JP6060695B2 - Polyimide precursor and polyimide - Google Patents

Description

  The present invention relates to a polyimide having excellent characteristics such as transparency, bending resistance, and high heat resistance, and also having a very low coefficient of thermal expansion and solvent resistance, and a precursor thereof.

  In recent years, with the advent of advanced information society, development of optical materials such as liquid crystal alignment films and protective films for color filters in the field of display devices, such as optical fibers and optical waveguides in the field of optical communication, has been progressing. As a substitute for the glass substrate, a lightweight and flexible plastic substrate has been studied, and a display that can be bent and rolled has been actively developed. For this reason, higher performance optical materials that can be used for such applications are demanded.

  Aromatic polyimide is essentially yellowish brown due to intramolecular conjugation and the formation of charge transfer complexes. For this reason, as a means to suppress coloration, for example, introduction of fluorine atoms into the molecule, imparting flexibility to the main chain, introduction of bulky groups as side chains, etc. inhibits intramolecular conjugation and charge transfer complex formation. Thus, a method for expressing transparency has been proposed. In addition, a method for expressing transparency by using a semi-alicyclic or fully alicyclic polyimide that does not form a charge transfer complex in principle has been proposed.

In Patent Document 1, in order to obtain a thin, light, and hard-to-break active matrix display device, a normal film forming process is used on a transparent polyimide film substrate in which a tetracarboxylic acid component residue is an aliphatic group. It is disclosed that a thin film transistor is formed to obtain a thin film transistor substrate. The polyimide specifically used here was prepared from 1,2,4,5-cyclohexanetetracarboxylic dianhydride as the tetracarboxylic acid component and 4,4′-diaminodiphenyl ether as the diamine component. Is.
Patent Document 2 discloses a colorless transparent resin film made of polyimide that is excellent in colorless transparency, heat resistance, and flatness, which is used for transparent substrates, thin film transistor substrates, flexible wiring substrates, and the like of liquid crystal display elements and organic EL display elements. A production method obtained by a solution casting method using a specific drying step is disclosed. The polyimide used here is composed of 1,2,4,5-cyclohexanetetracarboxylic dianhydride as a tetracarboxylic acid component and α, α′-bis (4-aminophenyl) -1, a diamine component. And those prepared from 4-diisopropylbenzene and 4,4′-bis (4-aminophenoxy) biphenyl.

Such a semi-alicyclic polyimide using an alicyclic tetracarboxylic dianhydride as a tetracarboxylic acid component and an aromatic diamine as a diamine component has both transparency, bending resistance and high heat resistance. However, since such a semi-alicyclic polyimide generally has a large coefficient of thermal expansion of 50 ppm / K or more, the difference in coefficient of thermal expansion from a conductor such as metal is large, and warping occurs when a circuit board is formed. In some cases, a problem such as an increase in the size of the circuit may occur, and in particular, there is a problem that a fine circuit forming process such as a display application is not easy.
Furthermore, such semi-alicyclic polyimides tend to have insufficient solvent resistance, which may cause problems in the circuit formation process.

JP 2003-168800 A International Publication No. 2008/146737

  The present invention has been made in view of the above situation, and in the semi-alicyclic polyimide using an alicyclic tetracarboxylic dianhydride as a tetracarboxylic acid component and an aromatic diamine as a diamine component, The purpose is to improve the expansion coefficient and solvent resistance.

  That is, an object of the present invention is to provide a polyimide precursor and a polyimide that have excellent characteristics such as transparency, bending resistance, and high heat resistance, and also have extremely low thermal linear expansion coefficient and solvent resistance. . Since this polyimide precursor and polyimide have a low coefficient of linear expansion and high solvent resistance that facilitates the formation of fine circuits, they should be used suitably to form substrates for display applications. Can do.

The present invention relates to the following items.
1. The polyimide precursor characterized by including the repeating unit represented by following Chemical formula (1).

(In the formula, A is a tetravalent group having at least one aliphatic 6-membered ring in the chemical structure and no aromatic ring, and B is at least one ester bond and aromatic group in the chemical structure. And each of X ₁ and X ₂ is independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.)

2. Item 2. A polyimide precursor according to Item 1, wherein A is a tetravalent group selected from the group consisting of the following chemical formulas (2) to (5).

(In the formula, R 1 is a direct bond, a CH ₂ group, a C (CH ₃ ) ₂ group, a SO ₂ group, a Si (CH ₃ ) ₂ group, a C (CF ₃ ) ₂ group, an oxygen atom, or a sulfur atom. )

(In the formula, R 2 represents a CH ₂ group, a C ₂ H ₄ group, an oxygen atom, or a sulfur atom.)

(In the formula, R 3 and R 4 are each independently a CH ₂ group, a CH ₂ CH ₂ group, an oxygen atom, or a sulfur atom.)

3. Item 3. The polyimide precursor according to Item 1 or 2, wherein B is one or more selected from the group consisting of the following chemical formulas (6) to (8).

(In the formula, Ar ₁ , Ar ₂ and Ar ₃ are each independently a divalent group having an aromatic ring having 6 to 18 carbon atoms, and n 1 is an integer of 0 to 5).

(In the formula, Ar ₄ , Ar ₅ , Ar ₆ , Ar ₇ and Ar ₈ are each independently a divalent group having an aromatic ring having 6 to 18 carbon atoms, and n2 is 0 to 5) (It is an integer.)

(In the formula, Ar ₉ , Ar ₁₀ , Ar ₁₁ , Ar ₁₂ , Ar ₁₃ are each independently a divalent group having an aromatic ring having 6 to 18 carbon atoms, and n3 is 0 to 5 (It is an integer.)

4). A tetracarboxylic acid component containing 70 mol% or more of a tetracarboxylic acid component giving a repeating unit represented by the chemical formula (1) and 30 mol% or less of the other tetracarboxylic acid component in 100 mol% of all tetracarboxylic acid components And a diamine component containing 70 mol% or more of a diamine component giving a repeating unit represented by the chemical formula (1) and 30 mol% or less of other diamine components in 100 mol% of all diamine components. Item 4. The polyimide precursor according to any one of Items 1 to 3.

5. The logarithmic viscosity (temperature: 30 ° C., concentration: 0.5 g / dL, solvent: N, N-dimethylacetamide) of the polyimide precursor according to any one of Items 1 to 4 is 0.2 dL / g or more. A polyimide precursor solution composition characterized by the above.

6). The polyimide characterized by including the repeating unit represented by following Chemical formula (9).

(In the formula, A is a tetravalent group having at least one aliphatic 6-membered ring in the chemical structure and no aromatic ring, and B is at least one ester bond and aromatic group in the chemical structure. A divalent group having a group ring.)

7). A polyimide film obtained by using the polyimide precursor solution composition according to Item 5 or the polyimide film according to Item 6.

8). A substrate for a display, a touch panel, or a solar cell, which is formed using the polyimide obtained by using the polyimide precursor solution composition according to Item 5 or the polyimide according to Item 6.

  According to the present invention, it is possible to provide a polyimide precursor and a polyimide that have excellent properties such as transparency, bending resistance, and high heat resistance, and further have extremely low thermal linear expansion coefficient and solvent resistance. Since this polyimide precursor and polyimide have a low coefficient of linear expansion and high solvent resistance that facilitates the formation of fine circuits, they should be used suitably to form substrates for display applications. Can do. Moreover, the polyimide of this invention can be used suitably also in order to form the board | substrate for touch panels and a solar cell.

