JPH06201911A - Color liquid crystal display - Google Patents

Abstract

(57) [Summary] [Purpose] To enable beautiful color display by using color filters with excellent light resistance, heat resistance, and chemical resistance. [Structure] A color filter comprises a colored layer mainly composed of a polyimide resin, an organic pigment dispersed in the polyimide resin, and a dispersion aid which improves the dispersibility of the organic pigment and is a derivative of an organic dye. It is characterized by Since all of them are excellent in light resistance, heat resistance, and chemical resistance, a color liquid crystal display device excellent in light transmittance and color purity can be obtained without fading or decomposition in the manufacturing process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color liquid crystal display device, and in particular, it is provided with a colored layer excellent in heat resistance and solvent resistance,
The present invention relates to a color liquid crystal display device capable of displaying beautiful colors.

[0002]

2. Description of the Related Art Panel type displays are required in many ways for CRTs (cathode ray tubes), which are said to have already achieved satisfactory performance and price for conventional home use, but have been further improved in performance. Efforts have been made to fill it, and it has grown to occupy about 20% of the market. Panel-type displays include LEDs (light-emitting diodes), liquid crystals, fluorescent displays, EL (electroluminescence), and plasma displays. The flat-panel thin structure and the coordinates are digitally fixed, and the CRT displays It is intended for non-penetrating applications.

Among the panel type displays, the liquid crystal panel is a TN type liquid crystal, which has a great advantage of low voltage and low power consumption, and covers the difficulty of seeing due to the strong viewing angle dependence, and is mainly used in calculators, watches, games and the like. ing. Even in the matrix display, the number of rows restricted by the effective voltage dependency, the viewing angle, the temperature characteristics, etc. is improved every year, and 128 of 1/64 time division drive
The row panel was put to practical use. The GH type liquid crystal can be easily selected in display color, has a wide viewing angle, has little dependence on cell spacing and temperature, and is being put to practical use by improving the dichroism and life of the dye.

In such a liquid crystal display device, a color filter system is a method of achieving full color and excellent color reproducibility. The color filter is provided inside or outside the liquid crystal cell, and the liquid crystal is used as an optical shutter to realize a full-color display panel.

When it is provided in a color filter liquid crystal cell, it is required to have excellent properties in terms of transparency, light resistance, heat resistance and chemical resistance. That is, in the liquid crystal cell manufacturing process, chemical resistance is required from the cleaning step, and heat resistance is required from the alignment film forming step, the transparent conductive film forming step, the liquid crystal encapsulating sealing step, and the like. However, an organic filter, which is currently used for color liquid crystal display and uses a dye-dyed polypeptide as a material for a filter layer, has a heat resistance of 20%.
The limit is about 0 ° C. and the chemical resistance is poor, and there are many problems as a color filter for a color liquid crystal display device.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been achieved by conducting various kinds of investigations in order to compensate for the weaknesses of the liquid crystal display device using the above dye-dyeing type organic filter, and has realized light resistance, heat resistance, The purpose is to enable beautiful color display by using a color filter having excellent chemical resistance.

[0007]

That is, the present invention provides a color composed of a transparent substrate having a transparent electrode, a transparent substrate having a transparent electrode and a color filter, and a liquid crystal sandwiched between these transparent substrates. In liquid crystal display devices,
The color filter has a polyimide resin, an organic pigment dispersed in the polyimide resin, and a dispersion assistant for improving the dispersibility of the organic pigment, which is a dispersion assistant consisting of a derivative of an organic dye. It is characterized in that it comprises a colored layer.

