JP2004117537A - Color filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color filter which is free of disorder of alignment of liquid crystal and a shift in threshold of switching due to singular electric characteristics of a transverse electric field type liquid crystal display device, i.e. exerts no adverse influence on display performance. <P>SOLUTION: The dielectric tangent tanδ of two layers configured by laminating an overcoat layer on a color layer of Green pixels is ≤0.05 in a frequency range of 20 Hz to 1 MHz. Further, the specific dielectric constant of the two layers configured by laminating the overcoat layer on the color layer of Green pixels is ≤5.0 in a frequency range of 20 Hz to 1 MHz. <P>COPYRIGHT: (C)2004,JPO

Description

【００５４】
【表２】

【００５５】
実施例１、実施例２、および比較例１のカラーフィルタのＧｒｅｅｎ（緑）画素の色層に透明樹脂によるオーバーコート層を積層した２層の誘電正接ｔａｎδを図３に示す。実施例１および実施例２は２０Ｈｚ〜１ＭＨｚの領域で誘電正接ｔａｎδが０．０５以下であるのに対し、比較例１では５０００ｋＨｚ付近から０．０５以上となり１ＭＨｚでは０．１に達していた。
【００５６】
また、実施例１、実施例２、および比較例１のカラーフィルタのＧｒｅｅｎ（緑）画素の色層にオーバーコート層を積層した２層の比誘電率を図４に示す。尚、図４において、実施例１の数値は、実施例２の数値と近似しているのでプロットした表記はしていない。
実施例１、および実施例２は２０Ｈｚ〜１ＭＨｚの全域で色層とオーバーコート層の２層は５．０以下であるのに対し、比較例１では、２０Ｈｚ付近で５．０以上であった。
【００５７】
得られた実施例１、実施例２、および比較例１のカラーフィルタを用い、各々横電界方式の液晶表示装置を作成したところ、実施例１、および実施例２のカラーフィルタを用いた液晶表示装置においては、液晶の駆動信号の矩形波の立上り、立下りの形状をなまらせ、駆動電圧の閾値ずれを発生させることが少なくなり、表示性能に優れた横電界方式の液晶表示装置が得られた。
尚、比較例１のカラーフィルタを用いた液晶表示装置においては、表示性能の改善は見られなかった。
【００５８】
【発明の効果】
本発明は、Ｇｒｅｅｎ（緑）画素の色層にオーバーコート層を積層した２層の誘電正接ｔａｎδが、周波数２０Ｈｚ〜１ＭＨｚの範囲で０．０５以下のカラーフィルタであるので、横電界方式の液晶表示装置に用いた際に、特異な電気的特性に起因する液晶の配向乱れや、スイッチングの閾値のずれもない、すなわち、表示性能に悪影響を与えないカラーフィルタとなる。
【００５９】
また、本発明は、Ｇｒｅｅｎ（緑）画素の色層にオーバーコート層を積層した２層の比誘電率が、周波数２０Ｈｚ〜１ＭＨｚの範囲で５．０以下のカラーフィルタであるので、横電界方式の液晶表示装置に用いた際に、特異な電気的特性に起因する液晶の配向乱れや、スイッチングの閾値のずれもない、すなわち、表示性能に悪影響を与えないカラーフィルタとなる。
【図面の簡単な説明】
【図１】カラーフィルタの色層と透明樹脂によるオーバーコート層を積層した２層の２０Ｈｚ〜１ＭＨｚでの誘電正接ｔａｎδの値を示すグラフである。
【図２】カラーフィルタのＲｅｄ（赤）、Ｇｒｅｅｎ（緑）、Ｂｌｕｅ（青）の各色層に透明樹脂によるオーバーコート層を積層した２層の２０Ｈｚ〜１ＭＨｚでの誘電正接ｔａｎδの値を示すグラフである。
【図３】実施例１、実施例２、および比較例１のカラーフィルタのＧｒｅｅｎ画素の色層に透明樹脂によるオーバーコート層を積層した２層の２０Ｈｚ〜１ＭＨｚでの誘電正接ｔａｎδの値を示すグラフである。
【図４】実施例１、実施例２、および比較例１のカラーフィルタのＧｒｅｅｎ画素の色層に透明樹脂によるオーバーコート層を積層した２層の２０Ｈｚ〜１ＭＨｚでの比誘電率の値を示すグラフである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a color filter for a liquid crystal display device, and more particularly to a color filter in which the electrical properties of a color layer and an overcoat layer of a color filter do not adversely affect the switching performance of a liquid crystal.
