JPH09230129A - Method for manufacturing color filter and liquid crystal display device using the same - Google Patents

Abstract

(57) Abstract: When a color filter is formed by an inkjet method, a colored layer having a uniform thickness is obtained in a pixel portion, ink spread in the pixel is improved, and color loss in the pixel occurs. So that it does not occur. SOLUTION: By using a water-based ink and irradiating with ultraviolet rays, the ink repellency of the upper surface 4 of the convex portion 2 partitioning the pixels is made 90 ° or more in terms of the contact angle of water, and the ink affinity of the concave portion is made into the contact angle of water. By setting the angle to 20 ° or less, a color filter having no color drop around the pixel is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a color filter by forming a convex portion on a substrate and coloring a concave portion surrounded by the convex portion by an ink jet method, and a liquid crystal display device using the same. .

[0002]

2. Description of the Related Art Various manufacturing methods have been proposed for color filters for liquid crystal display devices. In particular, several methods are known for producing a color filter by forming a colored layer on the inner wall side of a cell of a substrate.

For example, there is a method of forming a colored layer by pattern printing of a colored ink by an offset printing method or the like. However, there is a limit to fineness of a printed pattern, and there is a problem such as a decrease in production yield.

[0004] A pigment dispersion method is often used as a method of applying a colored ultraviolet curable ink on the entire surface of a substrate and forming a color filter pattern by a photolithographic method. However, in the pigment dispersion method, it is necessary to perform coating, ultraviolet irradiation, and development steps three times in order to produce three primary color filters of red, green, and blue, which is extremely complicated in the manufacturing process.

[0005] In addition, in a method of manufacturing a color filter using an electrodeposition coating method, a transparent electrode having a pattern is formed in advance on a portion to be electrodeposited, and three color filters are manufactured. To this end, the respective electrodes are sequentially energized to form a color filter film on the transparent electrodes. This method requires three electrodeposition operations, an operation to prevent color mixing due to overlapping colors, and a transparent electrode corresponding to the three colors. May be subject to restrictions.

As a rational method for manufacturing a color filter that solves these problems, Japanese Patent Application Laid-Open No. 59-75205 proposes to form a colored layer by spraying a colored ink by an ink jet method. When coloring with an inkjet method, the droplet diameter is several tens of μm,
On the other hand, the pixels of the color filter are generally several tens of μm on the short side,
The long side is about several hundred μm. For this reason, it is possible to obtain uniform pixels by providing the glass substrate with sections for defining pixels in advance and spraying the ink into the sections by the ink jet method to spread the ink in the sections.

The above-mentioned proposal describes a method in which, when an ink having good wettability to a glass substrate is used, a convex portion serving as a boundary is printed in advance with a substance having poor wettability to the ink. . Further, in the case of using an ink having poor wettability with respect to glass, there has been proposed a method of forming a pattern on the glass in advance with a material having good wettability with the ink and helping the ink to be fixed. Further, Japanese Patent Laid-Open No. 6-347637 proposes to use a combination in which the pixel portion is easily wetted with ink and the black mask is hard to be wetted.

[0008]

However, in many cases, sufficient hydrophilicity of the pixel portion cannot be obtained due to various contaminations when forming the black mask. Usually, the black mask is formed by etching using a resist protective film,
A method is used in which the material for forming the black mask has photosensitivity and is patterned by photolithography. However, the etching solution or the developing solution may not completely peel off the unnecessary portion, which may impair the hydrophilicity of the glass surface.

In particular, when imparting ink repellency to the black mask, since an ink repellent substance is used, even a slight contamination tends to greatly impair the affinity between the ink and the substrate.
If the pixel portion is not sufficiently ink-philic as described above, there is a problem in that the ink does not spread sufficiently in the concave portion and color loss easily occurs in the peripheral portion of the pixel. When this color filter is used in a liquid crystal display element or the like, problems such as color unevenness and deterioration of contrast due to leakage of light due to defective coloring are likely to occur.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, in which a convex portion is formed on a base material, and ink is applied to a concave portion separated by the convex portion by an inkjet method. In a method of manufacturing a color filter in which ink is sprayed to deposit ink in a concave portion to form a colored layer, after forming the convex portion, the ink affinity of the concave portion is controlled by irradiating an energy ray, and then the ink is formed by an inkjet method. Provided is a method for manufacturing a color filter characterized by spraying.