The polyimide precursor of this invention is a polyimide precursor comprised including the repeating unit represented by the said Chemical formula (1).
In other words, the polyimide precursor of the present invention comprises an alicyclic tetracarboxylic acid component having at least one aliphatic 6-membered ring in the chemical structure and no aromatic ring, and at least one in the chemical structure. It is a semi-alicyclic polyimide precursor obtained from an aromatic diamine component having an ester bond and an aromatic ring.
The polyimide precursor of the present invention may be a polyimide precursor obtained by using other tetracarboxylic acid components and / or diamine components. For example, in 100 mol% of all tetracarboxylic acid components, the chemical formula (1) 70 mol% or more of a tetracarboxylic acid component (that is, an alicyclic tetracarboxylic acid component having at least one aliphatic 6-membered ring and no aromatic ring in the chemical structure) that gives a repeating unit represented by A tetracarboxylic acid component containing 30 mol% or less of the other tetracarboxylic acid component, and a diamine component giving a repeating unit represented by the chemical formula (1) in 100 mol% of all diamine components (that is, in the chemical structure) An aromatic diamine component having at least one amide bond and an aromatic ring) at 70 mol% or more, and other diamine components at 30 mol% or less. A polyimide precursor obtained from the no-diamine component may be.

The tetracarboxylic acid component used in the present invention is an alicyclic tetracarboxylic acid component that has at least one aliphatic 6-membered ring in its chemical structure and does not have an aromatic ring, and is a 6-membered component in the tetracarboxylic acid component. There may be a plurality of rings, and a plurality of 6-membered rings may be composed of two or more common carbon atoms. Further, the 6-membered ring may be a bridged ring type in which carbon atoms constituting the ring (inside the 6-membered ring) further form a ring by a chemical bond.
A tetracarboxylic acid component having a six-membered ring structure that is not asymmetrical and highly symmetric is preferable because it enables high-density packing of polymer chains and is excellent in solvent resistance, heat resistance, and mechanical strength of polyimide. . Furthermore, the tetracarboxylic acid component is a polyalicyclic type in which a plurality of 6-membered rings are constituted by two or more common carbon atoms, and the carbon atoms in which the 6-membered rings form a ring further form a ring by a chemical bond. The formed crosslinked ring type is more preferable because good heat resistance, solvent resistance and low thermal linear expansion property of polyimide can be easily achieved.

  As the tetravalent group derived from the tetracarboxylic acid component represented by A in the chemical formula (1), for example, the groups of the chemical formulas (2) to (5) are preferable, and the chemical formula (4) or (5) ) Is more preferable, and the group of the chemical formula (5) is particularly preferable. Compared to the groups represented by the chemical formulas (2) and (3), the groups represented by the chemical formulas (4) and (5) are more preferable because they have a crosslinked ring type and are excellent in heat resistance of the polyimide and have a small coefficient of thermal linear expansion. . Furthermore, since the group of the chemical formula (5) is a polyalicyclic ring / crosslinked ring type, it is particularly preferable because it has more excellent heat resistance of polyimide.

Examples of the tetracarboxylic acid component that introduces the chemical structure represented by the chemical formula (2) or (3) include cyclohexane-1,2,4,5-tetracarboxylic acid and [1,1′-bi (cyclohexane)]-3. , 3 ′, 4,4′-tetracarboxylic acid, [1,1′-bi (cyclohexane)]-2,3,3 ′, 4′-tetracarboxylic acid, [1,1′-bi (cyclohexane)] -2,2 ', 3,3'-tetracarboxylic acid, 4,4'-methylenebis (cyclohexane-1,2-dicarboxylic acid), 4,4'-(propane-2,2-diyl) bis (cyclohexane-) 1,2-dicarboxylic acid), 4,4′-oxybis (cyclohexane-1,2-dicarboxylic acid), 4,4′-thiobis (cyclohexane-1,2-dicarboxylic acid), 4,4′-sulfonylbis ( Cyclohexane-1,2-dicarboxylic acid), 4 Derivatives such as 4 ′-(dimethylsilanediyl) bis (cyclohexane-1,2-dicarboxylic acid), 4,4 ′-(tetrafluoropropane-2,2-diyl) bis (cyclohexane-1,2-dicarboxylic acid) And these acid dianhydrides.
Among these, cyclohexane-1,2,4,5-tetracarboxylic acid, [1,1′-bi (cyclohexane)]-3,3 ′, 4,4′-tetracarboxylic acid, [1,1 ′ -Bi (cyclohexane)]-2,3,3 ', 4'-tetracarboxylic acid, [1,1'-bi (cyclohexane)]-2,2', 3,3'-tetracarboxylic acid derivatives and these The acid dianhydride is preferable because of its excellent solvent resistance and mechanical strength.
These tetracarboxylic acid components are not particularly limited, however, by performing separation and purification, the ratio of specific stereoisomers is 80% or more, more preferably 90% or more, and particularly preferably 95% or more. Improves the heat resistance and solvent resistance. Specific stereoisomers of such tetracarboxylic acid components include
1R, 2S, 4S, 5R-cyclohexanetetracarboxylic acid (hereinafter sometimes abbreviated as PMTA-HS, and its acid dianhydride may be abbreviated as PMDA-HS).
1S, 2S, 4R, 5R-cyclohexanetetracarboxylic acid (hereinafter sometimes abbreviated as PMTA-HH, and its acid dianhydride may be abbreviated as PMDA-HH),
(1R, 1 ′S, 3R, 3 ′S, 4R, 4 ′S) dicyclohexyl-3,3 ′, 4,4′-tetracarboxylic acid (hereinafter sometimes abbreviated as trans-DCTA), and its acid dianhydride Things may be abbreviated as trans-DCDA).
(1R, 1 ′S, 3R, 3 ′S, 4S, 4′R) dicyclohexyl-3,3 ′, 4,4′-tetracarboxylic acid (hereinafter sometimes abbreviated as cis-DCTA, and its acid dianhydride) The product may be abbreviated as cis-DCDA.)
PMTA-HS, trans-DCTA, and cis-DCTA are more preferable because of excellent reactivity when used as an acid dianhydride.

Examples of the polyalicyclic type or bridged ring type tetracarboxylic acid component that introduces the chemical structure of the chemical formula (4) or (5) include octahydropentalene-1,3,4,6-tetracarboxylic acid, bicyclo [2.2.1] Heptane-2,3,5,6-tetracarboxylic acid, 6- (carboxymethyl) bicyclo [2.2.1] heptane-2,3,5-tricarboxylic acid, bicyclo [2. 2.2] octane-2,3,5,6-tetracarboxylic acid, bicyclo [2.2.2] oct-5-ene-2,3,7,8-tetracarboxylic acid, tricyclo [4.2. 2.02,5] decane-3,4,7,8-tetracarboxylic acid, tricyclo [4.2.2.02,5] dec-7-ene-3,4,9,10-tetracarboxylic acid, 9-oxatricyclo [4.2.1.02,5] nonane-3,4,7,8-teto Carboxylic acid, decahydro-1,4: 5,8-dimethanol naphthalene 2,3,6,7 derivatives and their acid dianhydrides such as tetracarboxylic acid. Among these, bicyclo [2.2.1] heptane-2,3,5,6-tetracarboxylic acid, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic acid, decahydro Derivatives such as -1,4: 5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic acid and their acid dianhydrides are easy to produce, and the resulting polyimide has excellent heat resistance. Therefore, it is more preferable.
Although these tetracarboxylic acid components are not particularly limited, polyimide is obtained by performing separation and purification, etc., and setting the ratio of specific stereoisomers to 70% or more, more preferably 90% or more, and particularly preferably 95% or more. Can be reduced in thermal expansion. Specific stereoisomers of such tetracarboxylic acid components include
1rC7-bicyclo [2.2.2] octane-2t, 3t, 5c, 6c-tetracarboxylic acid (hereinafter sometimes abbreviated as cis / trans-BTTA-H, and the acid dianhydride is further referred to as cis / trans-BTA). (May be abbreviated as -H)
1rC7-bicyclo [2.2.2] octane-2c, 3c, 5c, 6c-tetracarboxylic acid (hereinafter sometimes abbreviated as cis / cis-BTTA-H, and the acid dianhydride is further referred to as cis / cis-BTA). (May be abbreviated as -H)
(4arH, 8acH) -decahydro-1t, 4t: 5c, 8c-dimethanonaphthalene-2t, 3t, 6c, 7c-tetracarboxylic acid (hereinafter sometimes abbreviated as DNTAxx, and the acid dianhydride is further abbreviated as DNDAxx. Sometimes.)
Is preferred.

