WO2020189555A1 - Polyimide - Google Patents

Abstract

A polyimide which comprises a unit derived from a tetracarboxylic dianhydride and a unit derived from a diamine compound and has a structure represented by general formula (1) and in which the chlorine content is 50 μg or less per gram of the polyimide. Thus, provided is a polyimide which has a high light permeability, high modulus of elasticity, high flexibility, high transparency and high solubility in a solvent and is highly applicable to devices. In general formula (1), R represents at least one group selected from the group consisting of a divalent aromatic cyclic group, a divalent heterocyclic group, a divalent alicyclic group and a divalent aliphatic chain group, each optionally having a substituent. * represents a bond.

Description

Polyimide

The present invention relates to a polyimide having high light transmittance, elastic modulus, flexibility, transparency, and solvent solubility, and excellent device applicability.

In recent years, various device applications have been demanding materials having heat resistance, light transmission, high elastic modulus, and flexibility.

For the above applications, for example, aromatic polyimide (for example, "Kapton" manufactured by DuPont) is known to be a light and flexible polyimide having high heat resistance. However, the aromatic polyimide has a brown color and cannot be used in applications that require high light transmission.

Therefore, the development of polyimide showing high light transmission is underway (Patent Document 1). However, in Patent Document 1, although there is a description regarding heat resistance, studies on elastic modulus and flexibility have not been sufficiently conducted.

Polyimide is known as a heat-resistant polymer material. However, many polyimides are insoluble and insoluble, and because of their heat resistance, the molding temperature is high, heating for a long time is required, and the process load is large. That is, if the molding temperature is lowered or the molding time is shortened while maintaining the heat resistance of the resin, the residual solvent increases and the mechanical properties deteriorate.

It is possible to lower the molding temperature by lowering the glass transition temperature (Tg) of polyimide, but the lowering of Tg tends to lower the heat resistance and other physical properties. Therefore, it is generally proposed to lower the Tg at the time of molding and further increase the Tg after molding by cross-linking.

Patent Document 2 proposes a heat-crosslinkable polyimide in which a heat-crosslinkable reactive group is contained at the end of the polyimide as a structure having excellent heat resistance.
Patent Document 3 proposes a terminally modified imide oligomer for lowering the melting temperature.
Patent Document 4 proposes a polyimide for liquid crystal orientation using a photosensitive diamine having an amide group.

International Publication No. 2011/099518 Japanese Unexamined Patent Publication No. 2000-281784 Japanese Unexamined Patent Publication No. 6-32854 JP-A-2019-49700

In the structures presented in Patent Documents 2 and 3, flexibility is impaired by introducing thermal crosslinkability and terminal modification.
In the polyimide shown in Patent Document 4, even if the diamine compound has an amide group, the contribution to the improvement of the elastic modulus is small.

An object of the present invention is to provide a polyimide having high light transmittance, elastic modulus, flexibility, transparency, and solvent solubility, and excellent device applicability.

The present inventor has found that a polyimide containing a specific structure can solve the above-mentioned problems, and has completed the present invention.

That is, the present invention has the following gist.

[1] A polyimide having a unit derived from a tetracarboxylic dianhydride and a unit derived from a diamine compound, having a structure represented by the following general formula (1), and having a chlorine content of 50 μg or less in 1 g of the polyimide. There is polyimide.

In the general formula (1), R represents at least one selected from the group consisting of a divalent aromatic ring group, a heterocyclic group, an alicyclic group and a chain aliphatic group which may have a substituent. .. * Indicates a bond.
[2] The polyimide according to [1], which has an aliphatic skeleton as a unit derived from the tetracarboxylic dianhydride.
[3] The polyimide according to [1] or [2], wherein R of the general formula (1) is at least one selected from the group consisting of a divalent aromatic ring group and a chain aliphatic group. ..
[4] The polyimide according to any one of [1] to [3], wherein the structure represented by the general formula (1) includes at least a structure obtained by a reaction of a tetracarboxylic dianhydride and a dihydrazide compound.
[5] The polyimide according to any one of [1] to [4], which has an elastic modulus at 25 ° C. of 4 GPa or more.
[6] The polyimide according to any one of [1] to [5], which is dissolved in an aprotic polar solvent at 25 ° C. in an amount of 5% by mass or more and 80% by mass or less.
[7] The polyimide according to any one of [1] to [6], wherein the glass transition temperature is 150 ° C. or higher.
[8] A composition containing the polyimide and the solvent according to any one of [1] to [7], wherein the absolute value of the difference between the solubility parameter of the solvent and the solubility parameter based on the repeating unit of the polyimide is 2 or more. The composition.
[9] A film obtained from the composition according to [8].
[10] The film according to [9], wherein the film thickness is 1 μm or more and 300 μm or less.
[11] The film according to [9] or [10], wherein the film is obtained by a casting method.
[12] A laminate having a hard coat layer on the film according to any one of [9] to [11].
[13] The laminate according to [12], wherein the hard coat layer has a film thickness of 50 μm or more and 200 μm or less.

According to the present invention, it is possible to provide a polyimide having high light transmittance, elastic modulus, flexibility, transparency, and solvent solubility, and excellent device applicability.

Hereinafter, embodiments of the present invention will be described in detail. The following examples and methods are examples (representative examples) of the embodiments of the present invention, and the present invention is not limited to these contents as long as the gist of the present invention is not deviated.

The polyimide of the present invention contains an imide ring in the main chain, and is composed of at least one selected from polyamic acid, polyamic acid ester, and polyimide.

In the present invention, room temperature means 25 ° C. unless otherwise specified. Further, in the present invention, the "elastic modulus" refers to the "storage elastic modulus".

The polyimide of the present invention is a polyimide having a unit derived from a tetracarboxylic dianhydride and a unit derived from a diamine compound, has a structure represented by the following general formula (1), and has a chlorine content in 1 g of the polyimide. It is characterized in that it is 50 μg or less.

In the general formula (1), R represents at least one selected from the group consisting of a divalent aromatic ring group, a heterocyclic group, an alicyclic group and a chain aliphatic group which may have a substituent. .. * Indicates a bond.

[mechanism]
The reasons why the polyimide of the present invention has high light transmittance, elastic modulus, flexibility, transparency, solvent solubility, and excellent device applicability can be mentioned as follows.

By introducing the structure represented by the general formula (1) into polyimide, hydrogen-bonding crosslinked structures that are not charge transfer complexes are formed on both sides of the organic group R, thereby reducing the molecular chain orientation and improving transparency. The elastic modulus can be increased without impairing the flexibility. Further, by forming the hydrogen-bonding crosslinked structure on both sides of the organic group R, the flatness of the polyimide molecule can be lowered and the solvent solubility can be improved.

Further, when the amount of chlorine in 1 g of polyimide is 50 μg or less, the device applicability can be made excellent.
Specifically, in the manufacturing process of a device or the like to which this polyimide is applied, contamination of the manufacturing line due to elution and volatilization of chlorine can be suppressed. Further, when chlorine is eluted and volatilized from the polyimide, it is possible to suppress corrosion of other members and layers constituting the device and adverse effects on electrical characteristics such as insulation. Further, when the amount of chlorine in 1 g of polyimide is 50 μg or less, it is possible to suppress a decrease in transparency (YI value) of polyimide.

The structure represented by the general formula (1) is derived from the reaction between the dicarboxylic acid compound and the diamine compound and / or the reaction between the tetracarboxylic dianhydride and the dihydrazide compound. Examples of the dicarboxylic acid compound include compounds such as aromatic dicarboxylic acid, heterocyclic dicarboxylic acid, alicyclic dicarboxylic acid, and chain aliphatic dicarboxylic acid. The dicarboxylic acid compound can also be used as an acid halide in which a carboxyl group is halogenated in order to improve reactivity, for example, an acid chloride in which a carboxyl group is chlorinated. In the present invention, the dicarboxylic acid chloride is used as the dicarboxylic acid compound. Even when a halide such as the above is used, it is said to be a structure derived from the reaction between the dicarboxylic acid compound and the diamine compound.

[Amount of chlorine in 1 g of polyimide]
The amount of chlorine in 1 g of the polyimide of the present invention is 50 μg or less, preferably 40 μg or less, more preferably 30 μg or less, still more preferably 20 μg or less. The lower limit of the amount of chlorine is not particularly limited and may be 0 μg. When the amount of chlorine is not more than the above upper limit, it is possible to suppress an adverse effect at the time of manufacturing a device to which this polyimide is applied and a device. Further, when the amount of chlorine is not more than the above upper limit, it is possible to suppress a decrease in the transparency (YI value) of the polyimide.

The method for reducing the amount of chlorine in 1 g of the polyimide of the present invention to 50 μg or less is not particularly limited, but a method for obtaining a polyimide by reacting a tetracarboxylic dianhydride with a dihydrazide compound; a chlorine-based solvent or the like used in the production of the polyimide is used. Methods of avoiding the use of solvents; methods of avoiding the use of glassware during polyimide production; methods of performing pure water cleaning; and combinations of these methods can be mentioned.

In particular, as a method for obtaining the polyimide of the present invention, it is preferable to use a method for obtaining a polyimide by reacting a tetracarboxylic dianhydride with a dihydrazide compound.

As a method for obtaining a polyimide having a structure represented by the general formula (1), there is also a method using an acid chloride in which a carboxyl group is chlorinated, but this method tends to increase the amount of chlorine in 1 g of polyimide.

[Polyimide structure]
The structure of the polyimide of the present invention is not particularly limited as long as it has the structure represented by the general formula (1), but may be expressed as a unit derived from tetracarboxylic dianhydride (hereinafter, referred to as a tetracarboxylic acid residue). ) And a unit derived from a diamine compound (hereinafter, may be referred to as a diamine residue).

<Unit derived from tetracarboxylic dianhydride (tetracarboxylic acid residue)>
The tetracarboxylic dianhydride that induces the tetracarboxylic acid residue contained in the polyimide of the present invention is an aliphatic tetracarboxylic dianhydride (the aliphatic tetracarboxylic dianhydride is an alicyclic tetracarboxylic dianhydride). Includes anhydrides and chain aliphatic tetracarboxylic dianhydrides), aromatic tetracarboxylic dianhydrides and the like. One of these tetracarboxylic dianhydrides may be used alone, or two or more thereof may be used in any ratio and combination.
The tetracarboxylic acid residue contained in the polyimide of the present invention preferably has an aliphatic skeleton because it can further suppress the formation of a charge transfer complex and enhance light transmission and solvent solubility.