[0002]
[Prior art]
2. Description of the Related Art Color liquid crystal display devices are rapidly spreading mainly in computer terminal display devices and television image display devices. A color filter is an important component that is indispensable for a color display of a liquid crystal display device. In recent years, there has been a high demand for higher image quality of this liquid crystal display device, and various new types of liquid crystal display devices having a high viewing angle and high-speed responsiveness have appeared. Among them, the in-plane switching (IPS) method is expected to be widely used because of its excellent display quality such as viewing angle and contrast ratio.
[0003]
However, the liquid crystal used in the IPS type liquid crystal display device has excellent characteristics such as being able to be driven at a low voltage, but the electrical characteristics of members such as a color filter inherent in the liquid crystal display device. Therefore, there is a problem that the performance is easily deteriorated. In fact, in a conventional liquid crystal display device using a color filter, various display defects have occurred due to disturbance of the alignment of the liquid crystal due to the unique electric characteristics of the color filter pixel and a shift in switching threshold. The unique electrical characteristics of the color filter mainly depend on the properties of the pigment, and it has been considered difficult to solve the problem with the conventional color filter.
[0004]
[Problems to be solved by the invention]
The present invention has been made in order to solve the above-described problems, and there is no alignment disorder of liquid crystal due to the above-described specific electric characteristics in a horizontal electric field type liquid crystal display device, and there is no shift in switching threshold, that is, It is another object of the present invention to provide a color filter that does not adversely affect display performance.
[0005]
[Means for Solving the Problems]
The present invention relates to a color filter for a color liquid crystal display device having an overcoat layer made of a transparent resin, wherein a dielectric tangent tan δ of two layers in which an overcoat layer is laminated on a color layer of a green (green) pixel is in a frequency range of 20 Hz to 1 MHz. Is not more than 0.05.
[0006]
Further, the present invention is the color filter according to the above invention, wherein the dielectric layer has a dielectric loss tangent tan δ of 0.05 or less in a frequency range of 20 Hz to 1 MHz.
[0007]
Further, the present invention is the color filter according to the above invention, wherein the dielectric loss tangent tan δ of the overcoat layer is 0.05 or less in a frequency range of 20 Hz to 1 MHz.
[0008]
Further, the present invention provides a color filter for a color liquid crystal display device having an overcoat layer made of a transparent resin, wherein the relative permittivity of two layers obtained by laminating the overcoat layer on the color layer of a Green pixel is 20 Hz to 1 MHz. In the range of 5.0 or less.
[0009]
Further, the present invention is the color filter according to the above invention, wherein a relative permittivity of a color layer of the green (green) pixel is 5.0 or less in a frequency range of 20 Hz to 1 MHz.
[0010]
Further, the present invention is the color filter according to the present invention, wherein the relative permittivity of the overcoat layer is 5.0 or less in a frequency range of 20 Hz to 1 MHz.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a color filter according to the present invention will be described in detail based on an embodiment.
The inventor of the present invention has conducted various studies on the relationship between the electrical properties of the color filters and display defects. As a result, it was found that the dielectric characteristics of a green (green) pixel are different from those of other colors mainly due to a liquid crystal alignment defect and a switching threshold shift. Found out what is happening. More specifically, the following mechanism is used.
[0012]
FIG. 1 shows two typical dielectric loss tangents tan δ when a color layer of a color filter and an overcoat layer made of a transparent resin are laminated.
The dielectric loss tangent tan δ is an index of the energy consumed in the dielectric. In a horizontal electric field type color liquid crystal display device, a color layer and an overcoat layer of a color filter, which is a dielectric, are inherent in a liquid crystal driving electric field. When a dielectric is placed in an electric field, the energy of the electric field is consumed according to the value of the dielectric loss tangent tan δ of the dielectric, so that the electric field is weakened.
