TWI777005B - Polyimide resin, polyimide varnish, and polyimide film - Google Patents

Abstract

The invention provides a polyimide resin having a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, wherein the structural unit A includes a structural unit (A-1) derived from a compound represented by formula (a-1) shown below, a structural unit (A-2) derived from a compound represented by formula (a-2) shown below, and a structural unit (A-3) derived from a compound represented by formula (a-3) shown below, and the structural unit B includes a structural unit (B-1) derived from a compound represented by formula (b-1) shown below. The invention also provides a polyimide varnish and polyimide film containing this polyimide resin.

Description

Polyimide resin, polyimide varnish and polyimide film

The present invention relates to polyimide resins, polyimide varnishes and polyimide films.

Since polyimide resins have excellent mechanical properties and heat resistance, various applications of the polyimide resins in the fields of electric-electronic parts and the like have been investigated. For example, for the purpose of reducing the weight and flexibility of devices, it is desirable to replace glass substrates used in image display devices such as liquid crystal displays and OLED displays with plastic substrates, and research on polyimide resins suitable as plastic materials There is also progress. Colorless transparency is also required for the polyimide resin used for this purpose, and high dimensional stability to heat (ie, low coefficient of linear thermal expansion) is also required in order to be able to cope with high temperature processing in the manufacturing steps of image display devices.

For a polyimide resin having a low coefficient of linear thermal expansion, for example, Patent Document 1 describes that a first tetracarboxylic acid component such as pyromellitic anhydride, 3,3',4,4'-diphenyltetracarboxyl A polyimide resin synthesized from a second tetracarboxylic acid component such as acid dianhydride and a tolidine sulfone skeleton diamine component, Patent Document 2 describes a diamine compound containing a benzoxazole group and an aromatic Polyimide resin synthesized from tetracarboxylic dianhydride.

In addition, in the field of microelectronics in recent years, a method of peeling off the resin film-laminated support from the resin film is called laser lift-off (LASER LIFT-OFF; LLO). Laser lift-off processing is attracting attention. Therefore, in order to make the polyimide film compatible with the laser peeling process, the laser peelability is also required for the polyimide film. In order to make it suitable for the exfoliation processing by the XeCl excimer laser with a wavelength of 308 nm, the polyimide film is required to have excellent light absorption characteristics of the wavelength of 308 nm (that is, the light transmittance at the wavelength of 308 nm is small).

Furthermore, the polyimide film is also required to have resistance to organic solvents such as polar solvents (organic solvent resistance). When a film with poor resistance to organic solvents is exposed to an organic solvent such as a polar solvent, the morphology of the film may change due to elution or swelling of the surface. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2010-053336 [Patent Document 2] Japanese Patent Laid-Open No. 2015-093915

[The problem to be solved by the invention]

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a film capable of forming a film having excellent mechanical properties and heat resistance, and excellent in colorless transparency, dimensional stability to heat, laser peelability, and organic solvent resistance. Polyimide resin and polyimide varnish and polyimide film containing the polyimide resin are provided. [Means of Solving Problems]

The inventors of the present invention have found that a polyimide resin containing a combination of specific structural units can solve the above-mentioned problems, and completed the present invention.

That is, the present invention relates to the following [1] to [5]. [1] A polyimide resin having a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from a diamine, This structural unit A contains a structural unit (A-1) derived from a compound represented by the following formula (a-1), a structural unit (A-2) derived from a compound represented by the following formula (a-2), and a structural unit (A-2) derived from the following formula ( The constituent unit (A-3) of the compound represented by a-3), This structural unit B contains a structural unit (B-1) derived from a compound represented by the following formula (b-1).

【Change 1】

[2] Such as the polyimide resin of [1], wherein, The ratio of the structural unit (A-1) in the structural unit A is 10 to 80 mol %, The ratio of the structural unit (A-2) in the structural unit A is 10 to 80 mol %, The ratio of the structural unit (A-3) in the structural unit A is 10 to 80 mol %. [3] The polyimide resin according to [1] or [2], wherein the ratio of the constituent unit (B-1) in the constituent unit B is 50 mol % or more. [4] A polyimide varnish is prepared by dissolving the polyimide resin according to any one of [1] to [3] in an organic solvent. [5] A polyimide film comprising the polyimide resin according to any one of [1] to [3]. [Effect of invention]

According to the present invention, a film having good mechanical properties and heat resistance, and excellent in colorless transparency, dimensional stability to heat, laser releasability, and organic solvent resistance can be formed. In the present invention, excellent colorless transparency means that the total light transmittance is high and the yellowness index is small, and excellent dimensional stability to heat means that the linear thermal expansion coefficient is low.

