JP2013250002A - Drying device and drying method for coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a distance between a condensation surface of a condensation plate and a coating film surface on a substrate to be held at a constant value, with high accuracy in an entire drying process, and to equalize a drying speed in a coating film surface, thereby improving uniformity of drying.SOLUTION: A drying device 1A has a condensation plate 11 faced to a coating film on a substrate f1, and condenses vapor of a solvent from the coating film by the condensation plate 11, for drying. The drying device 1 has a clearance holding roller 15a for holding a distance between a condensation surface 11a of the condensation plate 11 and a coating film surface f2a on the substrate f1 at a constant value.

Description

  The present invention relates to a coating film drying apparatus and a drying method.

  As a method for forming an organic thin film in an organic electroluminescence (EL) element or an organic thin film solar cell, a vacuum process is not required and continuous production is easy. Attention has been focused on application methods by wet processes such as spraying and printing. However, according to the wet process, drying unevenness may occur in the step of drying the coating film, and it is difficult to obtain a uniform film thickness. One of the factors is that a highly volatile organic solvent is used as a solvent for the coating solution in order to increase the solubility.

  Conventionally, as a drying method capable of uniform drying, a drying method in which a condensing plate faces a coating film surface and a solvent in the coating film is condensed by the condensing plate has been disclosed (for example, see Patent Document 1). According to this drying method, precise drying is possible by controlling the distance between the condenser plate and the coating film and the respective surface temperatures without using convection.

  In order to increase the drying speed while maintaining uniform drying, the distance between the condenser plate and the coating film may be reduced. However, when drying a long substrate, the distance accuracy is maintained throughout the drying process. There is a need. Unevenness of drying often occurs immediately after coating, and drying at the initial stage greatly contributes to the uniformity of drying.Therefore, the distance between the condenser plate and the coating film is reduced only in the initial stage of drying immediately after coating. A holding drying method has been proposed (see, for example, Patent Document 2).

Special table 2003-524847 JP 2011-25244 A

  However, according to Patent Document 2, the distance between the condensing plate and the coating film varies depending on the position in the transport direction, so that the uniformity of drying is not sufficient. In order to obtain the uniformity of the film thickness necessary for the electronic devices such as organic EL elements to perform their functions well, the distance between the condenser plate and the coating film is maintained with higher accuracy and the drying uniformity is further improved. It is demanded to make it.

  An object of the present invention is to improve the uniformity of drying of a coating film.

According to the invention of claim 1,
In a drying apparatus comprising a condensing plate facing the coating film on the substrate, condensing the solvent vapor from the coating film with the condensing plate, and drying,
There is provided a coating film drying apparatus comprising a gap holding means for holding a distance between a condensation surface of the condenser plate and a coating film surface on the substrate at a constant value.

According to invention of Claim 2,
The coating film drying apparatus according to claim 1, wherein the gap holding means is a gap holding roller that is disposed between the substrate and the condenser plate to support and convey the condenser plate.

According to invention of Claim 3,
The coating film drying apparatus according to claim 1, wherein the gap holding means is a gap holding tape disposed between the substrate and the condenser plate.

According to invention of Claim 4,
The coating film drying apparatus according to claim 3, wherein a height of the gap holding tape is in a range of 0.1 to 4.0 mm.

According to the invention of claim 5,
The said condensing plate is provided with the drying apparatus of the coating film as described in any one of Claims 1-4 containing the absorber of a solvent.

According to the invention of claim 6,
In the drying method of the coating film, the condenser plate facing the coating film on the substrate is arranged, the vapor of the solvent from the coating film is condensed by the condensation plate, and dried.
Provided is a coating film drying method in which a gap holding means is disposed between the condenser plate and the substrate, and the distance between the condensation surface of the condenser plate and the coating film surface on the substrate is maintained at a constant value by the gap holding means. Is done.

  According to the present invention, the distance between the condensing surface of the condensing plate and the coating film surface on the substrate can be maintained at a constant value with high accuracy in the entire drying process, and the drying speed in the coating film surface is kept constant. Can improve the uniformity.

The example of the production line where the drying apparatus of the coating film which concerns on this Embodiment was used is shown. It is the front view of the drying apparatus of FIG. 1 seen from the conveyance direction of the board | substrate. The example of the drying device concerning other embodiments is shown. FIG. 4 is a front view of the drying device of FIG. 3 as viewed from the substrate transport direction. It is a top view of the gap holding tape located at both ends of the substrate. It is a top view of the gap holding tape located in the both ends and center of a board | substrate. It is the upper side figure which expanded the gap maintenance tape which has a convex part. It is sectional drawing of the convex part of FIG.