[0013]
Therefore, in the color liquid crystal display device of the horizontal electric field type, a phenomenon that the liquid crystal driving electric field does not have the intended strength may occur depending on the magnitude of the dielectric loss tangent tan δ of the color layer and the overcoat layer of the color filter. Therefore, the dielectric loss tangent tan δ of the color layer and the overcoat layer of the color filter is an important characteristic that determines the display characteristics of the lateral electric field type color liquid crystal display device.
[0014]
When the color layer of the color filter and the overcoat layer made of the transparent resin are laminated, the dielectric loss tangent tan δ of the two layers shows a value of about 0.01 to 0.05 from 20 Hz to 1 MHz. More specifically, the behavior is about 0.01 in the range of 20 Hz to 1 kHz, but gradually increases from 1 kHz to 1 MHz, and reaches about 0.05 at 1 MHz.
The driving frequency of the liquid crystal is generally about 60 Hz, and it is considered that the behavior of the high frequency part does not have a great influence. However, the waveform of the driving signal of the liquid crystal is actually a rectangular wave, and inevitably contains a high-frequency component, so that the behavior of the dielectric loss tangent tan δ of the high-frequency portion has a great effect.
[0015]
For example, when a color layer and an overcoat layer of a color filter having a large dielectric loss tangent tan δ in a high-frequency portion are present, even when a liquid crystal driving signal is input as a rectangular wave, the liquid crystal rises and rises when actually driving the liquid crystal. The downhill shape is lost, and the signal is no longer a rectangular signal. This is fatal in recent liquid crystal display devices that aim to improve the response speed, and the voltage required to drive the liquid crystal is not sufficiently applied to the liquid crystal layer. Cause.
Therefore, the ideal dielectric loss tangent characteristics of the color layer and the overcoat layer of the color filter used in the horizontal electric field type color liquid crystal display device are as follows: “The dielectric loss tangent value is smaller and flatter over the entire range from low frequency to high frequency. It is desirable to have characteristics. "
[0016]
On the other hand, the relative permittivity is an index of energy stored in the dielectric. In a horizontal electric field type color liquid crystal display device, a color layer and an overcoat layer of a color filter, which is a dielectric, are inherent in a liquid crystal driving electric field. When a dielectric is placed in an electric field, energy is stored in the dielectric according to the relative dielectric constant, and as a result, the liquid crystal driving electric field is weakened.
For this reason, in the horizontal electric field type color liquid crystal display device, a phenomenon that the liquid crystal driving electric field does not have the intended strength may occur depending on the relative permittivity of the color layer and the overcoat layer of the color filter. Therefore, the relative permittivity of the color layer and the overcoat layer of the color filter is also one of the important characteristics that determine the display characteristics of the in-plane switching mode color liquid crystal display device.
[0017]
Therefore, the ideal relative dielectric constant characteristics of the color layer and the overcoat layer of the color filter used in the in-plane switching type color liquid crystal display device are that the relative dielectric constant value is smaller in the entire range from low frequency to high frequency. Is considered desirable.
[0018]
Examination of the pixels of the color filter by focusing on these characteristics reveals that, as shown in FIG. 2, the green (green) pixel specifically has a large dielectric loss tangent tan δ of about 0.1, which is about 0.1. Was. Actually, in the horizontal electric field type color liquid crystal display device, among the three color pixels of Red (Red), Green (Green), and Blue (Blue), the threshold deviation of the Green (Green) pixel, poor alignment, and the like are likely to occur. Is a major factor in reducing
[0019]
The present inventor has conducted various studies on the unique dielectric characteristics of Green (green) pixels in order to improve the display quality by eliminating the problem of threshold deviation and poor alignment of the Green (green) pixels.
As a result, in a color filter for a color liquid crystal display device having an overcoat layer made of a transparent resin, the dielectric loss tangent tan δ of the two layers obtained by laminating the overcoat layer on the color layer of the Green (green) pixel is 0 at a frequency of 20 Hz to 1 MHz. It has been found that the content is preferably set to 0.05 or less.
[0020]
In order to realize the above characteristics, it is most effective to suppress the amount of free halogen or free low-molecular compound containing halogen that migrates from the color layer of the green (green) pixel to the overcoat layer made of the transparent resin. .
