JP2923007B2 - Solvent-soluble polyimide, method for producing the same, and material for color filter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyimide useful as an electronic material. More particularly, the present invention relates to a solvent-soluble polyimide excellent in transparency, a method for producing the same, and a color filter material using the soluble polyimide.

[Problems to be solved by conventional technology and invention]

Polyimide resins have high heat resistance and excellent electrical and mechanical properties, and are therefore widely used in electronic material applications. However, since the solubility in an organic solvent is poor, a method of applying a polyamic acid solution, which is a precursor thereof, to a base material and then firing the solution is generally used. The calcination is usually carried out at 250 to 450 ° C., in which volatilization of the solvent and imidation by dehydration of the amic acid are simultaneously carried out.

However, since such a high firing temperature is required,
When the base material contains a material having poor heat resistance such as an organic material, it cannot be used in many cases. If a polyimide soluble in a solvent is obtained, a polyimide coating film can be obtained only by evaporating the solvent, and sintering at such a high temperature can be avoided, and the application range of the polyimide can be expanded. . An object of the present invention is to provide a polyimide having excellent solubility in such a solvent and to provide a color filter material using the same.

[Means for solving the problem]

The first embodiment of the present invention comprises a repeating unit represented by the following general formula (I) as a main component, and has a logarithmic viscosity number of 0.1 to 5 dl measured in a solvent at a temperature of 30 ± 0.01 ° C. and a concentration of 0.5 g / dl. / g is a solvent-soluble polyimide, and the number of substitutions per substituent R ^{3 in} the following R ¹ is counted as 1;
The substitution number per CH _{2 q} as to count and 2, which substitution number average is characterized in that 0.5 to 4, it is.

However, in the formula (I), R ¹ is represented by the following formulas (II) and (II)
A group represented by I) or (IV), wherein R ² is a group represented by the following formula (V)
Is a group represented by

[However, the formulas (II), (III), (IV) and (V)
In the above, R ³ is each independently a methyl group or an ethyl group, and R ⁴ , R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom, a methyl group or an ethyl group, and at least one of them is Is a group other than a hydrogen atom, X is an oxygen atom, (However, R ⁸ is independently a hydrogen atom, a methyl group, an ethyl group or a trifluoromethyl group.) Or only a bond, p is an integer of 0 ≦ p ≦ 4,
q is independently an integer of 2 ≦ q ≦ 10, r is an integer of 0 ≦ r ≦ 2, and t is an integer of 1 to 3. In a second aspect of the present invention, a tetracarboxylic dianhydride represented by the following general formula (VI) and a diamine represented by the following formula (VII) are mixed in the presence of a solvent so as to be almost equimolar, Heating the polyamic acid obtained by performing the reaction at 0 to 100 ° C. to 110 to 200 ° C. in the presence of a solvent, or mixing a known imidization accelerator and imidizing at a temperature of room temperature to 100 ° C. A process for producing a polyimide soluble in a solvent characterized by the following. However, R ¹ and R ² have the same meaning as described above, and the average number of substitutions of R ^{1 in} the compound represented by the formula (VI) is 0.5 to 4.

A third aspect of the present invention is a transparent composition obtained by applying a solution containing a polyimide soluble in a solvent containing a repeating unit represented by the above general formula (I) as a main component to a substrate and baking it at 100 to 250 ° C. It is a color filter material with excellent properties.

The production method for obtaining the soluble polyimide of the present invention will be described.

The soluble polyimide of the present invention is obtained by reacting a polycarboxylic acid with a tetracarboxylic dianhydride represented by the formula (VI) and a diamine represented by the formula (VII) in an organic solvent at a temperature of 0 to 100 ° C. It can be obtained by heating or by using a known imidation method such as adding an imidization accelerator and performing an imidization reaction at room temperature or under heating.

The tetracarboxylic dianhydride represented by the formula (VI), which is a raw material of the polyamic acid, can be more specifically represented by the following general formulas (VIII) to (X).

Such a tetracarboxylic dianhydride can be obtained by a photoduplexing reaction of maleic anhydride and one or more specific mixtures of various alkyl-substituted maleic anhydrides.

For example, the compound of the formula (VIII) can be obtained by reacting one or more of the following maleic anhydride and its alkyl-substituted derivatives.

