JP2015060027A - Coating liquid solidification method and coating liquid solidification device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method that comprises coating a coating liquid to an opening portion of a patterning substrate including a barrier wall and the opening portion, flattening the coating liquid, and then solidifying the coating liquid, and is capable of exerting a strict shape control and selectively controlling a position from which an electric field is generated, as compared with a method that comprises applying an electric field to an entire coated substrate.SOLUTION: A coating liquid flattening and solidifying method comprises: flattening and solidifying a coating liquid while electrically pulling up a central portion of a liquid layer surface on an interface between an air layer and a liquid layer of the coated coating liquid by coating the coating liquid to an opening portion 7 of a patterning substrate having a pattern of a barrier wall 6 and the opening portion 7 on a substrate 5; disposing the substrate 5 between two opposed electrodes; and applying an electric field between the electrodes. The coating liquid flattening and solidifying method includes: providing a plurality of electrodes smaller than the opening portion 7 to act as one of the two electrodes, the electrodes being aligned to be planar so as to correspond to a position of the opening portion 7; selecting and controlling the electrodes to which the electric field is applied and a field intensity; and thereby solidifying the coating liquid while controlling a local shape of the coating liquid coated to the opening portion 7.

Description

  The present invention is a coating liquid (ink) applied to a light-blocking partition called a black matrix of a patterning substrate used in an organic electroluminescence (EL) display, an inorganic EL display, a liquid crystal display (LCD), or the like, or an opening through which light passes. This is a manufacturing method for flattening the coating liquid (ink) after coating the coating liquid, allowing the liquid to solidify flatly when the coating liquid evaporates and drys in the partition walls and in the openings, resulting in a high-quality printed matter. The present invention relates to a method for flattening a coating liquid and an apparatus for flattening a coating liquid in an opening of a patterning substrate that can be obtained.

  In an organic electroluminescence (EL) display, an inorganic EL display, a color filter for a liquid crystal display (LCD), and the like, a light-shielding partition arranged in a pattern at regular intervals on a transparent substrate that transmits light, and a partition A substrate having an enclosed opening is used. By disposing a functional coating liquid (pigment ink) or the like in the opening through which light is transmitted, a desired image can be displayed. For example, in the case of a pattern substrate in an LCD color filter, a thin film layer made of a coating solution such as red (R), green (G), and blue (B) is regularly arranged and formed in each opening. By passing the color filter from the LCD panel, the pixels through which the illumination light has passed can be viewed, and an arbitrary color image that can be controlled by RGB can be generated.

  As a method of forming a desired thin film in the opening, a printing method or vapor deposition method in which a low-viscosity liquid is directly applied to the opening and dried, and after applying to the front surface, exposure is performed to cure only necessary portions, and then unnecessary. There is a photolithography method that removes an unnecessary portion.

  Since the vapor deposition method requires a vacuum facility, a large-scale investment is required, and the production area is limited by the scale of the vacuum apparatus, which tends to cause an increase in product cost and a decrease in productivity.

  In the photolithography method, unnecessary portions are removed after coating on the entire surface, so that the material removed without being used for the substrate is wasted. In addition, since a process of curing and removal is required after coating, the number of man-hours during production increases and the cost tends to increase.

  On the other hand, in the case of a printing method in which liquid is directly applied to the opening, the material is not wasted because it is selectively applied to the necessary part, and further, the capital investment is small because it is only a process of applying and drying the liquid. It is superior in terms of cost and productivity compared to vapor deposition and photolithography.

  In the printing method, a relief plate in which a pattern of convex portions and concave portions is formed is used. First, the coating liquid is supplied to the upper surface of the relief plate, and then the relief plate is brought into contact with the opening portion of the patterning substrate to move the liquid to the opening portion, thereby completing the printed matter.

  In the printing method as described above, it is not possible to strictly control the process of moving the coating liquid on the upper surface of the convex portion to the opening of the patterning substrate. Therefore, for example, when the wettability of the partition wall with liquid is very high, the liquid may not flow into the opening and the coating liquid may concentrate near the partition wall. In that case, the deposit formed by drying and solidifying also concentrates in the vicinity of the partition wall, and it is impossible to form a thin film having a thickness sufficient to express the functionality in the opening.

