JP2000053915A - Black coating composition, resin black matrix using the same, color filter for liquid crystal display, substrate for liquid crystal display, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a black-coating composition that can prepare a resin black matrix having excellent shading effect and electric insulation (high resistance) by using a combination of a carbon body and a coloring pigment. SOLUTION: The objective composition comprises at least (A) a binding resin (suitably a polyimide resin), (B) a carbon body (suitably at least partially comprising powdery graphite) and (C) a coloring pigment and has an electric resistance of >=109 Ω. In a preferred embodiment, the weight ratio of the component B/the component C is adjusted in the range from 80/20 to 40/60. The component B is pref. a powdery carbon black with a primary particle size of <=40 nm, while the component C has a primary particle size of <=40 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a black coating film composition used for a resin black matrix of a liquid crystal display device, a resin black matrix using the same, a color filter for a liquid crystal display, a substrate for a liquid crystal display, and a liquid crystal display. It concerns the device.

[0002]

2. Description of the Related Art A liquid crystal display device performs display of images and characters and information processing by using electro-optical response of a liquid crystal. Specifically, a personal computer, a word processor, a navigation system, a liquid crystal television, It is used for display screens such as video, liquid crystal projectors, liquid crystal spatial modulation devices, and the like.

In a liquid crystal display, a black matrix is required as a light-shielding film between pixels or in a portion where light transmission is desired, such as a driving circuit portion. As the material of the light-shielding film, a material having a large extinction coefficient such as chromium, nickel, and aluminum is used. As a method of forming a light-shielding film using these metals, a vapor deposition method, a sputtering method, and a vacuum film-forming method are generally used, and the light-shielding film is patterned by a photolithography method. As a typical example, a photoresist is applied to a metal thin film formed by the above method, dried, then irradiated with ultraviolet rays through a photomask to form a resist pattern, and then manufactured through steps of etching and resist peeling. Is done. However, in this method, the production cost is increased due to the complexity of the process, and therefore the cost of the color filter itself is increased.
Furthermore, when a substrate for a liquid crystal display device having a black matrix formed of this metal thin film is mounted, the reflectance of the surface of the metal thin film is high. The problem of lowering occurs.

On the other hand, as a light-shielding material other than metal, crystalline carbon powder, that is, graphite powder, is known as having a high light-shielding property, but has a problem that its electric resistivity is as low as about ^10-4 Ω · cm. is there. Therefore, a method of using carbon black as a carbon body having a higher electrical resistivity than graphite powder is described in Japanese Patent Application Laid-Open No. 9-15403 and the like, which discloses a composition comprising a resin and carbon black. A method of forming a black matrix by forming a black paste by dispersing in an appropriate solvent and applying the black paste to a substrate is disclosed. Also in this case, the patterning of the light-shielding film is performed by a method similar to the above-described photolithography. The black matrix is formed by a black paste coating method, and since carbon black having a relatively high electrical resistivity is used as a light shielding material, low cost can be achieved in the process, and the reflectance is higher than that of a metal light shielding material. Features such as reduction. However, since carbon black has a smaller extinction coefficient with respect to visible light than metal and graphite, the optical density (OD value) of the black coating film using this as a light shielding agent is low.
In order to maintain a high OD value, it is necessary to increase the thickness of the black coating film. However, when the black matrix has a large thickness, when used as a liquid crystal color filter, the unevenness of the surface becomes large, which causes disturbance of the liquid crystal display. In addition, a black light-shielding film having a high electric resistivity can be obtained by mixing color pigments such as red (R), green (G), blue (B), and purple (V). Is low.

The structure of a conventional liquid crystal display device basically includes an electrode substrate having a black matrix, a counter electrode substrate having a transparent conductive film formed on a transparent substrate, and a liquid crystal sandwiched between the two substrates. It consists of layers. In particular,
In order to perform color display using these liquid crystal display devices, a method is employed in which a color filter composed of pixels having color selectivity is formed on a substrate in addition to a black matrix. The liquid crystal layer has a predetermined structure in advance, the structure is controlled by an electric field applied between the two substrates, and the amount of light transmitted through the liquid crystal layer is adjusted in accordance with the change in the structure, thereby displaying the image. Is performed.