[Polyimide resin] The polyimide resin of the present invention is a polyimide resin having a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from a diamine, and the structural unit A contains a compound derived from the following formula (a-1) The constituent unit (A-1), the constituent unit (A-2) derived from the compound represented by the following formula (a-2), and the constituent unit (A-3) derived from the compound represented by the following formula (a-3), The structural unit B contains the structural unit (B-1) derived from the compound represented by the following formula (b-1).

【Change 2】

<Construction Unit A> Structural unit A is the constituent unit derived from tetracarboxylic dianhydride in the polyimide resin, including the constituent unit (A-1) derived from the compound represented by formula (a-1), and the constituent unit derived from formula (a-2) The constituent unit (A-2) of the compound represented, and the constituent unit (A-3) derived from the compound represented by the formula (a-3). By the structural unit (A-1), the colorless transparency and dimensional stability will be improved, and by the structural unit (A-2), the laser peeling property and organic solvent resistance will be improved, and by the structural unit (A-3) ), will improve colorless transparency. The compound represented by formula (a-1) is norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetra Carboxylic acid dianhydride. The compound represented by formula (a-3) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride.

The compound represented by the formula (a-2) is biphenyltetracarboxylic dianhydride (BPDA), and specific examples thereof include 3,3',4,4'-biphenyltetracarboxylic acid represented by the following formula (a-2s). Dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) represented by the following formula (a-2a), 2 represented by the following formula (a-2i) ,2',3,3'-biphenyltetracarboxylic dianhydride (i-BPDA).

【Change 3】

The ratio of the constituent unit (A-1) in the constituent unit A is preferably 10-80 mol %, more preferably 15-55 mol %, more preferably 20-45 mol %, particularly preferably 22.5-40 mol % Mol%. The ratio of the structural unit (A-2) in the structural unit A is preferably 10-80 mol %, more preferably 20-60 mol %, more preferably 25-50 mol %, particularly preferably 27.5-45 mol % Mol%. The ratio of the constituent unit (A-3) in the constituent unit A is preferably 10-80 mol %, more preferably 25-65 mol %, more preferably 30-55 mol %, particularly preferably 32.5-50 mol % Mol%. The total ratio of the constituent units (A-1) to (A-3) in the constituent unit A is preferably 50 mol % or more, more preferably 70 mol % or more, still more preferably 90 mol % or more, particularly preferably is more than 99 mol%. The upper limit of the total ratio of the constituent units (A-1) to (A-3) is not particularly limited, and is 100 mol %. The structural unit A may be constituted only by the structural unit (A-1), the structural unit (A-2), and the structural unit (A-3).

The structural unit A may contain structural units other than the structural units (A-1) to (A-3). The tetracarboxylic dianhydride that provides such a structural unit is not particularly limited, and examples thereof include aromatic tetracarboxylic acids such as pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride. Dianhydride (but not including the compound represented by formula (a-2)); alicyclic tetracarboxylic dianhydride such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride (but not including formula (a- The compound represented by 1) and the compound represented by formula (a-3)); and aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride. In addition, in this specification, aromatic tetracarboxylic dianhydride means tetracarboxylic dianhydride containing one or more aromatic rings, and alicyclic tetracarboxylic dianhydride means containing one or more alicyclic rings and does not contain aromatic Cyclic tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydride mean tetracarboxylic dianhydride containing neither aromatic ring nor alicyclic ring. The structural units (that is, structural units other than structural units (A-1) to (A-3)) arbitrarily contained in the structural unit A may be one type or two or more types.

<Construction unit B> Structural unit B is the structural unit derived from the diamine occupied in the polyimide resin, and contains the structural unit (B-1) derived from the compound represented by formula (b-1). By constituting the unit (B-1), mechanical properties and dimensional stability are improved. The compound represented by the formula (b-1) is 2,2'-bis(trifluoromethyl)benzidine.

The ratio of the structural unit (B-1) in the structural unit B is preferably 50 mol % or more, more preferably 70 mol % or more, still more preferably 90 mol % or more, and particularly preferably 99 mol % or more. The upper limit value of the ratio of the constituent unit (B-1) is not particularly limited, that is, 100 mol %. The structural unit B may be composed of only the structural unit (B-1).