<< Aliphatic tetracarboxylic dianhydride >>
Examples of the aliphatic tetracarboxylic dianhydride include an alicyclic tetracarboxylic dianhydride and a chain aliphatic tetracarboxylic dianhydride.

(Alicyclic tetracarboxylic dianhydride)
Examples of the alicyclic tetracarboxylic dianhydride include 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1 , 2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4 -Cyclobutanetetracarboxylic dianhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, tricyclo [6.4.0.0 ^{2, 7} ] Dodecane-1,8: 2,7-tetracarboxylic dianhydride, Bicyclo [2.2.2] Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 4- Examples thereof include (2,5-dioxo tetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride.

(Chain aliphatic tetracarboxylic dianhydride)
Examples of the chain aliphatic tetracarboxylic dianhydride include ethylenetetracarboxylic dianhydride, butanetetracarboxylic dianhydride, meso-butane-1,2,3,4-tetracarboxylic dianhydride and the like. Can be mentioned.

Among the aliphatic tetracarboxylic dianhydrides, the polyimide of the present invention preferably has a tetracarboxylic acid residue derived from the alicyclic tetracarboxylic dianhydride, and among them, 3,3', 4, Tetracarboxylic acid residue derived from 4'-biscyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride It is more preferable to have a group, and it is further preferable to have a tetracarboxylic acid residue derived from 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride.

<< Aromatic Tetracarboxylic Acid Dianhydride >>
Examples of the aromatic tetracarboxylic acid dianhydride include tetracarboxylic acid dianhydride having one aromatic ring in one molecule, tetracarboxylic acid dianhydride having two or more independent aromatic rings in one molecule, and 1 Examples thereof include tetracarboxylic acid dianhydride having a condensed aromatic ring in the molecule.

Among these, tetracarboxylic dianhydride having one aromatic ring in one molecule or tetracarboxylic dianhydride having one aromatic ring in one molecule tends to be easy to control the viscosity at the time of production, improve solvent solubility, and improve coating flexibility. A tetracarboxylic dianhydride having two or more independent aromatic rings in one molecule is preferable, and a tetracarboxylic dianhydride having two or more independent aromatic rings in one molecule is particularly preferable.

(Tetracarboxylic dianhydride having one aromatic ring in one molecule)
Examples of the tetracarboxylic dianhydride having one aromatic ring in one molecule include pyromellitic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride and the like.

(Tetracarboxylic dianhydride having two or more independent aromatic rings in one molecule)
Examples of the tetracarboxylic dianhydride having two or more independent aromatic rings in one molecule include 1,1-bis (2,3-dicarboxyphenyl) ethanedianhydride and bis (2,3-di). Carboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4) -Dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (2,3- Dicarboxyphenyl) ether dianhydride, 3,3', 4,4'-benzophenonetetracarboxylic dianhydride, 2,2', 3,3'-benzophenonetetracarboxylic dianhydride, 4,4'- Oxydiphthalic dianhydride, 4,4- (p-phenylenedioxy) diphthalic dianhydride, 4,4- (m-phenylenedioxy) diphthalic dianhydride, 2,2', 6,6'- Examples thereof include biphenyltetracarboxylic dianhydride.

(Tetracarboxylic dianhydride having a condensed aromatic ring in one molecule)
Examples of the tetracarboxylic dianhydride having a condensed aromatic ring in one molecule include 1,2,5,6-naphthalenedicarboxylic dianhydride, 1,4,5,8-naphthalenedicarboxylic dianhydride, 2, 3,6,7-naphthalenedicarboxylic acid dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7 , 8-Phenyltetracarboxylic dianhydride and the like.

<< Other tetracarboxylic dianhydrides >>
As the tetracarboxylic dianhydride, in addition to the above, a silicone-based tetracarboxylic dianhydride or a tetracarboxylic dianhydride containing a fluorine atom can also be used. Examples of the tetracarboxylic dianhydride containing a fluorine atom include 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropanedianhydride (also known as). : 4,4'-(hexafluoroisopropyridene) -diphthalic dianhydride), 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane Dichloride, 2,2'-bis (trifluoromethyl) -4,4', 5,5'-biphenyltetracarboxylic dianhydride, 4,4'-(hexafluorotrimethylethylene) diphthalic acid dianhydride , 4,4'-(octafluorotetramethylene) diphthalic acid dianhydride, 2,2'-bis (trifluoromethyl) -4,4', 5,5'-biphenyltetracarboxylic dianhydride, 4, 4'-(hexafluorotrimethylethylene) diphthalic acid dianhydride, 4,4'-(octafluorotetramethylene) diphthalic acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1 , 1,3,3,3-hexafluoropropanedianhydride, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropanedianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,1,3,3,3-hexafluoropropanedianhydride, 2,2-bis (2,3-dicarboxyphenyl) -1 , 1,1,3,3,3-hexafluoropropanedianhydride and the like.

The ratio of the tetracarboxylic acid residue derived from the aliphatic tetracarboxylic acid dianhydride to the total tetracarboxylic acid residue contained in the polyimide of the present invention is not particularly limited, but is preferably 10 mol% or more, more preferably 25 mol% or more. Preferably, 40 mol% or more is further preferable, 50 mol% or more is further preferable, 60 mol% or more is particularly preferable, and 65 mol% or more is most preferable. The upper limit of the ratio of the tetracarboxylic acid residue derived from the aliphatic tetracarboxylic acid dianhydride to the total tetracarboxylic acid residue contained in the polyimide of the present invention is not particularly limited and may be 100 mol%. When the ratio of the tetracarboxylic acid residue derived from the aliphatic tetracarboxylic dianhydride is at least the above lower limit value, the solubility in a solvent tends to be high.

<Unit derived from diamine compound (diamine residue)>
The diamine residue contained in the polyimide of the present invention is not particularly limited. Examples of the compound for inducing the diamine residue contained in the polyimide of the present invention include aromatic diamine compounds and aliphatic diamine compounds (aliphatic diamine compounds include alicyclic diamine compounds and chain aliphatic diamine compounds). Diamine compounds can be mentioned. The diamine residue can also be derived from a diisocyanate compound, a dihydrazide compound, or the like. As the compound for inducing these diamine residues, one kind may be used alone, or two or more kinds may be used in any ratio and combination.

<< Aromatic diamine compound >>
Examples of the aromatic diamine compound include a diamine compound having one aromatic ring in one molecule, a diamine compound having a condensed aromatic ring in one molecule, and a diamine compound having two or more independent aromatic rings in one molecule. Can be mentioned.

(Diamine compound having one aromatic ring in one molecule)
Examples of the diamine compound having one aromatic ring in one molecule include 1,4-phenylenediamine, 1,2-phenylenediamine, 1,3-phenylenediamine, 4-fluoro-1,2-phenylenediamine, and the like. 4-Fluoro-1,3-phenylenediamine, 3-trifluoromethyl-1,5-phenylenediamine, 4-trifluoromethyl-1,5-phenylenediamine, 4-trifluoromethyl-1,2-phenylenediamine, Examples thereof include 2-trifluoromethyl-1,4-phenylenediamine and 2,5-dimethyl-1,4-phenylenediamine.

(Diamine compound having a condensed aromatic ring in one molecule)
Examples of the diamine compound having a condensed aromatic ring in one molecule include 4,4'-(9-fluorenylidene) dianiline, 2,7-diaminofluorene, 1,5-diaminonaphthalene, and 3,7-diamino-2,8-. Examples thereof include dimethyldibenzothiophene 5,5-dioxide.

(Diamine compound having two or more independent aromatic rings in one molecule)
Diamine compounds having two or more independent aromatic rings in one molecule include 4,4'-(biphenyl-2,5-diylbisoxy) bisaniline and 4,4'-diamino as having a biphenyl structure. -3,3'-dimethylbiphenyl, 4,4'-diamino-2,2'-dimethylbiphenyl (also known as 3,3'-dimethylbenzidine or m-trizine), 4,4'-bis (4-aminophenoxy) ) Biphenyl, 4,4'-diamino-2,2'-dimethoxybiphenyl, 4,4'-diamino-3,3'-dimethoxybiphenyl, 4,4'-diamino-2,2'-dichlorobiphenyl, 4, 4'-diamino-3,3'-dichlorobiphenyl, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 4,4'-diamino-2-methyl-2'-trifluoromethyl Examples include biphenyl. Assuming that the aromatic rings are linked by a linker, 4,4-diaminozensanilide, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1,4-bis (4-aminophenoxy) benzene, 1 , 3-bis (4-aminophenoxy) benzene, bis (4- (4-aminophenoxy) phenyl) sulfone, 2,2-bis (4- (4-aminophenoxy) phenyl) propane, bis (4- (3) -Aminophenoxy) phenyl) sulfone, 1,3-bis (4-aminophenoxy) neopentane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, N- (4-Aminophenoxy) -4-aminobenzamine, bis (3-aminophenyl) sulfone, norbornandiamine, bis (4- (4-aminophenoxy) phenyl) sulfone, bis (4- (3-aminophenoxy) phenyl ) Sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, N- [4- (4-aminophenoxy) phenyl] -4-aminobenzamide, 4,4-diaminobenzanilide, bis ( 3-Aminophenyl) sulfone and the like. Those having a fluorine atom include 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane and 2,2-bis [4- {4-amino-2- (trifluoromethyl) phenoxy} phenyl. ] Hexafluoropropane, 2,2-bis (3-amino-4-methylphenyl) hexafluoropropane, 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, 2,2-bis (4) -Aminophenyl) hexafluoropropane, 2,2-bis (3-aminophenyl) hexafluoropropane, 2,2-bis {4- (4-aminophenoxy) -3,5-dibromophenyl} hexafluoropropane, etc. Can be mentioned.

Among them, since the elastic modulus tends to be high, a diamine compound having a biphenyl structure or a diamine compound in which aromatic rings are linked to each other by a linker is preferable, and a diamine compound having a biphenyl structure is more preferable.

<< Aliphatic diamine compound >>
Examples of the aliphatic diamine compound include an alicyclic diamine compound and a chain aliphatic diamine compound.

(Alicyclic diamine compound)
Examples of the alicyclic diamine compound include 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1,4-diaminocyclohexane, and 4,4'-methylenebis (cyclohexylamine). Examples thereof include 4,4'-methylenebis (2-methylcyclohexylamine).

(Chain aliphatic diamine compound)
Examples of the chain aliphatic diamine compound include 1,2-ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,6-hexamethylenediamine, and 1,5-. Examples thereof include diaminopentane, 1,10-diaminodecane, 1,2-diamino-2-methylpropane, 2,3-dimethyl-2,3-butanediamine, 2-methyl-1,5-diaminopentane and the like.

