JP6915251B2 - Polyimide resin composition, method for producing polyimide resin composition, transparent substrate and display film - Google Patents

Description

The present invention relates to a polyimide resin composition, a method for producing a polyimide resin composition, a transparent substrate, and a film for display. More specifically, the present invention is excellent in mechanical properties (elasticity, folding resistance) and suppresses coloring peculiar to polyimide. The present invention relates to the polyimide resin composition obtained, a method for producing the same, and a transparent substrate and a display film containing the polyimide resin composition.

In recent years, heat-resistant transparent polyimide has been developed as a material for foldable devices, transparent FPCs (Flexible Printed Circuits), and the like. However, although transparent and highly elastic resins that can satisfy the physical characteristics (mechanical properties (elastic modulus, folding resistance) and optical properties (light transmittance, YI) required for various devices are being studied, mechanical properties and optics are being studied. At present, we have not yet been able to satisfy the characteristics in terms of characteristics, etc. In addition, we often rely on resin design to make materials that satisfy the desired design, which is disadvantageous in terms of cost. Become.

Generally, a polyimide film used in the fields of electrical and electronic materials, optical materials, paints, etc. is formed by forming a film in the state of polyamic acid, which is a precursor of polyimide, and then heat-sealing (imidizing) the film. It can be roughly divided into a method of obtaining a film and a method of obtaining a film by forming a film using a solvent-soluble polyimide that has been ring-closed in advance by a chemical / thermal reaction. In the former, a polyimide molded product is obtained by simultaneously performing solvent removal and imidization reaction by applying a polyamic acid varnish to the surface of the material to be coated and then heat-treating it. The latter is a molded product made of solvent-soluble polyimide by introducing a flexible molecular chain into the molecular skeleton or introducing a group that increases the distance of the imide ring in the molecule.

As a means for imparting functions such as mechanical properties and heat resistance of the polyimide film and further improving the physical properties, an inorganic additive such as silica or an organic additive and a resin may be mixed and composited.

There are few reports of additives added to rigid and insoluble polyimides, but since polyamic acid, which is a precursor of polyimide, is soluble, it is possible to add additives, and reports using fillers, etc. There are many examples (see, for example, Patent Document 1).
However, the polyamic acid solution has poor storage stability, and the polyamic acid is imidized in the thermoforming temperature range to raise the glass transition temperature and greatly reduce the fluidity of the resin, which makes it difficult to control the manufacturing conditions and productivity. There was a problem that the temperature decreased. Furthermore, when the thermal imidization reaction is carried out from the polyamic acid, a dehydration reaction is involved, so that water molecules are desorbed in the film, the molded body is greatly shrunk, and the film is foamed in the film due to the vaporization of water. There was a problem that the physical properties changed.

As a method for improving the above problems, a method of suppressing foaming due to vaporization of water using a dehydrating agent and a method of performing imidization while suppressing foaming due to water by adjusting the degree of decompression have been proposed. However, organic additives having a low molecular weight are generally removed under reduced pressure conditions such as the removal step of the dehydrating agent used and the reduced pressure condition in which foaming due to water is suppressed. Therefore, as an additive to be added to polyamic acid, it is generally used. Its use has been limited to inorganic additives such as fillers that are difficult to remove and volatilize.

Further, as a method for solving the above problem, there is a method using a solvent-soluble polyimide. When molding using solvent-soluble polyimide, since it has a dehydrated imide structure at the time of molding, there is no water generated by the imidization reaction as described above, and the use of a dehydrating agent and foaming are suppressed. The decompression step for this is not required. Therefore, it is possible to add an organic additive, and there are cases where various improvements in physical properties have been achieved (see, for example, Patent Document 2).
However, in order to make the polyimide soluble in the solvent, (1) _{introduction of linking groups such as -CH 2-} , -O-, and -S- with low polarity and high flexibility, (2) asymmetric structure, It imparts structural features such as introduction of substituents that disturb symmetry and regularity such as isomers and copolymers, and (3) introduction of bulky substituents (steric hindrance groups) in side chains and main chains. There is a need. These are designed to weaken the intermolecular force between polyimides, and greatly reduce the physical properties such as heat resistance and mechanical properties that are the characteristics of polyimides. Therefore, even if solvent-soluble polyimide is used, it is difficult to satisfy the physical characteristics required for various devices.

In addition, ordinary aromatic polyimides are colored deep yellow, and the cause of this coloring is the formation of intermolecular charge transfer complexes and intramolecular charge transfer complexes between electron donor amines and electron acceptor anhydrides. It is said that. In order to satisfy the physical properties of the highly heat-resistant transparent polyimide required for various devices, it is necessary to suppress this coloring property.
In order to suppress this coloring, it is necessary to suppress the formation of charge transfer complexes between and within the molecules of polyimide, and for that purpose, substituents or bending groups that disturb the regularity are introduced, or Aggregation between molecular chains is inhibited by introducing a fluorine compound having a low interacting force, an alicyclic anhydride, or a diamine structure. However, since these have the structural characteristics of the solvent-soluble polyimide, there is a problem that the physical properties such as mechanical properties and heat resistance are greatly deteriorated.

As described above, in the design of polyimide, the physical properties (mechanical properties, optical properties, etc.) required for various devices have a great influence on the molecular skeleton and higher-order structure of the resin, but it is difficult to achieve both with the resin alone. On the other hand, there are examples in which the film is made functional by adding an inorganic additive to the soluble polyamic acid or an organic additive such as an antioxidant or a mechanical property improver to the soluble polyimide. For the reasons mentioned above, no valid example has been reported that satisfies all of them.

By the way, there is polyisoimide as a positional isomer of polyimide, and this polyisoimide has the following partial structure in the molecule. Polyisoimide is produced by reacting at a low temperature when dehydrating from a polyamic acid, and has a plurality of isomers like the polyisoic acid, and therefore has excellent solubility.

Further, the polyisoimide can be made into an energetically stable polyimide by an intramolecular transition (see the reaction formula (1) below) at a temperature of 200 to 300 ° C. Since this reaction is a rearrangement reaction, water is not generated unlike the case where polyamic acid is converted to polyimide. There is also a report that a polyimide resin composition is formed so as not to deteriorate the physical characteristics of the film by utilizing the fact that this water is not generated (see, for example, Patent Document 3). However, Patent Document 3 does not describe any effect of the additive on improving mechanical properties and suppressing coloration.

Japanese Unexamined Patent Publication No. 2016-074895 Japanese Unexamined Patent Publication No. 2006-29909 Japanese Unexamined Patent Publication No. 2012-162619

The present invention has been made in view of the above problems and situations, and a problem to be solved thereof is to provide a polyimide resin composition having excellent mechanical properties and suppressed coloring peculiar to polyimide, and a method for producing the same. .. Furthermore, it is an object of the present invention to provide a transparent substrate containing a polyimide resin composition and a film for a display.

In the process of examining the cause of the above problem in order to solve the above-mentioned problems, the present inventor has a solubility in dichloromethane (100% by mass) or 1,3-dioxolane (100% by mass) at 25 ° C. within a specific range. By containing a polyimide having a certain aromatic portion and a compound A having a partial structure in which the NICS value is within a specific range and having a molecular weight within a specific range , the mechanical properties are excellent and the polyimide is unique. We have found that we can provide a polyimide resin composition in which coloration is suppressed, a method for producing the same, and a transparent substrate and a film for display containing the polyimide resin composition, and have arrived at the present invention.

That is, the above-mentioned problem according to the present invention is solved by the following means.

1. 1. A polyimide resin composition containing polyimide.
Table II of the specification (paragraph [0356]), wherein the solubility at 25 ° C. for dichloromethane (100% by weight) or 1,3-dioxolane (100% by weight) is in the range of 0.01 to 10% by weight. A polyimide prepared from any of the polyisoimides selected from PI1 to PI6, PI8 to PI18 and PI20 to PI39, which are A-2, A-7, A-8, A-11, A-13, A- B-2, B-7, B-11, B-12, B-14, which have an acid anhydride having a structure represented by 15, A-16 or A-19 and the following aromatic hydrocarbon ring group. A diamine having a structure represented by B-16, B-18, B-19, B-22, B-23, B-24, B-25 or B-26, and C- having the following aromatic heterocyclic group. 1. A diamine having a structure represented by C-3, C-7, C-8 or C-9, or D-3, D-7, D-8 or D having the following cyclic aliphatic hydrocarbon group. Polyimide made from polyisoimide made in combination with a diamine having a structure represented by -10, and
NICS value has a partial structure in the range of -15.0～-7.0, and a molecular weight from the following additive 1 additive 10 used as the compound A is in the range of 250 to 10,000 A polyimide resin composition comprising any of the additives of choice.

2 . The polyimide resin composition according to Item 1, wherein the NICS value of the partial structure of the compound A is in the range of -14.0 to -10.0.

3 . The polyimide resin composition according to item 1 or 2 , wherein the polyimide has a partial structure represented by the following general formula (3) in an amount of 20 mol% or more.

(In the general formula (3), X ¹ is a single bond, an oxygen atom, a sulfur atom, an alkylene group, an amide group, a sulfonyl group, an amino group, a sulfide group, a carbonyl group, or a divalent linking group formed by a combination thereof. R ³ and R ⁴ each independently represent a hydrogen atom or a substituent, ^{and when there are a plurality of R 3} and R ⁴ , they may be the same or different. P and q. Represents an integer from 0 to 4, r represents an integer from 0 to 3. Where p or q represents an integer of 1 or more when ^{X 1 is a single coupling and p when r = 0.} Represents an integer greater than or equal to 1.)

4 . The polyimide has an isoimide partial structure represented by the following general formula (A1), a total amount of the imide partial structure represented by the following general formula (A2) and the amic acid partial structure represented by the following general formula (A3) ( to 100 mol%), polyimide resin composition according to any one of the first term, characterized in that it comprises in the range of 0.05～10Mol% to paragraph 3.

(In the general formula (A1) ~ (A3), X 2 and ^{Y 2} each independently represent a substituted or unsubstituted tetravalent aromatic hydrocarbon ring group, aromatic heterocyclic group, the 4-39 carbon atoms Represents an acyclic aliphatic hydrocarbon group or a cyclic aliphatic hydrocarbon group having 4 to 39 carbon atoms, and represents a single bond, an oxygen atom, a sulfur atom, an alkylene group, an amide group, a sulfonyl group, an amino group, a sulfide group, and a carbonyl group. A plurality of aromatic hydrocarbon ring groups, aromatic heterocyclic groups, acyclic aliphatic hydrocarbon groups having 4 to 39 carbon atoms or 4 carbon atoms via a divalent linking group composed of a group or a combination thereof. ~ 39 cyclic aliphatic hydrocarbon groups may be linked. R ⁵ and R ⁶ each independently represent a hydrogen atom or a substituent, and when there are a plurality of ^{R 5} and R ^{6, they are the same.} It may be different or different.)

5. A method for producing a polyimide resin composition containing polyimide.
Table II of the specification (paragraph [0356]), wherein the solubility at 25 ° C. for dichloromethane (100% by weight) or 1,3-dioxolane (100% by weight) is in the range of 0.01 to 10% by weight. A polyimide prepared from any of the polyisoimides selected from PI1 to PI6, PI8 to PI18 and PI20 to PI39, which are A-2, A-7, A-8, A-11, A-13 and A-. B-2, B-7, B-11, B-12, B-14, which have an acid anhydride having a structure represented by 15, A-16 or A-19 and the following aromatic hydrocarbon ring group. A diamine having a structure represented by B-16, B-18, B-19, B-22, B-23, B-24, B-25 or B-26, and C- having the following aromatic heterocyclic group. 1. A diamine having a structure represented by C-3, C-7, C-8 or C-9, or D-3, D-7, D-8 or D having the following cyclic aliphatic hydrocarbon group. A polyimide made of polyisoimide prepared in combination with a diamine having a structure represented by -10 has a partial structure having a NICS value in the range of -15.0 to -7.0, and has a partial structure. a step of molecular weight is added to any of the additives selected from the following additive 1 additive 10 used as compounds wherein a in the range of 250 to 10,000,
The step of rearranging the polyisoimide to form a polyimide and
A method for producing a polyimide resin composition.

6 . The polyimide is the total amount of the isoimide partial structure represented by the following general formula (A1), the imide partial structure represented by the following general formula (A2), and the amic acid partial structure represented by the following general formula (A3). The method for producing a polyimide resin composition according to Item 5 , wherein the polyimide resin composition has 90 mol% or more with respect to 100 mol%).

(In the general formula (A1) ~ (A3), X 2 and ^{Y 2} each independently represent a substituted or unsubstituted tetravalent aromatic hydrocarbon ring group, aromatic heterocyclic group, the 4-39 carbon atoms Represents an acyclic aliphatic hydrocarbon group or a cyclic aliphatic hydrocarbon group having 4 to 39 carbon atoms, and represents a single bond, an oxygen atom, a sulfur atom, an alkylene group, an amide group, a sulfonyl group, an amino group, a sulfide group, and a carbonyl group. A plurality of aromatic hydrocarbon ring groups, aromatic heterocyclic groups, acyclic aliphatic hydrocarbon groups having 4 to 39 carbon atoms or 4 carbon atoms via a divalent linking group composed of a group or a combination thereof. ~ 39 cyclic aliphatic hydrocarbon groups may be linked. R ⁵ and R ⁶ each independently represent a hydrogen atom or a substituent, and when there are a plurality of ^{R 5} and R ^{6, they are the same.} It may be different or different.)

7 . A transparent substrate containing the polyimide resin composition according to any one of items 1 to 4.

8 . A display film containing the polyimide resin composition according to any one of items 1 to 4.

According to the above means of the present invention, it is possible to provide a polyimide resin composition having excellent mechanical properties and suppressed coloring peculiar to polyimide, and a method for producing the same. Furthermore, a transparent substrate and a display film containing a polyimide resin composition can be provided.

Although the mechanism of expression and mechanism of action of the effects of the present invention have not been clarified, it is inferred as follows.

In order to solve the above problems, the present inventors use a polyisoimide which is soluble like a polyamic acid, so that water generated during the imidization reaction does not exist, and a depressurization step for suppressing a dehydrating agent and foaming is performed. We focused on the fact that organic compounds that impart functions to highly elastic and insoluble polyimide can be added.
As a result of diligent studies on means for controlling the intramolecular and intermolecular interactions of polyimide, π-π interactions, CH-π interactions, and hydrogen-bondable organic compounds were found on polyisoimides having an aromatic moiety in the main chain. A resin composition obtained by adding an organic compound to an originally insoluble polyimide can be obtained by adding and then rearranging to form a polyimide, and by using the resin composition, a film having excellent mechanical properties and the like can be obtained. I found that.

On the other hand, since the high-order structure (partially aggregated structure and orientation structure) of the resin has a great influence on the high mechanical properties and the like, which are the characteristics of polyimide, it is important to control the higher-order structure.

Since the compound A according to the present invention has a partial structure in which the NICS value is in the range of -15.0 to -7.0 and the molecular weight is in the range of 250 to 10,000, it has an aromatic moiety. It strongly interacts with the polyimide having π-π interaction, CH-π interaction, hydrogen bond, etc., and suppresses the mobility of the polyimide. Further, it is presumed that the higher-order structure (partially aggregated structure and oriented structure) that greatly contributes to the physical properties of the polyimide can be controlled by suppressing the motility.
In addition, compound A having a molecular weight in the range of 250 to 10,000 has a large number of units that interact with the polyimide and has a large number of interaction points. Therefore, the compound A acts to pseudo-crosslink the polyimides and has a molecular chain. It is thought that the movement is suppressed more, and it is presumed that the mechanical properties etc. have improved.

Further, the reason for coloring polyimide is the formation of an intramolecular charge transfer complex and an intermolecular charge transfer complex.
As a method of suppressing intramolecular charge transfer, a method of weakening the donor property of the amine part constituting the polyimide and the acceptor property of the anhydride, or a method of introducing a twist of the molecule or a cyclic aliphatic hydrocarbon group from the donor. There is a method of preventing the transfer of charge to the acceptor from the molecular structure.
As a method of suppressing intermolecular charge transfer, charge transfer from the donor to the acceptor is performed by suppressing intermolecular packing by introducing substituents and bending groups that disturb crystallinity and regularity and widening the intermolecular distance. There is a method to make it difficult to wake up in terms of distance.

