JP4432353B2 - COLOR FILTER, ITS MANUFACTURING METHOD, AND LIQUID CRYSTAL DEVICE USING COLOR FILTER - Google Patents

Description

【００４９】
【発明の効果】
以上説明したように、本発明によれば、隔壁で囲まれた領域内にインクを付与する際に、隣接する着色部間での混色を防止し、且つ、該領域内でインクを十分に拡散、濃度を向上させて白抜けのない着色部を形成することができる。すなわち、混色、白抜け、色ムラのない着色部を備えた信頼性の高い光学素子をインクジェット方式により簡易なプロセスによって歩留まり良く製造することができる。よって、上記カラーフィルタを用いて、カラー表示特性に優れた液晶素子をより安価に提供することができる。
【００５０】
【図面の簡単な説明】
【図１】本発明の製造方法の一実施形態を示す工程図である。
【図２】本発明の液晶素子の一実施形態の断面図である。
【符号の説明】
１ 光透過性基板
２ 遮光性樹脂組成物層
３ ブラックマトリクス
４ 開口部
５ インクジェットヘッド
６ａ〜６ｃ 着色インク
７ａ〜７ｃ 下塗り層
８ａ〜８ｃ 着色部
９ 保護膜
１０ 光透過性基板
１１ａ、１１ｂ 電極
１２ａ、１２ｂ 配向膜
１３ 液晶
１４ａ、１４ｂ 偏光板
１５ 光[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color filter for a display device such as a field emission display device, a fluorescent display device, a plasma display (PDP) and a liquid crystal display device using an ink jet recording technique, a manufacturing method thereof, and a liquid crystal element using the color filter. .
[0002]
[Prior art]
In recent years, a method for producing a color filter using an ink jet method has been studied mainly for the purpose of cost reduction (see Patent Document 1). However, when creating a color filter by the ink jet method, there are particularly problems specific to the ink jet method, such as “mixed color”, “white spot”, and “color unevenness”.
[0003]
In the manufacturing method of the color filter in which the black matrix is used as a partition and ink is applied to the opening of the black matrix to form a colored portion, the volume is several to several tens of times the volume of the opening of the black matrix. It is necessary to apply an ink having If the solid content concentration of the colorant or curing component contained in the ink is high, that is, if the volume of the applied ink is relatively small, the black matrix functions sufficiently as a partition wall, and the inside of the opening of the black matrix Ink can be retained. Therefore, the applied ink does not go over the black matrix and reach the adjacent colored portions of different colors.
[0004]
However, in order to eject ink more stably from the inkjet head nozzle, it is necessary to lower the viscosity, that is, the solid content concentration in the ink must be lowered. In this case, it is necessary to apply a large amount of ink to form the colored portion. At this time, since the ink overflows beyond the black matrix serving as the partition wall, “color mixing” occurs between the adjacent colored portions.
[0005]
In recent years, in color filters for TFT-type liquid crystal elements, the shape of the opening of the black matrix has become complicated in order to protect the TFT from external light or to obtain a bright display by increasing the aperture ratio. ing. For this reason, there are a plurality of corner portions, and when the solid content in the ink is high, there arises a problem that the ink does not sufficiently diffuse into the corner portions. In forming a black matrix, a photolithography process using a resist is generally used. Contaminants may adhere to the surface of the transparent substrate due to various components contained in the resist, which may hinder ink diffusion.
[0006]
This is a problem called “white spot”. The white spots cause display defects such as color unevenness and contrast reduction.
[0007]
[Patent Document 1]
JP 59-75205 A (Fig. 3)
[0008]
[Problems to be solved by the invention]
The object of the present invention is to solve the problems inherent to the ink jet system such as “color mixing”, “white spot”, and “color unevenness” when manufacturing a color filter at a low cost by a simple process using the ink jet system. The object is to provide a high color filter with high yield.