As a predetermined liquid crystal structure, currently, Twisted Ne
The most common is a liquid crystal structure called a matics (TN) structure, that is, a method of forming a structure twisted in the thickness direction. However, the liquid crystal display of the TN mode has a problem that the viewing angle is narrow, and the viewing angle is currently widened using a viewing angle widening film or the like.

For this reason, a method called an in-plane switching (IPS) method as disclosed in JP-A-7-159786 has recently been receiving attention as a liquid crystal display method capable of obtaining a wide viewing angle. In this method, liquid crystal molecules are aligned in parallel with the electrode substrate, and a comb-shaped electrode is formed only on one of the substrates so as to be opposed, and an electric field is applied between the opposed electrodes, that is, an electric field is applied in the in-plane direction of the liquid crystal layer. The amount of transmitted light is adjusted by rotating the liquid crystal within the layer plane.

However, in the IPS system in which an electric field is applied in the in-plane direction of the liquid crystal layer, if the electric resistance of the black matrix of the opposing substrate is low, the electric field is not normally applied, and as a result, the liquid crystal alignment is disturbed and display unevenness occurs. This causes the problem of causing

A black matrix using the above-described carbon black as a shielding agent has insufficient light-shielding properties and electric resistance in the IPS system. Although it is possible to increase the resistance by reducing the composition ratio of carbon black, there remains a problem that high light-shielding properties cannot be maintained.

As one of the shielding agents having high electric resistance, titanium oxide (TixOy, generally, x / y is 1 /
(Larger than 2) (for example, JP-A-64-26820). In addition, as a more excellent light shielding properties,
Titanium oxynitride powder (TiNxOy, where 0 ≦ x <
A high resistance shielding film using 1.4, 0.1 <y <1.8) is known (Japanese Patent Application Laid-Open No. 1-141963).

However, any of the above-mentioned titanium compounds has a problem that the coating liquid composed of a mixture with a resin is inferior in storage stability and the compound is easily deposited after standing.

[0012]

SUMMARY OF THE INVENTION In view of the above problems, the present invention makes it possible to produce a resin black matrix having excellent light-shielding properties and electrical insulation (high resistance) by using a carbon body and a coloring pigment together as a light-shielding agent. It is an object of the present invention to provide a black coating composition, a resin black matrix using the same, a liquid crystal display color filter, a liquid crystal display substrate, and a liquid crystal display device.

[0013]

To solve the above problems, the present invention has the following arrangement.

That is, (1) a black coating composition comprising at least a binder resin, a carbon body, and a coloring pigment, and having an electric resistance of 10 ⁹ Ω · cm or more.

In particular, (2) the composition weight ratio of the carbon body to the color pigment is in the range of carbon body / color pigment = 80/20 to 40/60, and (3) the binder resin is a polyimide resin. (4) It is preferable that at least a part of the carbon body is a graphite powder.

Further, the resin black matrix of the present invention is a resin black matrix comprising the above black coating composition.

Further, the color filter for liquid crystal display is a color filter for liquid crystal display using the above resin black matrix, and the liquid crystal display substrate and the liquid crystal display device each use the color filter.

In particular, a uniform display can be obtained even in a liquid crystal display device using an in-plane switching method.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention have conducted intensive studies to obtain a black coating film having a high resistivity and a high OD value as described above, and have found that a carbon material such as graphite powder or carbon black and a coloring pigment are used. It has been found that the above-mentioned performance can be achieved with a coating film having a small thickness. That is, by mixing the carbon body and the coloring pigment, not only the electrical resistivity as the composition average of the respective performances and the OD value are obtained, but when these materials are mixed in a range of a preferable weight composition ratio,
It has been found that a performance higher than the composition average can be obtained by the effect of mixing. The performance above the composition average appears in this way, for example, by embedding a fine colored pigment between particles having a relatively large particle diameter such as graphite powder, without lowering the OD value, and by the colored pigment. This is because the electric resistance can be significantly increased.

The black coating composition of the present invention has an electric resistance of 1
It is necessary that the 0 ⁹ Ω · cm or more. Electric resistance is 10 ⁹ Ω
When it is less than cm, when it is used for forming a resin black matrix of an in-plane switching type liquid crystal display device, an electric field is not normally applied, and the liquid crystal alignment is disturbed, which causes display unevenness.