Also, depending on the conditions at which the liquid in the opening dries, the Marangoni convection of the liquid caused by the concentration distribution that occurs during drying, the non-uniformity of the drying rate due to the difference in the solvent atmosphere near the center of the substrate and the vicinity of the substrate edge Depending on the factor, the film thickness distribution of the deposit after drying and solidification changes. In recent patterning substrates, the thickness of the deposits for function development has become as fine as several μm and in some cases several tens of nanometers, and slight changes in the film thickness distribution have a significant effect on functionality. give.

  In addition to simply depositing deposits evenly in the openings, the viewing angle of color filters for liquid crystal displays (LCD) is improved by, for example, finely controlling the shape and setting the angle. There is a demand for a technology that can control the fine shape according to the application.

  As a method for controlling the shape, a method is disclosed in which the thickness of the colored layer is made uniform by applying ultrasonic vibration to the liquid when the color filter substrate is manufactured. However, in the case of this method, it is difficult to selectively apply ultrasonic vibration because the corresponding opening is a small region, and as a result, not only the liquid is poured into the opening, but also contamination outside the substrate is caused. (Patent Document 1).

  As shown above, in a patterning substrate having an opening surrounded by a partition (black matrix), when a coating liquid is applied to the opening by a printing method, it is difficult to control the liquid shape, Depending on the coating solution, there is a problem that the coating solution stays in the partition wall, and the coating solution does not flow into the opening, so that a thin film cannot be formed in the opening.

  The upper part of FIG. 1 shows an example of the formation of a thin film of the coating liquid applied to the opening 7, which is flat on the opening 7 that is surrounded by the glass substrate 5 and the partition wall 62 that is a light shielding part. When the coating liquid 8 is applied to form a thin film, the coating liquid 8 approaches the partition wall 6 side, and the center of the opening 7 becomes extremely thin.

  In order to solve the above problem, as shown in FIG. 4, the substrate coated with the coating liquid was inserted between the two metal plates facing each other and applied to the opening 7 by applying an electric field. A method of solidifying the coating liquid flatly while electrically pulling up the central portion of the liquid layer surface at the gas layer-liquid layer interface of the coating liquid has been proposed. Cannot be controlled (Patent Document 2).

JP 2009-276556 A JP 2012-194313 A

  An object of the present invention is a manufacturing method in which a coating liquid is applied to an opening of a patterning substrate having a partition (black matrix) and an opening (color pixel portion), and is solidified after being flattened. An object of the present invention is to provide a method capable of selectively controlling a position where an electric field is generated, which enables stricter shape control than a method of applying an electric field.

As means for solving the above-mentioned problems, the invention according to claim 1 is characterized in that a coating liquid is applied to an opening of a patterning substrate having a pattern of partition walls and openings on a transparent substrate surface,
By placing the substrate between two opposing electrodes and applying an electric field between the electrodes,
The coating liquid is a method for flattening and solidifying the coating liquid by controlling the cross-sectional shape while electrically pulling up the central portion of the liquid layer surface at the gas layer-liquid layer interface,
One electrode of the two electrodes is an electrode smaller than the opening,
By corresponding to the position of the opening, arranging in a plane, selecting and controlling the electrode to which the electric field is applied and the electric field strength,
A solidifying method for a coating liquid, wherein the coating liquid is solidified by controlling a local shape of the coating liquid applied to an opening.

The invention according to claim 2 is an apparatus for solidifying a coating solution applied to an opening of a patterning substrate having a partition and an opening on a transparent substrate surface.
Two electrodes facing each other, the substrate is placed between the two electrodes,
By applying an electric field between the electrodes, the coating solution applied to the opening is a coating solution flattening device that solidifies by controlling the cross-sectional shape,
One electrode of the two electrodes is constituted by a plurality of electrodes smaller than the opening,
The plurality of electrodes are provided side by side in a plane corresponding to the position of the opening,
A function to select an electrode to which an electric field is applied;
A function of controlling the local shape of the coating liquid applied to the opening by controlling the electric field strength;
And a coating solution solidifying device having a function of solidifying the coating solution.

  The invention according to claim 3 is characterized in that one of the two electrodes has a lattice shape, and the pitch of the lattice intersection and the pitch of the center of the opening are the same pitch. It is a liquid solidification device.

  According to the present invention, the coating liquid is applied in a contactless manner by using the pattern forming method and the pattern forming apparatus after applying the coating liquid to the opening surrounded by the partition walls of the patterning substrate having the partition walls by using the printing method. The desired thin film can be formed by using the organic electroluminescence (EL) display, the inorganic EL display, the color filter for liquid crystal display (LCD) and the like in the pre-drying step after coating by the printing method. A high quality pattern can be formed.