<< Diisocyanate compound >>
A structure derived from a diisocyanate compound can also be used as the diamine residue. Examples of the diisocyanate compound include aromatic diisocyanate compounds and aliphatic diisocyanate compounds. One of these diisocyanate compounds may be used alone, or two or more of these diisocyanate compounds may be used in any ratio and combination.

(Aromatic diisocyanate compound)
Examples of the aromatic diisocyanate compound include 4,4'-diisocyanato-3,3'-dimethylbiphenyl, 2,2-bis (4-isocyanatophenyl) hexafluoropropane, and 4,4'-diisocyanato-3,3. '-Dimethyldiphenylmethane, 1,5-diisocyanatonaphthalene, 4,4'-methylenediphenyl diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylenediisocyanate, 1,3-bis (isocyanatomethyl) ) Benzene, toluene diisocyanate and the like.

(Aliphatic diisocyanate compound)
Examples of the aliphatic diisocyanate compound include 1,3-bis (isocyanatomethyl) cyclohexane, hexamethylene diisocyanate, and isophorone diisocyanate.

<< Dihydrazide compound >>
Examples of the dihydrazide compound include dihydrazide compounds exemplified in the structure represented by the general formula (1) described later.

The diamine compound, diisocyanate compound, etc. that induce the diamine residue contained in the polyimide of the present invention may be only one type or may contain two or more types, but the heat resistance of the obtained polyimide is increased. Because of the tendency, aromatic diamine compounds are preferable, and diamine compounds having a fused aromatic ring in one molecule and diamine compounds having two or more independent aromatic rings in one molecule are more preferable.

The ratio of the diamine residue derived from the aromatic diamine compound to the total diamine residue contained in the polyimide of the present invention is not particularly limited, but is usually preferably 10 mol% or more, more preferably 20 mol% or more, and 40 mol% or more. More preferred. There is no upper limit to the ratio of the diamine residue derived from the aromatic diamine compound to the total diamine residue contained in the polyimide of the present invention, and it may be 100 mol%. When the ratio of the diamine residue derived from the aromatic diamine compound is at least the above lower limit value, the heat resistance is increased and the production is facilitated, which is preferable.

[Structure represented by general formula (1)]
In the general formula (1), R represents at least one selected from the group consisting of a divalent aromatic ring group, a heterocyclic group, an alicyclic group and a chain aliphatic group which may have a substituent. ..

The aromatic ring and the heterocycle are not particularly limited, and may be a fused ring. The alicyclic is not particularly limited, but is preferably a 3- to 10-membered ring. The chain aliphatic group is also not particularly limited, but is preferably a linear group having 1 to 20 carbon atoms.
These aromatic ring groups, heterocyclic groups, alicyclic groups and chain aliphatic groups may have substituents. Examples of the substituent which may be possessed include an alkyl group, an alkoxy group, an alkyl halide group, a hydroxyl group, a carboxy group and the like.

These aromatic ring groups, heterocyclic groups, alicyclic groups and chain aliphatic groups may be used alone or in combination.

It is preferable that R is at least one selected from the group consisting of an aromatic ring group and a chain aliphatic group because the molecular weight can be easily controlled and the production stability is good. Among these, as the aromatic ring group, a group composed of a benzene ring, a naphthalene ring, a biphenyl ring, a biphenyl ether, a benzophenone, a phenyl sulfide, a biphenyl sulfoxide, and a biphenyl sulfone is preferable, and a group having a monocyclic ring or two aromatic rings is preferable. Is preferable. On the other hand, the chain aliphatic group preferably has 1 or more and 10 or less carbon atoms. When R is these groups, the effect of the present invention tends to be particularly easily obtained.

Specific examples of the structure represented by the general formula (1) include structures derived from each of the compounds listed in the reaction of tetracarboxylic dianhydride and dihydrazide compound, which will be described later.

The polyimide of the present invention may have only one type of the structure represented by the general formula (1) or may have a plurality of types, but at least for the reaction between the tetracarboxylic dianhydride and the dihydrazide compound. It preferably has a derived structure.

The amount introduced into the polyimide having the structure represented by the general formula (1) is not particularly limited, but the concentration of the amide bond with respect to the imide ring of the main chain is preferably 1 mol% or more, more preferably 5 mol% or more. 8 mol% or more is more preferable. The amount introduced into the polyimide having the structure represented by the general formula (1) is preferably 900 mol% or less, more preferably 700 mol% or less, further preferably 500 mol% or less, and particularly preferably 400 mol% or less. It is preferable that the amount of the structure represented by the general formula (1) introduced in the polyimide is within this range because the solvent solubility and the elastic modulus tend to be compatible with each other.

The ratio of tetracarboxylic acid residue, diamine residue, dicarboxylic acid residue, and dihydrazide residue contained in the polyimide of the present invention can be determined by analyzing the composition of the raw material monomer by NMR, solid NMR, IR, or the like. Can be done. The proportion of these residues can be determined by gas chromatography (GC), ¹ H-NMR, ¹³ C-NMR, two-dimensional NMR, mass spectrometry, etc. after dissolution in alkali.

The method for obtaining the structure represented by the general formula (1) in the polyimide of the present invention is not particularly limited, and examples thereof include a method obtained by reacting a tetracarboxylic dianhydride with a dihydrazide compound.

<< Structure derived from the reaction of tetracarboxylic dianhydride and dihydrazide compound >>
(Tetracarboxylic dianhydride)
Examples of tetracarboxylic dianhydrides include aromatic tetracarboxylic dianhydrides and aliphatic tetracarboxylic dianhydrides (aliphatic tetracarboxylic dianhydrides are alicyclic tetracarboxylic dianhydrides and chain aliphatics. Includes tetracarboxylic dianhydride). One of these tetracarboxylic dianhydrides may be used alone, or two or more thereof may be used in any ratio and combination.

Examples of the tetracarboxylic dianhydride compound to be reacted with the dihydrazide compound include the compounds described above in the description of the tetracarboxylic acid residue, and the preferable range is also the same.

(Dihydrazide compound)
The dihydrazide compound is not particularly limited, and examples thereof include aromatic dihydrazide compounds and aliphatic dihydrazide compounds (including alicyclic dihydrazide compounds and chain aliphatic dihydrazide compounds). One of these dihydrazide compounds may be used alone, or two or more thereof may be used in any ratio and combination.

Examples of the aromatic dihydrazide compound include monocyclic isophthalic acid dihydrazide, terephthalic acid dihydrazide, phthalic acid dihydrazide, 2,5-dimethylterephthalic acid dihydrazide, and the like; 4,4'-carbonyl having two or more independent aromatic rings. Dihydrazide benzoate, 2,2'-biphenyldicarboxylic acid dihydrazide, 4,4'-biphenyldicarboxylic acid dihydrazide, 2,2-bis (4-carboxyphenyl) hexafluoropropanedihydrazide, 4- (carboxymethyl) dihydrazide benzoate , 4,4'-oxybis benzoic acid dihydrazide, 4,4'-sulfonyl dibenzoic acid dihydrazide, 1,2-bis (4-carboxyphenyl) ethanedihydrazide, 4,4'-stylbenzicarboxylic acid dihydrazide, etc .; 1,4-Naphthalenedicarboxylic acid dihydrazide, 2,3-naphthalenedicarboxylic acid dihydrazide, etc .; 2,2'-bisinconic acid dihydrazide, 2,2'-binicotinic acid dihydrazide, 2,2'-biisonicotinic acid dihydrazide having a heterocycle , 2,2'-bipyridine-5,5'-dicarboxylic acid dihydrazide, 2,2'-bipyridine-6,6'-dicarboxylic acid dihydrazide, 2,5-furandicarboxylic acid dihydrazide and the like.

Examples of the alicyclic dihydrazide compound include bicyclo [2.2.2] octane-1,4-dicarboxylic acid dihydrazide, 1,3-adamantandicarboxylic acid dihydrazide, cis-4-cyclohexene-1,2-dicarboxylic acid dihydrazide, and 1, , 4-Cyclohexanedicarboxylic acid dihydrazide, 1,3-cyclohexanedicarboxylic acid dihydrazide, decahydro-1,4-naphthalenedicarboxylic acid dihydrazide and the like.

Examples of the chain aliphatic dihydrazide compound include adipic acid dihydrazide, azelaic acid dihydrazide, dodecanoic acid dihydrazide, malonic acid dihydrazide, sebacic acid dihydrazide, succinate dihydrazide, and oxalyl dihydrazide.

As the dihydrazide compound, a monocyclic aromatic dihydrazide compound and a dihydrazide compound having two or more independent aromatic rings tend to improve the elastic modulus, and are preferable.

[Elastic modulus of polyimide]
The elastic modulus of the polyimide of the present invention can be measured by viscoelasticity measurement. The elastic modulus of the polyimide of the present invention is not particularly limited, but the elastic modulus at 25 ° C. is preferably 4 GPa or more, more preferably 4.5 GPa or more, still more preferably 4.8 GPa or more, and particularly preferably. It is 5 GPa or more. On the other hand, the elastic modulus of the polyimide of the present invention at 25 ° C. is preferably 10 GPa or less, more preferably 9 GPa or less, and further preferably 8 GPa or less. When the elastic modulus at 25 ° C. is in this range, the abrasion resistance of the polyimide is maintained, which is preferable.

A polyimide having an elastic modulus in the above range can be realized, for example, by introducing the structure represented by the general formula (1) into the polyimide at a predetermined ratio, introducing a crosslinked structure into the polyimide, or the like.

[Molecular weight of polyimide]
The molecular weight of the polyimide of the present invention is not particularly limited, but is preferably a polystyrene-equivalent number average molecular weight (Mn) of 500 or more, more preferably 1000 or more, and further preferably 1500 or more. On the other hand, this molecular weight is preferably 80,000 or less, more preferably 60,000 or less, still more preferably 40,000 or less. When the number average molecular weight (Mn) of the polyimide is in this range, solvent solubility, solution viscosity, and the like are in a range that can be easily handled by ordinary equipment, which is preferable.
The polystyrene-equivalent number average molecular weight (Mn) of the polyimide of the present invention can be determined by gel permeation chromatography (GPC).

The mass average molecular weight (Mw) of the polyimide of the present invention is preferably 1000 or more, more preferably 2000 or more, still more preferably 5000 or more. On the other hand, this molecular weight is preferably 300,000 or less, more preferably 200,000 or less, still more preferably 100,000 or less. When the mass average molecular weight (Mw) of the polyimide is in this range, the solvent solubility, solution viscosity, and the like are in a range that can be easily handled by ordinary equipment, which is preferable.
The mass average molecular weight (Mw) of the polyimide of the present invention can be measured by the same method as the number average molecular weight (Mn).