In the present invention, the electric resistance of the black coating composition is determined based on the black coating film of a resin black matrix obtained by patterning the film coated and baked on a glass substrate using a black paste. Volume electric resistance (ρ) means volume electric resistance (ρ) of the black coating film is determined by a three-terminal method with a guard ring, which is above and below the black coating film (electrode area (S), light-shielding film thickness (d)). A voltage (V) is applied to the electrode surface provided in the above, and the current is obtained from the flowing current (I) using the following equation.

Ρ = (V / I) · (S / d) On the other hand, an optical density OD (optical density) which is an index of light-shielding property.
The ty) value was determined from the following relational expression using a microspectroscope (MCPD2000 manufactured by Otsuka Electronics).

OD value = log ₁₀ (I ₀ / I) where I ₀ is the incident light intensity and I is the transmitted light intensity.

The black coating composition of the present invention contains a carbon body, a color pigment, and an adhesive resin as essential components, and the carbon body means graphite powder or carbon black.

In the present invention, the graphite powder is a carbon powder having high crystallinity, which is referred to as graphite powder, flaky carbon, or having a crystal size Lc determined by X-ray analysis of 30 nm or more. Which is generally referred to as graphite powder. The particle size of the graphite powder is 2 μm or less, more preferably 1.5 μm or less.

The carbon black means fine carbon black such as acetylene black, Ketjen black, furnace black and aniline black. The primary particle size of the carbon black powder is preferably 40 nm or less, more preferably 30 nm or less. The primary particle diameter can be determined by arithmetic mean with an electron microscope.

In the present invention, among the above-mentioned carbon bodies,
It suffices to include at least one type, and it is possible to use two or more types together, but it is preferable to include graphite powder.

The coloring pigments are red (R), green (G),
It means fine particle pigments such as blue (B) and purple (V), and these color pigments are characterized by high volume electrical resistivity.
The primary particle size of the color pigment powder is preferably 40 nm or less, more preferably 30 nm or less.

The weight composition ratio of the carbon body / colored pigment is as follows:
The range of 80/20 to 40/60 is preferable in terms of high resistance and high OD value. When the weight ratio of the carbon body exceeds 80, the electric resistance of the black coating film decreases. On the other hand, when it is less than 40, the OD value sharply decreases.

In the present invention, specific examples of the binder resin include an epoxy resin, an acrylic epoxy resin, an acrylic resin, a siloxane polymer resin, a polyimide resin,
Examples thereof include a silicon-containing polyimide resin, a polyimidesiloxane resin, and a polymaleimide resin, and a polyimide resin such as a polyimide resin, a silicon-containing polyimide resin, a polyimidesiloxane resin, and a polymaleimide resin is preferable. This is because black matrices using these resins are more excellent in flatness, coatability and heat resistance.

In the present invention, the weight composition ratio of (carbon body + colored pigment) / binder resin is preferably in the range of 80/20 to 30/70 in terms of high resistance and high OD value. When the weight ratio of (carbon body + colored pigment) exceeds 80, subsequent pattern processing is difficult. On the other hand, when it is less than 30, the OD value sharply decreases.

A coating liquid (black paste) of a black coating composition produced from a precursor resin of these resins, a carbon body and a coloring pigment has excellent storage stability, and the obtained black matrix has flatness and coatability. Excellent in heat resistance.

A polyimide-based resin precursor such as polyamic acid contained in the black coating composition is applied on a substrate and heat-treated to form a ring-closed imidized by heating.
A polyimide polymer film is formed. Polyamic acid is
Usually, a structural unit represented by the general formula (1) is mainly used.

General formula (1)

Embedded image Here, n in the general formula (1) is 0 or a number of 1 to 4. R ¹ is an acid component residue, and R ¹ is 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 heterocycle, and has 6 to 30 carbon atoms.
Valent groups are preferred. Examples of R ¹ include a phenyl group, a biphenyl group, a terphenyl group, a naphthalene group, a perylene group, a diphenyl ether group, a diphenylsulfone group,
Examples include, but are not limited to, groups derived from diphenylpropane, benzophenone, biphenyltrifluoropropane, cyclobutyl, cyclopentyl, and the like.

