JP2012028180A - Method and apparatus for manufacturing display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a display device with high production efficiency, the display device including a luminous layer excellent in film thickness uniformity within a cell.SOLUTION: A method for manufacturing a display device including a support substrate, a barrier forming a plurality of pixel regions and a luminous layer includes the steps of: coating an ink composition in each of the pixel regions to form a coating layer, the ink composition containing a luminescent material, a first solvent and a second solvent and having a viscosity of 5-25 mPa s; subjecting the coating layer to primary drying under atmospheric pressure conditions to adjust the viscosity to 35-55 mPa s; and subjecting the coating layer whose viscosity is adjusted to secondary drying under reduced pressure conditions to form a luminous layer. In the method, a boiling point of the second solvent is lower than that of the first solvent by 5-50°C.

Description

  The present invention relates to a display device manufacturing method and a display device manufacturing apparatus.

  In recent years, devices using organic electroluminescent elements (organic EL elements) have been put into practical use as displays for video equipment, personal computers, portable terminals, and the like. Recently, research and development of large display devices (organic EL display panels) using organic EL elements have been conducted.

  In a general organic EL element used for an organic EL display panel, a light emitting layer is formed in a pixel region (cell) delimited by a partition arranged on a glass substrate. In recent years, attempts have been made to apply a technique for applying an ink composition containing a light emitting material for forming a light emitting layer to a predetermined position by an inkjet method in a production process of an organic EL display panel (for example, Patent Document 1).

  As important elements required for a display, there are no luminance unevenness and color unevenness, and it can be lit for a long time. These are closely related to the thickness of the light emitting layer formed in the pixel region, and the variation in the thickness of the light emitting layer in one cell causes the quality to deteriorate.

  “Variation in the thickness of the light emitting layer in one cell” (hereinafter also referred to as “intracell variation”) means that the thickness of the light emitting layer is not uniform in one cell. In particular, in the case of a self-luminous element such as an organic EL element, the current density is high in a portion where the light emitting layer is thin, and there is a high possibility that excessive current concentration occurs and a short circuit occurs. This greatly affects the life of the display. In addition, if there is variation within a cell, local luminance unevenness may occur within one cell. For this reason, the thickness of the light emitting layer in one cell is required to be uniform.

  In addition, when the viscosity of the ink composition discharged with an inkjet printing apparatus is high, it becomes difficult to discharge an ink composition stably. For this reason, the viscosity of the ink composition for forming the light emitting layer of the organic EL display panel is adjusted to a low viscosity of about 10 mPa · s. However, in order to form a light emitting layer using a low-viscosity ink composition, it is necessary to devise a technique for suppressing the occurrence of in-cell variation by adjusting the drying speed of the ink composition.

  For example, in Patent Document 2, in the case where there is a difference in the drying speed for each droplet of the ink composition dropped into a plurality of cells, a droplet for adjusting the drying rate is further dropped on a specific cell. A technique for reducing the difference in drying speed is described. According to this method, since the drying speed of droplets can be adjusted, it is said that occurrence of in-cell variation can be suppressed.

Japanese Patent No. 4374197 JP 2006-212589 A

  However, in the method described in Patent Document 2, there is a process of dropping droplets for adjusting the drying speed (printing process), and thus there is a problem that the number of processes is large and the production efficiency is low as compared with the conventional technique. is there. Further, since this method is a method of slowing the drying speed of the droplets of the ink composition having a high drying speed, there is a problem that the time required for drying the ink composition becomes long.

  The present invention has been made in view of such problems of the prior art, and the problem is that a display device including a light emitting layer having excellent film thickness uniformity in a cell has high production efficiency. It is to provide a manufacturing method.

  Furthermore, the subject of this invention is providing the manufacturing apparatus which can manufacture the display apparatus provided with the light emitting layer excellent in the film thickness uniformity in a cell with high production efficiency.

  That is, according to the present invention, the following display device manufacturing method and display device manufacturing apparatus are provided.

  [1] A support substrate, a partition wall disposed on the support substrate and forming a plurality of pixel regions partitioned in a matrix or a line, and a light emitting layer disposed in each of the pixel regions. The display device is manufactured by applying an ink composition containing a light emitting material, a first solvent, and a second solvent and having a viscosity of 5 to 25 mPa · s in each of the pixel regions. Forming a coating layer, primarily drying the formed coating layer under atmospheric pressure conditions to adjust the viscosity of the coating layer to 35 to 55 mPa · s, and adjusting the viscosity. Forming a light emitting layer by subjecting the coating layer to secondary drying under reduced pressure, wherein the boiling point of the second solvent is 5 to 50 ° C. lower than the boiling point of the first solvent. Production method.