The molecular weight distribution (PDI: Mw / Mn) of the polyimide of the present invention is usually 1 or more, preferably 1,1 or more, and more preferably 1.2 or more. On the other hand, Mw / Mn is usually 20 or less, preferably 15 or less, and more preferably 10 or less. When Mw / Mn is in this range, the uniformity and smoothness of the obtained molded product tend to be excellent.

[Glass transition temperature of polyimide]
The glass transition temperature (Tg) of the polyimide of the present invention is not particularly limited, but is preferably 150 ° C. or higher, more preferably 180 ° C. or higher, still more preferably 200 ° C. or higher, still more preferably 260 ° C. or higher, particularly preferably. It is 270 ° C. or higher, most preferably 280 ° C. or higher. On the other hand, the glass transition temperature (Tg) of polyimide is preferably 400 ° C. or lower, more preferably 380 ° C. or lower. When the glass transition temperature (Tg) of polyimide is in this range, the heat resistance of the obtained molded product is improved, and the residual solvent in low-load process molding such as suppression of molding temperature and molding under air is reduced. Tend to do.
The glass transition temperature (Tg) of polyimide corresponds to the peak temperature (Ttanδ) of α relaxation of tanδ.

[Polyimide manufacturing method]
The method for producing the polyimide of the present invention is not particularly limited, and the polyimide can be produced by a conventionally known method. For example, a method of producing a polyimide precursor from a tetracarboxylic acid dianhydride and / or a dicarboxylic acid compound and a diamine compound, a diisocyanate compound and / or a dihydrazide compound, and imidizing the polyimide precursor to obtain a polyimide; tetracarboxylic acid dianhydride. And / or a method of directly producing a polyimide from a dicarboxylic acid compound and a diamine compound, a diisocyanate compound, and / or a dihydrazide compound;

In a usual method for producing a polyimide using a tetracarboxylic dianhydride and a diamine compound, a diisocyanate compound may be used instead of the diamine compound, or the diamine compound and the diamine compound may be used in combination.
The dihydrazide compound can be reacted in the same manner as the diamine compound, and the dicarboxylic acid compound can be reacted in the same manner as the tetracarboxylic dianhydride. The dicarboxylic acid compound can also be used as a chain extender after producing polyimide from a tetracarboxylic dianhydride and a diamine compound, a diisocyanate compound and / or a dihydrazide compound.

Hereinafter, "tetracarboxylic acid dianhydride and / or dicarboxylic acid compound" is referred to as "tetracarboxylic acid dianhydride, etc.", and "one or more of diamine compounds, diisocyanate compounds and dihydrazide compounds" is referred to as "diamine compound, diisocyanate compound and dihydrazide compound". A method for producing the polyimide of the present invention by reacting a tetracarboxylic acid dianhydride or the like with a diamine compound or the like will be described with reference to "diamine compound or the like".

<< Method of producing polyimide via polyimide precursor >>
(Structure of polyimide precursor)
When the polyimide is produced via the polyimide precursor, the polyimide precursor can be obtained, for example, by reacting a tetracarboxylic dianhydride or the like with a diamine compound or the like in a solvent.
In this case, the order of addition and the method of addition of the tetracarboxylic dianhydride and the like and the diamine compound and the like are not particularly limited. For example, a polyimide precursor can be obtained by sequentially adding a diamine compound or the like and a tetracarboxylic dianhydride or the like to a solvent and stirring the mixture at an appropriate temperature.

The amount of the tetracarboxylic dianhydride or the like is usually 0.7 mol or more, preferably 0.8 mol or more, and usually 1.3 mol or less, preferably 1.2 mol, based on 1 mol of the diamine compound or the like. It is as follows. By setting the amount of tetracarboxylic dianhydride or the like in such a range, the yield of the obtained polyimide precursor tends to be improved.

The concentration of tetracarboxylic dianhydride, etc., diamine compound, etc. in the reaction solution can be appropriately set according to the reaction conditions and the viscosity of the obtained polyimide precursor.

The total concentration of the tetracarboxylic dianhydride and the like and the diamine compound and the like is not particularly limited, but is usually 1% by mass or more, preferably 5% by mass or more, and usually 70% by mass or less, based on the total amount of the reaction solution. It is preferably 50% by mass or less. If the concentrations of the tetracarboxylic dianhydride and the like and the diamine compound in the reaction solution are not too low, the molecular weight tends to be extended. When the concentrations of the tetracarboxylic dianhydride and the like and the diamine compound in the reaction solution are not too high, the viscosity of the reaction solution does not become too high and stirring tends to be easy.

The temperature at which the tetracarboxylic dianhydride and the like and the diamine compound and the like are reacted in the solvent is not particularly limited as long as the reaction proceeds, but is usually 0 ° C. or higher, preferably 20 ° C. or higher, and is usually used. It is 120 ° C. or lower, preferably 100 ° C. or lower.
The reaction time is usually 1 hour or more, preferably 2 hours or more, usually 100 hours or less, preferably 42 hours or less.
By carrying out under such conditions, a polyimide precursor tends to be obtained at low cost and in good yield.
The pressure during the reaction may be normal pressure, pressurization or depressurization.
The reaction atmosphere may be under air or under an inert atmosphere.

The solvent used when reacting the tetracarboxylic dianhydride or the like with the diamine compound or the like is not particularly limited. Examples of the reaction solvent include hydrocarbon solvents such as hexane, cyclohexane, heptane, benzene, toluene, xylene, mecitylene, and anisole; carbon tetrachloride, methylene chloride, chloroform, 1,2-dichloroethane, chlorobenzene, dichlorobenzene, and fluoro. Halogened hydrocarbon solvent such as benzene; Ether solvent such as diethyl ether, tetrahydrofuran, 1,4-dioxane, methoxybenzene; Ketone solvent such as acetone, methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone; ethylene glycol monomethyl ether, ethylene glycol Glycol-based solvents such as monoethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether and propylene glycol monomethyl ether acetate; amide-based solvents such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidone; dimethyl Sulphonic solvents such as sulfoxide; heterocyclic solvents such as pyridine, picolin, lutidine, quinoline, isoquinoline; phenolic solvents such as phenol and cresol; lactone solvents such as γ-butyrolactone, γ-valerolactone and δ-valerolactone ; Etc. can be mentioned. One of these solvents may be used alone, or two or more of these solvents may be used in any ratio and combination.

Of these solvents, the preferred solvent will be described later.

The obtained polyimide precursor may be used as it is for the next imidization, or may be added to a poor solvent to precipitate it in a solid state before use.

The poor solvent to be used is not particularly limited and may be appropriately selected depending on the type of polyimide precursor. Examples of the poor solvent include ether solvents such as diethyl ether and diisopropyl ether; ketone solvents such as acetone, methyl ethyl ketone, isobutyl ketone and methyl isobutyl ketone; alcohol solvents such as methanol, ethanol and isopropyl alcohol; and the like. Above all, an alcohol solvent is preferable because a precipitate can be efficiently obtained, a boiling point is low, and drying tends to be easy. One of these solvents may be used alone, or two or more of these solvents may be used in any ratio and combination.

(Immidization of polyimide precursor)
A polyimide can be obtained by dehydrating and cyclizing the polyimide precursor obtained by the above method or the like in the presence of a solvent. Imidization can be performed using any of the conventionally known methods. Examples of the imidization method include thermal imidization for thermal cyclization, chemical imidization for chemical cyclization, and the like. These imidization reactions may be carried out individually or in combination of two or more.

<Heating imidization>
Examples of the solvent for heat imidizing the polyimide precursor include the same solvent used in the reaction for obtaining the polyimide precursor. The solvent used for producing the polyimide precursor and the solvent used for producing the polyimide may be the same or different.
The water produced by imidization inhibits the ring closure reaction and may be discharged out of the system.
The concentration of the polyimide precursor at the time of the imidization reaction is not particularly limited, but is usually 1% by mass or more, preferably 5% by mass or more, and usually 70% by mass or less, preferably 40% by mass or less. By adjusting the concentration of the polyimide precursor in this range, it is possible to produce the polyimide precursor with a solution viscosity that is easy to produce and has high production efficiency.

The reaction temperature for imidization is not particularly limited, but is usually 50 ° C. or higher, preferably 80 ° C. or higher, more preferably 100 ° C. or higher, and usually 300 ° C. or lower, preferably 280 ° C. or lower, further preferably 250 ° C. or lower. .. It is preferable to carry out the reaction in this temperature range because the imidization reaction proceeds efficiently and reactions other than the imidization reaction tend to be suppressed.
The pressure during the reaction may be normal pressure, pressurization, or depressurization.
The reaction atmosphere may be under air or under an inert atmosphere.

As an imidization accelerator that promotes imidization, a compound having a function of enhancing nucleophile and electrophile can be added. Examples of the imidization accelerator include trimethylamine, triethylamine, tripropylamine, tributylamine, triethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, triethylenediamine, N-methylpyrrolidin, N-. Tertiary amine compounds such as ethylpyrrolidine, N-methylpiperidine, N-ethylpiperidine, imidazole, pyridine, quinoline, isoquinoline; acetic acid, 4-hydroxyphenylacetic acid, 3-hydroxybenzoic acid, N-acetylglycine, N-benzoylglycine Carboxylic acid compounds such as 3,5-dihydroxyacetophenone, methyl 3,5-dihydroxybenzoate, pyrogallol, methyl gallate, ethyl gallate, polyvalent phenol compounds such as naphthalene-1,6-diol; 2-hydroxypyridine, 3 -Hydroxypyridine, 4-hydroxypyridine, 4-pyridinemethanol, N, N-dimethylaminopyridine, nicotine aldehyde, isonicotin aldehyde, picolin aldehyde, picolin aldehyde oxime, nicotine aldehyde oxime, isonicotin aldehyde oxime, ethyl picolinate, nicotine Ethyl Acid, Ethyl Isonicotinate, Nicotinamide, Isonicotinamide, 2-Hydroxynicotinic Acid, 2,2'-Dipyridyl, 4,4'-Dipyridyl, 3-Methylpyridazine, Kinolin, Isoquinolin, Phenantroline, 1,10- Heterocyclic compounds such as phenanthroline, imidazole, benzimidazole, 1,2,4-triazole; and the like.

