JP3196638B2 - Resin black matrix, black paste, color filter and liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin black matrix used for a color filter of a liquid crystal display device and a black paste for producing the same. TECHNICAL FIELD The present invention relates to a resin black matrix having excellent characteristics such as high precision and little occurrence of film peeling, and a black paste for producing the same.

[0002]

2. Description of the Related Art In general, a color filter for a liquid crystal display is
Pixels of three primary colors, red, green and blue, formed on a light transmitting substrate are composed of a large number of picture elements as one picture element. A light-shielding region having a certain width (referred to as a black matrix because it generally looks black on a screen) is provided between the pixels to enhance the display contrast.

A conventional color filter utilizes a black matrix prepared by a photolithography method in advance, and is often formed of a metal thin film having a fine pattern. The metal used for the black matrix includes Cr, Ni, Al and the like, and as a forming method thereof, a vacuum thin film forming method such as a sputtering method or a vacuum evaporation method is widely used. Next, in order to form a fine pattern, a photoresist pattern is usually formed by a photolithography method, and then the metal thin film is etched using the resist pattern as an etching mask. Through this step, a fine pattern of the metal thin film that matches the fine pattern of the photoresist can be formed.

In addition, as a method of forming a pixel, a method of dyeing a dyeable medium formed by photolithography, a method of using a photosensitive pigment dispersion composition, and a method of etching a non-photosensitive pigment dispersion composition Besides the electrodeposition method using a patterned electrode and the like, there is also a low-cost manufacturing method in which a colored portion is formed by a printing method or an inkjet method.

[0005]

However, the black matrix formed of the metal thin film has a high manufacturing cost in the process of forming the metal thin film, and causes a rise in the price of the color filter itself. Furthermore, Cr, which is generally used as a metal thin film for a black matrix, has a high reflectivity, and therefore, C may be used in places where external light is strong.
The reflected light from the r-plane is also strong, and when a color filter is incorporated in a transmission type display, there is a problem that display quality is significantly impaired. In order to lower the reflectance of the black matrix, a method of providing a layer such as chromium oxide between Cr and a light-transmitting substrate has been proposed,
The production cost of the black matrix is further increased, which is not preferable from the viewpoint of cost reduction.

For this reason, a method has been proposed in which, for example, a resin colored by a light-shielding agent is patterned to form a black matrix, and then pixels are formed to produce a color filter. However, sufficient light-shielding properties have not yet been obtained as compared with conventional metal thin films. Therefore, in the liquid crystal display, there is a problem that the backlight light leaks to the display surface through the black matrix. Therefore, there is a serious problem that a desired color cannot be displayed, particularly when displaying black or a color with low luminance. On the other hand, in order to improve the light-shielding property, the thickness of the black matrix may be increased, but this time, a new problem arises in that the flatness of the color filter surface is reduced and the image quality is reduced.

The present invention has been made in view of the above-mentioned drawbacks of the technology, and has as its object to provide a color having a high light-shielding property and capable of displaying excellent image quality when incorporated in a liquid crystal display device. The present invention relates to a resin black matrix for a filter and a black paste for producing the same.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
This can be achieved by the following resin black matrix and a black paste for producing the same.

That is, in a resin black matrix in which a light-shielding agent is dispersed in a non-photosensitive polyimide resin, carbon black satisfying at least one of the following (A) to ( C ) is used as the light-shielding agent. In a resin black matrix, a black paste obtained by dispersing a light-shielding agent in a non-photosensitive polyimide precursor solution, carbon black that satisfies at least one of the following (A) to ( C ) is used as the light-shielding agent: And a color filter having the resin black matrix, and a liquid crystal display device having the color filter .

(A ) Surface carboxyl group concentration [COO
H] is 0.001 <
[COOH].

( B ) The hydroxyl group concentration [OH] on the surface satisfies 0.001 <[OH] in a molar ratio per total carbon atoms.

( C ) Sulfone group concentration on the surface [SO ₃ H]
Has a molar ratio of 0.001 <[SO
_[ 3H].

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail.

In the black matrix of the present invention, it is necessary to finely disperse carbon black in order to obtain a high light-shielding property, and a specific carbon black is dispersed in a resin as a light-shielding agent. What is specific carbon black?
The carbon black satisfies at least one of the following (A) to ( C ) .

(A ) Surface carboxyl group concentration [COO
H] is 0.001 <
[COOH].

( B ) The hydroxyl group concentration [OH] on the surface satisfies 0.001 <[OH] in a molar ratio per total carbon atoms.

( C ) Sulfone group concentration on the surface [SO ₃ H]
Has a molar ratio of 0.001 <[SO
_[ 3H] .

[0018] The carboxyl group concentration of the front surface [COOH]
Is more preferably 0.002 or more, further preferably 0.003 or more, from the viewpoint of dispersion stability. Although the upper limit is not particularly limited, usually [COOH] =
0.1 is the upper limit in the production of carbon black.

The hydroxyl group concentration [OH] on the surface is more preferably 0.002 or more, and still more preferably 0.002 or more.
It is desirable to be 3 or more from the viewpoint of dispersion stability. The hydroxyl group includes a neutral alcoholic hydroxyl group and an acidic phenolic hydroxyl group, and the amount of the phenolic hydroxyl group is important. Therefore, the concentration of the phenolic hydroxyl group is preferably 50% or more of the concentration of the hydroxyl group. The concentration of the phenolic hydroxyl group is preferably 0.005 or more. In addition, the surface hydroxyl group concentration [O
H] is not particularly limited, but usually [OH] = 0.
1 is the upper limit in the production of carbon black.

The sulfone group concentration on the surface [SO ₃ H]
Is more preferably 0.002 or more, further preferably 0.003 or more, from the viewpoint of dispersion stability. Although the upper limit is not particularly limited, usually [SO ₃ H] =
0.1 is the upper limit in the production of carbon black.

