JP5700043B2 - Method for forming organic thin film layer, method for producing organic electroluminescence element - Google Patents

Description

  The present invention relates to a method for forming an organic thin film by a coating method and a method for producing an organic electroluminescence element (hereinafter also referred to as an organic EL element) using this formation method.

  Conventionally, the following two coating methods are known as a method of coating a coating liquid on a continuously running belt-like substrate. One is a post-measurement type coating method in which an excess coating solution is discharged onto the substrate in advance, and then the excess is removed by some scraping means. As a post-measuring type coating method, a blade coating method, an air knife coating method, a wire bar coating method, a gravure coating method, a reverse coating method, and a reverse roll coating method are known.

  The other is a pre-weighing type coating method in which the coating liquid is discharged by an amount that forms a necessary coating liquid film, and the coating liquid is applied onto the substrate. As a pre-weighing type coating method, an extrusion coating method using a slit type die coater, a slide coating method using a slide coater, a curtain coating method, and a coating method using an inkjet head are known. Among the pre-weighing type coating devices, the slit type die coater can cope with high coating accuracy, high quality, high speed, thin film, suitability for multilayer coating, etc., for example, optical film, inkjet recording paper, It is used for the production of heat-developable recording materials and organic EL elements.

  Among these, in recent years, a coating method used for an organic EL element has attracted attention. An organic EL element is a thin film composed of an organic layer (single layer portion or multilayer portion) containing an organic light-emitting substance having a thickness of about 0.1 μm between a pair of anode and cathode formed on a substrate. Type all-solid-state device. When a relatively low voltage of about 2 V to 20 V is applied to such an organic EL element, electrons are injected into the organic layer from the cathode and holes are injected from the anode. It is known that light emission can be obtained by recombining electrons and holes in the light-emitting layer in the organic layer and releasing energy as light when the energy level returns from the conduction band to the valence band. This is a technology that is expected as a next-generation flat display and lighting.

  In order to improve productivity and reduce manufacturing costs, organic EL devices are manufactured by a method in which the organic layer is applied to a continuously running belt-like substrate (hereinafter also referred to as a web-like substrate) called a roll-to-roll method in recent years. Is being considered. In recent years, there has been a growing demand for higher functionality and thinner layers, uniform coating film thickness, and higher productivity.

  For example, when an organic layer (for example, a hole transport layer, a light emitting layer, etc.) constituting the organic EL element is formed by a coating method, the viscosity becomes low from the viewpoint of the performance of the organic EL element and the solubility of the material used. In many cases, the viscosity of the coating solution to be used is a low viscosity of 4.0 mPa · s or less. However, when such a low-viscosity material is used, it is difficult to avoid uneven drying. Are known. Among the organic layers, the thickness of the hole transport layer is 5 nm to 500 nm, and the thickness of one layer forming the light emitting layer is 2 nm to 100 nm. It is known to affect the performance of EL panels. For example, in the case where the light emitting layer is formed by a coating method, it is known that a variation in film thickness of several nm appears as light emission unevenness, and thus there is a high demand for uniform film thickness.

  As a cause of the occurrence of film thickness unevenness, it is known that the film thickness unevenness at the time of application described above and the drying unevenness at the time of drying (also referred to as wind ripples).

  Studies have been made on drying unevenness at the time of drying. For example, while conveying a web-shaped substrate coated with a coating liquid, in a drying furnace, hot air is sent as a laminar flow in a direction parallel to the substrate, without causing drying unevenness on the coated surface. A method for efficiently drying a coating film is known (for example, see Patent Document 1).

  Immediately after applying a liquid material on a substrate, a method is known in which a laminar airflow parallel to the substrate transport direction is ejected from a jet outlet of an airflow generation unit and dried (see, for example, Patent Document 2). ).

  After applying a coating solution containing a solvent to the belt-shaped substrate being transported, a laminar air flow is transported in the direction of transport of the substrate in each drying zone disposed between 0.2 m and 0.8 m from the coating position. It is divided into a plurality of drying zones equipped with air supply means to supply in the direction intersecting with the air, and it is carried into the transport port of the drying zone to produce at a faster drying speed than at least natural drying while suppressing slight drying unevenness. There is known a method of drying a coating film that can improve the property (for example, see Patent Document 3).

JP 2002-340479 A JP 2003-297469 A JP 2009-125633 A

However, it has been found that the method described in Patent Document 1 has the following problems.
1. Very high device accuracy is required to discharge uniform drying air.
2. Wind viscosity variation in the height direction is large, and low viscosity coating liquids of 10.0 mPa · s or less are liable to generate wind ripples and cannot be applied.

However, it has been found that the method described in Patent Document 2 has the following problems.
1. An airflow generation unit that generates a dry airflow is required for the applied pixels, and the drying capacity depends on the number of airflow generation unit nozzles. There is a problem in terms of accuracy and cost by increasing the number of airflow generation units.
2. In addition, when the distance between the airflow generation unit, the airflow generation unit, and the coating mechanism is short, the airflow may be disturbed due to the influence of air supply / exhaust generated from the adjacent airflow generation unit, and drying unevenness may occur.
However, it has been found that the method described in Patent Document 3 has the following problems.
1. A pressure difference is generated between the top plate and the base material and between the base material and the bottom plate, and uniform drying is difficult.
A low-viscosity coating liquid of 2.10.0 mPa · s or less is liable to generate wind ripples, and when the air current is applied in the direction crossing the transport direction, liquid deviation occurs and a uniform device cannot be produced.

  From this situation, the organic thin film layer forming coating solution is applied on the belt-like substrate that is continuously transported by the coating method to form an organic thin film layer having a stable film thickness without causing uneven drying. Development of a method for forming an organic thin film layer and a method for manufacturing an organic EL element by this method is desired.

  The present invention has been made in view of the above situation, and its purpose is to apply a coating liquid for forming an organic thin film layer by a coating method on a continuous belt-shaped substrate, and there is no occurrence of drying unevenness. An object of the present invention is to provide a method for forming an organic thin film layer for forming an organic thin film layer having a stable film thickness and a method for producing an organic EL element by this method.

  The above object of the present invention has been achieved by the following constitution.

1. Formation of an organic thin film layer having a coating step of applying a coating liquid for forming an organic thin film layer on a belt-like substrate supported and transported by a back roll, and a drying step of drying the coating film formed in the coating step In the method, the drying step uses a drying apparatus having a drying chamber on the back roll, and the height of the drying chamber from the surface of the back roll is 0 from the entrance to the exit of the drying chamber. It is set so as to change continuously within a range of 1 mm to 50 mm, and in the drying step, the coating film is dried by a laminar drying air formed by a suction method, and the laminar flow drying is performed. The method of forming an organic thin film layer, characterized in that the wind is flowing parallel to the length direction of the belt-like substrate and in the same direction as the transport direction .

  2. 2. The method for forming an organic thin film layer according to 1 above, wherein the drying chamber is depressurized.

3. The position where the coating film is transported into the drying chamber while the amount of solvent contained in the coating film is 20% or more with respect to the amount of solvent contained in the coating liquid for forming an organic thin film layer in the drying step. 3. The method for forming an organic thin film layer as described in 1 or 2 above, wherein

4). Wherein the drying step is characterized in that the amount of solvent contained in the coating film, 10.0 wt% 0.01 wt% of the solvent amount contained in the organic thin film layer forming coating solution 1 4. The method for forming an organic thin film layer according to any one of items 1 to 3 .

5. 5. The method for forming an organic thin film layer according to any one of 1 to 4 above, wherein the dry air has a Reynolds number (Re) of 70 to 1950 and an average flow velocity of 0.3 m / sec or more. .

6). Temperature of the drying air of the laminar flow state, the organic thin film layer forming coating liquid, from above, wherein the relative ambient temperature is ± 5 ℃ when applied on the strip-like base material 6. The method for forming an organic thin film layer according to any one of 5 above.

7). 7. The organic thin film layer according to any one of 1 to 6, wherein the organic layer has at least a first electrode, at least one organic layer, and a second electrode on a substrate. A method for producing an organic electroluminescent element, characterized by being formed by the method of

  Forming an organic thin film layer that forms an organic thin film layer having a stable film thickness by applying a coating solution for forming an organic thin film layer on a continuously conveyed belt-like substrate by a coating method, without causing uneven drying. The method and the manufacturing method of the organic EL element by this method were able to be provided.

