JP2937208B2 - Color filter and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention can provide a suitable color filter by being provided in a liquid crystal cell of a color liquid crystal display device. More specifically, a TN (twisted nematic) type liquid crystal display and a GH (guest) The present invention relates to a color filter for color separation suitable for a (host) type liquid crystal display and an FLC (ferroelectric liquid crystal) display device, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a color filter is obtained by purifying an organic natural product (gelatin, casein, etc.) that can be dyed and decomposing it into low molecules (10,000 to 50,000). Since this organic matter is soluble in water, a color filter was prepared by repeating coating, patterning, dyeing and baking of an aqueous solution for each coloring. However, the chromosome has a drawback that it is weak in heat resistance because it is a natural product, and it is also weak in light resistance because it uses a dye. On the other hand, in order to improve heat resistance and light resistance, various uses of pigments have been studied, but there is a problem in the dispersibility of the pigment, and a practical color filter having high uniformity and high transparency is produced. It was difficult to do. As for heat resistance, vapor deposition of a transparent electrode for operating a liquid crystal on a color filter, coating and firing of a polyimide resin for aligning the liquid crystal are performed, and a material that can withstand this is required.

[0003] On the other hand, when used in the field or on a vehicle, the light resistance may be directly received by sunlight, and high light resistance has been desired.

In view of the above-mentioned problems of the prior art, a Japanese Patent Application No. Sho-63-78139 has been proposed to provide a color filter having excellent heat resistance and light resistance, and also having excellent dispersibility and light transmittance of a dye. JP-A-63-299245 proposes a color filter manufactured using a coloring composition containing an acrylic resin, an organic dye, a dispersant and a solvent as main components. However, in the structure of the color filter, a high temperature treatment is required in post-baking in order to fix the pattern and obtain a certain level of resistance, and thus there is a problem in terms of workability and production cost.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a color filter capable of treating post-baking at a lower temperature than before and a method of manufacturing the same. It is in.

[0006]

In order to achieve the above object, a color filter according to the present invention is provided on a substrate by photocuring mainly comprising an acrylic resin, an organic dye, a dispersant, a thermal crosslinking agent and a solvent. It is characterized in that a colored layer is provided for each color in a desired pattern shape with an arbitrary number of colors by using a colored composition having a characteristic property. The use of a melamine resin or an epoxy resin as the thermal crosslinking agent is a particularly preferred embodiment of the present invention.

[0007] In such a method for producing a color filter, a photocurable coloring composition mainly composed of an acrylic resin, an organic dye, a dispersing agent, a thermal crosslinking agent and a solvent is coated on a substrate, and partially exposed. -It is characterized in that it is repeatedly applied for each color in a desired pattern by a development process, and then heated and baked to form a colored layer.

Hereinafter, the present invention will be described in more detail.

FIG. 3 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 passes through the polarizing plate 2 and the transparent substrate 3, passes through the pixel electrode 4 and the alignment film 5, advances to the liquid crystal 6, further passes through the alignment film 8 and the transparent electrode 9, and passes through the color filter. It is separated into three primary colors at 10. Further, the light passes through the transparent substrate 11 and the polarizing plate 12 and is recognized as a color by visual perception. In such a display device, the liquid crystal 6 is sealed in contact with the alignment films 5 and 8 and the sealing material 7 and changes its alignment direction by an electric signal applied between the pixel electrode 4 and the transparent electrode 11. . At this time, polarizing plates 2 and 12
Acts as an optical shutter, and the light passing through the color filter is turned 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 several tens to several hundreds of micrometers square for a handy display. It must be made of a material that can be finely processed.

Next, the structure of the color filter of the present invention will be described.

As shown in FIG. 3, as the transparent substrate 11, a glass substrate, a 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 the 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 a color filter may be located thereon.