The compound of the formula (IX) can be obtained by reacting the following alkylene-substituted maleic anhydride derivative with the maleic anhydride or an alkyl-substituted derivative thereof.

The compound represented by the formula (X) can be obtained by a double reaction of the alkylene-substituted derivative.

Specific examples of the alkyl-substituted or alkylene-substituted maleic anhydride shown above include the following compounds, but are not necessarily limited thereto.

Methyl maleic anhydride, 2,3-dimethyl maleic anhydride, 1-cyclohexane-1,2-dicarboxylic anhydride, ethyl maleic anhydride, 2-methyl-3-ethyl maleic anhydride, 2,3-diethyl maleic anhydride etc.

The diamine represented by the formula (VII) can be represented by the following formula.

Here, R ⁴ , R ⁵ , R ⁶ , R ⁷ , X and t have the same meaning as described above.

Specific examples of the above diamine include the following compounds, but are not necessarily limited thereto.

4,4'-diamino-3,3'-dimethyldicyclohexyl, 4,4'-diamino-3,3'-diethyldicyclohexyl, 4,4'-diamino-3,3'-dimethylcyclohexylmethanebis (4,4 '-Diamino-3,3'-dimethylcyclohexyloxy) dicyclohexyl, 2,2-bis (3-methyl, 4-aminocyclohexyloxycyclohexyl) propane, 2,2-bis (3-methyl, 4-aminocyclohexyloxycyclohexyl) ) Hexafluoropropane, bis (3-methyl, 4-aminocyclohexyloxycyclohexyl) sulfone and the like.

The compound having the structure represented by the formula (I) can be obtained by a combination of the tetracarboxylic dianhydride represented by the formula (VI) and the diamine represented by the formula (VII). Less than 20 mol% of the dianhydrides can be replaced by other tetracarboxylic dianhydrides, such as the following compounds.

Pyromellitic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 2,3,3', 4'-benzophenonetetracarboxylic dianhydride, 2,2 ', 3,3'-Benzophenonetetracarboxylic dianhydride, bis (3,4-
Dicarboxyphenyl) -ether dianhydride, bis (3,
4-dicarboxyphenyl) -sulfone dianhydride, 1,2,
5,6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-
Naphthalenetetracarboxylic dianhydride, 2,2-bis (3,4
-Dicarboxyphenyl) aromatic tetracarboxylic dianhydrides such as tetrafluoropropane dianhydride. Or 1,2,3,4
An aliphatic tetracarboxylic dianhydride such as tetracarboxybutane dianhydride;

Of the diamines represented by the above formula (VII), 20
Less than mol% of the other diamine can be used, such as the following compounds:

4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfide, 4,4'- Di (meth-aminophenoxy) diphenylsulfone, 4,4'-di (para-aminophenoxy) diphenylsulfone, ortho-phenylenediamine, meta-phenylenediamine, para-
Phenylenediamine, benzidine, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 4,4 '
-Diaminodiphenyl-2,2'-propane, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 3,4'-diaminodiphenylether, 4,4'-bis (4-aminophenoxy) biphenyl, 2,2 -Bis {4- (4-aminophenoxy) phenyl} hexafluoropropane, 1,4-
Bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-
Aminophenoxy) benzene, 4,4'-diamino-3,3 '
-Diethyl-5,5'dimethyldiphenylmethane, 4,4'-
Aromatic diamines such as diamino-3,3 ', 5,5'-tetramethyldiphenylmethane, 1,4-diaminotoluene, meta-xylylenediamine, 2,2'-dimethylbenzidine;
Aliphatic diamines such as trimethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4-dimethylheptamethylenediamine, and 2,11-dodecanediamine;
Bis (p-aminophenoxy) dimethylsilane, 1,4-
Silicon-based diamines such as bis (3-aminopropyldimethylsilyl) benzene; 1,4-diaminocyclohexane;
Alicyclic diamines such as bis (4-aminocyclohexyl) methane and isophoronediamine; and guanamines such as acetoguanamine and benzoguanamine. Alternatively, the following siloxane bond-containing diamine can be used.

In order to improve the adhesion to the substrate, aminosilane of 10 mol% or less of the whole raw material can be added. Specific examples are shown below.