It is the schematic which shows the formation method of the organic thin film layer which apply | coats the coating liquid for organic thin film layer formation on a strip | belt-shaped base material, and forms at least 1 layer of organic thin film layers. FIG. 2 is an enlarged schematic view of a portion indicated by X in FIG. 1. It is a schematic sectional drawing in alignment with AA 'of Fig.2 (a). It is the schematic of the manufacturing process which manufactures an organic EL element using the formation method of the organic thin film layer shown in FIGS.

  Embodiments of the present invention will be described with reference to FIGS. 1 to 4, but the present invention is not limited thereto. The drying step in the method for forming an organic thin film layer of the present invention is characterized by having a drying chamber on at least a backup roll. Below, it explains with the formation process of the organic thin film layer in this invention.

  FIG. 1 is a schematic view showing a method for forming an organic thin film layer in which an organic thin film layer is formed by applying a coating liquid for forming an organic thin film layer on a belt-like substrate.

  In the figure, reference numeral 4 denotes an organic thin film layer forming step. The forming process 4 includes a belt-shaped substrate supply process 4a, a coating process 4b, a first drying process 4c, a second drying process 4d, and a recovery process 4e.

  The supplying step 4a uses a feeding device (not shown), feeds the roll-shaped belt-like substrate 5 mounted on the feeding device (not shown), and supplies the belt-like substrate 5 to the coating step 4b.

  The coating process 4b uses a wet coating machine 4b1 and a back roll 4b2 that holds the belt-like substrate 5. The wet coating machine 4b1 applies the organic thin film layer forming coating solution 6 (see FIG. 2) on the back roll 4b2. This is applied to the belt-like substrate 5 to form a coating film for forming an organic thin film layer.

  Usable wet coaters include, for example, die coating method, screen printing method, flexographic printing method, ink jet method, Mayer bar method, cap coating method, spray coating method, casting method, roll coating method, bar coating method, gravure coating. It is possible to use a coating machine such as a method. Use of these wet coating machines can be appropriately selected according to the material of the organic thin film layer. This figure has shown the case of the die-coating system as the wet application machine 4b1.

  The vapor pressure of the solvent used for the coating liquid for forming the organic thin film layer is preferably 5 × 133 Pa to 50 × 133 Pa in consideration of the heating cost for maintaining the solvent drying temperature, the drying speed, and the like.

  The solvent is not particularly specified as long as it can dissolve the organic thin film layer, but alcohols such as methanol, ethanol, n-propyl alcohol, IPA, n-butyl alcohol, dimethylformamide, dimethylacetamide, THF, ketone , Ethers, acetone, diacetone alcohol, dioxane, polyethylene glycol, polypropylene glycol, polyalkylene glycol and other glycols, 2-pyrrolidone, xylene, toluene, chlorobenzene, dichlorobenzene, chloroform, dichloromethane, dichloroethane, n-butyl acetate , Isopropyl acetate, γ-butyl lactone, butyl cellosolve, cyclohexane, cyclohexanone, N-methyl-2-pyrrolidone, tetrachloroethane, nitrobenza Dehydrogenase, nitrobenzene, carbon disulfide, 2-heptanone, benzene, terpineol and water combination can be used.

  The viscosity of the coating solution for forming an organic thin film layer varies depending on the material of the organic thin film layer to be formed. However, in the present invention, considering the electrical characteristics of the organic thin film layer, the drying speed, etc., 0.3 mPa · s to 10.0 mPa · s. A viscosity shows the value measured with the Brookfield digital viscometer HV-50.

  The solid content concentration of the organic thin film layer forming coating solution varies depending on the material of the organic thin film layer to be formed. In the present invention, however, in consideration of the stability over time after preparation of the coating solution, 0.1% by mass to 2.0% by mass. % Is preferred.

  In the first drying step 4c, the drying device 4c1 is used, and the solvent is preliminarily removed from the organic thin film layer forming coating film formed in the coating step 4b. In the present invention, the first drying step 4c is referred to as a preliminary drying step for convenience. The preliminary drying step 4c will be described in detail with reference to FIGS.

  The second drying step 4d uses the drying device 4d1, and the organic thin film layer is formed by heating and drying the belt-like substrate 5 on which the organic thin film layer forming coating film processed in the preliminary drying step 4c is formed. Is done. There is no limitation in particular as drying apparatus 4d1, For example, a heater heating system, a heating air system, etc. are mentioned, It is possible to select suitably as needed. In the present invention, the second drying step 4d is referred to as a main drying step for convenience.

  The collecting step 4e uses a winding device (not shown), and collects the belt-like substrate 5 on which the organic thin film layer is formed in a winding roll shape around the core.

  In the present invention, the organic thin film layer means a thickness of 10 nm to 200 nm. The thickness can be measured with an optical interference type film thickness measuring instrument such as WykoNT9100 manufactured by Nippon Biko Co., Ltd.

  FIG. 2 is an enlarged schematic view of a portion indicated by X in FIG. FIG. 2A is an enlarged schematic perspective view of a portion indicated by X in FIG. FIG.2 (b) is a schematic plan view from the predrying apparatus side of Fig.2 (a).

  The preliminary drying step 4c is arranged on the back roll, and uses a drying device 4c1 having a drying chamber under reduced pressure. The drying device 4c1 includes a drying chamber 4c11 and a pressure control unit 4c12.

  The drying chamber 4c11 includes a side plate 4c111, a side plate 4c112, a top plate 4c113, a top plate 4c113, and a single mounting plate 4c114. The belt-like base material 5 side, the pressure control unit 4c12 side, and a wet coater. It has a bowl-like structure with the 4b1 side open. The drying chamber 4c11 is fixed to the side plate 4c124 (see FIG. 3) of the pressure control unit 4c12 via the mounting plate 4c114. In the drying chamber 4c11, a dry air in a laminar flow is configured to flow in the transport direction of the belt-shaped substrate 5 (the arrow direction in the figure).

  The pressure control unit 4c12 includes a side plate 4c121, a side plate 4c122, a side plate 4c123, a side plate 4c124 (see FIG. 3), and a top plate 4c125, and has a box-like structure in which the belt-like base material 5 side is opened. . Reference numeral 4c126 denotes a suction pipe attached to the top plate 4c125, which is connected to a suction pump (not shown).

  Reference numeral 6 denotes an organic thin film layer forming coating solution discharged from the wet coating machine 4b1. Reference numeral 7 denotes a coating film formed by applying the coating liquid 6 for forming an organic thin film layer.

  J indicates the width of the drying chamber 4c11. The width J is preferably 150% to 180% with respect to the coating width L of the coating liquid for forming an organic thin film layer in consideration of the influence of wind turbulence on the inner surface of the drying chamber and production efficiency. K indicates the width of the belt-like substrate 5.

  FIG. 3 is a schematic cross-sectional view along AA ′ of FIG. FIG. 3A is an enlarged schematic cross-sectional view along AA ′ of FIG. FIG. 3B is an enlarged schematic view of a portion indicated by Y in FIG.

  In the figure, 4c127 indicates a pressure control chamber. By depressurizing the pressure control chamber with a suction pump (not shown) through the suction pipe 4c126, the gas in the atmosphere for applying the coating liquid for forming an organic thin film layer flows into the drying air from the opening 4c115 of the drying chamber 4c11. It flows in the laminar flow state to the opening 4c116. Note that reducing the pressure control chamber means reducing the pressure in the pressure control chamber relative to the pressure in the coating chamber. In the present invention, the opening 4c115 is referred to as an entrance and the opening 4c116 is referred to as an exit.

  Reference numeral 4c115 denotes an opening on the wet coater 4b1 side of the drying chamber 4c11, and 4c116 denotes an opening on the pressure control unit 4c12 side of the drying chamber 4c11. The section of the atmosphere in which the coating solution for forming the organic thin film layer is applied from the opening 4c115 to the drying chamber 4c11.

  The inner surface of the drying chamber 4c11 preferably has a surface roughness of 10 μm or less in order to make the drying air flowing in the drying chamber 4c11 into a laminar flow. The surface roughness is a value measured by Keyence Corporation KS-1100. In addition, it is preferable that the periphery of the opening 4c115 and the opening 4c116 is free of concaves and convexes that affect the laminar flow state of the drying air flowing in the drying chamber 4c11, such as screw holes, joints, burrs, and the like.