As shown in FIG. 3, the color filter 10 includes, for example, a red filter layer R, a green filter layer G,
It consists of a blue filter layer B. In some cases, a black or opaque light-shielding layer or a non-colored layer may have R,
It may be provided between G and B. The red filter layer R is mainly composed of an acrylic resin, a red pigment, a dispersant, a thermal crosslinking agent, and the like. Hereinafter, similarly, the green filter layer G and the blue filter layer B are also composed mainly of an acrylic resin, a pigment, a dispersant, a thermal crosslinking agent and the like. The role of the acrylic resin is to fix each color pigment on the transparent substrate 11 and to make it possible to form a pattern in an arbitrary shape as needed, and to form the transparent electrode 9 on the color filter 10. It becomes a base material. The pigment of each color is
Since it plays a role of decomposing white light, it must have excellent transparency, light resistance and heat resistance. The primary particle size of the pigment is 0.3 μm or less, preferably 0.1 μm or less, which is sufficiently small with respect to the wavelength of visible light. Furthermore, an organic pigment is desirable as a pigment having excellent transparency. The dispersant is added to prevent aggregation of the pigment and to uniformly disperse the pigment in the acrylic resin. Therefore, the dispersant also has heat resistance and must not inhibit the properties of the color filter 10. Organic pigment derivatives of pigments or dyes are extremely effective as dispersants meeting this purpose. The dispersant need not be limited to the derivative of the pigment, but may be a cationic surfactant, an anionic surfactant, a nonionic surfactant, or the like. The weight ratio of the pigment to the acrylic resin 1 is usually preferably in the range of 0.25 to 3. When the pigment ratio 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. When the ratio of the pigment is increased, the dispersibility and coatability of the pigment are significantly deteriorated. The weight ratio of the dispersant to the pigment is preferably 0.01 to 0.2, but it is not necessary to limit to this value. The film thickness of the color filter having the above composition was 0.75 μm to 3.0 μm. FIG. 4 shows typical spectral characteristics of the color filter thus prepared.

[0013] Examples of the thermal crosslinking agent preferably used in the present invention include melamine resins and epoxy resins.

The melamine resin includes an alkylated melamine resin (eg, a methylated melamine resin, a butylated melamine resin), a mixed etherified melamine resin, and the like, and may be a high condensation type or a low condensation type. These melamine resins are commercially available from Sanwa Chemical Co., Ltd. and Sumitomo Chemical Co., Ltd.

Examples of the epoxy resin include glycerol / polyglycidyl ether, trimethylolpropane / polyglycidyl ether, resorcin / diglycidyl ether, neopentyl glycol / diglycidyl ether, 1.6-hexanediol / diglycidyl ether, ethylene Glycol (polyethylene glycol)
There are diglycidyl ethers, and these epoxy resins are commercially available from Nagase Kasei Co., Ltd. and Nippon Kayaku Co., Ltd.

The addition amount of the thermal crosslinking agent is preferably in the range of 5 to 70% by weight, more preferably 10 to 40% by weight, based on the amount of the acrylic monomer.

The acrylic monomer for constituting the acrylic resin that can be used in the present invention includes:

[0018]

Embedded image (R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl, branched alkyl, or each group such as phenyl, cyclohexyl, tetrahydrofurfuryl, etc.), but is mainly used in the present invention. Specific examples of the resin monomer include the following.

[0019]

Embedded image

In the present invention, it is needless to say that the resin is not limited to these, but is a resin synthesized from several kinds of monomers selected as necessary from these. In addition, monomers that can change the properties of the resin by adding a small amount when synthesizing the resin include dimethylaminoethyl methacrylate, benzyl acrylate, glycidyl methacrylate, acrylonitrile, vinyl acetate, N-vinylpyrrolitron, and tetrahydrofurfuryl methacrylate. There is.

As the solvent, methyl cellosolve, ethyl cellosolve, cyclohexanone, xylene and the like are good, and a mixture of these solvents may be used, but cyclohexanone and methyl cellosolve are particularly preferable from the viewpoint of solubility.

As the dye according to the present invention, a dye or a pigment can be used, but a pigment is desirable from the viewpoint of heat resistance and light resistance. Examples of heat-resistant pigments include barium sulfate, pencil, lead sulfate, titanium oxide, yellow lead, red iron oxide, ultramarine, navy blue, chromium oxide, inorganic pigments such as carbon black, benzidine yellow G, benzidine yellow GR, Lithol first orange 3GL, Vulcan first orange GG, pigment scarlet 3B, thioindigo maroon, phthalocyanine blue, phthalocyanine green, indanthrene blue, green gold, macalite green lake, and the like. Specifically, the color index (CI) number is shown below.

