JP2008209583A - Manufacturing method of coated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a coated film which does not produce such a problem as to make a coated film thickness uneven when foreign matter is attached to the back surface of a film base material, or when the foreign matter is attached to the surface of a coating stage. <P>SOLUTION: The manufacturing method of a coated film is characterized in that, with respect to a coating method of evenly applying coating liquid in which microcapsules are dispersed on the surface to be coated of the film base material, the surface of the coating stage brought into contact with the back surface of the film base material is provided with a shape continuously having innumerable hollows, wherein diameters or breadths of the hollows and spaces of the adjacent hollows are 400% or less of the average particle size of the microcapsules. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a coated film, which is a display member such as a microcapsule type electrophoretic display device, and relates to a laminate comprising a film as a main material.

  In recent years, a microcapsule type electrophoresis system has been put to practical use as one of display devices utilizing the electrophoresis phenomenon. In this type of display device, positive and negatively charged black particles and white particles are placed in microcapsules filled with a transparent solvent, and an image is formed by pulling up each particle to the display surface by applying an external voltage. It is.

  The particle size of the microcapsules is several tens of μm to several hundreds of μm, and the coating liquid (11) in which the microcapsules are dispersed in a transparent binder can be applied like ink (FIG. 1). The display layer (3) is formed by coating the coating liquid (11) on the surface of the transparent conductive layer (2) formed on the transparent film substrate (1), and the resulting laminate is used as the back electrode. When (6) is attached to a base material on which an active matrix driving electrode circuit is formed, an active matrix electrophoretic display device as shown in, for example, Patent Document 1 can be obtained (FIG. 9).

  Moreover, when it adheres to the electrode substrate or electrode film in which electric circuits, such as a segment electrode and a simple matrix electrode, are formed as a back electrode (6), a passive matrix electrophoretic display device can be obtained.

Prior art documents are as follows.
JP 2000-221546 A

  However, a transparent electrode layer (2) (hereinafter referred to as transparent electrode layer (2) / transparent film substrate (1) laminate formed by applying the microcapsule coating liquid (11) on the transparent film substrate (1). Is coated on the film substrate (12)) when foreign matter (15) such as dust adheres to the back surface (12b) of the film substrate (12), or the coating stage ( When foreign matter is attached to the surface of 14), there arises a problem that the film thickness of the coating becomes non-uniform (FIG. 2).

  This is because, when foreign matter (15) such as dust exists between the back surface (12b) of the film base (12) and the coating stage (14), the foreign matter (15) pushes up the film base (12), This is because the distance from the discharge port (13) of the coating liquid (11) is narrowed, and the coating thickness is finally reduced around the position of the foreign matter. In the case of the microcapsule coating liquid (11), due to the decrease in the coating thickness, finally the dot-like coating unevenness (16) in which the density of the microcapsules is reduced (FIGS. 3 and 4).

  Since the coating liquid (11) in which the microcapsules are dispersed has high thixotropy, the uneven coating unevenness once generated during coating is not flattened or made uniform thereafter. Therefore, the coating film formed by drying the coating liquid (11) and evaporating the solvent is also formed in a non-uniform uneven shape.

To solve the above problem,
The present invention provides a coating method (11) in which a microcapsule-dispersed coating liquid (11) is uniformly applied to a coating surface (12a) of a film substrate (12), and the back surface (12b) of the film substrate (12). The surface of the coating stage (14) in contact with the surface has an infinite number of indentations, and the diameter or width of the indentations and the interval between adjacent indentations are 400% or less of the average particle diameter of the microcapsules. To do.

  According to the present invention, foreign matter adhering to the back surface (12b) of the film substrate (12) during coating enters the recess of the coating stage (14), and the foreign matter pushes up the film substrate (12). This is because it decreases (FIG. 8).

  The larger the indentation diameter or width of the coating stage (14), the greater the effect of taking in large foreign matter, but conversely, the film substrate (12) falls into the indentation, affecting the coating thickness and reducing the thickness. Create uniformity. Moreover, when the space | interval of an adjacent hollow is wide, the probability that a film base material (12) and a foreign material (15) will contact will become high. Therefore, it is preferable that the diameter or width of the recesses and the interval between adjacent recesses be 400% or less of the average particle size of the microcapsules.