[0009]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a color filter for forming a black matrix having a square opening on at least a light-transmitting substrate and a colored portion having a colored ink applied to the opening of the black matrix by an ink jet method. In the manufacturing method, a step of applying the colored ink to the opening so as to have a thickness of 20 to 30% when dried with respect to the thickness of the opening of the black matrix, and curing the colored ink Forming a colored portion by a step of forming an undercoat layer, a step of overcoating the colored ink on the undercoat layer, and a step of curing the overcolored colored ink . It is a manufacturing method.
The invention according to claim 2 is the method for producing a color filter according to claim 1, wherein the black matrix has a thickness of 0.5 to 2.0 μm and an aperture ratio of 60% or more.
According to a third aspect of the present invention, in the color ink according to the first aspect, the colored ink is obtained by dispersing a pigment in an organic solvent at a concentration of at least 10% or more with respect to the total weight of the ink. It is a manufacturing method of a filter.
The invention according to claim 4 is characterized in that, in the step of forming the undercoat layer, after the colored ink is applied, the colored ink is temporarily cured by performing a heat treatment at 70 ° C. for 20 minutes. The manufacturing method of the color filter in any one of Claim 1 or Claim 3.
The invention according to claim 5 is characterized in that, in the step of forming the colored portion, after the colored ink is overcoated, a heat treatment is performed at 230 ° C. for 1 hour to cure the colored ink. It is a manufacturing method of the color filter in any one of Claim 1 or Claim 3.
The invention according to claim 6 is the method for producing a color filter according to claim 1 or 3 , wherein the colored ink is cured by any one of heat, light, and electron beam.
A seventh aspect of the present invention is a color filter manufactured by the manufacturing method according to the first to sixth aspects.
The invention according to claim 8 is a liquid crystal element characterized in that a liquid crystal is sandwiched between the color filter according to claim 7 and a counter substrate.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a process diagram showing an embodiment of the production method of the present invention. Hereinafter, (a) to (g) in FIG. 1 are cross-sectional views corresponding to the following steps (a) to (g).
[0011]
[Step (a)]
A light transmissive substrate 1 is prepared. In the present invention, a glass substrate is generally used as the light-transmitting substrate. However, the glass substrate should satisfy the characteristics required for the final use such as a liquid crystal display device, such as transparency and mechanical strength, and can withstand subsequent processes. For example, the substrate is not limited to a glass substrate, and plastic substrates such as polyethylene terephthalate (PET), polyethersulfone (PES), and polyethylene naphthalate (PEN) can also be used.
[0012]
[Step (b)]
A light-shielding resin composition layer 2 for forming a black matrix 3 is formed on the light transmissive substrate 1. The light-shielding resin composition layer 2 is finally used as a black matrix and needs to have sufficient light-shielding properties. Therefore, a black resin composition in which a light shielding agent is dispersed in the resin composition is used. As the light-shielding agent, it is desirable to use carbon black, and the carbon black is manufactured by a contact method called channel black, roller black, or disk black, gas furnace black, oil furnace black. It is possible to use those manufactured by the furnace method called thermal black, thermal black, those manufactured by the thermal method called acetylene black, etc., especially channel black, gas furnace black, oil Furnest black is preferred. If necessary, a mixture of R, G, and B pigments may be added. Moreover, the black resist generally marketed can also be used. If necessary, a light-shielding layer with a high resistance may be used. Further, the black matrix 3 preferably has a thickness of at least about 0.5 to 2.0 .mu.m because it functions as a light-blocking property and also serves as a partition wall for preventing ink from leaking to the adjacent colored portion when ink is applied. In order to obtain a clearer image, an aperture ratio of 60% or more is required.
[0013]
Moreover, as a material of the light-shielding resin composition layer 2, a photosensitive resin material such as an epoxy resin, an acrylic resin, a polyimide resin including a polyamideimide, a urethane resin, a polyester resin, or a polyvinyl resin is used. However, it is preferable to have a heat resistance of 250 ° C. or higher, and from this point, an epoxy resin, an acrylic resin, and a polyimide resin are preferably used.