The liquid crystal display device according to the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a color liquid crystal display device. White light 1 emitted from the plateau is polarizing plate 2, transparent substrate 3
Through the transparent pixel electrode 4, the alignment film 5, the liquid crystal 6, the alignment film 7, and the transparent common electrode 8 to pass through the colored layer 9, and are separated into three primary colors. In response to an electric signal applied to the pixel electrode 4 and the common electrode 8, the liquid crystal 6 is aligned and operates as an optical shutter by the action of the polarizing plate 11, and the electric signal is converted into information of three primary color lights. The size of each color of the colored layer 9 is the same as that of the pixel electrode 4, and is on the order of several millimeters to several tens of microns to several hundreds of microns depending on various types of liquid crystal display devices. Will be needed. FIG. 2 shows a color filter applied to this liquid crystal display device. As shown in FIG. 2, each colored layer 9 is configured to be protected by protective layers 15, 16 and 17 layer by layer. In the case of a color liquid crystal display device, the colored layer 9 is a red layer 12, a green layer 13, and a blue layer 14.
It consists of three colors. Each colored layer 12, 13, 14 is composed of a polyimide resin, a pigment, and a dispersion aid. This colored layer 1
2, 13, and 14 have a role of color-separating white light,
It must also be transparent, lightfast, chemical resistant, patternable, and dispersible in pigments. Polyimide has the above-mentioned characteristics by itself, but it is difficult to disperse the pigment, and it is necessary to add a dispersion aid to prevent the pigment from aggregating and to disperse it uniformly. The dispersion aid must also have heat resistance. Derivatives of dyes are extremely effective as dispersion aids that meet this purpose. Also,
Since the polyimide does not have solvent resistance, the colored layers 12 and 13, when the positive resist is coated or when the positive resist is peeled off,
14. The polyimide resin is cracked and loses transparency. In addition, when patterning several colors after the colored layer 12 is patterned with one color, that is, when the second colored polyimide resin is coated, the first colored layer 12 is cracked by the solvent of the second colored polyimide to improve transparency. lose. When the alignment film is coated after patterning several colors, the colored layers 12, 13 and 14 are similarly cracked. Further, since polyimide is weak against an alkaline solution, the colored layers 12, 13 and 14 are attacked even when washed with an alkaline solution. The protective layers 15, 16 and 17 are required to improve the solvent resistance and alkali resistance. This protective layer 1
Nos. 5, 16 and 17 are required to have a composition that does not cause cracks in the polyimide resin during coating, and are required to have transparency, heat resistance, chemical resistance and light resistance. A transparent polyimide resin can be used as the protective layers 15, 16 and 17, but when it is coated as a polyimide resin solution, the polyimide resin of the colored layers 12, 13 and 14 is attacked and cracks occur. When coating the protective layers 15, 16 and 17 with a resin, a solvent that does not attack the polyimide resin is required, and aromatic hydrocarbons, hexane-based solvents such as xylene and cyclohexanone are effective. An acrylic resin is effective as a resin that is soluble in the solvent, has transparency, and has heat resistance, chemical resistance, and light resistance. Further, it is advantageous that patterning is possible at the time of stacking, and far-ultraviolet rays and acrylic resins sensitive to ultraviolet rays are effective. The resin considered to satisfy the above requirements is, for example, a copolymer of cinnamic acid ester of glycidyl methacrylate and glycidyl methacrylate, a copolymer of glycidyl methacrylate and ethyl acrylate, and a resin for improving heat resistance. Examples thereof include a copolymer of glycidyl methacrylate and styrene, a copolymer of glycidyl methacrylate and methacrylic acid chloride, and a copolymer of glycidyl methacrylate and α-acid acrylate. These acrylic resins have heat resistance up to at least 300 ° C., and have chemical resistance to alkalis, acids, and solvents, and moreover, they are heat-cured at a low temperature of about 200 to 300 ° C., and therefore they are used during the heat-curing process for filters. The organic pigment in the layer does not fade. Furthermore, wavelength 400-700n
It is characterized by excellent transparency and little light absorption in the visible region of m. Further, it is convenient for these acrylic resins to have a photosensitive group that imparts a property of being polymerized and cured by being exposed to ultraviolet rays, because it can be partially cured by a photographic method and patterned by development.

It is possible to provide the colored layers of several colors on the transparent substrate for the first time with the acrylic resin interposed as a protective layer.

The polyimide resin used for the colored layer will be described in more detail. The polyimide resin used in the colored layer according to the present invention is generally obtained by a condensation reaction of a polyimide precursor or an addition reaction. The polyimide precursors currently commercialized are mainly of condensation reaction type. For example, tetracarboxylic acid dianhydride, biphenyltetracarboxylic acid dianhydride and aromatic diamine are polymerized in a solvent to prepare a polyamine acidic solution, that is, polyimide. Produce a precursor. The patterning of the polyimide resin is AZ
-1350 (Shipley Company, USA; trade name), OFPR
(TOKYO OHKA KOGYO CO., LTD .; trade name) is used, and it is performed by etching the photoresist and the polyimide resin together with a photoresist developing solution. In this method, a polyimide precursor coated on a substrate is heated at 100 to 150 ° C. to be semi-cured, and a photoresist is coated on the polyimide precursor.
The photoresist is exposed to light and developed with an alkaline solution. After development, the exposed polyimide precursor is semi-cured and therefore soluble in an alkaline solution, so that the photoresist serves as a mask and is etched and patterned by the alkaline solution. The alkaline solution is photoresist AZ13.
In 50, a strong alkaline solution such as tetramethylammonium hydroxide is used, and the photoresist OFP is used.
In R, an alkaline solution such as sodium carbonate or sodium hydroxide is used. As another etching method,
There is a method in which a polyimide precursor is heated to a state where it is almost imidized and then etched with a mixed solution of hydrazine hydrate and ethylenediamine using a negative coat resist. There is also a method of using oxygen plasma, oxygen sputtering, or the like, laminating a metal film of Mo, Cr, or the like by vapor deposition, and dry-etching the polyimide film using the metal film as a mask.

