JP2022183743A - Polyimide - Google Patents

Abstract

To provide a polyimide that can have a higher level of heat resistance.SOLUTION: Provided is a polyimide that is a polymer of a monomer (A) containing a tetracarboxylic dianhydride represented by the following formula (1) and/or a derivative thereof, and at least one monomer (B) selected from the group of compounds having a specific structure of 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane or the like.SELECTED DRAWING: None

Description

The present invention relates to polyimide.

2. Description of the Related Art Conventionally, in the field of display devices and the like, there has been a demand for the emergence of resin materials having high light transmittance and sufficiently high heat resistance, such as glass, as materials used for substrates and the like. In recent years, attention has been paid to polyimide as a resin material used for such glass substitute applications, and polyimide having sufficiently high heat resistance has been developed. For example, in International Publication No. 2015/163314 (Patent Document 1), the following formula (a):

[In formula (a), A is 1 selected from the group consisting of divalent aromatic groups which may have a substituent and have 6 to 30 carbon atoms forming an aromatic ring A species is shown, and a plurality of R ^z are each independently one selected from the group consisting of a hydrogen atom and an alkyl group having 1 to 10 carbon atoms. ]
A polyimide is disclosed which is a reaction product of a tetracarboxylic dianhydride represented by and an aromatic diamine. Such a polyimide described in Patent Document 1 has high light transmittance and sufficiently high heat resistance. However, even in such conventional polyimides, there is room for improvement in terms of exhibiting higher levels of heat resistance from the viewpoint of exhibiting higher properties according to the application.

WO2015/163314

The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a polyimide that can have a higher level of heat resistance.

The present inventors have made intensive studies to achieve the above object, and as a result, polyimide is a tetracarboxylic dianhydride represented by the following formula (1) and / or a monomer (A) containing a derivative thereof, By using a polymer (polycondensation product) with a monomer (B) that is a specific diamine compound, it is possible to have a higher level of heat resistance than conventional polyimides. The present inventors have found that this is the case, and have completed the present invention.

That is, the polyimide of the present invention has the following formula (1):

A monomer (A) containing a tetracarboxylic dianhydride and/or a derivative thereof represented by
3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 4 ,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diaminobenzanilide, 2,2'-bis(trifluoromethyl)benzidine and 2,2-bis(3-amino-4-hydroxy a monomer (B) which is at least one diamine compound selected from the group consisting of phenyl)hexafluoropropane;
It is characterized by being a polymer of

Further, in the present invention, the monomer (B) is 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzanilide, 2,2'-bis(trifluoromethyl) At least one diamine compound selected from the group consisting of benzidine and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane is preferred.

According to the present invention, it is possible to provide a polyimide that can have a higher level of heat resistance.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to its preferred embodiments.

The polyimide of the present invention is characterized by being a polymer of the monomer (A) and the monomer (B).

In general, polyimide is a polyamic acid (polyadduct: addition polymer: ring-opening polyadduct) obtained by subjecting a tetracarboxylic dianhydride and/or a derivative thereof to a polyaddition reaction with a diamine. is obtained by ring-closing condensation (dehydration ring-closing: intramolecular condensation). As described above, since polyimide is generally a polymer obtained by the reaction as described above, by polycondensing the monomer (A) and the monomer (B) (the polyaddition and the ring-closing condensation), It can be said that the obtained polymer (polycondensate) is a polyimide. Hereinafter, the monomer (A) and the monomer (B), which are used to form such a polymer, will be described separately.

<Monomer (A)>
The monomer (A) has the following formula (1):

It contains a tetracarboxylic dianhydride and/or a derivative thereof.

The method for obtaining the tetracarboxylic dianhydride represented by the formula (1) is not particularly limited, and is a known method (e.g., the method described in International Publication No. 2015/163314 (e.g., such international Example 5, etc.) of the Unexamined Publication, etc.) can be employed.