R ² represents a divalent organic group having at least two carbon atoms. From the viewpoint of heat resistance, R ² is preferably a divalent group containing a cyclic hydrocarbon, an aromatic ring or an aromatic heterocyclic ring and having 6 to 30 carbon atoms. Examples of R ² include phenyl, biphenyl, terphenyl, naphthalene, perylene, diphenylether, diphenylsulfone, diphenylpropane, benzophenone, biphenyltrifluoropropane, diphenylmethane, cyclohexylmethane, and the like. Derived groups include, but are not limited to.
In the polymer having a structural unit represented by the general formula (1) as a main component, R ¹ and R ² may each be composed of one type, or may be composed of two or more types. It may be united. The black paste of the present invention includes other N-
Organic solvents such as methyl-2-pyrrolidone, γ-butyrolactone, 3-methyl-3-methoxybutyl acetate;
Further, a surfactant or the like can be included for improving film coating properties.

The black coating composition of the present invention is produced by applying the above-mentioned black paste on a glass substrate, and is produced, for example, by the following method. That is, the coating liquid (black paste) of the above-described black coating composition is applied on a glass substrate by a dipping method, a roll coater method, a spinner method, a die coating method, a method using a wire bar, or the like, and thereafter, an oven or hot Heat drying and curing are performed using a plate. The heating condition depends on the resin used,
Although it depends on the solvent and the amount of application, usually at 50 to 200 ° C,
It is preferable to heat for 1 to 100 minutes. This state is called a semi-cured state, and the film in this state is called a semi-cured film. The semi-cured film is further treated at 200 to 400 ° C. for 1 to 3
A cured film is obtained by heating for 00 minutes.

The resin black matrix of the present invention is produced by patterning the above-mentioned black coating composition in a semi-cured state. The coating film coated in the same manner as described above is usually subjected to pattern processing using a method such as photolithography. That is, when the resin is a non-photosensitive resin, a photoresist film is formed thereon, and when the resin is a photosensitive resin, it is exposed as it is or after forming an oxygen barrier film. Develop to form the desired pattern. Further, if necessary, the photoresist or the oxygen barrier film is removed, and then the substrate is heated and cured. The thermosetting conditions differ depending on the resin, but when a polyimide resin is obtained from the precursor, it is generally heated at 200 to 350 ° C. for 1 to 60 minutes.

In particular, the case where a polyimide resin is used as the binder resin will be further described. A polyamic acid film formed by the black coating composition of the present invention using a precursor of a polyimide resin having a structural unit represented by the above general formula (1) as a main component as the polyamic acid is subjected to pattern processing by wet etching. In this case, if the molecular weight of the precursor is too large, there is a problem that the time required for development becomes too long. For this reason, it is usually desirable that the polymerization degree is in the range of 5 to 1,000.

The above-mentioned polyamic acid film is subjected to a chemical treatment or a heat treatment to form a polymer having an imide ring or another cyclic structure (polyimide, polyamideimide), whereby a pigment-dispersed polyimide film can be obtained. A polyimide film can be obtained from an ester or the like.

The resin black matrix thus obtained has an OD of 430 to 640 nm in the visible light range.
Preferably, the value is at least 2.5. It is more preferably at least 3.5, even more preferably at least 4.0. OD
When the value is less than 2.5, the contrast of display at the time of driving the liquid crystal is reduced, and the display quality is significantly reduced. In addition, when light is not sufficiently shielded by the black matrix and light enters a thin film transistor or the like formed in the liquid crystal display device, a malfunction of the thin film transistor may occur.

Furthermore, in the in-plane switching type liquid crystal display element, the electric resistance of the resin black matrix needs to be 10 ⁹ Ω · cm or more for uniform display without unevenness (International Display Wo).
rkshop '97, p167).

The thickness of the resin black matrix is 0.3 μm to 3 μm, more preferably 0.5 μm to 2 μm.
0 μm, more preferably 0.7 to 1.5 μm. In order to reduce the step between the black matrix and the pixel, the thickness of the resin black matrix is preferably 2 μm or less. Also, from the viewpoint of pattern formation and securing of OD value,
It is preferably 0.3 μm or more.