  Further, the depression of the coating stage (14) can be, for example, a dot shape or a circular shape (FIG. 5), but can also be a stripe shape (FIG. 6) or a lattice shape (FIG. 7).

  Further, the depth of the indentation can be arbitrarily selected from the size of the most influential foreign matter.

  As a method for applying the microcapsule coating liquid (11), the microcapsule and binder resin, and the solvent coating liquid (11) are wire bar coat, slot die coat, lip die coat, comma coat, blade coat, gravure coat, etc. It is obtained by coating with, and then drying.

  As the coating stage (14), there are a planar stage and a roll stage. For example, a film base (12) is set on a flat stage and coated with slot die coating (FIG. 1), or a roll-shaped film base is wound on a roll stage and coated with a comma coat. There are methods to work.

  1 is a basic configuration of a display device of the present invention.

  The laminate of the front transparent film substrate (1) / front transparent conductive layer (2) / display layer (3) / back metal conductive layer (4) / back film substrate (5) will be described.

  The transparent substrate (1) is located on the surface of the laminate of the display device. Therefore, high transparency is required, and it is necessary to be able to be a carrier for the transparent electrode (2) and the microcapsule type electrophoretic display layer (3). Examples of such a substrate include transparent polymer films such as polyethylene terephthalate, polymethyl methacrylate, polycarbonate, polyethylene naphthalate, polypropylene, nylon-6, nylon-66, polyvinylidene chloride, and polyethersulfone, and glass plates. Can be used.

The transparent electrode (2) is not particularly limited as long as it is highly conductive and can form an electrode. However, from the viewpoint of transparency and practical use, ITO (Indium Tin Oxide), ZnO, SnO _2, etc. It is preferable to form the metal oxide transparent material by a dry film forming method. Examples of the dry film forming method include a vacuum vapor deposition method, a sputter vapor deposition method, an ion plating method, a laser vapor deposition method, and an ion beam vapor deposition method.

  As the back electrode (4), an electrode substrate or an electrode film on which an electric circuit such as an active matrix electrode, a segment electrode, or a simple matrix electrode is formed can be used.

  The microcapsule type electrophoretic display layer (3) can be obtained by applying a coating liquid (11) composed of microcapsules, a binder, a solvent and the like. In the microcapsules, charged particles of black electrophoretic particles and white electrophoretic particles are dispersed in an insulating electrophoretic dispersion medium, and are charged either positively or negatively.

  In the transparent base material (1) / transparent electrode (2) / microcapsule type electrophoretic display layer (3) / back electrode (4), which is the basic configuration described above, between the transparent electrode (1) and the back electrode (4). When the transparent electrode side is a negative electrode and the back plate side is a positive electrode, negatively charged particles are drawn to the back electrode side, and positively charged particles are drawn to the transparent electrode side. Display is possible.

  The constituent material of the microcapsule type electrophoretic display layer (3) will be described.

  As the black electrophoretic particles, black pigments such as aniline black and carbon black are used. The white electrophoretic particles use inorganic pigments such as titanium oxide, aluminum oxide, zinc oxide, and zinc sulfide, fine powders such as glass or resin, and composites thereof.

  The electrophoretic dispersion medium is formed of an insulating liquid that has good charged particles and can be stably charged, that is, an organic solvent that is substantially insoluble in water. For example, long-chain alcohol solvents such as dodecanol and undecanol, polycarbon ketones such as dibutyl ketone and methyl isobutyl ketone, aliphatic hydrocarbons such as pentane, hexane and octane, and alicyclic groups such as cyclohexane and methylcyclohexane Benzenes with long-chain alkyl groups such as hydrocarbons, benzene, toluene, xylene, hexylbenzene, butylbenzene, octylbenzene, nonylbenzene, decylbenzene, undecylbenzene, dodecylbenzene, tridecylbenzene, tetradecylbenzene, etc. Aromatic hydrocarbons, halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride and 1,2-dichloroethane, and various oils such as silicone oil and olive oil, or a mixture thereof. Be mentionedThis dispersion medium can also be colored by dissolving or dispersing a colorant such as a dye.