Aminomethyl-di-n-propoxy-methylsilane,
(Β-aminoethyl) -di-n-propoxy-methylsilane, (β-aminoethyl) -diethoxy-phenylsilane, (β-aminoethyl) -tri-n-propoxysilane, (β-aminoethyl) -dimethoxy- Methylsilane, (γ-aminopropyl) -di-n-propoxy-methylsilane, (γ-aminopropyl) -di-n-butoxy-methylsilane, (γ-aminopropyl) -trimethoxysilane, (γ-aminopropyl)- Triethoxysilane, (γ-aminopropyl) -di-n-pentoxy-
Phenylsilane, (γ-aminopropyl) -methoxy-
n-propoxy-methylsilane, (δ-aminobutyl)
-Dimethoxy-methylsilane, (3-aminophenyl)
-Di-n-propoxy-methylsilane, (4-aminophenyl) -tri-n-propoxysilane, {β- (4-
Aminophenyl) -ethyl} -diethoxy-methylsilane, {β- (3-aminophenyl) -ethyl} -di-n
-Propoxy-phenylsilane, {γ- (4-aminophenyl) -propyl} -di-n-propoxy-methylsilane, {γ- (4-aminophenoxy) -propyl}-
Di-n-propoxy-methylsilane, {γ- (3-aminophenoxy) -propyl} -di-n-butoxy-methylsilane, (γ-aminopropyl) -methyl-dimethoxysilane, (γ-aminopropyl) -methyl- Diethoxysilane, (γ-aminopropyl) -ethyl-di-n-
Propoxysilane, (4-aminophenyl) -trimethoxysilane, (3-aminophenyl) -trimethoxysilane, (4-aminophenyl) -methyl-dimethoxysilane, (3-aminophenyl) -dimethyl-methoxysilane, ( 4-Aminophenyl) -triethoxysilane.

In the present invention, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide are preferred solvents (hereinafter, sometimes referred to as reaction solvents) for reacting the above-mentioned raw material compounds in a solvent. Dimethylsulfoxide, tetramethylurea, pyridine, hexamethylphosphoramide, methylformamide, N-acetyl-2-pyrrolidone, 2-methoxyethanol,
-Ethoxyethanol, 2-butoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, cyclopentanone, cyclohexanone, cresol, γ-butyrolactone, isophorone,
N, N, -diethylacetamide, N, N-diethylformamide, N, N-dimethylmethoxyacetamide, tetrahydrofuran, N-acetyl-2-pyrrolidone, N-methyl-ε-caprolactam, tetrahydrothiophenedioxide disulfolane (sulpho- Lane)}. This reaction can also be performed in a mixed solvent obtained by mixing the above organic solvents. Further, the preferred organic solvent as described above is replaced with another aprotic (neutral) organic solvent,
For example, aromatic, cycloaliphatic or aliphatic hydrocarbons, or their chlorinated derivatives (eg, benzene, toluene,
Xylenes, cyclohexane, pentane, hexane, petroleum ether, methylene chloride, etc.), or those diluted with dioxane, etc. can also be used.

Among the above solvents, N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-
Dimethyl sulfoxide, cyclopentanone and γ-butyrolactone are particularly preferred from the viewpoint of solubility.

Next, the reaction method will be described. A tetracarboxylic dianhydride containing not less than 80 mol% of the tetracarboxylic dianhydride represented by the formula (VI), a diamine containing not less than 80 mol% of the diamine represented by the formula (VII), and 0
〜10 mol% of the aminosilane is reacted in the reaction solvent. Further, the total amount of tetracarboxylic dianhydride and the total amount of amine are set to be approximately equimolar. However, either of them can be excessive within 10 mol%.