As an effective means specifically mentioned as the means, for the color layer, the concentration of the copper phthalocyanine halide used mainly as a green pigment is set to a certain level or less, or the purification degree of the copper phthalocyanine halide is adjusted. And so on.
[0021]
In addition, as a result of various studies, in a color filter for a color liquid crystal display device having an overcoat layer made of a transparent resin, the relative permittivity of two layers obtained by laminating the overcoat layer on the color layer of the Green pixel is set to a frequency of 20 Hz to 1 MHz. It has been found that the content is preferably set to 5.0 or less in the range.
[0022]
In order to realize the above characteristics, it is most effective to suppress the amount of free halogens or free low-molecular compounds containing halogens that migrate from the color layer of the green (green) pixel to the overcoat layer made of the transparent resin. .
As an effective means specifically mentioned as the means, for the color layer, the concentration of the copper phthalocyanine halide used mainly as a green pigment is set to a certain level or less, or the purification degree of the copper phthalocyanine halide is adjusted. And so on.
[0023]
Hereinafter, a method for obtaining the color filter of the present invention will be described.
The color filter may be manufactured by any known method such as an inkjet method, a printing method, a photoresist method, and an etching method. However, in consideration of high definition, controllability of spectral characteristics and reproducibility, a coloring composition in which a pigment is dispersed in a suitable resin together with a photoinitiator and a polymerizable monomer in a transparent resin is formed on a transparent substrate. After coating and film formation, a photoresist method is preferred in which a color filter is produced by repeatedly performing a process of forming a one-color pattern by pattern exposure and development of the colored layer for each color.
[0024]
The transparent substrate used in the method of the present invention may be one generally used in a liquid crystal display device, and usually a glass substrate may be used. In the case of using a light-shielding pattern, a light-shielding resin pattern previously formed on the transparent substrate by a known method may be used.
[0025]
The pigment is dispersed in a suitable resin together with a photoinitiator and a polymerizable monomer in a transparent resin. There are various methods for dispersing, such as a mill base, a three-roll mill, and a jet mill, and there is no particular limitation.
[0026]
The above-mentioned photosensitive coloring composition is applied on a transparent substrate, and prebaked. The means for coating is usually spin coating, dip coating, die coating or the like, but is not limited thereto as long as it can be applied on a substrate of about 40 to 60 cm square with a uniform film thickness. The prebaking is preferably performed at 50 to 120 ° C. for about 10 to 20 minutes. The coating thickness is arbitrary, but is usually about 2 μm after prebaking in consideration of spectral transmittance and the like. The substrate coated with the photosensitive coloring composition is exposed through a pattern mask. An ordinary high-pressure mercury lamp may be used as the light source.
[0027]
Subsequently, development is performed. An alkaline aqueous solution is used as a developer. Examples of the alkaline aqueous solution include an aqueous sodium carbonate solution, an aqueous sodium hydrogen carbonate solution, a mixed aqueous solution of both, or a solution obtained by adding an appropriate surfactant or the like thereto. After development, it is washed with water and dried to obtain a pattern.
[0028]
By repeating the above series of steps by the required number of times by changing the photosensitive coloring composition and pattern, a colored pattern in which the required number of colors are combined can be obtained.
[0029]
Further, an overcoat layer made of a transparent resin is formed to obtain the color filter of the present invention. The transparent resin used for the overcoat layer is not particularly limited, but is preferably a mixture of an acrylic resin and an appropriate curing agent in terms of transparency and stability. From the viewpoint of the relative dielectric constant, the relative dielectric constant of the acrylic resin is about 3.2 to 3.5, which is suitable for the color filter of the present invention.
[0030]
【Example】
Hereinafter, the present invention will be described specifically with reference to examples.
<Example 1>
[Coloring composition]
The following coloring agents were used to color the coloring composition used for producing the color filter.