  Embodiments of a coating film drying apparatus and drying method of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a production line in which a coating film drying apparatus 1A according to the present embodiment is used.
In the production line shown in FIG. 1, an organic layer coating solution is applied by a coating device 3 onto a substrate f1 held and transported by rollers 22 and 23, and the coating film is dried by a drying device 1A.
In addition, you may install the drying apparatus for post-processing after the drying apparatus 1A for the purpose of the removal of a residual solvent, etc. The drying method is not particularly limited. For example, solid heat transfer drying such as hot air, infrared rays and plane heating, internal heat generation drying using microwaves, vacuum drying, supercritical drying, ultrasonic drying, etc. Known methods such as gas drying such as system drying, moisture absorption drying, cooling drying, and condensation drying can be selected.

The substrate f1 is a coating object. As the substrate f1, a base material made of a flexible material such as a metal, a glass substrate or a resin film, or a base material support when the base material itself is coated is used. Some organic layers may already be formed on the substrate f1.
The substrate f1 is sent out to the coating device 3 by the unwinder 21 and wound by the winder 24 after coating and drying.

  In addition to wet processes such as spin coating, casting, ink-jet, spraying, and printing, the coating apparatus 3 is a slot method using a slit-type die coater, an ESD (Electro Spray Deposition) method, ESDUS. Apply the coating solution by the Evaporative Spray Deposition from Ultra-ditule Solution method. If the coating liquid containing a solvent can be apply | coated, the coating method of the coating device 3 will not be specifically limited.

  As a method of coating on the substrate f1 that is continuously transported, a post-weighing type in which an application liquid is applied in excess of the amount necessary to form a coating film having a required film thickness, and then the excess is removed. A pre-weighing type in which a coating solution is applied in a necessary amount is known. Any coating method can be applied, but the pre-weighing type is preferable from the viewpoints of high accuracy of coating, high speed, thin film, improved coating film quality, suitability for lamination, and the like. Moreover, a closed system is preferable from the viewpoints of suppressing the exposure of the coating liquid, suppressing the change in concentration, maintaining the cleanliness, and preventing the contamination of foreign matters. Therefore, among the above coating methods, a slot method using a slit type die coater, a spray method, and an ink jet method are preferable.

The coating solution can be prepared by dissolving or dispersing an organic material in a solvent.
In the case of an organic EL device in which organic layers such as a hole transport layer, a light-emitting layer, and an electron transport layer are sequentially stacked between an anode and a cathode, examples of organic materials for the hole transport layer include triazole derivatives, oxazole derivatives, and oxazines. Azole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline-based co-weights Examples thereof include conductive polymer oligomers such as coalescence and thiophene oligomers.

The organic material for the light emitting layer may be a low molecular compound having no repeating unit, a high molecular compound having a repeating unit, or a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group.
Specifically, compounds having a basic skeleton such as carbazole derivatives, triarylamine derivatives, aromatic borane derivatives, nitrogen-containing heterocyclic compounds, thiophene derivatives, furan derivatives, oligoarylene compounds, and carboline derivatives as organic materials for the light-emitting layer And diazacarbazole derivatives (herein, diazacarbazole derivatives are derivatives in which at least one carbon atom of the hydrocarbon ring constituting the carboline ring of the carboline derivative is substituted with a nitrogen atom).
Moreover, a phosphorescent compound is also mentioned as an organic material of a light emitting layer. The phosphorescent compound is a complex compound containing a group 8 to group 10 metal in the periodic table of elements, and examples thereof include iridium compounds, osmium compounds, platinum compounds, and rare earth complexes.

  Examples of the organic material for the electron transport layer include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane, anthrone derivatives, oxadiazole derivatives, and the like.

  In addition to the organic EL element, the coating apparatus 3 can form organic layers such as a solar cell, a transistor, a memory, and a sensor. Examples of such an organic material include conductive polymers such as polythiophene, pentacene, naphthalene derivatives, and the like.

  The solvent used in the coating solution depends on the organic material that is a solute. For example, pure water, alcohols such as 2-ethoxyethanol and 2-methoxyethanol, and halogens such as chloroform, methylene chloride, tetrachloroethylene, dichloroethane, and tetrahydrofuran , Aromatic hydrocarbons such as xylene, toluene, hexane, cyclohexylbenzene, and anisole, ketones such as acetone and methyl ethyl ketone, esters such as acetic acid, methyl acetate, ethyl acetate, butyl acetate, and acetonitrile, diethyl ether, dimethyl And sulfoskid.

Depending on the purpose of controlling the application range and the purpose of controlling the liquid flow accompanying the surface tension gradient after application (for example, the liquid flow causing a phenomenon called coffee ring) A solvent can be contained.
Examples of the surfactant include an anionic or nonionic surfactant from the viewpoint of the influence of moisture contained in the solvent, leveling properties, wettability to the substrate f1, and the like. Specifically, surfactants listed in International Publication No. 08/146661, JP-A-2-41308, etc., such as fluorine-containing activator, can be used.

The thickness of the coating film can be appropriately selected depending on the function required for the organic layer and the solubility or dispersibility of the organic material. As the film thickness increases, drying unevenness due to flow tends to occur, and the usefulness of the drying apparatus 1A capable of uniform drying is great.
Specifically, the thickness of the coating film is preferably in the range of 1 to 90 μm.

