravure printing plate and apparatus capable of printing on the surface and an EL element manufacturing method using the previous gravure printing plate.

In order to achieve the above object, the present invention employs the following configuration.
In the present invention, a printing metal plate for forming a pattern made of ink on a substrate such as a glass substrate by high-definition printing, the target pattern on the surface of the plate body made of metal A pattern image line portion composed of a concave ink receiving portion is formed so as to match, and a portion of the surface of the plate body excluding the pattern image line portion is applied to the substrate during ink transfer by pressing the plate body against the substrate. It is characterized in that a resin-made buffer layer is formed.
In the present invention, the buffer layer is preferably made of a resin that repels ink.
In the present invention, the resin that repels the ink is preferably composed of any one of a silicone-based resin, a fluororesin, a butyl rubber, a urethane rubber, an acrylonitrile rubber, a polyvinyl chloride, and a polycarbonate resin.
In the present invention, it is preferable to expose a layer that does not repel ink in the pattern image area.
In the present invention, the layer that does not repel the ink is preferably a butyl rubber or ethylene propylene rubber layer.
In the present invention, it is preferable that the ink is an ink formed from a polymer organic light emitting material for producing an organic EL element.
A gravure printing apparatus according to the present invention includes any one of the above gravure printing plates.

The method for producing an EL device according to the present invention is a method for producing an organic EL device on a substrate such as a glass substrate by high-definition printing an ink pattern made of a polymer organic light emitting material into an organic material. A method for forming an EL element, wherein a pattern image line portion comprising a concave ink receiving portion is formed on a surface portion of a plate body made of metal so as to match a target pattern, and the surface of the plate body A gravure printing plate in which a resin buffer layer that contacts the substrate at the time of ink transfer by pressing the plate main body against the substrate is formed in a portion other than the pattern image drawing portion of the portion, and the pattern image drawing portion is high. It contains a molecular organic light emitting material in ink form, and this gravure printing plate is pressed onto a substrate to print an ink pattern corresponding to the pattern image portion on the substrate. That.
The EL device manufacturing method according to the present invention is characterized in that a resin repelling ink is used for the buffer layer.
The method for producing an EL device according to the present invention comprises exposing a layer that does not repel ink in the pattern image portion, and printing the ink pattern by transferring the ink contained in the pattern image portion onto the substrate. Features.

In the printing plate according to the present invention, high-definition printing of a target pattern can be performed by transferring the ink in the pattern image portion of the plate body onto a substrate such as a glass substrate. Further, when transferring the ink of the pattern image portion, even if the resin buffer layer provided on the portion excluding the pattern image portion of the metal plate is pressed against the substrate surface such as a glass substrate, the glass substrate or There is little risk of scratching the surface portion of a substrate such as a PET substrate.
Furthermore, since the pattern image area itself is formed on the metal plate part, the shape will not be deformed or distorted even when subjected to immersion in a solvent, etc., and high-definition pattern printing can be reliably obtained. Can do. Therefore, even if the printing object is a layer of organic EL material formed on the glass substrate of the EL element, and various solvents for the material layer touch the plate body, the pattern image area itself is distorted by the solvent. Therefore, high-definition pattern printing can be performed.
Of course, compared with a printing method using a droplet jetting method such as an ink jet method, the present invention can cope with printing at a high speed and a large area, and there is no restriction such as a material having a low viscosity, and there is a restriction that it is a water-soluble ink. Therefore, it is possible to provide a technology with high versatility of the solvent and high versatility of the ink.

If the buffer layer provided outside the pattern image area is made of a resin that repels ink, even if the ink leaks out from the ink receiving area of the pattern image area, the buffer layer repels the ink, so it is unnecessary for the buffer layer. Ink becomes difficult to adhere. As a result, it is difficult for unnecessary ink stains to adhere to the buffer layer, the print surface is difficult to stain, and background stains and the like do not occur.
The ink receiving part of the pattern line part does not repel the ink and exposes a layer that is well-adhered to the ink, so that the ink on the pattern line part is good and the print pattern is clear and has a good cut A beautiful pattern printing surface can be obtained.
The polymer gravure printing plate of the present invention is particularly effective as long as it is a polymer organic EL light-emitting material for creating an EL element as an ink to be used, and a good printing surface having the various features described above is formed on a substrate. can do.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
1 to 3 are for explaining a process for producing a gravure printing plate according to the present invention, and the structure shown in FIG. 3 is a gravure printing plate A according to the present invention.
The gravure printing plate A in this form includes a drum-shaped plate body 1 made of a metal material rich in corrosion resistance such as stainless steel, and a plurality of concave pattern image-drawing portions 2 formed on the outer periphery of the plate body 1. The outer peripheral portion (surface portion) of the plate body 1 is configured to include a resin-made buffer layer 3 attached to a portion excluding these pattern image portions 2.
Since the surface of the plate body 1 is required to have high corrosion resistance against solvents such as toluene and xylene, which are solvents for organic EL materials applied to EL elements, etc., stainless steel, copper, chromium having high corrosion resistance are required. It is preferable to be made of a metal material such as steel, but even if the whole is not made of a single material such as stainless steel, only the outer periphery that touches the solvent is made of a metal material rich in corrosion resistance, and the inner side is made of another metal material. You may form from.