  [2] The method for manufacturing a display device according to [1], wherein the boiling point of the first solvent is 200 to 250 ° C., and the boiling point of the second solvent is 150 to 245 ° C.

  [3] The display according to [1] or [2], wherein the volume ratio of the first solvent and the second solvent contained in the ink composition is 90/10 to 60/40. Device manufacturing method.

  [4] The first solvent is at least one selected from the group consisting of cyclohexylbenzene, butyl benzoate, and 1,4-bis (methoxymethyl) benzene, and the second solvent is amylbenzene, The production of the display device according to any one of [1] to [3], which is at least one selected from the group consisting of heptylbenzene, 2,3-dihydro-2-methylbenzofuran, hexylbenzene, and butylphenyl ether. Method.

  [5] The method for manufacturing a display device according to any one of [1] to [4], wherein the ink composition is applied by an inkjet method to form the coating layer.

  [6] A coating chamber having a coating head for coating an ink composition containing a light emitting material and an organic solvent in a plurality of pixel regions on a substrate, and discharging the vapor of the organic solvent to the outside of the coating chamber. And a first ventilation means for ventilating the room.

  [7] A transport chamber that transports the substrate coated with the ink composition out of the coating chamber, and a second chamber that exhausts the vapor of the organic solvent to the outside of the transport chamber to ventilate the transport chamber. The display device manufacturing apparatus according to [6], further comprising: a ventilation means.

  [8] The display device manufacturing apparatus according to [6] or [7], wherein the coating head is an inkjet head.

  According to the display device manufacturing method and the display device manufacturing apparatus of the present invention, a display device including a light emitting layer having excellent film thickness uniformity in a cell can be manufactured with high production efficiency.

It is a schematic diagram which shows an example of a display apparatus partially. It is a schematic diagram which shows the evaporation state of the organic solvent contained in the droplet of an ink composition. It is a schematic diagram explaining the relationship between the evaporation rate of an organic solvent, and the shape of the dry film | membrane formed. It is a schematic diagram explaining the drying process of a droplet. It is a graph which shows the relationship between the leaving time of a droplet and the film thickness of the formed dry film. It is a graph which shows the relationship between the leaving time of a droplet and a viscosity. It is a graph which shows the relationship between the mixing ratio of two types of organic solvents contained in a mixed solvent, and the boiling point of a mixed solvent. It is a graph which shows the measurement result of the film thickness of the dry film formed in the reference example. It is a schematic diagram which shows one Embodiment of the manufacturing apparatus of the display apparatus of this invention.

1. Method for Manufacturing Display Device FIG. 2 is a schematic diagram showing an evaporation state of an organic solvent contained in a droplet of an ink composition. As shown in FIG. 2, the drying speed of the ink composition droplets 102 (the evaporation speed 201 of the organic solvent) is the highest at the portion in contact with the partition wall 101. That is, since the organic solvent contained in the droplet 102 is quickly vaporized at the portion in contact with the partition wall 101, an imbalance occurs in the solute concentration between the central portion and the peripheral portion of the droplet 102. For this reason, as the drying progresses, an ink stream 202 (Rayleigh / Marangoni convection) that makes the solute concentration uniform is generated. The lower the viscosity of the droplets 102 in the initial stage of drying, the easier the ink stream 202 is generated. Further, the faster the organic solvent evaporation rate 201 is, the more easily the ink stream 202 is generated. Drying proceeds while the evaporation rate 201 of the organic solvent and the flow rate of the ink stream 202 are balanced, and the droplet 102 is formed into a film. Note that the viscosity of the ink composition forming the droplets 102 increases with the progress of drying and restricts the ink flow 202, so that the thickness of the formed film tends to be non-uniform.

  FIG. 3 is a schematic diagram for explaining the relationship between the evaporation rate of the organic solvent and the shape of the formed dry film. 3A, 3B, 3C, and 3D show a state in which the evaporation rate of the organic solvent is high. In the case where the evaporation rate of the organic solvent is low (FIG. 3A), a dry film 302 having a shape similar to the shape of the droplet, with the central portion raised, is formed. When the evaporation rate of the organic solvent is increased, the solute at the central portion of the droplet is carried to the outer peripheral portion of the droplet, so that a concave portion is formed at the central portion (FIG. 3B). When the evaporation rate of the organic solvent further increases, the central concave portion becomes extreme, and a protruding portion 304 is formed on the outer peripheral portion (FIG. 3C). When the evaporation rate of the organic solvent is further increased, a skirt portion 301 having a very thin film thickness is formed at the base of the protruding portion 304 (FIG. 3D). As shown in FIG. 2, since the shape of the dry film formed is determined by the ink flow during drying, the relationship between the evaporation rate causing the ink flow and the viscosity of the ink composition should be appropriately controlled. Thus, a dry film having a uniform film thickness can be formed.