Of these, at least one selected from the group consisting of tertiary amine compounds, carboxylic acid compounds and heterocyclic compounds is preferable, and at least one selected from the group consisting of triethylamine, imidazole and pyridine controls the reaction rate. It is more preferable because it tends to be easy. One of these compounds may be used alone, or two or more thereof may be used in any ratio and combination.

The amount of the imidization accelerator used is usually 0.01 mol% or more, preferably 0.1 mol% or more, and further preferably 1 mol% or more, based on the carboxyl group of the polyimide precursor. The amount of the imidization accelerator used is preferably 50 mol% or less, more preferably 10 mol% or less, based on the carboxyl group of the polyimide precursor. When the amount of the imidization accelerator used is within the above range, the imidization reaction tends to proceed efficiently.
The timing of adding the imidization accelerator can be appropriately adjusted, and may be before the start of heating or during heating. Further, it may be added in a plurality of times.

<Chemical imidization>
A polyimide can be obtained by chemically imidizing a polyimide precursor with a dehydration condensing agent in the presence of a solvent.

Examples of the solvent used for chemical imidization include the same solvents as those used for the reaction for obtaining the polyimide precursor described above.

Examples of the dehydration condensing agent include N, N-2 substituted carbodiimides such as N, N-dicyclohexylcarbodiimide and N, N-diphenylcarbodiimide; acid anhydrides such as acetic anhydride and trifluoroacetic anhydride; thionyl chloride, tosyl chloride and the like. Chloride; acetyl chloride, acetyl bromide, propionyl iodide, acetyl fluoride, propionyl chloride, propionyl bromide, propionyl iodide, propionyl fluoride, isobutyryl chloride, isobutyryl bromide, isobutyryl iodide, isobuchi Lilfluoride, n-butyryl chloride, n-butyryl bromide, n-butyryl iodide, n-butyryl fluoride, mono-, di-, tri-chloroacetyl chloride, mono-, di-, tri- Bromoacetyl chloride, mono-, di-, tri-iodoacetyl chloride, mono-, di-, tri-fluoroacetyl chloride, chloroacetic anhydride, phenylphosphonic dichloride, thionyl chloride, thionyl bromide, thionyliodide, thionylfluo Halogen compounds such as rides; phosphorus compounds such as phosphorus trichloride, triphenyl phosphite, and diethyl phosphate cyanide; and the like.

Among these, acid anhydrides and halogenated compounds are preferable, and acid anhydrides are more preferable because the amount of chlorine is reduced and the imidization reaction tends to proceed efficiently. One of these compounds may be used alone, or two or more thereof may be used in any ratio and combination.

The amount of these dehydration condensing agents used is usually 0.1 mol or more, preferably 0.2 mol or more, and usually 1.6 mol or less, preferably 1.0 mol or less, with respect to 1 mol of the polyimide precursor. By setting the amount of the dehydration condensing agent used within this range, imidization can be performed efficiently.

The concentration of the polyimide precursor in the reaction solution during the imidization reaction is not particularly limited, but is usually 1% by mass or more, preferably 5% by mass or more, and usually 70% by mass or less, preferably 40% by mass or less. .. By setting the concentration of the polyimide precursor in the range, the production efficiency can be increased, and the solution viscosity tends to be easy to produce.

The imidization reaction temperature is not particularly limited, but is usually 0 ° C. or higher, preferably 10 ° C. or higher, and more preferably 20 ° C. or higher. Further, it is usually 150 ° C. or lower, preferably 130 ° C. or lower, and more preferably 100 ° C. or lower. It is preferable to carry out the reaction in this temperature range because the imidization reaction tends to proceed efficiently. Further, it is preferable because side reactions other than the imidization reaction are suppressed.
The pressure during the reaction may be normal pressure, pressurization or depressurization.
The reaction atmosphere may be under air or under an inert atmosphere.

As a catalyst for promoting imidization, an imidization accelerator such as the above-mentioned tertiary amine compound can be added in the same manner as for heat imidization.

<< Method of producing polyimide from tetracarboxylic dianhydride, etc. and diamine compound, etc. >>
Polyimide can be directly obtained from a tetracarboxylic dianhydride or the like and a diamine compound or the like by using a conventionally known method. This method involves the synthesis and imidization of the poimide precursor, and the imidization without stopping the reaction or isolating the precursor.

The order and method of adding the tetracarboxylic dianhydride and the like and the diamine compound and the like are not particularly limited. For example, the tetracarboxylic dianhydride and the like and the diamine compound and the like are added in order to the solvent, and the reaction up to imidization Polyimide can be obtained by stirring at a temperature at which

The amount of the diamine compound or the like is usually 0.7 mol or more, preferably 0.8 mol or more, usually 1.3 mol or less, preferably 1.2 mol or less, relative to 1 mol of the tetracarboxylic dianhydride or the like. By setting the amount of the diamine compound or the like in such a range, the yield of the obtained polyimide tends to be improved.

The concentrations of the tetracarboxylic dianhydride and the like and the diamine compound and the like in the reaction solution can be appropriately set according to each condition and the viscosity during the polymerization.
The total concentration of the tetracarboxylic dianhydride and the like and the diamine compound and the like in the reaction solution is not particularly set, but is usually 1% by mass or more, preferably 5% by mass or more, and usually 70% by mass or less, preferably 40. It is mass% or less. When the concentration in the reaction solution is in an appropriate range, the molecular weight tends to be extended and stirring tends to be easy.

Examples of the solvent used in this reaction include the same solvents used in the reaction for obtaining the polyimide precursor described above.

When the polyimide is obtained from a tetracarboxylic dianhydride or the like and a diamine compound or the like, heat imidization and / or chemical imidization can be adopted as in the case of obtaining a polyimide from a polyimide precursor. The reaction conditions for heat imidization and chemical imidization in this case are the same as described above.

The obtained polyimide may be used as it is, or may be added to a poor solvent to precipitate the polyimide into a solid state, and then redissolved in another solvent to be used as a polyimide composition.

The poor solvent at this time is not particularly limited and can be appropriately selected depending on the type of polyimide. Examples of the poor solvent include ether solvents such as diethyl ether and diisopropyl ether; ketone solvents such as acetone, methyl ethyl ketone, isobutyl ketone and methyl isobutyl ketone; alcohol solvents such as methanol, ethanol and isopropyl alcohol; and the like. .. Above all, an alcohol solvent such as isopropyl alcohol is preferable because a precipitate can be efficiently obtained, the boiling point is low, and drying tends to be easy. One of these solvents may be used alone, or two or more of these solvents may be used in any ratio and combination.

Examples of the solvent for redissolving polyimide include hydrocarbon solvents such as hexane, cyclohexane, heptane, benzene, toluene, xylene, mecitylene, and anisole; N, N-dimethylformamide, N, N-dimethylacetamide, and N-methyl. -Amid solvent such as pyrrolidone; Aproton solvent such as dimethyl sulfoxide; Glycol solvent such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate; chloroform, Examples thereof include halogen-based solvents such as methylene chloride and 1,2-dichloroethane. One of these solvents may be used alone, or two or more of these solvents may be used in any ratio and combination.

[Mechanical properties of polyimide]
The tensile strength of the polyimide of the present invention is not particularly limited, but is usually 50 MPa or more, preferably 70 MPa or more, more preferably 100 MPa or more, still more preferably 150 MPa or more in measurement at 23 ° C. and 50% humidity. The tensile strength of the polyimide of the present invention is preferably 400 MPa or less, more preferably 300 MPa or less.

The tensile elastic modulus of the polyimide of the present invention is not particularly limited, but is usually 1500 MPa or more, preferably 1800 MPa or more, more preferably 2000 MPa or more, and particularly preferably 3000 MPa or more in measurement at 23 ° C. and 50% humidity. The tensile elastic modulus of the polyimide of the present invention is preferably 20 GPa or less, more preferably 10 GPa or less.

The tensile elongation of the polyimide of the present invention is not particularly limited, but is usually 10% GL or more, preferably 20% GL or more, and more preferably 50 GL% or more in the measurement at 23 ° C. and 50% humidity. The tensile elongation of the polyimide of the present invention is preferably 400% GL or less, more preferably 300% GL or less.

It is preferable that the polyimide has mechanical properties in such a range, so that a molded product having higher durability can be obtained.

[Solvent solubility of polyimide]
The solvent solubility of the polyimide of the present invention is not particularly limited, but it is preferably dissolved in an aprotic polar solvent at room temperature (25 ° C.) in an amount of 5% by mass or more, and this solubility is more preferably 10% by mass. The above is more preferably 15% by mass or more, and most preferably 20% by mass or more. Further, there is no upper limit to the solubility, and it is preferable that the solubility is high, but it is usually 80% by mass or less.
When the solvent solubility is in this range, the manufacturability is improved and the process compatibility such as coating is improved, which is preferable.

Here, examples of the aprotic polar solvent include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyl lactone and the like. One of these solvents may be used alone, or two or more of these solvents may be used in any ratio and combination.

[Film manufacturing method]
A film (polyimide film) can be produced using the polyimide of the present invention. The production method is not particularly limited, and for example, it can be produced by applying a polyimide composition in which the polyimide of the present invention is dissolved in a solvent to a substrate by a casting method or the like.

<Polyimide composition>
The content of polyimide in the polyimide composition is not particularly limited, and can be appropriately adjusted according to the production process and the like. The content of polyimide in the polyimide composition is preferably 5% by mass or more, more preferably 10% by mass or more, preferably 70% by mass or less, and more preferably 60% by mass or less. When the polyimide content is in this range, film formation and handling in ordinary equipment are easy, which is preferable.

<< Solvent >>
The polyimide composition of the present invention contains a solvent. The solvent used in the polyimide composition of the present invention is not particularly limited, but the absolute value of the difference between the solubility parameter of the solvent and the solubility parameter based on the repeating unit of the polyimide is preferably 2 or more.

When a film is formed using a polyimide composition, the polyimide molecules interact with each other, and when the polyimide molecules are stacked and oriented, the obtained polyimide film has high performance, high elastic modulus, and excellent bending resistance. There is a tendency. When the difference between the solubility parameter of the solvent and the solubility parameter based on the repeating unit of the polyimide is within a specific range, the polyimide molecules are dried while being oriented during film formation, and a polyimide film having good elastic modulus and bending resistance can be obtained. Tends to be possible.