The reaction solvent is preferably used in an amount of 50% by weight or more based on the total amount of the reaction solvent and the added raw materials. If the amount of solvent is less than this, stirring may be difficult, which is not preferable. The reaction may be any method as long as it is a method of synthesizing a polyimide precursor which is usually performed, but the raw materials are collectively or separately supplied in a solvent and supplied to the reactor at a temperature of 0 to 100 ° C. for several hours to several tens of hours. It is common to do. By heating the polyimide precursor thus obtained in the presence of a solvent at 110 to 200 ° C. for several minutes to several tens of hours, a dehydration reaction is carried out, whereby the soluble polyimide of the present invention can be obtained. The imidation ratio of this polyimide is desirably 80% or more. At the time of this reaction, completion of the imidization reaction can be expedited by removing water out of the system. Alternatively, imidization can be carried out at a relatively low temperature of 100 ° C. or less by mixing a polyimide precursor solution with a dehydrating agent such as acetic anhydride and / or a known imidization accelerator such as pyridine or isoquinoline. These dehydrating agents and imidization accelerators have some effect even when added at about 1/10 mole of the carboxylic acid in the polyamic acid, but preferably at least equimolar.

The average molecular weight of the polyimide precursor of the present invention is preferably such that the logarithmic viscosity number measured under the above-mentioned constant conditions is in the range of 0.1 to 5 dl / g.

In the present invention, the logarithmic viscosity number (η _inh ) is as defined by the measurement conditions. (Here, η is measured using a Ubbelohde viscometer at a concentration of 0.5 g / dl in a solvent having the same composition as the polymerization solvent at a temperature of 30 ± 0.01 ° C.
Η ₀ is a measured value of the same solvent at the same temperature using an Ubbelohde viscometer, and C is a concentration of 0.
5 g / dl. Next, a method for using the soluble polyimide of the present invention will be described. In most cases, the polyimide of the present invention is used in the form of a solution dissolved in a solvent. Therefore, it is preferable to use the reaction solution as it is, by concentrating it, or diluting it with a solvent. As the diluting solvent, the same solvent as the reaction solvent can be used.

When a polyimide cured film is formed from a solution containing the soluble polyimide of the present invention, any known method may be used. For example, a cured film can be obtained by applying a solution containing the soluble polyimide of the present invention onto a substrate such as a glass plate, a copper plate, an aluminum plate, or a silicon wafer and baking the solution at a temperature of 100 to 450 ° C. However, since the soluble polyimide of the present invention is already an imidized polymer, it is only necessary to volatilize the solvent in the solution, and by firing at a relatively low temperature of 100 to 250 ° C. for several minutes to several hours, a cured film is obtained. Can be obtained. In this case, the coating method may be any method, but is usually selected from a spin coating method, a printing method, a dipping method, a roll coater method and the like.

As a use of the soluble polyimide of the present invention, a color filter-related material such as a color filter substrate and a protective film thereof is particularly preferable.

A color filter used for a color liquid crystal display cell or an imaging element is usually made of gelatin or an acrylic resin material, and its heat-resistant temperature is said to be about 200 ° C. However, as described above, in the case of ordinary polyimide, a firing temperature of 250 to 450 ° C. is required to complete imidization, which is not preferable for such use. Since the soluble polyimide of the present invention can be fired at a low temperature, it is easy to form a coating film on a color filter. Furthermore, the cured polyimide film of the present invention has good visible light transmittance. That is, since it is highly transparent, it is suitably used as a color filter protective film, and by dispersing or dissolving an organic pigment or dye in the soluble polyimide solution of the present invention, a colored paste for a color filter can be easily obtained. Can be. This colored paste is applied to a substrate by any of the application methods described above,
By firing this, a color filter can be obtained. As the pigment, for example, red quinacridone red, green phthalocyanine green, blue phthalocyanine blue and the like can be used. The proportion of the pigment or dye added is 10 to 200% by weight of the polymer, preferably 20 to 100% by weight.

The color filter substrate of the present invention can be used for a color liquid crystal display device or an image pickup device as well as the protective film. The cured film obtained from the soluble polyimide of the present invention has excellent heat resistance, mechanical properties and electrical properties, and is also suitable for various protective films for semiconductors, flattening films, insulating films, or alignment films for liquid crystals. Can be used for

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Reference Examples, Examples, and Comparative Examples. However, it is needless to say that the present invention is not limited to these Examples. The transparency of the polyimide was measured using a Shimadzu UV-210A spectrophotometer, which was applied to quartz glass and baked.