  The temperature of the drying air flowing in the drying chamber 4c11 is determined based on the organic thin film layer on the belt-like substrate 5 in consideration of the convection of the coating liquid, the influence on the mechanical shaft runout accuracy such as the back roll, and the influence of the variation due to the heating mechanism. It is preferable that it is the atmospheric temperature which apply | coats the forming coating liquid. Atmospheric temperature refers to the temperature of the room in which it is applied. The ambient temperature is preferably 20 ° C. to 40 ° C. because the equipment cost increases when the temperature is too high, and a sufficient evaporation rate cannot be obtained when the temperature is too low.

  The state of the drying air flowing in the drying chamber 4c11 is preferably a laminar flow state. However, when the wind speed is too low, the substrate is easily affected by the conveying air of the base material, and the drying speed becomes slow. Therefore, the Reynolds number (Re) is preferably 70 to 1950 and the average flow velocity is preferably 0.3 m / sec or more. More preferably, they are 70 or more and 1000 or less, Most preferably, they are 70 or more and 750 or less. If the Reynolds number is less than 70, it takes too much time for drying since the average flow velocity of the drying air approaches 0 m / sec as a substantial drying condition. Therefore, the lower limit of the Reynolds number is preferably 70 or more. On the other hand, when the Reynolds number is more than 1950, a turbulent / laminar flow transition region is formed, and drying proceeds in a state where the liquid interface of the coating liquid is disturbed, which may cause some unevenness in the coating film. Therefore, the upper limit of the Reynolds number is preferably 1950 or less.

The Reynolds number (Re) is the rectangular channel equivalent diameter De = 2ab / (a + b), where the width and height of the drying chamber 4c11 are a and b, respectively, and the flow rate is the measured value (m / sec) shown below. The value which calculated | required kinematic viscosity of gas ((micro | micron | mu) in formula (micro | micron | mu :: the viscosity of a drying wind, (rho): the density of a drying wind)) by 13.35 * 10 < ^-6 > (m < ² > * s < ^-1 >) is shown. The flow velocity indicates a value obtained from Kanomax Anemo Master Anemometer 6003.

  Adjustment of the Reynolds number (Re) and average flow velocity of the drying air flowing in the drying chamber 4c11 is possible by controlling the pressure in the pressure control chamber.

  In the preliminary drying step 4c, the amount of solvent contained in the organic thin film layer-forming coating film formed on the belt-like substrate 5 is adjusted to the amount of solvent in the organic thin film layer-forming coating solution in consideration of the occurrence of wind ripples. On the other hand, it is preferable that the coating film is disposed at a position above the back roll so that the coating film is conveyed into the drying chamber between 20% by mass or more.

  The amount of the solvent contained in the coating film for forming the organic thin film layer when exiting from the opening 4c116 in the preliminary drying step 4c is determined in consideration of the distance necessary for drying in the main drying step 4d, film thickness unevenness, and the like. It is preferable that it is 0.01 mass% to 10.0 mass% of the amount of solvent contained in the coating liquid for coating.

  The amount of solvent contained in the organic thin film layer-forming coating film indicates a value measured by the method described below.

  The amount of the solvent was calculated by measuring the wet film thickness using a double scan type laser displacement meter LT-9500 manufactured by Keyence Corporation.

  M indicates the height (indicating the height of the drying chamber) from the surface of the back roll 4b2 of the opening 4c115 to the inner surface 4c117 of the top plate 4c113.

  N indicates the height from the surface of the back roll 4b2 of the opening 4c116 to the inner surface 4c117 of the top plate 4c113 (indicating the height of the drying chamber).

  The height from the opening (entrance) 4c115 to the opening (exit) 4c116 continuously changes from 0.1 mm to 50 mm in consideration of drying of the coating film in order to make the drying air laminar flow. It is necessary. Note that “continuously changing” means monotonously continuously increasing or decreasing. Even if the direction of change changes in the middle, it may not change. Specifically, there should be no step of 1 mm or more.

  Further, the height from the surface of the back roll from the opening (entrance) 4c115 to the opening (exit) 4c116 may be the same.

  Other symbols are the same as those in FIG.

  The material forming the drying chamber 4c11 is not particularly limited as long as it is a material that is not affected by the solvent to be evaporated, and examples thereof include stainless steel, aluminum, and quartz glass. Among these, quartz glass is preferably used in consideration of visibility, solvent resistance, and accuracy.

The following effects can be obtained by the method for forming an organic thin film layer of the present invention shown in FIGS. 1. There is no occurrence of uneven drying, and a long light emission lifetime is obtained by having a stable film thickness of the organic thin film layer.
2. The organic thin film layer can be continuously dried, and the cost is low.

  The organic thin film layer forming method of the present invention shown in FIGS. 1 to 3 is applied within each layer constituting an antireflection film having a hard coat layer, an antireflection layer, etc., an optical film, and an organic EL element. Applicable to organic layers (eg, hole transport layer, light-emitting layer, etc.) that can be formed by various methods, color filters used in liquid crystal displays, optical filters, various coating films, inkjet recording paper, thermal development recording materials, etc. Is possible.

  A method for manufacturing an organic EL element using the method for forming an organic thin film layer shown in FIGS. 1 to 3 of the present invention will be described below.

  FIG. 4 is a schematic view of a manufacturing process for manufacturing an organic EL element using the method for forming an organic thin film layer shown in FIGS. In the present invention, the organic EL element refers to the structure of substrate / first electrode / functional layer (hole transport layer / light emitting layer / electron transport layer) / second electrode. The preliminary drying step shown in the figure is the same as the preliminary drying step 4c shown in FIGS. 2 and 3, and the main drying step is the same as the main drying step 4d shown in FIG.

  In the figure, reference numeral 1 denotes a manufacturing process of an organic EL element. The manufacturing process 1 includes a first supply process 101, a hole transport layer formation process 102, a light emitting layer formation process 103, an electron transport layer formation process 104, a first recovery process 105, a second supply process 106, A second electrode forming step 107 and a second recovery step 108 are included.

  The first supply step 101 uses a roll-like strip-shaped substrate 2a feeding device (not shown) and an accumulator 101a, and continuously feeds the strip-shaped substrate 2 to the hole transport layer forming step 102 of the next step. It is like. The accumulator 101a is provided for speed adjustment with the hole transport layer forming step 102 in the next step.

  The hole transport layer forming step 102 includes a coating step 102a and a drying step 102b, and uses an accumulator 102c. In the hole transport layer forming step 102, a hole transport layer forming coating solution is applied on the first electrode except for the first electrode extraction electrode portion of the band-shaped substrate 2 on which the first electrode is formed, and the drying step. A hole transport layer is formed through 102b and conveyed to the next light emitting layer forming step 103. The accumulator 102c is arranged for speed adjustment with the light emitting layer forming step 103 of the next step.

  The coating process 102 a uses a wet coating machine 102 a 1 and a backup roll 102 a 2 that holds the belt-shaped substrate 2. The coating liquid for forming a hole transport layer by the wet coater 102a1 detects an alignment mark (not shown) attached to the belt-like substrate 2 with an alignment mark detector (not shown), and detects the first electrode (anode). It is applied on a first electrode (anode) (not shown) that has already been formed except for the extraction electrode (not shown). Usable wet coaters include, for example, die coating method, screen printing method, flexographic printing method, ink jet method, Mayer bar method, cap coating method, spray coating method, casting method, roll coating method, bar coating method, gravure coating. It is possible to use a coating machine such as a method. The use of these wet coaters can be appropriately selected according to the material of the hole transport layer. In this figure, since the organic EL element used for illumination is taken as an example, the wet coater 102a1 is of the whole surface coating type. However, when the organic EL panel is a full color system, it is patterned and formed. For example, an inkjet method, a flexographic printing method, an offset printing method, a gravure printing method, a screen printing method in order to apply a light emitting layer on the first electrode (anode) in accordance with the pattern of the first electrode (anode) that has been applied. It is possible to use various coating apparatuses used for a spray coating method using a mask.

  The drying step 102b includes a preliminary drying step 102b1 and a main drying step 102b2. The preliminary drying step 102b1 is the same as the preliminary drying step 4c shown in FIGS.

  The main drying step 102b2 uses a drying device 102b21 and a heat treatment device 102b22. There is no limitation in particular as drying apparatus 102b21, For example, a heating system, a heating air system, a vacuum drying system etc. are mentioned, It can be suitably selected as needed.