By the way, when the present inventors focused on the crystal portion of polyimide, the structure in which donors or acceptors were packed was particularly stable and had a high probability of existence, and by forming the morphology, the orbitals between molecules overlapped. It was clarified that the absorption wavelength became longer and the color was worse than the structure packed with the donor and the acceptor.

Therefore, by adding the compound A, which suppresses this packing and can increase the intermolecular distance by interacting with the polyimide, the compound A is inserted between the resins and the orbitals of the resins do not overlap. It is considered that the intermolecular charge transfer can be suppressed and the coloring of polyimide can be suppressed.

Further, in general, when polyimide has a structure exhibiting high mechanical properties, it tends to be hard and brittle or flexible, so that there is a trade-off relationship between elastic modulus and folding resistance. However, by containing the isoimide partial structure in the range of 0.05 to 10 mol% with respect to the total amount of the imide partial structure and the amic acid partial structure, a partially soft structure is formed as a higher-order structure of the resin. It is thought that the remaining stress applied during bending can be relaxed. Therefore, it is presumed that a polyimide resin composition having excellent folding resistance can be obtained while maintaining the high elastic modulus characteristic of polyimide.

Sectional drawing which shows the schematic structure of the transparent conductive film Sectional drawing which shows the schematic structure of the touch panel display device

The polyimide resin composition of the present invention has an aromatic moiety having a solubility in dichloromethane (100% by mass) or 1,3-dioxolane (100% by mass) at 25 ° C. in the range of 0.01 to 10% by mass. It is characterized by containing polyimide and compound A having a partial structure having a NICS value in the range of -15.0 to -7.0 and a molecular weight in the range of 250 to 10,000. .. This feature is a technical feature common to the inventions according to each claim.

In an embodiment of the present invention, compound A is a general formula (1) from the viewpoint of strongly interacting with π-π interaction, CH-π interaction, hydrogen bond and the like, and excellent in mechanical properties and optical properties of the polyimide resin film. ) Or (2) is preferable.

Further, from the viewpoint of improving the mechanical properties of the polyimide resin film by having a large number of units that interact with the polyimide and increasing the number of interaction points, it is preferable that the compound A is a polymer having a repeating unit. ..

Further, in order to obtain a polyimide resin film exhibiting excellent mechanical properties and optical properties, the NICS value of the partial structure of compound A is -14.0 to -14.0 to 4 from the viewpoint of strengthening the aromaticity so as to strongly interact with the polyimide. It is preferably in the range of -10.0.

Further, from the viewpoint of interacting with the compound A and having excellent mechanical and optical properties of the polyimide resin film, it is preferable that the polyimide contains 20 mol% or more of the partial structure represented by the general formula (3).

Further, from the viewpoint of relaxing the stress applied during bending, the isoimide partial structure in which the polyimide is represented by the general formula (A1) is represented by the imide partial structure represented by the general formula (A2) and the general formula (A3). It is preferable to have it in the range of 0.05 to 10 mol% with respect to the total amount (100 mol%) of the amic acid partial structure. When the isoimide partial structure is 0.05 mol% or more, it becomes a hard film, and when it is 10 mol% or less, high mechanical properties can be maintained.

The present invention comprises a step of adding compound A having a partial structure having a NICS value in the range of -15.0 to -7.0 and a molecular weight in the range of 250 to 10,000 to polyimideimide. It is possible to provide a method for producing a polyimide resin composition having a step of rearranging polyisoimide to form a polyimide.

In an embodiment of the present invention, from the viewpoint of the mechanical properties and optical properties of the polyimide resin film, the isoimide partial structure in which the polyisoimide is represented by the general formula (A1) is replaced with the imide partial structure represented by the general formula (A2). It is preferably 90 mol% or more with respect to the total amount (100 mol%) of the amic acid partial structure represented by the general formula (A3).

The present invention can provide a transparent substrate containing a polyimide resin composition.

The present invention can provide a display film containing a polyimide resin composition.

Hereinafter, the present invention, its constituent elements, and modes and modes for carrying out the present invention will be described in detail. In the present application, "~" representing a numerical range is used to mean that the numerical values described before and after the numerical range are included as the lower limit value and the upper limit value.

<< Polyimide resin composition >>
The polyimide resin composition of the present invention has an aromatic moiety having a solubility in dichloromethane (100% by mass) or 1,3-dioxolane (100% by mass) at 25 ° C. in the range of 0.01 to 10% by mass. It is characterized by containing polyimide and compound A having a partial structure having a NICS value in the range of -15.0 to -7.0 and a molecular weight in the range of 250 to 10,000. ..

The polyimide resin composition of the present invention preferably contains polyimide as a main component. The inclusion of polyimide as a main component means that the total amount of polyimide in the film is 50% by mass or more. The content of polyimide in the film is preferably 80% by mass or more. When the total amount of polyimide in the film is 50% by mass or more, it is preferable from the viewpoint of improving folding resistance, heat resistance, and elastic modulus.

Hereinafter, each material will be described in detail.

<Polyimide>
The polyimide according to the present invention has an aromatic moiety having a solubility in dichloromethane (100% by mass) or 1,3-dioxolane (100% by mass) at 25 ° C. in the range of 0.01 to 10% by mass. , A resin containing an imide bond as a repeating unit.
By using such a polyimide, it is possible to improve the handleability in the film manufacturing process such as the solution film forming step and the drying step described later, and the mechanical properties, heat resistance, bending resistance and the like of the film. If the solubility is less than 0.01% by mass, the solubility of the resin is low even when isoimidated and it is difficult to form a solution. If the solubility is larger than 10% by mass, the interaction of polyimide is weak and the effect of compound A can be obtained. do not have.

The polyimide according to the present invention is preferably a resin having an imide partial structure represented by the following general formula (A2).

In the general formula (A2), X ² and Y ² are independently substituted or unsubstituted tetravalent aromatic hydrocarbon ring groups, aromatic heterocyclic groups, and acyclic aliphatic groups having 4 to 39 carbon atoms. Represents a hydrocarbon group or a cyclic aliphatic hydrocarbon group having 4 to 39 carbon atoms, and contains a single bond, an oxygen atom, a sulfur atom, an alkylene group, an amide group, a sulfonyl group, an amino group, a sulfide group, a carbonyl group, or these. Multiple aromatic hydrocarbon ring groups, aromatic heterocyclic groups, acyclic aliphatic hydrocarbon groups having 4 to 39 carbon atoms or cyclic groups having 4 to 39 carbon atoms via a combination of divalent linking groups. An aliphatic hydrocarbon group may be linked.

Examples of the aromatic hydrocarbon ring group represented by X ² and Y ² include a benzene ring, a biphenyl ring, a naphthalene ring, a fluorene ring, an anthracene ring, a phenanthrene ring, a pyrene ring, a chrysene ring, a naphthacene ring, and a triphenylene ring. o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorantrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphene ring, picene ring, pyrene ring, pyrentrene ring, Examples thereof include groups derived from anthrananthrene rings and the like.
Of these, a benzene ring, a biphenyl ring, a naphthalene ring, and a pyrene ring are preferable, and a benzene ring, a biphenyl ring, and a naphthalene ring are more preferable. Mechanical properties can be improved by introducing these groups.

Examples of the aromatic heterocyclic group represented by X ² and Y ² include a silol ring, a furan ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, and an oxa. Diazol ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzthiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, thienothiophene ring, carbazole ring, azacarbazole ring. (Represents any one or more of the carbon atoms constituting the carbazole ring replaced with a nitrogen atom.), Dibenzosilol ring, dibenzofuran ring, dibenzothiophene ring, benzothiophene ring or any carbon atom constituting the dibenzofuran ring. A ring in which one or more of the rings are replaced with a nitrogen atom, a benzodifuran ring, a benzodithiophene ring, an aclysine ring, a benzoquinoline ring, a phenazine ring, a phenanthridine ring, a phenanthroline ring, a cyclazine ring, a kindrin ring, a tepenidine ring, a quinindrin ring, Triphenodithiazine ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, naphthofuran ring, naphthothiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, anthrathiophene ring, Examples thereof include groups derived from anthradithiophene ring, thianthene ring, phenoxatiin ring, dibenzocarbazole ring, indolocarbazole ring, dithienobenzene ring and the like.
Of these, a pyridine ring, a pyrimidine ring, a triazine ring, a benzimidazole ring, and a quinazoline ring are preferable, and a pyridine ring, a pyrimidine ring, and a triazine ring are more preferable. By introducing these groups, mechanical properties and transparency can be improved.

Examples of the acyclic aliphatic hydrocarbon group having 4 to 39 carbon atoms represented by X ² and Y ^{2 include butane-1,1,4,4-tetrayl group and octane-1,1,8,8.} -Tetrayl group, decane-1,1,10,10-tetrayl group and the like can be mentioned.

Examples of the cyclic aliphatic hydrocarbon group having 4 to 39 carbon atoms represented by X ² and Y ^{2 include cyclobutane-1,2,3,4-tetrayl group and cyclopentane-1,2,4,5.} -Tetrayl group, cyclohexane-1,2,4,5-tetrayl group, bicyclo [2.2.2] octo-7-en-2,3,5,6-tetrayl group, bicyclo [2.2.2] Octane-2,3,5,6-tetrayl group, 3,3', 4,4'-dicyclohexyltetrayl group, 3,6-dimethylcyclohexane-1,2,4,5-tetrayl group, 3,6- Examples thereof include a diphenylcyclohexane-1,2,4,5-tetrayl group.
Among them, cyclobutane-1,2,3,4-tetrayl group, cyclopentane-1,2,4,5-tetrayl group, cyclohexane-1,2,4,5-tetrayl group, bicyclo [2.2.2]. Oct-7-ene-2,3,5,6-tetrayl groups are preferred, cyclobutane-1,2,3,4-tetrayl groups, cyclopentane-1,2,4,5-tetrayl groups, cyclohexane-1, 2,4,5-Tetrayl groups are more preferred. By introducing these groups, transparency and mechanical properties can be improved.

Multiple X ² and Y ² are linked via a single bond, an oxygen atom, a sulfur atom, an alkylene group, an amide group, a sulfonyl group, an amino group, a sulfide group, a carbonyl group, or a divalent linking group consisting of a combination thereof. If so, the X ² and Y ² have a predetermined valence, such as the aromatic hydrocarbon ring group, the aromatic heterocyclic group, the acyclic aliphatic hydrocarbon group having 4 to 39 carbon atoms, or 4 carbon atoms. Examples thereof include those similar to the cyclic aliphatic hydrocarbon groups of ~ 39.

The ^{substituents that X 2} and Y ² may have are not particularly limited as long as the effects of the present invention are not impaired, but for example, hydrogen atom and halogen atom (fluorine atom, chlorine atom, bromine). Atomic, iodine atom, etc.), alkyl group (methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group, 2-ethylhexyl group, etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group, etc.) , 4-n-dodecylcyclohexyl group, etc.), alkenyl group (vinyl group, allyl group, etc.), cycloalkenyl group (2-cyclopenten-1-yl, 2-cyclohexene-1-yl group, etc.), alkynyl group (ethynyl group, etc.) , Propargyl group, etc.), aryl group (phenyl group, p-tolyl group, naphthyl group, etc.), heteroaryl group (2-pyrrole group, 2-furyl group, 2-thienyl group, pyrrole group, imidazolyl group, oxazolyl group, etc. Thiazolyl group, benzoimidazolyl group, benzoxazolyl group, 2-benzothiazolyl group, pyrazolinone group, pyridyl group, pyridinone group, 2-pyrimidinyl group, etc.), cyano group, hydroxy group, nitro group, carboxy group, alkoxy group (methoxy group) , Ethoxy group, isopropoxy group, tert-butoxy group, n-octyloxy group, 2-methoxyethoxy group, etc.), aryloxy group (phenoxy group, 2-methylphenoxy group, 4-tert-butylphenoxy group, 3- Nitrophenoxy group, 2-tetradecanoylaminophenoxy group, etc.), acyl group (acetyl group, pivaloylbenzoyl group, etc.), acyloxy group (formyloxy group, acetyloxy group, pivaloyloxy group, stearoyloxy group, benzoyloxy group, etc.) , P-methoxyphenylcarbonyloxy group, etc.), Amino group (amino group, methylamino group, dimethylamino group, anilino group, N-methyl-anilino group, diphenylamino group, etc.), acylamino group (formylamino group, acetylamino group, etc.) Group, pivaloylamino group, lauroylamino group, benzoylamino group, etc.), alkyl and arylsulfonylamino groups (methylsulfonylamino group, butylsulfonylamino group, phenylsulfonylamino group, 2,3,5-trichlorophenylsulfonylamino group, p. -Methylphenylsulfonylamino group, etc.), mercapto group, alkylthio group (methylthio group, ethylthio group, n-hexadecylthio group, etc.), arylthio group (phenylthio group, p- Chlorophenylthio group, m-methoxyphenylthio group, etc.), sulfamoyl group (N-ethylsulfamoyl group, N- (3-dodecyloxypropyl) sulfamoyl group, N, N-dimethylsulfamoyl group, N-acetylsul Famoyl group, N-benzoyl sulfamoyl group, N- (N'-phenylcarbamoyl) sulfamoyl group, etc.), sulfo group, carbamoyl group (carbamoyl group, N-methylcarbamoyl group, N, N-dimethylcarbamoyl group, N , N-di-n-octylcarbamoyl group, N- (methylsulfonyl) carbamoyl group, etc.) and the like. These groups may be further substituted with similar groups.

Further, the polyimide according to the present invention is synthesized from a polyamic acid via polyisoimide as described later, and the isoimide partial structure represented by the following general formula (A1) is represented by the above general formula (A2). It is preferably contained in the range of 0.05 to 10 mol% with respect to the total amount (100 mol%) of the imide partial structure represented and the amic acid partial structure represented by the following general formula (A3).
Here, the content of the isoimide partial structure represented by the general formula (A1) in the polyimide is determined by nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), and ultraviolet-visible absorption spectroscopy (UV-vis). Etc. can be measured. For example, it is measured by the area of the peak of NMR or by a Fourier transform infrared spectrometer.

In formula (A1) and (A3), ^{X 2} and ^{Y 2} has the same meaning as ^{X 2} and ^{Y 2} in formula (A2).
In the general formula (A3), R ⁵ and R ⁶ each independently represent a hydrogen atom or a substituent, ^{and when there are a plurality of R 5} and R ⁶ , they may be the same or different. ..

Examples of the substituent represented by R ⁵ and R ^{6 include the same substituents that X 2} and Y ² in the general formula (A2) may have.

Further, the polyimide according to the present invention preferably has a partial structure represented by the following general formula (3) in an amount of 20 mol% or more.
Here, the content of the partial structure represented by the general formula (3) in the polyimide includes nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), ultraviolet-visible absorption spectroscopy (UV-vis), and the like. Can be measured with. For example, it is measured by the area of the peak of NMR or by a Fourier transform infrared spectrometer.

In the general formula (3), X ¹ is a single bond, an oxygen atom, a sulfur atom, an alkylene group, an amide group, a sulfonyl group, an amino group, a sulfide group, a carbonyl group, or a divalent linking group consisting of a combination thereof. show. R ³ and R ⁴ independently represent a hydrogen atom or a substituent, ^{and when there are a plurality of R 3} and R ⁴ , they may be the same or different. p and q represent an integer of 0 to 4, and r represents an integer of 0 to 3. However, when X ¹ is a single bond, p or q represents an integer of 1 or more, and when r = 0, p represents an integer of 1 or more.

Examples of the substituent represented by R ³ and R ^{4 include the same substituents that X 2} and Y ² in the general formula (A2) may have.

(Polyimide synthesis method)
The polyimide according to the present invention is synthesized from polyamic acid via polyisoimide.
Hereinafter, each step will be described.

(1) Synthesis of Polyamic Acid Polyamic acid can be synthesized by a known general method, and is obtained by reacting a diamine with an acid anhydride, for example, a tetracarboxylic dianhydride in an organic solvent. be able to. More specifically, for example, in an atmosphere of an inert gas such as argon or nitrogen, diamine is dissolved in an organic solvent or dispersed in a slurry to prepare a diamine solution. On the other hand, it can be synthesized by dissolving tetracarboxylic dianhydride in an organic solvent or dispersing it in a slurry, or by adding it to a diamine solution in a solid state. Of course, the method for reacting the diamine with the tetracarboxylic dianhydride is not limited to this, and the method and order of addition can be appropriately selected.

