JP5315586B2 - Manufacturing method of electronic device using relief printing plate for high definition and organic EL element - Google Patents

Description

  The present invention relates to a relief plate for high-definition printing such as an electronic device such as an organic EL element, and in particular, when performing high-definition printing by a relief printing method using a low-viscosity ink such as an ink for an organic EL element. The present invention relates to a letterpress for obtaining a high-definition printed matter excellent in reproducibility, a method for producing an electronic device using the same, and an organic EL element.

  In recent years, the development of electronic devices using high-definition processing technology has made rapid progress. Such electronic devices are expected to contribute to the development of next-generation electronics, biotechnology, optronics and other fields.

  The organic EL element, which is one of the electronic devices, is one in which an organic light emitting layer made of an organic light emitting material is formed between two opposing electrodes, and light is emitted by passing a current through the organic light emitting layer. In order to emit light, the thickness of the light emitting layer is important, and it is necessary to form a thin film of about 100 nm. Further, in order to make this a display, it is necessary to pattern it with high definition.

  Organic light-emitting materials include low-molecular materials and high-molecular materials. In general, low-molecular materials are formed into thin films by resistance heating vapor deposition or the like, and then patterned using a fine pattern mask. There is a problem that the patterning accuracy is less likely to increase as the size increases.

  Therefore, recently, a method of using a polymer material as an organic light emitting material, dissolving the organic light emitting material in a solvent to form a coating liquid, and forming a thin film by a wet coating method has been tried. As the wet coating method for forming a thin film, there are a spin coating method, a bar coating method, a protruding coating method, a dip coating method, and the like. However, it is considered difficult to form a thin film by a printing method that is good at coating patterning.

  Furthermore, among various printing methods, organic EL elements and displays often use a glass substrate as a substrate, and therefore methods such as gravure printing that use hard plates such as metal printing plates are unsuitable and elastic. An offset printing method using a rubber plate having a stencil and a relief printing method using a photosensitive resin plate mainly composed of rubber or other resin are appropriate. Actually, as a trial of these printing methods, a method by offset printing (for example, see Patent Document 1), a method by letterpress printing (for example, see Patent Document 1), and the like have been proposed.

The above prior art documents are shown below.
JP 2001-93668 A JP 2001-155858 A

It is known that each printing method such as letterpress printing, intaglio printing, and offset printing has an optimum viscosity of the coating liquid, and a viscosity modifier such as a thickener is added to the coating liquid. It is common.

  On the other hand, when an organic light emitting material is formed by a printing method, the organic light emitting material is dispersed or dissolved in water, alcohol, or an organic solvent to form a coating liquid.

  However, a general organic light-emitting material that can be made into a coating liquid has a maximum solid content ratio of about 5% even when the solubility in a solvent is high. It is difficult to increase the viscosity of the working fluid.

  In addition, when an organic light emitting material is formed and driven as an element, the durability of the film formed from the organic light emitting material is preferably higher. The remaining thickener cannot be added, and for this reason, it is difficult to increase the viscosity of the coating liquid.

  As a result, when trying to print the coating liquid of the organic light emitting material by the relief printing method, the coating liquid flows into the concave portion of the relief printing, which is a non-image area, because the coating liquid has a low viscosity. As a result, not only the coating liquid on the convex surface of the relief printing plate that is the image area but also the coating liquid that has flowed into the concave portion is transferred to the substrate when the coating liquid is transferred to the substrate that is the transfer target. As a result, there is a problem that it is difficult to produce printed matter with excellent reproducibility of the image area.

  In particular, when high-definition printing is performed by the relief printing method, the pitch of the convex portions that are the image line portions of the relief plate is narrowed, and at the same time, the depth of the concave portions that are the non-image line portions is shallow. This tendency is seen whether the convex portion, which is the image portion of the convex plate, is formed using a photosensitive resin, or when the metal plate is manufactured by an etching method or the like. Therefore, in the case of performing high-definition printing, when a low-viscosity coating liquid (ink) such as a coating liquid containing an organic light emitting material is used, it is difficult to print with high reproducibility.

  The present invention solves the problems and difficulties of the prior art, and the problem is that when high-definition printing is performed on a hard substrate such as glass by the relief printing method, the relief printing is performed. The depth of the concave portion, which is a non-image area of the relief printing plate used in the method, is increased, and the coating is low in viscosity and dispersed in an aromatic solvent or halogen solvent, such as a coating liquid (ink) for organic EL elements. High-definition relief printing plate capable of obtaining printed matter with excellent reproducibility of the image area even when using a working liquid (ink), a method for producing an electronic device using this relief printing plate, and an organic EL obtained by this production method It is to provide an element.