The absolute value of the difference between the solubility parameters (hereinafter, may be referred to as SP value) is more preferably 2.1 or more, and further preferably 2.5 or more. Further, the absolute value of the difference between the SP values is preferably 10 or less, and more preferably 8 or less. When the absolute value of the difference in SP value is equal to or more than the above lower limit value, the solubility in a solvent does not become excessive, the stacking and compounding of polyimide molecules proceed during the film formation of the polyimide film, and the elastic modulus and bending resistance are excellent. There is a tendency to obtain a polyimide film. When the absolute value of the difference between the SP values is not more than the above upper limit value, the solubility of the polyimide in the solvent is improved, and the uniformity of the obtained film, the surface smoothness, and the like tend to be excellent.

In the present invention, the solubility parameter (SP value) is Hansen's solubility parameter (HSP), which is an index showing the solubility of a substance in another substance. The SP value is a three-dimensional space obtained by dividing the solubility parameter introduced by Hildebrand into three components of the dispersion term δD, the polarity term δP, and the hydrogen bond term δH. The dispersion term δD indicates the effect due to the dispersion force, the polar term δP indicates the effect due to the dipole force, and the hydrogen bond term δH indicates the effect due to the hydrogen bond force.
δD: Energy derived from intermolecular dispersion force δP: Energy derived from intermolecular polar force δH: Energy derived from intermolecular hydrogen bonding force (Here, each unit is MPa ^0. It is ^5. ).
Definitions and calculations of SP values are described in the literature below.
Charles M. Hansen, Hansen Solubility Parameters: A Users Handbook (CRC Press, 2007).

The dispersion term reflects the van der Waals force, the polarity term reflects the dipole moment, and the hydrogen bond term reflects the action of water, alcohol, etc. Then, it can be determined that the vectors having similar SP values have high solubility, and the degree of similarity of the vectors can be determined by the absolute value of the difference between the SP values. Further, the SP value can be an index not only for determining the solubility but also for determining how easily a certain substance is present in another substance, that is, how good the dispersibility is.

In the present invention, the SP value [δD, δP, δH] can be easily estimated from its chemical structure by using, for example, the computer software Hansen Solubility Parameter in Practice (HSPiP). Specifically, it is obtained from the chemical structure by the Y-MB method implemented in HSPiP. When the chemical structure is unknown, it can be obtained by the sphere method implemented in HSPiP from the results of dissolution tests using a plurality of solvents.

Absolute value of the difference between the SP value, for example, the SP value of solute (SP value based on the repeating unit of the polyimide in the present _{invention) (δD 1, δP 1,} δH 1) and then, the SP value of the solvent ([delta] D _2, [delta] P _{When 2} , δH ₂ ), it can be calculated by the following formula.
SP value of the absolute value of the difference _{= {(δD 1 -δD 2)} 2 + (δP 1 -δP 2) 2 + (δH 1 -δH 2) 2} 0.5

In the present invention, the SP value based on the repeating unit of polyimide is the SP value of the structure in which the raw material monomer of polyimide is reacted one molecule at a time, and when the polyimide contains two or more kinds of repeating units, each repetition is performed. It is calculated proportionally from the content ratio of the unit.
Similarly, when two or more kinds of mixed solvents are used for the solvent and the production solvent described later, the SP value of the mixed solvent can be obtained by proportional calculation from the SP value of each solvent and the usage ratio thereof.

As the solvent, various solvents can be mentioned as described later, but from the viewpoint of lowering the drying temperature at the time of film formation, a solvent having a low boiling point is preferable, and methylene chloride (SP value 19.8) is particularly preferable. Therefore, in the polyimide of the present invention, it is preferable that the SP value based on the repeating unit satisfies the above relationship with respect to the SP value of methylene chloride.
That is, the polyimide of the present invention is usually 21.8 or more, preferably 21.9 or more, more preferably 22 when the value of (SP value based on the repeating unit of polyimide)-(SP value of methylene chloride) is positive. It is 0.3 or more, preferably 29.8 or less, and more preferably 27.8 or less. When this value is negative, it is usually 17.8 or less, preferably 17.7 or less, more preferably 17.3 or less, 9.8 or more, and more preferably 11.8 or more.

On the other hand, if the polyimide has low solubility in the reaction solvent used in the production of the polyimide (hereinafter, may be referred to as "production solvent"), it will be precipitated during the production, which is the target. There is a risk that polyimide cannot be manufactured.
Therefore, the polyimide of the present invention preferably has a certain degree of solubility in the production solvent, that is, the SP value is close to each other. From this viewpoint, the production solvent is obtained from the SP value based on the repeating unit of the polyimide of the present invention. The value obtained by subtracting the SP value of is preferably −3.0 or higher, particularly −1.0 or higher, particularly 0.0 or higher, and 5.0 or lower, particularly 4.0 or lower, particularly 3.0 or lower. Is preferable.

As described above, various solvents for producing polyimide can be mentioned, but from the viewpoint of production stability and susceptibility to molecular weight elongation, dimethylacetamide (DMAc) (SP value 23) and N-methyl-2-pyrrolidone ( It is preferable to use NMP) (SP value 23). Therefore, the SP value based on the repeating unit of the polyimide of the present invention is preferably 20 or more, particularly 21 or more, particularly 23 or more, and 28 or less, particularly 27 or less, particularly 26 or less.

The polyimide composition may contain other components in addition to the polyimide and the solvent.
Other components include, for example, surfactants, antioxidants, lubricants, colorants, stabilizers, UV absorbers, antistatic agents, flame retardants, plasticizers, mold release agents, leveling agents, defoamers, etc. Can be mentioned. In addition, if necessary, an inorganic filler or an organic filler such as powder, granular, plate, or fibrous may be blended as long as the object of the invention is not impaired.
These additive components may be added at any stage of any process for producing the polyimide precursor and / or the polyimide composition.

<< Surfactant >>
The polyimide composition of the present invention may contain a surfactant. The inclusion of a surfactant tends to improve the solubility of polyimide in a solvent.
Examples of the surfactant include a cationic surfactant, an anionic surfactant, an amphoteric surfactant, a nonionic surfactant and the like. The surfactant may be used alone or in combination of two or more.

Specific examples of the cationic surfactant used in the present invention include amine type and quaternary ammonium salt type.
Examples of the amine type include aliphatic amines such as polyoxyethylene alkylamines and alkylamine salts, and heterocyclic amine salts such as alkylimidazolines.
The quaternary ammonium salt type includes alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkylbenzyldimethylammonium salt, polydiallyldimethylammonium salt; chlorine salt type such as alkyltrimethylammonium chloride and dialkyldimethylammonium chloride; alkyldimethylethylammonium. Non-chlorine type such as ethyl sulfate; and the like.

Specific examples of the anionic surfactant used in the present invention include sulfate ester type, phosphoric acid ester type, carboxylic acid type, and sulfonic acid type.
Specific examples of the sulfate ester type include alkyl sulfate ester, ethoxy sulfate ester, polyoxyethylene styrene phenyl sulfate ester, polyoxyethylene alkyl ether sulfate ester, long-chain alcohol sulfate ester, other sulfate esters, and salts thereof. Can be mentioned.
Specific examples of the phosphoric acid ester type include polyoxyethylene alkyl ether phosphoric acid esters and salts thereof.
Specific examples of the carboxylic acid type include fatty acids, polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl ether sulfosuccinic acid, alkenyl succinic acid, polyacrylic acid, styrene-maleic acid copolymer ammonium, carboxymethyl cellulose, polyacrylic acid, and polycarboxylic acid. Acids and salts thereof may be mentioned.
Specific examples of the sulfonic acid type include sulfonic acid, sulfosuccinic acid, alkylbenzene sulfonic acid, alkane sulfonic acid, alpha olefin sulfonic acid, phenol sulfonic acid, sodium naphthalene sulfonic acid formalin condensate, and salts thereof.

Specific examples of the amphoteric surfactant used in the present invention include betaine type, amine oxide type, N-alkylamino acid type and imidazoline type.
Specific examples of the betaine type include alkyl betaine, amide betaine such as aliphatic amide betaine, and the like.
Specific examples of the amine oxide type include alkylamine oxides and the like.
Specific examples of the N-alkyl amino acid type include N-alkyl-β-aminopropionate.
Specific examples of the imidazoline type include 2-alkylimidazoline derivatives.

Specific examples of the nonionic surfactant used in the present invention include ether type, ester type, ether ester type, polyhydric alcohol type, amide type, and polymer type.
Specific examples of the ether type include polyoxyalkylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, and polyoxyethylene alkyl amine.
Examples of the ester type include sorbitan fatty acid ester, glycerin fatty acid ester, sucrose fatty acid ester, sucrose derivative, and fatty acid ester.
Examples of the ether ester type include polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene fatty acid ester, and polyoxyethylene hydrogenated castor oil ether.
Examples of the polyhydric alcohol type include alkyl glucosides and alkyl polyglucosides.
Specific examples of the amide type include alkylalkanolamides.
Specific examples of the polymer type include polyvinylpyrrolidone, a polyalkylene polyamine alkylene oxide adduct, and a polyalkylene polyimine alkylene oxide adduct.

Specific examples of the nonionic surfactant include polyoxyethylene alkyl ethers such as Emargen 123P, Emargen 130K, Emargen 150, Emargen 430, Emargen 409PV, Emargen 705, Emargen 707, and Emargen 709 (manufactured by Kao); Sorbitane fatty acid esters such as (Daiichi Kogyo Seiyaku Co., Ltd.), New Coal 20, New Coal 60, and New Coal 80 (manufactured by Nippon Emulsifier); Examples thereof include sucrose fatty acid esters such as DK ester F-110 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) and polyvinylpyrrolidone such as Pittscol K-30 and Pittscol K-40 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.).

Among the above, it is preferable to use a nonionic surfactant. By using a nonionic surfactant, the solubility of polyimide in a solvent tends to be improved.

<< Leveling agent >>
The polyimide composition of the present invention may contain a leveling agent. The inclusion of the leveling agent tends to improve the smoothness of the obtained polyimide film.
Examples of the leveling agent include silicone compounds and the like. The silicone-based compound is not particularly limited, and for example, polyether-modified siloxane, polyether-modified polydimethylsiloxane, polyether-modified hydroxyl group-containing polydimethylsiloxane, polyether-modified polymethylalkylsiloxane, polyester-modified polydimethylsiloxane, and polyester-modified hydroxyl group. Examples thereof include polydimethylsiloxane contained, polyester-modified polymethylalkylsiloxane, aralkyl-modified polymethylalkylsiloxane, highly polymerized silicone, amino-modified silicone, amino derivative silicone, phenyl-modified silicone, and polyether-modified silicone. One of these may be used alone, or two or more thereof may be used in any ratio and combination.

<Film formation method>
The film forming method of the polyimide film using the above-mentioned polyimide composition is sometimes not limited, and examples thereof include a method of applying the polyimide composition to a substrate or the like.