  The pattern image portion 2 can take an appropriate shape in accordance with an intended electrode pattern, wiring pattern, or EL element arrangement pattern to be formed. For example, in order to stack the EL material layer on the glass substrate in a stripe shape so as to match the shape of the stripe electrode (cathode 117 and anode 118) having the EL element structure shown in FIG. It is only necessary to form a plurality of linear grooves having a required length along the length direction or the circumferential direction at regular intervals. These pattern image line portions 2 are recessed ink receiving portions, and ink is supplied to these pattern image line portions 2 from an ink supply device such as a plate cylinder (not shown). If these pattern image portions 2 are for EL elements having the structure shown in FIG. 7 and the like, they are formed at a predetermined pitch with a high definition with a width of about several tens μm to several hundreds μm.

The buffer layer 3 has a thickness of about 1 to 20 μm, more preferably a thickness of about 10 to 20 μm, and is made of a softer resin than the metal material constituting the plate body 1. If the thickness of the buffer layer 3 is too thin, there is a high risk of damaging a substrate that is easily damaged such as a glass substrate. Conversely, if it is too thick, there is a possibility that the transfer of ink may be hindered.
As the resin constituting the buffer layer 3, nitrile rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, butyl rubber, acrylonitrile rubber, ethylene propylene rubber, silicone resin, fluorine resin, polyethylene resin, polyvinyl chloride resin, pre-polymer Styrene resin, urethane resin, polycarbonate resin, epoxy resin, polyolefin resin, polyimide resin, siloxane elastomer, fluorine elastomer, etc. can be used. Among these, silicone resin, fluorine resin, butyl rubber, urethane rubber, acrylonitrile It is preferably made of any one of rubber, polyvinyl chloride, and polycarbonate resin. Among these, fluororesin, butyl rubber, urethane rubber, acrylonitrile rubber, polyvinyl chloride, and polycarbonate resin are preferable for application because they are excellent in solvent resistance.
Of these, any of silicone-based resin, fluororesin, butyl rubber, urethane rubber, acrylonitrile rubber, polyvinyl chloride, and polycarbonate resin repels the ink. Repels ink when it tries to leak from the outside and acts so that ink does not come out of the pattern image area 2, so that unnecessary adhesion of ink to the buffer layer 3 side can be suppressed, and the printing surface Is more preferable because it is difficult to stain and does not cause soiling.

In order to manufacture the gravure printing plate A configured as described above, a metal drum 4 made of stainless steel is prepared, and a resin layer 5 having a uniform thickness is formed on the entire outer peripheral surface of the metal drum 4 as shown in FIG. For example, with a thickness of 1 to 20 μm. As a method for forming the resin layer 5, a conventional method known as a method for forming a resin layer on the surface of a target object, such as a dipping method, a wire coating method, or a die coating method, in which the metal drum 4 is dipped in a resin liquid and pulled up is appropriately used. Just choose.
As shown in FIG. 1, after the resin layer 5 is coated on the entire outer peripheral surface, unnecessary portions of the resin layer 5 are removed in accordance with the target pattern to form the holes 5a. For this purpose, a necessary pattern may be directly drawn with a laser from the top of the resin layer 5 and shaved, or a resist is coated using a photolithography technique, and the resist is partially exposed before being developed. It is also possible to perform an etching process so as to remove the part other than the remaining part of the resist and to remove a part of the resin layer 5 as shown in FIG. Among these methods, the method of drawing with a laser can reduce the number of steps, and the hole 5a having a free size can be easily formed.

When the hole 5a of the resin layer 5 is formed as shown in FIG. 2, the resin layer 5 is used as a mask to remove a necessary portion of the outer peripheral surface of the metal drum 4 by etching to form a recess. The gravure printing plate A provided with the plate body 1 can be obtained by forming the pattern image portion 2 shown in FIG.
The etching of the metal drum 4 here is different depending on the type of metal, but using an acidic etching solution is simple and the cost can be reduced. In addition, when forming the very fine micron-order pattern image drawing portion 2, a dry etching method can be used. In this case, in order not to damage the resin layer 5, the resin layer 5 is patterned by a photolithography method. It is only necessary to apply and dry-treat the metal drum 4 along the hole 5a after forming the hole 5a.
Through these steps, the gravure printing plate A having the structure shown in FIG. 3 can be obtained.