In order to achieve the above-mentioned problems in the present invention, the invention according to claim 1 is a relief plate for obtaining a high-definition printed matter by transferring ink containing a functional material to a substrate by a relief printing method, The image line portions of the high-definition printed matter are arranged at a constant pitch width, and when the pitch width is a, the convex portions that are image line portions have a pitch width of n × a (n is an integer of 2 or more). The high-definition printing relief plate is characterized by the use of a high-definition printing relief plate that has a rotating cylindrical shape, and the convex portion as the image line portion has a pitch width of n × a in the rotation axis direction. Ink containing a functional material is supplied to the printing relief printing plate, the supplied ink is transferred to a hard base material by a circular pressure method, and the high-definition printing relief printing plate is translated in the rotation axis direction by a width a. Repeat the same ink transfer n times and organic light emission supplemented to the inking device A surplus of the ink for the organic EL element containing the material is removed by a doctor device, which is a method for manufacturing an electronic device.

The invention of claim 2 is an organic EL device obtained by the electronic device manufacturing method of claim 1 .

  Since this invention is the above structure, there exist the following effects.

That is, according to the first aspect of the present invention, a relief printing plate for obtaining a high-definition printed matter by transferring ink containing a functional material to a substrate by a relief printing method, wherein the image area of the high-definition printed matter is High-definition printing characterized by being arranged with a constant pitch width, and assuming that the pitch width is a, the convex portion as the image line portion has a pitch width of n × a (n is an integer of 2 or more). Use a high-definition printing relief plate that has a cylindrical shape that rotates and has an image line portion with a pitch width of n × a in the direction of the rotation axis, and a functional material is applied to the high-definition printing relief plate. Supplying the ink containing, transferring the supplied ink to a hard substrate by a circular pressure method, translating the relief plate for high-definition printing in the rotation axis direction by a width a, and repeating the transfer n times , and out of the ink for an organic EL device including an organic luminescent material supplemented to the inking unit Retained things may be a method for manufacturing an electronic device, and removing a doctor device.

Further , according to the invention according to claim 2, the organic EL element obtained by the method for manufacturing an electronic device according to claim 1 can obtain an organic light emitting layer having excellent reproducibility, and thus sharp. This is to make it possible to obtain a display having an excellent image.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a perspective view and a sectional view of a relief printing plate for high-definition printing according to the present invention. Reference numeral 1 denotes a support constituting the relief printing plate, and reference numeral 2 denotes a projection that is an image portion of the relief printing plate. The support 1 only needs to have mechanical strength against printing, and a known metal, resin, or laminate thereof can be used. Moreover, the convex part 2 which is an image part of a relief plate should just use at least 1 or more types of resin, and may select either a single layer structure or a laminated structure. However, it is necessary that the resin layer be on the surface in contact with the coating solution. Resin materials used in 2 include nitrile rubber, silicone rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, butyl rubber, acrylonitrile rubber, ethylene propylene rubber, urethane rubber, polyethylene, polystyrene, polybutadiene, etc. , Synthetic resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyamide, polyethersulfone, polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyvinyl alcohol, copolymers thereof, natural polymers such as cellulose, etc. One or more types can be selected from the above. However, when applying a coating solution such as an organic light emitting material, from the viewpoint of solvent resistance against organic solvents, fluorine-based elastomers and polytetrafluoroethylenes are used. Water-soluble such as fluorinated resins such as len, polyvinylidene fluoride, poly (vinylidene fluoride) and copolymers thereof, polyamide, polyvinyl alcohol, cellulose acetate succinate, partially saponified polyvinyl acetate, and cationic piperazine-containing polyamide It is desirable to use a solvent soluble.

  FIG. 2A shows a target printed matter, and FIG. 2B shows a high-definition relief printing plate used for producing the printed matter of FIG. 2A in the present invention. Reference numeral 3 denotes a transfer target, and 4 denotes an image line portion formed by the relief printing plate for high-definition printing of the present invention. 3 can use a light-transmitting base material such as glass or a resin film, a semiconductor substrate, or the like. In the present invention, when the pitch width of the target printed pattern (image portion) is a, the corresponding high-precision printing relief pattern (convex portion) pitch is n × a (n is an integer of 2 or more). ), The case where n = 2 is shown in FIG. 2B.