Reference Example 1 (Synthesis of tetracarboxylic dianhydride) 467 g of maleic anhydride (4.
76 mol), 534 g (4.76 mol) of citraconic anhydride and ethyl acetate 8 were charged, and nitrogen gas was blown into the solution.
While stirring, keep the reaction solution at 5-10 ° C while maintaining 4K
Irradiation was performed for 48 hours using a W high-pressure mercury lamp. The solvent was distilled off from the reaction solution, and toluene 2 was added to the residue to dissolve unreacted substances. Then, a composition containing an insoluble alkyl-substituted cyclobutanetetracarboxylic dianhydride was passed, and the mixture was added with toluene 1
, And dried under reduced pressure to obtain 663 g of a white powder. The compound was analyzed by H-NMR spectrum, and it was confirmed that the compound contained an average of 1.16 methyl groups per molecule.

Reference Examples 2 to 4, Comparative Reference Example 1 Synthesis was performed in the same manner as in Reference Example 1 except that the acid anhydride used as a raw material was changed.

 The results are shown in Table 1.

Example 1 One flask equipped with a stirrer, a dropping funnel, a thermometer, a condenser, and a nitrogen purge device was fixed in cold water. After the atmosphere in the flask was replaced with nitrogen gas, 500 g of dehydrated and purified N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) and 66.11 g (0.278 mol) of 4,4'-diamino-
3,3'-Dimethyldicyclohexylmethane (hereinafter abbreviated as HMDT) and 58.89 g (0.278 mol) of the tetracarboxylic dianhydride synthesized in Reference Example 1 were added, and the mixture was added at 20-30 ° C.
The polyamic acid solution was obtained by performing the reaction for a time.
This solution was slowly dropped into a large amount of a solution composed of 1:10 (molar ratio) of pyridine and acetic anhydride to obtain a pale yellow precipitate.

This was separated by filtration and dried to obtain 95.6 g of the soluble polyimide powder of the present invention. The logarithmic viscosity number of this polymer is
It was 0.54 dl / g, and the imidation ratio by infrared absorption spectrum was 92%. FIG. 1 shows an infrared absorption spectrum of this polymer measured by the Kbr tablet method.

Example 2 In the same apparatus and method as in Example 1, 500 g of N, N-dimethylacetamide (hereinafter abbreviated as DMAC) and 45.46 g (0.
191 mol) of HMDT and 42.78 g (0.191 mol) of the tetracarboxylic dianhydride synthesized in Reference Example 2 were added at 10 to 20 ° C.
For 10 hours to obtain a polyamic acid solution. Pyridine and acetic anhydride are 1:20 (molar ratio)
By gradually dropping into a large amount of a solution consisting of, a pale yellow precipitate was obtained. By filtering and drying this, 69.5
g of the soluble polyimide powder of the present invention was obtained. The logarithmic viscosity number of this polymer was 1.1 dl / g, and the imidation ratio by infrared absorption spectrum was 85%.

Example 3 500 g of NMP and 45.64 g using the same apparatus and method as in Example 1.
(0.179 mol) of tetracarboxylic dianhydride synthesized in Reference Example 3 and 42.60 g (0.179 mol) of HMDT were added, and 30
The polyamic acid solution was obtained by performing the reaction at 4040 ° C. for 5 hours. This solution was reacted at a temperature of 130 to 140 ° C. for 3 hours while removing generated water outside the system. By adding the obtained polyimide solution to a large amount of water, the precipitated pale yellow precipitate was separated by filtration and dried, so that the logarithmic viscosity number was 0.
At 33 dl / g, imidization rate by infrared absorption spectrum is 95
% Of the soluble polyimide powder of the present invention was obtained.

Example 4 500 g of NMP and 52.12 g using the same apparatus and method as in Example 1.
(0.219 mol) of HMDT and 6.04 g (0.0243 mol) of 3,3 '
50.62 g after dissolving diaminodiphenyl sulfone
(0.243 mol) of the tetracarboxylic dianhydride synthesized in Reference Example 4 was added, and the reaction was carried out at 20 to 30 ° C. for 7 hours to obtain a polyamic acid solution. 120-130 of this solution
The reaction was carried out at a temperature of 5 ° C. for 5 hours while removing generated water from the system. The resulting polyimide solution was added to a large amount of water, and the precipitated pale yellow precipitate was separated by filtration and dried. As a result, the logarithmic viscosity number was 0.42 dl / g, and the imidation ratio was 92%. 86.7 g of a polyimide powder was obtained.