The color filter for a liquid crystal display of the present invention comprises:
For example, as shown in Japanese Patent Publication No. 2-1311, first, a black matrix is formed on a transparent substrate using the above-described black coating composition, and then red (R), green (G), and blue (B) are formed. Is formed, and an overcoat film is formed thereon as necessary.

Specific examples of the material of the pixel include an inorganic film whose film thickness is controlled so as to transmit only arbitrary light, and a colored resin film in which dyeing, dye dispersion or pigment dispersion is performed.

The pigment used for the pixel in the present invention is not particularly limited, but a pigment excellent in light resistance, heat resistance and chemical resistance is desirable. Specific examples of typical pigments are indicated by color index (CI) numbers. Examples of yellow pigments include Pigment Yellow 20, 24, 83, 86, 93, 9
4, 109, 110, 117, 125, 137, 13
8, 139, 147, 148, 153, 154, 16
6, 173 and the like. Pigment oranges 13, 31, 36, 38, 40, 4 are examples of orange pigments.
2, 43, 51, 55, 59, 61, 64, 65 and the like. Examples of red pigments include Pigment Red 9, 97, 122, 123, 144, 149, 166,
168, 177, 190, 192, 215, 216, 2
24 and the like. Examples of violet pigments include Pigment Violet 19, 23, 29, 32, 33, 36,
37, 38 and the like. Examples of blue pigments include Pigment Blue 15 (15: 3, 15: 4, 15: 6, etc.), 21, 22, 60, 64, and the like. Examples of green pigments include Pigment Green 7, 10, 36,
47 and the like. In addition, pigments that have been subjected to surface treatment such as rosin treatment, acidic group treatment, and basic group treatment may be used as necessary. In order to improve the adhesion of the resin black matrix, a pigment whose pigment surface is coated with a resin may be used as necessary.

The resin used as the colored resin film is not particularly limited, and acrylic resin, polyvinyl alcohol, polyamide, polyimide and the like can be used. It is preferable to use a pigment-dispersed resin film for the pixel in terms of simplicity of the manufacturing process, heat resistance, light resistance, and the like. From the viewpoint of ease of pattern formation, it is preferable to use a photosensitive acrylic resin in which a pigment is dispersed. But,
From the viewpoint of heat resistance and chemical resistance, it is preferable to use a polyimide film in which a pigment is dispersed.

In a color filter for liquid crystal display, a black matrix composed of the light shielding film is arranged between pixels.
With the arrangement of the black matrix, the contrast of the liquid crystal display device can be improved, and malfunction of a driving element of the liquid crystal display device due to light can be prevented.

A fixed spacer may be formed on the substrate for a liquid crystal display device of the present invention. The fixed spacer is fixed at a specific position on the substrate for a liquid crystal display device as shown in JP-A-4-318816, and comes into contact with the opposite substrate when the liquid crystal display device is manufactured.
As a result, a certain gap is maintained with the counter substrate. Liquid crystal is injected into this gap. By disposing the fixed spacers, it is possible to omit the step of spraying the spherical spacers and the step of kneading the rod-shaped spacers in the sealant in the manufacturing process of the liquid crystal display device.

The fixed spacer is formed by a method such as photolithography, printing, or electrodeposition. Since the spacer can be easily formed at a designed position, it is preferable to form the spacer by photolithography.

In the present invention, it is more preferable that the color filter is formed by forming an overcoat film after forming a resin black matrix, forming pixels, or arranging fixed spacers on a substrate. .

The thickness of the overcoat after heat curing is as follows:
When applied on a substrate having irregularities, the overcoating agent tends to be thicker at the concave portion (portion lower than the periphery) and thinner at the convex portion (portion higher than the periphery) due to the leveling property of the overcoat agent. In the present invention, the thickness of the overcoat is not particularly limited, but is 0.01 to 5 μm, preferably 0.03 to 5 μm.
It is 4 μm, more preferably 0.04 to 3 μm.

The liquid crystal display of the present invention is a liquid crystal display using the above-described color filter for liquid crystal display, wherein liquid crystal is injected into a gap between the liquid crystal display and a counter substrate. In particular, it is possible to obtain a uniform display even in a liquid crystal display device using in-plane switching elements.

[0053]

EXAMPLES The present invention will be described below more specifically based on examples. However, the present invention is not limited to these examples.

