JPH0892496A - Color paste - Google Patents

Abstract

PURPOSE: To obtain a color paste which gives a coating film with a good flatness and can form a color filter having a low intensity of light scattering due to pigment particles under conditions under which it hardly cracks by using a lactone as the principal solvent and both a pigment and a polyamic acid ester as the constituents. CONSTITUTION: This paste contains a pigment and a polyamic acid ester and is prepared by using a lactone as the principal solvent. When the ester part of the polyamic acid ester contains a photoreactive carbon-carbon unsaturated bond, the incorporation of a photopolymerization initiator and a sensitizer into the paste causes a photocrosslinking reaction in the colored coating film by a desirable dose of light, so that a patterned colored coating film can be formed by dissolving an unexposed area in a developer comprising an organic solvent or an aqueous alkali solution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color paste mainly used in the electronic industry. For more information,
The present invention relates to a color paste containing a lactone as a main solvent, which can be used for forming a color filter of a liquid crystal display device or an image pickup device.

[0002]

2. Description of the Related Art As a color paste capable of forming a color filter having excellent heat resistance and light resistance, a color paste in which a pigment is dispersed in an organic solvent solution of polyamic acid is known (for example, JP-A-60). -18420
No. 2, JP-A-60-184203, JP-A-6
1-180203).

Conventionally, as a solvent for polyamic acid, N
Amide polar organic solvents such as -methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide have been used. However, this amide-based polar organic solvent has poor compatibility with the pigment from the viewpoint of dispersibility, and it is difficult to uniformly and stably disperse the finely pulverized pigment in the polyamic acid solution, and an aggregate structure of the pigment is formed. It Therefore, the flatness of the coating film is impaired. Further, the light scattering intensity due to the pigment particles is increased, and the contrast of the pixel is lowered in the TN type liquid crystal display element.

The production of a color filter using a color paste in which a pigment is dispersed in an organic solvent solution of polyamic acid is disclosed, for example, in JP-A-60-247603 and JP-A-61-77804. Then, the following steps are performed. First, a color paste (for example, green) is applied on a substrate and then dried to form a polyimide precursor colored film. A positive photoresist is applied on the polyimide precursor colored coating to form a photoresist coating. A mask is placed on the photoresist film, and ultraviolet rays are irradiated using an exposure device. After exposure,
The photoresist coating and the polyimide precursor colored coating are simultaneously etched with a positive photoresist alkaline developer. After etching, the photoresist film that is no longer needed is removed. After that, the polyimide precursor is converted into polyimide by heat treatment. In this way, after forming a pattern of a one-color polyimide coloring film on a substrate, a color paste of another color (for example, red) is applied thereon, and the same steps are followed to obtain two-color polyimide coloring. A pattern of coating is formed on the substrate. When this is repeated once again, a pattern of three colored polyimide coatings of red, blue and green is obtained.

In this step, a color paste containing an organic solvent is applied onto the polyimide colored coating film, so that the polyimide is required to have a high solvent resistance. However, a polyimide having excellent transparency in a short wavelength region generally has poor solvent resistance. Amide-type polar organic solvent has a very strong dissolving power, and when a color paste in which a pigment is dispersed in an amide-type polar organic solvent solution of polyamic acid is applied onto these highly transparent polyimide films, the surface of the polyimide film becomes rough. However, problems such as cracks occur, and it is difficult to form a multicolor color filter.

[0006]

The present invention was devised in view of the above-mentioned drawbacks of the prior art. The object of the present invention is that the coating film has good flatness and the light scattering intensity by the pigment particles is small. It is an object of the present invention to provide a color paste which can form a color filter under conditions in which cracks are unlikely to occur.

[0007]

The object of the present invention is as follows.
This is achieved by a color paste containing a pigment and a polyamic acid ester and using lactones as a main solvent.

The lactone has a better compatibility with the pigment from the viewpoint of dispersibility than the amide polar organic solvent, and the finely pulverized pigment can be uniformly and stably dispersed in the polyimide precursor solution. In addition, lactones have weaker dissolving power than amide-based polar organic solvents. Therefore, when a color paste containing a lactone as a main solvent is applied onto the polyimide colored coating, it is unlikely that cracks will occur in the polyimide colored coating. However, since the dissolving power is weak, it is difficult to dissolve the polyamic acid that is the polyimide precursor. Therefore, in order to increase the solubility in lactones as in the present invention, it is important to use, as the polyimide precursor, a polyamic acid ester in which a part or all of the carboxyl groups of the polyamic acid are esterified.

