WO2015083649A1

WO2015083649A1 - Method for producing polyimide, and polyimide obtained using such production method

Info

Publication number: WO2015083649A1
Application number: PCT/JP2014/081647
Authority: WO
Inventors: 利彦松本; 伸一小松
Original assignee: 学校法人東京工芸大学; Ｊｘ日鉱日石エネルギー株式会社
Priority date: 2013-12-05
Filing date: 2014-11-28
Publication date: 2015-06-11
Also published as: CN105829400A; JP2015108092A; TW201533096A; KR20160096123A

Abstract

Provided is a method for producing a polyimide, which obtains a polyimide having a repeating unit represented by general formula (2) [in the formula, R¹ and R² are synonymous with R¹ and R² in general formula (1)] by imidizing a poly(amic acid) having a repeating unit represented by general formula (1) [in the formula, R¹ denotes a specific group, and R² denotes a specific group] by using a mixture that contains this poly(amic acid), a halogen-based carboxylic acid anhydride and an aliphatic tertiary amine.

Description

Polyimide manufacturing method and polyimide obtained by the manufacturing method

The present invention relates to a polyimide production method and a polyimide obtained by the production method.

In recent years, mobile devices such as smartphones and tablet terminals have been actively developed, and market growth is expected. In the field of mobile devices such as smartphones and tablet terminals, there is a problem that a glass substrate used for a display or the like breaks due to an impact or a drop, and such a problem cannot be overlooked with the spread of mobile devices. . And in order to solve such a problem, measures such as manufacturing and using a glass substrate of a mobile device with glass that is harder to break, increasing the strength by making the glass substrate itself thicker, etc. have been studied. Yes. However, with these measures, the yield during processing of glass decreases, the weight of mobile devices increases due to the increase in thickness (decrease in portability), and the continuous operating time (driving time) due to the reduction in the battery occupied volume. Problems, such as shortening of the system, will occur. Under these circumstances, in the field of using glass substrates for mobile devices, etc., it has a high light transmission like glass and a sufficiently high heat resistance, and it is light and flexible like a resin film. The emergence of materials has been demanded.

Here, polyimide is known as a light and flexible material having high heat resistance. Among such polyimides, for example, aromatic polyimide (trade name “Kapton” manufactured by DuPont) has a high degree of heat resistance while having sufficient flexibility as a polymer material. It is also known as an indispensable material for advanced industries such as aviation. Such aromatic polyimide is synthesized by combining rigid and highly symmetric aromatic tetracarboxylic dianhydride and aromatic diamine, and is one of the highest class of heat resistance (glass transition) among polymer materials. Temperature (Tg): 410 ° C.) (see Engineering Plastics, Kyoritsu Shuppan, 1987, p88 (Non-patent Document 1)). However, such an aromatic polyimide has a brown color due to the occurrence of charge transfer (CT) between the aromatic ring-based tetracarboxylic dianhydride unit and the aromatic ring-based diamine unit. It could not be used for required glass replacement or optical applications. Therefore, the emergence of polyimide with sufficiently high heat resistance and sufficient light transmission that can be used for glass replacement applications, etc., is focused on the development of alicyclic polyimide that does not cause intramolecular CT. Has been.

As a method for producing such an alicyclic polyimide, generally, a polyamic acid is produced in a solvent by combining an alicyclic tetracarboxylic dianhydride and an aromatic diamine, and a polyamic acid ( After the polyamic acid) containing liquid (polyamic acid varnish) is obtained, the containing liquid is directly formed on a substrate or the like, dried, and then heated to a relatively high temperature {for example, the glass transition temperature as the heating temperature during imidization. It is common to employ the above high temperature (around 400 ° C.). } Is used to produce polyimide by heating and imidization (so-called thermal imidization method). However, alicyclic polyimides are structurally lower in decomposition temperature than aromatic polyimides and inferior in oxygen resistance, so high heating temperature causes coloring, and coloring is not possible in general alicyclic polyimide manufacturing methods. It was not always possible to produce a polyimide with sufficiently suppressed.

Also, as a method for producing an alicyclic polyimide, a chemical imidation method using a so-called imidizing agent can be employed. However, in such a chemical imidization method, from the viewpoint of heat resistance, when an alicyclic tetracarboxylic dianhydride having rigidity and good symmetry is used as a monomer, such alicyclic tetracarboxylic acid is used. Since acid dianhydride is low in solubility due to the molecular structure, usually, when a polyamic acid (polyamic acid) -containing liquid is obtained and an imidizing agent is added, the polyimide becomes uneven. There is a problem in that imidization proceeds due to precipitation and a non-uniform polyimide-containing liquid (polyimide varnish) is formed. Therefore, a system that can employ a chemical imidization method using a so-called imidizing agent in the production method of alicyclic polyimide is an acid dianhydride that is flexible and has lost symmetry as an alicyclic tetracarboxylic dianhydride. And the acid dianhydride and aromatic diamine are used in combination with a system having excellent solubility (for example, the latest revised polyimide: basics and applications, NTS Publishing, 2010, Chapter 4) , Polyimide film formation conditions and film properties, see p76 (Non-patent Document 2)). As described above, the conventional alicyclic polyimide obtained by adopting a general chemical imidation method is limited to a usable monomer and is not necessarily sufficient in terms of heat resistance. .

On the other hand, as an alicyclic polyimide having high light transmittance and heat resistance and a method for producing the same, in International Publication 2011/099518 (Patent Document 1), a repeating unit described by a specific general formula is used. The polyimide which has and its manufacturing method are disclosed. In the column of Examples described in Patent Document 1, a method of thermal imidization in which imidization is performed at a heating temperature of about 250 ° C. is employed. However, even in the manufacturing method described in Patent Document 1, a polyimide having sufficiently high light transmittance and sufficiently high heat resistance is efficiently and reliably manufactured by heating at a lower temperature. It was not always enough in terms.

International Publication 2011/099518 Pamphlet

The present invention has been made in view of the above-mentioned problems of the prior art, and it becomes possible to produce an alicyclic polyimide having sufficiently high heat resistance while utilizing a chemical imidization method, Polyimide with sufficient flexibility can be produced by low-temperature heating, and it is possible to more reliably prevent polyimide coloring during production. Adopting a low-temperature heating temperature and sufficiently high light transmittance It is an object of the present invention to provide a polyimide production method capable of producing a polyimide having sufficiently high heat resistance and sufficient flexibility more efficiently and reliably, and a polyimide obtained by the production method. .

As a result of intensive studies to achieve the above object, the present inventors first obtained the following knowledge. That is, in general polyimide production methods, as described above, polyamic acid (polyamic acid) is thermally dehydrated and cyclized to obtain polyimide, and an imidizing agent is added to polyamic acid (polyamic acid). However, there is a chemical imidation method in which dehydration and ring closure is chemically performed. The present inventors first studied using a chemical imidization method using a so-called imidizing agent from the viewpoint of producing polyimide by heating in a lower temperature range. However, when rigid and symmetric alicyclic tetracarboxylic dianhydrides are used as monomers in order to obtain heat resistance, conventional imidizing agents (for example, acetic anhydride, pyridine, etc.) can be used as they are. Even if an attempt is made to form polyimide, basically, precipitation of polyimide occurs in the solution, and imidization proceeds, resulting in a non-uniform polyimide-containing liquid (non-uniform polyimide varnish). For this reason, the types of imidizing agents used in the case of using rigid and symmetric alicyclic tetracarboxylic dianhydrides as monomers were further examined. For example, acetic anhydride generally used as an imidizing agent. In addition, in a system using pyridine, when an imidizing agent is added to a solution containing polyamic acid (polyamic acid-containing solution), polyimide may be precipitated in some cases, resulting in a non-uniform solution or a uniform solution. (In this case, polyamic acid and polyimide may coexist in such a solution.) In order to obtain sufficient imidization, heating at a relatively high temperature is required and a relatively low temperature is obtained. In the present invention, polyimide having sufficient flexibility cannot be obtained under the above heating conditions, and the resulting polyimide is very brittle. Luo was heading. When the polyamic acid-containing liquid is a non-uniform solution, it is difficult to apply it to obtain a uniform colorless transparent film. On the other hand, the polyamic acid-containing liquid (polyimide) after addition of the imidizing agent is difficult. Even when a partly contained solution becomes a uniform solution, it is difficult to obtain a film having sufficient flexibility by a casting method or the like by low-temperature heating, and industrial use of the resulting polyimide From the point of view, it is not always sufficient. Thus, from the viewpoint of the heat resistance of polyimide, when a rigid and symmetric alicyclic tetracarboxylic dianhydride is used as a monomer, even if a so-called imidizing agent is simply used, the polyimide is deposited. It is basically difficult to obtain a more uniform colorless and transparent film, and even if the polyamic acid-containing liquid (containing a part of the polyimide) after the addition of the imidizing agent becomes a uniform solution, the heating step In order to produce a polyimide having sufficient flexibility by imidizing by heating, it was found that heating at a relatively high temperature (for example, about 300 ° C. or more) is required in the heating step. And when such high temperature heating is performed, coloring of polyimide cannot necessarily be prevented sufficiently due to the heating temperature. Thus, in the case where a rigid and symmetric alicyclic tetracarboxylic dianhydride is used as a monomer, when a conventional imidizing agent is simply used, for example, a polyamic acid-containing liquid after addition of the imidizing agent Even if the solution (which contains a part of the polyimide) becomes a uniform solution, it is heated at a relatively low temperature (depending on the monomer, but for example, about 300 ° C. or less (more preferably about 250 ° C. or less, more preferably Under the heating conditions (about 200 ° C. or less), imidization does not always proceed sufficiently, and the resulting polyimide tends to be brittle and inflexible, and desired characteristics (sufficient flexibility, sufficient It has been found that it is not always possible to produce a polyimide having a high light transmittance and a sufficiently high heat resistance.

In addition, in order to obtain an alicyclic polyimide having high heat resistance, when using only a thermal imidization method without using an imidizing agent, the heating temperature is, for example, less than 200 ° C. although it varies depending on the monomer. When a low temperature is used, an equilibrium reaction in which the polyamic acid is decomposed into an acid dianhydride and an amine tends to be more advantageous than a reaction in which the polyamic acid (polyamic acid) is dehydrated and cyclized into a polyimide. Therefore, when only the thermal imidization method is used, it is necessary to perform a relatively high-temperature heating step as in the conventional method in order to more reliably produce a highly transparent and heat-resistant polyimide.

Based on such knowledge, the present inventors have further conducted extensive research. As a result, polyamic acid having a repeating unit represented by the following general formula (1), halogenated carboxylic acid anhydride, fat Surprisingly, by imidizing the polyamic acid using a mixture containing an aliphatic tertiary amine, an alicyclic polyimide having a sufficiently high heat resistance while utilizing a chemical imidization method It is possible to manufacture polyimide with sufficient flexibility by heating at a relatively low temperature, and it is possible to more reliably prevent polyimide coloring during manufacturing, and a lower heating temperature is adopted. And found that a polyimide having sufficiently high light transmittance, sufficiently high heat resistance, and sufficient flexibility can be produced more efficiently and reliably, and the present invention is completed. It led to.

That is, the method for producing the polyimide of the present invention has the following general formula (1):

[In the formula (1), R ¹ represents the following general formulas (I-1) to (I-10):

R ² represents a group selected from the group of tetravalent substituents represented by the following general formulas (II-1) to (II-4):

(In the formula, each R ³ independently represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluorine atom, and Q represents the formula: —O—, —S—, —CO—, —CONH—, —SO ₂ —, —C (CF ₃ ) ₂ —, —C (CH ₃ ) ₂ —, —CH ₂ —, —O—C ₆ H ₄ —C (CH ₃ ) ₂ —C ₆ H ₄ —O—, —O—C ₆ H ₄ —SO ₂ —C ₆ H ₄ —O—, —C (CH ₃ ) ₂ —C ₆ H ₄ —C (CH ₃ ) ₂ —, — This represents one selected from the group consisting of O—C ₆ H ₄ —C ₆ H ₄ —O— and —O—C ₆ H ₄ —O—.)
A group selected from the group of divalent substituents represented by the formula: ]
When the polyamic acid is imidized using a mixture containing a polyamic acid having a repeating unit represented by formula (II), a halogen-based carboxylic acid anhydride, and an aliphatic tertiary amine, the following general formula (2 ):

[In the formula (2), ^{R 1} and ^{R 2} are the same meanings as ^{R 1} and ^{R 2} in the general formula (1). ]
It is the method of obtaining the polyimide which has a repeating unit represented by these.

In the polyimide production method of the present invention, it is preferable that the step of imidizing the polyamic acid includes a step of heating the mixture at a temperature 80 to 300 ° C. lower than the glass transition temperature of the polyimide.

In the polyimide production method of the present invention, the content of the halogen-based carboxylic acid anhydride in the mixture is 0.01 to 4.0 mol with respect to 1 mol of the polyamic acid repeating unit. It is preferable.

Further, in the polyimide production method of the present invention, the content of the aliphatic tertiary amine in the mixture is 0.01 to 4.0 mol with respect to 1 mol of the repeating unit of the polyamic acid. It is preferable.