  The structural formula of 1R, 2S, 4S, 5R-cyclohexanetetracarboxylic dianhydride (PMDA-HS) is shown below.

  The structural formula of 1rC7-bicyclo [2.2.2] octane-2c, 3c, 5c, 6c-tetracarboxylic dianhydride (cis / cis-BTA-H) is shown below.

  The structural formula of (4arH, 8acH) -decahydro-1t, 4t: 5c, 8c-dimethanonaphthalene-2t, 3t, 6c, 7c-tetracarboxylic dianhydride (DNDAxx) is shown below.

The tetracarboxylic acid component may be a single tetracarboxylic acid component as described above, or may be used in combination of two or more.
In addition, other aromatic or aliphatic tetracarboxylic acid components generally used in polyimide are used in a small amount (preferably 30 mol% or less, more preferably 10 mol%) within the range in which the characteristics of the polyimide of the present invention can be expressed. Hereinafter, more preferably less than 10 mol%) can be used in combination.
Other aromatic or aliphatic tetracarboxylic acid components that can be used in the present invention include, for example, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane, 4- (2,5-dioxy). Oxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid, pyromellitic acid, benzophenonetetracarboxylic acid, biphenyltetracarboxylic acid, oxydiphthalic acid, biscarboxyphenyldimethylsilane, bis Examples thereof include derivatives such as dicarboxyphenoxydiphenyl sulfide, sulfonyldiphthalic acid, cyclobutanetetracarboxylic acid, isopropylidenediphenoxybisphthalic acid, and acid dianhydrides thereof.

The tetracarboxylic acid component used in the present invention is not particularly limited, but purity (in the case of using a plurality of types of tetracarboxylic acid components, the value of the highest purity tetracarboxylic acid component or all of the tetracarboxylic acid components used) The value of the mixture) is preferably 90% or more, preferably 98% or more, more preferably 99% or more. If the purity is less than 90%, the molecular weight of the polyimide precursor is not sufficient, and the resulting polyimide may have poor heat resistance.
The purity is a value obtained from gas chromatography analysis or ¹ H-NMR analysis. In the case of tetracarboxylic dianhydride, the purity can be obtained as a tetracarboxylic acid by performing a hydrolysis treatment.

  Further, the tetracarboxylic acid component used in the present invention is not particularly limited, but the light transmittance (in the case of using a plurality of types of tetracarboxylic acid components, the value of the tetracarboxylic acid component having the best light transmittance or all of the used values. The value of the mixture of tetracarboxylic acid components) is 70% or more, preferably 80% or more, more preferably 90% or more. However, the light transmittance here is a transmittance of a wavelength of 400 nm and an optical path length of 1 cm with respect to a solution obtained by dissolving in a 2N sodium hydroxide solution at a concentration of 10% by mass. When the light transmittance of the tetracarboxylic acid component is 70% or more, coloring of the resulting polyimide is reduced, which is favorable.

In the present invention, the diamine component is a diamine component having at least one ester bond and an aromatic ring in the chemical structure.
In the polyimide precursor of the present invention, an ester bond is introduced into the chemical structure by the diamine component. A polyimide obtained from a polyimide precursor having an ester bond introduced is thought to have improved thermal linear expansion coefficient, solvent resistance, and the like because intermolecular interaction is increased by the ester bond. Therefore, the diamine component preferably has one or more ester bonds, preferably a plurality of ester bonds, in the chemical structure. In addition, when there are too many ester bonds in a diamine component, the solubility of a polyimide precursor may fall.
As the divalent group derived from the diamine component represented by B in the chemical formula (1), for example, the groups of the chemical formulas (6) to (8) are preferable.

Ar _{1 to} Ar ₁₃ in the chemical formulas (6) to (8) are each independently a divalent group having an aromatic ring having 6 to 18 carbon atoms. The aromatic ring here is, for example, a divalent aromatic compound such as benzene, biphenyl, terphenyl, naphthalene, anthracene, and a part of the hydrogen is an alkyl group having 1 to 3 carbon atoms, a halogen group, or a nitro group. It may be substituted with a group, a hydroxyl group, a carboxylic acid group or the like. As the divalent aromatic compound, benzene and biphenyl are preferable since the light transmittance of polyimide is excellent. Although not particularly limited, the bonding position of the divalent aromatic compound (bonding position forming the polyimide main chain) is para-position in benzene, biphenylene and terphenyl, and is 2,6-position in naphthalene and anthracene. Is preferable because the coefficient of thermal expansion of polyimide can be lowered.

  Examples of the diamine component that introduces the chemical structures of the chemical formulas (6) to (8) include 4-aminophenyl-4-aminobenzoate, 4-amino-3-chlorophenyl-4-aminobenzoate, and 4-amino-2- Chlorophenyl-4-aminobenzoate, 4-amino-2,6-dichlorophenyl-4-aminobenzoate, 4-amino-3-methylphenyl-4-aminobenzoate, 4-amino-2-methylphenyl-4-aminobenzoate, 4-amino-2,6-methylphenyl-4-aminobenzoate, 4-amino-3- (trifluoromethyl) phenyl-4-aminobenzoate, 4-amino-2- (trifluoromethyl) phenyl-4-amino Benzoate, 4-aminophenyl-4-amino-3-chlorobenzoate, 4- Minophenyl-4-amino-3-bromobenzoate, 4′-aminophenyl-4-amino-3-methylbenzoate, 4-aminophenyl-4-amino-2-chlorobenzoate, 4-aminophenyl-4-amino-2 -Bromobenzoate, 4-aminophenyl-4-amino-2-methylbenzoate, 3-aminophenyl-4-aminobenzoate, 3-amino-4- (trifluoromethyl) phenyl-4-aminobenzoate, 3-amino- 4-chlorophenyl-4-aminobenzoate, 3-amino-4-bromophenyl-4-aminobenzoate, 4-aminophenyl-3-aminobenzoate, 4-aminophenyl-3-amino-4-chlorobenzoate, 4-amino Phenyl-3-amino-4-methylbenzoate, bis 4-aminophenyl) terephthalate, bis (4-aminophenyl) -2,5-dichloroterephthalate, bis (4-aminophenyl) -2,5-dimethylterephthalate, bis (4-aminophenyl) -2,3,5 , 6-tetrafluoroterephthalate, bis (4-aminophenyl) -2,3,5,6-tetrachloroterephthalate, bis (4-aminophenyl) -2,3,5,6-tetrabromoterephthalate, bis (4 -Aminophenyl) -4-bromoisophthalate, bis (4-aminophenyl) -5-tert-butylisophthalate, bis (4-aminophenyl)-[1,1'-biphenyl] -4,4'-di Carboxylate, bis (4-aminophenyl) -2,2′-dichloro- [1,1′-biphenyl] -4,4′-dicarboxylate, bis (4-a Nophenyl) -2,5-dimethyl- [1,1′-biphenyl] -4,4′-dicarboxylate, bis (4-aminophenyl) -2,3,5,6-tetrafluoro- [1,1 '-Biphenyl] -4,4'-dicarboxylate, bis (4-aminophenyl) -2,3,5,6-tetrachloro- [1,1'-biphenyl] -4,4'-dicarboxylate Bis (4-aminophenyl) -2,3,5,6-tetrabromo- [1,1′-biphenyl] -4,4′-dicarboxylate, p-phenylenebis (p-aminobenzoate), m- Examples thereof include phenylene bis (p-aminobenzoate), [1,1′-biphenyl] -4,4′-diyl bis (4-aminobenzoate), and derivatives thereof. Of these, 4'-aminophenyl-4-aminobenzoate, bis (4-aminophenyl) terephthalate, p-phenylenebis (p-aminobenzoate), bis (4-aminophenyl)-[1,1'-biphenyl ] -4,4′-dicarboxylate, [1,1′-biphenyl] -4,4′-diyl bis (4-aminobenzoate) is preferred, bis (4-aminophenyl)-[1,1′- Biphenyl] -4,4′-dicarboxylate and [1,1′-biphenyl] -4,4′-diyl bis (4-aminobenzoate) are more preferred.