It is a conceptual sectional view showing the state of coating liquid by application of an electric field in the flattening device for coating liquid of the present invention. It is the plane conceptual diagram which showed the arrangement | positioning of the application electrode (metal) in the flat solidification apparatus of the coating liquid of this invention, and the positional relationship of a black matrix partition. In the flattening apparatus for coating liquid of the present invention, a planar concept showing the arrangement of applied electrodes (metals) and the positional relationship of black matrix partition walls when printing three colors of R, G, and B and solidifying all at once. FIG. It is a conceptual sectional view showing a state of a coating liquid by applying an electric field in a flattening apparatus composed of two metal plates which is a conventional technique.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 shows a coating solution flattening apparatus of the present invention, a state of a coating solution 8 applied to an opening 7 surrounded by a partition wall 6, and a state of the coating solution 8 when an electric field is applied. In addition, the coating liquid 8 in the opening 7 surrounded by the partition walls (black matrix) gathers in the vicinity of the partition walls 6 due to the wettability, and the film thickness increases, while the thickness at the center portion decreases. However, it is set in the flat solidifying device of the present invention, and the electric field generator 1 is connected between the upper electrode 3 at the center of the opening 7 and the metal plate 2, and the potential difference is reduced by turning on the switch. When generated, a stress corresponding to the electric field is generated in the coating liquid 8.

  At this time, the stress applied to the coating liquid 8 is caused by a discontinuous change in the direction and magnitude of the electric field due to the difference in dielectric constant between the air and the coating liquid 8, and therefore the target coating liquid 8 is electrically special. It doesn't need special properties. Further, since the liquid can be deformed in a non-contact manner, there is no danger of impurities adhering to the coating liquid in the coating liquid shape control step, and cleaning of the electric field generator 1 is not necessary.

  In addition to this stress, the liquid shape of the opening 7 is determined by the gravity applied to the liquid and the Laplace pressure acting in a direction to eliminate the uneven shape of the surface. The pattern targeted in the present invention is a minute pattern shorter than the capillary diameter, and the Laplace pressure is expressed as a product of surface tension and surface curvature. A desired shape can be created by changing the electric field applied to the opening 7 in accordance with the surface tension of the coating liquid 8.

  The lower part of FIG. 1 is a schematic diagram showing that a desired thin film distribution is formed by applying a voltage in the flat solidification device, and an electric field is generated immediately below the electrode 3 to generate a voltage immediately below the electrode 3. By pulling up the coating liquid 8, the coating liquid 8 is spread over the center of the opening 7, and a thin film can be formed on the entire opening 7.

  In addition, when the fine pattern is formed, the liquid concentrates on the periphery of the partition wall having good wettability, and the phenomenon that the liquid does not wet the entire opening 7 may occur, but by applying an electric field from the substrate side, The stress acts on the substrate side, and the liquid moves toward the substrate side, whereby the liquid can be distributed over the entire opening 7.

  Further, according to the above principle, not only the coating liquid 8 can be simply poured into the opening 7, but also the shape of the deposit can be manipulated in the opening, and a function utilizing the shape can be expressed. For example, it is possible to create a color filter with an improved viewing angle by making the coating liquid 8 at the center of the opening more intense than by flattening it and giving an inclination to the surface of the thin film so that it can be easily viewed from an oblique direction.

  FIG. 2 is a conceptual plan view showing the arrangement of the application electrodes 3 (metal) and the positional relationship of the black matrix partition walls in the coating liquid flattening apparatus as the coating liquid 8 of the present invention. The pitch of the lattice intersection and the pitch of the center of the opening are set to the same pitch, and the opening 7 is solidified after applying R ink and flattened, and then solidified after applying and flattening G ink. Then, B ink is applied and flattened, and then solidified.

  FIG. 3 shows the arrangement of the application electrode 3 (metal) and the positional relationship of the black matrix partition walls in the flattening device for coating liquid (ink) when solidifying all of the colors R, G and B after printing. The electrode 3 has a lattice shape, and the pitch of the lattice intersection and the pitch of the center of the opening are adjusted to the same pitch. In general, the dielectric properties of each of the R, G, and B inks are affected by additives and the like, and when flattening, the applied voltage may need to be slightly changed for each ink type.

  Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited to the following examples.

  On a flat and transparent glass substrate 5, a black matrix using a black pigment having a light shielding property was formed as a partition wall 6. The black matrix which is the partition wall 6 is composed of the partition wall 6 having a width of 20 μm and a height of 2 μm at intervals of 100 μm in the short direction and intervals of 500 μm in the long direction, and the size of the opening 7 is 100 μm × 500 μm.

  Next, an ultraviolet curable color ink (coating liquid) composed of R, G, and B was used as the coating liquid 8 and applied to the opening 7 surrounded by the partition walls 6 by flexographic printing.

  On the ultraviolet curable color ink (coating liquid) applied to the opening, a wired metal electrode having a long diameter of 100 μm was set at a distance of 200 μm from the coating surface. The metal electrode 3 is aligned with the position of one color of R, G, and B in the arrangement of the openings 7, is wired so as to pass through the center of the opening 7, and the electrode 3 is disposed at the center. Heat was applied to the metal electrode 3 while applying a voltage of 10 kV to evaporate and dry the color ink (coating liquid) as the coating liquid 8.

  At this time, the metal plate 2 is brought into close contact with the substrate 5.

  Furthermore, the dried coating film was irradiated with ultraviolet rays to be cured and solidified. This operation was performed for each color of R, G, and B.

  With respect to the pattern substrate 5 in which the thin film made of R, G, B was formed in the opening 7 as described above, the thin film shape formed in the opening 7 was measured using a confocal microscope. Was formed. When this pattern substrate 5 was bonded to an LCD and inspected as a liquid crystal display panel, a clear color image was obtained.

<Comparative example>
In the same manner as in Example 1, openings 7 were formed on the substrate 5 by using a black matrix as the partition walls 6, and an ultraviolet curable color ink (coating liquid) composed of R, G, and B was applied by flexographic printing.

  After applying the color ink, heat was applied without applying an electric field to evaporate and solidify the coating liquid (color ink).

  The pattern substrate formed as described above was inspected using a confocal microscope. The results are shown in Table 1. A thin film made of R, G, and B was not formed at the center of the opening of the pattern substrate, and each coating liquid 8 (ink) was strongly accumulated on the upper part of the partition wall and its periphery. Further, when it was bonded to the LCD and inspected as a liquid crystal display panel, there were many portions that did not develop color, and the application as the color filter 10 was not achieved. Further, regarding the variation in smoothness of the coated thin film, the difference between the peripheral portion and the central portion of the entire substrate was small as compared with the case where two metal plates were used.

DESCRIPTION OF SYMBOLS 1 ... Electric field generator 2 ... Metal plate 3 ... Electrode 4 ... Voltage source 5 ... Substrate 6 ... Partition 7 ... Opening 8 ... Coating liquid 9 ... Wiring 10 ... color filter

Claims (3)

Applying the coating liquid to the opening of the patterning substrate having the pattern of the partition and the opening on the transparent substrate surface,
By placing the substrate between two opposing electrodes and applying an electric field between the electrodes,
The coating liquid is a method for flattening and solidifying the coating liquid by controlling the cross-sectional shape while electrically pulling up the central portion of the liquid layer surface at the gas layer-liquid layer interface,
One electrode of the two electrodes is an electrode smaller than the opening,
By corresponding to the position of the opening, arranging in a plane, selecting and controlling the electrode to which the electric field is applied and the electric field strength,
A solidifying method for a coating liquid, comprising: controlling a local shape of the coating liquid applied to the opening to solidify the coating liquid. An apparatus for solidifying a coating solution applied to an opening of a patterning substrate having a partition and an opening on a transparent substrate surface,
Two electrodes facing each other, the substrate is placed between the two electrodes,
By applying an electric field between the electrodes, the coating solution applied to the opening is a coating solution flattening device that solidifies by controlling the cross-sectional shape,
One electrode of the two electrodes is constituted by a plurality of electrodes smaller than the opening,
The plurality of electrodes are provided side by side in a plane corresponding to the position of the opening,
A function to select an electrode to which an electric field is applied;
A function of controlling the local shape of the coating liquid applied to the opening by controlling the electric field strength;
And a coating liquid solidifying device characterized by having a function of solidifying the coating liquid.   3. The coating solution solidifying apparatus according to claim 2, wherein one of the two electrodes has a lattice shape, and the pitch of the lattice intersection and the pitch of the center of the opening are the same.

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