Further, the derivative of the tetracarboxylic dianhydride represented by the formula (1) is not particularly limited, but a diester dicarboxylic acid which is a modified product of the tetracarboxylic dianhydride represented by the formula (1) , and diester dicarboxylic acid dichloride can be preferably used. That is, when using the derivative of the tetracarboxylic dianhydride represented by the formula (1), the tetracarboxylic dianhydride represented by the formula (1) is converted to the corresponding diester dicarboxylic acid or diester It is preferable to use it after modifying|denaturing to a dicarboxylic-acid dichloride. Methods for preparing such derivatives are not particularly limited, and known methods can be employed as appropriate. When preparing a suitable diester dicarboxylic acid dichloride as a derivative of the tetracarboxylic dianhydride represented by the formula (1), for example, the tetracarboxylic dianhydride represented by the formula (1) is mixed with any alcohol By reacting with, after obtaining a diester dicarboxylic acid, by reacting with a chlorinating reagent (thionyl chloride, oxalyl chloride, etc.), a method of obtaining the corresponding diester dicarboxylic acid dichloride can be employed.

Further, the monomer (A) may contain at least one compound selected from the group consisting of tetracarboxylic dianhydrides represented by the formula (1) and derivatives thereof, and other compounds ( Other known monomeric compounds capable of producing a polyimide by reacting with the monomer (B) may further be included. Here, the monomer (A) preferably contains a tetracarboxylic dianhydride represented by the general formula (1) and/or a derivative thereof as a main component, and the tetracarboxylic acid dianhydride in the monomer (A) The content (total amount) of the tetracarboxylic dianhydride represented by the general formula (1) and its derivative is 70 mol% (more preferably 80 mol%, based on the total amount of the anhydride (total amount of the compound), more preferably 90 mol %, particularly preferably 95 mol % or more). In addition, the monomer (A) is preferably composed of the tetracarboxylic dianhydride represented by the general formula (1) because it enables more efficient production of the polyimide.

In addition, when the monomer (A) further contains other compounds other than at least one compound selected from the group consisting of tetracarboxylic dianhydrides represented by the formula (1) and derivatives thereof, such other The compound is preferably "another tetracarboxylic dianhydride" other than the tetracarboxylic dianhydride represented by formula (1) and/or a derivative thereof. Thus, the monomer (A) includes at least one compound selected from the group consisting of tetracarboxylic dianhydrides represented by the formula (1) and derivatives thereof, and other tetracarboxylic dianhydrides. and/or derivatives thereof.

Such "other tetracarboxylic dianhydrides" are not particularly limited, and known ones that can be used for the production of polyimides can be used as appropriate, such as pyromellitic anhydride and 3,4'-oxydiphthalic acid. dianhydride, 4,4'-oxydiphthalic dianhydride, biphenyl-3,4,3',4'-tetracarboxylic dianhydride, benzophenone-3,4,3',4'-tetracarboxylic dianhydride anhydride, diphenylsulfone-3,4,3′,4′-tetracarboxylic dianhydride, 4,4′-(2,2-hexafluoroisopropylidene)diphthalic dianhydride, m-terphenyl-3 ,4,3′,4′-tetracarboxylic dianhydride, p-terphenyl-3,4,3′,4′-tetracarboxylic dianhydride, cyclobutane-1,2,3,4-tetracarboxylic Acid dianhydride, 3-carboxymethyl-1,2,4-cyclopentanetricarboxylic acid 1,4:2,3-dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride (HPMDA ), butane-1,2,3,4-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, bis(1,3-dioxo-1,3-dihydroiso benzofuran-5-carboxylic acid) 1,4-phenylene, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic Acid dianhydride (CpODA), the following formulas (2) to (3):

(the compound represented by the above formula (2) (abbreviation “BNBDA”), the compound represented by the above formula (3) (abbreviation “BzDA”)), and the like. Such other tetracarboxylic dianhydrides may be used singly or in combination of two or more. When using such other tetracarboxylic dianhydrides and/or derivatives thereof, the amount of other tetracarboxylic dianhydrides and derivatives thereof relative to the total molar amount of the compounds in the monomer (A) It is preferable to use them so that the content (total amount) is 5 to 30 mol %.

<Monomer (B)>
Monomer (B) includes 3,4′-diaminodiphenyl ether (abbreviation: 3,4′-DDE), 4,4′-diaminodiphenyl ether (abbreviation: 4,4′-DDE), 1,3-bis(3- aminophenoxy)benzene (abbreviation: 1,3,3-BAB), 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (abbreviation: BAPF or HFBAPP), 4,4'- Bis(4-aminophenoxy)biphenyl (abbreviation: APBP), 4,4′-diaminobenzanilide (abbreviation: DABAN), 2,2′-bis(trifluoromethyl)benzidine (abbreviation: TFMB), 2,2- At least one diamine compound selected from the group consisting of bis(3-amino-4-hydroxyphenyl)hexafluoropropane (abbreviation: Bis-AP-AF).