As a method for quantifying the hydroxyl group concentration, carboxyl group concentration and sulfone group concentration on the carbon black surface, X-ray photoelectron spectroscopy called XPS or ESCA can be used. In particular, it is effective to use X-ray photoelectron spectroscopy in combination with the chemical modification method. For example, in order to distinguish between a carboxyl group and a hydroxyl group, labeling is performed by reacting a hydroxyl group with trifluoroacetic anhydride or the like, and F is detected by X-ray photoelectron spectroscopy.
The hydroxyl group concentration can be quantified by the 1S peak intensity. The carboxyl group can be labeled by reacting the carboxyl group with trifluoroethanol or the like, and the carboxyl group concentration can be quantified by the F1S peak intensity detected by X-ray photoelectron spectroscopy.

Examples of a method for providing a hydroxyl group or a carboxyl group on the surface of carbon black include: a method of producing carbon powder and oxidizing it by contacting it with free oxygen at a high temperature; a method of oxidizing with an oxidizing agent such as ozone and NO ₂ ; There is a method of treating with bromine and water under normal pressure or pressure, a method of oxidizing with an oxidizing solution such as nitric acid or sulfuric acid, etc.
Provide an acidic group such as a phenolic hydroxyl group. Further, these methods may be combined. Further, an acidic group such as a sulfone group can be provided by a chemical reaction such as sulfonation with fuming sulfuric acid .

[0023] mosquitoes over carbon black, channel black,
Roller black, manufactured by contact method called disk black, gas furnace black, manufactured by furnace method called oil furnace black, thermal black, called acetylene black Any of those produced by a thermal method can be used, but channel black, gas furnace black, and oil furnace black are preferable, and furnace black is particularly preferable.

In order to improve the light-shielding properties of the black matrix, it is preferable to use carbon black having a small particle diameter, and the average primary particle diameter is preferably 5 to 40 nm.
More preferably 6 to 35 nm, further preferably 8 to 3 nm.
0 nm.

The structure of carbon black in the black matrix is such that fine carbon black is aggregated to form secondary particles of carbon black. It is preferable to finely disperse the particles so as to reduce the secondary particle diameter, and ideally to disperse the primary particles with good stability without forming secondary particles. The average secondary particle size is preferably from 5 to 100 nm, more preferably from 6 to 88 nm, and still more preferably from 8 to 88 nm.
７５75 nm. If it is larger than this, a sufficient light shielding property cannot be obtained, which is not preferable. The average primary particle size and the average secondary particle size are determined, for example, by observing carbon black with a transmission or scanning electron microscope or the like, and using JIS-R6002.
The average particle size is determined according to the above.

Such a carbon black having a small particle size has a color tone mainly of a tea system. Therefore, it is preferable to mix a complementary color pigment with carbon black to make it achromatic. As a resin black matrix,
It is preferable that a light-shielding agent composed of carbon black and a complementary color pigment is dispersed in the resin. The complementary color of brown is blue or purple. As the complementary color pigment, a blue pigment or a violet pigment,
Further, a mixture of a blue pigment and a violet pigment can be used. However, when a colored resin is used, a pigment that is a complementary color to the mixed color of the resin and carbon black is used.
Specific examples of typical pigments are shown by Color Index (C
I) Indicate by number. As the blue pigment or the violet pigment, an organic pigment having a high tinting strength is particularly preferable, and examples of the blue pigment include Pigment Blue 15, 15: 1, and 15:
2, 15: 3, 15: 4, 15: 6, 16, 21, 2
Pigment Blue 15, 15: 1, 15: 2 and 15: 6 are particularly preferred.
Pigment Violet 19, 2
3, 29, 31, 32, 33, 36, 37, 39, 4
Pigment Violet 23, 31, 33, 43, and 50 are particularly preferred.

In addition to the above, various light-shielding agents may be added as long as the light-shielding property is not deteriorated. However, in order to obtain high light-shielding properties, the proportion of carbon black in the light-shielding agent must be 50% by weight. % Or more, more preferably 60% by weight or more, even more preferably 70% by weight or more. As a light-shielding agent other than carbon black, a mixture of pigments such as red, blue, and green can be used in addition to metal oxide powder such as titanium oxide and iron tetroxide, metal sulfide powder, and metal powder.

As the achromatic resin black matrix of the present invention, a C light source or F1 in the XYZ color system
The chromaticity coordinates (x, y) of the transmitted light and the reflected light of the resin black matrix measured at the light source ₀ are the chromaticity coordinates (x ₀ ) of the light source. , Y ₀ ) With respect to (xx ₀ ) ² + (y
−y ₀ It is preferable that ² ≦ 0.01, more preferably (xx− _0). ) ² + (y−y ₀ ) ² <0.002
5, more preferably (xx- ₀ ) ² + (y−y ₀ ) ² <
0.0004.

In addition, the color liquid crystal display device has a normal visibility.
A backlight light source for improvement is provided. Departure
Ming resin black matrix, when illuminated by backlight
Through the resin black matrix on the liquid crystal display
Chromaticity coordinates of the leaking light in the XYZ color system (x,
y) is the chromaticity coordinates (x₀ , Y₀ ) To
And (xx₀ )^Two+ (Y-y₀ )^Two≦ 0.01
And more preferably (xx₀ )^Two+
(Yy₀ )^Two<0.0025, more preferably (x-
x₀ )^Two+ (Y-y₀ )^Two<0.0004.

As the backlight, a three-wavelength light source whose energy concentrates on the peak of the transmission spectrum of the red, blue and green pixels of the color filter is usually used. The three-wavelength light source has strong light energy peaks at three specific wavelengths in the visible region (400 to 700 nm), and this is called the main wavelength. The dominant wavelength is defined as the center of the highest energy of the blue light in the wavelength range of 400 to 490 nm, ± 10 nm around the peak, and the highest energy in the green color in the wavelength range of 490 to 580 nm. For reddish light in the range of ± 10 nm around the peak and in the wavelength range of 580 to 675 nm, the range of ± 10 nm is around the peak with the highest energy. Usually 440-460 nm, 530-55
0 nm, in the range of 600 to 620 nm.

