JPH0812290B2 - Color filter and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention can provide a suitable color filter by providing it in a liquid crystal cell of a color liquid crystal display device.
More specifically, color filters for color separation suitable for TN (twisted nematic) liquid crystal display, GH (guest host) liquid crystal display, STN (super twisted nematic) liquid crystal display, and FLC (strong induction liquid crystal) display device. And a manufacturing method thereof.

<Purpose of the invention> Acrylic resins have excellent heat resistance, transparency, and chemical resistance, while pigments are superior in heat resistance and light resistance to dyes. We were able to create a color filter for liquid crystal display.
It is an object of the present invention to provide a color filter excellent in this characteristic.

<Prior Art> Conventionally, a color filter has been produced by purifying a dyeable organic natural substance (gelatin, casein, etc.) to obtain a low molecular weight (10,000 to 5).
It is disassembled into 10,000). Since this organic substance is soluble in water, the coating of the aqueous solution, patterning dyeing, and baking were repeated for each coloring to produce a color filter. However, there is a drawback that the chromosome is a natural product, so that it is weak in heat resistance, and because it uses a dye, it is also weak in light resistance. On the other hand, various studies have been conducted on the use of pigments for improving heat resistance and light resistance, but there is a problem with the dispersibility of the pigments, and it is difficult to produce a practical color filter having good uniformity and high transparency. . Further, vapor deposition of a transparent electrode for operating the liquid crystal on the color filter, coating of a polyimide resin for orienting the liquid crystal, and baking are required, and there is a problem in heat resistance.

On the other hand, the light resistance may be directly exposed to sunlight when used for outdoor and vehicle use, and high light resistance has been desired.

<Problems to be Solved by the Invention> As described in the prior art, dye-type color filters using gelatin and casein have some problems in heat resistance and light resistance. Further, it has been studied to improve light resistance by using a pigment, but there is a problem in dispersibility of the pigment,
It was difficult to improve transparency and uniformity. However, by using a pigment derivative as a pigment dispersant, it has become possible to produce a color filter having good uniformity and transparency.

<Means for Solving the Problems> Next, the color filter of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a liquid crystal display device using a color filter. White light emitted from a fluorescent lamp or the like as the light source (1) proceeds to the liquid crystal (6) through the polarizing plate (2) and the transparent substrate (3), the image electrode (4) and the alignment film (5), and further. It passes through the alignment film (8) and the transparent electrode (9) and is separated into three primary colors by the color filter (10). Further, it passes through the transparent substrate (11), passes through the polarizing plate (12), and is visually recognized as a color. In such a device, the liquid crystal (6) is sealed in contact with the alignment films (5) and (8) and the sealing material (7), and is applied between the pixel electrode (4) and the transparent electrode (11). The orientation is changed according to the electric signal. At this time, the polarizing plates (2) and (12) act as an optical shutter, and the light passing through the color filter is converted into information. The size of each color of the color filter (10) is the same as that of the pixel electrode (4), and is several millimeters square for a large display, and tens of microns to hundreds of microns square for a handheld display. The filter (10) must be composed of a material that can be microfabricated.

Next, the structure of the color filter of the present invention will be described below. As the transparent substrate (11) as shown in FIG. 1, a glass substrate transparent resin plate, a transparent resin film or the like can be applied.

The color filter (10) is usually located on the transparent substrate (11), and a transparent electrode (9) is generally provided on the color filter (10). However, in some cases, a transparent electrode may be provided on the transparent substrate (11), and the color filter may be located thereon. As shown in FIG. 1, the color filter (10) is composed of, for example, a red filter layer (R), a green filter layer (G) and a blue filter layer (B). In some cases, a black or opaque light-shielding layer or a non-colored layer is (R),
It may be provided between (G) and (B).
The red filter layer (R) is acrylic resin, red pigment,
It is composed mainly of a dispersant. Similarly, the green filter layer (G) and the blue filter layer (B) are also made of acrylic resin, pigment and dispersant. The role of the acrylic resin is to fix each color pigment on the transparent substrate (11) and to make a pattern in any shape as needed, and further to mount the transparent electrode (9) on the color filter (10). It becomes the base material when it is formed. Since each color pigment plays a role of decomposing white light, it must have excellent transparency, light resistance, and heat resistance. The primary particle diameter of the pigment is 0.3 μm or less, preferably 0.1 μm or less, which is sufficiently small for the wavelength of visible light. Furthermore, organic pigments are desirable as highly transparent pigments. As a dispersant, prevent the aggregation of pigments,
It is added to uniformly disperse the pigment in the acrylic resin. Therefore, the dispersant also has heat resistance and must not interfere with the properties of the color filter (10). Organic dispersants of pigments or dyes have been found to be extremely effective as dispersants for this purpose. The dispersant is not limited to the derivative of the pigment, of course, and a cationic activator, an anionic activator, a nonionic activator and the like can be applied.