Thus, at least one selected from the group consisting of 3,4'-DDE, 4,4'-DDE, 1,3,3-BAB, BAPF, APBP, DABAN, TFMB, and Bis-AP-AF By using a diamine compound as the monomer (B) and combining it with the monomer (A) to form a polyimide, it is possible to have a higher level of heat resistance than conventional polyimides. .

Further, as such a monomer (B), since it is possible to have a higher level of heat resistance, among them, 3,4'-DDE, 4,4'-DDE, DABAN, TFMB , Bis-AP-AF are more preferred. That is, the monomer (B) is at least one diamine compound selected from the group consisting of 3,4'-DDE, 4,4'-DDE, DABAN, TFMB, and Bis-AP-AF. more preferred. Further, as the monomer (B), Bis-AP-AF is more preferable from the viewpoint of increasing the solubility of the polyimide in the solvent, and TFMB is more preferable from the viewpoint of achieving both heat resistance and transparency. DABAN is preferable, and more preferable from the viewpoint of developing higher heat resistance. In the case of using Bis-AP-AF, since it has a hydroxyl group in the side chain, the solubility of the obtained polyimide in a basic solution is improved. The present inventors presume that higher effects can be obtained in terms of speed and resolution.

A method for producing such a diamine compound used as the monomer (B) is not particularly limited, and a known method can be appropriately adopted. In addition, as such a diamine compound, a commercially available one may be used as appropriate.

<Characteristics of polyimide>
The polyimide of the present invention comprises a monomer (A) containing a tetracarboxylic dianhydride represented by the formula (1) and/or a derivative thereof, 3,4′-DDE, 4,4′-DDE, 1, 3,3-BAB, BAPF, APBP, DABAN, TFMB, and a polymer (polycondensate) with a monomer (B) that is at least one diamine compound selected from the group consisting of Bis-AP-AF be.

Since such a polyimide is a polymer (polycondensate) of the monomer (A) and the monomer (B), at least the tetracarboxylic dianhydride represented by the formula (1) and / or a derivative thereof and a repeating unit formed by the reaction with the diamine compound. Therefore, such a polyimide has, for example, the following formula (10):

[In formula (10), Ar represents a residue obtained by removing two amino groups from the diamine compound used as the monomer (B). ]
It can have a repeating unit (I) represented by

Further, when the polyimide of the present invention has the repeating unit (I), the content of the repeating unit (I) is preferably 70 to 100 mol% with respect to all repeating units in the polyimide. , more preferably 90 to 100 mol %, particularly preferably 100 mol %. By making the content of the repeating unit (I) equal to or higher than the lower limit, it is possible to further improve the heat resistance as compared with the case where the content is lower than the lower limit. The monomer (A) contains the tetracarboxylic dianhydride and/or derivative thereof represented by the general formula (1) and other tetracarboxylic dianhydride and/or derivative thereof. In some cases, the polyimide of the present invention further has a structure (another repeating unit) obtained by polycondensing another tetracarboxylic dianhydride and/or derivative thereof with a diamine compound (monomer (B)). becomes.

Further, the polyimide of the present invention preferably has a glass transition temperature (Tg) of 300° C. or higher, more preferably 350° C. or higher, from the viewpoint of achieving a higher level of heat resistance. Such a glass transition temperature (Tg) can be measured in a tensile mode using a thermomechanical analyzer (trade name "TMA8311" manufactured by Rigaku Corporation).

Furthermore, the polyimide of the present invention preferably has a 5% weight loss temperature (5% Td) of 400° C. or higher, more preferably 450° C. or higher, from the viewpoint of achieving a higher level of heat resistance. . The polyimide of the present invention preferably has a 1% weight loss temperature (Td1%) of 300° C. or higher, more preferably 400° C. or higher, from the viewpoint of achieving a higher level of heat resistance. The weight loss temperature values (Td5%, Td1%) were determined by the same weight loss temperature measurement method (Td5%, Td1%) described in Examples. Adopt the desired value.