Further, in the polyimide production method of the present invention, the following general formula (3):

[In Formula (3), ^{R 1} has the same meaning as ^{R 1} in the general formula (1). ]
A tetracarboxylic dianhydride represented by the following general formula (4):

Wherein (4), ^{R 2} has the same meaning as ^{R 2} in the general formula (1). ]
It is preferable to further include a step of obtaining the polyamic acid by reacting with an aromatic diamine represented by the formula:

In the polyimide production method of the present invention, the halogen-based carboxylic acid anhydride is trifluoroacetic anhydride, difluoroacetic anhydride, fluoroacetic anhydride, pentafluoropropionic anhydride, heptafluorobutyric anhydride, trichloroacetic anhydride, Dichloroacetic anhydride, chloroacetic anhydride, tribromoacetic anhydride, dibromoacetic anhydride, bromoacetic anhydride, chlorodifluoroacetic anhydride, chlorotetrafluoropropionic anhydride, chlorohexafluorobutyric anhydride and a mixed acid anhydride forming these anhydrides At least one selected from the group consisting of trifluoroacetic anhydride, pentafluoropropionic anhydride, heptafluorobutyric anhydride and a mixed acid anhydride of these anhydrides. It should be at least one Preferred.

Further, in the above-described polyimide production method of the present invention, the aliphatic tertiary amine is represented by the following general formula (5):

[In Formula (5), each R ³ independently represents an alkyl group having 1 to 10 carbon atoms. ]
It is preferable that it is the tertiary amine represented by these.

The polyimide of the present invention is a polyimide obtained by the above-described method for producing a polyimide of the present invention.

According to the present invention, it is possible to produce an alicyclic polyimide having sufficiently high heat resistance while utilizing a chemical imidization method, and producing a polyimide having sufficient flexibility by heating at a relatively low temperature. It is possible to prevent the coloring of polyimide at the time of manufacture more reliably and adopt a lower heating temperature to have sufficiently high light transmittance, sufficiently high heat resistance and sufficient flexibility It becomes possible to provide a polyimide production method that makes it possible to produce polyimide more efficiently and reliably, and a polyimide obtained by the production method.

2 is a graph showing an IR spectrum of components (reprecipitate) in the mixture obtained in Example 1. FIG. 2 is a graph showing a ¹ H-NMR spectrum of a component (reprecipitate) in a mixture obtained in Example 1. FIG. 3 is an enlarged graph of the vicinity of 6 ppm to 13 ppm in the ¹ H-NMR spectrum shown in FIG. 2 is a graph showing an IR spectrum of the polyimide (film) obtained in Example 1. FIG. 1 is a graph showing a ¹ H-NMR spectrum of a polyimide (film) obtained in Example 1. 6 is an enlarged graph of the vicinity of 6 ppm to 13 ppm of the ¹ H-NMR spectrum shown in FIG. 3 is a graph showing an IR spectrum of components (reprecipitate) in the mixture obtained in Example 2. FIG. 2 is a graph showing a ¹ H-NMR spectrum of a component (reprecipitate) in a mixture obtained in Example 2. FIG. FIG. 9 is an enlarged graph of the vicinity of 6 ppm to 13 ppm of the ¹ H-NMR spectrum shown in FIG. 3 is a graph showing an IR spectrum of a polyimide (film) obtained in Example 2. FIG. 2 is a graph showing a ¹ H-NMR spectrum of a polyimide (film) obtained in Example 2. FIG. 12 is an enlarged graph of the vicinity of 6 ppm to 13 ppm of the ¹ H-NMR spectrum shown in FIG.

Hereinafter, the present invention will be described in detail on the basis of preferred embodiments thereof.

[Production method of polyimide]
The manufacturing method of the polyimide of this invention is demonstrated. As described above, the method for producing a polyimide of the present invention contains a polyamic acid having a repeating unit represented by the general formula (1), a halogen-based carboxylic acid anhydride, and an aliphatic tertiary amine. This is a method of obtaining a polyimide having a repeating unit represented by the general formula (2) by imidizing the polyamic acid using a mixture.

In addition, with such a method for producing a polyimide according to the present invention, desired characteristics (sufficient flexibility, sufficiently high light transmittance, and sufficiently high heat resistance can be obtained even when heating at a lower temperature range during production. The reason why it is possible to efficiently produce a polyimide having) is not necessarily clear, but the present inventors speculate as follows. That is, in the present invention, first, the halogen-based carboxylic acid anhydride and the aliphatic tertiary amine are used in combination. Thus, by utilizing the halogenated carboxylic acid anhydride and the aliphatic tertiary amine in combination, the halogenated carboxylic acid anhydride functions as a dehydrating agent in the mixture, and the aliphatic A tertiary amine functions as a dehydration accelerator, and partial imidization of the polyamic acid (polyamic acid) proceeds. Even when such partial imidization proceeds, when the mixture contains a solvent, the polyimide to be formed is soluble in the solvent used for the polymerization reaction. Does not occur and a uniform mixture is obtained. When such a uniform mixture is heated under low temperature conditions, the halogen-based carboxylic acid anhydride and the aliphatic tertiary amine in the mixture function catalytically, and in the mixture The imidization of the polyamic acid proceeds efficiently, and a polyimide having desired properties (sufficient flexibility, sufficiently high light transmittance, and sufficiently high heat resistance) can be produced. Here, the case of forming a film-like polyimide is taken as an example, and the production of the polyimide will be briefly described. As described above, a uniform mixture in which the polyamic acid (polyamic acid) is partially imidized is obtained. Then, the mixture can be cast uniformly (cast film formation). And when the coating film after such cast film formation is dried, a film (dry coating film) made of a mixture of uniform polyamic acid (polyamic acid) and polyimide having sufficiently high light transmittance is produced. Is possible. In such a dry coating film, the halogenated carboxylic acid anhydride and the aliphatic tertiary amine remaining in the coating film function like a catalyst, so that imidization occurs even when heated at a low temperature. It will be possible to proceed sufficiently. As described above, in the present invention, a polyimide having desired characteristics (sufficient flexibility, sufficiently high light transmittance and sufficiently high heat resistance) can be produced by a sufficiently simple method and a low-temperature heating step. . As described above, in the present invention, partial imidization by the chemical imidization method that occurs in the mixture and subsequent imidization by the combined heat and chemical method by heating can be used, so that lower temperature heating is possible. Thus, polyimide can be produced efficiently. And in this invention, since it becomes possible to manufacture a polyimide by a lower temperature heating at the time of manufacture, it can also manufacture a polyimide by a simpler process and using a simpler manufacturing equipment. . Therefore, it can be said that the method for producing the polyimide of the present invention is an excellent method from the viewpoints of industrialization and cost reduction (economic efficiency). Further, by producing polyimide using the mixture, it is not always necessary to perform a heating step at a relatively high temperature (for example, higher than 300 ° C.) that causes coloring (the conventional thermal imidization method is not required). Therefore, coloring of the resulting polyimide can be prevented more sufficiently and more reliably. Therefore, when using the said mixture, the polyimide film which has sufficiently high light transmittance can be manufactured efficiently. From this point of view, the polyimide production method of the present invention can provide the desired characteristics (sufficient flexibility, sufficiently high light transmittance and sufficient even when heating in a lower temperature range during production. The present inventors speculate that it is possible to efficiently produce a polyimide having high heat resistance.

Hereinafter, first, each component used in the present invention will be described.

(Polyamide acid)
The polyamic acid according to the present invention will be described. Such polyamic acid has the following general formula (1):

It is represented by

In such general formula (1), R ¹ represents the following general formulas (I-1) to (I-10):

Is a group selected from the group of tetravalent substituents represented by the formula: As such R ¹ , from the viewpoints of heat resistance, transparency, linear expansion coefficient, and strength, the above-mentioned general formulas (I-1), (I-3), (I-9) and (I-10) A group selected from the above is preferable, and a group selected from the above general formulas (I-9) and (I-10) is more preferable.

In the general formula (1), R ² represents the following general formulas (II-1) to (II-4):

Is a group selected from the group of divalent substituents represented by the formula:

In such general formula (II-3), each R ³ is independently one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms and a fluorine atom. As such R ³ , from the viewpoint of heat resistance, a hydrogen atom, a fluorine atom, a methyl group or an ethyl group is more preferable, and a hydrogen atom is particularly preferable.

In the general formula (II-4), Q is a group represented by the formula: —O—, —S—, —CO—, —CONH—, —SO ₂ —, —C (CF ₃ ) ₂ —, —C ( CH ₃ ) ₂ —, —CH ₂ —, —O—C ₆ H ₄ —C (CH ₃ ) ₂ —C ₆ H ₄ —O—, —O—C ₆ H ₄ —SO ₂ —C ₆ H ₄ — _{_{_{_{O -, - C (CH 3}}}} ) 2 -C 6 H 4 -C (CH 3) 2 -, - O-C 6 H 4 -C 6 H 4 -O- and _{_-O-C} 6 H 4 -O- It is 1 type selected from the group which consists of group represented by these. As such Q, from the viewpoint of balance between heat resistance and solubility, the formula: —O—C ₆ H ₄ —O—, —O—, —C (CH ₃ ) ₂ —, —CH ₂ —, or A group represented by —O—C ₆ H ₄ —C (CH ₃ ) ₂ —C ₆ H ₄ —O— is preferred, represented by the formula: —O—C ₆ H ₄ —O— or —O—. Are particularly preferred.

Further, the groups represented by the general formulas (II-1) to (II-4) that can be selected as R ² in the general formula (1) can have a sufficiently high glass transition temperature. In addition, from the viewpoint that the linear expansion coefficient can be made sufficiently low, the balance of these characteristics is improved, and higher heat resistance can be obtained, the general formula (II-3) or (II-4) It is more preferable that it is group represented by these.

Furthermore, among R ^2, the group represented by the general formula (II-3) or the general formula (II) can be used from the viewpoint that the linear expansion coefficient can be made lower and higher heat resistance can be obtained. II-4) and the group Q is represented by —CONH—, —COO—, —CO—, —C ₆ H ₄ — (more preferably a group represented by —CONH— or —COO—). And particularly preferably a group that is at least one of the groups represented by —CONH—.

In addition, as R ² , from the viewpoint that a higher degree of flexibility (flexibility) can be imparted to the obtained polyimide, the group represented by the general formula (II-1) or the general formula ( II-4) and Q is at least one group selected from —O—, —S—, —CH ₂ —, —O—C ₆ H ₄ —O— (more preferably — It is preferably a group that is one of the groups represented by O— and —CH ₂ —, more preferably a group represented by —O—.

As the polyamic acid, from the viewpoint that a sufficiently high glass transition temperature, a sufficiently low linear expansion coefficient, and sufficient flexibility (flexibility) can be imparted to the obtained polyimide in a balanced manner at a higher level. It is preferable to contain a plurality of (two or more) repeating units represented by the general formula (1) having different types of R ² .

The polyamic acid having a repeating unit represented by the general formula (1) preferably has an intrinsic viscosity [η] of 0.05 to 3.0 dL / g, and preferably 0.2 to 2.0 dL / g. g is more preferable, and 0.4 to 1.5 dL / g is still more preferable. When the intrinsic viscosity [η] is smaller than 0.05 dL / g, when a film-like polyimide is produced using the intrinsic viscosity [η], the resulting film tends to be brittle, while 3.0 dL / g is reduced. If it exceeds, the viscosity is too high and the processability is lowered, and for example, when a film is produced, it tends to be difficult to obtain a uniform film. Such intrinsic viscosity [η] can be measured as follows. Specifically, first, a measurement sample (solution) in which N, N-dimethylacetamide is used as a solvent and the polyamic acid is dissolved in the N, N-dimethylacetamide so as to have a concentration of 0.5 g / dL. obtain. Next, using the measurement sample, the viscosity of the measurement sample is measured using a kinematic viscometer under a temperature condition of 30 ° C. (for example, as a temperature condition of 30 ° C. using a thermostatic bath of 30 ° C.). The obtained value is adopted as the intrinsic viscosity [η]. In addition, as such a kinematic viscometer, an automatic viscosity measuring device (trade name “VMC-252”) manufactured by Koiso Co., Ltd. is used.

Moreover, the process for producing such a polyamic acid is not particularly limited, and a process capable of producing a polyamic acid having a repeating unit represented by the general formula (1) can be appropriately employed. However, among these, in the organic solvent, the following general formula (3):

Wherein (4), ^{R 2} has the same meaning as ^{R 2} in the general formula (1). ]
It is preferable to employ a step of obtaining the polyamic acid by reacting with an aromatic diamine represented by the formula: That is, in the method for producing a polyimide of the present invention, the tetracarboxylic dianhydride represented by the general formula (3) is reacted with the aromatic diamine represented by the general formula (4). It is preferable to further include a step of obtaining a polyamic acid.