The lactones preferably used in the present invention are aliphatic cyclic esters having 3 to 12 carbon atoms. Specific examples include β-propiolactone, γ
-Butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone, and the like, but are not limited thereto. In particular, γ-butyrolactone is preferable from the viewpoint of solubility of polyamic acid ester. In the present invention, lactones are used as the main solvent, but other organic solvents can be used as the auxiliary solvent. As the auxiliary solvent, in addition to the amide-based polar organic solvent, alcohols such as ethanol, butanol, and ethylene glycol, cellosolves such as methyl cellosolve and ethyl cellosolve, carbitols such as methyl carbitol, and ethyl carbitol, methyl. -3-
Examples thereof include aliphatic esters such as methoxypropionate and 3-methyl-3-methoxybutylacetate, and aromatic hydrocarbons such as toluene and xylene. In the present invention, the organic solvent other than the lactones may be used alone or in combination of two or more, without being limited thereto. In addition,
It is desirable that the amount of the sub-solvent is 50% by weight or less, preferably 40% by weight or less, and more preferably 30% by weight or less based on the total amount of the solvent. If the amount of the sub-solvent is too large, there arise problems that the dispersed state of the pigment becomes poor and the polyamic acid ester does not dissolve.

Examples of the polyamic acid ester used in the present invention include those represented by the following general formula (1).

[0011]

[Chemical 1] Here, R ₁ is a tetravalent organic group having 2 to 22 carbon atoms, R ₂ is a divalent organic group having 1 to 22 carbon atoms, R ₃ is hydrogen or a monovalent organic group having 1 to 10 carbon atoms, n Means an integer of 1 or more. The higher the molecular weight, the better the mechanical properties of the polyimide film. Therefore, it is desired that the polyamic acid ester, which is the polyimide precursor, also has a large molecular weight. On the other hand, when the polyimide precursor film is subjected to pattern processing by wet etching, if the molecular weight of the polyamic acid ester is too large, there is a problem that the time required for development becomes too long. Therefore, the preferable range of n is 2-1.
000, more preferably 4 to 400, still more preferably 6 to 100. In addition, since the molecular weight of polyamic acid ester generally varies, the preferable range of n here is 50 mol% or more, preferably 70 mol% or more, and more preferably of all polyamic acid ester within this range. It means that 90 mol% or more is contained.

In the present invention, R ₃ is not all hydrogen. Ratio in which R ₃ is an organic group (esterification ratio)
Is preferably 5 to 100%, more preferably 10 to 9
It is 0%, more preferably 20 to 80%. If the esterification rate is too low, the solubility in lactones decreases. On the other hand, when the esterification rate is high, it is necessary to use an organic solvent as a developing solution when patterning the polyimide precursor film by wet etching. If the esterification rate is low to some extent, wet etching can be performed with an alkaline aqueous solution.

When R ₃ contains a photoreactive carbon-carbon unsaturated bond, the polyimide precursor film can be directly patterned by photolithography without using a photoresist.

One of the methods for producing a polyamic acid ester is as follows. This is a method of obtaining a polyamic acid ester by esterifying tetracarboxylic dianhydride with an organic substance having an alcoholic hydroxyl group to form a tetracarboxylic acid diester, which is then converted to an acid chloride and then reacted with a diamine. In this case, if the end of the polyamic acid ester molecule is amine, the esterification rate of the polyamic acid ester can be adjusted by reacting it with tetracarboxylic dianhydride and diamine.

There is also a method of obtaining a polyamic acid ester by esterifying a tetracarboxylic dianhydride with an organic substance having an alcoholic hydroxyl group to form a tetracarboxylic acid diester, which is reacted with a carbodiimide and then reacted with a diamine. .

Furthermore, a polyamic acid ester can also be obtained by subjecting a carboxyl group of a polyamic acid obtained by reacting a tetracarboxylic dianhydride and a diamine to an organic substance having a glycidyl group or an isocyanate group. be able to.

The present invention is applicable not only to the above-mentioned method but also to polyamic acid ester obtained by any manufacturing method.