The polyamic acid ester is formed by diesterifying tetracarboxylic acid dianhydride with an alcohol such as methanol, ethanol, isopropanol, or n-propanol, and reacting the obtained diester with a diamine in a suitable solvent. Can be obtained by Further, the polyamic acid ester can also be obtained by esterifying the carboxylic acid group of the polyamic acid obtained as described above by reacting with the alcohol as described above.

The amount of diamine is usually in the range of 0.8 to 1.2 mol, preferably in the range of 1 to 1.1 mol with respect to 1 mol of tetracarboxylic dianhydride. By setting the amount of diamine within such a range, the yield of the obtained polyamic acid can be improved. Further, by adjusting the number of moles of the total amount of the single or plural diamine components and the number of moles of the total amount of the single or multiple tetracarboxylic dianhydride components to substantially the same mole, the polyamic acid copolymer can be arbitrarily prepared. Obtainable.

The concentrations of tetracarboxylic dianhydride and diamine in the solvent are appropriately set according to the reaction conditions and the viscosity of the polyamic acid solution. For example, the total mass of the tetracarboxylic dianhydride and the diamine compound is not particularly limited, but is usually in the range of 1 to 70% by mass, preferably in the range of 5 to 30% by mass, based on the total amount of the solution. Is inside. By setting the amount of the reaction substrate within such a range, polyamic acid can be obtained at low cost and in good yield.

The reaction temperature is not particularly limited, but is usually in the range of 0 to 100 ° C, preferably in the range of 20 to 80 ° C.
The reaction time is not particularly limited, but is usually 1 to 100 hours, preferably 2 to 24 hours. By carrying out the reaction under such conditions, polyamic acid can be obtained at low cost and in good yield.

Examples of the polymerization solvent used in this reaction include hydrocarbon solvents such as hexane, cyclohexane, heptane, benzene, toluene, xylene and mesitylen, carbon tetrachloride, dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene and dichlorobenzene. , Halogened hydrocarbon solvent such as fluorobenzene, ether solvent such as diethyl ether, tetrahydrofuran, 1,4-dioxane, methoxybenzene, ketone solvent such as acetone and methyl ethyl ketone, N, N-dimethylformamide, N, N- Amido solvents such as dimethylacetamide and N-methyl-2-pyrrolidone, aproton polar solvents such as dimethylsulfoxide and γ-butyrolactone, heterocyclic solvents such as pyridine, picolin, lutidine, quinoline and isoquinolin, phenols, cresols and the like. Examples thereof include, but are not particularly limited to. As the polymerization solvent, only one kind may be used, or two or more kinds of solvents may be mixed and used.

As the terminal group of the polyamic acid, an acid anhydride group and an amino group can be arbitrarily selected by excessively using either one of the tetracarboxylic dianhydride and the diamine at the time of the polymerization reaction.

When the terminal group is an acid anhydride terminal, the acid anhydride terminal may be left as it is without further treatment, or it may be hydrolyzed to obtain a dicarboxylic acid. Further, an alcohol having 4 or less carbon atoms may be used as an ester.
In addition, monofunctional amines or isocyanates may be used to seal the ends. The amine or isocyanate used here is not particularly limited as long as it is a monofunctional primary amine or isocyanate. For example, aniline, methylaniline, dimethylaniline, trimethylaniline, ethylaniline, diethylaniline, triethylaniline, aminophenol, methoxyaniline, aminobenzoic acid, biphenylamine, naphthylamine, cyclohexylamine, phenylisocyanate, xylylene isocyanate, cyclohexylisocyanate. , Methylphenyl isocyanate, trifluoromethylphenyl isocyanate and the like.

When the terminal group is an amine terminal, the amino group can be prevented from remaining at the terminal by sealing the terminal amino group with a monofunctional acid anhydride. The acid anhydride used here is not particularly limited as long as it is a monofunctional acid anhydride that becomes a dicarboxylic acid or a tricarboxylic acid when hydrolyzed. For example, maleic anhydride, methylmaleic anhydride, dimethylmaleic anhydride, succinic anhydride, norbornendicarboxylic acid anhydride, 4- (phenylethynyl) phthalic anhydride, 4-ethynylphthalic anhydride, phthalate. Acid anhydride, methylphthalic anhydride, dimethylphthalic anhydride, trimellitic anhydride, naphthalenedicarboxylic acid anhydride, 7-oxabicyclo [2.2.1] heptane-2,3-dicarboxylic acid anhydride, bicyclo [2.2.1] Heptane-2,3-dicarboxylic acid anhydride, bicyclo [2.2.2] Octa-5-ene-2,3-dicarboxylic acid anhydride, 4-oxatricyclo [5.2] .2.02,6] Undecane-3,5-dione, octahydro-1,3-dioxoisobenzofuran-5-carboxylic acid, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, dimethylcyclohexanedicarboxylic acid Anhydrides, 1,2,3,6-tetrahydrophthalic anhydrides, methyl-4-cyclohexene-1,2-dicarboxylic acid anhydrides and the like can be mentioned.

(1.1) Acid Anhydride The acid anhydride is not particularly limited, and examples thereof include tetracarboxylic dianhydride having a structure represented by the following general formula (A).

In the general formula (A), R is a substituted or unsubstituted tetravalent aromatic hydrocarbon ring group, an aromatic heterocyclic group, an acyclic aliphatic hydrocarbon group having 4 to 39 carbon atoms or 4 to 4 carbon atoms. Representing 39 aliphatic hydrocarbon groups, via a single bond, an oxygen atom, a sulfur atom, an alkylene group, an amide group, a sulfonyl group, an amino group, a sulfide group, a carbonyl group, or a divalent linking group consisting of a combination thereof. A plurality of aromatic hydrocarbon ring groups, aromatic heterocyclic groups, acyclic aliphatic hydrocarbon groups having 4 to 39 carbon atoms or cyclic aliphatic hydrocarbon groups having 4 to 39 carbon atoms are linked. May be good. When there are a plurality of substituents, they may be the same or different.

R in the general formula (A) is synonymous with ^{X 2} and Y ^{2 in the general formula (A2).}

The tetracarboxylic dianhydride having a structure represented by the general formula (A) is an acid anhydride having a structure represented by the following A-1 to A-19 in terms of mechanical properties, transparency, cost and the like. Is preferable.

(1.2) Diamine The diamine is not particularly limited, and examples thereof include diamines having a structure represented by the following general formula (B).

In the general formula (B), R is a substituted or unsubstituted divalent aromatic hydrocarbon ring group, an aromatic heterocyclic group, an acyclic aliphatic hydrocarbon group having 2 to 39 carbon atoms, or a non-cyclic aliphatic hydrocarbon group having 2 to 39 carbon atoms. Representing 39 cyclic aliphatic hydrocarbon groups, a single bond, an oxygen atom, a sulfur atom, an alkylene group, an amide group, a sulfonyl group, an amino group, a sulfide group, a carbonyl group, or a divalent linking group consisting of a combination thereof. A plurality of aromatic hydrocarbon ring groups, aromatic heterocyclic groups, acyclic aliphatic hydrocarbon groups having 2 to 39 carbon atoms or cyclic aliphatic hydrocarbon groups having 2 to 39 carbon atoms are linked via the above. You may be. When there are a plurality of substituents, they may be the same or different.

Examples of the aromatic hydrocarbon ring group represented by R include a benzene ring, a biphenyl ring, a naphthalene ring, an azulene ring, a fluorene ring, an anthracene ring, a phenanthrene ring, a pyrene ring, a chrysen ring, a naphthacene ring, a triphenylene ring, and an otel. Pyrene ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronen ring, fluorantene ring, naphthalene ring, pentacene ring, perylene ring, pentaphene ring, picene ring, pyrene ring, pyranthrene ring, anthranetrene A group derived from a ring or the like, or these are linked via a single bond, an oxygen atom, a sulfur atom, an alkylene group, an amide group, a sulfonyl group, an amino group, a sulfide group, a carbonyl group, or a group consisting of a combination thereof. The group and the like can be mentioned.
The diamine is preferably a diamine having a structure represented by B-1 to B-27 having the following aromatic hydrocarbon ring groups from the viewpoint of mechanical properties and heat resistance.

Examples of the aromatic heterocyclic group represented by R include a silol ring, a furan ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, and an oxaziazole ring. Triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzthiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, thienothiophene ring, carbazole ring, azacarbazole ring (carbazole ring) Any one or more of the constituent carbon atoms are replaced with nitrogen atoms.), Any one or more of the carbon atoms constituting the dibenzosilol ring, dibenzofuran ring, dibenzothiophene ring, benzothiophene ring or dibenzofuran ring. Ring replaced with a nitrogen atom, benzodifuran ring, benzodithiophene ring, aclysine ring, benzoquinoline ring, phenazine ring, phenanthridine ring, phenanthroline ring, cyclazine ring, kindrin ring, tepenidine ring, quinindrin ring, triphenodithiazine Ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, naphthofuran ring, naphthothiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, anthrathiophene ring, anthradithiophene ring , Thiophene ring, phenoxatiin ring, dibenzocarbazole ring, indolocarbazole ring, dithienobenzene ring, etc., or an aromatic heterocyclic group represented by R is an ether bond, an alkylene group, or a simple bond. Examples thereof include a group connected in multiples with.
Of these, a pyridine ring, a pyrimidine ring, a triazine ring, a benzimidazole ring, and a quinazoline ring are preferable, and a pyridine ring, a pyrimidine ring, and a triazine ring are more preferable. By introducing these groups, mechanical properties, heat resistance, and transparency can be improved.

The diamine is preferably a diamine having a structure represented by C-1 to C-9 having the following aromatic heterocyclic group.

Examples of the divalent acyclic aliphatic hydrocarbon group having 2 to 39 carbon atoms represented by R include, for example, a linear or branched acyclic aliphatic hydrocarbon group having 2 to 39 carbon atoms. Examples thereof include groups represented by the following structural formulas.

In the above structural formula, n represents the number of repeating units, preferably 1 to 5, and more preferably 1 to 3. X represents an alkanediyl group having 1 to 3 carbon atoms, that is, a methylene group, an ethylene group, a trimethylene group, and a propane-1,2-diyl group, and a methylene group is particularly preferable.

The diamine is preferably a diamine having a structure represented by D-1 to D-11 having the following cyclic aliphatic hydrocarbon group.

Examples of the substituent that R may have include the same substituents that X ² and Y ² in the general formula (A2) may have.

(2) Isoimided In the isoimidation method, polyisoimide is obtained by ring-closing the above polyamic acid or polyamic acid ester with an isoimidating agent and isoimidizing the polyisoimide.

The isoimide agent is not particularly limited, and examples thereof include a dehydration condensing agent.
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, and chlorides such as thionyl chloride and tosyl chloride. Things, acetyl chloride, acetyl bromide, propionyl chloride, acetyl fluoride, propionyl chloride, propionyl bromide, propionyl chloride, propionyl fluoride, isobutyryl chloride, isobutyryl bromide, isobutyryl iodide, isobutyryl fluoride Ride, 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, thionyl iodide, thionyl fluoride, etc. Examples thereof include halogenated compounds of the above, phosphorus trichlorides, triphenyl phosphite, and phosphorus compounds such as diethyl phosphate cyanide.
These isoimidating agents are appropriately selected depending on the type of polycarboxylic acid dianhydride and diamine constituting the polyamic acid or polyamic acid ester. These can be used alone or in combination of two or more.

The amount of these dehydration condensing agents used is usually in the range of 0.5 to 20 mol, preferably in the range of 1 to 10 mol, with respect to 1 mol of the polyamic acid or polyamic acid ester skeleton.

Further, a ring closure catalyst may be used in combination with the dehydration condensing agent. It is preferable to use the dehydration condensing agent and the ring closure catalyst in combination because the isoimidization reaction proceeds efficiently.
Examples of the ring-closing catalyst include organic amine compounds such as trimethylamine, triethylamine, tri-n-butylamine, N, N-dimethylethanolamine, N, N-dimethyldodecylamine and triethylenediamine, pyridine, picoline, 2,6-lutidine, 2 , 4,6-Colidine, quinoline, pyrazine, 2-methylpyrazine and other heterocyclic compounds.
The amount of the ring-closing catalyst used is usually in the range of 0.001 to 10 mol, preferably in the range of 0.01 to 4 mol, with respect to 1 mol of the polyamic acid or polyamic acid ester skeleton.

The dehydration condensing agent is particularly preferably acetic anhydride. It has little toxicity and by-products and can be preferably used.
Further, in order to facilitate the dehydration ring closure reaction, it is preferable to use a ring closure catalyst such as pyridine in combination.

The isomidization reaction by ring closure is carried out by reacting a polyamic acid or a polyamic acid ester with an isoimidating agent, but the reaction method may be any conventionally known method, for example, addition of an isoimidating agent or an isoimidating agent. There is a method of immersing in. At that time, the isoimider may be used as it is or as a solution diluted with an organic solvent.

Examples of the organic solvent include hydrocarbon solvents such as hexane, cyclohexane, heptane, benzene, toluene and xylene, carbon tetrachloride, methylene chloride, chloroform, dichloromethane, 1,2-dichloroethane, chlorobenzene, dichlorobenzene, fluorobenzene and the like. Halogenized hydrocarbon solvent, ether solvent such as diethyl ether, tetrahydrofuran, 1,4-dioxane, methoxybenzene, diethylene glycol solvent such as diethoxyethylene glycol, dimethoxyethylene glycol, diethoxydiethylene glycol, dimethoxydiethylene glycol, acetone, methyl ethyl ketone Etc., ketone solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone and the like, aproton solvents such as dimethylsulfoxide and γ-butyrolactone, phenol, Examples thereof include phenolic solvents such as cresole and dichloromethane.
These solvents can be used alone or in combination of two or more.
The amount of the solvent used is not particularly limited, but from the viewpoint of work, the concentration of the polyisoimide produced is usually adjusted to be in the range of 5 to 80% by mass, preferably in the range of 10 to 50% by mass. ..

The reaction temperature for isoimidization is not particularly limited, but is usually in the range of -30 to 100 ° C, preferably in the range of -20 to 60.
The reaction time for isoimidization is not particularly limited, but is usually 15 minutes to 50 hours, preferably 30 minutes to 24 hours.

The desired polyisoimide can be obtained by removing the solvent from the solution containing the polyisoimide thus obtained at 0 to 80 ° C. under normal pressure or reduced pressure.

The desired polyisoimide can also be obtained by a reprecipitation operation in which a solution containing polyisoimide is poured into a poor solvent.
Examples of the poor solvent include ethers such as diethyl ether and diisopropyl ether, ketones such as acetone, methyl ethyl ketone, isobutyl ketone and methyl isobutyl ketone, and alcohols such as methanol, ethanol and isopropyl alcohol.

At that time, if necessary, filtration, centrifugation or washing may be carried out to remove by-products before reprecipitation. In addition, the polyisoimide solution can also be used in the state of the solution in the manufacturing process of the polyimide molded product, which is a subsequent step.

The polyisoimide is a total amount (100 mol) of the isoimide partial structure represented by the general formula (A1), the imide partial structure represented by the general formula (A2), and the amic acid partial structure represented by the general formula (A3). %), It is preferable to have 90 mol% or more.

The progress of isoimide formation (content of isoimide partial structure) can be measured by nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), ultraviolet-visible absorption spectroscopy (UV-vis), or the like. For example, it is measured by the area of the peak of NMR or by a Fourier transform infrared spectrometer.
Specifically, isoimide backbone derived peak area _{(= S iso)} and the area of a peak derived from the imide skeleton _{(= S im),} be expressed by the area ratio of the peak area derived from the amide backbone _{(= S paa)} can, isoimidization rate (isoimide skeleton content) is _{(= S iso / (S paa} + S iso + S im).

(3) Imidization The polyimide can be obtained by imidizing the polyisoimide synthesized as described above.

The polyisoimide can be rearranged to polyimide without dehydration, for example, by heating. Therefore, it is preferable because the shrinkage of the molded product when dislocating from polyisoimide to polyimide can be suppressed, and since water is not generated and its volatilization does not occur, deterioration of physical properties and defects of the molded product can be prevented.

The heating temperature is not particularly limited as long as it is higher than the dislocation temperature, but is usually 100 ° C. or higher, more preferably 150 ° C. or higher, while it is usually 350 ° C. or lower, preferably 300 ° C. or lower, more preferably 250 ° C. or higher. It is below ° C.
The reaction time at this time is not particularly limited, but is usually 30 minutes to 3 hours, preferably 1 to 2 hours.