The transmittance of the resin black matrix at each of these main wavelengths is preferably such that the maximum value does not exceed four times the minimum value, more preferably does not exceed two times, and further preferably 1. Preferably it does not exceed 5 times. If the difference is larger than this, the light leaked through the three-wavelength light source will be colored, and image display quality will be impaired. However, the transmittance of the resin black matrix at each dominant wavelength is an average value at three points of +10 nm and -10 nm centering on the highest energy peak.

The black matrix has a wavelength of 430-6.
It is preferable that the black matrix has a light shielding property of an optical density of 2.3 or more per 1 μm of film thickness in a visible light region of 40 nm. It is more preferably at least 3.1, even more preferably at least 3.5. Hereinafter, wavelengths 430-6
The optical density per 1 μm of film thickness in a visible light region of 40 nm is defined as a light shielding property. In order to improve the light blocking effect,
It is important to improve the dispersion and dispersion stability of the light shielding agent. In order to obtain such a high light-shielding property, the proportion of carbon black contained in the black matrix is preferably 35% by weight or more, more preferably 45% by weight or more, and further preferably 60% by weight or more. Is desirable.

The primary stimulus Y in the XYZ color system of the black matrix in the visible light region having a wavelength of 400 to 700 nm is preferably 0.50 or less, more preferably 0.079 or less, and still more preferably 0.10 or less. 02
5 or less.

The thickness of the black matrix is 1
μm, more preferably 0.75 μm
μm or less, more preferably 0.5 μm or less. The smaller the thickness of the black matrix, the smaller the surface difference on the color filter, which is preferable. The protective layer can be omitted by setting the thickness of the black matrix to 0.5 μm or less, which is particularly preferable.
The lower limit is not particularly limited.
The above is preferred.

As the resin for the black matrix,
Examples include polyimide resin, acrylic resin, PVA, gelatin, polyester resin, and polyvinyl resin. It is preferable that the resin has higher heat resistance than the resin used for the pixel and the protective film, and a polyimide resin having heat resistance of 250 ° C. or higher is more preferable. Examples of the polyimide resin include, but are not particularly limited to, polyamide imide. Usually, a polyimide precursor (n = 1 to 2) containing a structural unit represented by the general formula (1) as a main component is heated or reacted with an appropriate catalyst. Those that are imidized are preferably used.

[0036]

Embedded image

In the above general formula (1), R ¹ is at least 2
A trivalent or tetravalent organic group having at least two carbon atoms. From the viewpoint of heat resistance, R ¹ contains a cyclic hydrocarbon, an aromatic ring or an aromatic heterocyclic ring, and has 3 to 6 carbon atoms.
A valent or tetravalent group is preferred. Examples of R ¹ include phenyl, biphenyl, terphenyl, naphthalene, perylene, diphenylether, diphenylsulfone, diphenylpropane, benzophenone,
Biphenyl trifluoropropane group, cyclobutyl group,
Examples include, but are not limited to, cyclopentyl groups.

R ² is a divalent organic group having at least two or more carbon atoms. From the viewpoint of heat resistance, R ² contains a cyclic hydrocarbon, an aromatic ring or an aromatic heterocyclic ring, and A divalent group having 6 to 30 carbon atoms is preferable.

Examples of R ² include phenyl, biphenyl, terphenyl, naphthalene, perylene, diphenylether, diphenylsulfone, diphenylpropane, benzophenone, biphenyltrifluoropropane, diphenylmethane, and dicyclohexylmethane. But not limited thereto.

The polymer having the structural unit (1) as a main component is
R ¹ and R ² may each be composed of one of them, or may be a copolymer composed of two or more of each. Furthermore, in order to improve the adhesion to the substrate, as a diamine component as long as the heat resistance is not reduced,
It is preferable to copolymerize bis (3-aminopropyl) tetramethyldisiloxane having a siloxane structure.

Specific examples of the polymer having the structural unit (1) as a main component include pyromellitic dianhydride, 3,3 ′,
4,4′-benzophenonetetracarboxylic dianhydride,
3,3 ', 4,4'-biphenyltrifluropropanetetracarboxylic dianhydride, 3,3', 4,4'-biphenylsulfonetetracarboxylic dianhydride, 2,3
One or more carboxylic dianhydrides selected from the group consisting of 5, -tricarboxycyclopentyl acetic acid dianhydride and the like, and paraphenylenediamine, 3,3′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, , 4 'diaminodiphenyl ether, 3,3'-
Polyimide precursor synthesized from one or more diamines selected from the group of diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodicyclohexylmethane, 4,4'-diaminodiphenylmethane But not limited thereto. These polyimide precursors are synthesized by a known method, that is, by selectively combining tetracarboxylic dianhydride and diamine and reacting them in a solvent.

Usually, a dicarboxylic anhydride such as maleic anhydride is added to seal the molecular end of the polyimide precursor and stop the polymerization. However, it is more preferable that the molecular terminal of the polyimide resin be an amine group because the dispersibility of the light-shielding agent is improved. The proportion at which the molecular terminal is an amine group is preferably 50% or more, more preferably 80% or more, and further preferably 90% or more. In order to make the molecular terminal of the polyimide resin an amine group, during the synthesis of the polyimide precursor, the molar number of the diamine is slightly increased with respect to the molar number of the tetracarboxylic dianhydride, and the reaction is performed in a solvent. Is preferred. Specifically, the tetracarboxylic dianhydride is preferably 100 to 90 mol, more preferably 98 to 93 mol per 100 mol of the diamine.
Mol, more preferably 97-95 mol.