Further, the method of manufacturing a color filter in which the contact angle of water in the concave portion is 20 ° or less by the treatment of irradiating the energy rays, and the convex portions thereof are
A method for producing a color filter that is also used as a black mask, a method for producing a color filter that irradiates those energy rays from the surface of the substrate opposite to the side where the convex portion is formed, and those energy rays Provided is a method for manufacturing a color filter, which comprises irradiating from both sides of a substrate and controlling the respective irradiation amounts so that the ink repellency of the convex portions and the ink affinity of the concave portions have desired values.

Further, the surface of the convex portions is RSiX.
YZ (R represents a hydrocarbon group containing a fluorine atom, X,
Y and Z are independently subjected to ink repellent treatment with a treatment agent containing a compound represented by a hydroxyl group, a methyl group, an alkoxy group having 1 to 3 carbon atoms, a chlorine atom, or an isocyanate group). A method for manufacturing a color filter is provided.

Further, there is provided a liquid crystal display device using a color filter formed by those manufacturing methods.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method of manufacturing a color filter according to the present invention, first, a convex portion, preferably a convex portion formed by a black mask, is formed on a substrate in advance. The concave portions separated by the convex portions are made ink-philic by irradiation with energy rays, and then a colored ink is sprayed by an inkjet method to form a colored layer to form a color filter.

FIG. 1 is a sectional view schematically showing a color filter of the present invention. In FIG. 1, 1 is a substrate, 2 is a convex portion, 3 is a concave portion divided by the convex portion and the convex portion, 4 is an upper surface of the convex portion, 5 is a side surface of the convex portion, and 6 is formed by spraying and depositing on the concave portion. 2 shows a colored layer obtained. Only the rightmost concave portion 3 is shown in a state in which the colored layer is not formed for the sake of easy understanding of the description.

Although only four convex portions and three concave portions are shown in this drawing for the sake of clarity, the necessary numbers are provided. For example, in the case of a striped color filter and 640 pixels are required, three color filters of RGB are required for each pixel, so that 1921 convex portions and 1920 concave portions are required. In a liquid crystal display device, a color filter pattern may be formed up to the periphery of a display pixel where no display is performed due to the precision of the gap between the substrates.

In the case of the striped pattern, the convex portion may not be formed in the longitudinal direction, but the periphery of the pixel may be completely surrounded by the convex portion. In particular, in the case of a mosaic color filter, the periphery of a pixel is surrounded by a convex portion.

As the substrate in the present invention, a glass substrate is generally used in terms of heat resistance. Although a transparent substrate is usually used as the substrate, the present invention can be applied to a reflective substrate or a substrate colored white. As the substrate, a substrate which has been subjected to surface treatment for preventing alkali elution, imparting gas barrier properties, or for other purposes may be used as necessary.

In the present invention, the projections for partitioning the colored layer are formed on the substrate in a linear shape or a grid shape. The shape of this convex part is
Thus, the depressed concave portions may correspond to the pixels. For example, when a stripe-shaped color filter is formed, it is formed in a linear shape, and in order to correspond to a square pixel, it is formed in a lattice shape. Since this is appropriately determined by the shape of the pixel, various shapes such as a radial shape and a circumferential shape are also conceivable.

It is advantageous that the convex portion also serves as a black mask in a liquid crystal display device or the like. For this reason, in the following description, a description will be given based on an example in which the convex portion is also used as a black mask.
Then, a black material or a metal light-shielding layer may not be used.

As a method of forming the convex portion by the black mask, for example, a metallic chromium film, a laminated layer of metallic chromium and chromium oxide, or a black layer composed of a black pigment such as carbon black and a resin is formed, and these are formed. There is a method of applying a photoresist, removing the resist in the pixel portion by a photolithography method, and removing a layer of metal chromium or the like by etching. Further, as a more cost-effective method, there is a method in which a black film made of a material containing a black pigment such as carbon black and a photocurable resin is formed, and the black film is patterned into a desired pattern by a photolithography method.