C. I. Yellow pigment 20, 24, 86,
93, 109, 110, 117, 125, 137, 138, 147, 148, 153, 1
54, 166, 168 C.I. I. Oren pigment 36, 43, 51, 55, 59, 61 C.I. I. Red pigment 9, 97, 122, 123, 149, 1
68, 177, 180, 192, 215, 216 or 217, 220, 223, 22
4, 226, 227, 228, 240 C.I. I. Violet pigments 19, 23, 29, 30, 37, 40,
50 C.I. I. Blue pigment 15, 15: 6, 22, 60, 64 C.I. I. Green pigment 7, 36 C.I. I. Brown pigment 23, 25, 26 C.I. I. Black pigment 7

The dispersant according to the present invention is a derivative of an organic dye. Examples of the organic dye serving as a base include azo, phthalocyanine, quinacridone, anthraquinone, perylene, perinone, thioindigo, dioxazine, and the like.
Isoindolinones, quinophthalones, triphenylmethanes, metal complex salts and the like. Derivatives having substituents on these organic dyes and effective in dispersing the dyes are used.
The substituent is a hydroxyl group, a carboxyl group, a sulfonic acid group, a carbonamide group, a sulfonamide group, or any of the substituents represented by the following general formula. Derivatives having at least one substituent selected from these substituents are used.

[0025]

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

[0026]

Embedded image (X: alkylene group, R ₁ , R ₂ : hydrogen atom or alkyl group, or heterocycle containing at least nitrogen atom in R ₁ and R ₂ )

[0027]

Embedded image (R ₁ : hydrogen atom, alkyl group or aryl group, R ₂ :
An alkyl group or an aryl group or a heterocycle containing at least a nitrogen atom in R ₁ and R ₂ )

[0028]

Embedded image (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 at least a nitrogen atom between R ₂ and R ₃ Including heterocycle)

The pigment and the parent organic pigment of the dispersant are usually combined in the same color in terms of hue.
They do not have to match.

In the composition of the present invention, the composition ratio is not particularly limited.
About 50% by weight, and 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 based on the acrylic resin, and the dispersant depends on the type of the pigment and the like. 0.1-30% by weight based on pigment
It is about. Further, the coloring composition of the present invention can be used as a color concentrate having a high pigment content. In addition, additives can be blended as needed.

In order to prepare a composition or the like according to the present invention, an acrylic resin, a solvent, a dye, a dispersant, and a thermal crosslinking agent are dispersed and mixed by a roll mill, a ball mill, a sand mill, an attritor, and other dispersing and mixing devices. . Alternatively, it can be prepared by dispersing an acrylic resin, a pigment, a dispersant, and a thermal crosslinking agent in advance by a roll mill or the like, and then diluting the dispersion with a solvent or a varnish of an acrylic resin and a solvent.
Alternatively, the pigment and the dispersant may be mixed, and then mixed and dispersed with a varnish or the like. Note that the order of mixing and dispersion is not limited to this, and can be appropriately performed.

In order to impart photocuring properties to the colored composition of the present invention, there are two types: a crosslinking method and a polymerization method.

When the colored composition of the present invention is photocured by a crosslinking method, various azide compounds can be used as a photocrosslinking agent to be added. For example, 1.3-bis (4'-azidobenzal) -2-propane, 1.3-bis (4'-azidobenzal) -2-propane-2'-sulfonic acid,
There are 4.4'-diazidostilbene-2,2'-disulfonic acid and the like, but from the viewpoint of solubility, 4.4-diazidostilbene-2,2'-disulfonic acid is preferable. In the case of photocuring by a polymerization method, it can be variously used as a monomer to be added and a photopolymerization initiator. Monomers include bifunctional and trifunctional monomers. As the bifunctional monomers, 1.6-hexanediol diacrylate, ethylene glycol diacrylate, neopentyl glycol diacrylate, triethylene glycol diacrylate, bis (acryloxyethoxy) bisphenol A, 3-methylpentanediol diacrylate and the like, and trifunctional monomers include trimethylol propatone acrylate, pentaerythritol triacrylate, tris (2-hydroxyethyl) isocyanate and the like. Co., Ltd., Toagosei Co., Ltd., Celanese Chemical Co., Ltd., and the like. Examples of the photopolymerization initiator include acetophenone, benzophenone benzyl dimethyl ketal, benzoyl peroxide, 2-chlorothioxanthone, and the like. Daito Chemical Industry Co., Ltd., Nissin Chemical Co., Ltd., Ciba Geigy,
There are commercial products from Osaka Organic Chemical Industry Co., Ltd. and others. In order to improve the adhesion between the substrate and the composition, various commercially available primers may be added to the composition, or the composition may be coated on the substrate in advance and dried.