Among these polyimide resins, those having higher light absorption at a wavelength in the visible light range are more preferable because the black matrix also has higher light-shielding properties. That is, in a polyimide film having a film thickness of 2 μm, a wavelength of 400 to
Primary stimulus Y in XYZ color system with 700 nm visible light
Is preferably 96 or less, more preferably 90 or less, and still more preferably 80 or less.

Specifically, for example, as the tetracarboxylic dianhydride, the higher the electron-withdrawing property of the acid dianhydride residue, the more preferable it is. A ketone type such as a benzophenone group and an ether type such as a diphenyl ether group are preferred. And those having a phenyl group and those having a sulfone group such as diphenylsulfone group are preferred. For example,
Pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4
And 4'-biphenyltetracarboxylic dianhydride. As the diamine, the electron donating property of the diamine residue is preferably as high as possible, and the biphenyl group, p-, p-substitution or m
Those having a diaminodiphenyl ether having a-, p-substituted structure, methylenedianiline, a naphthalene group, a perylene group or the like are preferable, and examples thereof include 4,4 'or 3,4'diaminodiphenyl ether and paraphenylenediamine. It is also preferable that these aromatic rings have a structure in which a nitro group is substituted.

The resin black matrix of the present invention can be formed by a coating method using a black paste in which a light-shielding agent comprising the specific carbon black is dispersed in a resin solution.

The average primary particle size and the average secondary particle size of the carbon black in the black paste can be determined, for example, by applying the black paste, drying, and then observing the carbon black with a transmission or scanning electron microscope. , JIS-R600
The average particle size is determined according to 2.

It is also preferable to mix a complementary color pigment with carbon black to make it achromatic. The black paste of the present invention may be prepared by adding carbon black and a complementary color pigment to the carbon black in a resin solution. It is preferable to disperse a light-shielding agent consisting of For example, a blue pigment or a violet pigment, or a mixture of a blue pigment and a violet pigment can be used, and an organic pigment having high coloring power is particularly preferable.

In addition to the above, various light-shielding agents may be added as a light-shielding agent as long as the light-shielding property is not reduced. However, in order to obtain a high light-shielding property, the proportion of carbon black in the light-shielding agent is 50% by weight. % Or more, more preferably 60% by weight or more, even more preferably 70% by weight or more. As a light-shielding agent other than carbon black, a mixture of pigments such as red, blue, and green can be used in addition to metal oxide powder such as titanium oxide and iron tetroxide, metal sulfide powder, and metal powder.

The color of the transmitted light of the black paste of the present invention is obtained by using a C light source or an F10 light source under the condition that the original stimulus Y satisfies 0.03 ≦ Y ≦ 0.3 in the XYZ color system. , The chromaticity coordinates (x, y) are the chromaticity coordinates (x ₀ , Y ₀ ) With respect to (xx ₀ ) ² + (y−
y ₀ It is preferable that ² ≦ 0.01, more preferably (xx− _0). ) ² + (y−y ₀ ) ² <0.0025,
More preferably, (xx ₀ ) ² + (y−y ₀ ) ² <0.
0004.

As a method of measuring the color of the transmitted light of the black paste, first, the light transmittance is measured. There are a method of applying a predetermined amount of black paste on glass and measuring the transmittance with a spectrophotometer, and a method of placing the black paste in a glass cell and measuring the transmittance with a spectrophotometer. From the light transmission spectrum, the original stimuli X, Y, Z in the C light source or F10 light source
Is calculated, and the chromaticity coordinates are calculated.

As the resin solution, a solution of a polyimide precursor, an acrylic resin, PVA, gelatin, a polyester resin, a polyvinyl resin or the like can be used. The polyimide precursor solution preferably has higher heat resistance than the resin used for the pixels and the protective film, and has a heat resistance of 250 ° C. or higher. As the polyimide precursor, the above-mentioned polyimide precursor can be preferably used.

Therefore, among the polyimide precursors,
In particular, those having higher light absorption at wavelengths in the visible light range are more preferable because the black matrix have higher light-shielding properties.
That is, in a 2 μm-thick polyimide film, XYZ
It is preferable to use a polyimide resin having a primary stimulus Y of 96 or less in the color system, more preferably 90 or less, and still more preferably 80 or less. These values are at a wavelength of 400
It can be calculated by measuring the light transmittance spectrum of the polyimide film in the visible light of ７００700 nm. Specifically, for example, as tetracarboxylic dianhydride, it is preferable that the electron-withdrawing property of the acid dianhydride residue is high, and a ketone type such as a benzophenone group, an ether type such as a diphenyl ether group, Those having a phenyl group and those having a sulfone group such as a diphenylsulfone group are preferred. For example, pyromellitic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, and the like. As the diamine, those having a stronger electron donating property of the diamine residue are preferable, and those having a biphenyl group, a diaminodiphenyl ether having a p-, p-substituted or m-, p-substituted structure, methylene dianiline, a naphthalene group, a perylene group, or the like are preferable. Preferred, 4,4
'Or 3,4' diaminodiphenyl ether, paraphenylenediamine and the like. It is also preferable that these aromatic rings have a structure in which a nitro group is substituted.

Examples of the black paste solvent include amide polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide and N, N-dimethylformamide, lactone polar solvents, dimethyl sulfoxide and the like. Although preferably used, in order to enhance the dispersing effect of carbon black, those containing at least an amide-based polar solvent are preferable, and more preferably an amide-based polar solvent is a solvent containing a main component or an amide-based polar solvent alone. Is preferred. Here, the solvent in which the amide polar solvent is the main component is a mixed solvent composed of n kinds of solvents,
It contains more than (1 / n) × 100% by weight.
For example, in the case of a two-component solvent, the amide polar solvent is 50
It means that the amide polar solvent is contained more than 33% by weight in the case of a three-component solvent.