In the present invention, various known black mask forming methods capable of forming a projection having a certain height in a desired pattern can be used. The projection may be formed by laminating a thin black mask and a thick resin layer.

The convex portion in the present invention plays a role of preventing the sprayed ink from flowing into or bleeding into other pixels when colored by the ink jet method. Therefore, it is preferable that the height of the convex portion is high to some extent, but it is also required that the overall flatness of the color filter is high, so that a height close to the thickness of the coloring layer is selected.

Specifically, the amount is usually about 0.1 to 2 μm, though it varies depending on the amount of the deposited ink to be sprayed to obtain a desired color. If ink remains on the upper surface of the convex portion, flatness and uniformity of coloring between pixels are impaired. Therefore, the convex portion should be made ink-repellent, and the concave portion should be made ink-philic to improve ink spreading. preferable.
That is, the protrusion repels ink, and the substrate in the recess enhances ink affinity.

Regarding the degree of the affinity for ink, when a water-based ink is used, it is preferable that the contact angle of the substrate of the recess is 20 ° or less as measured by water. This is 2
If it is larger than 0 °, the spread of ink in the concave portions tends to be poor, and color loss tends to occur in the peripheral portions of the pixels. In particular, it is preferably set to 10 ° or less.

Further, the ink repellency of the convex portion is preferably such that the contact angle of water is 90 ° or more, and it becomes easy to prevent the ink from flowing out to an adjacent pixel or remaining on the convex portion. preferable. Usually, it may be set to about 90 to 120 °.

As a method of imparting ink repellency to the protrusions, it is preferable to use a photosensitive material as the material for forming the protrusions, apply this to glass, and then apply the ink repellent treatment.
In particular, it is preferable to use a treatment agent containing a compound represented by RSiXYZ as the ink repellent treatment agent.

However, R represents a hydrocarbon group containing a fluorine atom, and X, Y and Z each independently represent a hydroxyl group, a methyl group,
It represents an alkoxy group having 1 to 3 carbon atoms, a chlorine atom, or an isocyanate group.

This is due to the four bonds of silicon being R, X,
It has four types of groups Y and Z. More preferably, R- is R ^f -R ¹ - is. Wherein R ^f - is a perfluoroalkyl group, -R ¹ - represents an alkylene group. In particular, -R ¹ - is -CH ₂ CH ₂ - of compounds are preferred. Such a compound generally called a fluorine-containing silane coupling agent or a fluorine-containing isocyanate silane is preferable because it has sufficient ink repellency and adhesiveness to the surface to be treated.

Fluorine-containing isocyanate silanes are particularly suitable because of their high adhesion to the surface to be treated. Also,
In the case of a fluorine-containing silane coupling agent, in order to enhance the reaction and fixing property to the base material, hydrolysis is performed in advance to substitute the terminal alkoxy group with a hydroxyl group or to cause a partial condensation reaction to generate a condensate. It can also be used in the form.

The above R ^f- represents a perfluoroalkyl group in which a hydrogen atom is completely replaced by a fluorine atom, and typical ones are CF _3- , C ₆ F _13- , C ₈ F _17- , C.
₁₀ F ₂₁ -etc. Further, those having a side chain structure can also be used. From the viewpoint of inter alia high water repellency is obtained, C ₈ F ₁₇ - are particularly preferred.

When the ink repellent treatment is performed with these compounds, a method of diluting with a solvent and applying by a method such as spin coating, spray coating, roll coating, die coating, dip coating, and drying is used.

When the ink-repellent treatment is performed in a state where the resin forming the convex portions is uncured, that is, when the ink-repellent treatment is performed before patterning the convex portions, the resin forming the convex portions is not adversely affected. Need to Therefore, perfluorooctane, perfluoro (2-butyltetrahydrofuran), which does not adversely affect the resin forming this convex portion,
It is preferable to use a solvent of a perfluorinated compound such as perfluoro (tributylamine).