The number average molecular weight (Mn) of the polyimide of the present invention is preferably 1,000 to 1,000,000 in terms of polystyrene. The weight average molecular weight (Mw) of such polyimide is preferably 1,000 to 5,000,000 in terms of polystyrene. Furthermore, the molecular weight distribution (Mw/Mn) of such polyimide is preferably 1.1 to 5.0. When the molecular weight (Mw or Mn) and molecular weight distribution (Mw/Mn) of such polyimide are within the above ranges, it is possible to form a more uniform film more efficiently. The molecular weight (Mw or Mn) and molecular weight distribution (Mw/Mn) of such a polyimide are measured by a gel permeation chromatography (GPC) measuring device (manufactured by Tosoh Corporation, trade name: HLC-8320GPC/ 4 columns: manufactured by Tosoh Corporation, trade name: TSK gel Super AW4000, 3000, 2500, SuperH-RC, solvent: N,N-dimethylacetamide (DMAc)) Data measured using polystyrene conversion to obtain can be done. If it is difficult to measure the molecular weight of such a polyimide, the molecular weight and the like can be estimated based on the viscosity of the polyamic acid used to produce the polyimide, and the polyimide according to the application can be selected. may be used.

In addition, since the polyimide of the present invention can be soluble in solvents, it can be dissolved in an organic solvent and used as a polyimide solution (resin solution: varnish). The organic solvent used for such a polyimide solution is N-methyl-2-pyrrolidone, N, N -dimethylformamide, N,N-dimethylacetamide, γ-butyrolactone, propylene carbonate, tetramethylurea, 1,3-dimethyl-2-imidazolidinone, cyclopentanone, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, γ-butyrolactone and tetramethylurea are more preferred, and N,N-dimethylacetamide and γ-butyrolactone are particularly preferred. In addition, such an organic solvent may be used individually by 1 type or in combination of 2 or more types.

In addition, when the polyimide of the present invention is used as a polyimide solution, it can be suitably used as a coating liquid or the like for producing various processed products. For example, when forming a film, a polyimide film may be formed by applying a polyimide solution onto a substrate to obtain a coating film and then removing the solvent. In such a polyimide solution, the content (dissolution amount) of the polyimide is not particularly limited, but is preferably 1 to 75% by mass, more preferably 10 to 50% by mass.

In addition, the polyimide of the present invention may be used by appropriately containing known components according to its use, such as other polymers, antioxidants, ultraviolet absorbers, hindered amine light stabilizers, nucleating agents, Clarifying agents, inorganic fillers (glass fibers, hollow glass spheres, talc, mica, alumina, titania, silica, etc.), heavy metal deactivators, filler-filled plastic additives, flame retardants, processability improvers, lubricants/water Additional components such as dispersing stabilizers, permanent antistatic agents, toughness improvers, surfactants, carbon fibers, etc. may be further contained and utilized.

The shape of such polyimide is not particularly limited, and for example, it may be in the form of film or powder, or may be in the form of pellets by extrusion molding. As described above, the polyimide of the present invention can be formed into a film shape, extruded into a pellet shape, or formed into various shapes by known methods.

Further, the method for producing the polyimide of the present invention is not particularly limited. For example, when using the compound represented by the general formula (1) as the monomer (A), the tetracarboxylic dianhydride is Except for using the compound represented by the general formula (1), a known method for producing a polyimide by reacting a tetracarboxylic dianhydride and a diamine (for example, described in WO 2011/099518) methods (methods described in International Publication No. 2015/163314, etc.) can be appropriately adopted.

In addition, the method that can be suitably used as a method for producing the polyimide of the present invention is not particularly limited, but for example, the monomer (A) and the monomer (B) are subjected to a polyaddition reaction to produce a polyimide precursor. A body resin (preferably polyamic acid (polyamic acid)) is formed, and then the polyimide precursor resin is subjected to ring-closing condensation (dehydration ring-closing: intramolecular condensation) to imidize the monomer (A) and the monomer (B). (hereinafter sometimes simply referred to as "polyimide production method (I)") can be employed. The method (I) for producing polyimide, which can be suitably used as a method for producing the polyimide of the present invention, will be briefly described below.

In the method (I) for producing such a polyimide, first, the monomer (A) and the monomer (B) are subjected to a polyaddition reaction to form a polyimide precursor resin (preferably polyamic acid), which is then used. It is a method of obtaining polyimide. In addition, the "polyimide precursor resin" referred to herein may be obtained by subjecting the monomer (A) and the monomer (B) to a polyaddition reaction, and the monomer (A) and the monomer (B ) as well as derivatives obtained from the addition polymer. In the following, first, the polyimide precursor resin that is formed when producing polyimide will be described.