Examples of the coating method include die coating, spin coating, dip coating, screen printing, spraying, casting method (single leaf method and continuous method), method using a coater, coating method by spraying, dipping method, calendar method and the like. .. These methods can be appropriately selected depending on the coated area, the shape of the surface to be coated, and the like.
Of these, since the uniformity of the coating film thickness is good and the surface smoothness tends to be good, it is preferable to adopt a casting method or a method using a coater, and it is more preferable to use the casting method.

There is no particular limitation on the method of volatilizing the solvent contained in the film formed by coating or the like. Usually, the solvent is volatilized by heating the film formed by coating or the like. The heating method is not particularly limited, and examples thereof include hot air heating, vacuum heating, infrared heating, microwave heating, and heating by contact using a hot plate / hot roll or the like.

As the heating temperature when the solvent is volatilized, a suitable temperature can be used depending on the type of solvent. The heating temperature is usually above the boiling point of the solvent, preferably above the boiling point of the solvent + 50 ° C, more preferably above the boiling point of the solvent + 100 ° C, usually below the boiling point of the solvent + 200 ° C, preferably above the boiling point of the solvent + 180 ° C. Hereinafter, the boiling point of the solvent is more preferably + 150 ° C. or lower. When the heating temperature is in the above range, the solvent is preferably sufficiently volatilized.

The polyimide film of the present invention can be obtained, for example, by applying a polyimide composition containing the polyimide of the present invention and a casting solvent to a support as described above, heating the support, and peeling the film from the support.

The method of peeling the polyimide film from the support is not particularly limited, but a physical peeling method or a laser peeling method is preferable in that the polyimide film can be peeled off without impairing the performance of the film or the like.

Examples of the method of physically peeling include a method of obtaining a polyimide film by cutting off the peripheral edge of a laminate made of a polyimide film / support, a method of sucking the peripheral edge portion to obtain a polyimide film, and a method of fixing the peripheral edge and supporting a base material. A method of obtaining a polyimide film by moving the film can be mentioned.

The thickness of the polyimide film of the present invention thus obtained is usually 1 μm or more, preferably 2 μm or more, and usually 300 μm or less, preferably 200 μm or less. When the thickness is 1 μm or more, the polyimide film can obtain sufficient strength and can be obtained as a self-supporting film, and the handleability tends to be improved. Further, by setting the thickness to 300 μm or less, the uniformity of the film tends to be easily ensured.

[Laminate]
The polyimide film of the present invention can also be used as a laminate. For example, on the polyimide film of the present invention, a hard coat layer having a function of imparting scratch resistance, abrasion resistance, etc., a layer having a function of imparting optical compensation, etc., an adhesive layer, and the like can be provided. The same or different layers may be provided on both sides of the polyimide film of the present invention.

The polyimide film of the present invention has a high surface hardness, excellent bending resistance, high light transmittance, elastic modulus, flexibility, transparency, high solvent solubility, and high device applicability. It is useful as a cover film for. In this application, it can be used as a laminate having a hard coat layer on the polyimide film of the present invention.

The hard coat layer can be formed directly on the polyimide film or through an adhesive layer or the like.
The hard coat layer is not particularly limited and can be formed by using a commonly used hard coat agent. Examples of the hard coating agent include curable resins such as light and heat, inorganic materials, and curable resins containing inorganic materials. The forming method can be selected according to each material. Further, a defoaming agent, a leveling agent, a thickener, an antistatic agent, an antifogging agent and the like may be appropriately added to the hard coating agent, if necessary.

The thickness of the hard coat layer is not particularly limited, but is preferably 50 μm or more, and more preferably 60 μm or more. The thickness of the hard coat layer is preferably 200 μm or less, and preferably 180 μm or less. When the thickness of the hard coat layer is within this range, it tends to be excellent in high surface hardness and bending resistance.

The pencil hardness of the surface of the hard coat layer in the laminate of the present invention is not particularly limited, but is preferably B or higher, more preferably F or higher, still more preferably H or higher, and particularly preferably 2H or higher.

Especially when the laminate is used for light transmission such as display applications, it is desirable that the polyimide film / hard coat layer laminate has high transparency. The YI (yellowness) of the laminate of the present invention is not particularly limited, but is preferably 3 or less, more preferably 2.8 or less, and further preferably 2 or less.

The haze of the laminate of the present invention is not particularly limited, but is preferably 3% or less, more preferably 2% or less, still more preferably 1.5% or less, and particularly preferably less than 1%.

The present invention will be described in more detail below by way of examples. The following examples are shown for explaining the present invention in detail, and the present invention is not limited to the following examples unless contrary to the gist thereof.

[Solubility test]
The polyimide was dissolved in N, N-dimethylacetamide (DMAc) at 25 ° C. at a concentration of 20% by mass, visually confirmed, and if all were dissolved (completely dissolved), 〇, if not completely dissolved. Was x.

[Film molding]
A solution prepared by dissolving polyimide in DMAc at a concentration of 20% by mass was applied to a soda glass substrate using a 500 μm applicator, and dried at 260 to 330 ° C. for 30 minutes. Then, it was peeled off from the glass substrate to obtain a polyimide film having a thickness of 50 μm.
The drying temperatures in each Example and Comparative Example are as shown in Table 1.

[Dynamic Viscoelasticity Measurement (DMS)]
Using a dynamic viscoelastic analyzer (SII6100 manufactured by Hitachi High-Tech Science Co., Ltd.), a polyimide film having a width of 6 mm and a length of 20 mm was measured in a temperature range of room temperature to 430 ° C. at a frequency of 10 Hz and a heating rate of 5 ° C./min. .. The value of the curve plotting the storage elastic modulus with respect to temperature at 25 ° C. was obtained as the elastic modulus at room temperature.

[Flexibility evaluation]
Using a MIT tester, a polyimide film having a width of 15 mm and a length of 110 mm was bent at a bending radius of 0.38 mm and a speed of 175 times / min, and evaluated as the number of reciprocating bends until the test piece broke.

[Yellow index (YI) evaluation]
Using a color computer manufactured by Suga Seiki Co., Ltd., it was evaluated as a yellow index (YI) per 50 μm thickness of the polyimide film.

[Amount of chlorine in 1 g of polyimide)]
The polyimide was collected on a magnetic board and heated in a quartz tube furnace (AQF-100 type manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and the chlorine content in the combustion gas was absorbed by the H ₂ O ₂ aqueous solution. Cl ⁻ in the absorption liquid was measured by an ion chromatograph (ICS-1600 type manufactured by Thermo Fisher Scientific Co., Ltd.). Since the raw materials and manufacturing methods of Example 2 are the same as those of Example 1 and Examples 4 and 5 are the same as those of Example 3, the amount of chlorine is estimated to be about the same, although the measurement has not been performed.

[Solubility parameter (SP value)]
HSPiP ver. Calculation was performed using 4.1.05 and using a structure formed when one molecule of tetracarboxylic dianhydride, which is a raw material of polyimide, was reacted with a diamine compound. When two or more kinds of tetracarboxylic dianhydrides and / or diamine compounds were used, they were calculated proportionally using the copolymerization ratio.

[Example 1]
34.0 g of 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride in a four-necked flask equipped with a nitrogen gas introduction tube, a cooler, a Dean-Stark aggregator filled with toluene, and a stirrer. 40.43 g of 4,4'-diamino-2,2'-dimethylbiphenyl, 2.7 g of terephthalic acid dihydrazide, 171 g of NMP, and 26 g of toluene were added, and the mixture was heated under reflux in an oil bath at 190 ° C. for 13 hours. Of the obtained reaction solution, 20 g was diluted 5-fold with DMAc. This solution was added dropwise to 500 mL of isopropanol with stirring at room temperature. The precipitated powder was collected by filtration. The obtained wet cake was placed in 200 mL of isopropanol and stirred at room temperature for 30 minutes. The powder was collected by filtration and dried under reduced pressure at 80 ° C. for 30 minutes and at 150 ° C. for 30 minutes to obtain Polyimide 1.
The obtained polyimide 1 was subjected to a solvent solubility test and a measurement of the amount of chlorine.
The obtained polyimide 1 was film-molded at a drying temperature of 280 ° C. For the obtained polyimide film, dynamic viscoelasticity measurement, flexibility and Y. I. Evaluation was performed.
These results are shown in Table 1.

[Example 2]
340 g of 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride of Example 1, 14.6 g of 4,4'-diamino-2,2'-dimethylbiphenyl, and 8. terephthalic acid dihydrazide. Polyimide 2 was obtained in the same manner as in Example 1 except that 0 g, NMP was changed to 170 g, and toluene was changed to 30 g.
The obtained polyimide 2 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]
Example 1 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride to 37.1 g, 4,4'-diamino-2,2'-dimethylbiphenyl to 19.1 g, terephthalic acid Polyimide 3 was obtained in the same manner as in Example 1 except that dihydrazide was changed to 5.8 g of isophthalic acid dihydrazide, NMP was changed to 186 g, and toluene was changed to 37.2 g.
The obtained polyimide 3 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 4]
3,3', 4,4'-biscyclohexanetetracarboxylic acid dianhydride 25.5 g, 2,2'in a four-necked flask equipped with a nitrogen gas introduction tube, a cooler, a Dean-Stark aggregator, and a stirrer. -Bis (trifluoromethyl) -4,4'-diaminobiphenyl 13.2 g, isophthalic acid dihydrazide 8.0 g, NMP 109 g, xylene 72.4 g were added, heated and stirred in an oil bath at 80 ° C for 1 hour, and then 200 ° C. The mixture was heated under reflux for 13 hours in the oil bath of. Polyimide 4 was obtained from the obtained reaction solution in the same manner as in Example 1.
The obtained polyimide 4 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 5]
30.9 g of 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride and 24.0 g of 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl of Example 4. Polyimide 5 was obtained in the same manner as in Example 4 except that isophthalic acid dihydrazide was changed to 4.9 g of terephthalic acid dihydrazide, NMP was changed to 140 g, and xylene was changed to 92.7 g.
The obtained polyimide 5 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 6]
36.6 g of 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride in a four-necked flask equipped with a nitrogen gas introduction tube, a cooler, a Dean-Stark aggregator filled with toluene, and a stirrer. 19.1 g of 4,4'-diamino-2,2'-dimethylbiphenyl, 5.8 g of terephthalic acid dihydrazide, 246 g of NMP, and 49.2 g of toluene were added, and the mixture was heated under reflux in an oil bath at 190 ° C. for 13 hours. Of the obtained reaction solution, 20 g was diluted 5-fold with DMAc, and this solution was added dropwise to 500 mL of isopropanol with stirring at room temperature. The precipitated powder was collected by filtration. The obtained wet cake was placed in 200 mL of isopropanol and stirred at room temperature for 30 minutes. The powder was collected by filtration and dried under reduced pressure at 80 ° C. for 30 minutes and at 150 ° C. for 30 minutes to obtain polyimide 6.
The SP value of the obtained polyimide 6 was calculated to be 27.4. Therefore, the absolute value of the difference in SP value from methylene chloride (19.8) is 7.6, and the difference in SP value from dimethylacetamide (DMAc) (SP value 23) is 4.4.
A film was formed using the obtained polyimide 6, and the elastic modulus and bending resistance of the obtained polyimide film were evaluated, and the results are shown in Table 2.