Similarly to the film thickness, the viscosity of the coating film can be appropriately selected depending on the function required for the organic layer and the solubility or dispersibility of the organic material. As the viscosity is smaller, drying unevenness due to flow tends to occur, and the usefulness of the drying apparatus 1A capable of uniform drying is great.
Specifically, the viscosity of the coating film is preferably in the range of 0.3 to 100 mPa · s, and more preferably in the range of 0.5 to 10 mPa · s.

[Drying equipment]
FIG. 2 is a front view of the inside of the drying apparatus 1A as viewed from the conveyance direction y of the substrate f1.
As shown in FIGS. 1 and 2, the drying apparatus 1A includes a condensing plate 11 facing the coating film f2 on the substrate f1, and the condensing plate 11 condenses the vapor of the solvent contained in the coating film f2 on the substrate f1. Then, the coating film f2 is dried.

  The drying device 1A is preferably installed immediately after the coating device 3 so that it can be dried immediately after the coating film. During the period from the coating to drying, there is an influence of the surrounding airflow and natural convection generated in the drying apparatus 1A. However, by starting drying immediately after the coating, drying unevenness due to the influence of the airflow can be prevented. Although it depends on the conveyance speed, the time from the coating film to drying is preferably within 30 seconds, and more preferably within 10 seconds. In addition, between the coating device 3 and the drying device 1A, a blocking plate can be provided as a surrounding air flow blocking means, and a rectifying plate as a surrounding air flow rectifying means so that no air flow is generated on the coating film f2. And a fan for rectification can be provided.

The drying apparatus 1 </ b> A transports the substrate f <b> 1 by a plurality of rollers 131.
In addition, the drying apparatus 1A conveys the sheet-shaped condensing plate 11 with a plurality of rollers 132 while facing the coating film f2 on the substrate f1. Although the condensing plate 11 is sent out by the unwinder 141 and wound up by the winder 142, the condensing plate 11 may be wound around the roller 132 and repeatedly used.

The drying apparatus 1A includes a heating device 12 that is disposed to face the substrate f1.
The heating device 12 heats the coating film f2 through the substrate f1 and promotes evaporation of the solvent. The heating method is not particularly limited, and examples thereof include heating methods such as heating by hot air (heating gas), infrared rays, UV, and plane heating, and internal heating using electric resistance by microwaves.

  The material of the condensing plate 11 is not particularly limited, but the condensing plate 11 preferably contains a solvent absorber. By containing the absorbent, the condensing plate 11 absorbs the solvent condensed on the condensing surface 11a, the solvent can be discharged from the condensing surface 11a, and further condensation of the solvent can be promoted. The condensing surface 11a refers to the surface of the condensing plate 11 that faces the coating film surface f2a and condenses the solvent from the coating film f2. The coating film surface f2a is the surface of the coating film f2.

  Examples of such absorbent materials include porous materials, high silica zeolite, activated carbon, and the like. Further, the condensing plate 11 can be configured by bonding a sheet made of an absorbent material to a resin film or the like. For example, a solvent absorbing material described in JP-A-2005-232308, a resin film including a solvent-absorbing layer described in JP-A-2003-191598, and the like can be used as the condensing plate 11.

Moreover, it is preferable to use a material having a large heat capacity as the condensing plate 11 from the viewpoint of preventing the condensation from slowing down. In order to condense the solvent, it is necessary to maintain the condensing surface 11a at a lower temperature than the coating film surface f2a. By using the condensing plate 11 having a large heat capacity, even when radiant heat is generated from the coating film f2 by the heating of the heating device 12, the temperature rise of the condensing surface 11a due to the radiant heat can be suppressed, and the slowing of condensation can be prevented. .
Specifically, the heat capacity is preferably 2700 kJ / m ³ · K or more, and the larger the better.

  Examples of the material having such a heat capacity include zirconia, cast iron, alumina, and the like, and can be appropriately selected in consideration of workability and thermal conductivity. In particular, the condenser plate 11 is required to have a certain degree of thermal conductivity from the ease of temperature control, and the higher the thermal conductivity, the easier it is to shift the temperature of the condenser plate 11 to a steady state at a desired temperature.

The condensing plate 11 can have a plurality of slits in the condensing surface 11a in order to discharge the condensed solvent from the condensing surface 11a and promote further condensation. The extending direction of the slit may be either the width direction x or the conveyance direction y. The solvent condensed on the condensing surface 11a by the capillary force of the slit is transported to the end in the width direction x or the transport direction y and discharged.
When the slit is provided, a side plate hanging from the side surface of the condensing plate 11 or a container for collecting the solvent may be provided, and the solvent discharged to the end along the slit may be collected by the side plate.