Examples of such a polyimide precursor resin include the following general formula (11):

[In the formula (11), Ar represents a residue obtained by removing two amino groups from the diamine compound used ^as the monomer (B); One selected from the group consisting of an alkyl group and an alkylsilyl group having 3 to 9 carbon atoms, wherein one of the bond represented by a and the bond represented by b is represented by *1 The other of the bond represented by a and the bond represented by b binds to the carbon atom represented by * 2, and the bond represented by c and the bond represented by d One of the bonds is attached to the carbon atom represented by * 3, and the other of the bonds represented by c and d is represented by * 4. Binds to a carbon atom. ]
Those having a repeating unit (II) represented by can be mentioned. Incidentally, such a repeating unit (II) is obtained by polyaddition of the tetracarboxylic dianhydride represented by the general formula (1) and/or a derivative thereof and the diamine compound, or by polyaddition After that, it can be obtained by induction. Therefore, the repeating unit (II) is a structure (repeating unit) obtained by polyaddition of the tetracarboxylic dianhydride and/or derivative thereof represented by the general formula (1) and the diamine compound. and its derivatives.

Here, each Y ¹ in formula (11) is independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms (preferably 1 to 3 carbon atoms) and an alkylsilyl group having 3 to 9 carbon atoms. One selected is shown. Such ^Y1 can be changed by appropriately changing the type of substituent and the introduction rate of the substituent by appropriately changing the production conditions. Incidentally, when all such Y ¹ are hydrogen atoms (so-called repeating units of polyamic acid), polyimide can be produced efficiently by dehydration and ring closure. Further, when Y ¹ in the general formula (11) is an alkyl group having 1 to 6 carbon atoms (preferably 1 to 3 carbon atoms), the storage stability of the polyimide precursor resin tends to be more excellent. It is in. The alkyl group having 1 to 6 carbon atoms that can be selected as Y ¹ is more preferably a methyl group or an ethyl group. Further, when Y ¹ in the general formula (11) is an alkylsilyl group having 3 to 9 carbon atoms, the solubility of the polyimide precursor resin tends to be more excellent. As the alkylsilyl group having 3 to 9 carbon atoms that can be selected as Y ¹ , a trimethylsilyl group or a t-butyldimethylsilyl group is more preferable.

Regarding Y ¹ in the formula (11), the introduction rate of groups other than hydrogen atoms (alkyl groups and/or alkylsilyl groups) is not particularly limited, but all repeating units (II) contained in the polyimide precursor resin When at least part of all Y ¹ in the above are alkyl groups and/or alkylsilyl groups, the total amount of Y ¹ in the repeating unit (II) is 25% or more (more preferably 50% or more, still more preferably is 75% or more) is preferably an alkyl group and/or an alkylsilyl group (in this case, Y ¹ other than the alkyl group and/or the alkylsilyl group is a hydrogen atom). When 25% or more of the total amount of ^Y1 is an alkyl group and/or an alkylsilyl group, the storage stability of the polyimide precursor resin tends to be more excellent.

Further, when the polyimide precursor resin has the repeating unit (II), the content of the repeating unit (II) is not particularly limited, but 70 to 70 to all repeating units in the polyimide precursor resin. It is preferably 100 mol %, more preferably 90 to 100 mol %, particularly preferably 100 mol %. By making the content of the repeating unit (II) equal to or higher than the lower limit, it is possible to further reduce the yellowness of the polyimide when the polyimide is produced compared to the case where the content is lower than the lower limit. In addition, such a polyimide precursor resin has a structure (repeating unit) obtained by polyaddition of the tetracarboxylic dianhydride represented by the formula (1) and/or a derivative thereof and the diamine compound. and derivatives thereof, and further having a structure (other repeating unit) obtained by polyaddition of another tetracarboxylic dianhydride and / or a derivative thereof and a diamine compound good.

In the polyimide production method (I), the method for forming the polyimide precursor resin (preferably polyamic acid (polyamic acid)) is not particularly limited, but in the presence of an organic solvent, the monomer (A) and the monomer ( A method of obtaining a polyimide precursor resin by subjecting B) to a polyaddition reaction can be preferably employed. The organic solvent used in such a method includes an organic solvent capable of dissolving both the monomer (A) and the monomer (B) (more preferably, an organic solvent capable of dissolving the polyimide precursor to be formed). ) is preferred. Examples of such organic solvents include N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide, γ-caprolactone (GBL), tetramethylurea (N , N,N′,N′-tetramethylurea (TMU), dimethylsulfoxide, δ-valerolactone and the like. You may use such an organic solvent individually by 1 type or in mixture of 2 or more types.