  FIG. 4 is a schematic diagram for explaining a drying process of droplets. FIG. 4A is a schematic diagram showing a process in which droplets are dried in a normal state. Since the organic solvent uniformly evaporates from the surface of the droplet 220 disposed on the support substrate 210, the volume decreases while maintaining a similar shape. This drying mode is called a CCA (Constant Contact Angle) mode because the contact angle with the substrate is constant.

  FIG. 4B is a schematic diagram showing the process of drying the droplets with the ends of the droplets fixed. In this case, the evaporation of the organic solvent proceeds in the vicinity of the droplet end portion 230, and in order to compensate for the decrease in the evaporated organic solvent, a flow of the organic solvent is generated from the central portion of the droplet 220 toward the droplet end portion 230. To do. This drying mode is called a CCR (Constant Contact Radius) mode because the droplet diameter is constant.

  4 (C) and 4 (D) are schematic diagrams showing the state of solute distribution in the CCR mode. FIG. 4C is a schematic diagram showing a solute distribution before drying, and FIG. 4D is a schematic diagram showing a solute distribution during drying. As shown in these figures, in the CCR mode, the solute 240 moves on the flow of the organic solvent. As a result, the concentration of the solute 240 increases in the vicinity of the droplet end 230.

  FIG. 4E is a schematic diagram showing the evaporation rate of the solvent in the CCR mode. As shown in this figure, the evaporation rate 250 of the organic solvent on the surface of the droplet 220 is not uniform as in the CCA mode, and increases rapidly as the droplet end 230 is approached. As a result, the moving speed of the organic solvent also increases rapidly as it approaches the droplet end 230.

FIG. 5 is a graph showing the relationship between the time for which droplets are left and the thickness of the formed dry film. Specifically, a droplet of an ink composition (viscosity: 10 mPa · s) obtained by dissolving a solute (polyfluorene) in cyclohexylbenzene (CHB) is placed on a supporting substrate 110 (W ₁ : 60 μm, W ₂ : 180 μm, H: 1 μm), and after standing for a predetermined time at room temperature and normal pressure, the film thickness of a dried film formed by drying under reduced pressure is measured. As shown in FIG. 5, the flatter dry film is formed as the standing time is longer. This is presumably because part of the organic solvent evaporates during the standing time, the viscosity of the ink composition increases, and the ink flow in the droplets is suppressed.

  FIG. 6 is a graph showing the relationship between the droplet standing time and the viscosity. The viscosity of the droplet (ink composition) was measured using a rotary viscometer (model number “AR-G2”, manufactured by TA Instruments) using a cone having a tip angle of 1 ° and R of 40 mm. . In FIG. 6, the viscosity at a shear rate of 500 / s is plotted. As shown in FIG. 6, the viscosity of the ink composition increases exponentially as the standing time increases. Further, when the standing time is 20 minutes, the viscosity of the ink composition increases to 40 mPa · s. Also in Patent Document 2, it is confirmed that the film thickness of the dry film is made uniform over time. However, in the method described in Patent Document 2, the production efficiency is low because droplets for adjusting the drying rate are dropped to slow the drying rate. As described above, the present inventors can form a dry film (light-emitting layer) excellent in film thickness uniformity with high production efficiency if the viscosity is rapidly increased after applying a droplet of the ink composition. I found.

  FIG. 7 is a graph showing the relationship between the mixing ratio of two organic solvents contained in the mixed solvent and the boiling point of the mixed solvent. Specifically, a mixed solvent of CHB (A solvent, boiling point: 240 ° C.) generally used in the ink composition and heptylbenzene (B solvent, boiling point: 235 ° C.) is used. As shown in FIG. 7, by mixing the high boiling point A solvent and the low boiling point B solvent, the resulting mixed solvent has a lower boiling point than the boiling point of the A solvent. Here, for the low-viscosity organic solvent used in the inkjet method, a correlation is observed between the boiling point and the evaporation rate. Therefore, by mixing a second solvent having a lower boiling point with a solvent (first solvent) such as CHB generally used in the ink composition, the evaporation rate of the obtained mixed solvent is set to the first rate. It is possible to make it faster than the evaporation rate of the solvent. As described above, the present inventors can increase the drying speed and use the ink composition (droplet) viscosity by using an ink composition prepared with a mixed solvent containing two or more organic solvents having moderately different boiling points. It was found that it was possible to quickly increase to the value of.