The condensing plate 11 may be subjected to a surface treatment on the condensing surface 11a.
For example, the condensation surface 11a can be subjected to a water repellent treatment or a hydrophilic treatment in order to prevent contamination or to efficiently discharge the condensed solvent.
As the water repellent treatment, as described in JP-A-2005-343016 and JP-A-2000-254582, a water-repellent material such as a silane compound having a fluoroalkyl group, an alkyl group or the like is used as a flow coating method. And a treatment applied by a dip coating method or the like. In addition, as described in JP-A-2005-23122, a honeycomb structure or pillar structure film manufactured using a polymer having a polyfluoroalkyl group having water and oil repellency is applied to the condensation surface. May be.

Examples of other surface treatment include rubbing treatment to prevent drying unevenness. Moreover, in order to improve wettability, the condensation surface 11a can also be finished rough.
In addition, the solvent on the condensation surface 11a may be discharged by a mechanical force such as a belt, a wipe, or a pump.

The drying speed of the drying apparatus 1A can be controlled by adjusting the temperature Tc of the condensing surface 11a and the temperature Th (Th> Tc) of the coating film surface f2a.
The temperature control method of the condenser plate 11 is not particularly limited, but considering that it is in the form of a sheet, heating or cooling by blowing may cause contact with the coating film f2. Therefore, it is preferable that the condenser plate 11 is cooled in advance with a refrigerant, or the temperature Tc of the condensing surface 11a is set to room temperature and the temperature Th of the coating film surface f2a is set to room temperature or higher.
If necessary, a cooling device can be used together with the heating device 12 to control the temperature Th of the coating film surface f2a.

  The temperature Tc of the condensing surface 11a may be higher or lower than room temperature as long as it is lower than the temperature Th of the coating film surface f2a, but is preferably in the range of 5 to 30 ° C, and in the range of 10 to 20 ° C. It is more preferable that By controlling within the above range, an increase in cost required for heating can be suppressed. Further, uniform temperature control of the entire condensing surface 11a is facilitated, and drying unevenness due to temperature unevenness, and thus film thickness unevenness of the coating film f2 can be easily suppressed. From the same viewpoint, the temperature unevenness in the condensing surface 11a is preferably within 2 ° C.

In order to prevent substances other than the solvent such as moisture in the atmosphere from condensing on the condensation surface 11a, it is preferable to lower the dew point of the atmosphere or reduce the pressure between the condensation surface 11a and the coating film surface f2a.
Further, in order to prevent the solvent from condensing on the members of the drying apparatus 1A other than the condensing plate 11, such as the housing, the rollers 131, 132, etc., the temperature of the members other than the condensing plate 11 is set to be equal to or higher than the temperature Tc of the condensing surface 11a. It is preferable to adjust.

  The temperature Th of the coating film surface f2a may be higher or lower than room temperature as long as it is higher than the temperature Tc of the condensing surface 11a, but is preferably within a range of 30 to 100 ° C, and within a range of 30 to 70 ° C. It is more preferable that By setting it as 30 degreeC or more, it is easy to suppress that the water | moisture content etc. in air | atmosphere other than a solvent condense, and drying efficiency falls. By setting the temperature to 100 ° C. or lower, it is easy to suppress an increase in cost due to a high temperature and a conveyance failure due to the modification of the substrate f1. In addition, uniform temperature control of the entire substrate f1 is facilitated, and drying unevenness due to temperature unevenness, and consequently film thickness unevenness of the coating film f2, can be easily suppressed. From the same viewpoint, the temperature unevenness in the coating film surface f2a is preferably within 2 ° C.

  The drying speed of the drying apparatus 1A can also be controlled by adjusting the distance d between the condensation surface 11a and the coating film surface f2a. As the distance d is smaller, the solvent is more easily condensed and the drying speed is increased, but is preferably in the range of 0.1 to 10 mm, and more preferably in the range of 0.1 to 4 mm. By setting the thickness to 0.1 mm or more, it is easy to avoid contact between the coating film f2 and the condensing plate 11 due to flapping of the substrate f1, and it is possible to reduce the cost associated with high accuracy of the arrangement of the condensing plate 11. Moreover, it is easy to avoid adhesion of the condensed solvent to the coating film f2, and drying unevenness due to adhesion can be suppressed. Moreover, by being within 10 mm, the influence of the surrounding convection can be reduced, drying unevenness can be prevented, the drying speed can be increased, and productivity can be improved.

By keeping the distance d between the condensing surface 11a and the coating film surface f2a at a constant value, the drying speed in the coating film surface f2a can be made constant, and the uniformity of drying can be improved.
The drying apparatus 1A includes a gap holding roller 15a disposed between the condensing plate 11 and the substrate f1, and the gap holding roller 15a supports and conveys the condensing plate 11 from the lower portion, so that the distance d is constant throughout the drying process. Held in value.

  Unevenness of drying often occurs immediately after application where the viscosity of the coating film f2 is low, and the drying at the initial stage contributes to uniform drying. Therefore, the gap holding roller 15a positioned immediately after application can be replaced with a belt having a certain length in the transport direction y, and the distance d can be more reliably held at a constant value in the initial stage.