The tetracarboxylic dianhydride used in the step of obtaining such polyamic acid is represented by the above general formula (3), and R ¹ in the general formula (3) is the above general formula (1). R ¹ synonymous in (formula (3) suitable for R ¹ in are also the same as the R ¹ of the general formula (1).)
Examples of the tetracarboxylic dianhydride represented by the general formula (3) include norbornane-2-spiro-α-cyclopentanone-α′-spiro-2 ″ -norbornane-5,5 ′. ', 6,6''-tetracarboxylic dianhydride, norbornane-2-spiro-α-cyclohexanone-α'-spiro-2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic Acid dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic acid Dianhydride, 1,2,3,4-cyclohexanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarboxynorbornane-2-acetic acid dianhydride 2,3,4,5-tetrahydrofuran Lacarboxylic dianhydride, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3 -Dione, 1,3,3a, 4,5,9b-hexahydro-5-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1, 3-dione, 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1 , 3-dione, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, bicyclo [2,2,2] -oct-7-ene -2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3 ', 4,4'-tetracar Boronic acid dianhydride, bicyclo [2,2,1] -heptane-2,3,5,6-tetracarboxylic dianhydride, decahydrodimethanonaphthalene-2,3,6,7-tetracarboxylic acid dianhydride Anhydrides, dodecahydro-1,4: 5,8-dimethanoanthracene-9,10-dione-2,3: 6,7-tetracarboxylic dianhydride and the like.

Further, the production method of such tetracarboxylic dianhydride is not particularly limited, and a known method can be appropriately employed. For example, the method described in International Publication No. 2011/099518 is appropriately used. It may be adopted. Moreover, you may utilize a commercially available thing as such a tetracarboxylic dianhydride.

The aromatic diamine used in the step of obtaining the polyamic acid is represented by the general formula (4), and R ² in the general formula (4) is R in the general formula (1). ² synonymous (formula (4) suitable for R ² in also is the same as R ² in the general formula (1).)
Examples of the aromatic diamine represented by the general formula (4) include 4,4′-diaminodiphenylmethane, 4,4 ″ -diamino-p-terphenyl, 3,3′-diaminodiphenylmethane, 4 , 4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 2 , 2-bis (4-aminophenoxyphenyl) propane, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl ] Sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2′-bis (trifluoromethyl) -4,4 ′ -Diaminobiphenyl, 3,4'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 9,9-bis (4-aminophenyl) fluorene, p-diaminobenzene (alias: p- Phenylenediamine), m-diaminobenzene, o-diaminobenzene, 4,4′-diaminobiphenyl, 3,3′-diaminobiphenyl, 2,2′-diaminobiphenyl, 3,4′-diaminobiphenyl, 2,6- Diaminonaphthalene, 1,4-diaminonaphthalene, 1,5-diaminonaphthalene, 4,4 ′-[1,3-phenylenebis (1-methyl-ethylidene)] bisaniline, 4,4 ′-[1,4-phenylene Bis (1-methyl-ethylidene)] bisaniline, 2,2′-dimethyl-4,4′-diaminobiphenyl : O-tolidine), 3,3′-dimethyl-4,4′-diaminobiphenyl, 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfide, 4-bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-diaminobenzanilide, 4,4'-diaminophenylbenzoate (also known as 4,4'-) Diaminodiphenyl ester), 9,9′-bis (4-aminophenyl) fluorene, o-tolidine sulfone, 1,3′-bis (4-aminophenoxy) -2,2-dimethylpropane, 2,3,5, 6-tetramethyl-1,4-phenylenediamine, 3,3 ′, 5,5′-tetramethylbenzidine, 1,5-bis (4-aminophenoxy) pentane Diethyl toluene diamine, amino benzylamine, bisaniline M, bisaniline P, and the like.

Further, the method for producing such an aromatic diamine is not particularly limited, and a known method can be appropriately employed. Moreover, you may use a commercially available thing suitably as such aromatic diamine.

Furthermore, as an organic solvent used in the step of obtaining the polyamic acid, both a tetracarboxylic dianhydride represented by the general formula (3) and an aromatic diamine represented by the general formula (4) are used. An organic solvent that can be dissolved is preferable. Examples of such organic solvents include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, propylene carbonate, tetramethylurea, 1,3- Aprotic polar solvents such as dimethyl-2-imidazolidinone, hexamethylphosphoric triamide, pyridine; phenol solvents such as m-cresol, xylenol, phenol, halogenated phenol; tetrahydrofuran, dioxane, cellosolve, glyme And ether solvents such as benzene, toluene, xylene, 2-chloro-4-hydroxytoluene, and the like. Such organic solvents may be used singly or in combination of two or more.

Moreover, in the process of obtaining the said polyamic acid, the usage-amount in particular of the tetracarboxylic dianhydride represented by the said General formula (3) and the aromatic diamine represented by the said General formula (4) is not restrict | limited. However, their molar ratio ([tetracarboxylic dianhydride]: [aromatic diamine]) is 0.5: 1.0 to 1.0: 0.5 (more preferably 0.9: 1.0 to 1.0: 0.9) is preferable. If the amount of tetracarboxylic dianhydride used is less than the lower limit, the yield tends to decrease. On the other hand, even if the amount exceeds the upper limit, the yield tends to decrease.

In the step of obtaining the polyamic acid, the proportion of the tetracarboxylic dianhydride represented by the general formula (3) and the aromatic diamine represented by the general formula (4) The acid anhydride group of the tetracarboxylic dianhydride represented by the general formula (3) is 0.2 to 2 equivalents relative to 1 equivalent of the amino group of the aromatic diamine represented by the formula (4). It is preferable to use 0.3 to 1.2 equivalents. When such a use ratio is less than the lower limit, the polymerization reaction does not proceed efficiently, and a high molecular weight polyamic acid tends not to be obtained. On the other hand, when the upper limit is exceeded, a high molecular weight polyamic acid is obtained as described above. It tends to be impossible.

Furthermore, as the usage-amount of the said organic solvent in the process of obtaining the said polyamic acid, the total amount of the aromatic diamine represented by the tetracarboxylic dianhydride represented by the said General formula (3) and the said General formula (4) However, the amount is preferably 0.1 to 50% by mass (more preferably 10 to 30% by mass) with respect to the total amount of the reaction solution. If the amount of the organic solvent used is less than the lower limit, the polyamic acid tends not to be obtained efficiently. On the other hand, if it exceeds the upper limit, stirring tends to be difficult due to the increase in viscosity.

In the step of obtaining the polyamic acid, when the tetracarboxylic dianhydride represented by the general formula (3) is reacted with the aromatic diamine represented by the general formula (4), a reaction rate is obtained. From the viewpoint of improving and obtaining a polyamic acid having a high degree of polymerization, a base compound may be further added to the organic solvent. Examples of such basic compounds include, but are not limited to, triethylamine, tributylamine, trihexylamine, 1,8-diazabicyclo [5.4.0] -undecene-7, pyridine, isoquinoline, N-methylpiperidine, α-picoline and the like can be mentioned. The amount of such a base compound used is preferably 0.001 to 10 equivalents relative to 1 equivalent of the tetracarboxylic dianhydride represented by the general formula (6), More preferably, it is 0.1 equivalent. If the amount of such a basic compound used is less than the lower limit, the effect of addition tends to be lost. On the other hand, if it exceeds the upper limit, it tends to cause coloring or the like.

In the step of obtaining the polyamic acid, the reaction temperature when the tetracarboxylic dianhydride represented by the general formula (3) and the aromatic diamine represented by the general formula (4) are reacted is as follows: The temperature may be appropriately adjusted to a temperature at which these compounds can be reacted, and is not particularly limited, but is preferably 80 ° C. or less, and preferably −30 to 30 ° C. Moreover, as a method of reacting the tetracarboxylic dianhydride represented by the above general formula (3) and the aromatic diamine represented by the above general formula (4) that can be employed in the step of obtaining such a polyamic acid. Can appropriately utilize a known method capable of performing a polymerization reaction of tetracarboxylic dianhydride and aromatic diamine. For example, the tetracarboxylic dianhydride represented by the above general formula (3) at the reaction temperature after dissolving the aromatic diamine in a solvent under an inert atmosphere such as nitrogen, helium or argon at atmospheric pressure A method may be employed in which a product is added and then reacted for 10 to 48 hours. If the reaction temperature or reaction time is less than the lower limit, it tends to be difficult to cause sufficient reaction. On the other hand, if the upper limit is exceeded, the probability of mixing a substance (such as water vapor) that degrades the polymer increases and the molecular weight increases. It tends to decrease.

In this way, by reacting the tetracarboxylic dianhydride represented by the above general formula (3) with the aromatic diamine represented by the above general formula (4), it is represented by the above general formula (1). Thus, a polyamic acid having at least one repeating unit can be obtained. Further, the polyamic acid having the repeating unit represented by the above general formula (1) thus obtained may be isolated and used as a component for forming the mixture according to the present invention. Alternatively, without isolating the polyamic acid having the repeating unit represented by the general formula (1), the tetracarboxylic dianhydride represented by the general formula (3) and the general formula (3) in an organic solvent can be used. 4) The reaction solution obtained by reacting with the aromatic diamine represented by 4) (the reaction solution containing the polyamic acid having the repeating unit represented by the general formula (1)) is used as it is. You may utilize as a component for forming the mixture concerning this invention in the state which exists in a liquid. In addition, when isolating and using the polyamic acid which has a repeating unit represented by the said General formula (1) from the said reaction liquid, it does not restrict | limit especially as an isolation method, It is possible to isolate a polyamic acid. Such known methods can be employed as appropriate, and for example, a method of isolating as a reprecipitate may be employed.

(Halogen carboxylic anhydride)
The halogen-based carboxylic acid anhydride according to the present invention will be described. In the present invention, in order to produce a polyimide having sufficient flexibility by heating at a relatively low temperature, moderate reactivity (condensability) is exhibited during chemical imidization, and heating at a relatively low temperature (during curing) From the standpoint of obtaining imide ring-closing activity, a halogen-based carboxylic acid anhydride is used in combination with an aliphatic tertiary amine. Even when such compounds other than halogen-based carboxylic acid anhydrides are combined with aliphatic tertiary amines, they do not exhibit appropriate reactivity (condensation) during chemical imidization, and exhibit imide ring-closing activity when heated at relatively low temperatures. It is not possible to obtain a polyimide that is sufficiently flexible and highly light transmissive.

Here, the halogen-based carboxylic acid anhydride is a compound in which a carboxylic acid anhydride group and an aliphatic group containing at least one halogen atom are bonded {halogen-substituted aliphatic group (at least one hydrogen atom is a halogen atom). A compound in which an aliphatic group substituted with a carboxylic acid anhydride group is bonded}. As described above, the halogen-based carboxylic acid anhydride according to the present invention includes an aliphatic group in which at least one hydrogen atom is substituted with a halogen atom (from the viewpoint of moderate reactivity, moderate imide ring-closing activity, and volatility). A compound in which a halogen atom-substituted aliphatic group) and a carboxylic acid anhydride group are bonded is used.

In addition, the halogen atom contained in such a halogen-based carboxylic acid anhydride is preferably a fluorine atom, a chloro atom, or a bromo atom from the viewpoint of moderate reactivity, moderate imide ring-closing activity, and volatility. An atom and a chloro atom are more preferable, and a fluorine atom is particularly preferable. In addition, the aliphatic group in the halogen atom-substituted aliphatic group is preferably a linear alkyl group having 1 to 5 carbon atoms or a branched alkyl group having 3 to 5 carbon atoms. A linear alkyl group of ˜3 is more preferred.

Among such halogen-based carboxylic acid anhydrides, from the viewpoint of moderate reactivity, moderate imide ring-closing activity, and volatility, trifluoroacetic anhydride, difluoroacetic anhydride, fluoroacetic anhydride, pentafluoropropionic anhydride, Heptafluorobutyric anhydride, trichloroacetic anhydride, dichloroacetic anhydride, chloroacetic anhydride, tribromoacetic anhydride, dibromoacetic anhydride, bromoacetic anhydride, chlorodifluoroacetic anhydride, chlorotetrafluoropropionic anhydride, chlorohexafluorobutyric anhydride, and these Forming acids (trifluoroacetic acid, difluoroacetic acid, fluoroacetic acid, pentafluoropropionic acid, heptaful) that form anhydrides (trifluoroacetic anhydride, difluoroacetic anhydride, fluoroacetic anhydride, pentafluoropropionic anhydride, heptafluorobutyric anhydride, etc.) At least one selected from mixed acid anhydrides of robutyric acid and the like, and trifluoroacetic anhydride, pentafluoropropionic anhydride, heptafluorobutyric anhydride, and mixed acid anhydrides of these acids forming these anhydrides More preferably, at least one selected from the group consisting of trifluoroacetic anhydride, pentafluoropropionic anhydride, and a mixed acid anhydride of acids forming these anhydrides is more preferable. The “mixed acid anhydride” here refers to an acid anhydride obtained by dehydration condensation of two types of halogen-based carboxylic acids. Furthermore, among these halogen-based carboxylic anhydrides, trifluoroacetic anhydride, pentafluoropropionic anhydride, and heptafluorobutyric anhydride are more preferable, and trifluoroacetic anhydride and pentafluoropropionic anhydride are particularly preferable. In addition, such a halogen-type carboxylic anhydride may be used individually by 1 type, or may be used in combination of 2 or more type.