  The structural formula of bis (4-aminophenyl)-[1,1′-biphenyl] -4,4′-dicarboxylate (APBP) is shown below.

As the diamine component, the diamine components as described above may be used alone, or a plurality of types may be used in combination.
In addition, other diamine components generally used in polyimide are contained in a small amount (preferably 30 mol% or less, more preferably 10 mol% or less, more preferably 10 mol) within the range in which the characteristics of the polyimide of the present invention can be expressed. %)) Can also be used together.

  Examples of other diamine components that can be used in the present invention include oxydianiline, p-phenylenediamine, m-phenylenediamine, benzidine, p-methylenebisphenylenediamine, bisaminophenoxybenzene, and bisaminophenoxyphenylhexa. Fluoropropane, bisaminophenylhexafluoropropane, bisaminophenylsulfone, 2,2'-bis (trifluoromethyl) benzidine, cyclohexanediamine, bisaminophenoxyphenylpropane, bisaminohydroxyphenylhexafluoropropane, bisaminophenoxydiphenylsulfone Etc. As other diamine components to be used in combination, p-phenylenediamine, benzidine, 2,2'-bis (trifluoromethyl) benzidine, and cyclohexanediamine are particularly preferable because the coefficient of thermal expansion of polyimide can be lowered.

  The diamine component used in the present invention is not particularly limited, but the purity (in the case of using a plurality of diamine components, the value of the highest purity diamine component or the value of the mixture of all diamine components used) is 90% or more. Preferably, it is 98% or more, more preferably 99% or more. If the purity is less than 90%, the molecular weight of the polyimide precursor is not sufficient, and the resulting polyimide may have poor heat resistance. Purity is a value determined from gas chromatography analysis.

Further, the diamine component used in the present invention is not particularly limited, but the light transmittance (in the case of using a plurality of kinds of diamine components, the value of the diamine component having the best light transmittance or the mixture of all the diamine components used). Value) is 30% or more, preferably 50% or more, more preferably 60% or more. However, the light transmittance here is a transmittance of a wavelength of 400 nm and an optical path length of 1 cm with respect to a solution obtained by dissolving in methanol at a concentration of 8% by mass.
When the light transmittance of the diamine component is 30% or more, coloring of the resulting polyimide is reduced, which is favorable.

In the polyimide precursor of the present invention, X ₁ and X _{2 in} the chemical formula (1) are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, or an alkyl group having 3 to 9 carbon atoms. One of the silyl groups. X ₁ and X ₂ can change the type of functional group and the introduction rate of the functional group by the production method described later.
When X ₁ and X ₂ are hydrogen, the polyimide tends to be easily produced.
Further, when X ₁ and X ₂ are alkyl groups having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, the storage stability of the polyimide precursor tends to be excellent. In this case, X ₁ and X ₂ are more preferably a methyl group or an ethyl group.
Furthermore, when X < ₁ >, X < ₂ > is a C3-C9 alkylsilyl group, there exists a tendency for the thermal linear expansion coefficient of a polyimide to become small. In this case, X ₁ and X ₂ are more preferably a trimethylsilyl group or a t-butyldimethylsilyl group.
The introduction rate of the functional group is not particularly limited, but when an alkyl group or an alkylsilyl group is introduced, each of X ₁ and X ₂ is 25% or more, preferably 50% or more, more preferably 75% or more. Alternatively, it can be an alkylsilyl group.

The polyimide precursor of the present invention has a chemical structure taken by X ₁ and X _2. 1) Polyamic acid (X ₁ and X ₂ are hydrogen), 2) Polyamic acid ester (X ₁ and X ₂ are at least partially alkylated) Group) and 3) polyamic acid silyl ester (at least a part of X ₁ and X ₂ is an alkylsilyl group). And the polyimide precursor of this invention can be easily manufactured with the following manufacturing methods for every classification. However, the manufacturing method of the polyimide precursor of this invention is not limited to the following manufacturing methods.

1) Polyamic acid The polyimide precursor of the present invention comprises a tetracarboxylic dianhydride as a tetracarboxylic acid component and a diamine component in a solvent in an approximately equimolar amount, preferably a molar ratio of the diamine component to the tetracarboxylic acid component [diamine. The number of moles of component / number of moles of tetracarboxylic acid component] is preferably 0.90 to 1.10, more preferably 0.95 to 1.05, for example, imidization at a relatively low temperature of 120 ° C. or less. It can obtain suitably as a polyimide precursor solution composition by reacting, suppressing.
Although it does not limit, more specifically, diamine is melt | dissolved in an organic solvent, Tetracarboxylic dianhydride is added gradually, stirring to this solution, 0-120 degreeC, Preferably it is 5-80. A polyimide precursor is obtained by stirring for 1 to 72 hours in the range of ° C. When the reaction is carried out at 80 ° C. or higher, the molecular weight varies depending on the temperature history at the time of polymerization, and imidization proceeds due to heat, so there is a possibility that the polyimide precursor cannot be produced stably.
Moreover, when the molar ratio of the tetracarboxylic acid component and the diamine component is an excess of the diamine component, if necessary, an amount of a carboxylic acid derivative substantially corresponding to the excess mole number of the diamine component is added, and the tetracarboxylic acid component and the diamine are added. The molar ratio of the components can be approximated to the equivalent. As the carboxylic acid derivative herein, a tetracarboxylic acid that does not substantially increase the viscosity of the polyimide precursor solution, that is, substantially does not participate in molecular chain extension, or a tricarboxylic acid that functions as a terminal terminator and its anhydride, Dicarboxylic acid and its anhydride are preferred.

2) Polyamic acid ester After reacting tetracarboxylic dianhydride with an arbitrary alcohol to obtain a diester dicarboxylic acid, it is reacted with a chlorinating reagent (thionyl chloride, oxalyl chloride, etc.) to obtain a diester dicarboxylic acid chloride. The polyimide precursor is obtained by stirring the diester dicarboxylic acid chloride and the diamine in the range of -20 to 120 ° C, preferably -5 to 80 ° C for 1 to 72 hours. When the reaction is carried out at 80 ° C. or higher, the molecular weight varies depending on the temperature history at the time of polymerization, and imidization proceeds due to heat, so there is a possibility that the polyimide precursor cannot be produced stably. Alternatively, a polyimide precursor can be easily obtained by dehydrating and condensing diester dicarboxylic acid and diamine using a phosphorus condensing agent or a carbodiimide condensing agent.
Since the polyimide precursor obtained by this method is stable, it can be purified by reprecipitation by adding a solvent such as water or alcohol.