Examples of the heating method include hot air heating, vacuum heating, infrared heating, microwave heating, and heating by contact using a hot plate or a hot roll. In this case, it is preferable to proceed with imidization by raising the temperature stepwise. The environment at this time may be under air, an inert atmosphere, or a vacuum, but it is preferably performed under an inert atmosphere.

The progress of imidization (content of the imide partial structure) can be measured by nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), ultraviolet-visible absorption spectroscopy (UV-vis), or the like. For example, it is measured by the area of the peak of NMR or by a Fourier transform infrared spectrometer.
Specifically, isoimide backbone derived peak area _{(= S iso)} and the area of a peak derived from the imide skeleton _{(= S im),} be expressed by the area ratio of the peak area derived from the amide backbone _{(= S paa)} can, imidization ratio (imide skeleton content) is _{(= S im / (S iso} + S paa + S im).

The upper limit of the imidization rate is 100%, usually in the range of 80% to 100%, preferably in the range of 90 to 99.5%. From the viewpoint of relaxing the stress applied during bending, the polyimide has an isoimide partial structure represented by the general formula (A1), an imide partial structure represented by the general formula (A2), and an amide acid represented by the general formula (A3). It is preferable to have it in the range of 0.05 to 10 mol% with respect to the total amount (100 mol%) of the partial structure. When the isoimide partial structure is 0.05 mol% or more, it becomes a hard film, and when it is 10 mol% or less, high mechanical properties can be maintained.

(Weight average molecular weight)
The weight average molecular weight of the polyimide according to the present invention is not particularly limited, but is preferably in the range of 1000 to 1,000,000, and more preferably in the range of 2000 to 500000.

In the present invention, the weight average molecular weight is measured by gel permeation chromatography (GPC). An example of the measurement conditions is shown below, but the present invention is not limited to this, and an equivalent measurement method can be used.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Use by connecting 3 pieces manufactured by Showa Denko KK)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Science)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 500 to 1000000 A calibration curve with 13 samples is used. 13 samples are used at approximately equal intervals.

<Compound A>
The compound A according to the present invention is characterized by having a partial structure having a NICS value in the range of -15.0 to −7.0 and a molecular weight in the range of 250 to 10,000.

Compound A, which has a large number of interaction units and has a molecular weight in the range of 250 to 10,000, has a large number of interaction points, so that it acts to pseudo-crosslink the polyimides and further suppresses the molecular chain motion of the polyimides. be able to. When the molecular weight of compound A is less than 250, the number of interaction points is small and the molecular motion of polyimide cannot be suppressed, and when the molecular weight exceeds 10,000, compound A aggregates due to the difference in compatibility between compound A and polyimide. However, it causes a decrease in haze and a decrease in mechanical properties.

Further, when the NICS value is in the range of -15.0 to -7.0, the physical properties are improved by the interaction force such as π-π interaction, CH-π interaction, and hydrogen bond with the polyimide having an aromatic moiety. It can be improved. When the NICS value of compound A is less than -15.0, the interaction force is strong, and the crystallization of compound A proceeds due to its own intermolecular force, and when the NICS value exceeds -7.0, the mutual force is mutual. The force of action is weak, and it is not possible to interact appropriately with polyimide.

Further, as the compound A, a compound having a donor property and an acceptor property is preferable. By using the compound A having a donor property and an acceptor property, it is possible to exhibit not only the above-mentioned effect of suppressing intermolecular charge transfer due to the widening of the intermolecular distance, but also the effect of suppressing intramolecular charge transfer. This is because compound A, which has donor and acceptor properties, interacts with polyimide to weaken the donor and acceptor properties derived from the polyimide structure by the donor and acceptor properties of compound A, so that it is intramolecular. It is presumed that the effect of suppressing charge transfer is also exhibited, and the coloring peculiar to polyimide is suppressed.

(NICS value)
For example, when a π / π interaction is formed between a polyimide having an aromatic moiety and π electrons of compound A, it is naturally preferable that the π property of compound A is strong. As an example of simply expressing the strength of this π property, there is an index called a NICS (nucleus-independent chemical shift) value.

This NICS value is an index used for quantifying aromaticity due to magnetic properties. If the ring is aromatic, the center of the ring is strongly shielded by the ring current effect, and conversely if it is antiaromatic. It is anti-shielded (J. Am. Chem. Soc. 1996, 118, 6317). From the magnitude of the NICS value, the strength of the ring current, that is, the contribution of π electrons to the aromaticity of the ring can be determined. Specifically, it represents the chemical shift (calculated value) of virtual lithium ions placed directly in the center of the ring, and the larger this value is, the stronger the π property.

Several reports have been made on the measured NICS values. For example, the Journal of Chemistry. , 2004, 82, 50-69 and The Journal of Organic Chemistry. , 2000, 67, 1333-1338, etc., the measured values are reported.

In the present invention, the NICS value is calculated using Gaussian09 (Revision C.01, software manufactured by Gaussian, Inc., USA). Specifically, first, the structure is optimized using B3LYP (density functional theory) as the calculation method and 6-31G ^* (a function obtained by adding a polarization function to the split variance basis set) as the basis function. Then, using the optimized structure, a dummy atom is placed in the center of the ring for calculating the NICS value, and one point is calculated by the NMR shielding constant calculation method (GIAO) with ^{the basis function 6-311G ** to which the dispersion function is added.} , The value obtained by multiplying the NMR shielding constant of the obtained dummy atom by -1 is taken as the NICS value.

Table 1 shows the NICS values in the typical ring structures described in the literature.

As shown in Table 1, the NICS value of a 5-membered aromatic heterocycle such as a pyrrole ring, a thiophene ring, or a furan ring is larger than that of an aromatic hydrocarbon ring such as a benzene ring or a naphthalene ring. It is expected that the π / π interaction can be strengthened by using such an aromatic 5-membered ring.

The π / π interaction is an intermolecular force acting between two aromatic rings, and since the aromatic ring has a large polarizability, it is an intermolecular force in which the dispersion force (London dispersion force) contributes greatly. Therefore, the broad aromatic ring of the π-conjugated system has a larger polarizability and facilitates π / π interaction. Benzene, which is a 6π-electron system, has the most stable structure when another benzene ring is arranged vertically on one benzene ring and the benzene ring and hydrogen atom interact with CH / π, whereas π-conjugated benzene. Benzene (10π electrons) and anthracene (14π electrons), which have a wide system, are most stable when aromatic rings are stacked by π / π interaction. It turns out that is strong.

Furthermore, as a result of the studies conducted by the present inventors, if the interaction such as charge transfer interaction and hydrogen bond is utilized in addition to the π / π interaction force, the resin can be strongly coordinated. I thought. That is, by using a compound having a donor property / acceptor property capable of charge transfer interaction or a compound having a hydrogen bond site in addition to the aromatic property, the compound A is in a state of being inserted between the packed polyimides. It is considered that the aggregated structure and the oriented structure are effective in suppressing the coloration peculiar to polyimide in addition to improving the physical properties such as high mechanical properties.

(Compound having a structure represented by the general formula (1))
The compound A according to the present invention is preferably a compound having a structure represented by the following general formula (A).

In the general formula (1), ring A represents a 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocycle. R ¹ represents a hydrogen atom or a substituent, when R ¹ are a plurality, may be R ¹ is identical to each other or may be different. L is a single bond, oxygen atom, sulfur atom, amide group, sulfonyl group, amino group, sulfide group, carbonyl group, phosphate ester group, acyclic aliphatic hydrocarbon group, cyclic aliphatic hydrocarbon group, fat. It represents a group heterocyclic group, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, or a divalent linking group composed of a combination thereof. Ring B represents a 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocycle. R ² represents a hydrogen atom or a substituent. If L- ring ^{B-R 2} there are a plurality, L- ring ^{B-R 2} may be the same or may be different from one another. l represents an integer of 0 to 5, m represents an integer of 1 to 5, and n represents an integer of 1 to 6.

Examples of the 5- or 6-membered aromatic heterocycle represented by rings A and B include an oxazole ring, an oxadiazole ring, an oxatriazole ring, an isoxazole ring, a tetrazole ring, a thiathiazole ring, a thiatriazole ring, and an isothiazole ring. Examples thereof include a ring, a thiophene ring, a furan ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an imidazole ring, a pyrazole ring, and a triazole ring.

Examples of the acyclic aliphatic hydrocarbon group represented by L include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, an isobutylene group, an s-butylene group and a t-butylene group. , Pentylene group, hexylene group, heptylene group, alkylene group such as octylene group and the like. A part thereof may be saturated or unsaturated, may be linear or branched, and may contain a hetero atom such as an oxygen atom.
Examples of the cyclic aliphatic hydrocarbon group represented by L include a cycloalkylene group such as a cyclopropylene group, a cyclobutylene group, a cyclopentylene group and a cyclohexylene group. A part thereof may be saturated or unsaturated, may have a substituent, and may contain a hetero atom such as an oxygen atom.
Examples of the aliphatic heterocyclic group represented by L include a divalent group derived from a 2-oxopyrrolidine ring, a piperidine ring, a piperazine ring, a morpholine ring, a tetrahydrofuran ring, a tetrahydropyran ring, a tetrahydrotythiophene ring and the like. Be done.

Examples of the substituent represented by R ¹ and R ^{2 include the same substituents that X 2} and Y ² in the general formula (A2) may have.

(Compound having a structure represented by the general formula (2))
The compound having the structure represented by the general formula (1) is more preferably a compound having the structure represented by the following general formula (2).

In the general formula (2), A ^{1 to} A ⁶ independently represent a carbon atom or a nitrogen atom, but at least two of ^{A 1 to} A ^{6 are carbon atoms.} R ¹ represents a hydrogen atom or a substituent, when R ¹ are a plurality, may be R ¹ is identical to each other or may be different. L is a single bond, oxygen atom, sulfur atom, amide group, sulfonyl group, amino group, sulfide group, carbonyl group, phosphate ester group, acyclic aliphatic hydrocarbon group, cyclic aliphatic hydrocarbon group, fat. It represents a group heterocyclic group, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, or a divalent linking group composed of a combination thereof. Ring B represents a 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocycle. R ² represents a hydrogen atom or a substituent. If L- ring ^{B-R 2} there are a plurality, L- ring ^{B-R 2} may be the same or may be different from one another. l represents an integer of 0 to 5, m represents an integer of 1 to 5, and n represents an integer of 1 to 6.

Examples of the ring formed by A ^{1 to A 6} include a benzene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazine ring, a tetrazine ring and the like.

B in the general formula (2), L, ^{R 1} and ^{R 2} are the B in the general formula (1), L, ^{R 1} and ^{R 2} synonymous.

Specific exemplary compounds 1 to 92 of Compound A according to the present invention are shown below, but the present invention is not limited thereto. In addition, compound A may be a tautomer and may form a hydrate, a solvate or a salt.

(Sugar ester)
Further, a sugar ester can also be used as the compound A according to the present invention.
The sugar ester is not particularly limited, and examples thereof include sugar esters having a structure represented by the following general formula (C).

In the general formula (C), G represents a residue of a monosaccharide or a disaccharide. R ² represents an aliphatic group or an aromatic group. m is the total number of hydroxy groups directly attached to the residue of the monosaccharide or disaccharide, and n is the total number of hydroxy groups directly attached to the residue of the monosaccharide or disaccharide-(OC (= O)). −R ² ) The total number of groups, 3 ≦ m + n ≦ 8, and n ≠ 0.

Specific examples of the monosaccharide represented by G include allose, altrose, glucose, mannose, growth, idose, galactose, tarose, ribose, arabinose, xylose, lyxose and the like.

Specific examples E-1 to E-6 of sugar esters having a structure represented by the general formula (C) having monosaccharide residues are shown below, but the present invention is not limited to these exemplified compounds. do not have.

Specific examples of the disaccharide residue include trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, isotrehalose and the like.

Specific examples F-1 to F-4 of sugar esters having a structure represented by the general formula (C) having disaccharide residues are shown below, but the present invention is not limited to these exemplified compounds. do not have.

In the general formula (C), R ² represents an aliphatic group or an aromatic group. The aliphatic group and the aromatic group may each have a substituent.

The ^{aliphatic group represented by R 2} may be linear, branched, or cyclic, preferably having 1 to 25 carbon atoms, and preferably having 1 to 20 carbon atoms. More preferably, those having 2 to 15 carbon atoms are particularly preferable. Specific examples of the aliphatic group include methyl group, ethyl group, n-propyl group, iso-propyl group, cyclopropyl group, n-butyl group, iso-butyl group, tert-butyl group, amyl group and iso. -Amil group, tert-amyl group, n-hexyl group, cyclohexyl group, n-heptyl group, n-octyl group, bicyclooctyl group, adamantyl group, n-decyl group, tert-octyl group, dodecyl group, hexadecyl group, Examples thereof include an octadecyl group and a didecyl group.

The aromatic group in R ^2, it may be an aromatic hydrocarbon ring group may be an aromatic heterocyclic group, more preferably an aromatic hydrocarbon ring group.
The aromatic hydrocarbon ring group preferably has 6 to 24 carbon atoms, and more preferably 6 to 12 carbon atoms. Specific examples of the aromatic hydrocarbon ring group include groups derived from a benzene ring, a naphthalene ring, an anthracene ring, a biphenyl ring, a terphenyl ring and the like. Of these, groups derived from the benzene ring, naphthalene ring, and biphenyl ring are particularly preferable.
As the aromatic heterocyclic group, a ring containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom is preferable. Specific examples of the aromatic heterocyclic group include a furan ring, a pyrrole ring, a thiophene ring, an imidazole ring, a pyrazole ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a triazole ring, a triazine ring, an indole ring, an indazole ring, and a purine. Ring, thiazoline ring, thiazazole ring, oxazoline ring, oxazole ring, oxazole ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthylidine ring, quinoxaline ring, quinazoline ring, cinnoline ring, pteridine ring, aclysine ring, phenanthrolin ring, phenazine ring. Examples thereof include groups derived from a ring, a tetrazole ring, a benzimidazole ring, a benzoxazole ring, a benzthiazole ring, a benzotriazole ring, a tetrazyneden ring and the like. Of these, groups derived from the pyridine ring, triazine ring, and quinoline ring are particularly preferable.

Further, in the general formula (C), m is the total number of hydroxy groups directly bonded to the residue of the monosaccharide or disaccharide, and n is the total number of hydroxy groups directly bonded to the residue of the monosaccharide or disaccharide. It is the total number of-(OC (= O) -R ^{2) groups.} And although 3 ≦ m + n ≦ 8, it is preferable that 4 ≦ m + n ≦ 8. Also, n ≠ 0. When n is 2 or more, the-(OC (= O) -R ² ) groups may be the same or different from each other.

The sugar ester may contain two or more different substituents in one molecule, and the substituents include (1) an aromatic group and an aliphatic group in one molecule, and (2) different. Two or more aromatic groups can be contained in one molecule, and (3) two or more different aliphatic groups can be contained in one molecule.

It is also preferable to mix and contain two or more types of sugar esters. It is also preferable to simultaneously contain a sugar ester having an aromatic group and a sugar ester containing an aliphatic group.

Hereinafter, preferred examples of the sugar ester represented by the general formula (C) are shown below, but the present invention is not limited to these exemplified compounds.

(Polymer)
Further, the compound A according to the present invention is preferably a polymer having a repeating unit, and for example, a polycondensation ester can be used.
The exemplary compounds 1-1 to 1-23 of the polycondensation ester are shown below. The weight average molecular weights of the illustrated compounds 1-17 to 1-23 shown below are examples, and are not particularly limited thereto.

Hereinafter, specific synthetic examples of the polycondensation ester described above will be described.

(1) Polycondensation ester 1-5
180 g of ethylene glycol, 370 g of phthalic anhydride, 610 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were placed in a 2 L four-necked flask equipped with a thermometer, a stirrer, and a slow-speed cooling tube. The temperature is gradually raised while stirring until the temperature reaches 230 ° C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted ethylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensation ester 1-5. The polycondensation ester 1-5 had an acid value of 0.20 and a weight average molecular weight of 462.

(2) Polycondensation ester 1-14
251 g of 1,2-propylene glycol, 354 g of terephthalic acid, 610 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were placed in a 2 L four-necked flask equipped with a thermometer, a stirrer, and a slow-speed cooling tube, and nitrogen was charged. The temperature is gradually raised in the air stream while stirring until the temperature reaches 230 ° C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensation ester 1-14. The polycondensation ester 1-14 had an acid value of 0.10 and a weight average molecular weight of 491.