The structural unit B may contain structural units other than the structural unit (B-1). The diamine that provides such a structural unit is not particularly limited, and examples thereof include 1,4-phenylenediamine, p-xylylenediamine, 3,5-diaminobenzoic acid, and 2,2'-dimethylbiphenyl -4,4'-diamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)hexafluoropropane , bis(4-aminophenyl) bismuth, 4,4'-diaminobenzidine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-tri Methyl-1H-indene-5-amine, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, N,N'-bis(4-aminophenyl) terephthalamide, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2 -Aromatic diamines such as bis(4-(4-aminophenoxy)phenyl)hexafluoropropane, and 9,9-bis(4-aminophenyl)pyridine (excluding formula (b-1) ); alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane; and ethylenediamine and hexamethylene aliphatic diamines such as diamines. In addition, in this specification, an aromatic diamine means a diamine containing one or more aromatic rings, an alicyclic diamine means a diamine containing one or more alicyclic rings and no aromatic ring, and an aliphatic diamine Means a diamine containing neither an aromatic ring nor an alicyclic ring. The structural unit arbitrarily contained in the structural unit B (that is, structural units other than the structural unit (B-1)) may be one type or two or more types.

The number average molecular weight of the polyimide resin of the present invention is preferably 5,000 to 100,000 in view of the mechanical strength of the obtained polyimide film. In addition, the number average molecular weight of polyimide resin can be calculated|required from the standard polymethyl methacrylate (PMMA) conversion value measured by gel filtration chromatography, for example.

The polyimide resin of the present invention can form a film with good mechanical properties and heat resistance, and excellent in colorless transparency, dimensional stability to heat, laser peelability and organic solvent resistance. The desirable physical property values of the thin film which can be formed using the polyimide resin of the present invention are as follows.

The tensile strength is preferably 80 MPa or more, more preferably 100 MPa or more, and still more preferably 110 MPa or more. The tensile elastic modulus is preferably 2.5GPa or more, more preferably 3.0GPa or more, and still more preferably 3.2GPa or more. The glass transition temperature (Tg) is preferably 320°C or higher, more preferably 340°C or higher, and still more preferably 350°C or higher.

The total light transmittance is preferably 88% or more, more preferably 89% or more, and still more preferably 90% or more, when it is made into a film with a thickness of 10 μm. The yellowness index (YI) is preferably 2.9 or less, more preferably 2.7 or less, and still more preferably 2.5 or less, when a film having a thickness of 10 μm is formed. The coefficient of linear thermal expansion (CTE) is preferably 25 ppm/°C or lower, more preferably 20 ppm/°C or lower, and still more preferably 12 ppm/°C or lower with respect to the CTE of 100 to 250°C. The transmittance of light with a wavelength of 308 nm is preferably 1.0% or less, more preferably 0.6% or less, and still more preferably 0.4% or less, when a film with a thickness of 10 μm is formed. The smaller the light transmittance at the wavelength of 308 nm, the better the laser peeling property when peeled off by the XeCl excimer laser with the wavelength of 308 nm. In addition, the tensile elastic modulus, tensile strength, glass transition temperature (Tg), total light transmittance, yellow index (YI), coefficient of linear thermal expansion (CTE), and light transmittance at a wavelength of 308 nm in the present invention are specifically It can be measured by the method described in the Examples.

[Manufacturing method of polyimide resin] The polyimide resin of the present invention can be prepared by containing a compound providing the above-mentioned structural unit (A-1), a compound providing the above-mentioned structural unit (A-2), and a compound providing the above-mentioned structural unit (A-3). The tetracarboxylic acid component and the diamine component containing the compound which provides the said structural unit (B-1) are reacted, and it manufactures.