[0014]
The light-shielding resin composition layer 2 can be formed by a method such as spin coating, roll coating, bar coating, spray coating, dip coating, die coating, or printing.
[0015]
[Step (c)]
A black matrix 3 is formed by patterning the light-shielding resin composition layer 2 by performing pattern exposure and development using a photomask.
[0016]
[Step (d)]
Using an inkjet recording apparatus, R, G, and B inks 6a to 6c are undercoated (referred to as an undercoat layer) from the inkjet head 5 to the openings 4 of the black matrix 3. Undercoating is a state in which the inks 6a to 6c are wet and spread over the entire surface of the opening, and refers to applying an ink amount of about 30% with respect to the depth of the opening.
[0017]
In the present invention, as the color ink used for forming the color filter, both dye-based and pigment-based inks can be used. Further, it is a curable ink containing a component that is cured by heat treatment or irradiation with light, electron beam, etc. and immobilizes a dye or pigment used as an ink colorant, that is, a component such as a crosslinkable monomer or polymer. Is preferred. As the main component of the ink, both water and an organic solvent can be used, but an organic solvent is preferred from the viewpoint of volatility, solubility, applicability, dispersion stability, and the like. As the solvent, toluene, xylene, ethyl cellosolve, ethyl cellosolve acetate, diclime, cyclohexanone, and the like are used. The solvent is selected from coating properties, dispersion stability, etc., and a solvent having a single or plural solvent composition is appropriately selected. Further, when a pigment is used as the colorant of the ink, it is preferable that the ratio of the pigment is at least 10% or more based on the total weight of the ink in order to achieve a predetermined concentration.
[0018]
Furthermore, as an ink jet method, a bubble jet (registered trademark) type using an electrothermal transducer as an energy generating element or a piezo jet type using a piezoelectric element can be used, and the coloring area and coloring pattern can be arbitrarily set. Can be set.
[0019]
[Step (e)]
Undercoat layers 7a to 6c are prepared by subjecting the inks 6a to 6c of R, G, and B, which have been undercoated, to heat treatment or necessary treatment such as light and electron beam irradiation, and removing and curing the solvent components in the inks 6a to 6c. 7c is formed. As a result, the concentration in the undercoat layer increased.
[0020]
[Step (f)]
Again, the ink 6a-6c of each color of R, G, and B is applied from the opening part 4 of the black matrix 3, ie, undercoat layer 7a-7c, using the inkjet head 5. FIG.
[0021]
As described above, the same ink as the ink on which the undercoat layer is formed is further applied on the undercoat layer, so that the ink is sufficiently and uniformly diffused in the region (opening 4) surrounded by the partition walls. Can do. That is, the “white spot” problem is solved, and a color filter substrate free from “color unevenness” can be obtained. By further repeating the above steps (d) to (f), the density in the colored layer increases, and the problems of “white spots” and “color unevenness” are further solved.
[0022]
[Step (g)]
Colored portions (pixels) 8a to 8c are formed by performing necessary processing such as heat treatment or light irradiation, and removing and curing the solvent components in the inks 6a to 6c.
[0023]
Further, a protective layer 9 and a transparent conductive film are formed as necessary. As the protective layer in this case, a photocuring type, a thermosetting type, or a photothermal combination curing type resin material, or an inorganic film formed by vapor deposition, sputtering, or the like can be used. Any material can be used as long as it has transparency and can withstand a subsequent transparent conductive film formation process, alignment film formation process, and the like. Moreover, you may form a transparent conductive film directly, without passing through a protective layer.