The tetracarboxylic dianhydride that can be used in the present invention is represented by the general formula (2)

[Chemical 2] (R ₁ in the formula represents the tetravalent organic group having 2 to 22 carbon atoms). In the present invention, as the tetracarboxylic acid dianhydride, for example, an aliphatic type or an alicyclic type can be used, and specific examples thereof include 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride. Anhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,3,5-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-bicyclohexenetetracarboxylic acid Dianhydride, 1,2,4,5-
Cyclohexane tetracarboxylic dianhydride, 1,3,3
a, 4,5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2
-C] Furan-1,3-dione and the like. Further, when an aromatic type is used, a polyimide precursor composition that can be converted into a polyimide having good heat resistance can be obtained, and specific examples thereof include 3,3 ′, 4,4′-benzophenone. Tetracarboxylic dianhydride, pyromellitic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride, 4 , 4'-oxydiphthalic anhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,3 ", 4 4 "-paraterphenyltetracarboxylic dianhydride, 3,3", 4,4 "
-Metaterphenyl tetracarboxylic acid dianhydride. Further, by using a fluorine-based one, it is possible to obtain a polyimide precursor composition which can be converted into a polyimide having good transparency in a short wavelength region, and as a specific example thereof,
4,4 '-(hexafluoroisopropylidene) diphthalic anhydride and the like can be mentioned. The present invention is not limited to these, and one or more tetracarboxylic dianhydrides may be used.

The diamine is represented by the general formula (3) H ₂ N—R ₂ —NH ₂ (3) (wherein R ₂ represents the divalent organic group having 1 to 22 carbon atoms). The ones shown are: In the present invention, for example, an aliphatic or alicyclic diamine can be used as the diamine, and specific examples thereof include ethylenediamine, 1,3-diaminocyclohexane, and 1,4.
-Diaminocyclohexane, 4,4'-diamino-3,
3'-Dimethyldicyclohexylmethane, 4,4'-diamino-3,3'-dimethyldicyclohexyl and the like can be mentioned. Further, when an aromatic type is used, a polyimide precursor composition which can be converted into a polyimide having good heat resistance can be obtained, and as a specific example thereof, 4,4′-
Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-
Diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 2,5-diaminotoluene, 2,6- Diaminotoluene, benzidine, 3,
3'-dimethylbenzidine, 3,3'-dimethoxybenzidine, o-tolidine, 4,4 "-diaminoterphenyl, 1,5-diaminonaphthalene, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 4 , 4'-bis (4-aminophenoxy) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane,
Examples thereof include bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] sulfone, and bis [4- (3-aminophenoxy) phenyl] sulfone. Further, when a fluorine-based one is used, a polyimide precursor composition which can be converted into a polyimide having excellent transparency in a short wavelength region can be obtained. As a specific example thereof, 2,2-bis [4 -(4-
Aminophenoxy) phenyl] hexafluoropropane and the like.

Further, the general formula (4)

[Chemical 3] (R ₄ in the formula is a divalent organic group having 1 to 10 carbon atoms, R ₅ ,
R ₆ , R ₇ and R ₈ are monovalent organic groups having 1 to 10 carbon atoms and may be the same or different, and m is 1
It means an integer of -10. By using the siloxane diamine represented by the formula (4), the adhesiveness with the inorganic substrate can be improved. The siloxane diamine is usually used in an amount of 1 to 20 mol% based on all diamines. If the amount of siloxane diamine is too small, the effect of improving the adhesiveness will not be exhibited, and if it is too large, the heat resistance will decrease. Specific examples of the siloxane diamine include bis-3- (aminopropyl) tetramethylsiloxane. The present invention is not limited to these, and one or more diamines may be used.

Examples of the organic substance having an alcoholic hydroxyl group used for esterification in the present invention include methanol, ethanol, and those containing a photoreactive carbon-carbon unsaturated bond, such as hydroxyethyl acrylate and hydroxyethyl. Methacrylate, as an example of an organic substance having a glycidyl group, glycidyl methyl ether, glycidyl ethyl ether, as an example of those containing a photoreactive carbon-carbon unsaturated bond, glycidyl acrylate,
Glycidyl methacrylate, as an example of an organic substance having an isocyanate group, methyl isocyanate, ethyl isocyanate, as an example of those containing a photoreactive carbon-carbon unsaturated bond, is an isocyanate ethyl acrylate, isocyanate ethyl Examples include, but are not limited to, methacrylate.