It is sufficient that the thickness of the treatment layer of this treatment agent is one molecule to several molecules of the treatment agent.

In the present invention, energy rays are irradiated as a method of making the recesses ink-philic. As a concrete type of energy ray, it is generated by a low-pressure mercury lamp 2
Examples of the ultraviolet light mainly include light having a wavelength of 54 nm. With ultraviolet light of this wavelength, both the convex portion and the concave portion can be made hydrophilic, and the degree of ink repellency can be controlled at the convex portion,
On the other hand, in the concave portion, high hydrophilicity can be obtained. It should be noted that ozone is generated by irradiation with this wavelength, which also contributes to hydrophilization.

Irradiation of these energy rays may be carried out from either the surface side provided with the convex portion of the substrate or the opposite side. When the irradiation is performed from the front side, the convex portion and the concave portion are simultaneously irradiated from the back surface side. In this case, mainly the recesses can be selectively made hydrophilic.
Therefore, by combining the irradiation from the front surface side and the back surface side, it is possible to obtain the necessary hydrophilicity balance between the convex portions and the concave portions. When it is desired to make only the recesses hydrophilic, it is sufficient to irradiate the energy rays only from the surface of the substrate opposite to the surface provided with the projections. This is particularly suitable when the convex portion also serves as the black mask or is laminated with the black mask.

The irradiation dose of these energy rays may be approximately 1000 to 10000 mJ, and may be appropriately experimentally determined so that desired water repellency of the convex portion and hydrophilicity of the concave portion can be obtained depending on the material used. .

Acrylic and polyimide resins are preferred as the polymeric material for forming the protrusions. Further, a black resin may be added to use this as a black mask, and various photosensitive polymers and curing agents may be added to make the resin photosensitive.

In the present invention, the ink jet method is used as a coloring method. As an inkjet method, a method of continuously ejecting charged ink and controlling by an electric field,
Various methods, such as a method of intermittently ejecting ink using a piezoelectric element and a method of intermittently ejecting ink by heating ink and utilizing its foaming, can be adopted.

In the above description, an example in which a hydrophilic ink is used has been described, but the ink used may be oil-based or water-based. However, it is more preferable to use a water-based ink based on water because of the surface tension. The coloring material contained in the ink can use both a dye and a pigment. From the viewpoint of durability, the use of a pigment is more preferable.

In the ink of the present invention, a component which is hardened by heating or hardened by an energy ray such as ultraviolet ray can be added in consideration of the step after coloring. Various thermosetting resins are widely used as components that are cured by heating. In addition, examples of the component that is cured by energy rays include those obtained by adding a photoreaction initiator to an acrylate derivative or a methacrylate derivative.

Particularly, in consideration of heat resistance, an acryloyl group,
Those having a plurality of methacryloyl groups in the molecule are more preferable. As these acrylate derivatives and methacrylate derivatives, water-soluble ones can be preferably used, and even those which are hardly soluble in water can be used after emulsification.

In the present invention, by doing so,
Defects due to ink repelling as shown in FIG. 2 can be reduced. FIG. 2 is a sectional view of a portion surrounded by two convex portions 12 on a substrate 11.
It shows that the ink sprayed on the two recesses was repelled due to the lack of ink affinity of the substrate. That is, when the cissing occurs, the thickness of the colored layer 16 in the peripheral portion tends to be smaller than that in the central portion, and a portion without the colored layer may occur in the peripheral portion of the pixel.

Such unevenness of the colored layer causes color loss of pixels and makes it difficult to obtain a color display with good contrast when used as a display element. On the other hand, according to the present invention, it is easy to obtain a colored layer having a uniform thickness in the concave portions, and it is difficult to cause color loss of pixels and deterioration of contrast.

In the present invention, inks of three colors, RGB, are usually sprayed by the ink jet method to form color filters of three colors. This color filter includes a liquid crystal display element, an electrophoretic display element, an electrochromic display element,
Used as a display element in combination with ZT or the like. It can also be used for applications that use color cameras and other color filters.