The composition of the polyimide precursor according to the present invention will be described in more detail. The polyimide precursor is composed of a polyimide precursor, a pigment, and a dispersion aid in order to provide a colored layer having a color division. The role of the polyimide resin is to fix the pigment of each color on the substrate, to enable patterning of an arbitrary shape as necessary, and to form a transparent conductive film on the colored layer. The pigment of each color has a role of color-separating white light and must have excellent transparency, light resistance, and heat resistance. The primary particle diameter of the pigment is 0.3 micron or less, which is sufficiently small for the wavelength of visible light. An organic pigment is applied to the filter layer as a pigment having excellent transparency. The dispersion aid is added to prevent aggregation of the pigment and to uniformly disperse the pigment in the polyimide resin.
The dispersion aid also needs heat resistance. It has been found that dye derivatives are extremely effective as dispersion aids that meet this purpose.

The weight ratio of the pigment to the polyimide resin 1 is usually preferably in the range of 3 to 0.05. When the ratio of the pigment is reduced, the characteristics as a filter are improved, but in order to obtain a predetermined optical density, it is necessary to increase the film thickness, which makes fine processing difficult. If the ratio of the pigments is increased, the dispersibility of the pigments and the coating properties are significantly deteriorated. Therefore, the weight ratio of the pigment to the polyimide resin is preferably 0.5 to 3. The weight ratio of the dispersion aid to the pigment is 0.01.
However, the value is not necessarily limited to this value.

Next, as the pigment, materials having high transparency and excellent heat resistance, light resistance and chemical resistance are shown below. All materials are indicated by color index (CI) number.

C. I. Pigment Yellow; 20, 2
4, 86, 93, 109, 110, 117, 125, 1
37, 138, 148, 153, 154, 166, 16
8. C. I. Pigment Orange; 36, 43, 51, 5
5, 59, 61. C. I. Pigment Red; 9, 97, 122, 12
3, 149, 168, 177, 180, 192, 21
5, 216, 220, 223, 224, 226, 22
7, 228, 240. C. I. Pigment Violet; 19, 23, 29,
30, 37, 40, 50. C. I. Pigment Blue; 15, 15: 6, 22, 6
0, 64. C. I. Pigment Green; 7,36. C. I. Pigment Brown; 23, 25, 26. C. I. Pigment Black; 7.

Next, as a dispersion aid usable in the present invention,
Derivatives of organic dyes are effective. The organic pigment derivative is an organic pigment or dye derivative, and examples thereof include azo, phthalocyanine, quinacridone, anthraquinone, perinone, thioindigo, dioxazine, isoindolinone, quinophthalone, and triphenylmethane. It is a compound having a substituent in an organic dye compound of a system or a metal complex salt system. The substituent is a substituent represented by the following general formula such as a hydroxyl group, a carboxyl group, a sulfonic acid group, a carbonamide group, a sulfonamide group.

[0016]

[Chemical 1]

(X: oxygen or sulfur atom, A: aryl group)

[0018]

[Chemical 2]

[0019]

[Chemical 3]

(X: alkylene group, R ₁ , R ₂ ; hydrogen atom, alkyl group or heterocycle containing at least a nitrogen atom for R ₁ and R ₂ )

[0021]

[Chemical 4]

(R ₁ ; hydrogen atom, alkyl group or aryl group, R ₂ ; alkyl group or aryl group, or R ₁
And a heterocycle containing at least a nitrogen atom for R ₂ )

[0023]

[Chemical 5]

[0024]

[Chemical 6]

(R ₁ ; hydrogen atom or alkyl group, A;
Alkylene group, R ₂ ; alkyl group, alkoxyalkyl group or cycloalkyl group, R ₃ ; hydrogen atom, alkyl group or cycloalkyl group, or heterocycle containing at least a nitrogen atom for R ₂ and R ₃ )

The organic pigment and the matrix organic dye of the derivative are usually the same in terms of hue, but they are not necessarily the same.