  The high-definition printing relief shown in FIG. 2B is formed by exposing and developing a photosensitive resin molded into a plate shape, or by cutting with a laser or a metal sword. Although a known method can be used, it is desirable to use a method using a photosensitive resin because of the ease of the method, and it is more desirable to use a water-soluble photosensitive resin because of solvent resistance.

  Next, an embodiment in the case of producing an organic EL element using the relief printing plate for high-definition printing and the method for producing an electronic device of the present invention will be described with reference to the drawings. The present invention is not limited to this. In particular, the printed pattern (image portion) and the high-definition relief printing plate pattern (convex portion) are described using a stripe pattern, but this is not a limitation, and the patterns are aligned at a constant pitch width. If it is. Although only n = 2 is shown, the present invention is not limited to this. In actuality, n = 2 to 4, and if 4 is exceeded, the number of printings or printing units increases, and work efficiency and registration accuracy are increased. Since it becomes inferior, it is not preferable.

FIG. 3 shows an example of an apparatus for manufacturing an organic EL element using the relief printing plate for high-definition printing of the present invention. For example, as shown in FIG. 3, the ink 13 for organic EL elements containing the organic light emitting material is replenished from the coating liquid replenishing device 11 to the inking device 12 on the relief printing plate, and the organic light emitting material replenished to the inking device 12 is supplied. Of the organic EL element ink 13 to be included, excess can be removed by the doctor device 14. As the coating liquid replenishing device, a coater such as a fountain roll, a slit coater, a die coater, or a gap coater, or a combination thereof can be used in addition to the dropping type replenishing device. In addition to the doctor roll, a doctor blade can also be used for the doctor device 14.

  After the excess ink is removed by the doctor device 14, at least the surface is inked into the cylinder 15 on which the relief printing plate for high-definition printing of the present invention is mounted. The inking to the relief printing plate for high-definition printing of the present invention may be performed at least on the projections that are the image line portions of the relief printing. The ink inked into the relief printing plate for high-definition printing of the present invention is transferred to the transfer medium 3 and printed. The ink 13 containing the organic light emitting material printed on the transfer medium 3 is dried to form an organic light emitting layer.

  After printing is performed by the printing apparatus including one printing unit illustrated in FIG. 3, the position of the convex portion 2 illustrated in FIG. 1B is the rotation of the cylinder 15 with respect to the letterpress mounted on the printing apparatus illustrated in FIG. 3. A relief plate having a pattern (convex portion) translated in the axial direction is mounted, and printing is performed using a printing apparatus including one printing unit shown in FIG.

  As a result, in the first printing, as shown in FIG. 5A, for example, a printed matter including the image line portion 4 with the pitch 2a is obtained on the transfer target 3, and in the second printing, for example, FIG. As shown in FIG. 5 (B), the desired high-definition printed matter formed by the image line portions 4 having the pitch a can be obtained.

  Further, as a different method, after printing is performed by a printing apparatus including one printing unit shown in FIG. 3, the cylinder 15 or the support base 16 on which the transfer target 3 is placed is translated in the rotation axis direction of the cylinder 15. As a result, the intended high-definition printed matter formed by the image line portions 4 having the pitch a as shown in FIG. 5B can be obtained. Note that an alignment mark is formed on the transfer target 3 in either case of the position of the convex portion of the relief printing plate or the support 16 is moved in parallel, and the alignment mark is observed with a CCD camera or the like mounted on the printing apparatus. By doing so, alignment can be performed.

  Furthermore, as another method, for example, as shown in FIG. 4, two types of relief printing plates can be mounted on one printing apparatus and printing can be performed by two printing units. In this case, two types of relief plates having a pattern (convex portion) translated in the direction of the rotation axis of the cylinder 15 with respect to the reference relief plate are used. Also in this result, by printing with the two printing units, in the first printing unit, as shown in FIG. 5A, a printed matter having the image line portion 4 with the pitch 2a is obtained on the transfer target 3, In the next printing unit, for example, as shown in FIG. 5B, a desired high-definition printed matter including the image line portions 4 having the pitch a can be obtained.

  FIG. 6 shows a cross-sectional view of the organic EL element manufactured by the organic EL element manufacturing apparatus (printing apparatus) shown in FIG.