  The heat treatment apparatus 102b22 heats the hole transport layer forming coating film (not shown) from the back surface side of the belt-like substrate 2 by the back surface heat transfer method. As a heat treatment condition for the hole transport layer (not shown) in the heat treatment apparatus 102b22, considering the improvement of the smoothness of the hole transport layer, the removal of the residual solvent, etc., the glass transition of the resin constituting the hole transport layer It is preferable to perform the back surface heat transfer type heat treatment at a temperature that is from −30 ° C. to + 30 ° C. and does not exceed the decomposition temperature of the organic compound constituting the hole transport layer.

  It is preferable to dispose antistatic means 102b3 between the drying step 102b and the light emitting layer forming step 103 as necessary.

Antistatic means The antistatic means 102b3 has a non-contact type antistatic device 102b31 and a contact type antistatic device 102b32. Examples of the non-contact type antistatic device 102b31 include a non-contact type ionizer. The type of ionizer is not particularly limited, and the ion generation method may be either an AC method or a DC method. An AC type, a double DC type, a pulsed AC type, and a soft X-ray type can be used, but the AC type is particularly preferable from the viewpoint of precise static elimination. Air or N ₂ is used as the injection gas required when using the AC type, but it is preferable to use N ₂ with sufficiently high purity. From the viewpoint of in-line operation, the blower type or the gun type is selected.

  As the contact-type antistatic device 102b32, a static eliminating roll or a conductive brush connected to the ground is used. The static elimination roll as the static eliminator is grounded and removes the surface charge by rotatingly contacting the neutralized surface. Such static elimination rolls include rolls made of elastic plastic or rubber mixed with conductive materials such as carbon black, metal powder, and metal fibers in addition to rolls made of metal such as aluminum, copper, nickel, and stainless steel. used. In particular, in order to improve the contact with the belt-shaped substrate 2, an elastic material is preferable. Examples of the conductive brush connected to the earth include a neutralizing bar or a neutralizing yarn structure having a brush member made of conductive fibers arranged in a line or a linear metal brush. The neutralization bar is not particularly limited, but a corona discharge type is preferably used. For example, SJ-B manufactured by Keyence Corporation is used. There is no particular limitation on the neutralizing yarn, but usually a flexible thread-like one is preferably used. For example, a stainless steel neutralizing fiber Naslon manufactured by Nippon Seisen Co., Ltd. can be mentioned as an example.

  The non-contact type antistatic device 102b31 is preferably used on the side of the hole transport layer formed on the belt-like substrate 2, and the contact type antistatic device 102b32 is preferably used on the back side of the belt-like substrate 2.

  The film thickness of the hole transport layer is appropriately adjusted in consideration of light emission efficiency, lifetime, and the like.

  The light emitting layer forming step 103 includes a coating step 103a and a drying step 103b, and uses an accumulator 103c. The accumulator 103c is provided for speed adjustment with the electron transport layer forming step 104 in the next step. In the light emitting layer forming step 103, a coating solution for forming a light emitting layer is applied on the hole transport layer except for the first electrode extraction electrode portion of the belt-like substrate 2 on which the hole transport layer is formed, and the drying step 103b is performed. After that, the light emitting layer is formed and conveyed to the electron transport layer forming step 104 of the next step.

  The coating process 103 a uses a wet coating machine 103 a 1 and a backup roll 103 a 2 that holds the belt-shaped substrate 2. The coating solution for forming the light emitting layer by the wet coater 103a1 detects an alignment mark (not shown) attached to the belt-like substrate 2 with an alignment mark detector (not shown), and takes out the first electrode (anode). It is applied on a hole transport layer (not shown) that has already been formed except for (not shown). As a wet coater that can be used, the same wet coater as that used in the coating step 102a of the hole transport layer forming step 102 can be used.

  The drying process 103b includes a preliminary drying process 103b1 and a main drying process 103b2. The preliminary drying step 103b1 has the same configuration as the preliminary drying step 102b1 of the hole transport layer forming step 102.

  The main drying step 103b2 uses a drying device 103b21 and a heat treatment device 103b22. There is no limitation in particular as drying apparatus 103b21, For example, a heating system, a heating air system, etc. are mentioned, It can be suitably selected as needed.

  The heat treatment apparatus 103b22 heats the light emitting layer forming coating film (not shown) from the back surface side of the belt-like substrate 2 by the back surface heat transfer method. As the heat treatment conditions for the light emitting layer (not shown) in the heat treatment apparatus 103b22, the glass transition temperature of the resin constituting the light emitting layer is considered in consideration of improvement in smoothness of the light emitting layer, removal of residual solvent, curing of the light emitting layer, and the like. On the other hand, it is preferable to perform the heat transfer method of the back surface heat transfer method at a temperature which does not exceed the decomposition temperature of the organic compound constituting the light emitting layer from −30 ° C. to + 30 ° C.

  It is preferable to dispose the same antistatic means 103b3 as the antistatic means 102b3 between the drying step 103b and the electron transport layer forming step 104 as necessary.

  The film thickness of the light emitting layer is usually selected in the range of 5 nm to 1 μm, preferably 20 nm to 100 nm in consideration of the film uniformity, device lifetime, light emission efficiency, and the like.

  When the light emitting layer (not shown) is a multilayer, it is necessary to arrange an application process and a drying process according to the number of layers. For example, a white element can be manufactured by forming a light emitting layer in multiple layers. In the present invention, the light emitting layer refers to a blue light emitting layer, a green light emitting layer, and a red light emitting layer. There is no restriction | limiting in particular as a lamination order in the case of laminating | stacking a light emitting layer, You may have a nonluminous intermediate | middle layer between each light emitting layer. Also, when four or more light emitting layers are provided, for example, blue light emitting layer / green light emitting layer / red light emitting layer / blue light emitting layer, blue light emitting layer / green light emitting layer / red light emitting layer / blue light emitting from the order close to the anode. Layered / green light emitting layer, blue light emitting layer / green light emitting layer / red light emitting layer / blue light emitting layer / green light emitting layer / red light emitting layer, etc. It is preferable for improving luminance stability.

  The total thickness of the light emitting layer is not particularly limited, but is usually selected in the range of 2 nm to 5 μm, preferably 2 nm to 200 nm in consideration of the film homogeneity, the voltage required for light emission, and the like. Further, it is preferably in the range of 10 nm to 100 nm. A film thickness of 100 nm or less is preferable because it has the effect of improving the stability of the emission color with respect to the driving current as well as the voltage surface.

  The electron transport layer forming step 104 includes a coating step 104a and a drying step 104b, and uses an accumulator 104c. The accumulator 104c is disposed for speed adjustment with the first recovery step 105 of the next step. In the electron transport layer forming step 104, a coating liquid for forming an electron transport layer is applied on the light emitting layer except for the first electrode extraction electrode portion of the belt-like substrate 2 on which the light emitting layer is formed, and the electron is transported through the drying step 104b. A transport layer is formed, conveyed to the first recovery step 105 of the next step, and once recovered.

  The coating process 104 a uses a wet coating machine 104 a 1 and a backup roll 104 a 2 that holds the belt-shaped substrate 2. The coating liquid for forming an electron transport layer by the wet coater 104a1 detects an alignment mark (not shown) attached to the belt-like substrate 2 with an alignment mark detector (not shown) and takes out the first electrode (anode). It is applied on a light-emitting layer (not shown) that has already been formed except for electrodes (not shown). As a wet coater that can be used, the same wet coater as that used in the coating step 102a of the hole transport layer forming step 102 can be used.

  The drying process 104b includes a preliminary drying process 104b1 and a main drying process 104b2. The preliminary drying step 104b1 has the same configuration as the preliminary drying step 102b1 of the hole transport layer forming step 102.

  The main drying step 104b2 uses a drying device 104b21 and a heat treatment device 104b22. There is no limitation in particular as drying apparatus 104b21, For example, a heating system, a heating air system, etc. are mentioned, It is possible to select suitably as needed.

  The heat treatment apparatus 104b22 heats a coating film for forming an electron transport layer (not shown) from the back surface side of the belt-like substrate 2 by a back surface heat transfer method. Resin that constitutes the electron transport layer in consideration of heat treatment conditions for the electron transport layer (not shown) in the heat treatment apparatus 104b22, such as improvement of the smoothness of the electron transport layer, removal of residual solvent, and curing of the electron transport layer. It is preferable to perform the back-surface heat transfer type heat treatment at −30 ° C. to + 30 ° C. with respect to the glass transition temperature, and at a temperature not exceeding the decomposition temperature of the organic compound constituting the electron transport layer.

  It is preferable to dispose the same antistatic means 104b3 as the antistatic means 102b3 between the drying process 104b and the first recovery process 105 as necessary.