(Manufacturing method of display device)
In the method for manufacturing a display device of the present invention, an ink composition containing a light emitting material, a first solvent, and a second solvent and having a viscosity of 5 to 25 mPa · s is applied to each pixel region. A step of forming a coating layer (hereinafter also referred to as “first step”) and a step of primarily drying the formed coating layer under atmospheric pressure conditions to adjust the viscosity of the coating layer to 35 to 55 mPa · s. (Hereinafter also referred to as “second step”), and a step of forming a light emitting layer by secondarily drying the coating layer whose viscosity has been adjusted under reduced pressure conditions (hereinafter also referred to as “third step”); ,including. Hereinafter, the detail of each process is demonstrated.

(First step)
In the first step, an ink composition containing a light emitting material, a first solvent, and a second solvent is applied in a pixel region surrounded by a partition wall. A partition wall defining the pixel region is formed on the support substrate. The kind of support substrate will not be specifically limited if it has desired transparency and mechanical characteristics. Specific examples of the support substrate include a glass plate, a plastic plate, a ceramic plate, and a metal plate (for example, an aluminum plate). The support substrate may be subjected to surface treatment such as plasma treatment or UV treatment. The shape and size of the pixel region defined by the partition walls can be freely set according to required characteristics (for example, display resolution).

  The partition walls may be arranged so that the pixel regions are arranged in a matrix, or may be arranged so that the pixel regions are arranged in a line. The plurality of pixel regions arranged in a line emit light of the same color (R, G, or B).

  The cross-sectional shape of the partition wall in the direction perpendicular to the support substrate surface is preferably rectangular or tapered. When the sectional shape of the partition wall is a taper shape, a forward taper shape is preferable. By making the shape of the partition a forward tapered shape, the film thickness uniformity of the light emitting layer described later can be further improved. When the shape of the partition wall is a forward tapered shape, the inclination angle of the side surface of the partition wall (surface facing the pixel region) is not particularly limited, and can be freely set according to required characteristics (for example, display resolution). . The material of the partition is not particularly limited, but acrylic resin, polyimide resin, novolac phenol resin, and the like are preferable in consideration of insulation, organic solvent resistance, and process resistance (resistance to plasma treatment, etching treatment, and baking treatment). . Moreover, the material of the partition may be a fluororesin (acrylic fluororesin or polyimide fluororesin). The partition wall may be subjected to a surface treatment such as plasma treatment or UV treatment, whereby the lyophilicity or liquid repellency of the partition wall surface can be adjusted.

  FIG. 1 is a schematic diagram partially showing an example of a display device. 1A is a cross-sectional view, and FIG. 1B is a plan view. The forward tapered partition 120 is formed on the support substrate 110. The light emitting layer 130 is formed in the pixel region defined by the partition 120. The light emitting layer 130 is a film formed of a light emitting material (solute) contained in the ink composition. The effective pixel region 140 is a region in the pixel region, for example, a line (indicated by a broken line in the figure) located 3.5 μm inside from the lower end of the inner surface of the partition wall 120 (the boundary line between the partition wall 120 and the support substrate 110). It is an area | region prescribed | regulated by. The effective pixel region 140 is a portion that emits light in the image display panel, for example. The shape and size of the effective pixel region 140 can be freely set according to required characteristics (for example, display resolution).

  The kind of the luminescent material contained in the ink composition can be freely selected according to the required characteristics. Specific examples of the light emitting material include low molecular weight organic light emitting materials; polymer organic light emitting materials such as polyphenylene vinylene, poniarylene, polyalkylthiophene, and polyalkylfluorene. Usually, a polymer organic light emitting material is used as a light emitting layer by a coating method, and thus is preferable as a light emitting material used in the method for manufacturing a display device of the present invention.

  The first solvent contained in the ink composition is preferably an organic solvent having a solubility parameter (sp value) in the range of 8 to 10. Such an organic solvent can dissolve 0.1% by mass or more of the above-described light emitting material (particularly, a polymer organic light emitting material). Here, the “solubility parameter” is a value proposed by Hildebrand and defined by regular solution theory, and is a value serving as a measure of the solubility of the binary solution. The solubility parameter is used as a scale representing intermolecular force, and it is empirically known that the solubility increases as the difference between the sp values of the two components decreases.