As a structure of the color filter, as shown in FIG. 3, a black light shielding layer 19 may be interposed between the colored layers of the respective colors. In this case, the light-shielding layer 19 may be formed of a coloring composition containing a black pigment such as carbon black by the above-mentioned etching means or printing means. Since the light-shielding layer 19 is required to have heat resistance similarly to the colored layer, it is preferable to use a heat-resistant resin layer such as polyimide in which a black pigment is dispersed. In addition, it is also possible to form a black substance such as a metal or a metal compound by means such as vapor deposition.

When a voltage is applied to both the common electrode 8 and the pixel electrode 4 in FIG. 1, an electric field is applied between the electrodes to align the liquid crystal 6 and act as a polarizing plate to function as a white light shutter.

If a thin film transistor is used, it functions as a switching element corresponding to the red, green, and blue colored layers 9 of each pixel, and controls the transmission amount of each light. Just like a color CRT, an arbitrary color is produced by mixing the three primary colors. The common electrode 8 on the colored layer can be directly provided on the substrate, and the colored layer can be laminated on the electrode. In that case, the protective layer also needs to be patterned.

[0030]

According to the present invention, the color filter comprises a polyimide resin, an organic pigment dispersed in the polyimide resin, and a dispersion aid for improving the dispersibility of the organic pigment, which is a derivative of an organic dye. Since it is composed of a colored layer containing a dispersion aid as a main component, the heat resistance required in the substrate washing process, the alignment film forming process, the transparent conductive film forming process, the liquid crystal encapsulating sealing process, etc.
Satisfies chemical resistance and does not cause fading or decomposition reaction. Therefore, it is possible to obtain a color liquid crystal display device having excellent light transmittance and color purity.

[0031]

EXAMPLES Color filters applied to the liquid crystal display device of the present invention will be described below based on examples.

(Example 1) To 90.1 g of a polyimide precursor (Semi-Coffein SP-910 manufactured by Toray Industries, Inc.), 90. g and 0.9 g were added and sufficiently kneaded with a three-roll mill to prepare red, green and blue colored varnishes. The pigments and dispersion aids are shown below.

(For red varnish) (a) Pigment. Riotgen Red GD (manufactured by Toyo Ink Mfg. Co., Ltd .; C.I.
I. Pigment Red 168) 6.75 g and Lionol Orange R (manufactured by Toyo Ink Mfg. Co., Ltd .; CI Pigment Orange 36) 2.25 g.

(B) A compound having the following structural formula.

[0035]

[Chemical 7]

(For green varnish) (a) Pigment. Lionol Green 2YS (manufactured by Toyo Ink Mfg. Co., Ltd.)
C. I. Pigment Green 36) 6.75 g and Lionol Yellow 3G (manufactured by Toyo Ink Mfg. Co., Ltd .; CI Pigment Yellow 154) 2.25 g.

(B) The following copper phthalocyanine derivative.

[0038]

[Chemical 8]

(For blue varnish) (a) Pigment. Lionol Blue ES (manufactured by Toyo Ink Mfg. Co., Ltd.); C.I.
I. Pigment Blue 15: 6) 7.2 g and Rionogen Violet RL (manufactured by Toyo Ink Mfg. Co., Ltd .; C.I.
I. Pigment Violet 23) A mixture with 1.8 g.

(B) The following copper phthalocyanine derivative.

[0041]

[Chemical 9]

Next, 2 g of N-methyl-2pyrrolidone (hereinafter abbreviated as "NMP") was added to 10 g of the red varnish, and the mixture was sufficiently stirred to spinner 1500 on a glass substrate.
spin coating for 60 seconds at 60 rpm,
It was prebaked for 15 minutes to form a red film. Next, a positive photoresist (manufactured by Tokyo Ohka Co., Ltd.) was formed on the red film.
OFPRII) 25 cp was spinner coated at a speed of 2000 rpm, pre-baked at 60 ° C. for 60 minutes, pattern-exposed with an ultra-high pressure mercury lamp, developed with an alkali developing solution, and the red film was etched with the developing solution to pattern the red film. Then, the unexposed portion of the OFPRII photoresist was stripped with a mixed solution of xylene and N-butyl acetate in a ratio of 1: 2, and baked at 250 ° C. for 30 minutes to form a red colored layer. After that, Fuji Yakuhin Co., Ltd. for acrylic resin coating liquid
Manufactured; FVR-G-10 was spinner coated at a speed of 1000 rpm, dried at 60 ° C. for 20 minutes, and then at 250 ° C., 30
It was baked for a minute to form an intermediate protective film.