Example 1 In a solvent of γ-butyrolactone (3825 g), pyromellitic dianhydride (149.6 g), benzophenonetetracarboxylic dianhydride (225.5 g), 3,3′-diaminodiphenyl sulfone ( 69.5 g), 4,4 '
-Diaminodiphenyl ether (210.2 g), bis-3- (aminopropyl) tetramethylsiloxane (1
After reacting 7.4 g) at 60 ° C. for 3 hours, maleic anhydride (2.25 g) was added and further reacted at 60 ° C. for 1 hour to obtain a precursor polyamic acid solution (polymer concentration 15% by weight). ) Got.

3. Graphite powder (manufactured by Hitachi Powdered Metals)
16 g, B pigment (Pigment Blue 15) 1.90 g,
0.34 g of V pigment (Pigment Violet 23), the above-mentioned polyamic acid solution 5 having a polymer concentration of 15% by weight
0.6 g, N-methyl-2-pyrrolidone 30.1 g, 3
12.9 g of -methyl-3-methoxybutyl acetate was used together with 100 g of glass beads using a homogenizer,
After a dispersion treatment at 7000 rpm for 30 minutes, the glass beads were removed by filtration to obtain a pigment dispersion having a pigment concentration of 14% by weight. The primary particle size of the graphite powder used was 1 μm.

To 27.5 g of this pigment dispersion, 3.7 g of the above-mentioned 15% by weight polyamic acid solution of polymer and γ-
Butyrolactone 1 g, N-methyl-2-pyrrolidone 6
g, 3-methyl-3-methoxybutyl acetate 1.8
g was added and mixed to prepare a coating liquid (black paste) of a black coating composition.

The weight ratio of the light-shielding agent powder / polyimide resin in the black paste was 40/60, the weight ratio of graphite / colored powder was 65/35, and the weight ratio of B / V was 85/1.
It was 5.

After applying the above black paste on an alkali-free glass substrate, prebaking was performed at 145 ° C. to form a polyimide precursor black colored film. Next, the polyimide precursor black colored film was heated to 290 ° C. and thermally cured to be converted to polyimide to form a resin black matrix. After the black paste used here was stored at −15 ° C. for 30 days, the state of dispersion was examined, but no deposition was observed. The thickness of the obtained light-shielding film for resin black matrix was 1 μm, the OD value was 3.4, and the electric resistance was 2 × 10 ⁹
Ω · cm.

Example 2 0.56 g of graphite powder (manufactured by Hitachi Powdered Metals) and 5.04 of carbon black (manufactured by Colombian Carbon Japan)
g, 2.04 g of B pigment (Pigment Blue 15), 0.36 g of V pigment (Pigment Violet 23), polyamic acid solution 4 of Example 1 having a polymer concentration of 15% by weight
0.0 g, 39.1 g of N-methyl-2-pyrrolidone, 3
12.9 g of -methyl-3-methoxybutyl acetate was used together with 100 g of glass beads using a homogenizer,
After a dispersion treatment at 7000 rpm for 30 minutes, the glass beads were removed by filtration to obtain a pigment dispersion having a pigment concentration of 14% by weight. The primary particle size of the carbon black powder used was 28
nm.

Using this pigment dispersion, a black paste was prepared in the same manner as in Example 1. Black paste light shielding powder /
The weight ratio of the polyimide resin is 50/50, the weight ratio of the carbon body / colored powder is 70/30, and the weight ratio of B / V is 85.
/ 15. The thickness of the obtained light-shielding film for a resin black matrix was 1 μm, the OD value was 3.0, and the electric resistance was 4 × 10 ¹⁰ Ω · cm.

Example 3 4.47 g of graphite powder (manufactured by Hitachi Powdered Metals), 3.35 g of R pigment (Pigment Red 177), 3.35 g of G pigment (Pigment Green 7), and the polymer concentration of Example 1 was 15% by weight. 18.56 g of polyamic acid solution, γ
57.4 g of butyrolactone, 12.9 g of 3-methyl-3-methoxybutyl acetate, 100 g of glass beads
Together with a homogenizer at 7000 rpm for 30 minutes.
After the dispersion treatment for 1 minute, the glass beads were removed by filtration to obtain a pigment dispersion having a pigment concentration of 14% by weight. The primary particle size of the graphite powder used was 1 μm.