The method for producing such a halogen-based carboxylic acid anhydride is not particularly limited, and a known method can be appropriately employed. Moreover, as such a halogen-type carboxylic acid anhydride, you may use a commercially available thing suitably.

(Aliphatic tertiary amine)
The aliphatic tertiary amine according to the present invention will be described. In the present invention, the aliphatic tertiary amine is used in combination with the halogenated carboxylic acid anhydride from the viewpoints of moderate reactivity, moderate imide ring-closing activity, and volatility. Even when such a compound other than an aliphatic tertiary amine is combined with the halogen-based carboxylic acid anhydride, it does not exhibit moderate reactivity, moderate imide ring-closing activity, and volatility, and is sufficiently flexible and light transmissive. High polyimide cannot be produced.

As such an aliphatic tertiary amine, the following general formula (5):

[In Formula (5), each R ³ independently represents an aliphatic group. ]
It is preferable that it is a compound represented by these.

R ³ in the general formula (5) may be the same or different and each may be an aliphatic group. Examples of the aliphatic group used as R ³ include a linear aliphatic group having 1 to 10 carbon atoms and a carbon number of 1 from the viewpoint of moderate reactivity, moderate imide ring-closing activity, and volatility. Ten branched aliphatic groups are preferred. Further, each R ³ is more preferably an alkyl group having 1 to 5 carbon atoms, and particularly preferably an alkyl group having 1 to 2 carbon atoms. In addition, when the carbon number of such an alkyl group exceeds the upper limit, there is a tendency that moderate reactivity, moderate imide ring-closing activity and volatility are not exhibited.

Examples of the aliphatic tertiary amine include trimethylamine, triethylamine, tripropylamine, triisopropylamine, diisopropylethylamine, tributylamine, tripentylamine, DBU, DBN, DABCO, and moderate reactivity. From the viewpoint of moderate imide ring-closing activity and volatility, trimethylamine, triethylamine, tripropylamine, triisopropylamine, and diisopropylethylamine are more preferable, and trimethylamine, triethylamine, and diisopropylethylamine are more preferable. In addition, such an aliphatic tertiary amine may be used individually by 1 type, or may be used in combination of 2 or more type.

The method for producing such an aliphatic tertiary amine is not particularly limited, and a known method can be appropriately employed. Moreover, you may use a commercially available thing suitably as such an aliphatic type | system | group tertiary amine.

(blend)
Next, the mixture according to the present invention will be described. The mixture concerning this invention is a mixture containing the polyamic acid which has a repeating unit represented by the said General formula (1), the said halogen-type carboxylic anhydride, and the said aliphatic tertiary amine. Thus, in the mixture according to the present invention, the halogenated carboxylic acid anhydride and the aliphatic tertiary amine are selected and combined from so-called imidizing agents. As described above, since the mixture is selected and used in combination with the halogenated carboxylic acid anhydride and the aliphatic tertiary amine, the reason is not necessarily clear, but the temperature is relatively low (depending on the monomer). However, for example, a low temperature of about 300 ° C. or lower, preferably a low temperature of about 250 ° C. or lower, more preferably a low temperature of about 230 ° C. or lower, more preferably a low temperature of about 210 ° C. or lower). However, the polyamic acid can be efficiently imidized, and an alicyclic polyimide having a sufficiently high light transmittance can be efficiently produced.

Such a mixture may contain an organic solvent from the viewpoint of easy application and improved processing performance. As such an organic solvent, it is preferable to use an organic solvent similar to that described as the organic solvent used in the step of obtaining the polyamic acid. Further, such a mixture is not particularly limited, but from the viewpoint of improving the production efficiency of the polyimide, a step of obtaining the polyamic acid is adopted, and the above general formula (3) is used in an organic solvent. A reaction liquid (containing a polyamic acid having a repeating unit represented by the above general formula (1) by reacting the tetracarboxylic dianhydride represented by the aromatic diamine represented by the above general formula (4). After the reaction solution is obtained, the reaction solution is used as it is, and the one obtained by adding the halogen-based carboxylic acid anhydride and the aliphatic tertiary amine to the reaction solution can be suitably used. .

In such a mixture, the content of the halogen-based carboxylic acid anhydride in the mixture is 0.01 to 4.0 mol (more preferably, 0.00 mol) with respect to 1 mol of the polyamic acid repeating unit. 1 to 3.0, more preferably 0.2 to 2.0). When the content ratio of such a halogenated carboxylic acid anhydride is less than the lower limit, the effect obtained by adding the halogenated carboxylic acid anhydride tends to be insufficient (additional effect is reduced), When the upper limit is exceeded, polymer precipitation occurs in the mixture, and the mixture tends to be non-uniform. If the mixture is non-uniform, uniform casting (cast film formation) becomes impossible. And when such a cast-coated film is dried, it becomes impossible to produce a film (dried film) made of a mixture of uniform polyamic acid and polyimide, resulting in a transparent and uniform film. The film cannot be obtained.

In the mixture according to the present invention, the content of the aliphatic tertiary amine in the mixture is 0.01 to 4.0 mol (more preferably 0 mol) per mol of the polyamic acid repeating unit. 0.1 to 3.0, more preferably 0.2 to 2.0). If the content ratio of the aliphatic tertiary amine is less than the lower limit, the effect obtained by adding the aliphatic tertiary amine tends to be insufficient (addition effect is reduced), If the upper limit is exceeded, polymer precipitation occurs in the mixture, and the mixture tends to be non-uniform.

In addition, when such a mixture contains an organic solvent, the content of the polyamic acid in the mixture is preferably 1 to 50% by mass, and preferably 10 to 30% by mass. If the content of such polyimide acid is less than the lower limit, the chemical imidation reaction tends not to proceed sufficiently in the mixture. On the other hand, even if the upper limit is exceeded, the chemical imidization reaction also proceeds sufficiently. It tends to disappear.

In addition, the method for producing such a mixture is not particularly limited, but adopting the step of obtaining the polyamic acid, the tetracarboxylic dianhydride represented by the above general formula (3) and the above general formula in an organic solvent. After reacting with the aromatic diamine represented by the formula (4) to obtain a reaction liquid (reaction liquid containing a polyamic acid having a repeating unit represented by the general formula (1)), the reaction liquid is Utilizing the method as it is, the method (A) of adding the halogenated carboxylic acid anhydride and the aliphatic tertiary amine to the reaction solution, or the step of obtaining the polyamic acid is adopted. ) Is obtained, and then the polyamic acid is isolated from the reaction liquid, and then the isolated polyamic acid is dissolved in an organic solvent to obtain a polyamic acid. The Lysates obtained with a method may be adopted (B) of adding said halogen-containing carboxylic acid anhydride and the aliphatic tertiary amine in its solution. Of these methods, the method (A) described above is preferably employed from the viewpoint of more efficiently producing polyimide.

In the method for producing such a mixture, the halogenated carboxylic acid anhydride and the aliphatic tertiary amine are added to the polyamic acid-containing liquid containing the polyamic acid (the reaction liquid or the solution). The order of addition is not particularly limited and may be added at the same time. However, it is preferable to add the halogenated carboxylic acid anhydride after adding the aliphatic tertiary amine. By adding the halogenated carboxylic acid anhydride and the aliphatic tertiary amine in this order, an appropriate reactivity (condensability) is exhibited during chemical imidization, and heating at a relatively low temperature (curing). Imide ring-closing activity is obtained at the time of ringing, and as a result, it becomes possible to produce a polyimide having sufficient flexibility by heating at a relatively low temperature.

Moreover, in the manufacturing method of the said mixture, it does not restrict | limit especially as atmospheric conditions at the time of adding the said halogen-type carboxylic anhydride and the said aliphatic tertiary amine, It implements under inert gas, such as nitrogen. It is good also as general chemical imidation conditions, such as. In the method for producing the mixture, the temperature condition for adding the halogenated carboxylic acid anhydride and the aliphatic tertiary amine is not particularly limited, but is −30 ° C. to 80 ° C. Preferably, the temperature is 0 ° C. to 60 ° C. If such temperature condition is less than the lower limit, viscosity tends to increase or solidify and stirring tends to be impossible.On the other hand, if the upper limit is exceeded, non-uniformity due to precipitation due to polyimide formation or amide bond of polyamic acid occurs. There is a tendency for molecular weight reduction due to cleavage. In order to satisfy such a temperature condition, for example, while cooling the polyamic acid-containing liquid (the reaction liquid or the solution) in an ice bath, the halogen-based carboxylic acid anhydride and the aliphatic tertiary class are used. An amine may be added.

Further, in the production of the mixture as described above, by adding the halogen-based carboxylic acid anhydride and the aliphatic tertiary amine to the polyamic acid-containing liquid (the reaction liquid or the solution), It is possible to partially produce polyimide by chemical imidization. Therefore, in producing the mixture as described above, the polyamic acid-containing solution (the reaction solution or the solution) is added to the polyamic acid-containing solution (the reaction solution or the solution) from the viewpoint of obtaining a more uniform mixture while partially generating polyimide in the mixture. On the other hand, it is preferable to carry out a step of mixing (stirring) the mixture after adding the halogen-based carboxylic acid anhydride and the aliphatic tertiary amine. In addition, such mixing (stirring) is performed under a temperature condition of less than 80 ° C. (more preferably, a temperature condition of −30 to 60 ° C., particularly preferably a temperature condition of 0 ° C. to 40 ° C.). The step of stirring) is more preferable. By carrying out such a step of mixing (stirring), it is possible to obtain a uniform mixture while partially generating polyimide in the mixture by a so-called chemical imidation reaction. In the present invention, since the halogenated carboxylic acid anhydride and the aliphatic tertiary amine are used in combination, even if a polyimide is partially formed, the mixture should be sufficiently uniform. Is possible. Therefore, when the mixture obtained by mixing under the above temperature conditions is heated and imidized, it becomes possible to produce polyimide by heating at a relatively low temperature, and a polyimide having sufficiently high light transmittance is more efficiently produced. It tends to be possible to manufacture. Here, if the temperature condition at the time of mixing (stirring) is less than the lower limit, the partial chemical imidization reaction does not proceed sufficiently in the mixture, and heating at a high temperature is necessary for final imidization. On the other hand, if the upper limit is exceeded, imidization proceeds more than necessary, so that the polymer precipitates and the mixture becomes non-uniform, resulting in a uniform film. There is a tendency to become impossible.

Further, when the halogenated carboxylic acid anhydride and the aliphatic tertiary amine are added to the reaction solution containing the polyamic acid or the solution containing the polyamic acid in this way and then mixed. The time for performing the mixing step (reaction time for performing the chemical imidization reaction in the mixture) is preferably 1 to 50 hours, and more preferably 12 to 24 hours. If such mixing time (reaction time) is less than the lower limit, in the mixture, the chemical imidation reaction does not proceed sufficiently, and there is a tendency that it is necessary to heat at a high temperature in the final thermal imidation, On the other hand, when the upper limit is exceeded, chemical imidization proceeds excessively, the mixture becomes non-uniform, and there is a tendency that a uniform film cannot be obtained.

In addition, as atmospheric conditions when mixing after adding the halogen-based carboxylic acid anhydride and the aliphatic tertiary amine, the prevention of coloring due to oxygen in the air, the prevention of mixing of water vapor in the air to reduce the molecular weight From the viewpoint, it is preferable to use an inert gas condition such as nitrogen or a dry condition (for example, to perform mixing in a dry box). The pressure conditions for producing the mixture are not particularly limited, but are preferably 0.01 MPa to 1 MPa, more preferably 0.1 MPa to 0.3 MPa. If the pressure is less than the lower limit, the solvent, the halogenated carboxylic acid anhydride, or the aliphatic tertiary amine tends to vaporize. On the other hand, if the pressure exceeds the upper limit, the polymerization operation or the halogenated Addition of a carboxylic acid anhydride or the aliphatic tertiary amine tends to be difficult.

Thus, as the mixture, the halogenated carboxylic acid anhydride and the aliphatic three-component solution are used for the polyamic acid-containing liquid (the reaction liquid containing the polyamic acid or the solution containing the polyamic acid). It is preferable to use a mixture obtained by mixing (stirring) under the temperature condition of less than 80 ° C. for 1 hour to 50 hours after adding the primary amine. In addition, since the imidization (chemical imidation) proceeds partially in the mixture as described above, the mixture after stirring has a repeating unit represented by the general formula (2) described later. It contains polyimide and the polyamic acid represented by the general formula (1).