Example 5 500 g of DMAC, 54.95 g, using the same apparatus and method as in Example 1.
(0.231 mol) of HMDT, 46.55 g (0.208 mol) of Reference Example 2
8.27 g (0.023 g) of tetracarboxylic dianhydride synthesized in
(1 mol) of diphenylsulfone-3,3 ', 4,4'-tetracarboxylic dianhydride and reacted at 30 to 40 ° C for 5 hours to obtain a polyamic acid solution. This solution was gradually dropped into a large amount of a solution containing isoquinoline and acetic anhydride at a molar ratio of 1:10 to obtain a pale yellow precipitate. This was filtered and dried to obtain 89.0 g of the soluble polyimide powder of the present invention. The logarithmic viscosity number of this polymer was 0.79 dl / g, and the imidation ratio by infrared absorption spectrum was 89%.

Example 6 500 g of NMP, 45.33 g using the same apparatus and method as in Example 1.
(0.202 mol) of 4,4'-diamino-3,3'-dimethyldicyclohexyl and 42.91 g (0.202 mol) of the tetracarboxylic dianhydride synthesized in Reference Example 1 were added, and 30 to 40 ° C.
For 5 hours to obtain a polyamic acid solution. 50 g of isoquinoline and 100 g of acetic anhydride were added to this solution, and the mixture was reacted at 80 to 90 ° C. for 5 hours, and then poured into a large amount of water to obtain a pale yellow precipitate. This was separated by filtration and dried to obtain 72.4 g of the soluble polyimide powder of the present invention. The logarithmic viscosity number of this polymer is 0.35dl
/ g, and the imidation ratio by infrared absorption spectrum is 83
%Met.

Comparative Example 1 500 g of NMP, 48.39 g using the same apparatus and method as in Example 1.
(0.203 mol) of HMDT and 39.85 g (0.203 mol) of the tetracarboxylic dianhydride synthesized in Comparative Reference Example 1 were added,
The polyamic acid solution was obtained by performing a reaction at 20 to 30 ° C. for 5 hours. This solution is mixed with pyridine and acetic anhydride at 1:10.
(Molar ratio), a light yellow precipitate was obtained by gradually dropping the solution into a large amount of the solution. This was filtered and dried to obtain 71.5 g of a polyimide powder. The logarithmic viscosity number of this polymer in concentrated sulfuric acid was 0.51 dl / g, and the imidation ratio by infrared absorption spectrum was 90%.

Comparative Example 2 Comparative Example 1 except that 43.91 g (0.209 mol) of 4,4'-diaminodicyclohexylmethane was used as the diamine and 44.33 g (0.209 mol) of the compound synthesized in Reference Example 1 was used as the tetracarboxylic dianhydride. Polyamide acid was synthesized and imidation reaction was carried out in the same manner as described above to obtain 73.2 g of a polyimide powder having a logarithmic viscosity number in concentrated sulfuric acid of 0.61 dl / g and an imidation ratio of 89% in an infrared absorption spectrum.

Solubility test A solubility test of the polyimide powder synthesized in Examples 1 to 6 and Comparative Examples 1 and 2 in the following solvents was performed. Each test was prepared so that the polyimide concentration was 10%.
Stirring was performed at 0 ° C. for 3 hours.

Solvents tested: N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-dimethylsulfoxide, cyclopentanone and γ-butyrolactone. Although the polyimide synthesized in the above was dissolved in any of the above solvents, the polyimide synthesized in Comparative Examples 1 and 2 was insoluble in any of the solvents.

Light transmittance test The polyimide powder synthesized in Examples 1 to 6 was dissolved in each NMP to prepare six kinds of varnishes having a polymer concentration of 20 to 30% by weight. This solution is spin-coated on quartz glass,
Table 2 shows the results of measuring the transmittance of the product baked at 30 ° C. for 30 minutes and then at 150 ° C. for 1 hour using a spectrophotometer.

 The thickness of each coating film is 10 μm.