  The film thickness of the electron transport layer is appropriately adjusted in consideration of the light emission efficiency, the lifetime, and the like.

  The second supply step 106 uses an unwinding device (not shown) of the roll-shaped belt-like substrate 2a formed up to the electron transport layer and wound up in a roll shape, and an accumulator 106a, and forms the second electrode in the next step. In step 107, the belt-like substrate 2 on which the electron transport layer is formed is fed out. The accumulator 106a is arranged for speed adjustment with the second electrode forming step 107 of the next step.

  The second electrode forming step 107 includes a vapor deposition apparatus 107a having an evaporation source container 107b and an accumulator 107c. The accumulator 107c is arranged for speed adjustment with the second recovery step 108 of the next step.

  In the second electrode formation step 107, an alignment mark (not shown) attached to the belt-like substrate 2 on which the electron transport layer supplied from the second supply step 106 is formed is read with a detection device (not shown). A second electrode (cathode) (not shown) having a take-out electrode (not shown) at a position determined by the vapor deposition device 107a in accordance with information from a detection device (not shown) is already formed with an electron injection layer (not shown). A mask pattern is formed on the film. The sheet resistance as the second electrode (cathode) is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 nm to 200 nm. At this stage, an organic EL element 3 having a configuration of base material / first electrode (anode) / hole transport layer / light emitting layer / electron injection layer / second electrode (cathode) is completed. Thereafter, the organic EL panel is manufactured by sealing the organic EL element with a sealing material.

  The method for forming the second electrode (cathode) is not particularly limited. For example, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma polymerization method A plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

  The organic EL device in which the hole transport layer, the light-emitting layer, and the electron transport layer are formed by a wet coating method by the method for forming an organic thin film layer of the present invention can be formed stably, and the organic EL device has stable performance. The device can be manufactured.

  This figure shows the case where the hole transport layer forming process is divided into the electron transport layer forming process and the second electrode forming process, but the process from the hole transport layer forming process to the second electrode forming process may be continued. Is possible.

  Below, it attaches and demonstrates to the material concerning the product manufactured by the formation method of the organic thin film layer of this invention.

Organic EL Element The materials used when producing the organic EL element by the coating method of the present invention are described in International Publication No. 06/100908, JP 2006-294536 A, JP 2007-73332 A, and the like. It is possible to use known materials.

Others The materials used when producing the antireflection film and the optical film by the coating method of the present invention are disclosed in JP-A-2008-296421, 2008-224003, 2008-224718, 2008-. It is possible to use known materials described in JP-A-200600, 2007-098833, 2006-293201, and 2006-285217.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these. In addition, although the display of "part" or "%" is used in an Example, unless there is particular notice, it represents "mass part" or "mass%".

Example 1
(Preparation of strip-shaped substrate)
A polyethylene terephthalate film (Teijin-DuPont film, hereinafter abbreviated as PET) having a thickness of 100 μm, a width of 200 mm, and a length of 500 m was prepared as a belt-like substrate.

(Formation of first electrode (ITO film))
An ITO film having a thickness of 100 nm was formed on the prepared belt-like substrate using a sputtering apparatus.

(Preparation of coating solution for organic thin film layer formation)
A commercially available dye, C.I. I. A coating solution in which 1.5 parts by mass of Acid Red 249 was dissolved was prepared, and the amount of polyvinyl butyrate (PVB) added was adjusted so that the viscosity was 1.0 mP · s to prepare a coating solution. The viscosity of the coating solution is a value measured at a temperature of 25 ° C. using an E-type viscometer VISCONIC ED type manufactured by Toki Sangyo Co., Ltd. and a controller E-200 type manufactured by the same company.

(Preparation of slit type die coater)
The slit type die coater shown below was prepared.

Slit die coater width 170mm
Slit gap O 100μm
Application width 100mm
(Application)
The ITO film formed on the prepared belt-like substrate supported by the back roll having a diameter of 300 mm using the slit type die coater prepared in the manufacturing process shown in FIG. A coating film for forming an organic thin film layer having a wet film thickness of 6 μm is formed by coating at a coating speed of 1.0 m / min to 10.0 m / min. 2 and 3 using a drying device in which the height from the surface of the roll was continuously changed, and then the temperature was 120 ° C. and the average wind speed was 0.3 m / min. The film was dried at a sec. 101 to 110. The dry film thickness (film thickness after drying) was 100 nm. In addition, the amount of the solvent contained in the coating film for forming an organic thin film layer when entering the preliminary drying step was 95.0% with respect to the amount of the solvent contained in the coating solution for forming an organic thin film layer.

  The amount of solvent contained in the coating film for forming an organic thin film layer before entering the preliminary drying step was a value calculated from a wet film thickness using a Keyence double scan type laser displacement meter LT-9500.

  The amount of solvent contained after passing through the preliminary drying step was 1.2% by mass.

  The amount of solvent contained in the coating film for forming an organic thin film layer after passing through the preliminary drying step indicates a ratio (% by mass) to the amount of solvent contained in the coating solution for forming an organic thin film layer.

  The wet film thickness means a theoretical film thickness calculated by the following equation.

Wet film thickness = coating liquid supply flow rate / (coating width x coating speed)
The coating speed was measured with a laser Doppler speed meter LV203 manufactured by Mitsubishi Electric Corporation.

(Application conditions)
As the coating conditions, the coating width was 100 mm, the coating length was 50 m, and the coating temperature was 25 ° C.

Predrying process conditions Temperature of drying air flowing through the drying chamber: 25 ° C
Distance from entrance to exit of drying chamber: 200mm
Surface roughness (Ra) of the inner surface of the drying chamber: 5 μm
Ratio (%) to coating width of coating liquid for forming organic thin film layer in drying chamber: 150%
Decompression degree of the drying chamber: 30 Pa
The direction in which the drying air flows was the same as the transport direction of the belt-shaped substrate.

Preparation of Comparative Sample A comparative sample No. was formed by forming an organic thin film layer under the same conditions except that the preliminary drying step was not used and the drying step was performed at a temperature of 120 ° C. under the same conditions. 111.

Evaluation Each sample No. Table 1 shows the results from 101 to 111, with samples taken from the beginning 5 m and the end 5 m, measuring the film thickness stability by the measurement method shown below, and evaluating according to the evaluation rank shown below.

Measuring method of film thickness stability Since the relationship between the concentration and the film thickness is linear, use Konica Minolta Konica Densitometer PDM-7 to measure the concentration at 10 mm intervals in the width direction. The variation in density at 31 points was calculated as the film thickness stability by the following formula.

Film thickness stability (variation) = ((maximum density−minimum density) / average density) × 100
Evaluation rank of film thickness stability (variation) ◎: variation is less than 1.0 ○: variation is 1.0 or more and less than 3.0 Δ: variation is 3.0 or more and less than 5.0 ×: variation is 5. 0 or more

  After coating the coating solution for forming an organic thin film layer on the ITO film formed on the belt-shaped substrate to form a coating film for forming the organic thin film layer, the surface of the back roll from the entrance to the exit on the back roll Uses a drying device that has a drying chamber whose height is continuously increased monotonically from 0.1 mm to 10.0 mm, and uses a drying device that depressurizes the drying chamber, and passes through a preliminary drying process in which laminar drying air flows. Sample No. 2 was dried in this drying step to form an organic thin film layer. It was confirmed that Nos. 102 to 109 showed excellent film thickness stability.

  The drying chamber in which the height from the surface of the back roll at the entrance is 0.07 mm and the height from the surface of the back roll at the exit is 20.0 mm continuously and monotonously on the drying chamber in the preliminary drying step. Sample No. prepared using a drying apparatus having a drying chamber under reduced pressure. No. 101 is a sample No. of the present invention with a variation in film thickness. Compared with 102 to 109, it was confirmed that it was slightly inferior although it was not a practical problem.

  On the drying chamber in the preliminary drying process, there is a drying chamber in which the height from the surface of the back roll at the entrance is 20.0 mm and the height from the surface of the back roll at the exit is 55.0 mm. Sample No. prepared using a drying apparatus having a drying chamber under reduced pressure. No. 109 shows a variation in film thickness in the sample No. of the present invention. Compared with 102 to 109, it was confirmed that it was slightly inferior although it was not a practical problem.