[0031]
Red pigment: C.I. I. Pigment Red 254 (“Ilgar For Red B-CF” manufactured by Ciba Specialty Chemicals), and C.I. I. Pigment Red 177 (“Chromophthal Red A2B” manufactured by Ciba Specialty Chemicals)
[0032]
Green pigment: C.I. I. Pigment Green 36 ("Lionol Green 6YK", manufactured by Toyo Ink Mfg. Co., Ltd.) was dispersed in 100-fold weight of pure water, stirred for 6 hours, and then filtered (with washing treatment). I. Pigment Yellow 150 ("Fanchon First Yellow Y-5688" manufactured by Bayer AG)
[0033]
Blue pigment: C.I. I. Pigment Blue 15 ("Lionol Blue ES" manufactured by Toyo Ink Mfg. Co., Ltd.) C.I. I. Pigment Violet 23 (“Paliogen Violet 5890” manufactured by BASF)
Red, green and blue coloring compositions were prepared using the respective pigments.
[0034]
・ Red coloring composition
After uniformly mixing and mixing a mixture having the following composition, the mixture was dispersed in a sand mill using a glass bead having a diameter of 1 mm for 5 hours, and then filtered through a 5 μm filter to prepare a red pigment dispersion.
Red pigment: C.I. I. Pigment Red 254 18 parts
Red pigment: C.I. I. Pigment Red 177 2 parts
Acrylic varnish (solid content 20%) 108 parts
Thereafter, the mixture having the following composition was stirred and mixed so as to be uniform, and then filtered through a 5 μm filter to obtain a red colored composition.
150 parts of the above dispersion
13 parts of trimethylolpropane triacrylate
(“NK ester ATMPT” manufactured by Shin-Nakamura Chemical Co., Ltd.)
3 parts of photoinitiator (“Irgacure 907” manufactured by Ciba Geigy)
1 part of sensitizer (“EAB-F” manufactured by Hodogaya Chemical Industry Co., Ltd.)
253 parts of cyclohexanone
[0035]
・ Green coloring composition
The compositions were prepared in the same manner as the red coloring composition so that the compositions were as follows.
Green pigment: C.I. I. Pigment Green 36 16 parts
Yellow pigment: C.I. I. Pigment Yellow 150 8 parts
Acrylic varnish (solid content 20%) 102 parts
Trimethylolpropane triacrylate 14 parts
(“NK ester ATMPT” manufactured by Shin-Nakamura Chemical Co., Ltd.)
4 parts of photoinitiator (“Irgacure 907” manufactured by Ciba Geigy)
2 parts of sensitizer (“EAB-F” manufactured by Hodogaya Chemical Industry Co., Ltd.)
257 parts of cyclohexanone
[0036]
・ Blue coloring composition
The compositions were prepared in the same manner as the red coloring composition so that the compositions were as follows.
Blue pigment: C.I. I. Pigment Blue 15 50 copies
Purple pigment: C.I. I. Pigment Violet 23 2 parts
Dispersant (Zeneca “Solutions 20000”) 6 parts
Acrylic varnish (solid content 20%) 200 parts
Trimethylolpropane triacrylate 19 parts
(“NK ester ATMPT” manufactured by Shin-Nakamura Chemical Co., Ltd.)
4 parts of photoinitiator (“Irgacure 907” manufactured by Ciba Geigy)
2 parts of sensitizer (“EAB-F” manufactured by Hodogaya Chemical Industry Co., Ltd.)
Cyclohexanone 214 parts
[0037]
[Transparent composition for overcoat]
The components were mixed so that the composition was as follows.
Acrylic varnish (solid content 20%) 200 parts
Trimethylolpropane triacrylate 20 parts
(“NK ester ATMPT” manufactured by Shin-Nakamura Chemical Co., Ltd.)
250 parts of cyclohexanone
[0038]
[Color filter]
A color filter was produced using the obtained coloring composition.
A red coloring composition was applied to a glass substrate by spin coating to a thickness of 2 μm. After drying, a stripe pattern exposure was performed by an exposure machine, and development was performed for 90 seconds with an alkali developing solution to obtain a colored layer of striped red pixels. The alkaline developer has the following composition.
1.5% by weight of sodium carbonate
Sodium bicarbonate 0.5% by weight
8.0% by weight of anionic surfactant
("Periolex NBL" manufactured by Kao Corporation)
90% by weight of water
[0039]
Next, the green coloring composition is similarly applied by spin coating so that the film thickness becomes 2 μm. After drying, the striped colored layer was exposed and developed at a position shifted from the colored layer of the red pixel by an exposure device to obtain a colored layer of a green pixel adjacent to the colored layer of the red pixel. .