(Imidization process of polyamic acid)
Next, the imidization process of a polyamic acid is demonstrated. In the present invention, by imidizing the polyamic acid using the mixture, the following general formula (2):

The polyimide which has a repeating unit represented by this is obtained. The above general formula (2), ^{R 1} and ^{R 2} are each the in formula (1) the same meaning as ^{R 1} and ^{R 2} in (also synonymous suitable.)
The imidization method is not particularly limited as long as it is a method capable of imidizing the polyamic acid using the mixture, and a known method can be appropriately employed, but the mixture is heated. It is preferable to include a process. Such a heating step allows the thermal imidization reaction to proceed efficiently. Further, as the mixture used in such a heating step, it is preferable to use a mixture obtained by partially advancing the chemical imidation reaction of the polyamic acid in the mixture. From this viewpoint, the polyamic acid-containing liquid is used. Utilizing (mixing (stirring) after adding the halogenated carboxylic acid anhydride and the aliphatic tertiary amine to the reaction solution containing the polyamic acid or the solution containing the polyamic acid) More preferably, after adding the halogen-based carboxylic acid anhydride and the aliphatic tertiary amine to the polyamic acid-containing liquid, mixing (stirring) at a temperature of less than 80 ° C. for 1 hour to 50 hours It is more preferable to use the above. That is, in the present invention, in the step of imidizing the polyamic acid, the step of stirring (mixing) the mixture (the step of mixing (stirring) described in the above-described method for producing a mixture) and the mixture are heated. It is preferable to include a process. As a result, the chemical imidization reaction of the polyamic acid partially proceeds in the mixture, and then the mixture can be heated to allow the thermal imidization reaction to proceed. It is possible to manufacture polyimide well.

In addition, the step of heating such a mixture is performed at a temperature lower than the glass transition temperature (Tg) of the resulting polyimide by 80 to 300 ° C. (more preferably, from the viewpoint of preventing coloring of the polyimide by heating at a lower temperature. The step is preferably a step of heating (firing) the mixture at a temperature 100 to 200 ° C. lower than Tg, more preferably a temperature 120 to 180 ° C. lower than Tg. When such a heating temperature exceeds the upper limit, it tends to be difficult to sufficiently suppress the coloring of the polyimide. On the other hand, when the heating temperature is lower than the lower limit, imidation does not proceed sufficiently. By imidating by heating at such a heating temperature, it is derived from protons of carboxylic acid (—COOH) derived from polyamic acid or amide (NHCO) in NMR measurement while heating at a relatively low temperature. It is possible to sufficiently imidize the polyamic acid so that protons are not observed. Further, according to the present invention, it is possible to produce a highly flexible polyimide by heating at a low temperature that is 80 to 300 ° C. lower than the glass transition temperature (Tg) of the polyimide.

In the present invention, the “polyimide glass transition temperature (Tg)” can be determined by the following glass transition temperature (Tg) measurement method. That is, as a method for measuring the glass transition temperature (Tg), after forming a film-shaped polyimide and forming films each having a length of 20 mm, a width of 5 mm, and a thickness of 0.02 mm (20 μm), the film is formed. After vacuum drying (120 ° C., 1 hour (Hr)) and heat treatment in a nitrogen atmosphere at 200 ° C. for 1 hour (Hr) to obtain a sample (dry film), the sample is used as a thermomechanical measurement device. Using an analyzer (trade name “TMA8310” manufactured by Rigaku), the change in the sample at 30 ° C. to 400 ° C. was measured under the nitrogen atmosphere, using the penetration mode and the heating rate of 10 ° C./min. Can be used.

Further, when imidizing the polyamic acid by heating the mixture, it is desired to heat (sinter) at a lower temperature from the viewpoint of industrialization and cost reduction. From such a viewpoint, in the step of heating the mixture, the heating temperature is preferably 300 ° C. or less, more preferably 80 to 250 ° C., further preferably 100 to 230 ° C., ˜210 ° C. is particularly preferred. When such a heating temperature exceeds the upper limit, it becomes difficult to sufficiently reduce the cost due to an increase in the heating temperature, or it tends to be difficult to suppress coloring at a very high level. On the other hand, if the amount is less than the lower limit, the reaction proceeds slowly, and it tends to be difficult to produce a flexible polyimide efficiently. Even in the case of thermal imidization by heating at such a low temperature (for example, 230 ° C. or lower), since the mixture is used in the present invention, a polyimide having sufficient mechanical properties such as flexibility. Can also be manufactured.

In addition, the atmospheric conditions for carrying out the step of heating the mixture include an inert gas atmosphere such as nitrogen gas or under vacuum from the viewpoint of preventing coloring due to oxygen in the air and molecular weight reduction due to water vapor in the air. It is preferable that The pressure condition for carrying out the step of heating the mixture is not particularly limited, but is preferably 0.01 hPa to 1 MPa, more preferably 0.1 hPa to 0.3 MPa. . If the pressure is less than the lower limit, the solvent, the halogenated carboxylic acid anhydride, and the aliphatic tertiary amine tend to be instantly vaporized to generate bubbles and voids, and on the other hand, exceed the upper limit. In addition, it tends to be difficult to remove the solvent, the halogen-based carboxylic acid anhydride, and the aliphatic tertiary amine.

In addition, in the case where the step of heating the mixture is performed, when the mixture includes a solvent (for example, in the case of a solution), it is preferable to perform a drying process before performing the heat treatment. By such a drying treatment, the polyamic acid having the repeating unit represented by the general formula (1) is isolated in the form of a film or the like, and then heat treatment can be performed.

The temperature condition in such a drying process is preferably −20 to 80 ° C., more preferably 0 to 60 ° C. If the temperature condition in such a drying process is less than the lower limit, the solvent tends to be unable to be removed when the mixture contains a solvent. On the other hand, if the mixture exceeds the upper limit, volatile components such as the solvent boil and bubbles are formed during film formation. And tends to be a film containing voids. Further, the atmosphere in such a drying treatment method is preferably an inert gas atmosphere (for example, a nitrogen atmosphere). From the viewpoint of more efficient drying, the pressure condition in such a drying process is preferably 0.01 hPa to 0.1 MPa. In this case, for example, in the case of producing a film-like polyimide, the mixture may be applied on a substrate, followed by the drying treatment and the heat treatment, and the film-like polyimide may be produced by a simple method. Is possible.

Moreover, when manufacturing a film-like polyimide, it is not restrict | limited especially as a base material for apply | coating the said mixture, According to the shape etc. of the film which consists of the target polyimide, it can be used for film formation A base material (for example, a glass plate or a metal plate) made of any known material can be used as appropriate.

In addition, when the mixture is applied to the substrate in this way, the application method is not particularly limited, and a known method (such as a casting method) can be appropriately employed. For example, a casting method, a spin coating method, a spraying method can be used. A coating method, a dip coating method, a dropping method, a gravure printing method, a screen printing method, a relief printing method, a die coating method, a curtain coating method, an ink jet method, and the like can also be appropriately employed.

Further, when the mixture is applied on the substrate, the thickness of the coating film of the mixture is preferably 1 to 200 μm, more preferably 5 to 100 μm after drying. If the thickness of the coating film of such a mixture is less than the lower limit, mechanical strength tends to decrease and the film tends to be weakened. On the other hand, if the thickness exceeds the upper limit, film forming tends to be difficult.

Further, as the imidization method, from the viewpoint of production efficiency, after carrying out the step of obtaining the polyamic acid, the tetracarboxylic dianhydride represented by the general formula (3) and the general A reaction solution obtained by reacting with an aromatic diamine represented by the formula (4) (a reaction solution containing a polyamic acid having a repeating unit represented by the above general formula (1)) is used as it is (the above general A polyamic acid having a repeating unit represented by the formula (1) is used without isolation), and the halogenated carboxylic acid anhydride and the aliphatic tertiary amine are added to the reaction solution to obtain a mixture It is preferable to perform the said heat processing (process of heating the said mixture), after giving a drying process with respect to this mixture and removing a solvent after obtaining this. In addition, in the process of obtaining this mixture, it is preferable to perform the process of mixing (stirring) as mentioned above.

Moreover, the polyimide obtained by the present invention may contain other repeating units in addition to the repeating unit represented by the general formula (2). In this case, for example, in the step of obtaining the polyamic acid, another tetracarboxylic dianhydride is used together with the tetracarboxylic dianhydride represented by the general formula (3), and these are combined with the aromatic diamine. What is necessary is just to make it react. As other tetracarboxylic dianhydrides other than the tetracarboxylic dianhydride represented by the above general formula (3), known tetracarboxylic dianhydrides can be appropriately used. For example, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride, 1,4, 5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride, 3,3 ', 4,4'-Dimethyldiphenylsilanetetracarboxylic dianhydride, 3,3', 4,4'-tetraphenylsilanetetracarboxylic dianhydride, 1,2,3,4-furantetracarboxylic acid dianhydride Anhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, 4,4′- Bis (3,4-dicarboxyphenoxy ) Diphenylpropane dianhydride, 3,3 ′, 4,4′-perfluoroisopropylidene diphthalic dianhydride, 4,4 ′-(2,2-hexafluoroisopropylidene) diphthalic dianhydride, 3 , 3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine oxide dianhydride, p-phenylene -Bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4'-diphenyl ether dianhydride, bis (triphenylphthalic acid) Acid) -4,4′-diphenylmethane dianhydride, and the like. In addition, when using such aromatic tetracarboxylic acid, in order to prevent the coloring by CT, the usage-amount is suitably changed within the range in which the obtained polyimide can have sufficient transparency. It is preferable to do.

[Polyimide]
The polyimide of this invention is a polyimide obtained by the manufacturing method of the polyimide of the said invention.

Such a polyimide preferably has a glass transition temperature (Tg) of 250 ° C. or higher, more preferably 300 to 500 ° C. If the glass transition temperature (Tg) is less than the lower limit, sufficient heat resistance tends to be difficult to achieve, and if it exceeds the upper limit, it tends to be difficult to produce a polyimide having such characteristics. It is in. The glass transition temperature (Tg) of such a polyimide can be determined by employing the above-described method for measuring the glass transition temperature (Tg).

Furthermore, the number average molecular weight (Mn) of such a polyimide is preferably 1,000 to 1,000,000, more preferably 10,000 to 100,000, in terms of polystyrene. When the number average molecular weight is less than the lower limit, sufficient heat resistance tends to be difficult to achieve, and when it exceeds the upper limit, processing tends to be difficult.

In addition, the weight average molecular weight (Mw) of such a polyimide is preferably 1000 to 5000000 in terms of polystyrene. Moreover, as a lower limit of the numerical range of such a weight average molecular weight (Mw), it is more preferable that it is 1000, It is still more preferable that it is 5000, It is especially preferable that it is 10,000. Moreover, as an upper limit of the numerical range of a weight average molecular weight (Mw), it is more preferable that it is 5000000, It is further more preferable that it is 500000, It is especially preferable that it is 50000. If the weight average molecular weight is less than the lower limit, sufficient heat resistance tends to be difficult to achieve, and if it exceeds the upper limit, processing tends to be difficult.

Further, the molecular weight distribution (Mw / Mn) of such a polyimide is preferably 1.1 to 5.0, and more preferably 1.5 to 3.0. If the molecular weight distribution is less than the lower limit, it tends to be difficult to produce, while if it exceeds the upper limit, it tends to be difficult to obtain a uniform film. The molecular weight (Mw or Mn) and molecular weight distribution (Mw / Mn) of such polyimide are measured by gel permeation chromatography (GPC, manufactured by Tosoh Corporation, trade name: HLC-8020 / four columns). : Tosoh Co., Ltd., trade name: TSK gel GMH _HR, etc.), and measured using polystyrene (THF), chloroform, N, N-dimethylformamide (DMF), etc. as a solvent, and converted to polystyrene. be able to.

Further, such a polyimide preferably has a linear expansion coefficient of −10 to 100 ppm / ° C. (more preferably 0 to 80 ppm / ° C.). If the linear expansion coefficient is less than the lower limit, distortion tends to occur when compounding with other materials such as metals, metal oxides, and glass or other inorganic substances, and on the other hand, exceeding the upper limit is less than the lower limit. In the same manner as above, distortion tends to occur when compounding with other materials such as metals, metal oxides and inorganic substances such as glass.

The linear expansion coefficient of such a polyimide is 20 mm in length, 5 mm in width, and 0.02 mm (20 μm) in thickness. A thermomechanical analyzer (trade name “TMA8310” manufactured by Rigaku) is used as a measuring device. Utilizing a tensile mode (49 mN) under a nitrogen atmosphere and a temperature rising rate of 5 ° C./min, the change in the length of the sample in the vertical direction at 50 ° C. to 200 ° C. is measured. A value obtained by obtaining an average value of changes in length per 1 ° C. in a temperature range of from 0 ° C. to 200 ° C. can be adopted. The glass transition temperature and the linear expansion coefficient of the polyimide may be appropriately changed from ^one of R ¹ to R ^{2 in} the general formula (2) or a plurality of repeating units represented by the general formula (2). By containing seeds (two or more), it can be within the above numerical range.

Such polyimide is preferably highly transparent, and has an average transmittance of light in the wavelength region of 400 to 800 nm of 80% or more (more preferably 85% or more, particularly preferably 87% or more). Is more preferable. Such average transmittance can be sufficiently achieved by lowering the heating temperature during production. As such transmittance, a value measured using a trade name “UV-visible near-infrared spectrophotometer V-570” manufactured by JASCO Corporation can be adopted as a measuring apparatus.