The compound represented by the formula (a-1) can be mentioned as the compound providing the structural unit (A-1), but it is not limited thereto, and a derivative thereof may also be used within the scope of providing the same structural unit. Examples of the derivatives include tetracarboxylic acids corresponding to the tetracarboxylic dianhydride represented by the formula (a-1) (that is, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2' '-norbornane-5,5'',6,6''-tetracarboxylic acid), and the alkyl ester of the tetracarboxylic acid. The compound providing the structural unit (A-1) is preferably a compound represented by the formula (a-1) (ie, dianhydride). Similarly, the compound represented by the formula (a-2) can be exemplified as the compound that provides the structural unit (A-2), but it is not limited thereto, and a derivative thereof may also be used within the scope of providing the same structural unit. Examples of the derivatives include tetracarboxylic acids corresponding to the tetracarboxylic dianhydride represented by the formula (a-2), and alkyl esters of the tetracarboxylic acids. The compound providing the structural unit (A-2) is preferably a compound represented by the formula (a-2) (ie, dianhydride). Similarly, the compound represented by the formula (a-3) is exemplified as the compound providing the structural unit (A-3), but it is not limited thereto, and a derivative thereof may also be used within the scope of providing the same structural unit. Examples of the derivatives include tetracarboxylic acids corresponding to the tetracarboxylic dianhydride represented by the formula (a-3), and alkyl esters of the tetracarboxylic acids. The compound providing the structural unit (A-3) is preferably a compound represented by the formula (a-3) (ie, dianhydride).

The compound represented by the formula (b-1) may be mentioned as the compound providing the structural unit (B-1), but it is not limited thereto, and a derivative thereof may be also provided within the scope of providing the same structural unit. Examples of the derivatives include diisocyanates corresponding to the diamines represented by the formula (b-1). The compound providing the structural unit (B-1) is preferably a compound represented by the formula (b-1) (ie, a diamine).

The content of the compound providing the constituent unit (A-1) in the tetracarboxylic acid component is preferably 10-80 mol %, more preferably 15-55 mol %, still more preferably 20-45 mol %, particularly preferably It is 22.5 to 40 mol%. The content of the compound providing the constituent unit (A-2) in the tetracarboxylic acid component is preferably 10-80 mol %, more preferably 20-60 mol %, still more preferably 25-50 mol %, particularly preferably It is 27.5 to 45 mol%. The content of the compound providing the constituent unit (A-3) in the tetracarboxylic acid component is preferably 10-80 mol %, more preferably 25-65 mol %, still more preferably 30-55 mol %, particularly preferably It is 32.5 to 50 mol%. The total content of the compound providing the structural unit (A-1), the compound providing the structural unit (A-2), and the compound providing the structural unit (A-3) in the tetracarboxylic acid component is preferably 50 mol% or more, More preferably, it is 70 mol % or more, still more preferably 90 mol % or more, and particularly preferably 99 mol % or more. The upper limit of the total content of the compound providing the structural unit (A-1), the compound providing the structural unit (A-2), and the compound providing the structural unit (A-3) is not particularly limited, that is, 100 mol %. The tetracarboxylic acid component may be composed of only the compound providing the structural unit (A-1), the compound providing the structural unit (A-2), and the compound providing the structural unit (A-3).

The tetracarboxylic acid component may contain a compound other than the compound providing any one of the structural units (A-1) to (A-3), and the above-mentioned aromatic tetracarboxylic dianhydride, lipid Cyclic tetracarboxylic dianhydride, aliphatic tetracarboxylic dianhydride, and derivatives thereof (tetracarboxylic acid, alkyl ester of tetracarboxylic acid, etc.). The compound arbitrarily contained in the tetracarboxylic acid component (that is, the compound other than the compound providing any one of the structural units (A-1) to (A-3)) may be one type or two or more types.

The content of the compound providing the constituent unit (B-1) in the diamine component is preferably 50 mol % or more, more preferably 70 mol % or more, more preferably 90 mol % or more, and particularly preferably 99 mol % %above. The upper limit value of the content of the compound providing the constituent unit (B-1) is not particularly limited, that is, 100 mol %. The diamine component may be composed of only the compound that provides the structural unit (B-1).

The diamine component may contain a compound other than the compound providing the structural unit (B-1), and the above-mentioned aromatic diamine, alicyclic diamine, and aliphatic diamine, and derivatives thereof can be exemplified as the compound. substances (diisocyanates, etc.). The compound arbitrarily contained in the diamine component (that is, the compound other than the compound which provides the structural unit (B-1)) may be one type or two or more types.

In terms of the addition ratio of the tetracarboxylic acid component and the diamine component used in the production of the polyimide resin of the present invention, the diamine component is preferably 0.9 to 1.1 mol relative to 1 mol of the tetracarboxylic acid component.