The method for producing a color filter of the present invention comprises:
A step of adding a pigment and a dispersant to the acrylic resin, kneading the mixture sufficiently with a stirrer such as a three-roll to make a varnish for each color, and adding a photocrosslinking agent or a photopolymerization initiator and an acrylic monomer and a thermal crosslinker to this composition. Adding, applying the colored varnish to a transparent substrate after patterning, or applying in a pattern and heating and condensing to form a colored filter layer comprising an acrylic resin, a pigment, a dispersant and a thermal crosslinking agent,
If necessary, the above steps are repeated to form a color filter having a combination of two or more hues.

Here, the acrylic resin is a pigment dispersion medium, and the dispersant is an auxiliary agent for uniformly dispersing the pigment in the acrylic resin. The pigment and the dispersant are added to the acrylic resin and sufficiently kneaded with a three roll or the like to produce a varnish for each color. Next, as shown in FIGS. 1A to 1C, the colored varnish, for example, a red varnish is applied on the transparent substrate 14 by a spinner, a roll coater or the like. Next, the solvent is removed at a temperature of 230 ° C. or less to form a dried film of the colored varnish, that is, a colored coating film 13 (see (a)). Next, using a super-high pressure mercury lamp, etc., partially expose through a mask and develop to develop a colored layer.
15 relief patterns are formed (see (b)). This operation is further repeated twice to form R, G, B in FIG. 1 (c). FIG. 2 shows that a gap is provided between the colored layers 15, and a black colored composition is used between the colored layers 15. A light-shielding film 16 having a stripe or lattice pattern is provided.

[0036]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples.

An acrylic resin (20 parts of methacrylic acid, 25 parts of cyclohexyl acrylate, and 55 parts of methyl methacrylate) is dissolved in 300 parts of ethyl cellosolve, and 0.75 parts of azobisisobutyronitrile is added under a nitrogen atmosphere, and the mixture is reacted at 70 ° C. for 5 hours. The resulting acrylic resin was diluted with ethyl cellosolve to a resin concentration of 10%. 90.1 g of this diluted resin
Then, 9.0 g of a pigment and 0.9 g of a dispersant were added, and the mixture was sufficiently kneaded with a three-roll mill to prepare red, green, and blue varnishes. Less than,
1 shows a pigment and a dispersant.

(For red filter) Pigment Riotogen Red GD (C.I.
I. A mixture of 6.75 g of CI Pigment Red 168) and 2.25 g of Lionogen Orange R (CI Pigment Orange 36, manufactured by Toyo Ink Mfg. Co., Ltd.) Dispersant Compound of the following structural formula

[0039]

Embedded image

(For green filter) Pigment Lionol Green 2YS (manufactured by Toyo Ink Mfg. Co., Ltd.)
C. I. Pigment Green 3G 6.75 g and Lionogen Yellow 3G (CI Pigment Yellow 154 manufactured by Toyo Ink Mfg. Co., Ltd.) 2.25 g Dispersant Copper phthalocyanine (PC) derivative shown below

(For Blue Filter) Pigment Lionol Blue ES (C.I.
I. Pigment Blue 15: 6) 7.2 g and a mixture of 1.8 g of Lionogen Violet RL (CI Pigment Violet 23 manufactured by Toyo Ink Mfg. Co., Ltd.) Dispersant The following copper phthalocyanine derivative

[0042]

Embedded image

For 100 g of each colored resin, 4.0 g of trimethylolpropane triacrylate (monomer), 0.8 g of benzyl dimethyl ketal as a photopolymerization initiator, and a thermal crosslinking agent shown in Table 1 (the amount of addition is 30% by weight of the monomer amount) Was added and stirred well to obtain a colored composition.