3) Polyamic acid silyl ester A diamine and a silylating agent are reacted in advance to obtain a silylated diamine. If necessary, the silylated diamine is purified by distillation or the like. Then, the silylated diamine is dissolved in the dehydrated solvent, and tetracarboxylic dianhydride is gradually added while stirring, and the temperature is 0 to 120 ° C., preferably 5 to 80 ° C. A polyimide precursor is obtained by stirring for 72 hours. When the reaction is carried out at 80 ° C. or higher, the molecular weight varies depending on the temperature history at the time of polymerization, and imidization proceeds due to heat, so there is a possibility that the polyimide precursor cannot be produced stably.
As the silylating agent used here, it is preferable to use a silylating agent not containing chlorine because it is not necessary to purify the silylated diamine. Examples of the silylating agent not containing a chlorine atom include N, O-bis (trimethylsilyl) trifluoroacetamide, N, O-bis (trimethylsilyl) acetamide, and hexamethyldisilazane. N, O-bis (trimethylsilyl) acetamide and hexamethyldisilazane are particularly preferred because they do not contain fluorine atoms and are low in cost.
In addition, amine-based catalysts such as pyridine, piperidine and triethylamine can be used in the silylation reaction of diamine in order to accelerate the reaction. This catalyst can be used as it is as a polymerization catalyst for the polyimide precursor.

  Any of the above production methods can be suitably carried out in an organic solvent, and as a result, the polyimide precursor solution composition of the present invention can be easily obtained.

  The solvent used in preparing the polyimide precursor is preferably an aprotic solvent such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, etc. As long as the monomer component and the polyimide precursor to be produced are dissolved, any type of solvent can be used without any problem, and the structure is not particularly limited. Amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone, α-methyl-γ -Cyclic ester solvents such as butyrolactone, carbonate solvents such as ethylene carbonate and propylene carbonate, glycol solvents such as triethylene glycol, phenol solvents such as m-cresol, p-cresol, 3-chlorophenol, 4-chlorophenol, Acetophenone, 1,3-dimethyl-2-imidazolidinone, sulfolane, dimethyl sulfoxide and the like are preferably employed. In addition, other common organic solvents such as phenol, 0-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, ptyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, Tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, terpene, mineral spirit, Petroleum naphtha solvents can also be used.

  In the present invention, the logarithmic viscosity of the polyimide precursor solution composition is not particularly limited, but the logarithmic viscosity in a 0.5 g / dL N, N-dimethylacetamide solution at 30 ° C. is 0.2 dL / g or more, preferably 0. .3 dL / g or more, more preferably 0.5 dL / g or more, and further preferably 1.0 dL / g or more. When the logarithmic viscosity is less than 0.2 dL / g, the molecular weight of the polyimide precursor is low, and the mechanical strength and heat resistance of the resulting polyimide are lowered.

  In the present invention, the polyimide precursor solution composition comprises at least the polyimide precursor of the present invention and a solvent, and the tetracarboxylic acid component and the diamine component with respect to the total amount of the solvent, the tetracarboxylic acid component and the diamine component. The total amount of is preferably 5% by mass or more, preferably 8% by mass or more, more preferably 9% by mass or more, still more preferably 10% by mass or more, and particularly preferably 15% by mass or more. In general, the content is preferably 60% by mass or less, and preferably 50% by mass or less. This concentration is a concentration approximately approximate to the solid content concentration resulting from the polyimide precursor, but if this concentration is too low, it becomes difficult to control the film thickness of the polyimide film obtained, for example, when producing a polyimide film. Sometimes.

  The solvent used in the polyimide precursor solution composition of the present invention is not a problem as long as the polyimide precursor is dissolved, and is not particularly limited to its structure. Amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone, α-methyl-γ -Cyclic ester solvents such as butyrolactone, carbonate solvents such as ethylene carbonate and propylene carbonate, glycol solvents such as triethylene glycol, phenol solvents such as m-cresol, p-cresol, 3-chlorophenol, 4-chlorophenol, Acetophenone, 1,3-dimethyl-2-imidazolidinone, sulfolane, dimethyl sulfoxide and the like are preferably employed. In addition, other common organic solvents such as phenol, 0-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, ptyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, Tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, terpene, mineral spirit, Petroleum naphtha solvents can also be used. A combination of these can be used.

  The solvent used in preparing the polyimide precursor and the solvent used in the polyimide precursor solution composition described below (hereinafter, these may be collectively referred to as “organic solvent to be used”) are as follows. Properties relating to purity, ie, (a) light transmittance, (b) light transmittance after heat reflux treatment, (c) purity by gas chromatography analysis, (d) percentage of impurity peak by gas chromatography analysis, (e It is preferable that the conditions defined below are satisfied with respect to at least one of the characteristics consisting of the amount of the non-volatile component and (f) the content of the metal component, and it is usually more preferable to satisfy more conditions.

(A) As an organic solvent used, an organic solvent having an optical path length of 1 cm and a light transmittance at a wavelength of 400 nm of 89% or more, more preferably 90% or more, particularly preferably 91% or more. (B) Organic solvent used As an organic solvent having an optical path length of 1 cm after heating and refluxing in nitrogen for 3 hours and a light transmittance at a wavelength of 400 nm of 20% or more, more preferably 40% or more, and particularly preferably 80% or more (c) As an organic solvent, an organic solvent having a purity determined by gas chromatography analysis of 99.8% or more, more preferably 99.9% or more, and further preferably 99.99% or more. (D) As an organic solvent to be used The total amount of impurity peaks that appear on the long-term side with respect to the retention time of the main component peak obtained by gas chromatography analysis is less than 0.2%. The organic solvent is preferably 0.1% or less, particularly preferably 0.05% or less. (E) The amount of the non-volatile component at 250 ° C. of the organic solvent used is 0.1% or less, more preferably 0.8%. (F) Metal component of the organic solvent used (for example, Li, Na, Mg, Ca, Al, K, Ca, Ti, Cr, Mn, Fe) , Co, Ni, Cu, Zn, Mo, Cd) content is 10 ppm or less, more preferably 1 ppm or less, particularly preferably 500 ppb or less, more particularly preferably 300 ppb or less.

  The conditions in these properties are based on the sum of the organic solvents used. That is, the organic solvent used is not limited to one type and may be two or more types. Two or more types of organic solvents are used when a mixed solvent is used in a specific process or when a different solvent is used depending on the process, for example, when a polymerization solvent and a diluent solvent for an additive are different. Also means. When two or more types of organic solvents are used (hereinafter referred to as mixed solvents), the conditions of each characteristic relating to purity are applied to the entire mixed solvent, and when organic solvents are used in multiple steps The condition of each characteristic relating to purity is applied to a mixed solvent in which all organic solvents to be finally contained in the varnish are mixed. Each characteristic may be measured by actually mixing an organic solvent, or the characteristics of each organic solvent may be obtained, and the characteristics of the entire mixture may be obtained by calculation. For example, when 70 parts of solvent A having a purity of 100% and 30 parts of solvent B having a purity of 90% are used, the purity of the organic solvent used is calculated to be 97%.

  The polyimide precursor solution composition of the present invention may contain chemical imidizing agents (acid anhydrides such as acetic anhydride, amine compounds such as pyridine and isoquinoline), antioxidants, fillers, dyes, pigments, silanes as necessary. Coupling agents such as coupling agents, primers, flame retardants, antifoaming agents, leveling agents, rheology control agents (flow aids), release agents and the like can be added.

  The polyimide of the present invention is characterized by comprising the repeating unit represented by the chemical formula (9), and is suitably obtained by subjecting the polyimide precursor of the present invention to a dehydration ring-closing reaction (imidation reaction). Can be manufactured. The imidization method is not particularly limited, and known thermal imidization and chemical imidization methods can be suitably applied. As for the form of the polyimide to be obtained, a film, a laminate of the polyimide film and another substrate, a coating film, powder, beads, a molded body, a foam, a varnish, and the like can be preferably exemplified.

  When the polyimide of the present invention is a film having a thickness of 10 μm, the light transmittance at a wavelength of 400 nm is preferably 55% or more, more preferably 60% or more, and further preferably 70% or more, and has excellent transparency. Have.