Further, when a light-shielding agent other than carbon black is also added, in order to enhance the dispersing effect of the light-shielding agent,
Further, it is preferable to include at least a lactone polar solvent. In particular, when rosin resin acid is used as a dispersant,
It works particularly effectively. Lactones refer to aliphatic cyclic esters having 3 to 12 carbon atoms, and specific examples thereof include β-propiolactone, γ-butyrolactone, and γ-
Examples include valerolactone, δ-valerolactone, γ-caprolactone, and ε-caprolactone, with γ-butyrolactone being particularly preferred in view of the solubility of the polyimide precursor. For this reason, it is more preferable to use a mixed solvent of an amide polar solvent and a lactone polar solvent.

Other solvents such as methyl cellosolve, ethyl cellosolve, methyl carbitol, ethyl carbitol, ethyl lactate and the like having a higher evaporation rate and a surface tension of 26 to 33 dynes / cm are used for improving coating properties. It is preferable to add an ether acetate solvent of ethylene glycol or propylene glycol, preferably 1 to 25% by weight, more preferably 5 to 20% by weight of the total solvent. Specifically, propylene glycol methyl ether acetate,
Examples include 3-methyl-3-methoxybutyl acetate, ethylene glycol ethyl ether acetate, and 3-methoxybutyl acetate. Further, it is more preferable to disperse a light-shielding agent such as carbon black in a solution to which these solvents are added, since heat generation during dispersion is reduced, gelation hardly occurs, or dispersibility is improved, and it is more preferable. .

As a method of dispersing a light-shielding agent such as carbon black, for example, a method of mixing a light-shielding agent and a dispersant in a resin solution and then dispersing the mixture in a dispersing machine such as a three-roll mill, a sand grinder, and a ball mill. and so on. When a light-shielding agent other than carbon black is used, a method of dispersing each light-shielding agent alone and then mixing them, or a method of separating carbon black and other light-shielding agents, dispersing each, and then blending each other And the like are more preferably used. When using a polyimide precursor as the resin, the reaction between the polyimide precursor during dispersion,
A method of first mixing a light-shielding agent in a solvent, performing pre-dispersion, and then mixing or dispersing the polyimide precursor later in order to prevent the viscosity increase due to the reaction between the light-shielding agent and the polyimide precursor and prevent gelation and the like. Is more preferred. Further, a method of dispersing or mixing carbon black or a light-shielding agent other than carbon black with a solvent suitable for dispersion or a polyimide precursor containing the solvent is more preferable. In order to finely disperse the light-shielding agent, it is preferable to appropriately adjust the dispersion intensity, the dispersion time, and the like.

The rheological properties of the black paste include:
The yield value according to Casson's flow equation is preferably 0.1 Pa or less, more preferably 0.01 Pa
Or less, more preferably 0.001 Pa or less. If the dispersion stability of the light-shielding agent is poor, the yield value becomes higher than this, and the light-shielding agent is aggregated, and the light-shielding properties of the black matrix are undesirably reduced. Since the black paste of the present invention uses a predetermined carbon black, a low yield value is obtained. S = shear stress, D = shear rate, τ0 = yield value, μ0 = Casson viscosity,
Flow equation is expressed by Equation 1, the yield value is calculated by the square of the intercept of the S ^1/2 axis in the graph of S ^1/2 for D ^1/2.

[0058]

(Equation 1)

The viscosity is appropriately adjusted according to the coating method, but is preferably 5 to 1000 cP, more preferably 8 cP.
It is 150 cP, More preferably, it is 10-100 cP.

Various additives can be added to the black paste for the purpose of improving the dispersibility of the light-shielding agent. In addition, various additives, surfactants, and the like can be added for the purpose of improving coating properties and leveling properties.

Next, a color filter for a liquid crystal display element in which a resin black matrix, pixels, and a protective film are laminated in this order on a light transmitting substrate will be described as an example. First, a black paste is applied on a light transmitting substrate.
The light transmissive substrate is not particularly limited,
Inorganic glasses such as quartz glass, borosilicate glass, soda lime glass having a silica coating on the surface, and organic plastic films or sheets are preferably used. The coating method is, besides dip coating and roll coater,
Rotary coating methods such as wheyers and spinners are preferably used. Thereafter, drying and semi-curing are performed using a hot air oven, a hot plate, or the like. The semi-curing conditions are slightly different depending on the kind and the amount of the polyimide precursor used, but it is general that heating is usually performed at 100 to 180 ° C. for 1 to 60 minutes. If a non-photosensitive polyimide precursor is used, then a photoresist is applied, pre-baked, and exposed using an optical mask. Thereafter, using a developing solution, development of the resist and patterning of the black matrix are successively performed by dip, shower, paddle method or the like. After this,
The resist is stripped by a dip, shower, paddle method or the like using a stripper. Finally, to imidize, 200-
Heat at 400 ° C. for 1-60 minutes and cure. Note that an opening of about 20 to 200 μm is usually provided between the black matrices, and pixels are formed in this space in a later step.

Next, pixels of a plurality of colors are formed in the openings of the black matrix. Usually, the color of each pixel is
The colors are red, blue and green, and are colored by a coloring agent. As a coloring agent used for a pixel, an organic pigment, an inorganic pigment, a dye, or the like can be preferably used. As organic pigments, phthalocyanine-based, azilake-based, condensed azo-based, quinacridone-based, anthraquinone-based, perylene-based,
Perinones and the like are preferably used. The resin used for the pixel may be a photosensitive or non-photosensitive resin such as an epoxy resin, an acrylic resin, a polyimide resin, a urethane resin, a polyester resin, a polyvinyl resin, and a dyeable animal protein resin such as gelatin. It is preferable to disperse or dissolve a coloring agent in these resins to perform coloring.

First, a resin paste containing a coloring agent is applied. In addition to the dip coating and the roll coater, a rotary coating method such as a wicker or a spinner is suitably used. After this,
By drying with hot air, a hot plate, or the like, a first-colored layer is formed over the entire surface of the black matrix. Since the color filter usually includes pixels of a plurality of colors, unnecessary portions are removed by photolithography to form a desired first color pixel pattern. The pixel film thickness is about 0.5 to 3 μm. This is repeated for pixels of the required color to form pixels of multiple colors,
Manufacture color filters.