[0024]
FIG. 2 shows a cross-sectional view of an embodiment of a liquid crystal element using the color filter substrate of the present invention. In the figure, 10 is a light-transmitting substrate similar to the substrate 1, 11a and 11b are electrodes, 12a and 12b are alignment films, 13 is a liquid crystal, and 14a and 14b are polarizing plates. The present embodiment is an active matrix type liquid crystal element using a TFT (not shown).
[0025]
A method for manufacturing the liquid crystal element of FIG. 2 will be described. A (common) electrode 11b and an alignment film 12b are formed on the protective film 9 of the color filter substrate described above. On the other hand, TFTs (not shown) and (pixel) electrodes 11a are formed in a matrix on the opposing substrate 10, and an alignment film 12a is further formed thereon. These substrates are arranged to face each other so that the colored portions 8a to 8c of the color filter are arranged at positions facing the pixel electrodes 11a, and are bonded through a sealing material, and the liquid crystal compound 13 is filled in the gaps. The liquid crystal element shown in FIG. 2 is configured. The surfaces of the alignment films 12a and 13b are usually subjected to an alignment process such as a rubbing process, whereby liquid crystal molecules can be aligned in a certain direction.
[0026]
Further, polarizing plates 14a and 14b are bonded to the outside of the substrates 1 and 10, respectively.
[0027]
A combination of a fluorescent lamp and a scattering plate (not shown) is generally used as the backlight, and the liquid crystal element is displayed by functioning as an optical shutter that changes the transmittance of the light 15 of the backlight. To do.
[0028]
The liquid crystal compound used in the present invention is not particularly limited, and TN liquid crystal, ferroelectric liquid crystal (FLC) and the like are preferably used. Further, the present invention is not limited to the active matrix liquid crystal element described in the above embodiment, and a simple matrix liquid crystal element can also be configured, for example.
[0029]
Further, the color filter substrate of the present invention can be suitably used in addition to the liquid crystal element.
[0030]
【Example】
A black resist (“V-259BK resist” manufactured by Nippon Steel Chemical Co., Ltd.) containing carbon black was formed on a glass substrate (Corning, product number 7059) by a spin coater to a coating thickness of about 1.5 μm. Furthermore, predetermined exposure, development, and baking processes were performed, and a black matrix pattern (partition) having a square opening with a line width of 20 μm and 100 μm × 100 μm and an aperture ratio of 60% was produced.
[0031]
(Colored ink adjustment)
For red ink, acrylic resin (20 parts by weight of methacrylic acid, 15 parts by weight of hydroxyethyl methacrylate, 10 parts by weight of methyl methacrylate, 55 parts by weight of butyl methacrylate was dissolved in 300 parts by weight of ethyl cellosolve, and azobis was added under a nitrogen atmosphere. Acrylic resin obtained by adding 0.75 parts by weight of nitrile and reacting at 70 ° C. for 5 hours was diluted with ethyl cellosolve so that the resin concentration was 20% by weight. 90.1 g of this diluted resin, red pigment chromophthal red A2B (C, I, Pig Red 177 65300: manufactured by Ciba Gaiky) 6.95 g, yellow pigment Paliotol Yellow L1820 (C, I, Pig Yellow 139: manufactured by BASF) 2.05 g and 0.9 g of a dispersant were added and dispersed for 3 hours without cooling with a bead mill disperser. Ethyl cellosolve was used as a solvent, diluted to have a viscosity of 5 cp or less, and stirred well to prepare a red ink.
[0032]
For green ink, acrylic resin (20 parts by weight of methacrylic acid, 15 parts by weight of hydroxyethyl methacrylate, 10 parts by weight of methyl methacrylate, 55 parts by weight of butyl methacrylate was dissolved in 300 parts by weight of ethyl cellosolve, and azobis was added under a nitrogen atmosphere. Acrylic resin obtained by adding 0.75 parts by weight of nitrile and reacting at 70 ° C. for 5 hours was diluted with ethyl cellosolve so that the resin concentration was 20% by weight. 90.1 g of this diluted resin, green pigment Lionol Green 2YS (C, I, Pig Green 36: manufactured by Toyo Ink Manufacturing Co., Ltd.) 7.55 g, yellow pigment Paliotol Yellow L1820 (C, I, Pig Yellow 139: BASF Corporation) 1.45 g and 0.9 g dispersant were added and dispersed for 3 hours without cooling with a bead mill disperser. The solution was diluted with ethyl cellosolve as a solvent so that the viscosity was 5 cp or less, and stirred well to prepare a green ink.