The weight ratio of the pigment to the acrylic resin is usually preferably in the range of 0.25 to 3. 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 microfabrication difficult. When the ratio of the pigment is increased, the dispersibility of the pigment and the coating property are significantly deteriorated. The weight ratio of the dispersant to the pigment is preferably 0.01 to 0.2, but it is not always limited to this value. The thickness of the color filter having the above composition was 0.75 μm to 3.0 μm. The typical spectral characteristics of the color filter thus produced are shown in FIG.

The acrylic monomer for constituting the acrylic resin that can be used in the present invention has a general formula, There are acrylate and methacrylate (representing R ₁ = H or CH ₃ , R ₂ = alkyl, branched alkyl, or phenyl or cyclohexyl group), and specific examples of the monomer mainly usable in the present invention are: (However, R = H or CH ₃ , n, and m = 0 to 6 are integers). However, in addition to the above compounds, for example, Etc. can be used in place of (b) and (c). It is possible to use a resin synthesized from several kinds of monomers selected as necessary from these.

A suitable composition ratio of the monomers (a) (b) (c) is
(A) 5 to 30 parts by weight, (b) 20 to 40 parts by weight, (c) 40 to
60 parts by weight can be raised.

Examples of the solvent used when synthesizing the resin include methyl cellosolve, ethyl cellosolve, cyclohexanone and xylene. Further, a mixture of these solvents may be used, but ethyl cellosolve is particularly preferable from the viewpoint of solubility and coating property.

Examples of the dye that can be used in the present invention include dyes and pigments, and pigments are preferable in terms of heat resistance and light resistance.

As pigments, inorganic pigments such as barium sulfate, zinc white, lead sulfate titanium oxide, yellow lead, red iron oxide, ultramarine blue, navy blue, chromium oxide, carbon black, benzine yellow G, benzine yellow GR, resor fast orange 3GL, vulcan First Orange GC, Pigment Scarlet 3B, Thiokundigo Maroon, Phthalocyanine Blue, Phthalocyanine Green, Indanthrene Blue, Green Gold, Macalite Galeen Lake, etc., but are specifically shown by color index (CI) number.

CI yellow pigment 20,24,86,93,109,110,117,125,137,138,147,148,153,15
4,166,168 CI orange pigment 36,43,51,55,59,61, CI red pigment 9,97,122,123,149,168,177,180,192,215,216, or 217,2
20,223,224,226,227,228,240 CI violet pigment 19,23,29,30,37,40,50 CI blue pigment 15,15: 6,22,60,64 CI green pigment 7,36 CI brown pigment 23,25,26 CI black pigment 7 pcs The dispersant according to the invention is a derivative of an organic dye, and as the organic dye which is a base, an azo type, a phthalocyanine type,
Examples include quinacridone type, anthraquinone type, perylene type, perinone type, thioindico type, dioxazine type, isoindolinone type, quinophthalone type, triphenylmethane type and metal complex salt type. A derivative having a substituent in these organic dyes and effective in dispersing the dye is used. The substituent is a hydroxyl group, a carboxyl group, a sulfonic acid group, a carbonamide group, a sulfonamide group, or any substituent represented by the following general formula. A derivative having at least one kind of substituent selected from these substituents is used.

General formula —CH ₂ —X—A (X: oxygen or sulfur atom, A: aryl group) (X: alkylene group, R ₁ , R ₂ : hydrogen atom or alkyl group, or R ₁ and R ₂ and a heterocycle containing at least a nitrogen atom) (R _{1 is a} hydrogen atom, an alkyl group or an aryl group, R _{2 is} an alkyl group or an aryl group, or R and R are heterocycles containing at least a nitrogen atom) (R ₁ : hydrogen atom or alkyl group, A: alkylene group, R ₂ :
Alkyl group, alkoxyalkyl group or cycloalkyl group, R ₃ : hydrogen atom cycloalkyl group, or R ₂ and R ₃
A heterocycle containing at least a nitrogen atom in and) The dye and the base organic dye of the dispersant are usually the same in combination in terms of hue, but they do not necessarily match.