Such a polyimide preferably has a thermal decomposition temperature (Td) of 450 ° C. or higher, more preferably 480 to 600 ° C. If such a thermal decomposition temperature (Td) is less than the lower limit, sufficient heat resistance tends to be difficult to achieve, and if it exceeds the upper limit, it is difficult to produce a polyimide having such characteristics. There is a tendency. In addition, such a thermal decomposition temperature (Td) uses a TG / DTA220 thermogravimetric analyzer (manufactured by SII Nano Technology Co., Ltd.), in a nitrogen stream (200 mL / min), and a temperature rising rate of 10 ° C. / min. It can be determined by measuring the temperature at the intersection of the tangent lines drawn on the decomposition curve before and after thermal decomposition under the conditions of

Such a polyimide preferably has a 5% weight loss temperature of 400 ° C. or higher, more preferably 450 to 550 ° C. If such a 5% weight loss temperature is less than the lower limit, sufficient heat resistance tends to be difficult to achieve, and if it exceeds the upper limit, it tends to be difficult to produce a polyimide having such characteristics. It is in. Such 5% weight reduction temperature is obtained by gradually heating from room temperature (25 ° C.) while flowing nitrogen gas in a nitrogen gas atmosphere and measuring the temperature at which the weight of the used sample is reduced by 5%. Can be sought. In addition, as such a sample, it is preferable to prepare and use five films of 2 mm in length, 2 mm in width, and 20 micrometers in thickness.

Thus, since the polyimide of the present invention is obtained by adopting the above-described method for producing the polyimide of the present invention, coloring is sufficiently prevented, sufficiently high level of light transmission and sufficiently high level of transparency. It has heat resistance. Moreover, since the polyimide of this invention is obtained by employ | adopting the manufacturing method of the polyimide of the said invention, it has sufficient softness | flexibility. Therefore, the polyimide of the present invention can be suitably used as a resin material used in place of glass, for example, for producing a substrate made of a transparent resin material used as a substrate for mobile devices such as smartphones and tablet terminals. It can be suitably used for the material.

Hereinafter, the present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to the following examples.

First, a method for evaluating properties of compounds, films and the like obtained in each synthesis example, each example, and each comparative example will be described.

<Identification of molecular structure>
Identification of the molecular structure of the compound obtained in each example or the like was performed by infrared spectroscopy (manufactured by JASCO Corporation, FT / IR-460, FT / IR-4100, Thermo Fisher Scientific Co., Ltd., NICOLET 380FT). -IR) and an NMR measuring apparatus (trade name: UNITY INOVA-600 and JEOL Ltd. JNM-Lambda500, manufactured by VARIAN) were used to measure IR and NMR spectra.

<Measurement of glass transition temperature (Tg)>
The glass transition temperature (Tg) is obtained after forming films each having a length of 20 mm, a width of 5 mm, and a thickness of 0.02 mm (20 μm) from the polyimide (film-shaped polyimide) obtained in each of Examples and Comparative Examples. The sample was dried in a vacuum (120 ° C., 1 hour (Hr)) and heat-treated at 200 ° C. for 1 hour (Hr) in a nitrogen atmosphere. Change of the sample between 30 ° C. and 400 ° C. by using a chemical analyzer (trade name “TMA8310” manufactured by Rigaku), employing a penetration mode and a heating rate of 10 ° C./min in a nitrogen atmosphere. It was measured.

<Measurement of 5% weight loss temperature>
The 5% weight loss temperatures of the polyimides obtained in the examples and comparative examples were respectively set to 5 TG / DTA7200 as a measuring device by placing 5 film-shaped samples having a length of 2 mm, a width of 2 mm, and a thickness of 20 μm in an aluminum sample pan. Using a thermogravimetric analyzer (manufactured by SII Nano Technology Co., Ltd.), the sample was heated under conditions of 10 ° C / min in the range of room temperature (25 ° C) to 600 ° C while flowing nitrogen gas. Was determined by measuring the temperature at which the weight of the product decreased by 5%.

<Measurement of intrinsic viscosity [η]>
The intrinsic viscosity [η] of the polyamic acid obtained as an intermediate in the production of films and the like in the examples and comparative examples was determined by using an automatic viscosity measuring device (trade name “VMC-252”) manufactured by Koiso Co., Ltd. Using N, dimethylacetamide as a solvent, a polyamic acid measurement sample having a concentration of 0.5 g / dL was prepared and measured under a temperature condition of 30 ° C.

<Measurement of linear expansion coefficient (CTE)>
The linear expansion coefficient was determined by forming a film having a length of 20 mm, a width of 5 mm, and a thickness of 0.02 mm (20 μm) from the polyimide (film-shaped polyimide) obtained in each example and each comparative example, and then the film. The sample (dry film) obtained by vacuum drying (120 ° C., 1 hour (Hr)) and heat treatment in a nitrogen atmosphere at 200 ° C. for 1 hour (Hr), respectively, is used as a measuring device. (Trade name “TMA8310” manufactured by Rigaku), using a tension mode (49 mN) under a nitrogen atmosphere, and a temperature rising rate of 5 ° C./min, the length of the sample at 50 ° C. to 200 ° C. Was measured, and the average value of the change in length per 1 ° C. in the temperature range of 100 ° C. to 200 ° C. was measured.

<Measurement of average transmittance of light in wavelength range of 400 to 800 nm>
The average transmittance of light in the wavelength region of 400 to 800 nm of the polyimide (film-shaped polyimide) obtained in each example and each comparative example is a product name “UV-visible near-infrared spectrophotometer manufactured by JASCO Corporation as a measuring device. The transmittance was measured using a “total V-570”, and then the average value of the transmittance of light in the wavelength region of 400 to 800 nm was obtained.

<Measurement of flexibility and strength of film>
About the flexibility and strength (mechanical strength) of the polyimide (film-shaped polyimide) obtained in each Example and each Comparative Example, a film having a size of 50 mm in length, 10 mm in width, and 0.02 mm (20 μm) in thickness. When each film is formed and then wound around a commercially available round pencil (φ [diameter]: 8 mm) 10 times (round pencil winding test), the flexible film has sufficient strength when the film does not break. Judging that it is a (flexible) film (strength: sufficient, flexibility: sufficient), conversely, if the film could not be formed, or even if the film could be formed, the film was cracked in the round pencil winding test. If it enters, it is not flexible and is a brittle film (strength: brittle, flexible: insufficient) It was judged.

Example 1
<Preparation of polyamic acid>
In a three-necked flask, 3,4′-diaminodiphenyl ether (0.40052 g, 2.000 mmol, hereinafter referred to as “3,4” -DDE ”) and N, N-dimethylacetamide (2.00 g, hereinafter, In some cases, it is referred to as “DMAc”), and the mixture was stirred with a mechanical stirrer for 10 minutes under a nitrogen stream under a temperature of 20 ° C. and a pressure of 0.1 MPa to obtain a solution. Next, the following general formula (6):

In this manner, 0.76879 g (2.00 mmol, hereinafter referred to as “acid dianhydride (A)” in some cases) represented by the following formula was introduced using a funnel. The tetracarboxylic dianhydride adhering to the funnel was poured in with DMAc (2.00 g), and the whole amount (0.76879 g) was introduced into the solution.

Next, the solution into which the tetracarboxylic dianhydride has been introduced is continuously stirred for 17 hours at a stirring speed of 30 rpm with a mechanical stirrer under a nitrogen atmosphere, a temperature of 20 ° C., and a pressure of 0.1 MPa. The tetracarboxylic dianhydride and 3,4'-DDE were reacted to produce a polyamic acid to obtain a reaction solution containing the polyamic acid. The obtained polyamic acid is a polyamic acid having a repeating unit represented by the general formula (1). In the repeating unit, R ¹ in the formula (1) is represented by the above general formula (I-9). And R ² is represented by the following general formula (II-4-1) or (II-4-2):

It is group represented by these.

In order to measure the viscosity of the polyamic acid thus obtained, a part of the liquid was sampled from the reaction liquid (a liquid containing 0.25 g of polyamic acid was sampled) and diluted with DMAc. A polyamic acid solution of 0.5 g / dL was prepared. Then, the intrinsic viscosity [η] was determined by employing the above-described method for measuring the intrinsic viscosity [η]. That is, using the polyamic acid solution prepared in this manner, and using an Ostwald viscometer (automatic viscosity measuring device (trade name “VMC-252”) manufactured by Kogai Co., Ltd.) in a constant temperature bath at 30 ° C., The viscosity (logarithmic viscosity) of the polyamic acid solution was measured. As a result, the intrinsic viscosity [η] of the obtained polyamic acid was 0.46 dL / g.

<Preparation of mixture>
Next, 2.9 g of a reaction solution containing the polyamic acid obtained in the above-described preparation step of polyamic acid (molar amount of the polyamic acid repeating unit (total amount of the repeating unit in the reaction solution): 1.0 mmol, While cooling about half of the reaction solution) in an ice bath, 139 μL (1.0 mmol) of triethylamine was added to the reaction solution. Due to the addition of triethylamine, the viscosity of the reaction solution suddenly increased, and part of the reaction solution became white and cloudy. Thus, it is considered that an amine salt of polyamic acid was produced in the reaction solution. Next, 86 μL (0.6 mmol) of trifluoroacetic anhydride was added to the reaction solution after the addition of the triethylamine. The reaction solution decreased in viscosity about 20 minutes after addition of trifluoroacetic anhydride, and became a uniform and transparent light yellow solution (mixture). Next, the obtained pale yellow solution was stirred for 12 hours at a stirring speed of 30 rpm under the conditions of nitrogen atmosphere, temperature: 20 ° C., and pressure 0.1 MPa. In this way, a mixture containing the polyamic acid, triethylamine, and trifluoroacetic anhydride was obtained.

In order to confirm the structure of the components in the mixture after stirring, a part of the mixture obtained after stirring was taken out and reprecipitated in methanol to obtain a white solid, which was then dried. A part of the sample was dissolved in DMSO-d ₆ to prepare a sample for NMR. Then, using such a dried sample and an NMR sample, IR and ¹ H-NMR spectra were measured using the method described in the above-described molecular structure identification method. Among the obtained results, the IR spectrum of the component (the reprecipitate) in the mixture is shown in FIG. 1, the ¹ H-NMR spectrum of the component (the reprecipitate) in the mixture is shown in FIG. FIG. 3 shows an enlarged view of the vicinity of 6 ppm to 13 ppm of the ¹ H-NMR spectrum shown in FIG. From the results of such measurements (results shown in FIGS. 1 to 3), the protons (around 12 ppm) of carboxylic acid (—COOH) derived from polyamic acid and the protons (around 10 ppm) derived from amide (NHCO) are found. It was observed that the ring closure rate was 32% from the integrated intensity of the polyamic acid. From these results, it was found that the polyamic acid in the mixture was partially imidized. In the above mixture, polyimide did not precipitate and was a sufficiently uniform solution.

<Preparation of polyimide>
Next, after applying 0.6 mL of the mixture obtained by the preparation step of the mixture onto the surface of the glass substrate (length 75 mm, width 25 mm) by casting (coating by a casting method), 80 ° C. The solvent (DMAc) was removed by allowing to stand for 2 hours under a pressure of 1 hPa under a temperature condition to obtain a dry coating film (thickness 20 μm) of the mixture. Next, the dried coating film of the mixture was heat-treated for 1 hour under a pressure condition of 1 hPa and a nitrogen atmosphere at 200 ° C. to obtain a film. The obtained film was a flexible transparent film having sufficient strength (mechanical strength).

In order to specify the structure of the components forming the film thus obtained, a part of the obtained film was dissolved in deuterated chloroform to form an NMR sample, and a part of the film was taken out. Using the sample (IR sample) and the NMR sample obtained as described above, IR and ¹ H-NMR spectra were obtained using the method described in the above-mentioned molecular structure identification method. It was measured. Among the obtained results, the IR spectrum of the constituent components of the film is shown in FIG. 4, the ¹ H-NMR spectrum of the constituent components of the film is shown in FIG. 5, and the vicinity of 6 ppm of the ¹ H-NMR spectrum shown in FIG. An enlarged view around ˜13 ppm is shown in FIG. From the results of such measurements (results shown in FIGS. 4 to 6), when the cyclization rate is measured, protons of carboxylic acid (—COOH) derived from amic acid (around 12 ppm) and protons derived from amide (NHCO) Since it was not observed at all (around 10 ppm), it was clarified that imidization was complete. From these results, the obtained film is a repeating unit represented by the general formula (2) (in the formula (2), R ¹ is a group represented by the general formula (I-9), and R ² is a group having a general formula (II-4-1) or (II-4-2) below).

Moreover, as a result of measuring the glass transition temperature of the polyimide (film) thus obtained by adopting the measurement method of the glass transition temperature (Tg) described above, the Tg of the obtained polyimide (film) is 333 ° C. Met. Moreover, as a result of measuring the linear expansion coefficient of the obtained polyimide (film) by adopting the above-described method of measuring the linear expansion coefficient (CTE), the CTE of the obtained polyimide (film) was 56 ppm / K. . Further, when the average transmittance and the 5% weight reduction temperature were determined by the measurement method described above, the average transmittance of light in the wavelength region of 400 to 800 nm of the obtained polyimide (film) was 88%, which was 5% weight. The decrease temperature was 488 ° C.