[Other Embodiments of Drying Apparatus]
FIG. 3 shows a drying apparatus 1B according to another embodiment. FIG. 4 is a front view of the inside of the drying apparatus 1B as viewed from the conveyance direction y.
As shown in FIGS. 3 and 4, the drying apparatus 1B includes a gap holding tape 15b disposed between the condensing plate 11 and the substrate f1, as shown in FIGS. 3 and 4. The condensing surface 11a and the coating film surface are provided by the gap holding tape 15b. The distance d between f2a is held at a constant value. By interposing the gap holding tape 15b, the airflow entering between the condenser plate 11 and the coating film f2 can be blocked, and the influence of the outside wind can be reduced.

  The drying apparatus 1 </ b> B transports the gap holding tape 15 b with a plurality of rollers 133. The gap holding tape 15b may or may not contact the substrate f1 and the condenser plate 11. Even in the case of contact, the gap corresponding to the height h of the gap holding tape 15b can be held. The gap holding tape 15 b is sent out by the unwinder 143 and wound up by the winder 144. Note that the gap holding tape 15b may be wound around the roller 133 and used repeatedly.

  The height h of the gap holding tape 15b can be set according to the distance d to be held. If the film thickness of the coating film f2 is smaller than the distance d and can be regarded as h≈d, the height h is within a range of 0.1 to 10 mm corresponding to a preferable range of the distance d. Is preferable, and it is more preferable to be within a range of 0.1 to 4 mm.

FIG. 5 is a top view of the substrate f1 viewed from the condenser plate 11 side.
As shown in FIGS. 4 and 5, the gap holding tape 15b is disposed at positions corresponding to both ends of the coating film f2 in the width direction x. When the coating film f2 is long in the width direction x and the substrate f1 or the condensing plate 11 sag near the center in the width direction x, the gap holding tape 15b may be disposed in the center as shown in FIG. it can.

The gap holding tape 15b may be a flat tape or may have irregularities on the surface. The material of the gap holding tape 15b can be reduced by the unevenness, and the cost can be reduced. In addition, the height h can be easily adjusted by changing the addition amount and concentration of the material forming the unevenness.
For example, as the gap holding tape 15b, a tape having a convex object can be used as described in JP 2011-49084 A.

7 is an enlarged top view of the gap holding tape 15b having the convex portion 151 on the surface, and FIG. 8 is a cross-sectional view of the convex portion 151 taken along the line QQ in FIG.
The dome-shaped convex portion 151 as shown in FIG. 8 can be formed by embossing or the like, or can be formed by dropping an ultraviolet curing agent or the like and irradiating it with ultraviolet rays to be cured.
In addition, when it has the convex part 151, it is preferable that the height h including the convex part 151 is in the above-mentioned range, as shown in FIG.

[Drying method]
As shown in FIG. 1 and FIG. 2 or FIG. 3 and FIG. 4, the drying method of the coating film according to the present embodiment places the condensing plate 11 on the coating film f2 on the substrate f1, and arranges the coating film. The solvent vapor from f2 is condensed on the condensing surface 11a and dried. During drying, a gap holding roller 15a or a gap holding tape 15b is disposed as a gap holding means between the condenser plate 11 and the substrate f1, and the distance d between the condensation surface 11a and the coating film surface f2a is set by the gap holding roller 15a or the gap holding tape 15b. Is held at a constant value.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these.

[Preparation of gap holding roller]
Using SUS304, a gap holding roller having a width of 0.04 m and a roll diameter of 0.01 m was produced.

[Preparation of gap holding tape E1]
10 mm square embossing is performed on a polyethylene naphthalate film (manufactured by Teijin DuPont, hereinafter referred to as PEN film) having a length of 0.04 m in the width direction, a length of 40 m in the conveyance direction, and a thickness of 0.10 mm. A gap holding tape E1 having a height h of 2.00 mm was produced.

[Preparation of gap holding tape E2]
Using a piezo-type ink jet head on a PEN film (manufactured by Teijin DuPont) with a length of 0.04 m in the width direction, a length of 40 m in the conveyance direction, and a thickness of 0.05 mm, Droplets were discharged. The discharge conditions by the ink jet head are as follows.
(Protruding liquid)
Dipentaerystol hexaacrylate (including dimer and trimer components) 100 parts by weight Dimethoxybenzophenone (photoinitiator) 4 parts by weight Propylene glycol monomethyl ether 30 parts by weight Methyl ethyl ketone 100 parts by weight (Discharge of droplets) conditions)
Ink jet head nozzle discharge interval: 0.05 mm
Number of nozzle discharge ports of inkjet head: 500 pieces Average discharge amount of one drop: 50 pL (picoliter)

20 seconds after discharge, the film is dried at a temperature of 100 ° C., irradiated with ultraviolet rays having an irradiation intensity of 150 mJ / cm ² by a curing processing apparatus, and has a dome-shaped convex portion as shown in FIG. 7 and FIG. Was made.
The diameter of the convex portion was measured with a dimension measuring microscope (measuring microscope and two-dimensional data processing device, manufactured by Mitutoyo Corporation), and was 60 μm. Moreover, when the height h of the entire gap holding tape E2 including the convex portion was measured by a thickness measuring machine (thickness gauge, manufactured by Mitutoyo Corporation), it was 0.09 mm. The gap-holding tape E2 was cut out at 10 square centimeters, visually observed with a loupe, the number of convex portions was counted, and the number per square centimeter was determined as the density of the convex portions, and was 50 / cm ² .