(3) Polycondensation ester 1-15
251 g of 1,2-propylene glycol, 354 g of terephthalic acid, 680 g of p-troyl acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were charged into a 2 L four-necked flask equipped with a thermometer, a stirrer, and a slow-speed cooling tube. , Gradually raise the temperature in a nitrogen stream while stirring until it reaches 230 ° C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensation ester 1-15. The polycondensation ester 1-15 had an acid value of 0.30 and a weight average molecular weight of 519.

(4) Polycondensation ester 1-16
180 g of 1,2-propylene glycol, 244 g of phthalic anhydride, 103 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were charged into a 2 L four-necked flask equipped with a thermometer, a stirrer, and a slow-speed cooling tube. The temperature is gradually raised in a nitrogen stream with stirring until the temperature reaches 200 ° C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensation ester 1-16. The polycondensation ester 1-16 had an acid value of 0.10 and a weight average molecular weight of 491.

(5) Polycondensation ester 1-17
251 g of ethylene glycol, 244 g of phthalic anhydride, 120 g of succinic acid, 150 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were charged into a 2 L four-necked flask equipped with a thermometer, a stirrer, and a slow-speed cooling tube. The temperature is gradually raised in a nitrogen stream with stirring until the temperature reaches 200 ° C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted ethylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensation ester 1-17. The polycondensation ester 1-17 had an acid value of 0.50 and a weight average molecular weight of 1230.

(6) Polycondensation ester 1-18
The reaction conditions (reaction time, reaction temperature) were changed by the same production method as the polycondensation ester 1-17 to obtain a polycondensation ester 1-18 having an acid value of 0.10 and a weight average molecular weight of 600.

(7) Polycondensation ester 1-19
251 g of 1,2-propylene glycol, 103 g of terephthalic acid, 244 g of adipic acid, 610 g of benzoic acid, 0.191 g of tetraisopropyl titanate as an esterification catalyst, and a 2 L four-necked flask equipped with a thermometer, a stirrer, and a slow-speed cooling tube. The temperature is gradually raised in a nitrogen stream while stirring until the temperature reaches 230 ° C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensation ester 1-19. The polycondensation ester 1-19 had an acid value of 0.10 and a weight average molecular weight of 3600.

(8) Polycondensation ester 1-20
The reaction conditions (reaction time, reaction temperature) were changed by the same production method as the polycondensation ester 1-19 to obtain a polycondensation ester 1-20 having an acid value of 0.10 and a weight average molecular weight of 450.

(Multivalent alcohol ester)
A polyhydric alcohol ester can also be used as the compound A according to the present invention.

The polyhydric alcohol ester is a compound composed of a divalent or higher aliphatic polyhydric alcohol and an ester of a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. The polyhydric alcohol ester is preferably an aliphatic polyhydric alcohol ester having 2 to 20 valences.

The polyhydric alcohol preferably used in the present invention has a structure represented by the following general formula (D).

In the general formula (D), R ¹¹ represents an n-valent organic group. The OH group represents an alcoholic and / or phenolic hydroxy group. n is a positive integer greater than or equal to 2.

The preferred polyhydric alcohol is not particularly limited, but for example, adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol and tripropylene. Glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, Examples thereof include hexanetriol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol and the like.
Of these, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

The monocarboxylic acid used for the polyhydric alcohol ester is not particularly limited, and known aliphatic monocarboxylic acids, cyclic aliphatic monocarboxylic acids, aromatic monocarboxylic acids and the like can be used. It is preferable to use an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid in terms of improving moisture permeability and retention.

Examples of preferable monocarboxylic acids include, but are not limited to, the present invention.

As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. The aliphatic monocarboxylic acid is more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms. It is preferable to add acetic acid because the compatibility with cellulose acetate increases, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.

Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, capric acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecyl acid, lauric acid, tridecyl acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanic acid, araquinic acid, bechenic acid, lignoseric acid, cellotic acid, heptacosanoic acid, montanic acid, melisic acid, laxel acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid.

Preferred cyclic aliphatic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof.

Preferred aromatic monocarboxylic acids include those in which 1 to 3 alkoxy groups such as alkyl group, methoxy group or ethoxy group are introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, biphenylcarboxylic acid and naphthalincarboxylic acid. Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as acids and tetralincarboxylic acids, or derivatives thereof. Of these, benzoic acid is particularly preferable.

The weight average molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably in the range of 300 to 1500, and more preferably in the range of 350 to 750. A larger molecular weight is preferable because it is less likely to volatilize, and a smaller molecular weight is preferable in terms of moisture permeability.

The carboxylic acid used in the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Further, all the OH groups in the polyhydric alcohol may be esterified, or some of them may be left as OH groups.

Specific compounds 2-1 to 2-10 of the polyhydric alcohol ester will be illustrated below.

(Glycolic acid esters)
Further, in the present invention, glycolic acid esters (glycolate compounds) can be used as one of the polyhydric alcohol esters.

The glycolate compound applicable to the present invention is not particularly limited, but alkylphthalyl alkyl glycolates can be preferably used.

Examples of alkylphthalyl alkyl glycolates include methylphthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propylphthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, and methyl phthalyl. Ethyl Glycolate, Ethylphthalyl Methyl Glycolate, Ethylphthalylpropyl Glycolate, Methylphthalylbutyl Glycolate, Ethylphthalylbutyl Glycolate, Butylphthalyl Methyl Glycolate, Butylphthalyl EthylGlycolate, Procphthalylbutyl Glycolate, butylphthalylpropylglycolate, methylphthalyloctylglycolate, ethylphthalyloctylglycolate, octylphthalylmethylglycolate, octylphthalylethylglycolate and the like can be mentioned, with preference given to ethphthalyl ethyl glycolate. Is.

The polyhydric alcohol ester used in the present invention can be synthesized according to a commonly known synthetic method.

《Polyimide film》
The polyimide resin composition of the present invention can be suitably used as a polyimide film material.

<Additive>
In addition to the polyimide resin composition of the present invention, the polyimide film can contain various additives for the purpose of imparting various functions.
The additives applicable to the present invention are not particularly limited, and are, for example, a phase difference increasing agent, a wavelength dispersion improving agent, a deterioration inhibitor, an ultraviolet absorber, a matting agent, and a plasticizer as long as the objective effects of the present invention are not impaired. Agents and the like can be used.
The typical additives applicable to the polyimide film are shown below.

(UV absorber)
It is preferable that the polyimide film contains an ultraviolet absorber from the viewpoint of improving light resistance. The ultraviolet absorber aims to improve the light resistance by absorbing ultraviolet rays of 400 nm or less, and particularly preferably has a light transmittance in the range of 0.1 to 30% at a wavelength of 370 nm. It is preferably in the range of 1 to 20%, more preferably in the range of 2 to 10%.

Examples of the ultraviolet absorber include oxybenzophenone-based compounds, benzotriazole-based compounds, salicylate-based compounds, benzophenone-based compounds, cyanoacrylate-based compounds, nickel complex salt-based compounds, and the like, but benzotriazole-based compounds with less coloring. Compounds are preferred. Further, the ultraviolet absorbers described in JP-A-10-182621 and JP-A-8-337574, and the polymer ultraviolet absorbers described in JP-A-6-148430 are also preferably used. The ultraviolet absorber preferably used in the present invention is a benzotriazole-based ultraviolet absorber, a benzophenone-based ultraviolet absorber, and a triazine-based ultraviolet absorber, and particularly preferably a benzotriazole-based ultraviolet absorber and a benzophenone-based ultraviolet absorber.

For example, examples of benzotriazole-based ultraviolet absorbers useful for polyimide films include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole and 2- (2'-hydroxy-3', 5'-di. -T-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-di-t -Butylphenyl) -5-chlorobenzotriazole, 2- [2'-hydroxy-3'-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidemethyl) -5'-methylphenyl] benzotriazole, 2 , 2-Methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazole-2-yl) phenol], 2- (2'-hydroxy-3'-t-butyl -5'-Methylphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazole-2-yl) -6- (straight chain and side chain dodecyl) -4-methylphenol, octyl-3- [3- [3- t-Butyl-4-hydroxy-5- (chloro-2H-benzotriazole-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-t-butyl-4-hydroxy-5- (5-chloro-) Examples include, but are not limited to, a mixture of 2H-benzotriazole-2-yl) phenyl] propionate.
Further, as commercially available products, "TINUVIN 109", "TINUVIN 171", "TINUVIN 326", and "TINUVIN 328" (trade names, manufactured by BASF Japan Ltd.) are preferable. Can be used. Of these, halogen-free ones are preferable.

In addition, a disk-shaped compound such as a compound having a 1,3,5-triazine ring is also preferably used as an ultraviolet absorber.

The polyimide film preferably contains two or more types of ultraviolet absorbers.

The method of adding the UV absorber is to dissolve the UV absorber in an alcohol such as methanol, ethanol or butanol, an organic solvent such as methylene chloride, methyl acetate, acetone or dioxolane, or a mixed solvent thereof, and then add the UV absorber to the dope. Alternatively, it may be added directly into the dope composition.

The amount of the UV absorber used is not uniform depending on the type of UV absorber, usage conditions, etc., but when the dry film thickness of the polyimide film is within the range of 15 to 50 μm, it is 0.5 with respect to the polyimide film. The range of 10% by mass is preferable, and the range of 0.6 to 4% by mass is more preferable.

(Deterioration inhibitor)
Deterioration agents such as antioxidants, peroxide decomposing agents, radical polymerization inhibitors, metal inactivating agents, acid trapping agents, amines and the like may be added to the polyimide film. Deterioration inhibitors are described in, for example, JP-A-3-199201, JP-A-5-197073, JP-A-5-194789, JP-A-5-271471 and JP-A-6-107854. The compounds described in paragraphs 0108 to 0119 of the 2010-271619 publication can be preferably used.
The amount of the deterioration inhibitor added is a polyisoimide resin composition solution (polyisoimide resin composition solution) used for producing the film from the viewpoint that the effect of the addition of the deterioration inhibitor is exhibited and the bleed-out (bleeding out) of the deterioration inhibitor to the film surface is suppressed. The dope) is preferably in the range of 0.01 to 1% by mass, and more preferably in the range of 0.01 to 0.2% by mass.
Examples of particularly preferable antioxidants include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

(Mat agent fine particles)
It is preferable to add fine particles as a matting agent to the polyimide film.
The matting fine particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and Calcium silicate can be mentioned. Among these matting fine particles, those containing silicon are preferable in that the turbidity (haze) is low, and silicon dioxide is particularly preferable.
The fine particles of silicon dioxide preferably have a primary average particle size in the range of 1 to 20 nm and an apparent specific gravity of 70 g / L or more. The primary average particle size in the range of 5 to 16 nm is more preferable from the viewpoint of reducing the haze of the polyimide film. The apparent density is more preferably in the range of 90 to 200 g / L, and particularly preferably in the range of 100 to 200 g / L. The larger the apparent specific gravity, the higher the concentration of the dispersion, which is preferable because the haze and aggregates are improved.

These fine particles usually form secondary particles having an average particle size in the range of 0.05 to 2.0 μm. The secondary particles exist as agglomerates of primary particles in the polyimide film, and form irregularities of 0.05 to 2.0 μm on the surface of the polyimide film.
The secondary average particle size is preferably in the range of 0.05 to 1.0 μm, more preferably in the range of 0.1 to 0.7 μm, and particularly preferably in the range of 0.1 to 0.4 μm. The primary and secondary particle sizes were determined by observing the fine particles in the polyimide film with a scanning electron microscope and using the diameter of the circle circumscribing the particles as the particle size. In addition, 200 particles are observed at different locations, and the average value thereof is used as the average particle size.

As the fine particles of silicon dioxide, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600 (all manufactured by Nippon Aerosil Co., Ltd.) can be used. The fine particles of zirconium oxide are commercially available, for example, Aerosil R976 and R811 (all manufactured by Nippon Aerosil Co., Ltd.) and can be used.
Among these, Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / L or more, and have a friction coefficient while keeping the haze of the polyimide film low. It is particularly preferable because it has a large effect of lowering.

The matting fine particles are preferably prepared by the following method and applied to a polyimide film. That is, a matting agent fine particle dispersion liquid in which a solvent and matting agent fine particles are stirred and mixed is prepared in advance, and this matting agent fine particle dispersion liquid is added to a separately prepared various additive solutions having a polyisoimide concentration of less than 5% by mass and stirred. A method of further mixing with polyisoimide after dissolution is preferable.
Since the surface of the matting fine particles is hydrophobized, when a hydrophobic additive is added, the additive is adsorbed on the surface of the matting fine particles, and agglomerates of the additives form as nuclei. Likely to happen.
Therefore, by mixing the relatively hydrophilic additive with the matting fine particle dispersion in advance and then mixing the hydrophobic additive, it is possible to suppress the aggregation of the additive on the matting surface, and haze. Is low, and there is little light leakage in the black display when incorporated into a liquid crystal display device, which is preferable.

It is preferable to use an in-line mixer for mixing the matting fine particle dispersant and the additive solution and mixing the polyisoimide-doped solution.
The concentration of silicon dioxide when the fine particles of silicon dioxide are mixed with a solvent or the like and dispersed is preferably in the range of 5 to 30% by mass, more preferably in the range of 10 to 25% by mass, and in the range of 15 to 20% by mass. Is particularly preferable. The higher the dispersion concentration, the lower the turbidity with respect to the same amount of addition, and the haze and the generation of agglomerates can be suppressed, which is preferable. The amount of the matting agent added in the final polyisoimide dope solution is preferably in the range of 0.001 to 1.0% by mass, more preferably in the range of 0.005 to 0.5% by mass, and 0. The range of 01 to 0.1% by mass is particularly preferable.

(Peeling accelerator)
A peeling accelerator may be added to the polyimide film of the present invention in order to improve the peelability during film production.

Many of the additives that reduce the peeling resistance of the polyimide film have a remarkable effect on the surfactant, and the preferable peeling accelerator is a phosphate ester-based surfactant, a carboxylic acid or a carboxylic acid salt-based surfactant. Agents, sulfonic acid or sulfonate-based surfactants, and sulfate ester-based surfactants are effective. Further, a fluorine-based surfactant in which a part of hydrogen atoms bonded to the hydrocarbon chain of the above-mentioned surfactant is replaced with a fluorine atom is also effective. The peeling accelerator is illustrated below.

RZ-1 C ₈ H ₁₇ OP (= O) (OH) ₂
RZ-2 C ₁₂ H ₂₅ OP (= O) (OK) ₂
RZ-3 C ₁₂ H ₂₅ OCH ₂ CH ₂ OP (= O) (OK) ₂
RZ-4 C ₁₅ H ₃₁ (OCH ₂ CH ₂ ) ₅ OP (= O) (OK) ₂
RZ-5 {C ₁₂ H ₂₅ O (CH ₂ CH ₂ O) ₅ } ₂ P (= O) -OH
RZ-6 {C ₁₈ H ₃₅ (OCH ₂ CH ₂ ) ₈ O} ₂ P (= O) -ONH ₄
RZ-7 (t-C ₄ H ₉ ) _3- C ₆ H _2- OCH ₂ CH ₂ OP (= O) (OK) ₂
RZ-8 (iso-C ₉ H _19- C ₆ H _4- O- (CH ₂ CH ₂ O) _5- P (= O) (OK) (OH)
RZ-9 C ₁₂ H ₂₅ SO ₃ Na
RZ-10 C ₁₂ H ₂₅ OSO ₃ Na
RZ-11 C ₁₇ H ₃₃ COOH
RZ-12 C ₁₇ H ₃₃ COOH ・ N (CH ₂ CH ₂ OH) ₃
RZ-13 iso-C ₈ H _17- C ₆ H _4- O- (CH ₂ CH ₂ O) _3- (CH ₂ ) ₂ SO ₃ Na
RZ-14 (iso-C ₉ H ₁₉ ) _2- C ₆ H _3- O- (CH ₂ CH ₂ O) _3- (CH ₂ ) ₄ SO ₃ Na
RZ-15 Sodium triisopropylnaphthalene sulphonate RZ-16 Sodium tri-t-butylnaphthalene sulphonate RZ-17 C ₁₇ H ₃₃ CON (CH ₃ ) CH ₂ CH ₂ SO ₃ Na
RZ-18 C ₁₂ H _25- C ₆ H ₄ SO ₃・ NH ₄

The amount of the peeling accelerator added is preferably in the range of 0.05 to 5% by mass, more preferably in the range of 0.1 to 2% by mass, and in the range of 0.1 to 0.5% by mass with respect to the polyimide. Is most preferable.