(Example 2)
<Preparation of polyamic acid>
A method similar to the method of “Preparation of polyamic acid” employed in Example 1 was employed to obtain a reaction solution containing polyamic acid.

<Preparation of mixture>
Next, 2.9 g of the reaction solution containing the polyamic acid obtained in the above-described preparation step of the polyamic acid (molar amount of the polyamic acid repeating unit: 1.0 mmol, about half of the reaction solution) was cooled in an ice bath. Then, after sequentially adding 278 μL (2.0 mmol) of triethylamine and 287 μL (2.0 mmol) of trifluoroacetic anhydride, stirring was performed at 30 rpm for 23 hours under conditions of nitrogen atmosphere, temperature: 20 ° C., and pressure of 0.1 MPa. The mixture was stirred at a speed to obtain a mixture containing the polyamic acid, triethylamine, and trifluoroacetic anhydride. In addition, as a result of such stirring, the obtained mixture became a uniform and transparent light yellow solution.

In order to confirm the structure of the components in the mixture after stirring, IR and ¹ H-NMR spectra were measured in the same manner as in Example 1. Among the obtained results, the IR spectrum of the component (the reprecipitate) in the mixture is shown in FIG. 7, the ¹ H-NMR spectrum of the component (the reprecipitate) in the mixture is shown in FIG. FIG. 9 shows an enlarged view of the vicinity of 6 ppm to 13 ppm of the ¹ H-NMR spectrum shown in FIG. From the results of such measurements (results shown in FIGS. 8 to 9), in the re-precipitate, the carboxylic acid (—COOH) protons (around 12 ppm) derived from polyamic acid and the amide (NHCO) are derived. Protons (around 10 ppm) were observed, and it was confirmed from the integrated intensity that the ring closure rate of the polyamic acid was 40%. From these results, it was found that the polyamic acid in the mixture was partially imidized. In the mixture, polyimide did not precipitate and was a sufficiently uniform liquid.

<Preparation of polyimide>
Next, a polyimide (film) is employed by adopting the same method as the “preparation of polyimide” employed in Example 1, except that the mixture obtained by the above-described mixture preparation step is used as the mixture. Got. The obtained film was a flexible transparent film having sufficient strength (mechanical strength).

To identify the structure of the components forming such a film, and IR and ^{1 H-NMR} spectrum in the same manner as in Example 1. Of the obtained results, the IR spectrum of the constituent components of the film is shown in FIG. 10, the ¹ H-NMR spectrum of the constituent components of the film is shown in FIG. 11, and around 6 ppm of the ¹ H-NMR spectrum shown in FIG. An enlarged view of around 13 ppm is shown in FIG. From the results of such measurements (results shown in FIGS. 10 to 12), when the cyclization rate was measured, protons of carboxylic acid (—COOH) derived from amic acid (around 12 ppm) and protons derived from amide (NHCO) Since it was not observed at all (around 10 ppm), it was clarified that imidization was complete. From these results, the obtained film is a repeating unit represented by the general formula (2) (in the formula (2), R ¹ is a group represented by the general formula (I-9), and R ² is a group having a general formula (II-4-1) or (II-4-2) below).

Similarly to Example 1, the obtained polyimide (film) had a glass transition temperature (Tg), a coefficient of linear expansion (CTE), an average transmittance of light in the wavelength region of 400 to 800 nm, and a 5% weight reduction temperature. As a result, Tg was 333 ° C., CTE was 57 ppm / K, the average transmittance was 88%, and the 5% weight loss temperature was 484 ° C.

Example 3
<Preparation of polyamic acid>
Instead of using 3,4′-diaminodiphenyl ether (0.40052 g, 2.000 mmol), 4,4′-diaminodiphenyl ether (4,4′-DDE, 0.40053 g, 2.000 mmol) was used, and acid dianhydride A method similar to the method of “Preparation of polyamic acid” employed in Example 1, except that the amount of (A) used was changed from 0.76879 g (2.00 mmol) to 0.75878 g (2.00 mmol). Was used to obtain a reaction solution containing polyamic acid.

The obtained polyamic acid is a polyamic acid having a repeating unit represented by the general formula (1), and in the repeating unit, R ¹ in the formula (1) is represented by the above general formula (I-9). And R ² is represented by the following general formula (II-4-3):

It is group represented by these. Further, when the intrinsic viscosity [η] of the polyamic acid obtained in the same manner as in Example 1 was determined using the above-described method for measuring the intrinsic viscosity [η], the intrinsic viscosity [η] was 0.87 dL / g. Met.

<Preparation of mixture>
Next, except that the reaction solution containing the polyamic acid obtained as described above was used, a method similar to the method of “Preparation of the mixture” employed in Example 1 was adopted, Obtained. The structure of the components in the mixture after stirring was measured in the same manner as in Example 1. As a result, in the ¹ H-NMR spectrum, it was derived from the proton of carboxylic acid (—COOH) derived from amic acid and amide (NHCO). Protons were observed, and it was confirmed that the ring closure rate of the polyamic acid obtained from the integrated intensity was 40%. From these results, it was found that the polyamic acid in the mixture was partially imidized. In the above mixture, polyimide did not precipitate and was a sufficiently uniform solution.

In order to specify the structure of the components forming such a film, IR and ¹ H-NMR spectra were measured in the same manner as in Example 1. Based on the measurement results of the IR and ¹ H-NMR spectra, when the ring closure rate of the polyamic acid in the obtained film was measured, protons of carboxylic acid (—COOH) derived from amic acid and amide (NHCO) From the fact that no proton derived from was observed, it was clarified that it was completely imidized. From these results, the obtained film is a repeating unit represented by the general formula (2) (in the formula (2), R ¹ is a group represented by the general formula (I-9), and And R ² is a group represented by the general formula (II-4-3)).

Similarly to Example 1, the obtained polyimide (film) had a glass transition temperature (Tg), a coefficient of linear expansion (CTE), an average transmittance of light in the wavelength region of 400 to 800 nm, and a 5% weight reduction temperature. As a result, Tg was 354 ° C., CTE was 49 ppm / K, the average transmittance was 87%, and the 5% weight loss temperature was 468 ° C.

Example 4
<Preparation of polyamic acid>
4,4′-Diaminobenzanilide (0.45452 g, 2.000 mmol, hereinafter referred to as “4,4′-DABA”) and DMAc (2.00 g) were added to a three-necked flask under a nitrogen stream. The solution was stirred for about 10 minutes with a mechanical stirrer under the conditions of temperature: 20 ° C. and pressure of 0.1 MPa. Next, 0.76878 g (2.00 mmol: acid dianhydride (A)) of the tetracarboxylic dianhydride represented by the above general formula (6) is added to the three-necked flask into which the solution is introduced. It was introduced using a funnel. The tetracarboxylic dianhydride adhering to the funnel was poured in with DMAc (2.90 g), and the entire amount (0.76878 g) was introduced into the solution.

Next, the solution into which the tetracarboxylic dianhydride has been introduced is continuously stirred for 18 hours at a stirring speed of 30 rpm with a mechanical stirrer under a nitrogen atmosphere, a temperature of 20 ° C., and a pressure of 0.1 MPa. The tetracarboxylic dianhydride and 4,4′-DABA were reacted to produce a polyamic acid to obtain a reaction liquid containing the polyamic acid. The obtained polyamic acid is a polyamic acid having a repeating unit represented by the general formula (1). In the repeating unit, R ¹ in the formula (1) is represented by the above general formula (I-9). And R ² is represented by the following general formula (II-4-4):

It is group represented by these. Further, when the intrinsic viscosity [η] of the polyamic acid obtained in the same manner as in Example 1 was determined by employing the above-described method for measuring the intrinsic viscosity [η], the intrinsic viscosity [η] was 0.77 dL / g. Met.

<Preparation of mixture>
Next, 3.1 g of the reaction solution containing the polyamic acid obtained in the above-described preparation step of the polyamic acid (amount of polyamic acid repeating unit: 1.0 mmol, about half of the reaction solution) was added with 6.0 g of DMAc. After dilution, 139 μL (1.0 mmol) of triethylamine was added to the reaction solution while cooling in an ice bath. By adding such triethylamine, the viscosity of the reaction solution suddenly increased and a part of the gel was formed, but when stirred for about 3 hours at a temperature of 20 ° C., a uniform solution was obtained. Next, 86 μL (0.6 mmol) of trifluoroacetic anhydride was added to the solution while cooling the solution in an ice bath. The solution decreased in viscosity about 20 minutes after the addition of trifluoroacetic anhydride, and became a uniform and transparent solution. Next, the obtained transparent solution was stirred for 12 hours at a stirring speed of 30 rpm under a nitrogen atmosphere, a temperature of 20 ° C., and a pressure of 0.1 MPa. In this way, a mixture containing the polyamic acid, triethylamine, and trifluoroacetic anhydride was obtained.

The structure of the components in the mixture after stirring was measured in the same manner as in Example 1. As a result, in the ¹ H-NMR spectrum, it was derived from the proton of carboxylic acid (—COOH) derived from amic acid and amide (NHCO). Protons were observed, and it was confirmed that the ring closure rate of the polyamic acid obtained from the integrated intensity was 40%. From these results, it was found that the polyamic acid in the mixture was partially imidized. In the above mixture, polyimide did not precipitate and was a sufficiently uniform solution.

In order to specify the structure of the components forming such a film, IR and ¹ H-NMR spectra were measured in the same manner as in Example 1. Based on the measurement results of the IR and ¹ H-NMR spectra, when the ring closure rate of the polyamic acid in the obtained film was measured, protons of carboxylic acid (—COOH) derived from amic acid and amide (NHCO) From the fact that no proton derived from was observed, it was clarified that it was completely imidized. From these results, the obtained film is a repeating unit represented by the general formula (2) (in the formula (2), R ¹ is a group represented by the general formula (I-9), and And R ² is a group represented by the above general formula (II-4-4)).

Similarly to Example 1, the obtained polyimide (film) had a glass transition temperature (Tg), a coefficient of linear expansion (CTE), an average transmittance of light in the wavelength region of 400 to 800 nm, and a 5% weight reduction temperature. As a result, Tg was 400 ° C. or higher, CTE was 15 ppm / K, the average transmittance was 87%, and the 5% weight loss temperature was 481 ° C.

(Comparative Example 1)
Instead of using the mixture in the polyimide preparation step without using the mixture preparation step, the reaction solution containing the polyamic acid obtained in the polyamic acid preparation step was used (with triethylamine and trifluoroacetic anhydride. In the polyimide preparation step, the polyimide was prepared in the same manner as in Example 1 except that the temperature condition during the heat treatment of the dried coating film was changed from 200 ° C. to 300 ° C. Film) was prepared. However, a flexible film was not obtained, and the obtained film was brittle.

(Comparative Example 2)
A polyimide (film) was obtained in the same manner as in Comparative Example 1 except that the temperature condition during the heat treatment of the dried coating film was changed from 300 ° C to 350 ° C. The obtained film was a flexible transparent film. As in Example 1, the obtained polyimide (film) had a glass transition temperature (Tg), a linear expansion coefficient (CTE), an average transmittance of light in the wavelength range of 400 to 800 nm, and a 5% weight loss temperature. As a result, Tg was 333 ° C., CTE was 57 ppm / K, the average transmittance was 84%, and the 5% weight loss temperature was 484 ° C.

(Comparative Example 3)
<Preparation of polyamic acid>
A method similar to the method of “Preparation of polyamic acid” employed in Example 1 was employed to obtain a reaction solution containing polyamic acid.

<Preparation of mixture>
Next, 2.9 g of the reaction solution containing the polyamic acid obtained in the above-described preparation step of the polyamic acid (molar amount of the repeating unit of polyamic acid: 1.0 mmol, about half of the reaction solution) was used for the reaction. A method similar to the “preparation of mixture” employed in Example 1 was employed except that 139 μL (1.0 mmol) of triethylamine was added to the solution, and 81 μL (1.0 mmol) of pyridine was added. A mixture containing 2.9 g of polyamic acid (1.0 mmol as the amount of the repeating unit), 81 μL (1.0 mmol) of pyridine and 86 μL (0.6 mmol) of trifluoroacetic anhydride was obtained.

<Preparation of polyimide>
Subsequently, the same method (heating temperature: 200 ° C.) as the method of “preparation of polyimide” employed in Example 1 is employed except that the mixture obtained by the above-described mixture preparation step is used as the mixture. Thus, a polyimide (film) was prepared. However, a flexible film was not obtained, and the obtained film was brittle.

(Comparative Example 4)
A polyimide (film) was prepared in the same manner as in Comparative Example 3 except that the temperature condition during the heat treatment of the dried coating film was changed from 200 ° C. to 350 ° C. in the polyimide preparation step. However, a flexible film was not obtained, and the obtained film was brittle.