  The material for forming the microcapsules is preferably a material that transmits light sufficiently. Specifically, urea-formaldehyde resin, melamine-formaldehyde resin, polyester resin, polyurethane resin, polyethylene resin, polystyrene resin, polyamide resin, acrylic resin are preferable. Examples include acid ester resins, methacrylic ester resins, vinyl acetate resins, and gelatin. These may be used alone or in combination of two or more.

  Specific examples of the present invention are shown below.

  In the examples, the following film base material, microcapsule coating liquid (11), and processing conditions were all applied.

  An ITO layer is formed by sputtering as a transparent electrode layer (2) on a transparent film substrate (1) made of polyethylene terephthalate (PET), and consists of a laminate of transparent film substrate (1) / transparent electrode (2). A film substrate (12) was obtained. The transparent film substrate is 100 μm thick and 350 mm square.

  The microcapsule coating liquid (11) was prepared by stirring the components of microcapsules having an average particle size of 80 μm, a binder and a solvent at a weight ratio of 70/5/25 wt%.

  As a coating method, slot die coating was used, and the microcapsule coating liquid (11) after coating was dried at 90 ° C. for 5 minutes.

  For the evaluation of the uniformity of the coating thickness, 50 coatings were carried out under the above conditions, and then the density of the coating was visually determined through transmitted light. The number of points with a thin coating thickness was counted.

  A film substrate is placed on a coating stage that is flat and is continuously dotted with circular recesses having diameters and intervals of 50, 150, and 300 μm, and a microcapsule coating solution (11) is prepared. Coated. Thereafter, the coated surface of the microcapsule was observed through transmitted light.

  A film substrate is placed on a coating stage that is flat and has continuous indentations with stripes having a diameter and interval of 50, 150, and 300 μm, and a microcapsule coating solution (11) is prepared. Coated. Thereafter, the coated surface of the microcapsule was observed through transmitted light.

(Comparative Example 1)
A film substrate was placed on a flat and mirror-coated stage, and a microcapsule coating solution (11) was applied. Thereafter, the coated surface of the microcapsule was observed through transmitted light.

(Comparative Example 2)
A film substrate was placed on a coating stage that was flat and was continuously dotted with circular recesses having a diameter and interval of 800 μm, and the microcapsule coating liquid (11) was applied. Thereafter, the coated surface of the microcapsule was observed through transmitted light.

(Comparative Example 3)
A film substrate was placed on a coating stage which was flat and striped in the form of stripes having a diameter and interval of 800 μm, and the microcapsule coating liquid (11) was applied. Thereafter, the coated surface of the microcapsule was observed through transmitted light.

  The results of Examples 1-2 and Comparative Examples 1-3 are shown in Table 1. In all cases, spot-like coating unevenness (16) due to foreign matter occurred, but the number of occurrences in Examples 1 and 2 decreased to about 30% compared to Comparative Example 1 which is a conventional coating method. On the other hand, in Comparative Examples 2 and 3, the dot-like coating unevenness (16) was reduced, but the coating unevenness (16) on which the hollow shape of the coating stage was projected occurred on the entire surface.

It is a schematic diagram which shows one example of the coating method of a microcapsule coating liquid. It is a schematic diagram which shows an example of the coating state when a foreign material exists. It is a schematic diagram which shows an example of the coating state when a foreign material exists. It is a schematic diagram which shows an example of the coating state when a foreign material exists. It is a schematic diagram which shows an example of a coating stage. It is a schematic diagram which shows an example of a coating stage. It is a schematic diagram which shows an example of a coating stage. It is a schematic diagram which shows Example 1 of this invention. It is a schematic diagram which shows a microcapsule-type electrophoretic display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front transparent film base material 2 Front transparent conductive layer 3 Display layer 4 Back surface metal conductive layer 5 Back surface film base material 6 Back electrode 8 Front plate 11 Microcapsule coating liquid 12 Film base material 12a Coating surface 12b Back surface 14 Coating stage 15 Foreign object 16 Coating unevenness 20 Recess 21 Coating jig 22 Discharge port

Claims (1)

  In the coating method in which the coating liquid in which the microcapsules are dispersed is uniformly applied to the coating surface of the film substrate, the surface of the coating stage in contact with the back surface of the film substrate has a shape with infinitely continuous depressions. A method for producing a coated film, wherein the diameter or width of the recesses and the interval between adjacent recesses are 400% or less of the average particle size of the microcapsules.

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