In the composition of the present invention, the composition ratio is not particularly limited, but usually 10 to 50% by weight of the acrylic resin relative to the composition.
The proportion of the pigment varies depending on the type of the acrylic resin and the type of the pigment, but is about 1 to 30% by weight with respect to the acrylic resin, and the dispersant varies depending on the type of the pigment and the like. It is about 0.1 to 30% by weight. Furthermore, the coloring composition of the present invention can also be used as a color concentrate having a high dye content. It should be noted that additives can be blended if necessary.

In order to prepare a coloring composition or the like based on the present invention, an acrylic resin, a solvent, a dye and a dispersant are dispersed and mixed by a roll mill, a ball mill, a sand mill, an attritor, and other dispersing and mixing devices. It can also be prepared by previously dispersing an acrylic resin, a dye and a dispersant with a roll mill or the like, and then diluting with a solvent or an acrylic resin and a varnish of the solvent. It is also possible to mix the pigment and the dispersant, and then mix and disperse with a varnish or the like. Note that the order of mixing and dispersing is not limited to this and can be appropriately performed.

When the colored composition of the present invention is used as a polymerization method, various monomers and polymerization initiators to be added can be used. As the monomer, there are bifunctional and trifunctional monomers, and as the bifunctional monomer, 1.6-hexanediol is used. Diacrylate, ethylene glycol diacrylate,
There are neopentyl glycol diacrylate, triethylene glycol diacrylate, bis (acryloxyethoxy) bisphenol A, 3-methylpentanediol diacrylate, and the like, and trimethylolpropane triacrylate, pentaerythritol triacrylate, tris (2 -Hydroxyethyl)
There are isocyanates and the like, and these monomers are commercially available products such as Showa High Polymer Co., Ltd., Toagosei Co., Ltd., and Celanese Chemical Co., Ltd. Further, as the photopolymerization initiator,
There are acetophenone, benzophenone benzyl dimethyl ketal, benzoyl peroxide, 2-chlorothioxanthone and the like, and commercially available products from Daito Chemical Industry Co., Ltd., Shin Nisso Kako Co., Ltd., Ciba Geigy, Osaka Organic Co., Ltd., etc. In addition, various commercially available primers may be added to the composition in order to improve the adhesion of the substrate to the composition, or the composition may be coated after the substrate is previously coated and dried.

The method for producing a color filter according to the present invention includes (1) a step of adding a pigment and a dispersant to the acrylic resin, and sufficiently kneading the mixture with a stirrer such as a three-roll to produce a coloring composition of each color,
(2) a step of adding a polymerization initiator and an acrylic monomer to the composition, (3) applying the coloring composition to a transparent substrate and then patterning it, or applying it to a pattern line to heat-condense,
A colored filter layer composed of an acrylic resin, a pigment and a dispersant is formed, and the above steps are further repeated if necessary to
The process comprises the steps of forming a color filter having a combination of hues of more than color. Here, the acrylic resin is a dispersion medium for the pigment, and the dispersant is an auxiliary agent for uniformly dispersing the pigment in the acrylic resin. The pigment and dispersant are added to an acrylic resin and sufficiently kneaded with a three-roll mill or the like to produce a colored varnish of each color. Next, the colored varnish, for example, a red varnish, is applied onto the transparent substrate (11) with a spinner, a roll coater or the like. Next, the solvent is removed at a temperature of 230 ° C. or lower to form a dry film of the colored varnish, that is, a colored filter layer (13).

Next, using a super high pressure mercury lamp or the like, mask exposure and development are performed to form a relief pattern of the colored filter layer.
This operation is repeated two more times, and R, G, B (red,
FIG. 3 shows the formation of green and blue). FIG. 4 shows that a gap is provided between each colored pattern, a black coloring composition is used for coating between the colored patterns, back exposure, development and baking are performed, and a black stripe or a black stripe is formed between the colored patterns (15). It is provided with a grid pattern light-shielding film (16).

Examples of the present invention will be described below. All mixing ratios are weight ratios.

<Example> Acrylic resin (methacrylic acid 20 parts, butyl acrylate 30 parts, butyl methacrylate 50 parts with ethyl cellosolve
It was dissolved in 300 parts, 0.75 parts of azobisisobutyronitrile was added under a nitrogen atmosphere, and the acrylic resin obtained by the reaction at 70 ° C. for 5 hours was diluted with ethyl cellosolve so that the resin concentration became 10%.

A pigment (9.0 g) and a dispersant (0.9 g) were added to the diluted resin (90.1 g), and the mixture was sufficiently kneaded with a three-roll mill to prepare red, green and blue varnishes. The pigments and dispersants are shown below.