Thereafter, a protective film is laminated as required.
Examples of the protective film include an acrylic resin, an epoxy resin, a silicone resin, and a polyimide resin, and are not particularly limited.

In addition, after a patterned pixel is formed on a light-transmitting substrate in advance, a photosensitive black paste is applied, and exposure is performed from the light-transmitting substrate side.
There is a method of forming a black matrix between pixels using pixels as a mask, a so-called back exposure method, and the like.

Finally, if necessary, lamination and patterning of the ITO transparent electrode can be performed by a general method.

The resin black matrix for a liquid crystal display element of the present invention is provided not only on the color filter side of the liquid crystal display element as described above but also on the opposing substrate side.
Also not good. For example, in the case of a TFT-LCD, it is located on the TFT matrix array substrate side.
It may be provided on the IM matrix array substrate side, and in the case of STN-LCD, on the opposing stripe electrode substrate side.

The following method can be used to manufacture a liquid crystal display device equipped with a color filter having a resin black matrix manufactured as described above. First, a liquid crystal alignment film is formed on a color filter, and a rubbing process is performed. Similarly, an alignment film is formed and combined with a counter substrate subjected to a rubbing treatment. Subsequently, a liquid crystal is injected between the substrates to assemble the liquid crystal cell, whereby a color liquid crystal display device having the above color filter inside the liquid crystal cell is obtained.

The liquid crystal display element of the present invention has a lower reflectance than the conventional liquid crystal display element having a black matrix, and is mainly due to its achromatic color. The display contrast does not decrease even in places (2) Red, green, and blue coloring are seen vividly (3) Black appears black (4) Background reflection is small (5) Excellent reflection color Shows display characteristics.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

[0071]

EXAMPLES Preparation of Polyimide Precursor Solution 147 g of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride was charged together with 775 g of N-methyl-2-pyrrolidone, and 4,4'-diaminodiphenyl ether 95.10
g and bis (3-aminopropyl) tetramethyldisiloxane were added and reacted at 60 ° C. for 3 hours.
A polyimide precursor solution having a viscosity of 600 poise (25 ° C.) was obtained. The average degree of polymerization was about 27, and both terminals had amine groups. This was applied on a non-alkali glass (“OA-2”, manufactured by NEC Corporation) substrate using a spinner to a finished film thickness of 2 μm, dried with hot air at 80 ° C. for 10 minutes, and then dried at 120 ° C. for 20 minutes. 30 minutes semi-cure, 300 ° C
Cure for a minute. The original stimulus Y of this polyimide film was 95.

Example 1 A carbon black mill base and a blue pigment mill base having the following compositions were mixed at 7000 rpm using a homogenizer at 7000 rpm.
After dispersing for 0 minute, the whole amount was mixed, and the glass beads were removed by filtration to prepare a black paste. The viscosity of the black paste is 32 cP and the yield value is 1.0 × 1
It was 0 ^-4 Pa . As the light-shielding agent, brown carbon black and a blue pigment as its complementary color pigment were used. (1) Carbon black mill base Carbon black ( [COOH] = 0.004, average primary particle size 26 nm, average secondary particle size 57 nm, furnace black) 4.6 parts Polyimide precursor solution 23.0 parts N-methyl Pyrrolidone 61.4 parts Glass beads 90.0 parts (2) Blue pigment Millbase Pigment Blue 15 2.2 parts Polyimide precursor solution 23.0 parts Abieticacid 0.2 parts γ-butyrolactone 63.6 parts Glass beads 90.0 Alkali-free glass (NEC Glass Co., Ltd., "OA-
2 ″) Coating on a substrate with a spinner, drying with hot air at 80 ° C. for 10 minutes, and semi-curing at 120 ° C. for 20 minutes.
Positive resist (Shipley “Microposit” RC100 30cp
) Was applied with a spinner and dried at 80 ° C. for 20 minutes. Exposure was performed through a photomask using an exposure machine PLA-501F manufactured by Canon Inc., and an alkali developer (Shipley “Micr”) was used.
After the development of the positive type resist and the etching of the polyimide precursor were simultaneously performed by “oposit” 351), the positive type resist was peeled off with methylcellosolve acetate, and further cured at 300 ° C. for 30 minutes. A grid-like black matrix having a size of .98 μm and an opening of 240 μm in the vertical direction and 60 μm in the horizontal direction was provided.

Next, as red, green and blue pigments,
Dianthraquinone pigment represented by Index No.65300 Pigment Red 177, Color Index No.74265 Pigment Green 3
Phthalocyanine green pigment shown by 6 Color Inde
x A phthalocyanine blue pigment represented by No. 74160 Pigment Blue 15-4 was prepared. The pigments were mixed and dispersed in a polyimide precursor solution to obtain three kinds of colored pastes of red, green and blue. First, a green paste is applied to the black matrix forming surface side of a light transmitting glass substrate,
The resultant was dried with hot air at 10 ° C. for 10 minutes and semi-cured at 120 ° C. for 20 minutes. After this, a positive resist (Shipley "Microposit" R
C100 30 cp) was applied by a spinner and dried at 80 ° C. for 20 minutes. Exposure is performed using a mask and an alkaline developer (Shipley
After simultaneously developing the positive resist and etching the polyimide precursor with "Microposit" 351), the positive resist is peeled off with methylcellosolve acetate, and green pixels of about 90 μm width and stripes in the vertical direction are drawn in the width direction. The pitch was set to 300 μm. Furthermore, it was cured at 300 ° C. for 30 minutes. The thickness of the pixel layer was 1.5 μm. After washing with water, striped red and blue pixels are similarly
It was formed so that the pixel interval of the color became 10 μm.