Next, 4 g of NMP was added to 10 g of the green varnish.
Add, mix, stir, spin-coat on the FVR-G-10 intermediate protective film at a speed of 2000 rpm for 60 seconds, and then treat in the same manner as for the red varnish, pattern so that it does not overlap red, and color green. Layers were formed. Next, 2.5 g of NMP was added to 10 g of the blue varnish, and after stirring and mixing,
FVR-G-10 is applied on the green colored layer and applied on the fired FVR-G-10 intermediate protective film, treated in the same manner as the red varnish to form a blue colored layer, and then FVR-G-10 is applied similarly to the red layer. Then, it was cured at 250 ° C. for 30 minutes. After forming the colored layer and the protective layer of these three colors, the
An O film was formed and baked at 300 ° C. for 1 hour to manufacture a color filter.

Example 2 A pigment precursor (PIQ) manufactured by Hitachi Chemical Co., Ltd. (PIQ) (120 g) was added with a pigment and a dispersion auxiliary in an amount of 90. g and 0.9 g were added and sufficiently kneaded with a three-roll mill to prepare red, green and blue colored varnishes. The same pigment and dispersion aid as in Example 1 were used. An ITO film was formed on a glass substrate by sputtering and baked at 300 ° C. for 1 hour. After that, a solution prepared by adding 3 g of NMP to 10 g of the blue varnish was spin-coated at a speed of 1800 rpm for 60 seconds.
C., dried for 15 minutes, and heated at 120.degree. C. for 30 minutes. ITO is sputtered on the blue film to a thickness of 60 nm and the temperature is 12 ° C.
On the ITO film for 20 minutes, and then OFPRII25
cp spin coated at 2000 rpm, 60 ° C
After prebaking for 60 minutes, pattern exposure was performed and alkali development was performed. The ITO film exposed by the development is OFPRII.
Was used as a mask to etch with a 1.5% hydrochloric acid solution, and the lowermost blue film was further etched with the above-mentioned alkaline developer. After that, OFPRII was exposed to the front and peeled off with an alkali developing solution, and the entire exposed ITO film was etched with a 1.5% hydrochloric acid solution to leave only a patterned blue film. Then, the blue colored layer is baked at 250 ° C. for 30 minutes, and an acrylic resin coating liquid FVR-G-10 manufactured by Fuji Yakuhin Co., Ltd. is spin-coated at a speed of 1000 rpm on the blue colored layer, and the temperature is 70 ° C. for 30 minutes. Dried. After that, pattern exposure was performed with an ultra-high pressure mercury lamp, solvent development was performed, and terminals were exposed. The FVR-G-10 film was dried at 60 ° C for 20 minutes and then heated at 250 ° C for 30 minutes to be cured. Next, 2 g of NMP was added to 10 g of the green varnish, mixed and stirred, and spin-coated on the FVR film at a speed of 1500 rpm for 60 seconds. Thereafter, the same treatment as for the blue varnish was performed to pattern the green colored layer and the FVR layer. Red varnish 10g
4 g of NMP was added, mixed and stirred, spin-coated on the FVR-G-10 layer on the green colored layer at a speed of 1000 rpm for 60 seconds, and treated again in the same manner as the blue or green colored layer described above. Similarly, the FVR-G-10 film was patterned to expose the lowermost ITO film as a terminal to manufacture a color filter.

[0045]

As described above, according to the present invention, a color liquid crystal display device having an excellent light transmittance and color purity can be obtained. Therefore, it is possible to obtain a high quality color liquid crystal display device capable of displaying beautiful colors. Produce an effect.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a color liquid crystal display device according to an embodiment.

FIG. 2 is a sectional view of a color filter of the color liquid crystal display device.

FIG. 3 is a cross-sectional view showing another example of the color filter of the color liquid crystal display device.

[Explanation of symbols]

 1 White light. 2 Polarizing plate. 3 Transparent substrate. 4 pixel electrodes. 5 Alignment film. 6 liquid crystal. 7 Alignment film. 8 Common electrode. 9 Colored layer. 10 Transparent substrate. 11 Polarizing plates 12, 13, 14 Coloring layers 15, 16, 17 Protective layer 18 Substrate 19 Light-shielding layer

Claims (1)

[Claims] 1. A color liquid crystal display device comprising a transparent substrate having a transparent electrode, a transparent substrate having a transparent electrode and a color filter, and a liquid crystal sandwiched between these transparent substrates, wherein the color filter comprises: A polyimide resin, an organic pigment dispersed in the polyimide resin, and a coloring layer containing a dispersion aid for improving the dispersibility of the organic pigment as a dispersion aid which is a derivative of an organic dye as a main component. A color liquid crystal display device characterized by the above.