[0040]
Further, in the same manner as in the case of red and green, a colored layer of a blue pixel adjacent to the colored layer of the red and green pixels was obtained with a thickness of 2 μm for the blue colored composition. Thus, a color filter having a striped colored layer of three colors of red, green and blue on the transparent substrate was obtained.
The transparent composition for overcoating was spin-coated to a thickness of 1 μm and cured at 200 ° C. to obtain a color filter having a transparent resin overcoat layer.
[0041]
<Example 2>
[Coloring composition]
The following coloring agents were used to color the coloring composition used for producing the color filter.
The red pigment and the blue pigment are the same as in Example 1.
Green pigment: C.I. I. Pigment Green 36 (“Lionol Green 6YK” manufactured by Toyo Ink Mfg. Co., Ltd.) without cleaning treatment, and C.I. I. Pigment Yellow 150 ("Fanchon First Yellow Y-5688" manufactured by Bayer AG)
Red, green and blue coloring compositions were prepared using the respective pigments. The red coloring composition and the blue coloring composition are the same as in Example 1.
[0042]
・ Green coloring composition
The mixture having the following composition was uniformly stirred and mixed, then dispersed in a sand mill using a glass bead having a diameter of 1 mm for 5 hours, and then filtered through a 5 μm filter to prepare a green pigment dispersion.
Green pigment: C.I. I. Pigment Green 36 11 parts
Yellow pigment: C.I. I. Pigment Yellow 150 8 parts
Acrylic varnish (solid content 20%) 102 parts
Thereafter, the mixture having the following composition was stirred and mixed so as to be uniform, and then filtered through a 5 μm filter to obtain a green colored composition.
121 parts of the above dispersion
Trimethylolpropane triacrylate 14 parts
(“NK ester ATMPT” manufactured by Shin-Nakamura Chemical Co., Ltd.)
4 parts of photoinitiator (“Irgacure 907” manufactured by Ciba Geigy)
2 parts of sensitizer (“EAB-F” manufactured by Hodogaya Chemical Industry Co., Ltd.)
257 parts of cyclohexanone
[0043]
[Transparent composition for overcoat]
It was manufactured with the same composition as in Example 1.
[0044]
A color filter was produced using the obtained coloring composition. The same red-colored composition and blue-colored composition as in Example 1 were used.
A red coloring composition was applied to a glass substrate by spin coating to a thickness of 2 μm. After drying, a stripe pattern exposure was performed by an exposure machine, and development was performed for 90 seconds with an alkali developing solution to obtain a colored layer of striped red pixels. The alkaline developer has the following composition.
1.5% by weight of sodium carbonate
Sodium bicarbonate 0.5% by weight
8.0% by weight of anionic surfactant
("Periolex NBL" manufactured by Kao Corporation)
90% by weight of water
[0045]
Next, the green coloring composition is similarly applied by spin coating so that the film thickness becomes 2 μm, dried, and then, by using an exposure machine, the striped coloring layer is shifted from the above-described red pixel coloring layer. The colored layer of the green pixel adjacent to the colored layer of the red pixel was obtained by exposing and developing.
[0046]
Further, in the same manner as in the case of red and green, a colored layer of a blue pixel adjacent to the colored layer of the red and green pixels was obtained with a thickness of 2 μm for the blue colored composition. As a result, a color filter having a striped colored layer of three colors of red, green and blue on the transparent substrate was obtained.
The transparent composition for overcoating was spin-coated to a thickness of 1 μm and cured at 200 ° C. to obtain a color filter having a transparent resin overcoat layer.
[0047]
<Comparative Example 1>
[Coloring composition]
The following coloring agents were used to color the coloring composition used for producing the color filter.
The red pigment and the blue pigment are the same as in Example 1.