[Example 7]
34.0 g of 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride of Example 6, 20.43 g of 4,4'-diamino-2,2'-dimethylbiphenyl, and dihydrazide terephthalate. Polyimide 7 was obtained in the same manner as in Example 6 except that 2.7 g, NMP was changed to 171 g, and toluene was changed to 26 g.
The SP value of the obtained polyimide 7 was calculated to be 26.4. Therefore, the absolute value of the difference in SP value from methylene chloride (19.8) is 6.6, and the difference in SP value from dimethylacetamide (DMAc) (SP value 23) is 3.4.
A film was formed using the obtained polyimide 7, and the elastic modulus and bending resistance of the obtained polyimide film were evaluated, and the results are shown in Table 2.

[Example 8]
340 g of 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride of Example 6, 14.6 g of 4,4'-diamino-2,2'-dimethylbiphenyl, and 8. terephthalic acid dihydrazide. Polyimide 8 was obtained in the same manner as in Example 6 except that 0 g, NMP was changed to 170 g, and toluene was changed to 30 g.
The SP value of the obtained polyimide 8 was calculated to be 28.3. Therefore, the absolute value of the difference in SP value from methylene chloride (19.8) is 8.5, and the difference in SP value from dimethylacetamide (DMAc) (SP value 23) is 5.3.
A film was formed using the obtained polyimide 8, and the elastic modulus and bending resistance of the obtained polyimide film were evaluated, and the results are shown in Table 2.

[Example 9]
Example 6 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride to 37.1 g, 4,4'-diamino-2,2'-dimethylbiphenyl to 19.1 g, terephthalic acid Polyimide 9 was obtained in the same manner as in Example 6 except that dihydrazide was changed to 5.8 g of isophthalic acid dihydrazide, NMP was changed to 186 g, and toluene was changed to 37.2 g.
The SP value of the obtained polyimide 9 was calculated to be 27.2. Therefore, the absolute value of the difference in SP value from methylene chloride (19.8) is 7.4, and the difference in SP value from dimethylacetamide (DMAc) (SP value 23) is 4.2.
A film was formed using the obtained polyimide 9, and the elastic modulus and bending resistance of the obtained polyimide film were evaluated, and the results are shown in Table 2.

[Example 10]
3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride 25.5 g, 2,2'in a four-necked flask equipped with a nitrogen gas introduction tube, a cooler, a Dean-Stark aggregator, and a stirrer. -Bis (trifluoromethyl) -4,4'-diaminobiphenyl 13.2 g, isophthalic acid dihydrazide 8.0 g, NMP 109 g, xylene 72.4 g were added, and the mixture was heated and stirred in an oil bath at 80 ° C. for 1 hour, and then heated to 200 ° C. The mixture was heated under reflux in an oil bath for 13 hours. The obtained reaction solution was used in the same manner as in Example 5 to obtain Polyimide 10.
The SP value of the obtained polyimide 10 was calculated to be 28.2. Therefore, the absolute value of the difference in SP value from methylene chloride (19.8) is 8.4, and the difference in SP value from dimethylacetamide (DMAc) (SP value 23) is 5.2.
A film was formed using the obtained polyimide 10, and the elastic modulus and bending resistance of the obtained polyimide film were evaluated, and the results are shown in Table 2.

[Example 11]
30.9 g of 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride and 24.0 g of 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl of Example 8. Polyimide 11 was obtained in the same manner as in Example 10 except that isophthalic acid dihydrazide was changed to 4.9 g of terephthalic acid dihydrazide, NMP was changed to 140 g, and xylene was changed to 92.7 g.
The SP value of the obtained polyimide 11 was calculated to be 26.0. Therefore, the absolute value of the difference in SP value from methylene chloride (19.8) is 6.2, and the difference in SP value from dimethylacetamide (DMAc) (SP value 23) is 3.0.
A film was formed using the obtained polyimide 11, and the elastic modulus and bending resistance of the obtained polyimide film were evaluated, and the results are shown in Table 2.

[Comparative Example 1]
In Example 1, 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride was added to 42.5 g, and 4,4'-diamino-2,2'-dimethylbiphenyl was added to 2,2'-bis. (Trifluoromethyl) -4,4'-diaminobiphenyl 33.6 g, terephthalic acid dihydrazide to 4,4'-diaminobenzanilide 8.0 g, NMP to 252 g, toluene to 50.4 g Polyimide 12 was obtained in the same manner as in Example 1.
The obtained polyimide 12 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
In Example 1, 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride was added to 31.8 g, and 4,4'-diamino-2,2'-dimethylbiphenyl was added to 2,2'-bis. (Trifluoromethyl) -4,4'-diaminobiphenyl 26.9 g, terephthalic acid dihydrazide to 1,4'-diaminobenzanilide 12.7 g, NMP to 245 g, toluene to 49.0 g, 3 , 3', 4,4'-biphenyltetracarboxylic dianhydride 10.2 g was added in the same manner as in Example 1 to obtain a polyimide 13.
Since the obtained polyimide 13 had poor solvent solubility and it was difficult to form a polyimide film, no evaluation other than solvent solubility was performed.

[Comparative Example 3]
16.0 g of 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride in a four-necked flask equipped with a nitrogen gas introduction tube, a cooler, a Dean-Stark aggregator filled with toluene, and a stirrer. 1,4.9 g of 4,4'-diamino-2,2'-dimethylbiphenyl, 92 g of NMP, and 18.4 g of toluene were added, and the mixture was heated under reflux in an oil bath at 190 ° C. for 7 hours. To the obtained reaction solution, 3.5 g of terephthalic acid chloride, 3.5 g of triethylamine and 5 g of NMP were added, and the mixture was heated and stirred at 80 ° C. for 4 hours. From the obtained reaction solution, polyimide 14 was obtained in the same manner as in Example 1.
The obtained polyimide 14 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 4]
Polyimide 15 was obtained in the same manner as in Comparative Example 3 except that the terephthalic acid chloride of Comparative Example 3 was changed to 5.1 g of 4,4'-oxybis (benzoyl) chloride.
The obtained polyimide 15 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

The terms used in Table 1 are as follows.
HBPDA: 3,3', 4,4'-biscyclohexanetetracarboxylic dianhydride m-TB: 4,4'-diamino-2,2'-dimethylbiphenyl 6F-m-TB: 2,2'-bis (Trifluoromethyl) -4,4'-diaminobiphenyl TPDH: terephthalic acid dihydrazide TPC: terephthalic acid chloride IPDH: isophthalic acid dihydrazide ODBC: 4,4'-oxybis (benzoyl) chloride BPDA: 3,3', 4,4 '-Biphenyltetracarboxylic dianhydride DABA: 4,4'-diaminobenzanilide

In Table 1, the introduction amount (mol%) of the structure represented by the general formula (1) in the polyimide as the concentration of the amide bond with respect to the imide ring of the main chain is described as "structure (1) ratio".
The structure (1) ratio in Table 1 is a value obtained by calculation from the usage ratio of the raw material compound used, but it is considered that the difference from the analysis value by the above-mentioned analysis method is small.

From Table 1, it can be seen that the polyimide of the present invention has high light transmittance, elastic modulus, flexibility, transparency, and high solvent solubility.
On the other hand, Comparative Example 1 had a low elastic modulus, and Comparative Example 2 had difficulty in film formation. Comparative Examples 3 and 4 have a large amount of chlorine, low device applicability, and Y. I. The value is high.

From Table 2, it can be seen that the polyimide film using the polyimide having a specific SP value has a high elastic modulus and excellent bending resistance.

Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the intent and scope of the invention.
This application is a Japanese patent application filed on March 19, 2019, 2019-051099, a Japanese patent application filed on August 26, 2019, 2019-153992, and Japan filed on August 26, 2019. It is based on patent application 2019-153988, which is incorporated by reference in its entirety.

Claims (13)

1. A polyimide having a unit derived from a tetracarboxylic dianhydride and a unit derived from a diamine compound, having a structure represented by the following general formula (1), and having a chlorine content of 50 μg or less in 1 g of the polyimide. ..
   

   

   In the general formula (1), R represents at least one selected from the group consisting of a divalent aromatic ring group, a heterocyclic group, an alicyclic group and a chain aliphatic group which may have a substituent. .. * Indicates a bond.
2. The polyimide according to claim 1, which has an aliphatic skeleton as a unit derived from the tetracarboxylic dianhydride.
3. The polyimide according to claim 1 or 2, wherein R of the general formula (1) is at least one selected from the group consisting of a divalent aromatic ring group and a chain aliphatic group.
4. The polyimide according to any one of claims 1 to 3, wherein the structure represented by the general formula (1) includes at least a structure obtained by a reaction of a tetracarboxylic dianhydride and a dihydrazide compound.
5. The polyimide according to any one of claims 1 to 4, which has an elastic modulus of 4 GPa or more at 25 ° C.
6. The polyimide according to any one of claims 1 to 5, which is dissolved in an aprotic polar solvent at 25 ° C. in an amount of 5% by mass or more and 80% by mass or less.
7. The polyimide according to any one of claims 1 to 6, wherein the glass transition temperature is 150 ° C. or higher.
8. The composition containing the polyimide and the solvent according to any one of claims 1 to 7, wherein the absolute value of the difference between the solubility parameter of the solvent and the solubility parameter based on the repeating unit of the polyimide is 2 or more. Composition.
9. A film obtained from the composition according to claim 8.
10. The film according to claim 9, wherein the film thickness is 1 μm or more and 300 μm or less.
11. The film according to claim 9 or 10, wherein the film is obtained by a casting method.
12. A laminate having a hard coat layer on the film according to any one of claims 9 to 11.
13. The laminate according to claim 12, wherein the hard coat layer has a film thickness of 50 μm or more and 200 μm or less.