  After applying the organic thin film layer forming coating liquid on the ITO film formed on the belt-shaped substrate to form the organic thin film layer forming coating film, drying the heated laminar flow without using the preliminary drying step Sample No. produced by drying with wind No. 111 is a film flowing, and the film thickness stability is the sample No. of the present invention. It was confirmed to be inferior to 101 to 110. The effectiveness of the present invention was confirmed.

Example 2
(Preparation of strip-shaped substrate)
The same belt-like substrate as in Example 1 was prepared.

(Formation of first electrode (ITO film))
A first electrode (ITO film) was formed on a strip-shaped substrate prepared by the same method as in Example 1.

(Preparation of coating solution for organic thin film layer formation)
The same organic thin film layer forming coating solution as in Example 1 was prepared.

(Application)
The same slit type die coater as used in Example 1 was used, and in the production process shown in FIG. The amount of the solvent contained in the coating film for forming an organic thin film layer after coating at 10.0 m / min to form a coating film for forming an organic thin film layer having a wet film thickness of 6.0 μm and passing through a preliminary drying step The sample Nos. Prepared in Example 1 are the same as those shown in Table 2. An organic thin film layer was formed on the belt-like substrate by the same method as in No. 106, and Sample No. 201 to 208. The amount of solvent contained in the organic thin film layer-forming coating film after passing through the preliminary drying step is adjusted from 0.007 to 10.5% by mass from the surface of the back roll from the entrance to the exit of the drying chamber. This was carried out by changing the height, the pressure in the pressure control chamber in the drying apparatus, the conveyance speed, and the like.

  The amount of solvent contained in the coating film for forming an organic thin film layer after passing through the preliminary drying step indicates a ratio (% by mass) to the amount of solvent contained in the coating solution for forming an organic thin film layer.

  The wet film thickness means the same theoretical film thickness as in Example 1, and shows a value measured by the same method as in Example 1. The coating speed was measured with a laser Doppler speed meter LV203 manufactured by Mitsubishi Electric Corporation.

(Application conditions)
The coating conditions were the same as in Example 1.

Evaluation Each sample No. From Table 201 to 208, samples were extracted from the beginning 5 m and the end 5 m, the film thickness stability was measured by the same method as in Example 1, and the results evaluated according to the same evaluation rank as in Example 1 are shown in Table 2. Show.

  After the organic thin film layer forming coating solution is applied on the ITO film formed on the belt-shaped substrate to form the organic thin film layer forming coating film, it is passed through a preliminary drying step in which laminar drying air flows. The amount of the solvent contained in the coating film for forming an organic thin film layer after passing through the preliminary drying step is 0.01% by mass to 10.0% by mass of the amount of the solvent contained in the coating solution for forming an organic thin film layer. %, In which the organic thin film layer was formed by drying in this drying step. It was confirmed that 202 to 207 exhibited excellent film thickness stability.

  After the organic thin film layer forming coating solution is applied on the ITO film formed on the belt-shaped substrate to form the organic thin film layer forming coating film, it is passed through a preliminary drying step in which laminar drying air flows. In this state, the amount of the solvent contained in the coating film for forming an organic thin film layer after passing through the preliminary drying step is 0.007% by mass of the amount of the solvent contained in the coating solution for forming an organic thin film layer. Sample No. which was dried in the process and formed an organic thin film layer. No. 201 has a film thickness stability of Sample No. It was confirmed that it was inferior to 202 to 207 to the extent that there was no practical problem.

  After the organic thin film layer forming coating solution is applied on the ITO film formed on the belt-shaped substrate to form the organic thin film layer forming coating film, it is passed through a preliminary drying step in which laminar drying air flows. The amount of solvent contained in the coating film for forming an organic thin film layer after passing through the preliminary drying step is 7% by mass of the amount of solvent contained in the coating solution for forming an organic thin film layer. Sample No. dried to form an organic thin film layer No. 208 has a film thickness stability of Sample No. It was confirmed that it was inferior to 202 to 207 to the extent that there was no practical problem.

  After applying the organic thin film layer forming coating liquid on the ITO film formed on the belt-shaped substrate to form the organic thin film layer forming coating film, drying the heated laminar flow without using the preliminary drying step Sample No. produced by drying with wind 209 indicates that the film flows, and the film thickness stability of the sample No. 209 of the present invention. It was confirmed that it was inferior to 201-208. The effectiveness of the present invention was confirmed.

Example 3
(Preparation of strip-shaped substrate)
The same belt-like substrate as in Example 1 was prepared.

(Formation of first electrode (ITO film))
A first electrode (ITO film) was formed on a strip-shaped substrate prepared by the same method as in Example 1.

(Preparation of coating solution for organic thin film layer formation)
The same organic thin film layer forming coating solution as in Example 1 was prepared.

(Application)
The same slit type die coater as used in Example 1 was used, and in the production process shown in FIG. To 10.0 m / min to form a coating film for forming an organic thin film layer having a wet film thickness of 6.0 μm. As shown in Table 3, the organic thin film before entering the preliminary drying step shown in FIGS. The residual solvent amount of the coating film for layer formation was processed by changing the transport speed of the belt-shaped substrate and the distance between the slit die coater and the opening of the pre-drying device, and subsequently dried at a temperature of 120 ° C in the main drying step. An organic thin film layer was formed and sample No. 301 to 308. The dry film thickness (film thickness after drying) was 100 nm. The amount of solvent contained in the coating film for forming an organic thin film layer before entering the preliminary drying step indicates a ratio (% by mass) to the amount of solvent contained in the coating solution for forming an organic thin film layer.

  The value measured by the same method as in Example 1 was used as the amount of solvent contained in the coating film for forming an organic thin film layer before entering the preliminary drying step.

  The wet film thickness means the same theoretical film thickness as in Example 1, and shows a value measured by the same method as in Example 1. The theoretical film thickness calculated by the following formula.

  The coating speed was measured with a laser Doppler speed meter LV203 manufactured by Mitsubishi Electric Corporation.

(Application conditions)
The coating conditions were the same as in Example 1.

  The amount of solvent contained in the organic thin film layer coating film when leaving the pre-drying process is the height from the surface of the back roll from the entrance to the exit of the drying chamber, the pressure in the pressure control chamber in the drying device, and the conveyance By changing the speed, etc., the content was 1.2% by mass with respect to the amount of solvent contained in the coating solution for forming an organic thin film layer.

Evaluation Each sample No. Table 3 shows the results of 301 to 308, samples taken from the beginning 5 m and the end 5 m, the film thickness stability was measured by the same method as in Example 1, and evaluated with the same evaluation rank as Example 1. .

  Sample No. prepared by transporting to the pre-drying step when the amount of solvent in the amount of solvent contained in the coating film for forming an organic thin film layer is 20% by mass or more with respect to the amount of solvent contained in the coating solution for forming an organic thin film layer . It was confirmed that 301 to 307 showed excellent performance in film thickness stability. The effectiveness of the present invention was confirmed.

Example 4
Sample Nos. Prepared in Example 1 except that the temperature of the drying air in the preliminary drying step was changed as shown in Table 4. An organic thin film layer was formed under the same conditions as in Sample No. 106. 401 to 407. In addition, the atmospheric temperature at the time of application | coating was 25 degreeC.

Evaluation Each sample No. From 401 to 407, samples were extracted from the beginning 5 m and the end 5 m, the film thickness stability was measured by the same method as in Example 1, and the results evaluated with the same evaluation rank as in Example 1 are shown in Table 4. Show.

  The temperature of the laminar drying air is set to the atmospheric temperature (25 ° C ± 5 ° C) when the organic thin film layer forming coating solution is applied onto the belt-like substrate, thereby suppressing thermal convection of the coating solution film. It was confirmed that the performance was excellent in thickness stability. The effectiveness of the present invention was confirmed.

Example 5
Table 5 shows the Reynolds number (Re) and the average flow rate of the drying air in the preliminary drying process by changing the ratio of the drying air temperature, the drying air flow height, and the drying air flow passage to the coating width of the organic thin film layer forming coating liquid. Sample Nos. Produced in Example 1 were all changed except as shown. An organic thin film layer was formed under the same conditions as in Sample No. 106. 501 to 512.

  The Re number is represented by the following formula.

Re = ρvd / μ
It is assumed that the equivalent diameter is d, the density ρ of the drying air, the viscosity μ of the drying air, the viscosity μ of the drying air, and the average flow velocity v.

Evaluation Each sample No. Samples were taken from the beginning 5 m and end 5 m from 501 to 512, the film thickness stability was measured by the same method as in Example 1, and the results of evaluation with the same evaluation rank as in Example 1 are shown in Table 5. Show.