Moreover, when manufacturing the polyimide resin of this invention, in addition to the said tetracarboxylic-acid component and a diamine component, you may use a blocking agent. The end-capping agents are preferably monoamines or dicarboxylic acids. The amount of the terminal blocking agent to be introduced is preferably 0.0001 to 0.1 mol, more preferably 0.001 to 0.06 mol, relative to 1 mol of the tetracarboxylic acid component. For monoamine end-capping agents, for example, recommended: methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline, etc. Among these, benzylamine and aniline can be preferably used. The dicarboxylic acid-based end-capping agent is preferably a dicarboxylic acid, and a part of the end-capping agent may be closed. For example, recommended: phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenonedicarboxylic acid, 3,4-benzophenonedicarboxylic acid, cyclohexane-1, 2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, etc. Among these, phthalic acid and phthalic anhydride can be preferably used.

The method in particular of making the said tetracarboxylic-acid component and diamine component react is not restrict|limited, A well-known method can be used. Specific reaction methods include: (1) adding a tetracarboxylic acid component, a diamine component, and a reaction solvent to a reactor, stirring at room temperature to 80° C. for 0.5 to 30 hours, and then heating up and performing the reaction. The method of amination reaction; (2) after adding the diamine component and the reaction solvent into the reactor and making it dissolved, add the tetracarboxylic acid component, and stir at room temperature to 80 ° C for 0.5 to 30 hours as needed, and then heat up and A method of carrying out the imidization reaction, (3) a method of adding the tetracarboxylic acid component, the diamine component, and the reaction solvent to the reactor, and immediately raising the temperature to carry out the imidization reaction.

The reaction solvent used in the production of the polyimide resin may be any one that does not interfere with the imidization reaction and can dissolve the produced polyimide. For example, an aprotic solvent, a phenol type solvent, an ether type solvent, a carbonate type solvent, etc. are mentioned.

Specific examples of the aprotic solvent include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactamide, Amide-based solvents such as 1,3-dimethylimidazolidinone and tetramethylurea; lactone-based solvents such as γ-butyrolactone and γ-valerolactone; hexamethylphosphamide, hexamethylphosphine Phosphorus-containing amide-based solvents such as amide; sulfur-containing solvents such as dimethyl sulfoxide, dimethyl sulfoxide, and cyclobutane; ketone-based solvents such as acetone, cyclohexanone, and methylcyclohexanone; picoline , amine-based solvents such as pyridine; ester-based solvents such as acetic acid (2-methoxy-1-methylethyl ester), etc.

Specific examples of the phenolic solvent include: phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol -Xylenol, 3,4-Xylenol, 3,5-Xylenol, etc. Specific examples of the ether-based solvent include 1,2-dimethoxyethane, bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane, Bis[2-(2-methoxyethoxy)ethyl]ether, tetrahydrofuran, 1,4-dioxane, etc. Moreover, as a specific example of a carbonate-based solvent, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, etc. are mentioned. Among the above reaction solvents, an amide-based solvent or a lactone-based solvent is preferred. Moreover, the said reaction solvent may be used individually or in mixture of 2 or more types.

The imidization reaction is preferably carried out using a Dean-Stark apparatus or the like while removing water generated during production. By performing such an operation, the degree of polymerization and the imidization rate can be further improved.

In the above-mentioned imidization reaction, a known imidization catalyst can be used. As the imidization catalyst, an alkali catalyst or an acid catalyst can be mentioned. Examples of the base catalyst include: pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethyl Amine, tripropylamine, tributylamine, triethylenediamine, imidazole, N,N-dimethylaniline, N,N-diethylaniline and other organic base catalysts; potassium hydroxide, sodium hydroxide, potassium carbonate , sodium carbonate, potassium bicarbonate, sodium bicarbonate and other inorganic base catalysts. Moreover, as an acid catalyst, crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, toluic acid, hydroxybenzoic acid, terephthalic acid, benzenesulfonic acid, p-toluenesulfonic acid can be mentioned. , naphthalene sulfonic acid, etc. The above-mentioned imidization catalysts may be used alone or in combination of two or more. Among the above, from the viewpoint of operability, an alkali catalyst is preferably used, an organic alkali catalyst is more preferably used, triethylamine is more preferably used, and triethylamine and triethylenediamine are particularly preferably used in combination.

The temperature of the imidization reaction is preferably 120 to 250°C, more preferably 160 to 200°C, in consideration of the reaction rate and the inhibition of gelation. In addition, the reaction time is preferably 0.5 to 10 hours from the start of distillation of the produced water.