  One light emitting unit 20 of the organic EL element includes a substrate 21, a conductive layer 22, a hole injection layer 23, an organic light emitting layer 24, and a cathode layer 25.

  Examples of the material forming the transparent conductive layer 22 include a composite oxide of indium and tin (hereinafter referred to as ITO). In addition, a semi-transparent metal such as aluminum, gold, or silver, or an organic compound such as polyaniline may be used.

Moreover, as the substrate 21, any substrate having an insulating property can be used, and for example, a glass substrate or a plastic film or sheet can be used. If a plastic film is used, an organic EL element can be manufactured by winding, and the element can be provided at a low cost. As the plastic, for example, polyethylene terephthalate, polypropylene, cycloolefin polymer, polyamide, polyethersulfone, polymethyl methacrylate, polycarbonate and the like can be used.

  In addition, as a material for forming the hole injection layer 23, a conductive polymer material such as a polyaniline derivative, a polythiophene derivative, a polyvinylcarbazole derivative, a mixture of poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid is used. Also good.

  The organic light emitting layer 24 is a layer containing an organic light emitter, and emits light when a voltage is applied. Examples of organic light emitting materials include coumarin, perylene, pyran, anthrone, porphyrin, quinacridone, N, N′-dialkyl substituted quinacridone, naphthalimide, N, N′-diaryl substituted pyrrolopyrrole. Organic light-emitting materials soluble in organic solvents such as iridium complexes, organic light-emitting materials dispersed in polymers such as polystyrene, polymethyl methacrylate, polyvinyl carbazole, polyarylenes, polyarylene vinylenes, Examples thereof include polymer organic light emitting materials such as polyfluorene-based materials.

  Furthermore, as the material forming the cathode layer 25, a material corresponding to the light emission characteristics of the organic light emitting layer 24 can be used. For example, simple metals such as lithium, magnesium, calcium, ytterbium, and aluminum, oxides thereof, gold, Examples include alloys with stable metals such as silver. Alternatively, a conductive oxide such as indium, zinc, or tin can be used.

  In order to manufacture the organic light emitting device described above using the relief printing plate of the present invention, a transfer substrate in which a transparent conductive layer 22 and a hole injection layer 23 are laminated on a substrate 20 is used. Ink 13 containing an organic light emitting material is used.

  The coating liquid containing the organic light emitting material is supplied to the convex portions of the relief printing as described above, and is printed on the above-described transfer target substrate. Solvents used in the coating solution that dissolve or disperse the luminescent material include, for example, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, isopropyl alcohol, ethyl acetate, butyl acetate, and chloroform. , Methylene chloride, dichloroethane, trichloroethane, tetrachloroethylene, water and the like alone or a mixed solvent thereof. In particular, an aromatic solvent and a halogen solvent are preferable because they are excellent in dissolving an organic light emitting material.

  Moreover, surfactant, antioxidant, a viscosity modifier, a ultraviolet absorber, a desiccant, etc. may be added to the coating liquid containing an organic luminescent material as needed.

  After the ink 13 containing the organic light emitting material is printed, the cathode layer 25 described above is formed. The cathode layer 25 can be formed by a known means such as an ink jet method in addition to the vacuum vapor deposition method.

  Specific examples of the present invention will be described below.

(Preparation of light emitting layer forming coating solution)
The polymeric fluorescent substance was dissolved in xylene so that the concentration of the coating solution was 1.0% by weight to prepare a light emitting layer forming coating solution. Here, the polymeric fluorescent substance refers to a light emitting material made of a poly (paraphenylene vinylene) derivative.
[Production of substrate to be transferred]
Poly (3,4) as a hole transport layer using a spin coater on a base material (manufactured by Geomat Co., Ltd.) formed with ITO having a surface resistivity of 15Ω on a glass substrate of 150 mm square and 0.4 mm thickness. Ethylenedioxythiophene / polystyrene sulfonic acid (PEDOT / PSS) was deposited to a thickness of 100 nm. Further, the PEDOT / PSS thin film thus formed was dried at 100 ° C. under reduced pressure for 1 hour to prepare a transfer substrate. The ITO pattern is a stripe pattern, and the ITO line width is 100 μm and the space portion is 400 μm.
[Preparation of high-definition letterpress]
Using a negative plate having a line width of 100 μm and a space width of 900 μm with respect to a commercially available water-soluble photocurable resin material, a printing relief plate was produced through the steps of exposure and development.
(Formation of organic light emitting layer)
After mounting the above-mentioned relief printing plate for high-definition printing on its own relief printing press, printing is performed, the stage on which the transfer object is placed is translated by 500 μm in the direction of the cylinder rotation axis, and printing is performed for the second time. It was. After the printed substrate was dried at 150 ° C. for 5 hours, 1 nm of calcium and 80 nm of aluminum were laminated as a cathode to obtain an organic EL element. When a voltage was applied to the obtained organic EL element to confirm the light emission state, good light emission was obtained.