Other additives such as inorganic fine particles and a retardation adjuster can be used for the polyimide film, if necessary.

<Manufacturing method of polyimide film>
Hereinafter, a method for producing a polyimide film containing the polyimide resin composition of the present invention will be described as a specific example.

The method for producing a polyimide film includes a step of preparing a dope containing polyisoimide, compound A, and a solvent, a step of casting the dope onto a support to form a film, a step of peeling the film from the support, and a step of peeling. Includes a step of drying the polyimide film.

As a method for producing a polyimide film, a step of preparing a dope containing polyisoimide, compound A and a solvent (dope preparation step), a step of casting the dope on a support to form a film (casting step), and a step of casting the dope on a support. A step of peeling the film from the support (peeling step), a step of drying the obtained cast film to obtain a film (first drying step), a step of stretching the dried film (stretching step), and a step after stretching. It is more preferable to include a step of further drying the film (second drying step), a step of winding the obtained polyimide film (winding step), a step of heat-treating the film to imidize it (heating step), and the like. ..

Hereinafter, each step will be specifically described.

(Dope preparation process)
As a method for producing a polyimide film, it is preferable that compound A is added to a solution of soluble polyisoimide in a solvent to prepare a dope, and the dope is used to form a film by a solution casting film forming method.

As the solvent, it is preferable to use a low boiling point solvent having a boiling point of 80 ° C. or lower as the main solvent because the film manufacturing process temperature (particularly the drying temperature) can be reduced and the heat shrinkage rate can be reduced.
Here, "used as the main solvent" means that 55% by mass or more is used with respect to the total amount of the solvent in the case of a mixed solvent, preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably. Is to be used in an amount of 90% by mass or more. Of course, if used alone, it will be 100% by mass.

The low boiling solvent may be any one that dissolves polyimide and other additives at the same time. For example, the chlorine-based solvent is dichloromethane, and the non-chlorine-based solvent is methyl acetate, ethyl acetate, amyl acetate, acetone, etc. Methyl ethyl ketone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, 1,3- Difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2, Examples thereof include 2,3,3,3-pentafluoro-1-propanol, nitroethane, methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol and the like.

Among the above solvents, low boiling point solvents having a boiling point of 80 ° C. or lower include dichloromethane (40 ° C.), ethyl acetate (77 ° C.), methyl ethyl ketone (79 ° C.), tetrahydrofuran (66 ° C.), and acetone (56.5 ° C.). , And 1,3-dioxolane (75 ° C.) are preferably contained as the main solvent (in parentheses, each represents a boiling point).

Further, as the solvent contained in the case of the mixed solvent, as long as it can dissolve the polyimide according to the present invention, it can be used within a range that does not impair the effect of the present invention, and as a solvent other than the above-mentioned ones, For example, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N-diethylformamide, N-methylcaprolactam, hexamethylphosphoramide, tetra. Methylene sulfone, dimethyl sulfoxide, m-cresol, phenol, p-chlorophenol, 2-chloro-4-hydroxytoluene, diglime, triglime, tetraglime, dioxane, γ-butyrolactone, dioxolane, cyclopentanone, epsilon caprolactam, chloroform, etc. Can be used, and two or more types may be used in combination. In addition to these solvents, a poor solvent such as hexane, heptane, benzene, toluene, xylene, chlorobenzene, or o-dichlorobenzene may be used to the extent that the polyimide and compound A according to the present invention do not precipitate.

Further, an alcohol solvent can also be used. It is preferable that the alcohol solvent is selected from methanol, ethanol and butanol from the viewpoint of improving the peelability and enabling high-speed casting. Of these, it is preferable to use methanol or ethanol. Higher proportions of alcohol in the dope gels the web, facilitating delamination from the metal support.

For dissolution of polyimide and other additives, a method performed at normal pressure, a method performed below the boiling point of the main solvent, a method performed by pressurizing above the boiling point of the main solvent, JP-A-9-955544, JP-A-9- Various melting methods can be used, such as the method performed by the cooling melting method described in JP-A-95557 or JP-A-9-95538, and the method performed at high pressure described in JP-A-11-21379.

The prepared dope is guided to a filter by a liquid feed pump or the like and filtered. For example, when the main solvent of the dope is dichloromethane, the gel-like foreign matter in the dope can be removed by filtering the dope at a temperature of + 5 ° C. or higher at a boiling point of the dichloromethane at 1 atm. The preferred temperature is in the range of 45-120 ° C, more preferably in the range of 45-70 ° C, and even more preferably in the range of 45-55 ° C.

Further, as the raw material of the resin used for the dope preparation, those in which polyimide and other compounds are pelletized in advance can also be preferably used.

(Collapse film forming process)
The prepared dope is pumped onto a die through a liquid feed pump (eg, a pressurized metering gear pump) and transferred indefinitely on a metal support such as a stainless belt or a rotating metal drum. Spread the dope from the die to the position.

The metal support in casting is preferably a mirror-finished surface, and the support includes a stainless steel belt, a drum whose surface is plated with a casting, a stainless belt, a stainless steel belt, or the like. It is preferably used. The width of the cast can be in the range of 1 to 4 m, preferably in the range of 1.5 to 3 m, more preferably in the range of 2 to 2.8 m. The support does not have to be made of metal, for example, polyethylene terephthalate (PET) film, polyethylene naphthalate (PEN) film, polybutylene terephthalate (PBT) film, nylon 6 film, nylon 6,6 film, polypropylene film. , A belt such as polytetrafluoroethylene can be used. When a polyimide film is used as a flexible substrate, the polyimide may be wound together with the metal support.

The traveling speed of the metal support is not particularly limited, but is usually 5 m / min or more, preferably in the range of 10 to 180 m / min, and particularly preferably in the range of 80 to 150 m / min. The higher the traveling speed of the metal support, the easier it is for companion gas to be generated, and the more remarkable the occurrence of film thickness unevenness due to disturbance.
Here, the traveling speed of the metal support is the moving speed of the outer surface of the metal support.

The die has a shape that gradually becomes thinner toward the discharge port in a cross section perpendicular to the width direction. Specifically, the die usually has tapered surfaces on the downstream side and the upstream side in the traveling direction of the lower portion, and a discharge port is formed in a slit shape between the tapered surfaces. A metal die is preferably used, and specific examples thereof include stainless steel and titanium. In the present invention, when producing films having different thicknesses, it is not necessary to change to dies having different slit gaps.

It is preferable to use a pressure die that can adjust the slit shape of the die base portion and can easily make the film thickness uniform. The pressure die includes a coat hanger die, a T die, and the like, and any of them is preferably used. Even when films of different thicknesses are continuously produced, the discharge rate of the die is maintained at a substantially constant value. Therefore, when a pressure die is used, conditions such as extrusion pressure and shear rate are also omitted. It is maintained at a constant value. Further, in order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the doping amount may be divided and laminated.

(Solvent evaporation process)
The solvent evaporation step is a pre-drying step performed on the metal support, in which the cast film is heated on the metal support to evaporate the solvent.

To evaporate the solvent, for example, a method of blowing heating air from the casting film side and the back side of the metal support with a dryer, a method of transferring heat from the back surface of the metal support with a heating liquid, and a method of transferring heat from the front and back by radiant heat. And so on. A method of appropriately selecting and combining them is also preferable. The surface temperature of the metal support may be the same as a whole or may differ depending on the position. The temperature of the heating air is preferably in the range of 10 to 220 ° C.

The temperature of the heating air (drying temperature) is preferably 200 ° C. or lower, more preferably 140 ° C. or lower, and even more preferably 120 ° C. or lower.

In the solvent evaporation step, it is preferable to dry the casting film until the residual solvent amount is within the range of 10 to 150% by mass from the viewpoint of the peelability of the casting film and the transportability after peeling.

In the present invention, the amount of residual solvent can be expressed by the following formula.

Residual solvent amount (mass%) = {(MN) / N} x 100
Here, M is the mass of the casting film (film) at a predetermined time point, and N is the mass when the film is dried at 200 ° C. for 3 hours from the predetermined time point. In particular, M when calculating the residual solvent amount achieved in the solvent evaporation step is the mass of the cast film immediately before the peeling step.

(Peeling process)
The cast film in which the solvent has evaporated on the metal support is peeled off at the peeling position.

The peeling tension when peeling the metal support and the casting film is usually in the range of 60 to 400 N / m, but if wrinkles are likely to occur during peeling, the metal support is peeled at a tension of 190 N / m or less. Is preferable.

In the present invention, the temperature at the peeling position on the metal support is preferably in the range of −50 to 60 ° C, more preferably in the range of 10 to 40 ° C, and in the range of 15 to 40 ° C. Is the most preferable.

The peeled film may be sent directly to the stretching step, or may be sent to the stretching step after being sent to the first drying step so as to achieve a desired residual solvent amount. In the present invention, from the viewpoint of stable transport in the stretching step, it is preferable that the film is sequentially fed to the first drying step and the stretching step after the peeling step.

(1st drying step)
The first drying step is a drying step of heating the film and further evaporating the solvent. The drying means is not particularly limited, and for example, hot air, infrared rays, a heating roller, microwaves, or the like can be used. From the viewpoint of convenience, it is preferable to dry the film with hot air or the like while transporting the film with rollers arranged in a staggered pattern. The drying temperature is preferably in the range of 30 to 200 ° C. in consideration of the amount of residual solvent, the expansion / contraction rate during transportation, and the like.

The drying temperature is preferably 200 ° C. or lower, more preferably 140 ° C. or lower, and even more preferably 120 ° C. or lower.

By lowering the drying temperature, the heat shrinkage rate of the film can be increased.

(Stretching process)
By stretching the film peeled from the metal support, the film thickness, flatness, orientation, etc. of the film can be controlled.
In the method for producing a polyimide film, it is preferable to stretch it in the longitudinal direction or the width direction.

The stretching operation may be performed in multiple stages. Further, when biaxial stretching is performed, simultaneous biaxial stretching may be performed, or biaxial stretching may be performed step by step. In this case, the term “stepwise” means, for example, that stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any of the steps. Is also possible.

That is, for example, the following stretching step is also possible.
(I) Stretching in the longitudinal direction → Stretching in the width direction → Stretching in the longitudinal direction → Stretching in the longitudinal direction (ii) Stretching in the width direction → Stretching in the width direction → Stretching in the longitudinal direction → Stretching in the longitudinal direction

Further, the simultaneous biaxial stretching includes a case where the drawing is performed in one direction and the other is contracted by relaxing the tension. The preferred draw ratio for simultaneous biaxial stretching can be in the range of 1.01 to 1.5 times in both the width direction and the longitudinal direction.

The amount of residual solvent at the start of stretching is preferably in the range of 0.1 to 200% by mass. When the amount of residual solvent is 0.1% by mass or more, the effect of improving the flatness by stretching can be obtained, and when it is 200% or less, stretching is easy.

In the method for producing a polyimide film, the film may be stretched in the longitudinal direction or the width direction, preferably in the width direction so that the film thickness after stretching is within a desired range. It is preferable to stretch the polyimide film in a temperature range of (Tg-200) to (Tg + 100) ° C. with respect to the glass transition temperature (Tg). When stretched in the above temperature range, the stretching stress can be reduced and the haze becomes low. Further, it is possible to obtain a polyimide film which suppresses the occurrence of breakage and has excellent flatness and colorability of the polyimide film itself. The stretching temperature is more preferably in the range of (Tg-150) to (Tg + 50) ° C.

In the method for producing a polyimide film, a self-supporting film peeled from a support can be stretched in the longitudinal direction by controlling the traveling speed with a stretching roller.

In order to stretch in the width direction, for example, the width of both ends of the width of the film is held by a clip or a pin in the width direction by performing a total drying treatment or a part of the drying treatment as shown in Japanese Patent Application Laid-Open No. 62-46625. A method of drying while drying (called a tenter method), in particular, a tenter method using a clip is preferably used.

It is preferable that the film stretched in the longitudinal direction or the unstretched film is introduced into the tenter with both ends in the width direction gripped by the clip, and is stretched in the width direction while traveling together with the tenter clip.

When stretching in the width direction, it is preferable to stretch the film at a stretching speed in the range of 50 to 1000% / min in the width direction from the viewpoint of improving the flatness of the film. When the stretching speed is 50% / min or more, the flatness is improved and the film can be processed at high speed, which is preferable from the viewpoint of production suitability. When the stretching speed is 1000% / min or less, the film breaks. It can be processed without any problem, which is preferable.
A more preferred stretching rate is in the range of 100-500% / min.

The stretching rate is defined by the following formula.

Stretching rate (% / min) = [(d ₁ / d ₂ ) -1] × 100 (%) / t
Here, d ₁ is the width dimension of the resin film after stretching in the stretching direction, d ₂ is the width dimension of the film before stretching in the stretching direction, and t is the time (min) required for stretching.

In the stretching step, holding / relaxation is usually performed after stretching. That is, in this step, it is preferable to perform a stretching step of stretching the film, a holding step of holding the film in a stretched state, and a relaxing step of relaxing the film in the stretching direction in these orders. In the holding step, the stretching at the stretching ratio achieved in the stretching step is held at the stretching temperature in the stretching step. In the relaxation step, the stretching in the stretching step is held in the holding step, and then the tension for stretching is released to relax the stretching. The relaxation step may be performed at a temperature equal to or lower than the stretching temperature in the stretching step.

(Second drying step)
Then, the stretched film is heated and dried. When the film is heated by hot air or the like, a means for preventing the mixing of used hot air by installing a nozzle capable of exhausting used hot air (air containing a solvent or wet air) is also preferably used. The hot air temperature is more preferably in the range of 40 to 350 ° C. The drying time is preferably about 5 seconds to 30 minutes, more preferably 10 seconds to 15 minutes.

Further, the heating and drying means is not limited to hot air, and for example, infrared rays, heating rollers, microwaves and the like can be used. From the viewpoint of convenience, it is preferable to dry the film with hot air or the like while transporting the film with rollers arranged in a staggered pattern. The drying temperature is preferably in the range of 40 to 150 ° C. from the viewpoint that heat shrinkage tends to be large. Further, it is more preferably in the range of 40 to 120 ° C.

In the second drying step, it is preferable to dry the film until the residual solvent amount becomes 0.5% by mass or less.

(Winding process)
The winding step is a step of winding the obtained polyimide film and cooling it to room temperature.
The winder may be a generally used one, and can be wound by a winding method such as a constant tension method, a constant torque method, a taper tension method, or a program tension control method with a constant internal stress.

The thickness of the polyimide film is not particularly limited, and is preferably in the range of, for example, 1 to 200 μm, particularly 1 to 100 μm.

In the winding step, both ends of the polyimide film sandwiched between tenter clips and the like when stretched and conveyed may be slit. It is preferable that the slit end of the polyimide film is finely cut within a width range of 1 to 30 mm, then dissolved in a solvent and reused as a return material.

Each step from the solvent evaporation step to the winding step described above may be carried out in an air atmosphere or an inert gas atmosphere such as nitrogen gas. Further, each step, particularly the drying step and the stretching step, is carried out in consideration of the explosive limit concentration of the solvent in the atmosphere.

(Heating process)
After the winding step, a heating step is performed in which the polyimide film dried in the second drying step is further heat-treated in order to imidize the polyisoimide and dislocate it to the polyimide to improve the mechanical properties.

The second drying step may also serve as a heating step.

The heating means is performed by using known means such as hot air, an electric heater, and a microwave. As the electric heater, the infrared heater described above can be used.

In the heating step, if the polyimide film is rapidly heated, problems such as an increase in surface defects occur. Therefore, it is preferable to appropriately select the heating method. Further, the heating step is preferably performed in a low oxygen atmosphere.

If the heating temperature in the second drying step and the heating step exceeds 450 ° C., the energy required for heating becomes very large, which increases the manufacturing cost and further increases the environmental load. Therefore, the heating temperature is 450 ° C. It is preferable to make the following.

After the winding step, before or after the heating step, a step of slitting the widthwise end portion of the polyimide film, a step of removing static electricity from the polyimide film when it is charged, and the like are further performed. May be.

The imidization of polyisoimide may be carried out in any of a first drying step, a second drying step, and a heating step.

<Shape of polyimide film>
The polyimide film is preferably long, specifically, has a length within the range of about 100 to 10,000 m, and is wound into a roll. The width of the polyimide film is preferably 1 m or more, more preferably 1.4 m or more, and particularly preferably in the range of 1.4 to 4 m.