[Preparation of gap holding tape E3]
The PEN film having a thickness of 0.10 mm, which is the base material of the gap holding tape E1, was used as the gap holding tape E3 as it was. The gap holding tape E3 is a flat tape.

[Preparation of gap holding tapes E4 to E6]
In producing the gap holding tape E1, the gap holding tapes E4 to E6 are the same as the gap holding tape E1, except that the embossing conditions are changed and the height h of the whole gap holding tape is changed as shown in Table 1. Was made.

[Production of condensing plate P1]
Alpet 20-100 (manufactured by PANAC, thickness: 123 μm, length in the width direction: 0.40 m) obtained by bonding an aluminum foil and a polyester film was used as the condenser plate P1.

[Production of condensing plate P2]
Alpet 20-100 (manufactured by PANAC, thickness 123 μm, length in the width direction 0.33 mm) in which an aluminum foil and a polyester film are bonded together was used as the condenser plate P2.

[Production of condensing plate P3]
Addition of 10 parts by mass of polytetrafluoroethylene (PTFE) and 10 parts by mass of carbon black to 80 parts by mass of granular activated carbon GS for gas phase (manufactured by Kuraray Co., Ltd.), knead and roll forming on a 300 μm thick SUS substrate Then, the condenser plate P3 was produced. As for the condensing plate P3, a roll-formed surface is used as a condensing surface.

[Prototype of drying device K1]
A drying apparatus having the same configuration as that of the drying apparatus 1A shown in FIGS. 1 and 2 was prototyped, and the produced condensing plate P1 was set. Further, the produced gap holding roller was disposed at the position of the gap holding roller 15a shown in FIGS. 1 and 2, and a drying apparatus K1 for supporting and transporting the condensing plate P1 from the lower portion by the gap holding roller was manufactured as a prototype.

[Prototype of drying device K2]
A drying apparatus K2 having a configuration similar to that of the drying apparatus 1B shown in FIGS.

[Prototype of drying device K3]
With the same configuration as the drying apparatus 1A shown in FIGS. 1 and 2, the drying apparatus was prototyped without providing the gap holding roller 15a, and the produced condensing plate P1 was set to obtain a drying apparatus K3.

[Production of Organic EL Element 1]
On a substrate of a polyethylene terephthalate film (manufactured by Teijin DuPont, 0.33 m in the width direction, 40.0 m in the transport direction, and 100 μm in thickness), a 100 nm thick ITO (Indium) using a sputtering apparatus A tin oxide film was formed as an anode.

  Further, a solution obtained by diluting Baytron P Al 4083 (poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate), Bayer Co.) to 70% with pure water under the same coating conditions as those of the light emitting layer to be described later is used. The hole injection layer was formed by coating with a length of 0.17 m in the width direction by a coating method. After coating, the substrate was dried at a surface temperature of 80 ° C. for 1 hour. It was 30 nm when it apply | coated on the conditions prepared on the board | substrate prepared separately and the film thickness of the formed positive hole injection layer was measured.

This substrate was transferred to a glove box under a nitrogen atmosphere in accordance with JIS B 9920, the measured cleanliness was class 100, the dew point temperature was −80 ° C. or lower, and the oxygen concentration was 0.8 ppm. Next, the following hole transport layer coating solution was prepared, and coated on the substrate with a length of 0.17 m in the width direction in the glove box by the slot coating method under the same coating conditions as the light emitting layer described later, A hole transport layer was formed. After coating, the substrate was dried by heating at a surface temperature of 80 ° C. for 30 minutes. It was 20 nm when it apply | coated on the board | substrate prepared separately on the same conditions and the film thickness of the formed positive hole transport layer was measured.
(Hole transport layer coating solution)
Monochlorobenzene 100.0g
ADS254BE (Poly- (N, N′-bis (4-butylphenyl) -N, N′-bis (phenyl) benzidine, manufactured by American Die Source)) 0.5 g

Subsequently, the following light emitting layer coating liquid was prepared under nitrogen atmosphere. The coating solution had a solid content concentration of 0.01% by mass and a viscosity of 0.6 mPa · s. The viscosity was measured in an environment at a temperature of 25 ° C. using a viscometer DV-II + Pro (manufactured by Brookfield) in accordance with JIS Z 8803.
(Light emitting layer coating solution)
Butyl acetate 10.00000g
H-A 0.1000g
D-A 0.0110 g
D-B 0.0002g
D-C 0.0002g

The organic materials HA, DA, DB, and DC represent the following compounds.