  When the polyimide of the present invention is formed into a film having a thickness of 10 μm, the total light transmittance (average transmittance at a wavelength of 380 nm to 780 nm) is preferably 60% or more, more preferably 80% or more, and further preferably 85% or more. And has excellent light transmittance.

  Furthermore, the polyimide of the present invention has an average linear expansion coefficient at 50 ° C. to 200 ° C. of preferably 50 ppm / K, more preferably less than 40 ppm / K, still more preferably less than 30 ppm / K. Has a low coefficient of linear expansion.

  Furthermore, the polyimide of the present invention has an excellent 5% weight loss temperature when formed into a film, preferably 430 ° C. or higher, more preferably 440 ° C. or higher, further preferably 450 ° C. or higher, particularly preferably 490 ° C. or higher. Has heat resistance.

  Furthermore, the polyimide of the present invention has a high elastic modulus, preferably 3.5 GPa or more, more preferably 4 GPa or more, and even more preferably 4.5 GPa or more, when the film is formed into a film. Excellent handling when used.

  In addition, although the film which consists of a polyimide of this invention is based also on a use, Preferably it is about 1 micrometer-250 micrometers as a film thickness, More preferably, it is about 1 micrometer-150 micrometers.

  The polyimide of the present invention has excellent properties such as transparency, bending resistance, and high heat resistance, and also has an extremely low thermal linear expansion coefficient and solvent resistance. Therefore, a transparent substrate for display, a transparent substrate for touch panel, Or it can use suitably in the use of the board | substrate for solar cells.

Below, an example of the manufacturing method of a polyimide film / base material laminated body or a polyimide film using the polyimide precursor of this invention is described. However, it is not limited to the following method.
For example, the polyimide precursor solution composition of the present invention is cast on a base material such as ceramic (glass, silicon, alumina), metal (copper, aluminum, stainless steel), heat-resistant plastic film (polyimide), nitrogen, etc. In an inert gas or in the air, using hot air or infrared rays, and drying in a temperature range of 20 to 180 ° C, preferably 20 to 150 ° C.
Next, the obtained polyimide precursor film is peeled off from the substrate, or the polyimide precursor film is peeled off from the substrate, and the end of the film is fixed, in vacuum, in an inert gas such as nitrogen, or A polyimide film / substrate laminate or a polyimide film can be produced by hot imidization in air using hot air or infrared rays at a temperature of about 200 to 500 ° C., more preferably about 250 to 450 ° C. In order to prevent the resulting polyimide film from being oxidized and deteriorated, it is desirable to carry out the heating imidization in a vacuum or in an inert gas. If the temperature of the heating imidization is not too high, it may be performed in air. The thickness of the polyimide film here (in the case of a polyimide film / substrate laminate) is preferably 1 to 250 μm, more preferably 1 to 150 μm, for transportability in the subsequent steps.

  Further, the imidation reaction of the polyimide precursor contains a dehydration cyclization reagent such as acetic anhydride in the presence of a tertiary amine such as pyridine or triethylamine instead of the heating imidation by the heat treatment as described above. It is also possible to carry out by chemical treatment such as immersion in a solution. Also, a partially imidized polyimide precursor is prepared by previously charging and stirring these dehydrating cyclization reagents in a polyimide precursor solution composition, and casting and drying them on a substrate. In addition, a polyimide film / substrate laminate or a polyimide film can be obtained by further heat-treating this as described above.

  The polyimide film / base laminate or the polyimide film thus obtained can be used to form a flexible conductive substrate by forming a conductive layer on one side or both sides thereof.

A flexible conductive substrate can be obtained, for example, by the following method. That is, as a first method, a conductive material (metal or metal oxide) is formed on the polyimide film surface by sputtering deposition, printing or the like without peeling the polyimide film / substrate laminate from the substrate. , Conductive organic material, conductive carbon, etc.) are formed to produce a conductive layer / polyimide film / substrate laminate. Thereafter, if necessary, a transparent and flexible conductive substrate composed of the conductive layer / polyimide film laminate can be obtained by peeling the electric conductive layer / polyimide film laminate from the base material.
As a second method, the polyimide film is peeled off from the substrate of the polyimide film / substrate laminate to obtain a polyimide film, and a conductive substance (metal or metal oxide, conductive organic substance, A conductive layer of conductive carbon or the like can be formed in the same manner as in the first method, and a transparent and flexible conductive substrate comprising a conductive layer / polyimide film laminate can be obtained.
In the first and second methods, if necessary, before forming a conductive layer on the surface of the polyimide film, a gas barrier layer such as water vapor or oxygen, a light adjusting layer, etc. by sputtering deposition or gel-sol method. An inorganic layer such as may be formed.
The conductive layer is preferably formed with a circuit by a photolithography method, various printing methods, an inkjet method, or the like.

The board | substrate of this invention has a circuit of a conductive layer on the surface of the polyimide film comprised by the polyimide of this invention through a gas barrier layer and an inorganic layer as needed. This substrate is flexible, excellent in transparency, bendability, and heat resistance, and has an extremely low coefficient of thermal expansion and solvent resistance, so that a fine circuit can be easily formed. Therefore, this board | substrate can be used suitably as a board | substrate for displays, a touch panel, or a solar cell.
That is, a transistor (inorganic transistor, organic transistor) is further formed on this substrate by vapor deposition, various printing methods, an ink jet method or the like to manufacture a flexible thin film transistor, and a liquid crystal element, an EL element, a photoelectric transistor for a display device are manufactured. It is suitably used as an element.

  Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples. In addition, this invention is not limited to a following example.

  In each of the following examples, the evaluation was performed by the following method.

<Evaluation of tetracarboxylic acid component and diamine component>
[Light transmittance]
In the tetracarboxylic acid component, a predetermined amount of the tetracarboxylic acid component was dissolved in a solvent (2N aqueous sodium hydroxide solution) to obtain a 10% by mass solution. In the diamine component, a predetermined amount of the diamine component was dissolved in a solvent (methanol) to obtain an 8% by mass solution. Using the prepared solution, using MCPD-300 manufactured by Otsuka Electronics Co., Ltd. and a standard cell with an optical path length of 1 cm, the solvent was used as a blank, and the light transmittance at a wavelength of 400 nm of the tetracarboxylic acid component and the diamine component was measured.

<Evaluation of organic solvent>
[GC analysis: solvent purity]
Using Shimadzu GC-2010, measurement was performed under the following conditions. Purity (GC) was determined from the peak area fraction.
Column: J & W DB-FFAP 0.53mmID × 30m
Column temperature: 40 ° C. (5 min hold) + 40 ° C. to 250 ° C. (10 ° C./min)+250° C. (9 min hold)
Inlet temperature: 240 ° C
Detector temperature: 260 ° C
Carrier gas: Helium 10 ml / min Injection amount: 1 μL

[Non-volatile content]
5 g of solvent was weighed in a glass container and heated in a hot air circulating oven at 250 ° C. for 30 minutes.
It was cooled to room temperature and the residue was weighed. From the mass, the nonvolatile content (% by mass) of the solvent was determined.

[Light transmittance, light transmittance after reflux]
Using a MCPD-300 manufactured by Otsuka Electronics Co., Ltd. and a quartz standard cell having an optical path length of 1 cm, the light transmittance of the solvent at a wavelength of 400 nm was measured using ultrapure water as a blank.

  Further, as the light transmittance after reflux, the light transmittance at a wavelength of 400 nm of a solvent heated under reflux for 3 hours in a nitrogen atmosphere having an oxygen concentration of 200 ppm or less was measured.

[Quantitative determination of metal content]
The metal component contained in the solvent was quantified using ElanDRC II inductively coupled plasma mass spectrometry (ICP-MS) manufactured by Perkin Elmer.