Using this pigment dispersion, a black paste was prepared in the same manner as in Example 1. The weight ratio of the light-shielding agent powder / polyimide resin of this black paste was 70/30, the weight ratio of graphite / colored powder was 40/60, and the weight ratio of R / G was 50/50.厚 み The thickness of the obtained light-shielding film for resin black matrix was 1 μm, the OD value was 2.8, and the electric resistance was 3 × 10 ⁹ Ω · cm.

Comparative Example 1 A black paste was prepared in exactly the same manner as in Example 1, except that the weight ratio of graphite to the colored powder in the black paste was changed to 82/18. The thickness of the obtained light-shielding film for resin black matrix was 1 μm, and the OD value was as high as 4.8, but the electric resistance was as low as 7 × 10 ⁶ Ω · cm.

Comparative Example 2 2.13 g of R pigment (Pigment Red 177), 2.13 g of G pigment (Pigment Green 7), 2.13 g of B pigment (Pigment Blue 15), polyamic acid of Example 1 having a polymer concentration of 15% by weight Using a homogenizer together with 100 g of glass beads, 50.6 g of an acid solution, 30.1 g of γ-butyrolactone, and 12.9 g of 3-methyl-3-methoxybutyl acetate were dispersed at 7000 rpm for 30 minutes, and then the glass beads were removed by filtration. A pigment dispersion having a pigment concentration of 14% by weight was obtained.

Using this pigment dispersion, a black paste was prepared in the same manner as in Example 1. The weight ratio of the light-shielding agent powder / polyimide resin of the black paste was 40/60, and R / G /
The weight ratio of B was 33/33/33. The thickness of the obtained light-shielding film for a resin black matrix was 1 μm, and the OD value was as low as 1.5.

Example 4 (Preparation of a color filter) After a polyimide precursor black colored film was formed in the same manner as in Example 1, it was cooled, coated with a positive photoresist, and dried by heating at 90 ° C. A resist film was formed. This was exposed through a photomask using an ultraviolet exposure machine. After the exposure, the film was immersed in an alkaline developer, and the development of the photoresist and the etching of the polyimide precursor black colored film were simultaneously performed to form openings. After the etching, the unnecessary photoresist layer was peeled off with methyl cellosolve acetate. The etched polyimide precursor black colored film was heated to 290 ° C. and thermally cured to be converted to polyimide to form a resin black matrix.

[Preparation of Pixel] In a mixed solvent of γ-butyrolactone and N-methyl-2-pyrrolidone, pyromellitic dianhydride (0.5 molar equivalent) and benzophenonetetracarboxylic dianhydride (0.49 Mole equivalent), 4,4'-diaminodiphenyl ether (0.95 mole equivalent), and bis-3- (aminopropyl) tetramethylsiloxane (0.05 mole equivalent) to give a polyamic acid solution (polymer concentration 20% by weight). ) Got.

200 g of this polyamic acid solution was taken out, and 186 g of γ-butyrolactone and 64 g of butyl cellosolve were added to obtain a polyamic acid solution for a pixel having a polymer concentration of 10% by weight.

4 g of Pigment Red 177 (anthraquinone red), 40 g of γ-butyrolactone and 6 g of butyl cellosolve were dispersed together with 100 g of glass beads at 7000 rpm for 30 minutes using a homogenizer, and the glass beads were removed by filtration. A pigment dispersion was obtained.

To 30 g of the pigment dispersion, 30 g of the above-mentioned polyamic acid solution for pixels having a polymer concentration of 10% by weight was added and mixed to obtain a red paste.

A red paste was applied on the resin black matrix and prebaked to form a polyimide precursor red colored film. Using a photoresist, a red pixel was formed by the same means as described above, and was heated to 290 ° C. and thermally cured.

Pigment Green 7 (phthalocyanine green) (3.6 g), Pigment Yellow 83 (benzidine yellow) 0.4 g, γ-butyrolactone (32 g), and butyl cellosolve (4 g) were dispersed together with glass beads (120 g) at 7000 rpm for 30 minutes using a homogenizer. The beads were removed by filtration and a pigment concentration of 10
% By weight of the pigment dispersion was obtained.