Green pigment: C.I. I. Pigment Green 36 (“Lionol Green 6YK” manufactured by Toyo Ink Mfg. Co., Ltd.) without cleaning treatment, and C.I. I. Pigment Yellow 150 ("Fanchon First Yellow Y-5688" manufactured by Bayer AG)
Red, green and blue coloring compositions were prepared using the respective pigments. The red coloring composition and the blue coloring composition are the same as in Example 1.
[0048]
・ Green coloring composition
The mixture having the following composition was uniformly stirred and mixed, then dispersed in a sand mill using a glass bead having a diameter of 1 mm for 5 hours, and then filtered through a 5 μm filter to prepare a green pigment dispersion.
Green pigment: C.I. I. Pigment Green 36 16 parts
Yellow pigment: C.I. I. Pigment Yellow 150 8 parts
Acrylic varnish (solid content 20%) 102 parts
Thereafter, the mixture having the following composition was stirred and mixed so as to be uniform, and then filtered through a 5 μm filter to obtain a green colored composition.
126 parts of the above dispersion
Trimethylolpropane triacrylate 14 parts
(“NK ester ATMPT” manufactured by Shin-Nakamura Chemical Co., Ltd.)
4 parts of photoinitiator (“Irgacure 907” manufactured by Ciba Geigy)
2 parts of sensitizer (“EAB-F” manufactured by Hodogaya Chemical Industry Co., Ltd.)
257 parts of cyclohexanone
[0049]
[Transparent composition for overcoat]
It was manufactured with the same composition as in Example 1 and Example 2.
[0050]
[Color filter]
A color filter was produced using the obtained coloring composition. As the red coloring composition and the blue coloring composition, the same ones as in the examples were used.
A red coloring composition was applied to a glass substrate by spin coating to a thickness of 2 μm. After drying, the resultant was exposed to a stripe pattern using an exposure machine, and developed for 90 seconds with an alkaline developer to obtain a colored layer of striped red pixels. The alkaline developer has the following composition.
1.5% by weight of sodium carbonate
Sodium bicarbonate 0.5% by weight
8.0% by weight of anionic surfactant
("Periolex NBL" manufactured by Kao Corporation)
90% by weight of water
Next, the green coloring composition is similarly applied by spin coating so that the film thickness becomes 2 μm. After drying, the striped colored layer was exposed and developed at a position shifted from the colored layer of the red pixel by an exposure device to obtain a colored layer of a green pixel adjacent to the colored layer of the red pixel. .
[0051]
Further, in the same manner as for red and green, a blue colored layer having a thickness of 2 μm was obtained for the blue colored composition adjacent to the red and green pixel colored layers. As a result, a color filter having a striped colored layer of three colors of red, green and blue on the transparent substrate was obtained. The transparent composition for overcoating was spin-coated to a thickness of 1 μm and cured at 200 ° C. to obtain a color filter having a transparent resin overcoat layer.
[0052]
Table 1 shows a comparison of the concentration of the green pigment with respect to the solid content in the color layers of the green (green) pixels of the color filters of Example 1, Example 2, and Comparative Example 1.
In Example 1 and Comparative Example 1, the Green pigment, Pigment Green 36 occupies 24.8% of the solid content, whereas Example 2 accounts for 18.5%.
In addition, each of the washed green pigment and Pigment Green 36 used in Example 1 and the unwashed Green pigment and Pigment Green 36 used in Example 2 and Comparative Example 1 were mixed in pure water for 3 hours. Table 2 shows the values obtained by converting the eluting ion content per unit weight of the pigment when boiled for an hour. The Green pigment, Pigment Green 36, which had been subjected to the washing treatment in Example 1, had an improved degree of purification.
[0053]
[Table 1]

[0054]
[Table 2]

[0055]
FIG. 3 shows two dielectric loss tangents tan δ of the color filters of Example 1, Example 2, and Comparative Example 1 in which an overcoat layer made of a transparent resin is laminated on the color layer of a Green (green) pixel. In Example 1 and Example 2, the dielectric loss tangent tan δ was 0.05 or less in the range of 20 Hz to 1 MHz, whereas in Comparative Example 1, it became 0.05 or more from around 5000 kHz and reached 0.1 at 1 MHz.