  It was confirmed that the film thickness stability was excellent when the Reynolds number (Re) of the drying air in the laminar flow state was 73 to 1950 and the average flow velocity was 0.3 m / sec or more. The effectiveness of the present invention was confirmed.

Example 6
A band-shaped organic EL element structure (flexible substrate / first electrode (anode) / hole transport layer / light emitting layer / electron transport layer / second electrode (cathode)) is used in the manufacturing process shown in FIG. The amount of the solvent contained in the light-emitting layer-forming coating film after passing through the preliminary drying step was changed as shown in Table 7, and after preparing by the method shown below, cutting was performed to prepare an organic EL element and a sample. No. 601 to 608. The hole transport layer, the light emitting layer, and the electron transport layer were formed by coating with a slit type die coater, and the first electrode (anode) and the second electrode (cathode) were formed by vapor deposition.

<Preparation of strip-shaped substrate>
A polyethylene terephthalate film (Teijin-DuPont film, hereinafter abbreviated as PET) having a thickness of 100 μm, a width of 200 mm, and a length of 500 m was prepared as a belt-like substrate. In addition, in order to show the position which forms a 1st electrode in the strip | belt-shaped base material previously, the alignment mark was provided in the same position of the surface in which a 1st electrode is formed, and the opposite surface.

<Formation of the first electrode>
On the prepared belt-like substrate, ITO (indium tin oxide) having a thickness of 120 nm is formed by a sputtering method under a vacuum environment condition of 5 × 10 ⁻¹ Pa by a sputtering method, and a size of 12 mm × 5 mm having an extraction electrode. The first electrode was continuously formed in 12 rows at regular intervals, and was wound up and stored once.

(Preparation of coating solution for hole transport layer formation)
A solution prepared by diluting polyethylene dioxythiophene / polystyrene sulfonate (PEDOT / PSS, Baytron P AI 4083 manufactured by Bayer) with pure water at 65% and methanol at 5% was prepared as a coating solution for forming a hole transport layer. The viscosity of the coating liquid for forming a hole transport layer was 0.7 mPa · s. The viscosity is a value measured at 20 ° C. using a digital viscometer LVDV-I manufactured by Brookfield.

(Formation of hole transport layer)
Using the prepared slit type die coater, the roll-shaped PET on which the prepared first electrode is formed is subjected to charge removal treatment, and then the entire upper surface of the first electrode of the PET held on the backup roll (however, at both ends) The prepared coating liquid for forming a hole transport layer was applied under the following conditions, followed by drying and heat treatment.

(Charge removal treatment)
For the charge removal treatment, a non-contact type antistatic device was used on the first electrode formation side, and a contact type antistatic device was used on the back side. As the non-contact type antistatic device, a flexible AC ionizing bar MODEL4100V manufactured by Hugle Electronics Co., Ltd. was used. The contact-type antistatic device was a conductive guide roll ME-102 manufactured by Miyako Roller Industry Co., Ltd.

(Application conditions of the coating liquid for forming the hole transport layer)
As coating conditions, the coating liquid for forming the hole transport layer was applied at a coating speed of 5 m / min, the coating width was 180 mm, the wet film thickness was 2 μm, the temperature during coating of the coating liquid for forming the hole transport layer was 25 ° C., and the dew point temperature − It was carried out under an atmospheric pressure of N ₂ gas environment of 20 ° C. or less and with a cleanliness class 5 or less (JIS B 9920). The amount of solvent contained in the coating film for hole transport layer formation after passing through the preliminary drying step was 5% by mass with respect to the amount of solvent contained in the coating liquid for hole transport layer formation.

  A back roll having a diameter of 300 mm was used.

Predrying process conditions Temperature of drying air flowing through the drying chamber: 25 ° C
Average wind speed of the drying air flowing through the drying chamber: 1.0 m / sec
Height from the back roll surface at the entrance of the drying chamber: 5 mm
Height from the back roll surface at the exit of the drying chamber: 5 mm
Distance from entrance to exit of drying chamber: 200mm
Surface roughness (Ra) of the inner surface of the drying chamber: 5 μm
Ratio (%) to coating width of coating liquid for forming organic thin film layer in drying chamber: 150%
The direction in which the drying air flows was the same as the transport direction of the belt-shaped substrate.

  The wet film thickness indicates a theoretical value calculated by a flow rate (supply amount) / (application width × application speed).

  The coating speed was measured with a laser Doppler velocimeter LV203 manufactured by Mitsubishi Electric Corporation.

Drying and Heating Treatment Conditions Drying and heating treatment conditions for the coating film for forming the hole transport layer are as follows. After applying the coating liquid for forming the hole transport layer and passing through the preliminary drying process, using the drying device, After removing the residual solvent by blowing hot air with a slit nozzle type outlet from the outlet to a height of 100 mm, an outlet air velocity of 1 m / sec, a wide air velocity distribution of 5%, and a temperature of 120 ° C. A back surface heat transfer type heat treatment was performed at a temperature of 150 ° C. to form a hole transport layer. The dry film thickness (film thickness after drying) was 100 nm.

(Preparation of light emitting layer forming coating solution)
Dicarbazole derivative (CBP) 1.00% by mass
Iridium complex (Ir (ppy) ₃ ) 0.05% by mass
Toluene 98.95% by mass
The viscosity of the light emitting layer forming coating solution was 0.59 mPa · s. The viscosity is a value measured at 20 ° C. using a Brookfield Digital Viscometer LVDV-I.

(Formation of light emitting layer)
After the roll-shaped PET formed up to the prepared hole transport layer is charged and removed, the prepared slit die coater is applied to the entire upper surface of the hole transport layer (except 10 mm at both ends of the PET). The light emitting layer forming coating solution was applied under the conditions shown below. After coating, the amount of solvent contained in the coating film for forming the light-emitting layer after passing through the preliminary drying step and passing through the preliminary drying step is changed as shown in Table 5, and subsequently in the drying section according to the conditions shown below. Subsequently, it was transported to the electron transport layer forming step after drying and heat treatment. The amount of solvent contained in the light emitting layer forming coating film after passing through the preliminary drying step indicates a ratio (% by mass) to the amount of solvent contained in the light emitting layer forming coating solution. The change in the amount of the solvent contained in the light-emitting layer-forming coating film after passing through the preliminary drying step is to change the average flow rate of the drying air flowing through the drying air channel from 0.08 m / sec to 2.5 m / sec. I went there.

  For the charge removal treatment, a non-contact type antistatic device was used for the light emitting layer side, and a contact type antistatic device was used for the back surface side. The non-contact type antistatic device and the tactile type antistatic device were the same as those used for forming the hole transport layer.

(Application conditions of the light emitting layer forming coating solution)
As the coating conditions, the light emitting layer forming coating solution is applied at a coating speed of 5 m / min, the coating width is 180 mm, the wet film thickness is 3 μm, the temperature at the time of coating the light emitting layer forming coating solution is 25 ° C., and the dew point temperature is −20 ° C. or lower. The test was performed under atmospheric pressure in a N ₂ gas environment and with a cleanliness class of 5 or less (JIS B 9920). The coating speed was measured by the same measuring method as the coating speed of the hole transport layer.

Pre-drying process conditions The conditions were the same as those for forming the hole transport layer except for the average flow velocity of the drying air flowing through the drying air channel.

  The amount of solvent contained in the light-emitting layer-forming coating film when transported in the pre-drying process is adjusted by adjusting the transport speed of the belt-shaped substrate and the distance between the slit die coater and the opening of the pre-drying device. It was 90 mass% with respect to the amount of solvent contained in the coating liquid for layer formation.

Drying and heat treatment conditions Drying and heat treatment conditions for the coating film for forming the light emitting layer include applying a coating liquid for forming the light emitting layer, and then using a drying device. The drying condition is a slit nozzle type outlet of the drying device. After removing the solvent at a height of 100 mm toward the film-forming surface, an outflow air velocity of 1 m / sec, a wide air velocity distribution of 5%, and a temperature of 120 ° C., the heat treatment is then performed at the temperature of 150 ° C. using a heat treatment device. To form a light emitting layer. The dry film thickness (film thickness after drying) was 100 nm.

(Preparation of coating solution for electron transport layer formation)
As a coating liquid for forming an electron transport layer, a 1-butanol solution containing 0.5% by mass of the electron transport material 1 was prepared.