First, 2-glycidoxypropylmethyldiethoxysilane was spin-coated on a substrate and spin-dried well. Spin-coat the blue composition (1100r.p.
m, 40 seconds) and dried. After prebaking at 70 ° C. for 20 minutes, a 5% solution of polyvinyl alcohol was coated to form an oxygen barrier film. After drying at 70 ℃ for 20 minutes, pixel size 30μm × 1
Exposure (1,500 mJ / cm ² ) was performed using a 00 μm mask. 2.
After development with a 5% sodium carbonate solution, the resultant was thoroughly washed with water. Since the pigment was attached to the substrate, the rubbed pigment was removed with a soft sponge. After washing with water and spin drying,
The pattern was fixed by post-baking for an hour. Green and red were similarly fixed using each composition to complete a color filter.

A color filter was prepared in exactly the same manner as above except that the post-baking conditions were changed to 170 ° C. for 1 hour, 200 ° C. for 1 hour, and 200 ° C. for 3 hours.

Further, a color filter was prepared in the same manner as described above except that no thermal crosslinking agent was added to the coloring composition, and used as a comparative sample.

Each of the produced color filters was evaluated for its appearance by immersing in a 5% aqueous sodium hydroxide solution in order to evaluate the durability of the pattern. In particular,
Each color filter was immersed in a 5% aqueous sodium hydroxide solution at room temperature for 30 minutes, washed with water, dried by blowing nitrogen gas, and the appearance of the processed pattern was observed using a microscope. Table 1 shows the results. In the table, ○ indicates no change in appearance, Δ indicates partial peeling by spraying with nitrogen gas (can be used without any problem in practical use), and × indicates total peeling (cannot be used). .

[0048]

[Table 1] * A Methylated melamine resin B Methylated melamine resin C Glycerol diglycidyl ether D Sorbitol polyglycidyl ether E Ethylene glycol diglycidyl ether F Diethylene glycol diglycidyl ether

As is clear from the results shown in Table 1, the comparative sample No. 7 to which no thermal crosslinking agent was added required a treatment at 230 ° C. for 1 hour, and a treatment at a lower temperature of 200 ° C. for 3 hours. However, the curing of the resin does not proceed and the required resistance cannot be obtained. On the other hand, in the samples Nos. 1 to 6 of the present invention to which the thermal crosslinking agent was added, the required resistance was obtained even at 200 ° C. for 1 hour, and the post-baking treatment at a lower temperature than before was possible.

[0050]

As described above in detail, according to the present invention, by containing a thermal crosslinking agent in a coloring composition,
Post-baking for fixing the pattern and obtaining a certain resistance can be performed at a lower temperature than in the past, resulting in extremely excellent effects in practical use, such as improved workability and advantageous in terms of production cost. .

[Brief description of the drawings]

FIG. 1 shows an embodiment of a color filter of the present invention,
(A)-(c) is sectional drawing which shows an example of the manufacturing method in order of a process.

FIG. 2 is a sectional view showing another embodiment of the color filter of the present invention.

FIG. 3 is a cross-sectional view illustrating an example of a liquid crystal display device.

FIG. 4 is a diagram showing an example of the spectrum of the color filter of the present invention.

[Explanation of symbols]

 10 Color filter 13 Color coating film 14 Transparent substrate 15 Color layer

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02B 5/20 101

Claims (6)

(57) [Claims] 1. An acrylic resin, an organic dye,
A color filter comprising a photocurable coloring composition containing a dispersant, a thermal crosslinking agent and a solvent as main components, and provided with a coloring layer for each color in a desired pattern shape with an arbitrary number of colors. 2. The color filter according to claim 1, wherein the thermal crosslinking agent is a melamine resin. 3. The color filter according to claim 1, wherein said thermal crosslinking agent is an epoxy resin. 4. An acrylic resin, an organic dye,
Coating a photocurable coloring composition containing a dispersant, a thermal crosslinking agent and a solvent as main components, repeatedly applying a desired pattern to each color by a partial exposure / development process, and heating and baking to form a colored layer. A method for producing a color filter, comprising: 5. The method according to claim 4, wherein the thermal crosslinking agent is a melamine resin. 6. The method according to claim 4, wherein the thermal crosslinking agent is an epoxy resin.