In order to perform printing using the gravure printing plate A having the above-described structure, the necessary ink is supplied to the pattern image portion 2 which is an ink receiving portion of the plate body 1.
In this embodiment, a case where an EL element is formed on a transparent substrate such as a glass substrate or a PET (polyethylene terephthalate) substrate will be described as an example.
As an organic material for producing an EL element, an organic light emitting material (for example, a polymer light emitting material such as MEH-PPV, a low molecular light emitting material such as anthracene or phthalocyanine) or a precursor thereof is water or an organic solvent (for example, cyclohexanone, tetrahydrofuran (THF). ), Xylene, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile, etc.) The gravure printing plate A provided with the ink on the pattern image area 2 of the plate body 1 is prepared on the previous substrate. The light emitting layer can be formed by pressing the ink while rotating it up and transferring the ink along the desired pattern onto the substrate.

Examples of other inks include a polymer light emitting material such as MEH-PPV or a precursor thereof and an organic material such as PEDOT or a precursor thereof in water or an organic solvent (for example, cyclohexanone, tetrahydrofuran (THF), xylene, dimethylformamide). (DMF), dimethyl sulfoxide (DMSO), acetonitrile, etc.), each of which is prepared by dissolving or dispersing the prepared ink, and transferring the composite layer (laminated structure) of the polymer light emitting material and the organic material to the previous substrate. It can also be formed on top.
In addition, an electron transporting light emitting layer may be formed on the hole transport layer by transferring a predetermined pattern of the ink, or a single color layer or a multicolor layer may be formed by transferring the predetermined pattern of ink.
Further, for example, an electrode patterned at least for each pixel is formed on a substrate such as glass, and the layer is formed in a predetermined pattern thereon, or an electrode patterned at least for each pixel is formed on a substrate such as glass. On top of that, at least three kinds of light emission colors of red, green and blue can be transferred for each color to form the light emission layer of each color in a predetermined pattern.

FIG. 4 shows a state in which a part of the EL element is manufactured using the gravure printing plate A having the above-described configuration.
In this example, a plurality of ITO strip-like transparent pixel electrodes 21 are formed on a glass substrate 20 by patterning by vacuum deposition and photolithography, and PEDOT for forming a hole transport layer is formed on the transparent pixel electrodes 21. A solution such as MEH-PPV described above using a gravure printing plate A as shown in FIG. If the ink layer K such as a material is subjected to gravure printing and the ink layer K is heated to remove the solvent, a striped light emitting layer is completed.
In the gravure printing plate A, the buffer layer 3 is in contact with the upper surface of the hole transport layer 23 or is not shown, but in the region where the transparent pixel electrode 21 and the hole transport layer 23 are not formed on the upper surface of the substrate 20. Since the gravure printing plate A rotates while being in contact with the upper surface of the ink and the ink layer K accommodated in the pattern image portion 2 is transferred, the cushioning action is provided by the presence of the buffer layer 3 and the upper surface of the substrate 20 is Hard to get scratched. Accordingly, the organic EL element can be manufactured without damaging the upper surface of the substrate 20.
In addition, if the previous ink layer K produced using the gravure printing plate A is heated and dried to form a plurality of stripe-shaped light emitting layers, a calcium layer or an electrode layer is formed thereon by vacuum deposition and patterning. By forming the organic EL element, it is possible to manufacture the organic EL element having the basic laminated structure described above based on FIG. 6 and the pixel structure described above based on FIG.

By the way, a layer familiar to ink that does not repel ink may be applied and formed on the inner surface side of the pattern image portion 2 of the plate body 1 described above. The layer that does not repel these inks is, for example, a butyl rubber or ethylene propylene rubber layer.
By forming these layers on the inner surface of the pattern image portion 2, the ink can be satisfactorily applied to the pattern image portion 2 and the printing finish can be improved.

The gravure printing apparatus according to the present invention includes the above-described gravure printing plate A, and includes an ink supply device and a substrate transport device. The ink supply device and the substrate transport device may be those commonly used in general gravure devices.
Since the gravure printing apparatus having this configuration includes the gravure printing plate A having the previous configuration, various effects obtained by using the previous gravure printing plate A can be obtained.

A resin having a thickness of 10 to 20 μm made of silicon resin (manufactured by Toshiba GE Silicone Co., Ltd.) is applied and formed on the outer peripheral surface of a metal drum made of stainless steel having a diameter of 100 mm, and the silicon resin is patterned by using a laser plate making machine. Next, this stainless steel layer is engraved in a pattern shape (pattern dimension: L / S = 200 μm / 80 μm) using 2N hydrochloric acid to form a pattern image portion, and ink (MEH-PPV) is formed on the pattern image portion. , 0.8%, anisole solution) to form a gravure printing plate.
This gravure printing plate was attached to a gravure proofing machine and printed on a PET (polyethylene terephthalate) film. At that time, the pressing force of the gravure printing plate was 30 kg / m, the moving speed of the PET film was 0.8 m / sec, and the gravure printing plate was rotated in synchronization with the movement of the PET film.