(For red filters) Pigment Riotogen Red GD (CI Pigment Red 168 manufactured by Toyo Ink Mfg. Co., Ltd.) 6.75g and Lionogen Orange R
(CI Pigment Orange 36 manufactured by Toyo Ink Mfg. Co., Ltd.)
Mixture with 2.25g Dispersant Compound of the following structural formula (For green filters) Pigment Lionol Green 2YS (C. by Toyo Ink Mfg. Co., Ltd.)
I. Pigment Green 36) 6.75g and Rionogen Yellow 3
G (CI Pigment Yellow 154 manufactured by Toyo Ink Mfg. Co., Ltd.)
Mixture with 2.25g Dispersant Copper phthalocyanine derivative CuPC [SO ₂ N (C ₁₈ H ₃₇ ) ₂ ] ₂ (for blue filter) Pigment Rionol Blue ES (Toyo Ink Mfg. Co., Ltd. CI Pigment Blue 15: 6) ) 7.2g with Rionogen Violet
HR (CI Pigment Violet 23 manufactured by Toyo Ink Mfg. Co., Ltd.) 1.8g mixture Dispersant Copper phthalocyanine derivative below Trimethylolpropane triacrylate (monomer) 4.0g benzyl dimethyl ketal for 100g of each colored resin
0.8 g was added and well stirred to give a colored composition.

First, γ-glycidoxypropylmethyldiethoxysilane was spin-coated on a substrate and spin-dried well. The blue composition was spin-coated (1100 rpm, 40 seconds) and dried. After prebaking at 70 ° C. for 20 minutes, a 5% solution of polyvinyl alcohol was coated. After drying at 70 ° C. for 20 minutes, exposure (1.500 mj / cm ² ) was performed using a mask having a pixel size of 30 μm × 100 μm. After development with a 2.5% sodium carbonate solution, the product was thoroughly washed with water. Since the pigment was attached to the substrate, the rubbing pigment was removed with a soft sponge. After further washing with water,
After spin drying, the pattern was fixed by baking at 230 ° C. for 1 hour. The green and red colors were similarly fixed using each composition to complete a color filter.

A 5% melamine epoxy resin (manufactured by Toyo Ink Co., Ltd.) was coated on this color filter, and baked at 230 ° C. for 120 minutes to give an overcoat.

<Effects of the Invention> Conventionally, it was not possible to obtain a composition having good dispersibility and high transparency with an acrylic resin and a pigment. However, by using a pigment derivative as a dispersant, a composition having good transparency could be obtained. According to the present invention,
By using the pigment and the acrylic resin, a high-definition color filter having excellent heat resistance and light resistance can be prepared. By using this color filter in a liquid crystal display device, it exhibits bright and excellent color characteristics. Further, the present invention is extremely excellent in practical use because it can sufficiently withstand the heat treatment required during the manufacturing process of the liquid crystal display device.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a general liquid crystal display device, FIG. 2 is a graph showing the spectral characteristics of a color filter prepared in an example of the present invention, and FIG. )
(C) is an explanatory view showing an embodiment of the method for manufacturing the color filter of the present invention in the order of steps, and FIG. 4 is an explanatory view showing an embodiment of the color filter of the present invention provided with a light shielding film. Is.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeo Sugiura 1-5-1 Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd.

Claims (5)

[Claims] 1. A substrate is coated with a colored resin composition containing an acrylic resin, an organic dye, a dispersant, and a solvent as main components, and the colored resin composition is provided in a desired pattern shape with an arbitrary number of colors for each color. In the color filter, the main component of the acrylic resin monomer has the general formula: (However, R = H or CH ₃ , n, m = 0, an integer of 0 to 6), and the composition ratio thereof is (a) 5 to 30 parts by weight, (b) 20 to 40.
A color filter, characterized in that (c) 40 to 60 parts by weight of a copolymer acrylic resin is used. 2. The color filter according to claim 1, wherein the dispersant is an organic dye derivative. 3. The color filter according to claim 1, wherein an overcoat layer is provided on the color filter. 4. A substrate is coated with a photo-curable coloring composition containing an acrylic resin, an organic dye, a dispersant and a solvent as a main component for each color, and the composition is repeatedly coated, exposed and developed in a desired pattern, and heated. A method for producing a color filter by firing to form a colored layer, wherein the main component of the acrylic resin monomer is represented by the general formula: (However, R = H or CH ₃ , n, m = 0, an integer of 0 to 6), and the composition ratio thereof is (a) 5 to 30 parts by weight, (b) 20 to 40.
A method for producing a color filter, characterized in that (c) 40 to 60 parts by weight of a copolymer acrylic resin is used. 5. The method for producing a color filter according to claim 4, wherein the dispersant is an organic dye derivative.