Next, a protective film was laminated. As a protective film,
Acetic acid is added to methyltrimethoxysilane and hydrolyzed,
An organosilane condensate was obtained. 3,3 ', 4,4'-Benzophenonetetracarboxylic dianhydride and 3-aminopropyltriethoxysilane were mixed at a molar ratio of 1: 2 in an N-methyl-2-pyrrolidone solvent. To give a condensate having an imide group. A composition in which the organosilane mixture, the condensate having an imide group, and N-methyl-2-pyrrolidone are mixed at a weight ratio of 5: 2: 4 to form red, blue, and green organic colored layers. The resultant was coated and cured to obtain a protective layer of a polyimide-modified silicone polymer having a thickness of 3.0 μm.

The light-shielding property of the black matrix has almost no wavelength dependence, and at a wavelength of 430 to 640 nm,
It was 2.5 to 2.8 (optical density / μm). At this time, the primary stimulus value Y at a wavelength of 400 to 700 nm is 0.1.
It was 40.

Example 2 A carbon black mill base, a purple pigment mill base and a blue pigment mill base having the following compositions were each dispersed using a homogenizer at 7000 rpm for 30 minutes, and then all were mixed, and the glass beads were removed by filtration. Thus, a black paste was prepared. The viscosity of the black paste was 25 cP , and the yield value was 5.0 × 10 ⁻⁵ Pa . As the light shielding agent, brown carbon black and blue pigments and purple pigments were used as complementary color pigments. (1) Carbon black mill base Carbon black ( [OH] = 0.005, average primary particle size 30 nm, average secondary particle size 60 nm, furnace black ) 2.3 parts Polyimide precursor solution 8.0 parts N-methyl Pyrrolidone 61.2 parts Glass beads 71.5 parts (2) Purple pigment mill base Pigment violet 23 0.3 parts Polyimide precursor solution 1.2 parts γ-butyrolactone 2.2 parts Glass beads 3.7 parts (3) Blue pigment Millbase Pigment Blue 15 1.1 parts Abieticacid 0.1 part Polyimide precursor solution 4.9 parts γ-butyrolactone 8.8 parts Glass beads 14.9 parts A color filter was obtained in the same manner as in Example 1 below. However, the thickness of the black matrix was 0.75 μm. The light-shielding property of the black matrix has almost no wavelength dependence, and is 3.1 at a wavelength of 430 to 640 nm.
３3.4 (optical density / μm). At this time, the primary stimulus value Y at a wavelength of 400 to 700 nm was 0.32.

Example 3 A carbon black mill base composition having the following composition
Except for the change, the black paste was applied in the same manner as in Example 2.
Prepared. The viscosity of the black paste is 27 cP ,
The yield value was 7.0 × 10 ⁻⁴ Pa. (1) Carbon black mill base Carbon black ( [SO ₃ H] = 0.005, average primary particle size 25 nm, average secondary particle size 55 nm, furnace black ) 2.3 parts Polyimide precursor solution 8.0 parts N - methylpyrrolidone 61.2 parts glass beads 71.5 parts hereinafter, to obtain a color filter in the same manner as in example 1. B
The light blocking effect of the rack matrix is almost independent of wavelength.
And 3.1 to 3.4 at wavelengths of 430 to 640 nm.
(Optical density / μm). The wavelength at this time is 400 ~
The primary stimulus value Y at 700 nm was 0.32.

Comparative Example 1 A color filter was obtained in the same manner as in Example 1 except that the following carbon black was used.

Carbon black ( [COOH] ≦ 0.0
01, [OH] ≦ 0.001, [SO ₃ H] ≦ 0.00
1, average primary particle size 55 nm, average secondary particle size 110 n
m, furnace black )
The viscosity of the 4.6 part black paste was 60 cP , and the yield value was 0.30 Pa . As compared with Example 1, the light shielding property of the black matrix was 430 to 6
1.9 to 2.3 at 40 nm (optical density / μm)
, The light-shielding property was reduced , and the test was rejected. At this time, the primary stimulus value Y at a wavelength of 400 to 700 nm was 0.80 .

Comparative Example 2 Using a homogenizer, a carbon black mill base having the following composition was dispersed at 7000 rpm for 30 minutes, all the components were mixed, and the glass beads were removed by filtration to prepare a black paste. The viscosity of the black paste is
It was 55 cP and the yield value was 0.2 Pa. As a light shielding agent, only brown carbon black was used. (1) Carbon black mill base Carbon black ( [COOH] ≦ 0.001, [OH] ≦ 0.001, [SO ₃ H] ≦ 0.001, average primary particle size 55 nm, average secondary particle size 110 nm, fur Nest Black ) 4.6 parts Polyimide precursor solution 57.0 parts N-methylpyrrolidone 120.0 parts Glass beads 180.0 parts A color filter was obtained in the same manner as in Example 1. However,
The thickness of the black matrix was 1.4 μm. In addition, the light-shielding property of the black matrix was strongly wavelength-dependent, and the light-shielding property was reduced on the long wavelength side. The light shielding property is 43
At 0 to 640 nm, 1.5 to 2.2 (optical density /
μm). Wavelength 400-7 at this time
The primary stimulus value Y at 00 nm was 0.3 .

Table 1 shows the carboxyl group concentration [COOH] on the surface of the carbon black used in each of Examples and Comparative Examples,
The hydroxyl group concentration [OH] on the surface and the sulfone group concentration [S on the surface
O ₃ H], average primary particle size, average secondary particle size, presence / absence of complementary color pigment, viscosity of black paste obtained, yield value, light-shielding property per film thickness of black matrix, wavelength dependency of light-shielding property Is summarized.

Table 2 summarizes the chromaticity coordinates of the transmitted light of each resin black matrix in the C light source.

Table 3 summarizes the chromaticity coordinates of the transmitted light of each resin black matrix during backlight irradiation.

Table 4 summarizes the light transmittance of each resin black matrix at each main wavelength of the backlight.

Table 5 summarizes the chromaticity coordinates of the transmitted light of each black paste in the C light source.