The prepared light emitting layer coating solution was applied onto a substrate by a slot coating method using a slit type die coater. The length of the slit type die coater in the width direction was 0.17 m, and the slit interval was 100 μm. The application conditions are as follows.
(Application conditions)
Application speed: 10 m / min
Environmental temperature during application: 25 ° C
Applied length in width direction: 0.1m
Applied length in transport direction: 40.0m
Wet film thickness: 4μm
The coating speed was measured with a laser Doppler velocimeter LV203.
Moreover, the wet film thickness was computed by the following formula.
Wet film thickness = supply amount of coating solution / (length in the width direction applied x coating speed)

After the application, it was dried under the following drying conditions by a prototype drying apparatus K1. In the drying apparatus K1, the arrangement positions of the condensing plate P1, the substrate transport roller, and the gap holding roller were adjusted, and the distance d between the condensing surface and the coating film surface was adjusted to 2.00 mm.
(Drying conditions)
Condensing surface temperature Tc: 20 ° C.
Temperature Th of coating film surface: 25 ° C
Distance d between condensation surface and coating film surface: 2.00 mm

  At the time of drying, an air nozzle DY-300 (manufactured by Kikuchi Co., Ltd., 0.33 m in the width direction, slit interval 100 μm) is installed adjacent to the drying device K1, and blown in the substrate transport direction and the width direction, Dried in an environment with outside wind. The wind speed at this time was measured using a wind speed converter 6332D (manufactured by Kanomax Co., Ltd.) and adjusted to 1.0 m / s.

Next, the following electron transport layer coating solution was prepared under a nitrogen atmosphere.
(Coating liquid for electron transport layer)
2,2,3,3-tetrafluoro-1-propanol 100.00 g
ET-A 0.75g
ET-A represents the following compound.

  The prepared coating solution for the electron transport layer was coated under the same coating conditions as those for the light emitting layer, and was dried by heating at a substrate surface temperature of 80 ° C. for 30 minutes to form an electron transport layer. The film thickness was 40 nm when it apply | coated on the conditions prepared on the board | substrate prepared separately and the film thickness of the formed electron carrying layer was measured.

When the electron transport layer was formed, the substrate was moved to the vapor deposition machine without being exposed to the atmosphere, and the pressure was reduced to 4 × 10 ⁻⁴ Pa. Note that potassium fluoride and aluminum were each placed in a tantalum resistance heating boat and attached to a vapor deposition machine.
First, a resistance heating boat containing potassium fluoride was energized and heated to form a 3 nm electron injection layer made of potassium fluoride on the substrate. Next, a resistance heating boat containing aluminum was energized and heated to form a cathode having a thickness of 100 nm made of aluminum at a deposition rate of 1 to 2 nm / s.

  A glove box having a cleanliness of class 100, a dew point temperature of -80 ° C. or less, and an oxygen concentration of 0.8 ppm measured in accordance with JIS B9920 in a nitrogen atmosphere without exposing the substrate on which the cathode is formed to the atmosphere. Moved to. In the glove box, it sealed with the glass sealing can which attached the barium oxide which is a water catching agent, and the organic EL element 1 was obtained. Barium oxide, a water-absorbing agent, is a high-purity barium oxide powder manufactured by Aldrich, which is attached to a glass sealing can with a fluorine-based semipermeable membrane (Microtex S-NTF8031Q, manufactured by Nitto Denko) with an adhesive. The attached one was prepared and used in advance. For adhesion between the sealing can and the organic EL element 1, an ultraviolet curable adhesive was used, and both were adhered by irradiating ultraviolet rays to produce a sealing element.

[Production of Organic EL Element 2]
In the production of the organic EL element 1, the organic EL element 2 was produced in the same manner as the organic EL element 1 except that the coating film of the light emitting layer was dried using the drying apparatus K2 instead of the drying apparatus K1.
In the drying device K2, the condenser plate P2 and the gap holding tape E1 were set. The thickness of each layer formed on the substrate is very small compared to the distance d between the condensing surface of the condensing plate P2 to be held and the coating film surface. Therefore, it is assumed that the distance between the condensing surface and the substrate is substantially equal to the distance d between the condensing surface and the coating film surface, so that the distance d between the condensing surface of the condensing plate P2 and the substrate is 2.00 mm. P2, the arrangement position of the conveyance roller of the substrate was adjusted.

[Production of organic EL elements 3 to 8]
In the production of the organic EL element 2, the condensing plate and the gap holding tape set in the drying device K2 are exchanged as shown in Table 1, and the distance between the condensing surface of the condensing plate and the substrate becomes the distance d shown in Table 1. Organic EL elements 3 to 8 were produced in the same manner as the organic EL element 2 except that the arrangement position of the condenser plate and the transport roller of the substrate was adjusted.