  The boiling point of the first solvent is preferably 200 to 250 ° C, more preferably 210 to 250 ° C. If the boiling point of the first solvent is too low, the drying speed of the ink composition becomes too fast, and the film thickness uniformity of the formed light emitting layer tends to decrease. On the other hand, if the boiling point of the first solvent is too high, the drying speed of the ink composition becomes too slow, and the production efficiency of the display device tends to decrease.

  Specific examples of the first solvent include alkylbenzenes such as toluene, xylene, phenylnonane, cyclohexylbenzene and tetralin; alkoxybenzenes such as methoxytoluene and methoxybenzene; aromatic alcohols such as benzyl alcohol and cyclopropylbenzyl alcohol; Aromatic esters such as butyl acid; aromatic ethers such as 1,4-bis (methoxymethyl) benzene and the like. Of these, cyclohexylbenzene (boiling point: 240 ° C.), butyl benzoate (boiling point: 250 ° C.), and 1,4-bis (methoxymethyl) benzene (boiling point: 235 ° C.) are preferable. These organic solvents can be used individually by 1 type or in combination of 2 or more types.

  The boiling point of the second solvent contained in the ink composition is 5 to 50 ° C., preferably 10 to 40 ° C. lower than the boiling point of the first solvent. By using a second solvent having a boiling point lower than that of the first solvent by the above temperature range, the viscosity of the droplets of the applied ink composition is primarily dried under normal temperature and normal pressure conditions. It can be raised to a desired range in a short time.

  If the boiling point of the second solvent is too low, the drying speed of the ink composition becomes too fast. For this reason, for example, when the ink composition is applied by an ink jet method, the nozzles of the ink jet head are likely to be clogged, and stable ejection becomes difficult. On the other hand, if the boiling point of the second solvent is too high, it becomes difficult to quickly increase the viscosity of the ink composition by primary drying.

  In addition, the boiling point of a 2nd solvent is 150-245 degreeC normally, Preferably it is 180-200 degreeC. Specific examples of the second solvent include amylbenzene (boiling point: 202 ° C.), heptylbenzene (boiling point: 235 ° C.), 2,3-dihydro-2-methylbenzofuran (boiling point: 198 ° C.), hexylbenzene (boiling point: 226 ° C.) and butyl phenyl ether (boiling point: 210 ° C.). In addition, these organic solvents can be used individually by 1 type or in combination of 2 or more types.

  The volume ratio of the first solvent and the second solvent contained in the ink composition is preferably 90/10 to 60/40, and more preferably 80/20 to 70/30. If the ratio of the first solvent contained in the ink composition is too high, it tends to be difficult to quickly increase the viscosity of the ink composition by primary drying. On the other hand, if the ratio of the first solvent contained in the ink composition is too low, the drying speed of the ink composition becomes too fast, and the film thickness uniformity of the formed light emitting layer tends to be lowered.

  The viscosity of the ink composition is 5 to 25 mPa · s, preferably 9 to 11 mPa · s. When the viscosity of the ink composition is less than 5 mPa · s, the coating efficiency and the drying efficiency may decrease because the concentration of the solute is too low. On the other hand, when the viscosity of the ink composition is more than 25 mPa · s, the viscosity is too high, and thus, for example, ejection (application) by an ink jet method becomes difficult.

The “viscosity” in the present specification means a viscosity at 20 ° C. The viscosity of the ink composition or the solvent can be measured using a rheometer (for example, model number “AR-G2” manufactured by TA Instruments). In order to measure the viscosity of an ink composition or the like using a rheometer, the apex of a cone (radius: Rcm, angle) is brought into contact with a plate on which a sample is placed, and the cone is rotated at an angular velocity Ω (rad · s ⁻¹ ). Let Assuming that the rotational torque of the cone is M (N · m), the apparent viscosity η (Pa · s) is obtained by the following equation (1). Further, the shear stress S (Pa) is obtained by the following equation (2), and the shear rate D (s ⁻¹ ) is obtained by the following equation (3). The apparent viscosity η is defined as the “viscosity” of the sample.

  The method for applying the ink composition in the pixel region is not particularly limited, but the ink jet method is preferable because the ink composition can be applied accurately and simultaneously to a number of locations. Other coating methods include a die coating method.

(Second step)
In the second step, the coating layer formed in the pixel region is primarily dried under atmospheric pressure conditions. The “primary drying” means an operation of evaporating only a part of the solvent contained in the ink composition and increasing the viscosity of the coating layer. By performing this primary drying, the second solvent having a lower boiling point is mainly evaporated to increase the viscosity of the coating layer.