[0086]

[Table 1]

[0087]

[Table 2]

[0088]

[Table 3]

[0089]

[Table 4]

[0090]

[Table 5]

A liquid crystal display device (TFT (thin film transistor) type) equipped with a color filter having a resin black matrix manufactured as described above, another chrome black matrix, a liquid crystal display device having a two-layer chrome black matrix, and a comparison. The contrast ratio of a CRT (color cathode ray tube) is generally defined by visibility: white luminance / black luminance, but if there is reflected light, it is represented by (white luminance + reflection) / (black luminance + reflection). ) Was compared (Fig. 1). The luminance was measured with Topcon Black Matrix-5 or Black Matrix-7. When the room illuminance was high, the result was obtained that the contrast ratio of the liquid crystal display device equipped with the color filter having the resin black matrix did not decrease much and the display was easy to see even in a bright place. The characteristics of the liquid crystal display device equipped with a resin black matrix color filter that can be perceived sensibly are (1) Vivid red, green and blue coloring (2) Black is black (3) Background reflection is small (4) There was no color of reflection.

[0092] Further, when a monitor survey of 100 persons was conducted, data statistically supporting the characteristics of the liquid crystal display device equipped with a resin black matrix color filter were obtained.

The color filter of the present invention can obtain a color filter for a liquid crystal display element having a black matrix having excellent color characteristics by dispersing a specific light-shielding agent in a resin as described above. Thus, a liquid crystal display device excellent in the above was obtained.

[0094]

The resin black matrix of the present invention comprises:
Dispersibility can be improved by dispersing specific carbon black as a light-shielding agent in the resin as described above, and a black matrix having high light-shielding properties, excellent pattern workability, and no film peeling can be obtained. Thus, a liquid crystal display element having excellent display quality can be obtained. Also,
By applying a black paste obtained by dispersing a specific carbon black in a resin solution,
An excellent resin black matrix is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram comparing the dependence of contrast ratio on indoor illuminance.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-67421 (JP, A) JP-A-6-35188 (JP, A) JP-A-4-63870 (JP, A) JP-A 47-67 34819 (JP, A) JP-A-50-28531 (JP, A) JP-A-50-141612 (JP, A) JP-A-50-142626 (JP, A) JP-A-55-89361 (JP, A) JP-A-2-239204 (JP, A) JP-B 46-18368 (JP, B1) JP-B 52-2874 (JP, B1) WO 95/35525 (WO, A1) (58) Int.Cl. ⁷ , DB name) G02B 5/00-5/136 G02B 5/20-5/28 G02F 1/1335 C08K 3/00-13/08 C08L 1/00-101/14 C09C 1/00- 3/12 C09D 1/00-201/10

Claims (19)

(57) [Claims] 1. A resin black matrix in which a light-shielding agent is dispersed in a non-photosensitive polyimide resin, wherein carbon black satisfying at least one of the following (A) to ( C ) is used as the light-shielding agent: Resin matrix . (A ) The carboxyl group concentration [COOH] on the surface satisfies 0.001 <[COOH] in molar ratio per total carbon atoms. ( B ) The hydroxyl group concentration [OH] on the surface satisfies 0.001 <[OH] in a molar ratio per total carbon atoms. ( C ) The sulfone group concentration [SO ₃ H] on the surface satisfies 0.001 <[SO ₃ H] in molar ratio per total carbon atoms. 2. The resin black matrix according to claim 1, wherein the light-shielding agent has an average primary particle size of 5 to 40 nm. 3. The resin black matrix according to claim 1, wherein the light-shielding agent has an average secondary particle size of 5 to 100 nm. 4. The resin black matrix according to claim 1, wherein the blackening agent comprises carbon black and a pigment complementary to the carbon black. 5. A pigment complementary to carbon black,
The resin black matrix according to claim 4, which is a blue and / or purple pigment. 6. The resin black matrix according to claim 1, wherein the proportion of carbon black contained in the light-shielding agent is 50% by weight or more. 7. A black paste obtained by dispersing a light-shielding agent in a non-photosensitive polyimide precursor solution, wherein carbon black satisfying at least one of the following (A) to ( C ) is used as the light-shielding agent: Characteristic black paste . (A ) The carboxyl group concentration [COOH] on the surface satisfies 0.001 <[COOH] in molar ratio per total carbon atoms. ( B ) The hydroxyl group concentration [OH] on the surface satisfies 0.001 <[OH] in a molar ratio per total carbon atoms. ( C ) The sulfone group concentration [SO ₃ H] on the surface satisfies 0.001 <[SO ₃ H] in molar ratio per total carbon atoms. 8. The black paste according to claim 7, wherein the light-shielding agent has an average primary particle size of 5 to 40 nm. 9. The black paste according to claim 7, wherein the light-shielding agent has an average secondary particle size of 5 to 100 nm. 10. The black paste according to claim 7, comprising carbon black and a pigment complementary to said carbon black as a light-shielding agent. 11. The black paste according to claim 10, wherein the pigment complementary to carbon black is a blue and / or purple pigment. 12. The black paste according to claim 7, wherein the proportion of carbon black contained in the light-shielding agent is 50% by weight or more. 13. The black paste according to claim 7, wherein an amide polar solvent selected from N-methyl-2-pyrrolidone, dimethylformamide and dimethylacetamide is used as a main component of the solvent. 14. The black paste according to claim 7, comprising at least a lactone-based solvent. 15. The black paste according to claim 7, which contains at least an ethylene glycol-based or propylene glycol-based ether acetate solvent having a surface tension of 26 to 33 dynes / cm. 16. The black paste according to claim 7, wherein a yield value according to Casson's flow equation is 0.1 Pa or less. 17. The black paste according to claim 7, having a viscosity of 5 to 1000 cP. 18. A color filter comprising the resin black matrix according to claim 1. 19. A liquid crystal display device comprising the color filter according to claim 18.