To 32 g of the pigment dispersion, 30 g of the above-mentioned polyamic acid solution for pixels having a polymer concentration of 10% by weight was added and mixed to obtain a green paste.

Green pixels were formed in the same manner as in the case of using the red paste, and were heated to 290 ° C. to perform thermosetting.

Using a homogenizer together with 60 g of the above-mentioned polyamic acid solution for pixels having a polymer concentration of 10% by weight, 2.8 g of Pigment Blue 15 (phthalocyanine blue), 30 g of N-methyl-2-pyrrolidone and 10 g of butyl cellosolve together with 150 g of glass beads, 7000 rp
After 30 minutes of dispersion treatment at m, the glass beads were removed by filtration to obtain a blue paste.

According to the same procedure as described above, a blue pixel was formed and heated to 290 ° C. for thermosetting. Thus, a color filter was produced.

The light-shielding properties of the resin black matrix hardly depend on the wavelength, and the optical density is 430 to 640 nm.
Was 3.3 to 3.8. The thickness of the resin black matrix was 1.1 μm.

(Preparation and Evaluation of Color Liquid Crystal Display Element) A polyimide-based alignment film was provided on the color filter, and rubbing treatment was performed. Similarly, a liquid crystal display element substrate provided with a facing thin film transistor was also provided with a polyimide-based alignment film and subjected to a rubbing treatment. This 2
A sealant was applied to the substrates so as to cover the resin black matrix and bonded. Next, liquid crystal was injected from an injection port provided in the seal portion. After injecting the liquid crystal, the injection port was sealed, and a polarizing plate was attached to the outside of the substrate to produce a liquid crystal display device.

When 100 liquid crystal display devices were manufactured through certain known manufacturing steps based on such a method, a liquid crystal display device having no particular problem could be obtained. When the display quality of these liquid crystal display devices was evaluated, the display quality was good.

[0080]

The black coating composition of the present invention is a black coating composition comprising at least a binder resin, a carbon body and a coloring pigment, and has an electric resistance of 10 ⁹ Ω · cm or more. Black matrix having high performance and electrical resistance can be stably manufactured, and in particular, a uniform display can be obtained even in a liquid crystal display device using in-plane switching elements.

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Claims (12)

[Claims] 1. A black coating composition comprising at least a binder resin, a carbon body and a coloring pigment, wherein the black coating composition has an electric resistance of 10 ⁹
A black coating composition having an Ω · cm or more. 2. The black coating composition according to claim 1, wherein the composition weight ratio of the carbon body and the color pigment is in the range of carbon body / color pigment = 80/20 to 40/60. 3. The black coating composition according to claim 1, wherein the binder resin is a polyimide resin. 4. The black coating composition according to claim 1, wherein at least a part of the carbon body is a graphite powder. 5. A black coating composition comprising at least a binder resin, a carbon body and a coloring pigment, wherein the black coating composition has an electric resistance of 10 ^9.
A resin black matrix comprising a black coating composition having a resistance of Ω · cm or more. 6. The composition weight ratio of the carbon body and the color pigment in the black coating composition is as follows: carbon body / color pigment = 80/20 to 40/6.
The resin black matrix according to claim 5, which is in a range of 0. 7. The resin black matrix according to claim 5, wherein the binder resin in the black coating composition is a polyimide resin. 8. The resin black matrix according to claim 5, wherein at least a part of the carbon body in the black coating composition is a graphite powder. 9. A black coating composition comprising at least a binder resin, a carbon body and a coloring pigment, wherein the black coating composition has an electric resistance of 10 ⁹
A color filter for liquid crystal display constituted by a resin black matrix comprising a black coating composition having a resistance of Ω · cm or more. 10. A black coating composition comprising at least a binder resin, a carbon body and a color pigment, wherein the black coating composition has an electric resistance of 10%.
A liquid crystal display device using a color filter composed of a resin black matrix comprising a black coating composition having a resistance of ⁹ Ω · cm or more. 11. The liquid crystal display device according to claim 10, wherein the liquid crystal display device uses an in-plane switching method. 12. A black coating composition comprising at least a binder resin, a carbon body and a color pigment, wherein the black coating composition has an electric resistance of 10%.
An in-plane switching type liquid crystal display substrate using a color filter composed of a resin black matrix comprising a black coating composition of ⁹ Ω · cm or more.