  By the primary drying described above, the viscosity of the coating layer is adjusted to 35 to 55 mPa · s, preferably 40 to 45 mPa · s. If the viscosity of the coating layer is out of the above numerical range, the thickness of the light emitting layer to be formed is not uniform when the coating layer is dried under reduced pressure conditions in the subsequent step (third step). This is presumably because the ink flow in the coating layer is not controlled and the drying proceeds locally.

  The ink composition when it is assumed that only the second solvent which has a lower boiling point and easily evaporates out of the first solvent and the second solvent contained in the ink composition forming the coating layer has evaporated. This viscosity is defined as “viscosity of coating layer”.

  The primary drying may be performed under heating conditions, but it is preferable to perform the drying under room temperature conditions (for example, around 25 ° C.) because special equipment is not required. The time required for primary drying is usually 20 to 30 minutes. If the primary drying time is less than 20 minutes, the viscosity of the coating layer may not increase to a desired value. On the other hand, when the time of primary drying is more than 30 minutes, the possibility that fine impurities and the like are mixed in the coating layer increases, and the production efficiency tends to decrease.

  In the primary drying, for example, (1) the substrate after application of the ink composition is left in the apparatus (application chamber) for applying the ink composition, and (2) the substrate passes through the transfer chamber to the vacuum drying chamber. It can be carried out by (3) leaving in a drying chamber. In order to shorten the time required for the primary drying, it is preferable to perform the primary drying while discharging the vapor of the solvent generated from the coating layer to the outside.

(Third step)
In the third step, the coating layer whose viscosity is adjusted to 35 to 55 mPa · s by primary drying is secondarily dried under reduced pressure conditions. Thereby, the light emitting layer excellent in film thickness uniformity can be formed. The “secondary drying” means an operation of evaporating the solvent (residual portion not evaporated by the primary drying) contained in the ink composition and drying the coating layer.

  Although secondary drying may be performed at normal temperature, it is preferable to carry out under heating conditions because the time required for drying can be shortened. In addition, it is preferable to perform secondary drying at 20-35 degreeC. The time required for drying is usually about 1 to 5 minutes.

2. Display device manufacturing apparatus The display device manufacturing apparatus of the present invention includes an application chamber having an application head and first ventilation means for ventilating the application chamber. The coating head is a member having a function of coating the ink composition in a plurality of pixel regions on the substrate. The ink composition contains a light emitting material and an organic solvent.

  The conventional coating chamber is filled with the vapor of the organic solvent evaporated from the ink composition applied on the substrate. On the other hand, since the manufacturing apparatus of the present invention has the first ventilation means for ventilating the coating chamber, the vapor of the organic solvent can be discharged to the outside of the coating chamber for ventilation. For this reason, the vapor concentration of the organic solvent in the coating chamber can be lowered. Therefore, if the manufacturing apparatus of the present invention is used, drying of the coating layer made of the ink composition coated on the substrate can proceed in the coating chamber.

  In the manufacturing apparatus of the present invention, an ink composition (hereinafter also referred to as “specific ink composition”) used in the above-described manufacturing method of the display apparatus of the present invention is preferably used when manufacturing the display device. As described above, the specific ink composition contains the first solvent and the second solvent whose boiling point is lower than the boiling point of the first organic solvent by a predetermined temperature as the organic solvent. For this reason, when the manufacturing apparatus of this invention is used and the coating layer which consists of a specific ink composition is formed in a pixel area | region, the evaporation rate of a 2nd solvent can be accelerated in a coating chamber. Therefore, it is possible to shorten the time until the coating layer made of the specific ink composition has a desired viscosity in the coating chamber.

  Specific examples of the coating head include an ink jet head and a die coating head. Among these, an inkjet head is preferable. Specific examples of the first ventilation means include a combination of a blower (intake) fan and piping, a combination of a blower (decompression) pump and piping, and the like. In addition, it is also a preferable aspect that a member capable of adsorbing or removing the vapor of the organic solvent is attached in the middle of the pipe, and the air after removing the vapor of the organic solvent is returned to the coating chamber.

  The manufacturing apparatus of the present invention includes a transfer chamber that carries the substrate coated with the ink composition out of the application chamber and moves it, and a second ventilation unit that exhausts the vapor of the organic solvent to the outside of the transfer chamber to ventilate the transfer chamber. It is preferable to further comprise. In this way, by installing ventilation means in the transfer chamber, it is possible to ventilate the organic solvent vapor to the outside of the transfer chamber. For this reason, even during the conveyance of the substrate, the drying of the coating layer made of the ink composition coated on the substrate can proceed.

  Specific examples of the second ventilation means include the same as the first ventilation means described above. Note that only one ventilation means may be arranged, and this ventilation means may be shared between the application chamber and the transfer chamber.