For the polyamic acid ester, the above-mentioned polymerization reaction may be carried out in a solution, and then the polyamic acid ester may be isolated from the solution and dissolved in a lactone, or the polymerization reaction may be carried out in a lactone. It is also possible to directly obtain a lactone solution of the ester. Alternatively, the polymerization reaction may be carried out in an organic solvent other than the lactone, and then the lactone may be added to make up 50% by weight or more of the total solvent.

The color paste of the present invention comprises a pigment dispersed in the above polyamic acid ester solution. The pigment used in the present invention is not particularly limited, but those having excellent light resistance, heat resistance and chemical resistance are preferable. Specific examples of typical pigments are shown by color index (CI) numbers. Examples of yellow pigments include Pigment Yellow 20, 24, 83, 86, 93, 94, 109, 11
0, 117, 125, 137, 138, 139, 14
7, 148, 153, 154, 166, 173 and the like. Pigment Orange 1 is an example of an orange pigment.
3, 31, 36, 38, 40, 42, 43, 51, 5
5, 59, 61, 64, 65 and the like. Examples of red pigments are Pigment Red 9, 97, 122, 1
23, 144, 149, 166, 168, 177, 18
0, 192, 215, 216, 224 and the like. An example of a purple pigment is Pigment Violet 1.
9, 23, 29, 32, 33, 36, 37, 38 and the like. Pigment Blue 1 as an example of a blue pigment
5 (15: 3, 15: 4, 15: 6, etc.), 21, 2
2, 60, 64 and the like. Pigment green 7, 10, 36, 47 etc. are mentioned as an example of a green pigment. Examples of black pigments include Pigment Black 7. In the present invention, various pigments can be used without being limited thereto. The pigment may be subjected to surface treatment such as rosin treatment, acidic group treatment, and basic treatment, if necessary.

Three of R (red), G (green) and B (blue) of color filters used for liquid crystal display elements
Since the color pixels need to be similar to the chromaticity characteristics of the CRT phosphor, the above pigments may be used in a combination of several colors so as to match the light transmission characteristics of the backlight and the liquid crystal display element. preferable. For example, R (red)
Is red pigment and yellow pigment or orange pigment, G (green)
Is a green pigment and a yellow pigment or an orange pigment, and B (blue) is toned by a combination of a blue pigment and a purple pigment. Further, as the black matrix of the color filter, a black pigment or, if necessary, a mixture of pigments of other colors can be used.

In the color paste of the present invention, the polyamic acid ester and the pigment are usually in a weight ratio of 2: 8 to.
It is used in a mixture of 9: 1, preferably 3: 7 to 8: 2, and more preferably 4: 6 to 7: 3. If the amount of the polyamic acid ester is too small, the adhesion of the colored coating to the substrate becomes poor, and if the amount of the pigment is too small, the degree of coloring becomes a problem.

In the production of the color paste of the present invention, there are a method of mixing a dispersion liquid in which a pigment is previously dispersed in a lactone and a polyamic acid ester solution, and a method of dispersing a pigment in the polyamic acid ester solution. . In either method, the pigment is dispersed in the liquid, but the dispersing method is not particularly limited, and may be a ball mill, sand grinder, or 3
Various methods such as the present roll mill and high-speed impact mill can be used.

In the present invention, the concentration of the polyamic acid ester in the color paste is usually 0.5 to 25% by weight, preferably 1 to 15% by weight. If the polyamic acid ester concentration is too low or too high, it will be difficult to apply it to the substrate by the method described below to obtain a good colored coating.

In the color paste of the present invention, when the ester portion of the polyamic acid ester contains a photoreactive carbon-carbon unsaturated bond, a photopolymerization initiator or a sensitizer is added to obtain a preferable exposure. Depending on the amount, a photocrosslinking reaction is caused in the colored coating film, and the unexposed portion is dissolved in a developing solution containing an organic solvent or an alkaline aqueous solution, whereby a patterned colored coating film can be formed. The addition amount of the photopolymerization initiator and the sensitizer is usually 0.5 to 25% by weight of the polyamic acid ester, preferably 1 to
15% by weight. If the amount is too small, the effect will not be exhibited, and if the amount is too large, the strength and adhesive strength of the colored coating will be reduced. Specific examples of the photopolymerization initiator and the sensitizer include Michler's ketone, benzoin ether, 1,2-benzyl-9,
Examples thereof include 10-anthraquinone and N-phenylglycine, but not limited to these, various photopolymerization initiators and sensitizers can be used.