(Formation of electron transport layer)
After the roll-shaped PET formed up to the prepared light emitting layer is charged and removed, the prepared slit type die coater is used on the entire upper surface of the light emitting layer (excluding 10 mm at both ends of the PET). The applied electron transport layer forming coating solution was applied under the following conditions. After coating, after drying and heat treatment in the drying section under the conditions shown below, the hole transport layer, light emitting layer and electron transport layer formed on the extraction electrode section of the first electrode are removed and patterned. The PET having the electron transport layer formed thereon was prepared and temporarily wound and stored.

(Charge removal treatment)
For the charge removal treatment, a non-contact type antistatic device was used on the electron transport layer side, and a contact type antistatic device was used on the back side. The non-contact type antistatic device and the tactile type antistatic device were the same as those used for forming the hole transport layer.

(Coating conditions for the electron transport layer forming coating solution)
As the coating conditions, the coating solution for forming the electron transport layer was coated at a coating speed of 5 m / min, the coating width was 180 mm, the wet film thickness was 2 μm, the temperature at the coating of the coating solution for forming the electron transport layer was 25 ° C., and the dew point temperature was −20. It was carried out under an atmospheric pressure of N ₂ gas environment of not more than 0 ° C. and with a cleanliness class of 5 or less (JIS B 9920). The coating speed was measured by the same measuring method as the coating speed of the hole transport layer.

Pre-drying process conditions The conditions were the same as when forming the hole transport layer, including the average flow velocity of the drying air flowing through the drying air flow path.

  The wet film thickness indicates a theoretical value calculated by a flow rate (supply amount) / (application width × application speed).

  The coating speed was measured with a laser Doppler velocimeter LV203 manufactured by Mitsubishi Electric Corporation.

Drying and heat treatment conditions The drying and heat treatment conditions for the coating film for forming the electron transport layer are as follows. After the coating liquid for forming the electron transport layer is applied, a drying apparatus is used. After removing the solvent from the outlet to the film formation surface at a height of 100 mm, outflow air velocity of 1 m / sec, wide air velocity distribution of 5%, and a temperature of 120 ° C, the backside heat transfer system at a temperature of 150 ° C by a heat treatment device. The electron transport layer was formed by performing the heat treatment. The dry film thickness (film thickness after drying) was 50 nm.

(Formation of second electrode)
Subsequently, the alignment mark attached to the PET formed up to the electron transport layer is detected, and the size of the first electrode and the extraction electrode for the second electrode are formed on the electron transport layer formed according to the position of the alignment mark. In a vacuum of 5 × 10 ⁻⁴ Pa, aluminum is used as a second electrode forming material, a mask pattern is formed by vapor deposition, and a second electrode having a thickness of 100 nm is stacked to form a plurality of organic layers. An organic EL element structure in which an EL element was formed was produced.

(Cutting)
In the state in which a plurality of prepared organic EL elements are continuously connected, the alignment mark attached to the PET is detected to the size of the individual organic EL element, and the individual organic EL elements are cut by cutting according to the position of the alignment mark. Produced.

Preparation of a comparative sample An organic thin film layer was formed under the same conditions except that the hole transport layer, the light emitting layer, and the electron transport layer were dried at a temperature of 150 ° C in the main drying process without using the preliminary drying process, and an organic thin film layer was formed. . 609.

Evaluation The produced sample No. From 601 to 609, samples prepared from locations of 5 m at the beginning and 5 m at the end were extracted, and leakage current characteristics and luminance unevenness were tested by the test methods shown below, and the results of evaluation according to the evaluation rank shown below are shown in Table 6. Shown in

Test Method for Leakage Current Characteristics Using a constant voltage power source, a reverse voltage (reverse bias) was applied at 5 V for 5 seconds, and the current flowing through the organic EL element at that time was measured. Measurement was performed on the light emission region of 10 samples, and the maximum current value was defined as a leakage current.

Evaluation rank of leakage current characteristics A: Maximum current value is less than 1 × 10 ⁻⁶ A ○: Maximum current value is 1 × 10 ⁻⁶ A or more and less than 1 × 10 ⁻⁵ A Δ: Maximum current value is 1 × 10 ^{− 5} A or more, less than 1 × 10 ⁻³ A ×: The maximum current value is 1 × 10 ⁻³ A or more.

Measuring method of light emission unevenness (brightness unevenness) Using a constant voltage power source, DC 5 V was applied to the organic EL panel, and the luminance difference of 6 light emitting portions in the center of the sample was visually observed.

Evaluation rank of light emission unevenness (brightness unevenness) ◎: No difference in brightness ○: Brightness at one place is different among six places Δ: Brightness at two or more and less than four places is different among six places ×: Among six places The brightness at four or more locations is different.

  An organic EL device having a layer structure of the prepared flexible substrate / first electrode (anode) / hole transport layer / light emitting layer / electron transport layer / second electrode (cathode) under the predrying conditions of the present invention Sample No. It was confirmed that all of 602 to 607 showed stable performance in terms of leakage current characteristics and luminance unevenness.

  An organic EL device produced under conditions other than the predrying conditions of the present invention (the amount of solvent contained in the coating film after passing through the predrying step is 0.007% by mass with respect to the amount of solvent contained in the coating solution) Sample No. Sample No. 601 shows both leakage current characteristics and luminance unevenness. Inferior results from 602 to 607.

  Organic EL device produced under conditions other than pre-drying conditions of the present invention (the amount of solvent contained in the coating film after passing through the pre-drying step is 7.0% by mass with respect to the amount of solvent contained in the coating solution) Sample No. Sample No. 608 has both leakage current characteristics and uneven brightness. Inferior results from 602 to 607.

  Sample No. which is an organic EL device produced without pre-drying. Sample No. 609 is a sample No. for both leakage current characteristics and uneven luminance. Inferior results from 602 to 607.

  The effectiveness of the present invention was confirmed.

DESCRIPTION OF SYMBOLS 1 Manufacturing process 102 Hole transport layer formation process 103 Light emitting layer formation process 104 Electron transport layer formation process 107 2nd electrode formation process 2, 2a, 5 Band-shaped base material 4 Formation process 4b Application | coating process 102a1, 103a1, 104a1, 4b1 Wet application Machine 102b1, 103b1, 104b1, 4c Pre-drying step 4c1 Drying device 4c11 Drying chamber 4c115, 4c116 Opening 4c12 Pressure control unit 102b2, 103b2, 103b2, 4d Drying step 102b21, 103b21, 104b21, 4d1 Drying device

Claims (7)

Formation of an organic thin film layer having a coating step of applying a coating liquid for forming an organic thin film layer on a belt-like substrate supported and transported by a back roll, and a drying step of drying the coating film formed in the coating step In the method
The drying step uses a drying device having a drying chamber on the back roll ,
The height from the surface of the back roll of the drying chamber is set to continuously change within a range of 0.1 mm to 50 mm from the entrance to the exit of the drying chamber,
In the drying step, the coating film is dried by a laminar drying air formed by a suction method,
The method for forming an organic thin film layer, wherein the laminar dry air is flowing in the same direction as the transport direction in parallel to the length direction of the belt-like substrate . The method for forming an organic thin film layer according to claim 1, wherein the drying chamber is depressurized. The position where the coating film is transported into the drying chamber while the amount of solvent contained in the coating film is 20% or more with respect to the amount of solvent contained in the coating liquid for forming an organic thin film layer in the drying step. The method for forming an organic thin film layer according to claim 1 , wherein the organic thin film layer is disposed. Claim wherein the drying step, characterized in that the amount of solvent contained in the coating film, 10.0 wt% 0.01 wt% of the solvent amount contained in the organic thin film layer forming coating solution 4. The method for forming an organic thin film layer according to any one of 1 to 3 . The Reynolds number (Re) of the dry air is 70 to 1950, and the average flow velocity is 0.3 m / sec or more. The organic thin film layer formation according to any one of claims 1 to 4, Method. Temperature of the drying air of the laminar flow state, claim 1, wherein said organic thin film layer forming coating liquid, a ± 5 ℃ relative ambient temperature when applied on the strip-like base material 6. The method for forming an organic thin film layer according to any one of items 1 to 5 . In the manufacturing method of the organic electroluminescent element which has an at least 1st electrode, an at least 1 layer of organic layer, and a 2nd electrode on a base material, the said organic layer is an organic thin film of any one of Claim 1 to 6 It is formed by the formation method of a layer. The manufacturing method of the organic electroluminescent element characterized by the above-mentioned.