[0033]
For blue ink, acrylic resin (20 parts by weight of methacrylic acid, 15 parts by weight of hydroxyethyl methacrylate, 10 parts by weight of methyl methacrylate, 55 parts by weight of butyl methacrylate was dissolved in 300 parts by weight of ethyl cellosolve, and azobis was added under a nitrogen atmosphere. Acrylic resin obtained by adding 0.75 parts by weight of nitrile and reacting at 70 ° C. for 5 hours was diluted with ethyl cellosolve so that the resin concentration was 20% by weight. 91 g of this diluted resin, 0.8 g of blue pigment heliogen blue L6700F (manufactured by BASF), 0.1 g of purple pigment ryonogen violet RL (manufactured by Toyo Ink) and 0.9 g of a dispersant were added to disperse the bead mill. It was dispersed for 3 hours while cooling with a machine. A blue ink was prepared by diluting with ethyl cellosolve as a solvent to a viscosity of 5 cp or less and stirring well.
[0034]
Next, using a piezo method and an inkjet recording apparatus equipped with a head having a nozzle resolution of 180 dpi, R, G, and B pigment dispersion inks prepared by the method described above were applied to the openings of the matrix-shaped light shielding layer on the glass substrate. . At this time, the amount of applied ink was adjusted to a height of about 20 to 30% at the stage of drying with respect to the thickness of the opening of the matrix light shielding layer. After applying the ink, a heat treatment was performed at 70 ° C. for 20 minutes to temporarily cure the ink, thereby forming an undercoat layer composed of R, G, and B colored portions.
[0035]
Next, using the inkjet recording apparatus, the R, G, and B inks are overcoated on the black matrix opening (undercoat layer), and heat-treated at 230 ° C. for 1 hour to cure the ink. A color filter composed of colored portions of R, G, and B was formed.
[0036]
Further, a two-component thermosetting resin SS-7625 (manufactured by JSR) was spin-coated as a protective film so as to have a film thickness of 1 μm, and cured by heat treatment at 230 ° C. for 1 hour.
[0037]
When the color filter substrate for a liquid crystal element thus prepared was observed with an optical microscope, neither color mixing nor white spots were observed. Also, the concentration was high. Moreover, when the flatness of each coloring part was observed, each coloring part was formed substantially flat. The color difference (■ Eab) between the colored portions was as good as 3 or less, and a highly reliable color filter could be produced.
[0038]
The display characteristics of the liquid crystal element in which the liquid crystal is sandwiched between the color filter and the opposing substrate (active matrix TFT) were good.
[0039]
(Comparative Example 1)
A black matrix is formed on a glass substrate in the same manner as in the example, and an undercoat layer is not provided. The same amount of ink as in the example is applied to the opening to form a colored portion in one step, and a color filter is produced. did.
[0040]
Further, a two-component thermosetting resin SS-7625 (manufactured by JSR) was spin-coated as a protective film so as to have a film thickness of 1 μm, and cured by heat treatment at 230 ° C. for 1 hour.
[0041]
When the color filter substrate for a liquid crystal element thus prepared was observed with an optical microscope, as a result of applying a large amount of ink, the ink overflowed from the opening, and each colored portion was overlapped and mixed, resulting in good color. A patterned colored layer was not formed.
[0042]
The display characteristics of the liquid crystal element in which the liquid crystal is sandwiched between the color filter and the counter substrate (active matrix TFT) are not preferable.