A surfactant may be added to the color paste of the present invention for the purpose of improving the coating property and the drying property of the colored coating film, or for improving the dispersibility of the pigment. The amount of the surfactant added is usually 0.001-1 of the pigment.
It is 0% by weight, preferably 0.01 to 1% by weight. If the amount added is too small, there is no effect of improving the coatability, the drying property of the colored coating, or the dispersibility of the pigment, and if the amount is too large, the coatability is adversely affected or the pigment aggregates. Specific examples of the surfactant include ammonium lauryl sulfate,
Anion surfactants such as polyoxyethylene alkyl ether triethanolamine sulfate, cationic surfactants such as stearylamine acetate, lauryl trimethyl ammonium chloride, amphoteric interfaces such as lauryl dimethyl amine oxide, lauryl carboxymethyl hydroxyethyl imidazolium betaine Examples thereof include nonionic surfactants such as activators, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and sorbitan monostearate. In the present invention,
The surfactant is not limited to these, and one or more surfactants can be used. The addition of the surfactant can be carried out during the pigment dispersion process or at any time before or after the process. However, care must be taken because the dispersibility of the pigment may change depending on the time of addition.

Further, a colloidal substance of inorganic fine particles may be added to the color paste of the present invention in order to improve the hardness of the colored film. Specific examples of the colloidal substance of inorganic fine particles include silica sol, titania sol, zirconia sol, etc., but are not particularly limited thereto. When the colloidal inorganic fine particles are added, the addition amount is preferably 1 to 50% by weight of the polyamic acid.
-30% by weight is more preferred. If the added amount is too large, the colored coating becomes brittle, and if the added amount is too small, the effect of improving the hardness of the colored coating is not exhibited.

The method for applying the color paste of the present invention onto a substrate includes a spin coater, a bar coater, a blade coater, a roll coater, a die coater, a screen printing method, and the like. Various methods such as a dipping method and a method of spraying a paste on the substrate can be used. As the substrate, a transparent substrate such as soda glass, non-alkali glass, borosilicate glass, or quartz glass, or a semiconductor substrate such as silicon or gallium-arsenide is usually used, but is not particularly limited thereto. When applying the color paste on the substrate, treating the substrate surface with an adhesion aid such as a silane coupling agent, an aluminum chelating agent, or a titanium chelating agent may improve the adhesive force between the colored film and the substrate. You can

The color paste of the present invention is used for a color filter of a liquid crystal display or an image pickup device, a light-shielding film of an optical element, a coating film of an optical fiber, and the like. For example, an optical fiber coated with a colored coating using a color paste can be used as an optical sensor under high temperature.

Next, an example of the method of using the color filter for liquid crystal display, which is a typical application of the color paste of the present invention, will be described.

After the color paste is applied on the transparent substrate by the method as described above, the polyimide precursor colored film is formed by air drying, heat drying, vacuum drying or the like. For heat drying, use an oven, hot plate, etc.
It is preferably carried out in the range of 0 to 180 ° C. for 1 minute to 3 hours.
Then, it is converted into a polyimide colored film by heat treatment. The heat treatment is usually performed in air, in a nitrogen atmosphere, or in vacuum at a temperature of 200 to 450 ° C., preferably 250 to 350 ° C., for 0.1 to 5 hours, continuously or stepwise. Done. Next, a pattern is formed on the thus-obtained polyimide colored film by ordinary wet etching. First, a negative photoresist is applied on the polyimide colored coating to form a photoresist coating. Subsequently, a mask is placed on the photoresist film, and ultraviolet rays are irradiated using an exposure device. After the exposure, the photoresist film is etched with a negative photoresist developing solution. Then, the polyimide colored film is etched using hydrazine. After etching, the photoresist film that is no longer needed is removed. When the esterification rate of the polyamic acid ester in the color paste is 10 to 90%, the following steps can be taken. After applying the color paste on the transparent substrate,
A polyimide precursor colored film is formed by air drying, heat drying, vacuum drying, or the like. A positive photoresist is applied on the polyimide precursor colored coating to form a photoresist coating. Subsequently, a mask is placed on the photoresist film, and ultraviolet rays are irradiated using an exposure device. After the exposure, the photoresist coating and the polyimide precursor colored coating are simultaneously etched with a positive photoresist alkaline developer. After etching, the photoresist film that is no longer needed is removed. The polyimide precursor colored film is then converted into a polyimide colored film by heat treatment.