[Polyimide Varnish] The polyimide varnish of the present invention is obtained by dissolving the polyimide resin of the present invention in an organic solvent. That is, the polyimide varnish of the present invention contains the polyimide resin of the present invention and an organic solvent, and the polyimide resin is soluble in the organic solvent. The organic solvent is not particularly limited as long as it dissolves the polyimide resin, and the above-mentioned compounds as the reaction solvent used in preparing the polyimide resin are preferably used alone or in combination of two or more. The polyimide varnish of the present invention may be a polyimide solution itself obtained by dissolving a polyimide resin obtained by a polymerization method in a reaction solvent, or may be a polyimide solution that is further diluted with a solvent. adult.

The polyimide resin of the present invention has solvent solubility, so it can be made into a stable high-concentration varnish at room temperature. The content of the polyimide resin of the present invention in the polyimide varnish of the present invention is preferably 5 to 40% by mass, more preferably 10 to 30% by mass. The viscosity of the polyimide varnish is preferably 1-200Pa･s, more preferably 5-150Pa･s. The viscosity of the polyimide varnish is a value measured at 25°C using an E-type viscometer. In addition, the polyimide varnish of the present invention may also contain inorganic fillers, adhesion promoters, release agents, flame retardants, UV stabilizers, interface Activating agent, leveling agent, defoaming agent, optical brightener, cross-linking agent, polymerization initiator, sensitizer and other additives. The manufacturing method of the polyimide varnish of this invention is not specifically limited, A well-known method can be used.

[Polyimide film] The polyimide film of the present invention contains the polyimide resin of the present invention. Therefore, the polyimide film of the present invention has good mechanical properties and heat resistance, and is excellent in colorless transparency, dimensional stability to heat, laser peelability and organic solvent resistance. The desirable physical properties of the polyimide film of the present invention are as described above. The manufacturing method of the polyimide film of this invention is not specifically limited, A well-known method can be used. For example, after coating the polyimide varnish of the present invention on a smooth support such as a glass plate, metal plate, plastic, etc., or forming it into a film, removing the reaction solvent contained in the varnish by heating, diluting Methods of organic solvents such as solvents, etc. A release agent can also be pre-coated on the surface of the aforementioned support if necessary. The method for removing the organic solvent contained in the varnish by heating is preferably the following method. That is, after evaporating the organic solvent at a temperature below 120°C and making a self-supporting film, the self-supporting film is peeled off from the support, the end of the self-supporting film is fixed, and the organic solvent is used. The temperature above the boiling point is dried to produce a polyimide film. In addition, drying is preferably performed in a nitrogen atmosphere. The pressure of the drying environment can be any one of reduced pressure, normal pressure, and increased pressure. The heating temperature at the time of drying the self-supporting film to manufacture the polyimide film is preferably 320°C or higher, more preferably 340°C or higher, from the viewpoint of imparting organic solvent resistance to the polyimide film. The upper limit of the heating temperature is not particularly limited, but it is preferably 400°C or lower.

The thickness of the polyimide film of the present invention can be appropriately selected according to the application and the like, and is preferably in the range of 1 to 250 μm, more preferably 5 to 100 μm, and still more preferably 10 to 80 μm. With a thickness of 1 to 250 μm, it can be practically used as a self-supporting film. The thickness of the polyimide film can be easily controlled by adjusting the solid content concentration and viscosity of the polyimide varnish.

The polyimide film of the present invention can be suitably used as a film for various members such as color filters, flexible displays, semiconductor parts, and optical members. In particular, the polyimide film of the present invention can be ideally used as a substrate for image display devices such as liquid crystal displays and OLED displays. [Example]

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these embodiments. The solid content concentration of the polyimide varnishes obtained in Examples and Comparative Examples and the physical properties of the polyimide films were measured by the methods shown below.