[Preparation of organic EL elements 9 to 11]
In the production of the organic EL element 1, an organic EL element 9 was produced in the same manner as the organic EL element 1 except that the light emitting layer was dried using a drying device K3 instead of the drying device K1.
In the production of the organic EL element 9, the organic EL element 9 is organic except that the arrangement position of the condensing plate P1 and the substrate transport roller is adjusted so that the distance between the condensing surface of the condensing plate P1 and the substrate is the distance d shown in Table 1. Organic EL elements 10 and 11 were respectively produced in the same manner as the EL element 9.

<Evaluation>
[Drying speed]
The film thickness was measured by LT-9000 (manufactured by Keyence Corporation) before and after drying the coating film of the light emitting layer. The drying rate (g / mm ² · s) was determined from the measured difference in film thickness.

[Dryness uniformity]
Since the luminance of the organic EL element has a correlation with the film thickness of the light emitting layer, and the film thickness of the light emitting layer has a correlation with the uniformity of drying, the luminance of each of the organic EL elements 1 to 11 is measured. The variation was evaluated as the uniformity of the light emitting layer thickness, that is, the uniformity of drying. First, using a luminance meter CS2000 (manufactured by Konica Minolta Sensing Co., Ltd.), the luminance of each of the organic EL elements 1 to 11 was measured at 300 points at intervals of 0.01 m in the width direction while changing the position in the transport direction. Among the 300 measured values, the maximum luminance value, the minimum luminance value, and the average luminance value were obtained, and the luminance variation was obtained by the following equation.
Variation in luminance = {(maximum luminance value−minimum luminance value) / average luminance} × 100

From the obtained variation in luminance, the uniformity of drying was evaluated as follows.
(Double-circle): The dispersion | variation in a brightness | luminance is less than 0.5, and it has performed very uniform drying.
A: The variation in luminance is 0.5 or more and less than 1.0, and uniform drying is achieved.
(Triangle | delta): The dispersion | variation in brightness | luminance is 1.0 or more and less than 5.0, and although the dispersion | variation is seen in a film thickness, it has dried uniformly as much as it is practical.
X: The variation in luminance is 5.0 or more, and it cannot be uniformly dried.

[Luminescence life]
A current was applied to each of the organic EL elements 1 to 8 so that the front luminance was 1000 cd / m ^2, and the organic EL elements 1 to 8 were continuously driven. The time required for the front luminance to reach 500 cd / m ^{2 which} was half the initial luminance was measured as the half-life. The measured value of the half-life of the organic EL element 8 was set to 100, and the light emission lifetimes of the organic EL elements 1 to 8 were obtained by the following formula.
Luminescence life of each organic EL element = (half life of each organic EL element) / (half life of organic EL element 8)

The obtained light emission lifetime was ranked as follows.
○: 0.9 <light emission life Δ: 0.5 <light emission life ≦ 0.9
×: Luminescence life ≦ 0.5
The rank of △ and ○ is set as the pass rank.

Table 1 below shows the evaluation results.
In addition, since the organic EL elements 9-11 had low evaluation of uniformity, evaluation of the light emission lifetime was not performed.

  As shown in Table 1, according to the organic EL elements 1 to 8 according to the examples, high drying uniformity is obtained regardless of the distance d between the condensation surface and the coating film surface. Moreover, since the light emission lifetime is also good, it can be seen that high film thickness uniformity is obtained after drying. On the other hand, in the case of the organic EL element 9 according to the comparative example, the distance d could not be maintained, and the condenser plate P1 was in contact with the coating film. In the case of the organic EL elements 10 and 11, no contact was observed, but it was estimated that the uniformity of drying was not obtained to the extent practical due to the influence of the external wind.

1A, 1B Drying device 11 Condensing plate 11a Condensing surface 12 Heating device 131, 132, 22, 23 Roller 141, 143, 21 Unwinder 142, 144, 24 Winder 15a Gap holding roller 15b Gap holding tape 151 Convex part 3 Coating device f1 Substrate f2 coating film f2a coating film surface

Claims (6)

In a drying apparatus comprising a condensing plate facing the coating film on the substrate, condensing the solvent vapor from the coating film with the condensing plate, and drying,
An apparatus for drying a coating film, comprising gap holding means for holding a distance between a condensing surface of the condensing plate and a coating film surface on the substrate at a constant value.   2. The coating film drying apparatus according to claim 1, wherein the gap holding means is a gap holding roller that is disposed between the substrate and the condenser plate to support and convey the condenser plate.   2. The coating film drying apparatus according to claim 1, wherein the gap holding means is a gap holding tape disposed between the substrate and the condenser plate.   The coating film drying apparatus according to claim 3, wherein a height of the gap holding tape is in a range of 0.1 to 4.0 mm.   The said condensation plate is a drying apparatus of the coating film as described in any one of Claims 1-4 containing the absorber of a solvent. In the drying method of the coating film, the condenser plate facing the coating film on the substrate is arranged, the vapor of the solvent from the coating film is condensed by the condensation plate, and dried.
A coating film drying method, wherein a gap holding means is disposed between the condenser plate and the substrate, and the distance between the condensation surface of the condenser plate and the coating film surface on the substrate is maintained at a constant value by the gap holding means.

Images