FIG. 3 is a schematic cross-sectional view showing an example of use in a liquid crystal display element. In FIG. 3, 21 is a substrate, 22 is a convex portion, 23 is a colored layer, 24 is a flattening layer made of resin or the like covering the surface, 25 is In ₂ O ₃ —SnO _2.
(ITO), electrodes of SnO ₂ or the like, 26 is an alignment film of polyimide, polyamide, SiO or the like, 27 is the other substrate, 28
Is the other electrode, 29 is an alignment film, and 30 is a liquid crystal layer sandwiched between the electrodes.

In addition to the above, in the present invention, if necessary, a polarizing film, a reflecting plate, a retardation plate, a light source, etc. may be arranged outside the liquid crystal cell to be used as a liquid crystal display element.

[0048]

【Example】

Examples 1 and 2 A black colored photoresist (“V-259BK” manufactured by Nippon Steel Chemical Co., Ltd.) was applied to a glass substrate by a spin coating method so as to have a target film thickness of 1.5 μm, and the photoresist was applied at 80 ° C. for 5 minutes.
Heated for minutes. _{C 8 F 17 -C 2 H 4} -Si (-OC
H _{3) 3} (Toshiba Silicone Co., Ltd. "TSL-8233")
Was diluted with methanol and some water was added.

After allowing this to stand overnight, perfluoro (2
-Butyltetrahydrofuran) to extract the active ingredient,
It was diluted to 0.25% by weight, applied on the photoresist film by spin coating, and heated at 100 ° C. for 5 minutes. This substrate is exposed to 100 mJ through a photomask, dipped in a designated developer for 30 seconds, washed with cold water, and post-cured at 230 ° C. for 1 hour. It also serves as a black mask and has a height of about 1.5 μm and a width. A substrate having a convex portion of about 30 μm was obtained.

In Example 1, the substrate was irradiated with ultraviolet rays of 1500 mJ from the surface on which the convex portion was provided and 2500 mJ from the surface on the opposite side by the low pressure mercury lamp. In Example 2, 4000 m from the surface opposite to the surface provided with the convex portion by the low pressure mercury lamp.
The ultraviolet ray of J was irradiated.

The concave portions surrounded by the convex portions of these substrates were sprayed with a water-based pigment ink by an ink jet method to obtain striped RGB color filters. Table 1 shows the results.

Comparative Example 1 A color filter was formed in the same manner as in Example 1 except that the energy rays were not irradiated. Table 1 shows the results.

[0053]

[Table 1]

In the results shown in Table 1, "○" means that there were no such defects (good products), and "X" means that those defects occurred (defective products). In addition,
“⊚” indicates that the flatness of the colored layer is higher than that of “∘”.

In both Examples 1 and 2, defects such as ink outflow to the adjacent concave portion, color loss in the peripheral portion of the pixel, and color unevenness in the pixel did not occur. Particularly, in Example 1, the flatness of the colored layer in the pixel was high. On the other hand, in the case of the comparative example, since the ink does not spread sufficiently in the pixel, there is a place where color loss occurs in the peripheral portion of the pixel, and the thickness of the coloring layer is thick in the center of the pixel, and color unevenness in the pixel considerably occurs. It was

Example 3, Comparative Example 2 Pixels of Example 1 were dot-shaped and surrounded by the convex portions in the same manner as in Example 1 except that convex portions were provided so that the RGB pixels were in a mosaic arrangement. The recesses were sprayed with an aqueous pigment ink by an inkjet method to obtain an RGB color filter having a mosaic arrangement. Similarly, as a comparative example, a color filter was formed in the same manner as in Example 2 except that the energy ray irradiation was not performed.

Similar to the color filter of the first embodiment, the color filter of the third embodiment did not cause defects such as ink outflow to the adjacent concave portion, color loss in the peripheral portion of the pixel, and color unevenness in the pixel. On the other hand, in Comparative Example 2, Comparative Example 1
Performance is worse than that, and there is a place where color loss occurs in the pixel peripheral part because ink does not spread sufficiently in the pixel,
The color unevenness in the pixel was considerably generated.