Moreover, the conditions for the polyaddition reaction of the monomer (A) and the monomer (B) are not particularly limited. Except for using the compound represented by the general formula (1) as the carboxylic dianhydride, a known method for producing a polyamic acid by reacting a tetracarboxylic dianhydride and a diamine (e.g., International Publication No. 2011/099518, the method described in International Publication No. 2015/163314, etc.) can be employed as appropriate. In this way, by using the compound represented by the general formula (1) as the monomer (A) to proceed with the addition polymerization reaction between the tetratetracarboxylic dianhydride and the diamine compound, It is possible to obtain a polyamic acid suitable as a polyimide precursor resin (a polyimide precursor resin having repeating units (II) in which all Y ¹ in formula (11) are hydrogen atoms).

Here, as a production method for producing a polyimide precursor resin containing a repeating unit (II) such that Y ¹ in formula (11) is other than a hydrogen atom, for example, a tetracarboxylic dianhydride Manufactured in the same manner as described in paragraphs [0165] to [0174] of WO 2018/066522, except that the tetracarboxylic dianhydride represented by the general formula (1) is used. Any suitable method may be employed.

Further, in the method (I) for producing a polyimide, after forming a polyimide precursor resin, the polyimide precursor resin is imidized by ring-closing condensation (dehydration ring-closing: intramolecular condensation) to obtain a polyimide.

The method (conditions, etc.) for imidizing the polyimide precursor resin (preferably polyamic acid) by ring-closing condensation is not particularly limited, and a known imidization method (e.g., International Publication No. 2011/099518). The method (conditions) employed in the imidization method, etc.) can be employed as appropriate.

Further, in the method (I) for producing a polyimide, the monomer (A) and the monomer (B) are heated and reacted in an organic solvent in the presence of a reaction accelerator to form the polyimide precursor resin. , and subsequent ring-closing condensation (imidization) are preferably allowed to proceed simultaneously as a series of reactions to form the polyimide. As a result, the formation of the intermediate polyimide precursor resin (preferably polyamic acid) and the subsequent formation of the polyimide (imidation) can proceed simultaneously to efficiently produce the polyimide. Moreover, it is also possible to obtain polyimide dissolved in an organic solvent, and it is also possible to efficiently obtain a polyimide solution (polyimide varnish) composed of an organic solvent and polyimide. When polyimide is formed by such a method, high-molecular-weight polyimide is efficiently formed, and the obtained polyimide tends to have higher heat resistance. Therefore, the polyimide of the present invention is preferably a cured product of the polyimide varnish obtained by the above method, from the viewpoint that the heat resistance can be further improved. In addition, when polyimide varnish is prepared in this way, it is possible to prepare polyimide in the form of a film by coating it on a substrate and curing it, so that various shapes of polyimide can be produced more efficiently. It is also possible to

Further, the reaction accelerator used when heating the monomer (A) and the monomer (B) in an organic solvent in the presence of the reaction accelerator is not particularly limited, but reactivity, availability, practicality from the viewpoint of , triethylamine, diisopropylethylamine, N-methylpiperidine and pyridine are preferred, triethylamine, pyridine and N-methylpiperidine are more preferred, and triethylamine and N-methylpiperidine are still more preferred. Such reaction accelerators may be used singly or in combination of two or more. The heating temperature for heating the monomers (A) and (B) in an organic solvent in the presence of a reaction accelerator is not particularly limited, but is preferably 150 to 200°C. By setting the heating temperature within the above range, polyimide can be produced more efficiently.

EXAMPLES The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[Regarding the monomers used in Examples etc.]
First, the monomers (tetracarboxylic dianhydride and diamine compound) used in each example will be briefly described.

<Tetracarboxylic dianhydride>
The tetracarboxylic dianhydrides used in each example are represented by the following abbreviations (BpDA, BzDA).
• BpDA: a compound represented by the above formula (1) • BzDA: a compound represented by the above formula (3).

<Diamine compound>
The diamine compounds used in each example are represented by the following abbreviations (3,4'-DDE, 4,4'-DDE, DABAN, etc.). The relationship between the abbreviations and chemical formulas of each diamine compound is shown below.