(Comparative Example 5)
<Preparation of polyamic acid>
A method similar to the method of “Preparation of polyamic acid” employed in Example 1 was employed to obtain a reaction solution containing polyamic acid.

<Preparation of mixture>
Next, 2.9 g of the reaction solution containing the polyamic acid obtained in the above-described preparation step of the polyamic acid (molar amount of the polyamic acid repeating unit: 1.0 mmol, approximately half of the reaction solution) was used, and the reaction solution was used. A method similar to the method of “Preparation of mixture” employed in Example 1, except that 57 μL (0.6 mmol) of acetic anhydride was added instead of 86 μL (0.6 mmol) of trifluoroacetic anhydride. To obtain a mixture containing 2.9 g of polyamic acid (1.0 mmol as the amount of repeating units), 139 μL (1.0 mmol) of triethylamine and 57 μL (0.6 mmol) of acetic anhydride.

(Comparative Example 6)
In the polyimide preparation step, a polyimide (film) was prepared in the same manner as in Comparative Example 5 except that the temperature condition during the heat treatment of the dried coating film was changed from 200 ° C to 300 ° C. However, a flexible film was not obtained, and the obtained film was brittle.

(Comparative Example 7)
A polyimide (film) was prepared in the same manner as in Comparative Example 5 except that the temperature condition during the heat treatment of the dried coating film was changed from 200 ° C. to 350 ° C. in the polyimide preparation step. The obtained film was a flexible transparent film. As in Example 1, the obtained polyimide (film) had a glass transition temperature (Tg), a linear expansion coefficient (CTE), an average transmittance of light in the wavelength range of 400 to 800 nm, and a 5% weight loss temperature. As a result, Tg was 333 ° C., CTE was 57 ppm / K, the average transmittance was 85%, and the 5% weight loss temperature was 484 ° C.

(Comparative Example 8)
<Preparation of polyamic acid>
A method similar to the method of “Preparation of polyamic acid” employed in Example 1 was employed to obtain a reaction solution containing polyamic acid.

<Preparation of mixture>
Next, 2.9 g of the reaction solution containing the polyamic acid obtained in the above-described preparation step of the polyamic acid (amount of polyamic acid repeating unit: 1.0 mmol, about half of the reaction solution) is used in the reaction solution. Instead of adding 139 μL (1.0 mmol) of triethylamine, 81 μL (1.0 mmol) of pyridine was added. Furthermore, instead of adding 86 μL (0.6 mmol) of trifluoroacetic anhydride to the reaction solution, 57 μL (0. Except for the addition of 6 mmol), 2.9 g (1.0 mmol) of polyamic acid and 81 μL (1.0 mmol) of pyridine were employed in the same manner as in “Preparation of the mixture” employed in Example 1. And 57 μL (0.6 mmol) of acetic anhydride was obtained. However, the obtained mixture was not uniform, and a gel insoluble in DMAc was generated in the mixture, so that it could not be cast on a glass substrate and a film could not be formed.

Hereinafter, with respect to each Example and each Comparative Example, the raw material compounds and the like used for the preparation of the polyamic acid (polyamic acid) are shown in Table 1, and the characteristics and preparation conditions of the mixtures prepared in each Example and each Comparative Example are shown in Table 2. Table 3 shows the characteristics of the polyimides prepared in each Example and each Comparative Example.

As is apparent from the results shown in Tables 1 to 3, when a halogenated carboxylic acid anhydride (trifluoroacetic anhydride) and an aliphatic tertiary amine (triethylamine) are used in combination as an imidizing agent, that is, In the case where a mixture containing the polyamic acid, the halogenated carboxylic acid anhydride (trifluoroacetic anhydride) and the aliphatic tertiary amine (triethylamine) was used (Examples 1 to 4), the mixture was 200 It was confirmed that a flexible polyimide having sufficient strength (mechanical strength) was produced despite being heated (baked) at a sufficiently low temperature of ° C. Further, when the mixture containing the polyamic acid, the halogen-based carboxylic acid anhydride, and the aliphatic tertiary amine was used (Examples 1 to 4), the average transmittance of the obtained polyimide (film) was Both were 87% or more, and it was confirmed that coloring during production was sufficiently suppressed, and Tg of the obtained polyimide (film) was 330 ° C. or more, and The 5% weight loss temperature was 460 ° C. or higher, and it was confirmed that the product had sufficiently high heat resistance. From these results, in the present invention (Examples 1 to 4), by using a chemical imidization method using an imidizing agent, heating at a sufficiently low temperature of 200 ° C., sufficient flexibility, sufficiently high It has been found that it is possible to efficiently produce polyimide having excellent light transmittance and sufficiently high heat resistance.

On the other hand, when the thermal imidization is attempted by heating at 300 ° C. (temperature lower than Tg) without using any imidizing agent (Comparative Example 1), the resulting polyimide is brittle. The strength was not sufficient and it could not be used as a film. In addition, such a result shows that the thermal imidization temperature is lower than the glass transition temperature only by thermal imidation at 300 ° C., the molecular chain of the polyamic acid cannot move, and the molecular weight is improved and the imidization rate is increased. The present inventors speculate that this is because the improvement cannot be achieved. In addition, when thermal imidization is performed by heating at 350 ° C. (temperature higher than Tg) without using any imidizing agent (Comparative Example 2), sufficient strength (mechanical strength) ) Was obtained, but the transmittance was 84%, which was not always sufficient in terms of light transmittance. As described above, when the thermal imidization is performed by heating at a temperature of 350 ° C. without using any imidizing agent (Comparative Example 2), it is not always possible to sufficiently suppress the coloration. It has been found that it is impossible to produce a polyimide having a high light transmittance. From the results of Comparative Examples 1 and 2, in a system that does not use any imidizing agent as employed in the above Comparative Examples, a polyimide having sufficient flexibility when heated at 300 ° C. for about 1 hour is used. In order to obtain a polyimide that cannot be obtained and has sufficient flexibility, it is necessary to perform heating at a higher temperature (adopting heating at 350 ° C. in Comparative Example 2). It was found that it was not possible to reduce it.

Further, from the above results, even when an imidizing agent is used, in the case of using a combination of pyridine and a halogenated carboxylic acid anhydride (trifluoroacetic anhydride) (Comparative Examples 3 and 4), It was also found that a flexible polyimide having sufficient strength cannot be formed even when heated at a high temperature of 350 ° C. Further, even when an imidizing agent is used, when a combination of an aliphatic tertiary amine (triethylamine) and acetic anhydride is used (Comparative Examples 5 to 7), a heating temperature of 200 ° C. or 300 ° C. In (Comparative Examples 5 and 6), the formed polyimide becomes brittle, and a flexible film cannot be obtained. A flexible film is obtained only by a heating temperature as high as 350 ° C. as used in Comparative Example 7. It was. The heating temperature of 350 ° C. is the same temperature as the heating temperature employed in normal thermal imidization. In addition, when heat imidization was attempted by heating at a temperature condition of 350 ° C. (Comparative Example 7), the average transmittance of the obtained polyimide was 85%. When employed (Comparative Example 7), in particular, coloring is not necessarily sufficiently suppressed as compared with Examples 1 and 2 (using a heating temperature condition of 200 ° C.) using the same monomer for the production of polyimide. It has also been found that it is not always possible to produce a polyimide having a sufficiently high light transmittance. Further, even when an imidizing agent is used, in a system using a combination of pyridine and acetic anhydride (Comparative Example 8), it is not possible to even apply the mixture and even to produce a film-like polyimide. It was.

Considering the results of the production examples described in Comparative Examples 1 to 8, even when an imidizing agent is used, a combination of a halogen-based carboxylic acid anhydride and an aliphatic tertiary amine is used. In the case where the systems of Comparative Examples 1 to 8 that are not used are employed, chemical imidization cannot be fully utilized, and in order to produce a polyimide having sufficient flexibility, a relatively high temperature (for example, It can be seen that heating at a temperature higher than 300 ° C. is required.

As described above, according to the present invention, it is possible to produce an alicyclic polyimide having a sufficiently high heat resistance while utilizing a chemical imidization method, and is sufficiently flexible by heating at a relatively low temperature. It is possible to manufacture a polyimide having the property, and it is possible to more reliably prevent the polyimide from being colored at the time of manufacture. Adopting a lower heating temperature, sufficiently high light transmittance and sufficiently high heat resistance and sufficient It is possible to provide a polyimide production method that makes it possible to more efficiently and reliably produce a polyimide having such flexibility, and a polyimide obtained by the production method.

As described above, the polyimide production method of the present invention enables thermal imidization at a low temperature, which has been difficult in the past, and can suppress coloring to a minimum, so that a polyimide having extremely excellent transparency can be imparted. It becomes possible. Therefore, the polyimide production method of the present invention is, for example, a polyimide for a liquid crystal alignment film that requires a very high degree of transparency; for a transparent electrode substrate of organic EL (bottom emission type, top emission type, see-through type, etc.) Polyimide for organic EL lighting; polyimide for transparent electrode substrate of touch panel; polyimide for transparent electrode substrate of solar cell; polyimide for transparent electrode substrate of electronic paper; polyimide for transparent polyimide belt for copying machine; Various gas barrier film substrate materials; polyimide for flexible wiring substrates; polyimide for heat-resistant insulating tape; polyimide for wire enamel; polyimide for semiconductor protective coating; FPC, optical waveguide, image sensor, LED reflector, LED lighting Cover, skeleton type FPC, cover Ray film, chip-on film, high ductility composite substrate, liquid crystal alignment film, polyimide coating material (DRAM, flash memory, buffer coating material for next generation LSI, etc.), resist for semiconductor, various electrical materials, etc. Polyimide as a forming material; particularly useful as a method for producing a raw material (polyimide) used as a raw material compound (raw material monomer) for producing various battery materials such as lithium ion batteries.

Claims

The following general formula (1):

[In the formula (1), R 1 represents the following general formulas (I-1) to (I-10):

R 2 represents a group selected from the group of tetravalent substituents represented by the following general formulas (II-1) to (II-4):

(In the formula, each R 3 independently represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluorine atom, and Q represents the formula: —O—, —S—, —CO—, —CONH—, —SO 2 —, —C (CF 3 ) 2 —, —C (CH 3 ) 2 —, —CH 2 —, —O—C 6 H 4 —C (CH 3 ) 2 —C 6 H 4 —O—, —O—C 6 H 4 —SO 2 —C 6 H 4 —O—, —C (CH 3 ) 2 —C 6 H 4 —C (CH 3 ) 2 —, — This represents one selected from the group consisting of O—C 6 H 4 —C 6 H 4 —O— and —O—C 6 H 4 —O—.)
A group selected from the group of divalent substituents represented by the formula: ]
When the polyamic acid is imidized using a mixture containing a polyamic acid having a repeating unit represented by formula (II), a halogen-based carboxylic acid anhydride, and an aliphatic tertiary amine, the following general formula (2 ):

[In the formula (2), R 1 and R 2 are the same meanings as R 1 and R 2 in the general formula (1). ]
The manufacturing method of a polyimide which obtains the polyimide which has a repeating unit represented by these.
The method for producing a polyimide according to claim 1, wherein the step of imidizing the polyamic acid includes a step of heating the mixture at a temperature 80 to 300 ° C lower than the glass transition temperature of the polyimide.
The method for producing a polyimide according to claim 1 or 2, wherein a content ratio of the halogen-based carboxylic acid anhydride in the mixture is 0.01 to 4.0 moles with respect to 1 mole of the repeating unit of the polyamic acid. .
The content of the aliphatic tertiary amine in the mixture is 0.01 to 4.0 moles per mole of the polyamic acid repeating unit. The manufacturing method of the polyimide as described in.
The following general formula (3) in an organic solvent:

[In Formula (3), R 1 has the same meaning as R 1 in the general formula (1). ]
A tetracarboxylic dianhydride represented by the following general formula (4):

Wherein (4), R 2 has the same meaning as R 2 in the general formula (1). ]
The method for producing a polyimide according to any one of claims 1 to 4, further comprising a step of obtaining the polyamic acid by reacting with an aromatic diamine represented by the formula:
The halogen-based carboxylic acid anhydride is trifluoroacetic anhydride, difluoroacetic anhydride, fluoroacetic anhydride, pentafluoropropionic anhydride, heptafluorobutyric anhydride, trichloroacetic anhydride, dichloroacetic anhydride, chloroacetic anhydride, tribromoacetic anhydride, anhydrous At least one selected from dibromoacetic acid, bromoacetic anhydride, chlorodifluoroacetic anhydride, chlorotetrafluoropropionic anhydride, chlorohexafluorobutyric anhydride, and mixed acid anhydrides of these anhydrides; The method for producing polyimide according to any one of claims 1 to 5.
The aliphatic tertiary amine is represented by the following general formula (5):

[In Formula (5), each R 3 independently represents an alkyl group having 1 to 10 carbon atoms. ]
The method for producing a polyimide according to any one of claims 1 to 6, which is a tertiary amine represented by the formula:
A polyimide, which is a polyimide obtained by the method for producing a polyimide according to any one of claims 1 to 7.