Example 4 C ₈ F ₁₇ -C ₂ H ₄ -Si (-NC) of the ink repellent treatment agent
O) ₃ with perfluoro (tributylamine) 0.05
A color filter was formed in the same manner as in Example 1 except that the color filter was used after diluting to a weight percentage. Similar to Example 1, this color filter did not cause defects such as outflow to the adjacent concave portion, color loss in the peripheral portion of the pixel, and color unevenness in the pixel.

A flattening layer of resin was formed on the color filter of Example 1, ITO was formed, and the ITO was patterned, and further, an alignment film of resin was formed and rubbed to form a first substrate. Next, ITO was formed on a glass substrate, which was patterned, a resin alignment film was formed, and rubbing was performed to form a second substrate. The first substrate and the second substrate were arranged so that the electrode surfaces face each other, and the periphery was sealed to form an empty cell.

Injecting nematic liquid crystal into this empty cell,
The inlet was sealed to form a liquid crystal cell. A phase difference plate and a polarizing plate were arranged on both sides of the liquid crystal cell to manufacture an FSTN type liquid crystal display device. This liquid crystal display device was capable of displaying beautiful colors.

[0061]

According to the present invention, when a color filter is manufactured by spraying ink by an ink-jet method having good productivity, the ink hardly adheres to the convex portion and the ink spreads well in the concave portion. This has the effect that color omission is less likely to occur in the pixel. This can improve display performance as a liquid crystal display element.

Furthermore, by performing the ink-affinity treatment by irradiating energy rays from the surface opposite to the side on which the protrusions are provided, the ink-repellency of the protrusions is not significantly impaired, and the ink-reduction of the recesses is easy. Therefore, productivity is good.

If the ink repellency of the convex portion is too high, the thickness of the colored layer tends to decrease in the peripheral portion of the pixel depending on the ink used and the degree of ink affinity of the concave portion. In the present invention, the energy rays are irradiated from both sides of the substrate, the ink repellency of the convex portions is slightly lowered, and the ink repellency of the concave portions is balanced to further improve the flatness in the pixel. You can also let it. The present invention can be applied to various applications within a range that does not impair the effects of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a color filter of the present invention.

FIG. 2 is a schematic cross-sectional view showing a state when ink is sprayed in a conventional example.

FIG. 3 is a schematic cross-sectional view of a liquid crystal display device using the color filter of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiro Tanuma 1150 Hazawa-machi, Kanagawa-ku, Yokohama-shi, Kanagawa Asahi Glass Co., Ltd. Central Research Laboratory

Claims (7)

[Claims] 1. A method of manufacturing a color filter, comprising forming a convex portion on a base material, spraying ink by an ink jet method on the concave portion divided by the convex portion, and depositing the ink in the concave portion to form a colored layer. A method for producing a color filter, characterized in that, after forming a convex portion, the ink affinity of the concave portion is controlled by irradiating an energy ray, and then the ink is sprayed by an inkjet method. 2. The contact angle of water in the recesses is set to 20 ° or less by the process of irradiating with energy rays.
A method for producing the color filter according to the above. 3. The method of manufacturing a color filter according to claim 1, wherein the convex portion also serves as a black mask. 4. The method for producing a color filter according to claim 1, 2 or 3, wherein the energy rays are irradiated from the surface of the substrate opposite to the surface on which the convex portions are formed. 5. An energy ray is irradiated from both sides of the substrate, and the respective irradiation amounts are controlled so that the ink repellency of the convex portion and the ink affinity of the concave portion have desired values. Three
A method for producing the color filter according to the above. 6. The surface of the convex portion is RSiXYZ (R represents a hydrocarbon group containing a fluorine atom, X, Y and Z are each independently a hydroxyl group, a methyl group, an alkoxy group having 1 to 3 carbon atoms, The method for producing a color filter according to claim 1, wherein the ink repellent treatment is performed with a treatment agent containing a compound represented by a chlorine atom or an isocyanate group. 7. A liquid crystal display device using a color filter formed by the manufacturing method according to claim 1.