[0056]
FIG. 4 shows the relative dielectric constants of two layers of the color filters of Example 1, Example 2, and Comparative Example 1 in which an overcoat layer is laminated on the color layer of a green (green) pixel. In FIG. 4, the numerical values of the first embodiment are not plotted because they are similar to the numerical values of the second embodiment.
In Example 1 and Example 2, the two layers of the color layer and the overcoat layer were 5.0 or less in the entire range of 20 Hz to 1 MHz, whereas in Comparative Example 1, it was 5.0 or more near 20 Hz. .
[0057]
Using the obtained color filters of Example 1, Example 2, and Comparative Example 1, liquid crystal display devices of an in-plane switching mode were formed, and a liquid crystal display using the color filters of Example 1 and Example 2 was obtained. In the device, the rising and falling shapes of the rectangular wave of the driving signal of the liquid crystal are smoothed, the occurrence of the threshold shift of the driving voltage is reduced, and the in-plane switching mode liquid crystal display device excellent in display performance is obtained. Was.
In the liquid crystal display device using the color filter of Comparative Example 1, no improvement in display performance was observed.
[0058]
【The invention's effect】
The present invention is directed to a liquid crystal of a horizontal electric field type, since a two-layer dielectric filter having a dielectric loss tangent tan δ of 0.05 or less in a frequency range of 20 Hz to 1 MHz is obtained by laminating an overcoat layer on a color layer of a green (green) pixel. When used in a display device, there is no disturbance in the alignment of liquid crystal due to unique electrical characteristics and no shift in switching threshold, that is, a color filter that does not adversely affect display performance.
[0059]
Further, the present invention is a color filter having a relative dielectric constant of 5.0 or less in a frequency range of 20 Hz to 1 MHz, which is a color filter of two layers in which an overcoat layer is laminated on a color layer of a green (green) pixel. When used in the liquid crystal display device of the above, there is no disturbance in the alignment of the liquid crystal due to the peculiar electrical characteristics or the shift of the switching threshold, that is, a color filter which does not adversely affect the display performance.
[Brief description of the drawings]
FIG. 1 is a graph showing values of dielectric loss tangent tan δ at 20 Hz to 1 MHz of two layers in which a color layer of a color filter and an overcoat layer made of a transparent resin are laminated.
FIG. 2 is a graph showing the values of the dielectric loss tangent tan δ at 20 Hz to 1 MHz of two layers in which an overcoat layer made of a transparent resin is laminated on each color layer of Red (Red), Green (Green), and Blue (Blue) of a color filter. It is.
FIG. 3 shows the values of the dielectric loss tangent tan δ at 20 Hz to 1 MHz of two layers in which an overcoat layer made of a transparent resin is laminated on a green pixel color layer of the color filters of Example 1, Example 2, and Comparative Example 1. It is a graph.
FIG. 4 shows values of relative dielectric constant at 20 Hz to 1 MHz of two layers in which an overcoat layer made of a transparent resin is laminated on a color layer of a Green pixel of the color filters of Example 1, Example 2, and Comparative Example 1. It is a graph.

Claims (6)

In a color filter for a color liquid crystal display device having an overcoat layer made of a transparent resin, a dielectric tangent tan δ of two layers in which an overcoat layer is laminated on a color layer of a Green (green) pixel is 0.05 at a frequency in a range of 20 Hz to 1 MHz. A color filter characterized by the following. The color filter according to claim 1, wherein the dielectric layer has a dielectric loss tangent tan δ of 0.05 or less in a frequency range of 20 Hz to 1 MHz. The color filter according to claim 1, wherein a dielectric loss tangent tan δ of the overcoat layer is 0.05 or less in a frequency range of 20 Hz to 1 MHz. In a color filter for a color liquid crystal display device having an overcoat layer made of a transparent resin, the relative permittivity of two layers obtained by laminating an overcoat layer on a color layer of a green (green) pixel is 5.0 in a frequency range of 20 Hz to 1 MHz. A color filter characterized by the following. The color filter according to claim 4, wherein the relative permittivity of the color layer of the green (green) pixel is 5.0 or less in a frequency range of 20 Hz to 1 MHz. The color filter according to claim 4, wherein the relative permittivity of the overcoat layer is 5.0 or less in a frequency range of 20 Hz to 1 MHz.

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