<Evaluation of polyimide precursor solution composition>
[Solid content]
1 g of the polyimide precursor composition was weighed in an aluminum petri dish, heated for 2 hours in a hot air circulating oven at 200 ° C. to remove the solid content, and the solid content concentration (mass%) was determined from the mass of the residue.
[Rotational viscosity]
Using a Toki Sangyo TV-22 E type rotational viscometer, the viscosity of the polyimide precursor solution at a temperature of 25 ° C. and a shear rate of 20 sec ⁻¹ was determined.
[Logarithmic viscosity]
An N, N-dimethylacetamide solution of a polyimide precursor having a concentration of 0.5 g / dL was measured at 30 ° C. using an Ubbelohde viscometer to determine logarithmic viscosity.
[Light transmittance]
The polyimide precursor was diluted with N, N-dimethylacetamide so that a 10% by mass polyimide precursor solution was obtained. Using the prepared solution, MCPD-300 manufactured by Otsuka Electronics Co., Ltd., using a standard cell with an optical path length of 1 cm, N, N-dimethylacetamide was used as a blank, and the light transmittance at a wavelength of 400 nm of a 10% by mass polyimide precursor solution was measured. did.

<Evaluation of polyimide film>
[400 nm light transmittance, total light transmittance]
Using a MCPD-300 manufactured by Otsuka Electronics, the light transmittance at 400 nm and the total light transmittance (average transmittance at 380 nm to 780 nm) of a 10 μm thick polyimide film were measured.
[Elastic modulus, elongation at break]
A polyimide film having a film thickness of 10 μm was punched into a IEC450 standard dumbbell shape as a test piece, and the initial elastic modulus and elongation at break were measured with a length of 30 mm between chucks and a tensile speed of 2 mm / min, using TENSILON manufactured by ORIENTEC. .
[Linear expansion coefficient (CTE)]
A polyimide film having a thickness of 10 μm was cut into a strip having a width of 4 mm to form a test piece, and the temperature was raised to 300 ° C. at a chuck length of 15 mm, a load of 2 g, and a heating rate of 20 ° C./min using TMA-50 manufactured by Shimadzu Corporation. . From the obtained TMA curve, the average coefficient of thermal expansion from 50 ° C. to 200 ° C. was determined.
[Bending resistance]
A polyimide film having a thickness of 10 μm was cut into a strip having a width of 4 mm to form a test piece, which was bent at a radius of curvature of 1 mm under conditions of a temperature of 25 ° C. and a humidity of 50% RH. Subsequent test pieces were visually confirmed, and those having no abnormality were indicated by ◯, and those having cracks were indicated by ×.
[Solvent resistance]
A polyimide film having a thickness of 10 μm was immersed in N, N-dimethylacetamide for 1 hour under the condition of a temperature of 25 ° C., and then the state of the film was visually confirmed. A mark indicating no abnormality was indicated by ◯, a mark indicating a change in wrinkles or a partial shape was indicated by Δ, and a sign indicating dissolution or marked change was indicated by ×.
[5% weight loss temperature]
Using a polyimide film with a film thickness of 10 μm as a test piece and using a differential thermothermal gravimetric simultaneous measurement device (TG / DTA6300) manufactured by SII Nanotechnology, from 25 ° C. to 600 ° C. at a temperature rising rate of 10 ° C./min. The temperature rose. From the obtained weight curve, a 5% weight loss temperature was determined.

Abbreviations, purity, etc. of raw materials used in the following examples are as follows.
[Diamine component]
APBP: bis (4-aminophenyl)-[1,1′-biphenyl] -4,4′-dicarboxylate BABB: 1,4-bis (4-aminobenzoyloxy) benzene ODA: 4,4′-oxy Dianiline [Purity: 99.9% (GC analysis)]
PPD: p-phenylenediamine TFMB: 2,2′-bis (trifluoromethyl) benzidine BAPT: bis (4-aminophenyl) terephthalate [tetracarboxylic acid component]
PMDA-HS: 1R, 2S, 4S, 5R-cyclohexanetetracarboxylic dianhydride [purity: 92.7% (GC analysis), purity as hydrogenated pyromellitic dianhydride (mixture of stereoisomers): 99.9% (GC analysis)]
BPDA-H: 3,3 ′, 4,4′-bicyclohexyltetracarboxylic dianhydride (mixture of stereoisomers) [Purity: 99.9% (GC analysis)]
cis / cis-BTA-H: 1rC7-bicyclo [2.2.2] octane-2c, 3c, 5c, 6c-tetracarboxylic acid-2,3: 5,6-dianhydride [cis / cis-BTA- Purity as H: 99.9% (GC analysis)]
DNDAxx: (4arH, 8acH) -decahydro-1t, 4t: 5c, 8c-dimethanonaphthalene-2t, 3t, 6c, 7c-tetracarboxylic dianhydride [purity: 99.2% (GC analysis)]
[Transmissivity of diamine and acid dianhydride solutions]
BABB: 60%
cis / cis-BTA-H: 100%
DNDAxx: 70%

[Silylating agent]
BSA: N, O-bis (trimethylsilyl) acetamide [solvent]
DMAc: N, N-dimethylacetamide [Solvent purity]
GC analysis:
Main component retention time (min) 14.28
Main component area% 99.99929
Short retention time Impurity peak area% 0.0000
Long retention time Impurity peak area% 0.0071

Nonvolatile content (mass%) <0.001
Light transmittance:
400 nm light transmittance (%) 92
400 nm light transmittance after reflux (%) 92
Metal content:
Na (ppb) 150
Fe (ppb) <2
Cu (ppb) <2
Mo (ppb) <1

  Table 1 shows the structural formulas of the tetracarboxylic acid component and the diamine component used in Examples and Comparative Examples.

[Example 1]
APBP 2.00 g (4.7 mmol) is put in a reaction vessel substituted with nitrogen gas, N, N-dimethylacetamide is charged, and the total amount of monomers (total of diamine component and carboxylic acid component) is 14% by mass. 18.88 g of was added and stirred at 50 ° C. for 2 hours. To this solution, cis / cis-BTA-H 1.18 g (4.7 mmol) was gradually added. The mixture was stirred at 50 ° C. for 6 hours to obtain a uniform and viscous polyimide precursor solution.
The results of measuring the properties of this polyimide precursor solution are shown in Table 2.

A polyimide precursor solution filtered through a PTFE membrane filter is applied to a glass substrate, and then directly on the glass substrate at 120 ° C. for 1 hour, 150 ° C. for 30 minutes, and 200 ° C. for 30 minutes in a nitrogen atmosphere (oxygen concentration of 200 ppm or less). The mixture was heated to 350 ° C. and heated for 5 minutes to thermally imidize to obtain a colorless and transparent polyimide film / glass laminate. Next, the obtained polyimide film / glass laminate was immersed in water and then peeled to obtain a polyimide film having a film thickness of about 10 μm.
The results of measuring the properties of this polyimide film are shown in Table 2.

[Example 2]
A polyimide precursor solution and a polyimide film were obtained in the same manner as in Example 1 except that the diamine component, carboxylic acid component, and solid content concentration were changed as shown in Table 2.
Table 2 shows the results of measuring the properties of the polyimide precursor solution and the polyimide film.

Example 3
Similar to Example 1, except that the diamine component, carboxylic acid component, and solid content concentration were changed as shown in Table 2, and the maximum temperature and time during imidization were changed from 350 ° C. and 5 minutes to 400 ° C. and 1 minute. Thus, a polyimide precursor solution and a polyimide film were obtained.
Table 2 shows the results of measuring the properties of the polyimide precursor solution and the polyimide film.