With this gravure printing plate, it was possible to print a high-definition pattern of 200 μm ± 10 μm on the upper surface of the PET film without scratching the PET film surface.
On the other hand, when the same pattern image line part was formed using a gravure printing plate in which the resin layer was not coated on the outer peripheral surface of the plate body, and printing was performed using this plate, the substrate had streaks. I got a wound.
In addition, a gravure printing plate in which the entire plate body is made of urethane resin was also prototyped and used for testing. However, the printing of a high-definition pattern of 200 μm ± 10 μm was hindered and the pattern was distorted.
Furthermore, in the above example, when the thickness of the silicon resin was 0.8 μm, and the gravure printing plate was manufactured under the same conditions, and subjected to printing, the silicon resin was too thin and the PET film was slightly scratched. . Moreover, when the thickness of the silicon resin was 23 μm, and the gravure printing plate was manufactured under the same conditions as other conditions, and subjected to printing, the silicon resin swelled and protruded to the concave pattern image line side, and was 200 μm ± 10 μm. The high-definition pattern printing edge portion was not linear, and irregularities of about 25 μm were produced. Accordingly, when the gravure printing plate is used for this purpose, the thickness of the buffer layer seems to be advantageous in the range of 1 to 20 μm.

FIG. 1 is a view showing a state in which a resin layer is coated on the outer periphery of a metal drum. FIG. 2 is a view showing a state in which holes are formed in the resin layer on the outer periphery of the metal drum. FIG. 3 is a diagram showing a gravure printing plate in which a pattern image line portion is formed on the outer periphery of a metal drum. FIG. 4 is a cross-sectional view showing a state in which a part of the EL element is manufactured using the gravure printing plate according to the present invention. FIG. 5 is a cross-sectional view showing one structural example of an EL element. FIG. 6 is a cross-sectional view showing another structural example of the EL element. FIG. 7 is a configuration diagram illustrating an example of a display device using an EL element.

Explanation of symbols

  A ... gravure printing plate, 1 ... plate body, 2 ... pattern image area, 3 ... buffer layer, 4 ... metal drum, 5 ... resin layer, 5a ... hole, K ... ink layer.

Claims (10)

  A printing metal plate for forming a pattern made of ink on a substrate such as a glass substrate by high-definition printing, and having a concave shape so as to match the target pattern on the surface of the plate body made of metal A resin-made buffer layer formed with a pattern image portion comprising an ink receiving portion and abutting against the substrate during ink transfer by pressing the plate body against the substrate at a portion other than the pattern image portion on the surface portion of the plate body A gravure printing plate characterized in that is formed.   The gravure printing plate according to claim 1, wherein the buffer layer is made of a resin that repels ink.   The gravure printing plate according to claim 2, wherein the resin that repels the ink is made of any one of a silicone-based resin, a fluororesin, a butyl rubber, a urethane rubber, an acrylonitrile rubber, a polyvinyl chloride, and a polycarbonate resin.   The gravure printing plate according to any one of claims 1 to 3, wherein a layer that does not repel ink is exposed in the pattern image portion.   The gravure printing plate according to claim 4, wherein the layer that does not repel the ink is a butyl rubber or ethylene propylene rubber layer.   The gravure printing plate according to any one of claims 1 to 5, wherein the ink is an ink made of a polymer organic light emitting material for producing an organic EL element.   A gravure printing apparatus comprising the gravure printing plate according to claim 1. A method for forming an organic EL element on a substrate such as a glass substrate by high-definition printing an ink pattern made of a polymer organic light emitting material in ink form. ,
A pattern image line portion comprising a concave ink receiving portion is formed on the surface portion of the plate body made of metal so as to match a target pattern, and the substrate is not formed on the surface portion of the plate body excluding the pattern image line portion. A gravure printing plate in which a resin buffer layer that contacts the substrate at the time of ink transfer by pressing the plate main body against the plate is used, and an ink made of a polymer organic light-emitting material is accommodated in the pattern line portion. The method for producing an organic EL element, wherein the gravure printing plate is pressed onto a substrate to print an ink pattern corresponding to the pattern image portion on the substrate.   The method for producing an organic EL element according to claim 8, wherein a resin repelling ink is used for the buffer layer. 10. The ink pattern is printed by exposing a layer that does not repel ink in the pattern image portion, and transferring the ink stored in the pattern image portion onto the substrate. Manufacturing method of organic EL element.

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