Example 7 To a solution having a polymer concentration of 20% obtained by dissolving the polyimide powder synthesized in Example 1 in NMP, 3-aminopropyltriethoxysilane in an amount equivalent to 2% of this solution was added. Was prepared. To 120 g of this solution was added 25 g of powdery phthalocyanine blue, and the mixture was kneaded with an automatic mortar to prepare a varnish for a blue colored color filter. This varnish is
After coating on a glass plate, 15 minutes at 60 ° C under nitrogen atmosphere
By baking at 0 ° C. for 1 hour, a colored color filter was formed on the glass plate. Visually, the pigment phthalocyanine blue was uniformly dispersed, and a clear blue color filter was obtained. Further, for the purpose of forming a protective film on this color filter, the above-mentioned solution containing no pigment was similarly applied and baked. Thus, a protective film having a transparent and smooth surface was formed on the color filter. In addition, the adhesiveness between the glass plate and the color filter and between the color filter and the protective film were all good by a scotch tape test with a 2 mm square section using cellophane tape.

Example 8 A film of about 1 μm of an acrylic color filter material (CFP-7215NB manufactured by Chisso Corporation) was formed on a glass plate, and the film was dyed with a red dye (21P manufactured by Nippon Kayaku Co., Ltd.). A solution of the polyimide powder synthesized in Example 1 dissolved in cyclopentanone at a polymer concentration of 15% was applied by spin coating and heated at 150 ° C. for 1 hour to form a protective film on the color filter. The film was observed and it was examined whether or not the dye had transferred to the protective film. As a result, the film was transparent and no transfer of the dye was observed.

〔The invention's effect〕

Since the polyimide of the present invention has excellent solubility in a solvent, it can be dissolved in a solvent to form a solution and applied to a substrate. Then, a polyimide film can be formed at a temperature low enough to evaporate the solvent, and a coating film can be formed on a substrate having poor heat resistance, so that the practical effect is large. In addition, since the coating film has excellent transparency, it is possible to provide a material suitable as a material for a color filter substrate and a protective film thereof.

[Brief description of the drawings]

FIG. 1 is a chart of an infrared absorption spectrum of the polyimide synthesized in Example 1. The absorption of an imide group is observed at the position of 1770 cm ^-1 .

Claims (3)

(57) [Claims] 1. A logarithmic viscosity number of 0.1 to 5 dl / g, which is mainly composed of a repeating unit represented by the following general formula (I) and measured in a solvent at a temperature of 30 ± 0.01 ° C. and a concentration of 0.5 g / dl. R ¹ is a polyimide, and the number of substitutions per one substituent R ³ described below is counted as 1 and the number of substitutions per one substituent CH _{2 q is} counted as 2 in R ₁ described below. A polyimide, wherein the average number of substitutions per one is 0.5 to 4. However, in the formula (I), R ¹ is represented by the following formulas (II) and (II)
It is a group represented by I) or (IV), and R ² is a group represented by the following formula (V). [However, the formulas (II), (III), (IV) and (V)
In the above, R ³ is each independently a methyl group or an ethyl group, and R ⁴ , R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom, a methyl group or an ethyl group, and at least one of them is Is a group other than a hydrogen atom, X is an oxygen atom, (However, R ⁸ is independently a hydrogen atom, a methyl group, an ethyl group or a trifluoromethyl group.) Or only a bond, p is an integer of 0 ≦ p ≦ 4,
q is independently an integer of 2 ≦ q ≦ 10, r is an integer of 0 ≦ r ≦ 2, and t is an integer of 1 to 3. ] 2. A tetracarboxylic dianhydride represented by the following general formula (VI) and a diamine represented by the formula (VII) are mixed in the presence of a solvent so as to be almost equimolar.
Polyimide acid obtained by performing the reaction at 110 ° C. in the presence of a solvent is heated to 110 to 200 ° C. or mixed with an imidization accelerator, a polyimide characterized by being imidized at a temperature of room temperature to 100 ° C. Manufacturing method. However, R ¹ and R ² have the same meanings as described above, and the formula (VI)
The average number of substitutions of R ¹ is 0.5 to 4 in all of the compounds represented by 3. A solution containing a polyimide containing a repeating unit represented by the general formula (I) as a main component and applied to a substrate.
A material for a color filter obtained by firing at 100 to 250 ° C.