When the ester portion of the polyamic acid ester in the color paste contains a photoreactive carbon-carbon unsaturated bond, the following steps are taken. After applying the color paste on the transparent substrate, air dry,
The photosensitive polyimide precursor colored film is formed by heat drying, vacuum drying, or the like. Subsequently, a mask is placed on the photosensitive polyimide precursor colored film, and ultraviolet rays are irradiated using an exposure device. After the exposure, the photosensitive polyimide precursor colored film is etched with a photosensitive polyimide precursor developing solution. The photosensitive polyimide precursor colored coating is then
By heat treatment, it is converted into a polyimide colored film.

As the developing solution for the photosensitive polyimide precursor, when the esterification rate of the photosensitive polyimide precursor is high, a lactone or an amide-based polar organic solvent is the main component, and in some cases, a small amount of water is added. When the esterification rate is low, an alkaline aqueous solution can be used as the organic solvent-based developer.

A color filter for a liquid crystal display can be manufactured by carrying out the above steps for three color pastes of R (red), G (green) and B (blue) and, if necessary, black color paste. .

[0038]

EXAMPLES The present invention will now be described in detail with reference to Examples, but the present invention is not limited thereto.

Example 1 300 equipped with a thermometer and a dry nitrogen inlet and a stirrer
In a 0 ml four-necked flask, 147.1 g of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (0.5
Molar equivalent), ethanol 46.1 g (1 molar equivalent), N
-Methyl-2-pyrrolidone (1000 g) was added, and the mixture was stirred at 60 ° C for 6 hours under a dry nitrogen flow to obtain a homogeneous solution.
The solution is cooled and thionyl chloride 119.0 g at -5 ° C.
(1 molar equivalent) was added dropwise, and after stirring for 1 hour, 4,4 '
-Diaminodiphenyl ether 140.2 g (0.7 molar equivalent), bis-3- (aminopropyl) tetramethylsiloxane 12.4 g (0.05 molar equivalent), and N
-Methyl-2-pyrrolidone (500 g) was added, and the mixture was stirred at 40 ° C for 4 hours while flowing dry nitrogen. 2000 this solution
The mixture was added dropwise to 0 ml of water to precipitate the polyamic acid ester. The precipitate was washed with water and then with methanol, and dried in vacuum to obtain a polyamic acid ester powder. 3000 ml of 4 equipped with thermometer and dry nitrogen inlet and stirrer
To a two-necked flask, 172.9 g of powder and 500 g of γ-butyrolactone were charged, and the mixture was stirred at 50 ° C. for 3 hours under a flow of dry nitrogen to obtain a homogeneous solution. 3,3 ', 4,4
73.6 g of ′ -biphenyltetracarboxylic dianhydride
(0.25 molar equivalent), 200 g of γ-butyrolactone was added and stirred for 1 hour, and then 25.0 g of 4,4′-diaminodiphenyl ether (0.125 molar equivalent) and 114.5 g of γ-butyrolactone were added. The mixture was added and stirred for 2 hours to obtain a γ-butyrolactone solution of polyamic acid (polymer concentration 25% by weight). Take 10 g of this solution,
18 g of γ-butyrolactone and 3.3 g of butyl cellosolve were added thereto to obtain a solution having a polymer concentration of 8% by weight.

Pigment Red 177 (Chromophtal red) 4 g, γ-butyrolactone 40 g and butyl cellosolve 6 g were dispersed together with 100 g of glass beads using a homogenizer at 7,000 rpm for 30 minutes, and the glass beads were removed by filtration.