  Below, the comparative example of this invention is demonstrated.

[When using a letterpress with n = 1]
Using a negative plate having a line width of 100 μm and a space width of 400 μm with respect to a commercially available water-soluble photocurable resin material, a relief printing plate was prepared through the steps of exposure and development. The above high-definition relief printing was mounted on an in-house relief printing press and printed. After the printed substrate was dried at 150 ° C. for 5 hours, 1 nm of calcium and 80 nm of aluminum were laminated as a cathode to obtain an organic EL element. When a voltage was applied to the obtained organic EL element and the state of light emission was confirmed, the coating liquid (ink) that had flowed into the relief had also been transferred onto the transferred material, so uniform light emission was obtained. There wasn't.

[When using a solvent-soluble photocurable resin]
Using a negative plate having a line width of 100 μm and a space width of 900 μm with respect to a commercially available solvent-soluble photocurable resin material, a relief printing plate was prepared through the steps of exposure and development. After mounting the above-mentioned relief printing plate for high-definition printing on its own relief printing press, printing is performed, the stage on which the transfer object is installed is translated by 500 μm in the direction of the cylinder rotation axis, and printing is performed for the second time. It was. After the printed substrate was dried at 150 ° C. for 5 hours, 1 nm of calcium and 80 nm of aluminum were laminated as a cathode to obtain an organic EL device. When a voltage was applied to confirm the light emission state, uniform line width could not be obtained due to the swelling of the plate, so uniform light emission could not be obtained.

The example of the relief printing plate for high-definition printing of this invention is represented typically, (A) is the perspective view, (B) is the sectional drawing. 1 schematically shows an example of a high-definition printing relief plate and a high-definition printed material according to the present invention, in which (A) is a plan view of the high-definition printed material and (B) is a plane of the high-definition printing relief plate. FIG. It is explanatory drawing which represented the example of the printing unit using the relief printing plate for high-definition printing of this invention by the side surface. It is explanatory drawing which represented the other example of the printing unit using the relief printing plate for high-definition printing of this invention by the side surface. FIG. 5 is a plan view showing an example of a high-definition printed material obtained by the printing unit shown in FIGS. 3 and 4, (A) is a plan view of the high-definition printed material obtained by the first printing, and (B) is It is a top view of the target high-definition letterpress. It is a sectional side view explaining the example of the organic EL element manufactured using the letterpress for high-definition printing of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Supporting body 2 ... Convex part of letterpress 3 ... Transfer object 4 ... Image line part of printed matter 5 ... Concave part of letterpress 11 ... Ink replenishing device 12 ... Inking device 13 ... Ink 14 ... ··· Doctor device 15 · · · Cylinder 16 · · · Support base 20 · · · One light emitting unit of organic EL element 21 · · · Substrate 22 · · · Transparent conductive layer 23 · · · Hole injection layer 24 · · · Organic light emitting layer 25 · · · Cathode layer

Claims (2)

A relief printing plate for transferring a ink containing a functional material to a substrate by a relief printing method to obtain a high-definition printed material, wherein image line portions of the high-definition printed material are aligned at a constant pitch width, and the pitch width Is a convex plate for high-definition printing, characterized in that the convex portion, which is the image line portion, has a pitch width of n × a (n is an integer of 2 or more). The convex part, which is a part, uses a high-definition printing relief plate having a pitch width of n × a in the rotation axis direction, supplies ink containing a functional material to the high-definition printing relief plate, and the supplied ink is It is transferred to a hard substrate by a pressure method, the letterpress for high-definition printing is translated in the rotation axis direction by a width a, and the same ink transfer is repeated n times, and the inking device is replenished with organic Excess ink among organic EL element-containing inks containing luminescent materials is supplied by a doctor device. Method for manufacturing an electronic device, and removing. An organic EL device obtained by the method for producing an electronic device according to claim 1.