(1) Solid content concentration The determination of the solid content concentration of polyimide varnish is to use the small electric furnace "MMF-1" manufactured by AS ONE Co., Ltd. to heat the sample at 320°C × 120min, and determine the mass of the sample before and after heating. The difference is calculated. (2) Film thickness The film thickness was measured using a micrometer manufactured by Mitutoyo Co., Ltd. (3) Tensile strength, tensile modulus of elasticity The measurement was performed using a tensile testing machine "Strograph VG-1E" manufactured by Toyo Seiki Co., Ltd. in accordance with JIS K7127. (4) Glass transition temperature (Tg) Using a thermomechanical analyzer "TMA/SS6100" manufactured by Hitachi High-Tech Science Co., Ltd., the temperature was raised to Tg under the conditions of a sample size of 2 mm × 20 mm, a load of 0.1 N, and a heating rate of 10°C/min in the tensile mode. After the residual stress was removed as described above, Tg was determined by performing TMA measurement from 50°C to 400°C under the same conditions. (5) Total light transmittance, yellow index (YI) According to JIS K7361-1, the measurement was performed using a color-turbidity simultaneous measuring device "COH400" manufactured by Nippon Denshoku Industries Co., Ltd. (6) Coefficient of Linear Thermal Expansion (CTE) Using a thermomechanical analyzer "TMA/SS6100" manufactured by Hitachi High-Tech Science Co., Ltd., TMA measurement was performed in the tensile mode under the conditions of a sample size of 2 mm × 20 mm, a load of 0.1 N, and a heating rate of 10°C/min. , find the CTE of 100～250℃. (7) Light transmittance at wavelength 308nm The measurement was performed using an ultraviolet-visible-near-infrared spectrophotometer "UV-3100PC" manufactured by Shimadzu Corporation. (8) Organic solvent resistance The obtained thin film was immersed in an organic solvent for a predetermined time, and the organic solvent resistance was evaluated. In addition, as the organic solvent, a mixed solvent (mixed at a mass ratio of 1:1) of N-methyl-2-pyrrolidone (NMP) and 2-aminoethanol, which is a stripping solution for removing the photoresist layer, was used. The evaluation criteria of the organic solvent resistance are set as follows. E: The film surface was dissolved when immersed in an organic solvent for less than 10 minutes. D: The film surface is dissolved when immersed in an organic solvent for 10 minutes or more and less than 20 minutes. C: When immersed in an organic solvent for 20 minutes or more and less than 30 minutes, the film surface is dissolved. B: The film surface was dissolved when immersed in an organic solvent for 30 minutes or more and less than 40 minutes. A: After immersion in an organic solvent for 40 minutes, the film surface was not dissolved and unchanged. From a practical point of view, it is preferable that the film surface does not dissolve and does not change for 10 minutes or more, and the above-mentioned evaluation E is a level that is unacceptable.

The acid dianhydrides and diamines used in Examples and Comparative Examples, and their abbreviations are as follows. <Acid dianhydride> CpODA: norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride (JX Energy ( stock) company system; compound represented by formula (a-1)) BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride (manufactured by Mitsubishi Chemical Corporation; compound represented by formula (a-2)) HPMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi Gas Chemical Co., Ltd.; compound represented by formula (a-3)) ＜Diamine＞ TFMB: 2,2'-bis(trifluoromethyl)benzidine (manufactured by Wakayama Seika Industry Co., Ltd.; compound represented by formula (b-1))

<Example 1> TFMB 32.024 g (0.100 mol), TFMB 32.024 g (0.100 mol), TFMB 32.024 g (0.100 mol), TFMB was placed in a 1-L, 5-neck round-bottomed flask equipped with a half-moon-shaped stirring blade made of stainless steel, a nitrogen introduction tube, a Dean-Stark apparatus equipped with a cooling tube, a thermometer, and a glass end cap. and γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) 73.799 g, and stirred at a rotation speed of 200 rpm at a temperature of 70° C. in the system under a nitrogen atmosphere to obtain a solution. To this solution, 11.531 g (0.030 mol) of CpODA, 8.826 g (0.030 mol) of BPDA, 8.967 g (0.040 mol) of HPMDA, and 18.450 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added at one time. After that, 5.06 g of triethylamine (manufactured by Kanto Chemical Co., Ltd.) and 0.056 g of triethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) were added as imidization catalysts, and heated with a heating mantle, The temperature in the reaction system was raised to 190°C over about 20 minutes. The internal temperature of the reaction system was maintained at 190° C. and refluxed for 5 hours while collecting the distilled components and adjusting the rotational speed according to the increase in viscosity. Then, 164.99 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) was added, and the temperature in the reaction system was cooled to 120° C., followed by further stirring for about 3 hours to make it uniform to obtain a polyamide having a solid content concentration of 10% by mass. Imine varnish. Then, the obtained polyimide varnish was coated on a glass plate, kept at 80°C for 20 minutes on a hot plate, and then heated at 350°C for 30 minutes in a nitrogen atmosphere in a hot air dryer to evaporate the solvent to obtain a thickness of 10μm thin film. The results are shown in Table 1.