  Hereinafter, embodiments of the display device of the present invention will be specifically described with reference to the drawings. FIG. 9 is a schematic view showing an embodiment of the display device manufacturing apparatus of the present invention. As shown in FIG. 9, the display device manufacturing apparatus 10 of the present embodiment includes a coating chamber 15, a transfer chamber 20, and a vacuum drying chamber 25. A stage 7 on which the substrate 5 can be placed and a coating head 9 are disposed in the coating chamber 15. The stage 7 and the coating head 9 are accommodated in a housing 11 so that the vapor of the organic solvent generated from the ink composition does not leak to the outside. The coating head 9 is disposed above the stage 7 and can apply a droplet of the ink composition to a predetermined portion of the substrate 5 placed on the stage 7. A fan 30 capable of discharging the air in the coating chamber 15 containing the vapor of the organic solvent to the outside is connected to the housing 11 of the coating chamber 15 through a pipe 35. The air exhausted from the coating chamber 15 is returned to the coating chamber 15 after the vapor of the organic solvent contained therein is removed by the removing means such as the adsorption unit 40.

  The transfer chamber 20 is a portion serving as a path for transferring the substrate 22 coated with the ink composition from the application chamber 15 to the vacuum drying chamber 25. A transfer machine 24 such as a conveyor is disposed in the transfer chamber 20, and the placed substrate 22 can be transferred. A fan 30 capable of discharging the internal air containing the vapor of the organic solvent to the outside is connected to the transfer chamber 20 through a pipe 35. The air exhausted from the transfer chamber 20 is returned to the transfer chamber 20 after the vapor of the organic solvent contained therein is removed by the removing means such as the adsorption unit 40. The coating chamber 15 and the transfer chamber 20 share the same fan 30 and suction unit 40.

The vacuum drying chamber 25 includes a vacuum pump 50, a vacuum chamber 55 connected to the vacuum pump 50, and a purge line 60 connected to the vacuum chamber 55. A stage 67 on which the substrate 65 transferred from the coating chamber through the transfer chamber 20 can be placed is disposed in the decompression chamber 55. After placing the substrate 65 on the stage 67, the decompression pump 50 is driven to decompress the interior of the decompression chamber 55. Thereby, the coating layer on the substrate 65 is dried to form a light emitting layer. After introducing nitrogen (N ₂ ) gas or the like from the purge line 60 to return the inside of the decompression chamber 55 to atmospheric pressure, the substrate 65 on which the light emitting layer is formed is carried out of the decompression chamber 55.

  Hereinafter, the present invention will be described more specifically based on experimental examples.

(Reference Example 1)
Hydrogenated styrene-butadiene block copolymer (manufactured by Aldrich, CAS No. 66070-) was mixed with a mixed solvent in which CHB (boiling point: 240 ° C.) and amylbenzene (boiling point: 205 ° C.) were mixed at a volume ratio of 80:20. 58-4) was dissolved to prepare an ink composition having a viscosity of 10 mPa · s. The ink composition prepared by the inkjet method was applied between the partition walls 101 (W ₁ : 60 μm, W ₂ : 180 μm, H: 1 μm) on the support substrate 110 as shown in FIG. The coating layer thus formed was left at room temperature (25 ° C.) under atmospheric pressure conditions for 30 minutes until the viscosity of the coating layer reached 40 mPa · s. Thereafter, a dried film was formed by drying under reduced pressure at 25 ° C. for 2 minutes under a reduced pressure condition of 3 Pa.

  In addition, the viscosity of the ink composition when it is assumed that only amylbenzene has evaporated out of CHB (first solvent) and amylbenzene (second solvent) contained in the ink composition forming the coating layer. It was set as “viscosity of coating layer”.

  Using an atomic force microscope (model number “AS-7B”, manufactured by Takano Co., Ltd.), the shape of the dry film in a cross section passing through the center in the longitudinal direction of the pixel region was measured, and the film thickness of the dry film was measured. In addition, model number "OMCL-AC160TS" (Olympus Corporation) was used for the probe. The measurement results are shown in FIG.

(Comparative Reference Example 1)
A dry film was formed in the same manner as in Reference Example 1 except that a single solvent of CHB was used instead of the mixed solvent of CHB and amylbenzene. The measurement result of the film thickness of the formed dry film is shown in FIG.

(Evaluation)
As shown in FIG. 8, it is clear that Reference Example 1 can form a dry film having excellent film thickness uniformity with a film thickness difference of ± 4 nm. This is presumably because the ink flow generated due to the difference in the partial drying rate of the ink composition at the edge of the coating layer was suppressed by the increase in the viscosity of the ink composition before drying under reduced pressure. . On the other hand, in Comparative Reference Example 1, it can be seen that a dry film having inferior film thickness uniformity as compared with Reference Example 1 was formed.