Example 4
In a reaction vessel substituted with nitrogen gas, 1.06 g (3 mmol) of BABB was placed, N, N-dimethylacetamide was charged, and the total amount of monomers (total of diamine component and carboxylic acid component) was 23% by mass. 0.7 g was added and stirred at room temperature for 1 hour. To this solution, 1.22 g (6 mmol) of BSA was added and stirred at room temperature for 3 hours. Next, 0.68 g (3 mmol) of PMDA-HS was gradually added to this solution. The mixture was stirred at room temperature for 6 hours to obtain a uniform and viscous polyimide precursor solution. And it carried out similarly to Example 1 and formed into a film, and obtained the polyimide film.
Table 2 shows the results of measuring the properties of the polyimide precursor solution and the polyimide film.
Further, the light transmittance at a wavelength of 400 nm and an optical path length of 1 cm of a solution obtained by diluting the obtained polyimide precursor solution to a concentration of 10% by mass was 78%.

Example 5
A polyimide precursor solution and a polyimide film were obtained in the same manner as in Example 4 except that the diamine component, carboxylic acid component, and solid content concentration were changed as shown in Table 2.
Table 2 shows the results of measuring the properties of the polyimide precursor solution and the polyimide film.

Example 6
In a reaction vessel substituted with nitrogen gas, 1.12 g (2.6 mmol) of APBP and 0.032 g (0.3 mmol) of PPD were put, N, N-dimethylacetamide was charged, and the total mass of monomers (diamine component and carboxylic acid component) was added. 15.96 g of an amount so that the total) was 10% by mass was added and stirred at 50 ° C. for 2 hours. To this solution, 0.66 g (2.9 mmol) of PMDA-HS was gradually added. The mixture was stirred at 50 ° C. for 6 hours to obtain a uniform and viscous polyimide precursor solution. And it carried out similarly to Example 1 and formed into a film, and obtained the polyimide film.
Table 2 shows the results of measuring the properties of the polyimide precursor solution and the polyimide film.

Example 7
BAPT 2.00 g (5.7 mmol) is put in a reaction vessel substituted with nitrogen gas, N, N-dimethylacetamide is charged, and the total amount of monomers (total of diamine component and carboxylic acid component) is 19% by mass. Was added and stirred at room temperature for 2 hours. To this solution, 1.74 g (5.7 mmol) of DNDAxx was gradually added. The mixture was stirred at room temperature for 24 hours to obtain a uniform and viscous polyimide precursor solution. And it carried out similarly to Example 1 and formed into a film, and obtained the polyimide film.
Table 2 shows the results of measuring the properties of the polyimide precursor solution and the polyimide film.

[Comparative Examples 1-2]
A polyimide precursor solution and a polyimide film were obtained in the same manner as in Example 1 except that the diamine component, carboxylic acid component, and solid content concentration were changed as shown in Table 2.
Table 2 shows the results of measuring the properties of the polyimide precursor solution and the polyimide film.

[Comparative Example 3]
The same as Example 1 except that the diamine component, carboxylic acid component, and solid content concentration were changed as shown in Table 2, and the maximum temperature and time during imidization were changed from 350 ° C, 5 minutes to 430 ° C, 1 minute. Thus, a polyimide precursor solution and a polyimide film were obtained.
Table 2 shows the results of measuring the properties of the polyimide precursor solution and the polyimide film.

From the results shown in Table 2, it can be seen that, in comparison with Comparative Examples 1 to 3, Examples 1 to 7 using the diamine having an ester bond of the present invention have a smaller linear expansion coefficient and excellent solvent resistance. In addition, the elastic modulus is high, and the handling property is particularly excellent when a thin film is used.
Further, when a bridged ring type tetracarboxylic acid component in which a 6-membered carbon atom further forms a ring by a chemical bond is used (Example 1), a tetracarboxylic acid component having one 6-membered ring structure is used. 5% weight loss temperature is higher than that in the cases (Examples 2 and 4 to 6), and it can be seen that the heat resistance is more excellent.
Further, when a tetracarboxylic acid component having a bridge in the decahydronaphthalene structure is used (Example 3), a bridged ring type tetracarboxylic acid component in which a 6-membered carbon atom further forms a ring by a chemical bond It can be seen that the 5% weight loss temperature is higher than that in the case of using (Example 1), and the heat resistance is more excellent. Further, the elastic modulus is higher, and the handling property is particularly excellent when a thin film is used.
As described above, the polyimide obtained from the polyimide precursor of the present invention has excellent light transmittance and bending resistance, and also has a low linear expansion coefficient, solvent resistance, high heat resistance, and high elastic modulus. The polyimide film of the present invention can be suitably used as a transparent substrate capable of forming a colorless and transparent fine circuit for display applications and the like.

  According to the present invention, a polyimide having excellent characteristics such as transparency, bending resistance, and high heat resistance, and also having a very low linear expansion coefficient, excellent solvent resistance, and high elastic modulus, and a precursor thereof are provided. be able to. The polyimide obtained from this polyimide precursor, and the polyimide are highly transparent, have a low linear expansion coefficient, can easily form a fine circuit, and have a solvent resistance. It can be suitably used to form.

Claims (7)

The polyimide precursor characterized by including the repeating unit represented by following Chemical formula (1).
(In the formula, A is a tetravalent group selected from the group consisting of the following chemical formulas (4) to (5) , and B has 2 at least one ester bond and an aromatic ring in the chemical structure. X ₁ and X ₂ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.)
(In the formula, R 2 represents a CH ₂ group, a C ₂ H ₄ group, an oxygen atom, or a sulfur atom.)
(In the formula, R 3 and R 4 are each independently a CH ₂ group, a CH ₂ CH ₂ group, an oxygen atom, or a sulfur atom.) B is 1 or more types selected from the group which consists of following Chemical formula (6)-(8), The polyimide precursor of Claim 1 characterized by the above-mentioned.
(In the formula, Ar ₁ , Ar ₂ and Ar ₃ are each independently a divalent group having an aromatic ring having 6 to 18 carbon atoms, and n 1 is an integer of 0 to 5).
(In the formula, Ar ₄ , Ar ₅ , Ar ₆ , Ar ₇ and Ar ₈ are each independently a divalent group having an aromatic ring having 6 to 18 carbon atoms, and n2 is 0 to 5) (It is an integer.)
(In the formula, Ar ₉ , Ar ₁₀ , Ar ₁₁ , Ar ₁₂ , Ar ₁₃ are each independently a divalent group having an aromatic ring having 6 to 18 carbon atoms, and n3 is 0 to 5 (It is an integer.) A tetracarboxylic acid component containing 70 mol% or more of a tetracarboxylic acid component giving a repeating unit represented by the chemical formula (1) and 30 mol% or less of the other tetracarboxylic acid component in 100 mol% of all tetracarboxylic acid components And a diamine component containing 70 mol% or more of a diamine component giving a repeating unit represented by the chemical formula (1) and 30 mol% or less of other diamine components in 100 mol% of all diamine components. The polyimide precursor according to any one of claims 1 and 2 . Logarithmic viscosity of the polyimide precursor according to any one of claims 1 to 3 (temperature: 30 ° C., concentration: 0.5 g / dL, solvent: N, N-dimethylacetamide) to be at 0.2 dL / g or more A polyimide precursor solution composition characterized by the above. The polyimide characterized by including the repeating unit represented by following Chemical formula (9).
(In the formula, A is a tetravalent group selected from the group consisting of the following chemical formulas (4) to (5) , and B has 2 at least one ester bond and an aromatic ring in the chemical structure. Valent group.)
(In the formula, R 2 represents a CH ₂ group, a C ₂ H ₄ group, an oxygen atom, or a sulfur atom.)
(In the formula, R 3 and R 4 are each independently a CH ₂ group, a CH ₂ CH ₂ group, an oxygen atom, or a sulfur atom.) The polyimide film formed using the polyimide obtained using the polyimide precursor solution composition of Claim 4 , or the polyimide of Claim 5 . A substrate for a display, a touch panel, or a solar cell, which is formed by using the polyimide obtained by using the polyimide precursor solution composition according to claim 4 or the polyimide according to claim 5 .