<Example 2> A polyimide varnish was prepared in the same manner as in Example 1, except that the amount of CpODA was changed from 0.030 mol to 0.025 mol, and the amount of BPDA was changed from 0.030 mol to 0.035 mol to obtain a solid content Polyimide varnish with a concentration of 10% by mass. Using the obtained polyimide varnish, a thin film was produced in the same manner as in Example 1 to obtain a thin film having a thickness of 20 μm. The results are shown in Table 1.

<Example 3> A polyimide varnish was prepared in the same manner as in Example 1, except that the amount of BPDA was changed from 0.030 mol to 0.035 mol, and the amount of HPMDA was changed from 0.040 mol to 0.035 mol to obtain a solid content Polyimide varnish with a concentration of 10% by mass. Using the obtained polyimide varnish, a thin film was produced in the same manner as in Example 1 to obtain a thin film having a thickness of 14 μm. The results are shown in Table 1.

<Comparative Example 1> A polyimide varnish was produced in the same manner as in Example 1, except that only 0.100 mol of CpODA was used for the acid dianhydride, and a polyimide varnish having a solid content concentration of 10% by mass was obtained. Using the obtained polyimide varnish, a thin film was produced in the same manner as in Example 1 to obtain a thin film having a thickness of 14 μm. The results are shown in Table 1.

<Comparative Example 2> TFMB32.024g (0.100mol), TFMB32.024g (0.100mol), TFMB32.024g (0.100mol) was placed in a 500mL 5-neck round-bottom flask equipped with a stainless steel half-moon-shaped stirring blade, a nitrogen introduction tube, a Dean-Stark apparatus equipped with a cooling tube, a thermometer, and a glass end cap. and 73.993 g of N,N-dimethylformamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.), the solution was stirred at a rotation speed of 200 rpm at a temperature of 50° C. in the system and a nitrogen atmosphere. To this solution, 29.420 g (0.100 mol) of BPDA and 18.498 g of N,N-dimethylformamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) were added at one time, and dissolved in about 20 minutes. When the viscosity increased, the rotational speed was adjusted, and the mixture was stirred at room temperature for 5 hours. Then, 165.442 g of N,N- dimethylformamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was added, and the mixture was stirred for about 1 hour to make it uniform to obtain a polyamide varnish having a solid content concentration of 20% by mass. Then, the obtained polyamide varnish was coated on a glass plate, kept at 80° C. for 20 minutes on a hot plate, and then heated at 350° C. for 30 minutes in a hot air dryer in a nitrogen atmosphere to make the polyamide The amino acid was imidized, and the solvent in the varnish was evaporated to obtain a film with a thickness of 7 μm. The results are shown in Table 1.

<Comparative Example 3> A polyimide varnish was produced in the same manner as in Example 1, except that only 0.100 mol of HPMDA was used for the acid dianhydride, and a polyimide varnish having a solid content concentration of 10% by mass was obtained. Using the obtained polyimide varnish, a thin film was produced in the same manner as in Example 1, and a thin film having a thickness of 10 μm was obtained. The results are shown in Table 1.

【Table 1】

As shown in Table 1, the polyimide films of Examples 1 to 3 had good mechanical properties and heat resistance, and were excellent in colorless transparency, dimensional stability to heat, laser peelability, and organic solvent resistance. On the other hand, the polyimide film of Comparative Example 1 had very poor laser peelability, and the organic solvent resistance was also at a practically unacceptable level. The polyimide film of Comparative Example 2 is slightly less colorless and transparent, and has very poor dimensional stability to heat. The polyimide film of Comparative Example 3 has very poor thermal dimensional stability and laser peelability.

Claims (4)

A polyimide resin having a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, the structural unit A containing a structural unit (A-1) derived from a compound represented by the following formula (a-1) ), a structural unit (A-2) derived from a compound represented by the following formula (a-2), and a structural unit (A-3) derived from a compound represented by the following formula (a-3), the structural unit B containing the following The ratio of the constituent unit (B-1) of the compound represented by the formula (b-1) to the constituent unit A of the constituent unit (A-3) is 35 to 80 mol %, and the constituent unit (B-1) is in the The ratio in the constituent unit B is 50 mol % or more;

Such as the polyimide resin of claim 1, wherein the ratio of the structural unit (A-1) in the structural unit A is 10 to 55 mol %, The ratio of the structural unit (A-2) in the structural unit A is 10 to 50 mol %. A polyimide varnish is prepared by dissolving the polyimide resin as claimed in item 1 or 2 of the patented scope in an organic solvent. A polyimide film containing the polyimide resin as claimed in item 1 or 2 of the patented scope.