(Reference Example 2)
A dry film was formed in the same manner as in Reference Example 1 except that a mixed solvent of CHB and heptylbenzene (boiling point: 235 ° C.) was used instead of the mixed solvent of CHB and amylbenzene. When the film thickness of the formed dry film was measured, it was found that a dry film excellent in film thickness uniformity equivalent to that in Reference Example 1 was formed.

(Reference Example 3)
Instead of the mixed solvent of CHB and amylbenzene, a mixed solvent of CHB and 2,3-dihydro-2-methylbenzofuran (boiling point: 198 ° C.) was used as in Reference Example 1 described above. A dry film was formed. When the film thickness of the formed dry film was measured, it was found that a dry film excellent in film thickness uniformity equivalent to that in Reference Example 1 was formed.

(Comparative Reference Example 2)
The ink composition was prepared in the same manner as in Reference Example 1 except that a mixed solvent of CHB and 2,3-dihydrobenzofuran (boiling point: 189 ° C.) was used instead of the mixed solvent of CHB and amylbenzene. Prepared. When the prepared ink composition was applied by the ink jet method, nozzle clogging occurred during maintenance of the ink jet apparatus, and the ink composition could not be applied (discharged) stably. This is presumably because the boiling point of 2,3-dihydrobenzofuran is too low.

  The display device manufacturing method of the present invention is suitable as a method for manufacturing an organic EL display panel that requires a large area and uniform film formation.

5,22,65 Substrate 7,67 Stage 9 Coating head 10 Display device manufacturing apparatus 11 Housing 15 Coating chamber 20 Transfer chamber 24 Transfer machine 25 Depressurization drying chamber 30 Fan 35 Piping 40 Suction unit 50 Decompression pump 55 Depressurization chamber 60 Purge line 110, 210, 303 Support substrate 101, 120 Partition wall 102, 220 Droplet 105 Coating layer 130 Light emitting layer 140 Effective pixel region 202 Ink flow 230 Droplet edge 240 Solute 201, 250 Evaporation rate of organic solvent 301 Bottom portion 302 Drying film 304 Protrusion

Claims (8)

A display device comprising: a support substrate; a partition wall formed on the support substrate and forming a plurality of pixel regions partitioned in a matrix or a line; and a light emitting layer disposed in each of the pixel regions A method of manufacturing
Applying an ink composition containing a light emitting material, a first solvent, and a second solvent and having a viscosity of 5 to 25 mPa · s in each of the pixel regions, and forming a coating layer;
Primary drying the formed coating layer under atmospheric pressure conditions to adjust the viscosity of the coating layer to 35 to 55 mPa · s;
Forming the light emitting layer by secondarily drying the coating layer whose viscosity is adjusted under reduced pressure,
The method for manufacturing a display device, wherein the boiling point of the second solvent is 5 to 50 ° C. lower than the boiling point of the first solvent.   The method for manufacturing a display device according to claim 1, wherein the boiling point of the first solvent is 200 to 250 ° C., and the boiling point of the second solvent is 150 to 245 ° C. 2.   The method for manufacturing a display device according to claim 1, wherein a volume ratio of the first solvent and the second solvent contained in the ink composition is 90/10 to 60/40. The first solvent is at least one selected from the group consisting of cyclohexylbenzene, butyl benzoate, and 1,4-bis (methoxymethyl) benzene;
The second solvent is at least one selected from the group consisting of amylbenzene, heptylbenzene, 2,3-dihydro-2-methylbenzofuran, hexylbenzene, and butylphenyl ether. A method for manufacturing a display device according to one item.   The manufacturing method of the display apparatus as described in any one of Claims 1-4 which apply | coat the said ink composition by the inkjet method, and form the said application layer. A coating chamber having a coating head for coating an ink composition containing a light emitting material and an organic solvent in a plurality of pixel regions on the substrate;
A first ventilation means for venting the inside of the coating chamber by discharging the vapor of the organic solvent to the outside of the coating chamber;
A display device manufacturing apparatus comprising: A transfer chamber for moving the substrate coated with the ink composition out of the application chamber; and
A second ventilation means for ventilating the inside of the transfer chamber by discharging the vapor of the organic solvent out of the transfer chamber;
The display apparatus manufacturing apparatus according to claim 6, further comprising:   The display device manufacturing apparatus according to claim 6, wherein the coating head is an inkjet head.

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