<Physical characteristics of polyimide film>
(Elastic modulus)
The polyimide film preferably has an elastic modulus in the range of 3 to 7 GPa, and more preferably in the range of 4 to 7 GPa.
The elastic modulus is obtained by cutting out a strip-shaped test piece having a flow direction (MD direction) and a width direction (TD direction) of 100 mm × 10 mm, respectively, and using a tensile tester (Shimadzu Seisakusho “Autograph (R): Model name AG-”. The tensile elastic modulus is measured in each of the MD direction and the TD direction using 5000A ”), and is used as the average value of the obtained tensile elastic moduli in the MD direction and the TD direction.

(Total light transmittance)
The polyimide film is preferably transparent, and as a measure of transparency, the total light transmittance when a sample having a thickness of 25 μm is prepared is preferably 80% or more. It is more preferably 85% or more, and further preferably 90% or more. The higher the total light transmittance, the higher the transparency, which is preferable.

The total light transmittance of the polyimide film is measured by measuring one polyimide film sample whose humidity is adjusted for 24 hours in an air-conditioned room at 23 ° C. and 55% RH according to JIS K 7375-2008. For the measurement, the light transmittance in the visible light region (range of 400 to 700 nm) is measured using a spectrophotometer U-3300 of Hitachi High-Technologies Corporation.

(Yellow index value (YI value))
The polyimide film is preferably a colorless polyimide film. As a guideline for being colorless, the yellow index value (YI value) is preferably 4.0 or less. It is more preferably in the range of 0.3 to 2.0, and particularly preferably in the range of 0.3 to 1.6. The smaller the yellow index value (YI value), the less the coloring, which is preferable.

The yellow index value can be adjusted by selecting the type of polyimide.

The yellow index value can be obtained according to the YI (yellow index: yellowish index) of the film defined in JIS K 7103.

As a method for measuring the yellow index value, a film sample is prepared, and a light source specified in JIS Z 8701 is used using a spectrophotometer U-3300 of Hitachi High-Technologies Corporation and an attached saturation calculation program. The tristimulus values X, Y, and Z of the color are obtained, and the yellow index value is obtained according to the definition of the following formula.

Yellow index (YI) = 100 x (1.28X-1.06Z) / Y

<Use of polyimide film>
The polyisoimide obtained in the present invention can be made into an almost colorless and transparent polyimide resin molded product having various shapes by the above-mentioned various molding methods. This makes it possible to apply it not only to typical films of polyimide but also to a wide range of applications. For example, flexible solar cell members, display members, IC packaging trays, IC manufacturing process trays, IC sockets, wafer carriers, connectors, sockets, hard disk carriers, liquid crystal display carriers, crystal oscillator manufacturing trays, copier separation claws. , Copier insulation bearings, copier gears, thrust washers, transmission rings, piston rings, oil seal rings, bearing retainers, pump gears, conveyor chains, stretch machine slide bushes, heat-resistant insulating tape, heat-resistant adhesive tape, high-density magnetic It can be used for manufacturing recording bases, capacitors, films for flexible printed substrates, and the like. It is also used for manufacturing structural members reinforced with, for example, glass fiber or carbon fiber, bobbins of small coils, or molded products of terminal insulating tubes.
The polyimide film can be preferably used as a film member of an image display device. The applicable device is not particularly limited, and examples thereof include an organic electroluminescence (EL) image display device, a liquid crystal image display device (LCD), an organic photoelectric conversion device, a touch panel, a polarizing plate, and a retardation film. .. From the viewpoint that the effect of the present invention can be obtained more efficiently, the polyimide film is more preferably used as a base material (transparent substrate) of the transparent conductive film used for a touch panel.

(Transparent conductive film)
The transparent conductive film is composed of at least a polyimide film (transparent substrate) and a transparent conductive layer.

As an example of the configuration of the transparent conductive film, as shown in FIG. 1, the transparent conductive film 1 is provided with a surface protective layer 3 and a transparent conductive layer 4 laminated in this order on a polyimide film (substrate) 2. Further, a surface protective layer 3 is further provided on the other surface of the polyimide film (base material) 2.

In the transparent conductive film, the resistance value of the transparent conductive layer is 0.01 to 150 Ω / sq. It is preferably within the range of. More preferably, the resistance value of the transparent conductive layer is 0.1 to 100 Ω / sq. Is within the range of. The resistance value of the transparent conductive layer is 0.01Ω / sq. With the above, durability against keystrokes is obtained, and the resistance value is 150 Ω / sq. The following is preferable from the viewpoint of suppressing curl.

Further, the transparent conductive layer may satisfy the above resistance value, but preferably contains a copper mesh, copper is less likely to cause a migration phenomenon than other metals, and is preferable from the viewpoint of suppressing disconnection at the time of keystroke.

(1) Metal nanowires Metal nanowires are conductive substances that are made of metal, have a needle-like or thread-like shape, and have a diameter of nanometers. The metal nanowires may be linear or curved. By using a transparent conductive layer made of such metal nanowires, the metal nanowires have a mesh shape, so that a good electric conduction path can be formed even with a small amount of metal nanowires. , A transparent conductive film having low electrical resistance can be obtained. Further, since the metal nanowires have a mesh shape, an opening can be formed in the gap between the meshes to obtain a transparent conductive film having high light transmittance.

The ratio of the thickness d to the length L (aspect ratio: L / d) of the metal nanowire is preferably in the range of 10 to 100,000, more preferably in the range of 50 to 100,000, and particularly preferably. Is in the range of 100 to 10,000. When metal nanowires having such a large aspect ratio are used, the metal nanowires can cross each other well, and a small amount of metal nanowires can exhibit high conductivity. As a result, a transparent conductive film having high light transmittance can be obtained.

The "thickness of the metal nanowire" means the diameter of the metal nanowire when the cross section is circular, the minor diameter of the metal nanowire when it is elliptical, and when it is polygonal. Means the longest diagonal. The thickness and length of the metal nanowires can be confirmed by a scanning electron microscope or a transmission electron microscope.

The thickness of the metal nanowires is preferably less than 500 nm, more preferably less than 200 nm, particularly preferably in the range of 10 to 100 nm, and most preferably in the range of 10 to 50 nm. Within such a range, a transparent conductive layer having high light transmittance can be formed.

The length of the metal nanowires is preferably in the range of 2.5 to 1000 μm, more preferably in the range of 10 to 500 μm, and particularly preferably in the range of 20 to 100 μm. Within such a range, a transparent conductive film having high conductivity can be obtained.

As the metal constituting the metal nanowire, any suitable metal can be used as long as it is a highly conductive metal. Examples of the metal constituting the metal nanowire include silver, gold, copper, nickel and the like. Further, a material obtained by plating (for example, gold plating) these metals may be used. Of these, silver or copper is preferable from the viewpoint of conductivity.

Any suitable method can be adopted as the method for producing the metal nanowires. For example, a method of reducing silver nitrate in a solution, a method of applying an applied voltage or an electric current to the surface of the precursor from the tip of the probe, pulling out the metal nanowire at the tip of the probe, and continuously forming the metal nanowire. Be done. In the method of reducing silver nitrate in a solution, silver nanowires can be synthesized by liquid-phase reduction of a silver salt such as silver nitrate in the presence of a polyol such as ethylene glycol and polyvinylpyrrolidone.

Uniform size silver nanowires are available, for example, from Xia, Y. et al. etal. , Chem. Mater. (2002), 14, 4736-4745, Xia, Y. et al. etal. , Nano letters (2003) 3 (7), 955-960, can be mass-produced.

The transparent conductive layer can be formed by coating the polyimide film with a composition for forming a transparent conductive layer containing the metal nanowires. More specifically, a dispersion liquid (composition for forming a transparent conductive layer) in which the metal nanowires are dispersed in a solvent is applied onto the polyimide film, and then the coated layer is dried to form a transparent conductive layer. Can be formed.

Examples of the solvent include water, alcohol solvents, ketone solvents, ether solvents, hydrocarbon solvents, aromatic solvents and the like. From the viewpoint of reducing the environmental load, it is preferable to use water.

The dispersion concentration of the metal nanowires in the composition for forming a transparent conductive layer containing the metal nanowires is preferably in the range of 0.1 to 1% by mass. Within such a range, a transparent conductive layer having excellent conductivity and light transmission can be formed.

The composition for forming a transparent conductive layer containing the metal nanowires may further contain any suitable additive depending on the purpose. Examples of the additive include a corrosion inhibitor that prevents corrosion of metal nanowires, a surfactant that prevents aggregation of metal nanowires, and the like. The type, number and amount of additives used can be appropriately set according to the purpose. In addition, the composition for forming a transparent conductive layer may contain any suitable binder resin, if necessary.

Any suitable method can be adopted as a method for applying the composition for forming a transparent conductive layer containing the metal nanowires. Examples of the coating method include spray coating, bar coating, roll coating, die coating, inkjet coating, screen coating, dip coating, letterpress printing method, intaglio printing method, gravure printing method and the like.

As a method for drying the coating layer, any suitable drying method (for example, natural drying, blast drying, heat drying) can be adopted. For example, in the case of heat drying, the drying temperature is typically in the range of 100 to 200 ° C., and the drying time is typically 1 to 10 minutes.

When the transparent conductive layer contains metal nanowires, the thickness of the transparent conductive layer is preferably in the range of 0.01 to 10 μm, more preferably in the range of 0.05 to 3 μm, and particularly preferably in the range of 0. It is in the range of 1 to 1 μm. Within such a range, a transparent conductive film having excellent conductivity and light transmittance can be obtained.

When the transparent conductive layer contains metal nanowires, the total light transmittance of the transparent conductive layer is preferably 85% or more, more preferably 90% or more, still more preferably 95% or more.

(2) Metal mesh The transparent conductive layer containing the metal mesh is formed by forming fine metal wires in a grid pattern on a polyimide film. As the metal constituting the metal mesh, any suitable metal can be used as long as it is a highly conductive metal. Examples of the metal constituting the metal mesh include silver, gold, copper, nickel and the like. Further, a material obtained by plating (for example, gold plating) these metals may be used. Of these, copper is preferable, and migration phenomenon is unlikely to occur, and it is also preferable from the viewpoint of suppressing disconnection at the time of keystroke.

The transparent conductive layer containing the metal mesh can be formed by any suitable method. For the transparent conductive layer, for example, a photosensitive composition containing a silver salt (a composition for forming a transparent conductive layer) is applied onto a polyimide film, and then exposure treatment and development treatment are performed to form fine metal wires in a predetermined pattern. It can be obtained by doing. Further, the transparent conductive layer can also be obtained by printing a paste containing metal fine particles (composition for forming a transparent conductive layer) on a predetermined pattern.

Details of such a transparent conductive film and a method for forming the same are described in, for example, Japanese Patent Application Laid-Open No. 2012-18634. Further, as another example of the transparent conductive film composed of the metal mesh and the method for forming the transparent conductive film, the transparent conductive film described in JP-A-2003-331654 and the method for forming the transparent conductive film can be mentioned.

When the transparent conductive film contains a metal mesh, the thickness of the transparent conductive film is preferably in the range of 0.1 to 30 μm, more preferably in the range of 0.1 to 9 μm.

When the transparent conductive layer contains a metal mesh, the light transmittance of the transparent conductive layer is preferably 80% or more, more preferably 85% or more, still more preferably 90% or more.

(Touch panel)
The touch panel is configured to include the transparent conductive film.
In the touch panel, the pattern shape of the transparent conductive layer is not particularly limited as long as it is a pattern that operates well as a touch panel (for example, a capacitive touch panel). Examples thereof include the patterns described in Japanese Patent Application Laid-Open No. 2008-310550, Japanese Patent Application Laid-Open No. 2003-511799, and Japanese Patent Application Laid-Open No. 2010-541109.

As shown in FIG. 2, in the touch panel 7, the transparent conductive film 1 patterned on the x-axis and the transparent conductive film 1 patterned on the y-axis are laminated by using the adhesive film 5, and the adhesive film is formed on the outermost surface. It can be manufactured by providing the cover glass 6 via the 5, and the touch panel display device can be manufactured by combining the touch panel 7 with the liquid crystal display device 8.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

<< Synthesis of polyisoimide >>
Polyisoimide PI1 to PI42 were synthesized as follows.

<Synthesis of polyisoimide PI1>
A 1000 mL three-neck separable flask equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller and cooler was filled with 430 g of N, N-dimethylacetamide (DMAc) while passing nitrogen through the reactor. The temperature of B-7 was adjusted to 25 ° C., and 17.3 g (0.1 mol) of B-7 was dissolved as a diamine, and this solution was maintained at 25 ° C. After adding 29.4 g (0.1 mol) of A-2 as an acid anhydride, the mixture was stirred for 1 hour to dissolve and react. At this time, the temperature of the solution was maintained at 25 ° C. Further, the mixture was stirred for 12 hours to obtain a brown transparent and viscous polyamic acid solution having a solid content concentration of 15% by mass.

To this polyamic acid, triethylamine (TEA) was added in an amount twice the total molar amount of the acid anhydride used in the synthesis, and then the mixture was stirred at room temperature (25 ° C.) for 1 hour. Then, with stirring at 0 ° C., trifluoroacetic anhydride (TFAA) was added to the reaction solution in an amount twice as much as the total molar amount of the acid anhydride used in the synthesis over 1 hour, and then at room temperature (TFAA). The mixture was stirred at 25 ° C. for 24 hours.
After completion of the reaction, the resulting solution was poured into a large excess of acetone to precipitate the reaction product. The recovered precipitate was washed with acetone and then dried under reduced pressure at 40 ° C. for 15 hours to obtain polyisoimide PI1. The resulting solid polyisoimide PI1 from IR spectrum measurement, isoimide skeleton content _{(= S iso / (S iso} + S paa + S im)) was calculated as 0.96 (96mol%).
The weight average molecular weight of polyisoimide PI1 was 15,000.

In this example, the weight average molecular weight was measured by gel permeation chromatography (GPC). The measurement conditions are as shown below.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Use by connecting 3 pieces manufactured by Showa Denko KK)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Science)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 500 to 1000000 A calibration curve of 13 samples was used. 13 samples were used at approximately equal intervals.

<Synthesis of polyisoimide PI2 to PI37>
Polyisoimide PI2 to PI37 were synthesized as the same molar ratio and synthesis method as the synthesis of polyisoimide PI1 except that the acid anhydride and diamine used in the synthesis were changed as shown in Table 2.
The resulting solid polyisoimide PI2~PI37 from the measurement of IR spectrum, isoimide skeleton content _{(= S iso / (S iso} + S paa + S im)) was calculated with all 0.95 (95 mol%) or more.
The weight average molecular weights of the polyisoimides PI2 to PI37 are as shown in Table 2.

<Synthesis of polyisoimide PI38>
Similar to the synthesis of polyisoimide PI1 except that the amount of trifluoroacetic anhydride (TFAA) used in the synthesis of polyisoimide PI1 was changed to 1.8 times the total molar amount of acid anhydride used in the synthesis. Polyisoimide PI38 was synthesized as a molar ratio and synthesis method.
The resulting solid polyisoimide PI38 from the measurement of IR spectrum, isoimide skeleton content _{(= S iso / (S iso} + S paa + S im)) was calculated as 0.88 (88mol%).
The weight average molecular weight of polyisoimide PI38 was 30,000.

<Synthesis of polyisoimide PI39>
Similar to the synthesis of polyisoimide PI1 except that the amount of trifluoroacetic anhydride (TFAA) used in the synthesis of polyisoimide PI1 was changed to 1.5 times the total molar amount of acid anhydride used in the synthesis. Polyisoimide PI39 was synthesized as a molar ratio and synthesis method.
The resulting solid polyisoimide PI38 from the measurement of IR spectrum, isoimide skeleton content _{(= S iso / (S iso} + S paa + S im)) was calculated as 0.70 (70mol%).
The weight average molecular weight of polyisoimide PI39 was 40,000.

<Synthesis of polyisoimide PI40>
A 500 mL three-neck separable flask equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a cooler was filled with 275 g of N, N-dimethylacetamide (DMAc) while passing nitrogen through the reactor. The temperature of B-7 was adjusted to 25 ° C., 17.8 g (0.1 mol) of B-7 was dissolved as a diamine, and this solution was maintained at 25 ° C. After adding 31.0 g (0.1 mol) of A-7 as an acid anhydride, the mixture was stirred for 1 hour to dissolve and react. At this time, the temperature of the solution was maintained at 25 ° C. Further, the mixture was stirred for 12 hours to obtain a polyamic acid solution having a solid content concentration of 15% by mass.