To 20 g of the pigment dispersion, 20 g of a solution having a polymer concentration of 8% by weight was added and mixed to obtain a color paste of the present invention. This color paste was spin-coated on a non-alkali glass substrate, 90 ° C. for 10 minutes, and 110 ° C. for 20 minutes.
Heat dried in air using an oven for 1 minute to obtain a film thickness of 1.
A 6 μm polyimide precursor film was obtained. A positive photoresist (OFPR-800 manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied on this film and dried by heating at 80 ° C. for 20 minutes to obtain a resist film having a film thickness of 1 μm. Ultraviolet rays were irradiated through a chromium photomask using an ultraviolet exposure device. After the exposure, the photoresist and the colored film of the polyimide precursor were developed at the same time by immersing in a developing solution composed of a 2.38 wt% aqueous solution of tetramethylammonium hydroxide. After etching, the unnecessary photoresist layer was peeled off with methyl cellosolve acetate. Further, the polyimide precursor colored film thus obtained was used in a nitrogen atmosphere for 30 minutes.
It was heat-treated at 0 ° C. for 30 minutes to obtain a 1.2 μm-thick polyimide colored coating film.

The surface roughness of this film was measured by a surface roughness measuring device and found to be 0.006 μm. In addition, the brightness when the polarizer and the analyzer were parallel and vertical was measured with a microspectrophotometer, and the ratio (contrast) was determined. The contrast was 680.

Comparative Example 1 Instead of γ-butyrolactone in Example 1, N-methyl-
A color paste was obtained using 2-pyrrolidone. Using this, a patterned film thickness of 1.2
A polyimide colored coating of μm was obtained.

The surface roughness of this film was measured and found to be 0.
It was 074 μm. The contrast was 270.

Example 2 300 equipped with a thermometer and a dry air inlet and a stirrer
In a 0 ml four-necked flask, 193.3 g of 3,3 ′, 4,4′-benzophenone tetracarboxylic acid dianhydride
(0.6 molar equivalent), 156.2 g of hydroxyethyl methacrylate (1.2 molar equivalent), and 1000 g of N-methyl-2-pyrrolidone were added, and the mixture was stirred at room temperature for 100 hours under a flow of dry air to give a homogeneous solution. Got The solution was cooled, thionyl chloride (142.8 g, 1.2 molar equivalents) was added dropwise at -5 ° C, and the mixture was stirred for 1 hour. Then, m-phenylenediamine (54.1 g, 0.5 molar equivalent), 4,4. ′ -Diaminodiphenyl ether 140.2 g (0.25 molar equivalent), bis-3- (aminopropyl) tetramethylsiloxane 12.4 g (0.05 molar equivalent), and N-methyl-2-pyrrolidone 500 g It was charged and stirred at 40 ° C. for 4 hours while flowing in dry air. This solution is 20,000m
It was dripped at 1 l of water to precipitate the polyamic acid ester. The precipitate was washed with water and then with methanol, and dried in vacuum to obtain a polyamic acid ester powder. Into a 3000 ml four-necked flask equipped with a thermometer, a dry air inlet and a stirrer, 278.1 g of powder and 500 g of γ-butyrolactone were charged, and the mixture was stirred at 40 ° C. for 3 hours under a flow of dry air to obtain a homogeneous mixture. A solution was obtained. 43.6 g (0.2 mol equivalent) of pyromellitic anhydride and 200 g of γ-butyrolactone were added to this and stirred for 1 hour, and then 20.0 g (0.1 mol of 4,4′-diaminodiphenyl ether) was added. Equivalent)
And 97.3 g of γ-butyrolactone were added and stirred for 2 hours to obtain a γ-butyrolactone solution of a polyamic acid (polymer concentration 30% by weight). 15 g of this solution was taken out, and 25 g of γ-butyrolactone and 5 g of butyl cellosolve were added thereto to obtain a solution having a polymer concentration of 10% by weight.

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 together with 120 g of glass beads were dispersed with glass homogenizer at 7,000 rpm for 30 minutes. The beads were removed by filtration.