[0043]
(Comparative Example 2)
In the same manner as in the example, a black matrix was formed on a glass substrate, and the same amount of ink as in the case of providing an undercoat layer was applied to the opening to form a colored portion, thereby producing a color filter.
[0044]
Further, a two-component thermosetting resin SS-7625 (manufactured by JSR) was spin-coated as a protective film so as to have a film thickness of 1 μm, and cured by heat treatment at 230 ° C. for 1 hour.
[0045]
When the color filter substrate for a liquid crystal element thus prepared was observed with an optical microscope, no color mixture was confirmed, but white spots were confirmed due to an insufficient amount of applied ink. Further, since the formed film thickness was thin, the density was lower than that of the example, and the color difference (■ Eab) with the current color filter was 10 or more, and a good color filter was not formed.
[0046]
Further, when the flatness of each colored portion was observed, the flatness of each colored portion was poor and the color difference (■ Eab) was 10 or more.
[0047]
The display characteristics of the liquid crystal element in which the liquid crystal is sandwiched between the color filter and the counter substrate (active matrix TFT) are not preferable.
[0048]
[Table 1]

[0049]
【The invention's effect】
As described above, according to the present invention, when ink is applied to the area surrounded by the partition walls, color mixing between adjacent colored portions is prevented, and ink is sufficiently diffused within the area. The density can be improved to form a colored portion without white spots. That is, a highly reliable optical element having a colored portion free from mixed colors, white spots, and color unevenness can be manufactured by a simple process with a high yield using an inkjet method. Therefore, a liquid crystal element having excellent color display characteristics can be provided at a lower cost by using the color filter.
[0050]
[Brief description of the drawings]
FIG. 1 is a process chart showing an embodiment of a production method of the present invention.
FIG. 2 is a cross-sectional view of an embodiment of the liquid crystal element of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Light transmissive board | substrate 2 Light-shielding resin composition layer 3 Black matrix 4 Opening part 5 Inkjet head 6a-6c Colored ink 7a-7c Undercoat layer 8a-8c Colored part 9 Protective film 10 Light transmissive board | substrates 11a, 11b Electrode 12a, 12b Alignment film 13 Liquid crystal 14a, 14b Polarizing plate 15 Light

Claims (8)

At least a black matrix on a light transmissive substrate ,
In the manufacturing method of the color filter that forms the colored portion by applying the colored ink to the opening of the black matrix by the inkjet method,
Forming a black matrix having a square opening on the light transmissive substrate;
Undercoating the colored ink in the opening of the black matrix;
A step of curing the colored ink and forming an undercoat layer having a thickness of 20 to 30% when dried with respect to the thickness of the opening of the black matrix;
A step of repeatedly applying the colored ink on the undercoat layer;
Curing the overlying colored ink to form a colored portion;
A method for producing a color filter, comprising: The method for producing a color filter according to claim 1, wherein the black matrix has a thickness of 0.5 to 2.0 μm and an aperture ratio of 60% or more. 2. The method for producing a color filter according to claim 1, wherein the colored ink is obtained by dispersing a pigment in an organic solvent at a concentration of at least 10% or more based on the total weight of the ink. 4. The method according to claim 1, wherein, in the step of forming the undercoat layer, after the colored ink is applied, the colored ink is temporarily cured by performing a heat treatment at 70 ° C. for 20 minutes. The manufacturing method of the color filter of description. 4. In the step of forming the colored portion, after the color ink is overcoated, heat treatment is performed at 230 ° C. for 1 hour to cure the color ink. The manufacturing method of the color filter of description. The method for producing a color filter according to claim 1, wherein the colored ink is cured by any energy of heat, light, and electron beam. A color filter manufactured by the manufacturing method according to claim 1. A liquid crystal element comprising a liquid crystal sandwiched between the color filter according to claim 7 and a counter substrate.

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