Triethylamine (TEA) was added to the polyamic acid in an amount twice the total molar amount of the acid anhydride used in the synthesis, and then the mixture was stirred at room temperature (25 ° C.) for 1 hour. Then, with stirring at 0 ° C., trifluoroacetic anhydride (TFAA) was added to the reaction solution in an amount twice as much as the total molar amount of the acid anhydride used in the synthesis over 1 hour, and then at room temperature (TFAA). The mixture was stirred at 25 ° C. for 24 hours.
After completion of the reaction, the resulting solution was poured into a large excess of acetone to precipitate the reaction product. The recovered precipitate was washed with acetone and then dried under reduced pressure at 40 ° C. for 15 hours to obtain Polyisoimide PI40.
The resulting polyisoimide solids, from the measurement of IR spectrum, isoimide skeleton content _{(= S iso / (S iso} + S paa + S im)) was calculated as 0.96 (96mol%).
The weight average molecular weight of polyisoimide PI40 was 36000.

<Synthesis of polyisoimide PI41 and PI42>
Polyisoimide PI41 and PI42 were synthesized as the same molar ratio and synthesis method as the synthesis of polyisoimide PI38 except that the acid anhydride and diamine used in the synthesis were changed as shown in Table 2.

Obtained polyisoimide PI41 and PI42 solids, from the measurement of IR spectrum, isoimide skeleton content _{(= S iso / (S iso} + S paa + S im)) was calculated as both 0.95 (95 mol%) or more.
The weight average molecular weights of the polyisoimides PI41 and PI42 were 60,000 and 100,000, respectively.

In the synthesis of polyisoimide PI1 to PI42, when a plurality of dicarboxylic acid anhydrides are used, a plurality of types of dicarboxylic acid anhydrides are dissolved at the same time, and when a plurality of types of diamines are used, they are simultaneously dissolved in N, N-dimethylacetamide. After that, it was added dropwise to the reaction solution. The total amount of dicarboxylic acid and the total amount of diamine used were added so as to be the same molar amount as the material constituting polyisoimide PI1. When two types of dicarboxylic acid or diamine were used in combination, the mixing ratio of the two types of compounds was 1: 1 in an equimolar amount.

<solubility>
Polyimides PI1 to PI42, which were separately prepared in the same manner as above, were dissolved in γ-butyl lactone and heated at 200 ° C. to prepare polyimides.
Each of the produced polyimides was dissolved in 100 g (100% by mass) of dichloromethane and 100 g (100% by mass) of 1,3-dioxolane at 25 ° C., and the upper limit value (solubility) that could be dissolved in each solvent was measured. Classified by.
The results are shown in Table 2.

A: Solubility is greater than 7% by mass and 10% by mass or less B: Solubility is greater than 3% by mass and 7% by mass or less C: Solubility is greater than 0.01% by mass and 3% by mass or less D: Solubility is 10% by mass Greater than

<< Production of polyimide film >>
Polyimide films F1 to F74 were produced as follows.

<Preparation of polyimide film F1>
The polyisoimide PI1 was dissolved in dichloromethane so that the solid content concentration was 15% by mass, and the additive 1 as compound A was further added at a ratio of 10% by mass with respect to the polyisoimide PI1 to prepare a polyisoimide solution.

This solution was cast on a glass plate using a film applicator and dried under reduced pressure at 80 ° C. for 30 minutes. Then, the temperature was raised to 250 ° C. by 1 ° C. in 1 minute while maintaining the degree of reduced pressure, and then heating was performed under reduced pressure for 6 hours.
The oven was cooled and the film was peeled off from the stainless steel belt to obtain a polyimide film F1 having a thickness of 25 μm.
As a result of IR measurement of the obtained film, ^{the peak of 1820 cm -1 derived from the isoimide skeleton disappeared, and the peak of 1780 cm -1} indicating the imide skeleton was observed, confirming that the imidization proceeded completely. rice field. The imidization rate (imide skeleton content) was 0.95 (95 mol%), and the isoimide skeleton content was 0.03 (3 mol%).

<Preparation of polyimide films F2 to F61>
In the preparation of the polyimide film F1, the polyimide films F2 to F61 were produced in the same manner except that the polyisoimide and the compound A were changed as shown in Tables 3 and 4.
The imidization rate and the isoimide skeleton content were measured by the same method as for the polyimide film F1, and the imidization rates were all 0.95 (95 mol%) or more and the isoimide skeleton content was 0.03 (3 mol%) or less. I confirmed that there was.

<Preparation of polyimide films F62 and F63>
In the preparation of the polyimide film F1, the polyisoimide and the compound A were changed as shown in Table 4, and the polyimide film F62 was similarly heated at 250 ° C. for 2 hours and 30 minutes at the time of imidization after drying. And F63 were made.
The imidization rate and the isoimide skeleton content were measured by the same method as for the polyimide film F1, and the imidization rates of the polyimide films F62 and F63 were 0.88 (88 mol%), 0.80 (80 mol%), and the isoimide skeleton, respectively. It was confirmed that the contents were 0.08 (8 mol%) and 0.16 (16 mol%), respectively.

<Preparation of polyimide films F64 to F74>
In the preparation of the polyimide film F1, the polyimide films F64 to F74 were produced in the same manner except that the polyisoimide and the compound A were changed as shown in Table 4.
The imidization rate and the isoimide skeleton content were measured by the same method as for the polyimide film F1, and the imidization rates were all 0.95 (95 mol%) or more and the isoimide skeleton content was 0.03 (3 mol%) or less. I confirmed that there was.

<NICS value>
The NICS value of Compound A was calculated using Gaussian09 (Revision C.01, software manufactured by Gaussian, Inc., USA). Specifically, first, the structure was optimized using B3LYP (density functional theory) as the calculation method and 6-31G ^* (a function obtained by adding a polarization function to the split variance basis set) as the basis function. Then, using the optimized structure, a dummy atom is placed in the center of the ring for calculating the NICS value, and one point is calculated by the NMR shielding constant calculation method (GIAO) with ^{the basis function 6-311G ** to which the dispersion function is added.} The value obtained by multiplying the NMR shielding constant of the obtained dummy atom by -1 was taken as the NICS value of Compound A.

The NICS values in Tables 3 and 4 are the values of the ring having the largest NICS value among the aromatic rings in Compound A classified according to the following criteria. If this is not the case, it is set to D.

A: The value of the ring with the highest NICS value among aromatic rings is -14 or more and -10 or less. B: The value of the ring with the largest NICS value among aromatic rings is -15 or more and smaller than -14. Or greater than -10 and less than -7 C: The value of the ring with the largest NICS value among aromatic rings is less than -15 or greater than -7.

"evaluation"
The prepared polyimide films F1 to F74 were evaluated as follows.
The evaluation results are shown in Tables 3 and 4.

<Tension modulus>
For each of the produced polyimide films, a strip-shaped test piece having a flow direction (MD direction) and a width direction (TD direction) of 100 mm × 10 mm was cut out, and a tensile tester (Shimadzu Seisakusho “Autograph (R): Model” The average value of the tensile elastic modulus was calculated in each of the MD direction and the TD direction under the conditions of a tensile speed of 50 mm / min and a chuck distance of 40 mm using the name AG-5000A), and evaluated according to the following evaluation criteria. If it is the following classification A or B, there is no problem in practical use.

A: 7 GPa or more B: 3 GPa or more and less than 7 GPa C: less than 3 GPa

<Fold resistance>
Each of the produced polyimide films was subjected to a bending resistance test (sliding bending test) using a bending fatigue tester. Specifically, under the conditions of a load of 500 G, a refraction angle of 135 °, a refraction cycle of 175 cpm, and a radius of refraction locality of 0.38 mm, the bending is continued until the bent portion becomes cloudy visually, and the number of bends when the bent portion becomes cloudy is as follows. It was evaluated according to the evaluation criteria.
The polyimide film of the present invention was an excellent polyimide film in which white turbidity did not occur in the bent portion even when the number of times of bending was 6000 times or more, and curl generation after the bending test was small.

A: 10,000 times or more B: 6,000 times or more and less than 10,000 times C: Less than 6,000 times

<Total light transmittance>
For each of the produced polyimide films, one polyimide film sample whose humidity was adjusted for 24 hours in an air conditioning room at 23 ° C. and 55% RH was measured using a spectrophotometer U-3300 of Hitachi High-Technologies Co., Ltd. in accordance with JIS K 7375-2008. Then, the light transmittance (%) in the visible light region (range of 400 to 700 nm) was measured, the average value thereof was obtained, and the evaluation was performed according to the following evaluation criteria.

A: 80% or more B: 65% or more and less than 80% C: less than 65%

<Yellow index value (YI value)>
For each of the produced polyimide films, using the spectrophotometer U-3300 of Hitachi High-Technologies Corporation and the attached saturation calculation program, etc., the tristimulus values X and Y of the light source colors specified in JIS Z 8701. , Z was obtained, the yellow index value was obtained according to the definition of the following formula, and evaluation was performed according to the following evaluation criteria. If it is the following classification A or B, there is no problem in practical use.

Yellow index (YI) = 100 x (1.28X-1.06Z) / Y

A: Less than 2.0 B: 2.0 or more and less than 8.0 C: 8.0 or more

<summary>
As is clear from Tables 3 and 4, the polyimide film containing the polyimide resin composition of the present invention has all the tensile elastic modulus, folding resistance, total light transmittance and yellow index value as compared with the polyimide film of the comparative example. Was confirmed to be excellent in.
From the above, the polyimide having an aromatic moiety and the NICS value having a solubility in dichloromethane (100% by mass) or 1,3-dioxolane (100% by mass) at 25 ° C. in the range of 0.01 to 10% by mass are A polyimide resin composition containing compound A having a partial structure in the range of -15.0 to -7.0 and a molecular weight in the range of 250 to 10000 has mechanical properties (elasticity). , Folding resistance), a polyimide resin composition in which coloring peculiar to polyimide is suppressed, a method for producing the same, and a transparent substrate and a film for display containing the polyimide resin composition are useful. Understand.

1 Transparent conductive film 2 Polyimide film 3 Surface protective layer 4 Transparent conductive layer 5 Adhesive film 6 Cover glass 7 Touch panel 8 Liquid crystal display device

Claims (8)

A polyimide resin composition containing polyimide.
Table II of the specification (paragraph [0356]), wherein the solubility at 25 ° C. for dichloromethane (100% by weight) or 1,3-dioxolane (100% by weight) is in the range of 0.01 to 10% by weight. A polyimide prepared from any of the polyisoimides selected from PI1 to PI6, PI8 to PI18 and PI20 to PI39, which are A-2, A-7, A-8, A-11, A-13, A- B-2, B-7, B-11, B-12, B-14, which have an acid anhydride having a structure represented by 15, A-16 or A-19 and the following aromatic hydrocarbon ring group. A diamine having a structure represented by B-16, B-18, B-19, B-22, B-23, B-24, B-25 or B-26, and C- having the following aromatic heterocyclic group. 1. A diamine having a structure represented by C-3, C-7, C-8 or C-9, or D-3, D-7, D-8 or D having the following cyclic aliphatic hydrocarbon group. Polyimide made from polyisoimide made in combination with a diamine having a structure represented by -10, and
NICS value has a partial structure in the range of -15.0～-7.0, and a molecular weight from the following additive 1 additive 10 used as the compound A is in the range of 250 to 10,000 A polyimide resin composition comprising any of the additives of choice.

The polyimide resin composition according to claim 1, wherein the NICS value of the partial structure of the compound A is in the range of -14.0 to -10.0. The polyimide resin composition according to claim 1 or 2, wherein the polyimide has a partial structure represented by the following general formula (3) in an amount of 20 mol% or more.

(In the general formula (3), X ¹ is a single bond, an oxygen atom, a sulfur atom, an alkylene group, an amide group, a sulfonyl group, an amino group, a sulfide group, a carbonyl group, or a divalent linking group formed by a combination thereof. R ³ and R ⁴ each independently represent a hydrogen atom or a substituent, ^{and when there are a plurality of R 3} and R ⁴ , they may be the same or different. P and q. Represents an integer from 0 to 4, r represents an integer from 0 to 3. Where p or q represents an integer of 1 or more when ^{X 1 is a single coupling and p when r = 0.} Represents an integer greater than or equal to 1.) The polyimide has an isoimide partial structure represented by the following general formula (A1), a total amount of the imide partial structure represented by the following general formula (A2) and the amic acid partial structure represented by the following general formula (A3) ( The polyimide resin composition according to any one of claims 1 to 3, wherein the polyimide resin composition has a content in the range of 0.05 to 10 mol% with respect to 100 mol%).

(In the general formula (A1) ~ (A3), X 2 and ^{Y 2} each independently represent a substituted or unsubstituted tetravalent aromatic hydrocarbon ring group, aromatic heterocyclic group, the 4-39 carbon atoms Represents an acyclic aliphatic hydrocarbon group or a cyclic aliphatic hydrocarbon group having 4 to 39 carbon atoms, and represents a single bond, an oxygen atom, a sulfur atom, an alkylene group, an amide group, a sulfonyl group, an amino group, a sulfide group, and a carbonyl group. A plurality of aromatic hydrocarbon ring groups, aromatic heterocyclic groups, acyclic aliphatic hydrocarbon groups having 4 to 39 carbon atoms or 4 carbon atoms via a divalent linking group composed of a group or a combination thereof. ~ 39 cyclic aliphatic hydrocarbon groups may be linked. R ⁵ and R ⁶ each independently represent a hydrogen atom or a substituent, and when there are a plurality of ^{R 5} and R ^{6, they are the same.} It may be different or different.) A method for producing a polyimide resin composition containing polyimide.
Table II of the specification (paragraph [0356]), wherein the solubility at 25 ° C. for dichloromethane (100% by weight) or 1,3-dioxolane (100% by weight) is in the range of 0.01 to 10% by weight. A polyimide prepared from any of the polyisoimides selected from PI1 to PI6, PI8 to PI18 and PI20 to PI39, which are A-2, A-7, A-8, A-11, A-13 and A-. B-2, B-7, B-11, B-12, B-14, which have an acid anhydride having a structure represented by 15, A-16 or A-19 and the following aromatic hydrocarbon ring group. A diamine having a structure represented by B-16, B-18, B-19, B-22, B-23, B-24, B-25 or B-26, and C- having the following aromatic heterocyclic group. 1. A diamine having a structure represented by C-3, C-7, C-8 or C-9, or D-3, D-7, D-8 or D having the following cyclic aliphatic hydrocarbon group. A polyimide made of polyisoimide prepared in combination with a diamine having a structure represented by -10 has a partial structure having a NICS value in the range of -15.0 to -7.0, and has a partial structure. a step of molecular weight is added to any of the additives selected from the following additive 1 additive 10 used as compounds wherein a in the range of 250 to 10,000,
The step of rearranging the polyisoimide to form a polyimide and
A method for producing a polyimide resin composition.

The polyimide is the total amount of the isoimide partial structure represented by the following general formula (A1), the imide partial structure represented by the following general formula (A2), and the amic acid partial structure represented by the following general formula (A3). The method for producing a polyimide resin composition according to claim 5, wherein the polyimide resin composition has 90 mol% or more with respect to 100 mol%).

(In the general formula (A1) ~ (A3), X 2 and ^{Y 2} each independently represent a substituted or unsubstituted tetravalent aromatic hydrocarbon ring group, aromatic heterocyclic group, the 4-39 carbon atoms Represents an acyclic aliphatic hydrocarbon group or a cyclic aliphatic hydrocarbon group having 4 to 39 carbon atoms, and represents a single bond, an oxygen atom, a sulfur atom, an alkylene group, an amide group, a sulfonyl group, an amino group, a sulfide group, and a carbonyl group. A plurality of aromatic hydrocarbon ring groups, aromatic heterocyclic groups, acyclic aliphatic hydrocarbon groups having 4 to 39 carbon atoms or 4 carbon atoms via a divalent linking group composed of a group or a combination thereof. ~ 39 cyclic aliphatic hydrocarbon groups may be linked. R ⁵ and R ⁶ each independently represent a hydrogen atom or a substituent, and when there are a plurality of ^{R 5} and R ^{6, they are the same.} It may be different or different.) A transparent substrate containing the polyimide resin composition according to any one of claims 1 to 4. A display film containing the polyimide resin composition according to any one of claims 1 to 4.

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