0.2 g of Michler's ketone and 0.1 g of N-phenylglycine were added to 24 g of a solution having a polymer concentration of 10% by weight.
Was dissolved and 16 g of the pigment dispersion was added and mixed to obtain a color paste of the present invention. This color paste is spin-coated on a non-alkali glass substrate, and the temperature is 100 ° C.
Heat dried in air using an oven for 1 minute to obtain a film thickness of 1.
A 6 μm photosensitive polyimide precursor colored coating was obtained. . Ultraviolet rays were irradiated through a chromium photomask using an ultraviolet exposure device. After the exposure, the photosensitive polyimide precursor colored film was developed by immersing it in a developing solution composed of a 2.38 wt% aqueous solution of tetramethylammonium hydroxide. Further, the photosensitive polyimide precursor colored film thus obtained was heat-treated at 290 ° C. for 40 minutes in a nitrogen atmosphere to obtain a polyimide colored film having a thickness of 1.1 μm.

The surface roughness of this film was 0.008 μm. The contrast was 540.

Example 3 200 equipped with a thermometer and dry nitrogen inlet and a stirrer
In a 0 ml 4-necked flask, pyromellitic dianhydride 8
7.2 g (0.4 molar equivalent), methanol 25.6 g
(0.8 molar equivalent), N-methyl-2-pyrrolidone 50
0 g was added, and the mixture was stirred at 50 ° C. for 6 hours under a flow of dry nitrogen to obtain a homogeneous solution. This solution was cooled, and 95.2 g (0.8 molar equivalent) of thionyl chloride was added dropwise at -5 ° C, and 1
After stirring for 3 hours, 161.3 g (0.65 molar equivalent) of 3,3′-diaminodiphenyl sulfone and 12.4 g of bis-3- (aminopropyl) tetramethylsiloxane
(0.05 molar equivalent) and N-methyl-2-pyrrolidone (500 g) were added, and the mixture was stirred at 40 ° C. for 4 hours while flowing dry nitrogen. This solution was added dropwise to 20000 ml of water,
The polyamic acid ester was precipitated. The precipitate was washed with water and then with methanol, and dried in vacuum to obtain a polyamic acid ester powder. To a 2000 ml four-necked flask equipped with a thermometer, a dry nitrogen inlet, and a stirrer, 143.3 g of the powder and 400 g of γ-butyrolactone were charged, and the mixture was stirred at 50 ° C. for 3 hours under an inflow of dry nitrogen to obtain a homogeneous mixture. A solution was obtained. Then, 88.3 g (0.3 molar equivalent) of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride,
After adding 200 g of γ-butyrolactone and stirring for 1 hour, 3,4 g of 4,4′-diaminodiphenyl ether was added.
(0.15 molar equivalent), and γ-butyrolactone 18
4.8 g was added, and the mixture was stirred for 2 hours, then the polyamic acid γ-
A butyrolactone solution (polymer concentration 25% by weight) was obtained. 120 g of this solution was taken out, and 50 g of γ-butyrolactone, 50 g of N-methyl-2-pyrrolidone and 30 g of butyl cellosolve were added thereto to obtain a solution having a polymer concentration of 12% by weight.

62.5 g of this solution and Pigment Blue 1
Glass beads 1 with 2.5 g of 5 (phthalocyanine blue)
Using a homogenizer with 50g, 7,000 rpm
After 30 minutes of dispersion treatment, the glass beads were removed by filtration to obtain the color paste of the present invention. Using this color paste, the same operation as in Example 1 was performed to obtain a film thickness of 1.2 μm.
A patterned polyimide colored coating of m was obtained.

The surface roughness of this film was 0.004 μm. The contrast was 920.

On this film, the red color paste prepared in Example 1 was applied, and then pattern processing was performed.
No abnormality was observed in this blue colored coating.

Comparative Example 2 On the patterned blue colored coating film obtained in Example 3, the red color paste prepared in Comparative Example 1 was applied,
After that, when pattern processing was performed, cracks occurred in the blue colored film.

[0054]

Since the present invention is constructed as described above, there is an advantage that a flat color filter having a large contrast can be formed. Further, according to the present invention, a remarkable effect that a multicolor patterned color filter can be formed even if a polyimide having poor solvent resistance is used.

Claims (4)

[Claims] 1. A color paste containing a pigment and a polyamic acid ester and containing a lactone as a main solvent. 2. The color paste according to claim 1, wherein the esterification rate of the polyamic acid ester is 10 to 90%. 3. The color paste according to claim 1, wherein the ester portion of the polyamic acid ester contains a photoreactive carbon-carbon unsaturated bond. 4. The color paste according to claim 1, which contains a photopolymerization initiator and / or a sensitizer.