The compound name of BAPP is 2,2-bis[4-(4-aminophenoxy)phenyl]propane, the compound name of TPE-R is 1,3-bis(4-aminophenoxy)benzene, and 3 ,4'-DDE, 4,4'-DDE, DABAN, TFMB, and Bis-AP-AF are as described above. BAPP and TPE-R were used as components for comparison.

(Example 1)
<Varnish preparation process>
First, 1.00 g (5.00 mmol) of 4,4′-DDE as a diamine compound and 2.41 g (5.00 mmol) of BpDA as a tetracarboxylic dianhydride were introduced into a 50 mL flask. Next, in the flask, 6.8 g of N,N-dimethylacetamide (DMAc) as an organic solvent, 6.8 g of γ-butyrolactone (GBL) as an organic solvent, and triethylamine ( A mixed solution was obtained by introducing 0.025 g (0.25 mmol) of TEA). Next, the mixed solution thus obtained is stirred under the conditions of a temperature of 180° C. and a time of 3 hours under a nitrogen atmosphere while being heated to form a viscous, uniform pale yellow reaction solution, which is a polyimide varnish. (PI varnish) was obtained.

<Film preparation process>
Next, the PI varnish was applied to a glass substrate having a length of 76 mm and a width of 52 mm using a spin coater to form a coating film of the PI varnish on the glass substrate. Then, the glass substrate on which the coating film was formed was set in a vacuum hot chamber, and the coating film was dried by holding at 70 ° C. for 30 minutes under reduced pressure conditions (drying before baking, drying conditions: 70 ° C. , 30 minutes). After that, the glass substrate on which the dried coating film was formed was set in an inert oven and purged with nitrogen. Next, the temperature of the inert oven after the nitrogen purge is raised until it reaches the baking temperature (350°C), held at 350°C (firing temperature) for 1 hour, and then allowed to cool to room temperature (about 25°C). Then, the inert oven was operated to form (heat cure) polyimide on the glass substrate to obtain a glass substrate coated with a polyimide film (baking conditions: 350° C., 1 hour). Then, the polyimide film was peeled off from the glass substrate to obtain a polyimide film (film-like polyimide). The obtained film was visually confirmed to be colorless and transparent.

(Examples 2-5 and Comparative Examples 1-6)
First, the type and amount of the tetracarboxylic dianhydride used, the type and amount of the diamine compound used, the type and amount of the organic solvent used, and the heating conditions of the mixture were changed to the conditions shown in Table 1. Each PI varnish was prepared in the same manner as <varnish preparation step> employed in Example 1, except that

Next, in Examples 2 to 5, Comparative Examples 2 and 4 to 6, the obtained PI varnish was used, and the firing conditions (firing temperature and holding time) were set to the conditions shown in Table 1. A film made of polyimide was obtained in the same manner as <Film preparation step> employed in Example 1, except that the steps were changed. On the other hand, in Comparative Examples 1 and 3, the obtained PI varnish was used to form a coating film of the PI varnish on a glass substrate, and then the glass plate having the coating film formed thereon was put into an inert oven. Then, the coating film is dried by raising the temperature to 60 ° C. under a nitrogen stream and holding it at 60 ° C. for a holding time of 4 hours (Comparative Example 1) or 3 hours (Comparative Example 2) ( drying before firing), then the temperature of the inert oven is raised to the firing temperature (250°C), held at 250°C (firing temperature) for 1 hour, and then the inert oven is allowed to cool to room temperature. In the same manner as the <film preparation step> employed in Example 1, except that polyimide was formed (heat cured) on the glass substrate to obtain a glass substrate coated with a film made of polyimide. , a polyimide film (film-like polyimide) was obtained. All the films obtained in Examples 2 to 5 and Comparative Examples 1 to 6 were colorless and transparent when visually confirmed.

[Evaluation of properties of polyimides obtained in Examples 1 to 5 and Comparative Examples 1 to 6]
<Measurement of weight loss temperature (Td1%, Td5%)>
5% weight loss temperature (unit: ° C.) and 1% weight loss temperature (unit: ° C.) are obtained as follows using the polyimide films obtained in Examples 1 to 5 and Comparative Examples 1 to 4. rice field. That is, first, a sample of 2 to 10 mg is prepared from the polyimide film obtained in each example, etc., and the sample is placed in an aluminum sample pan, and a thermogravimetric analyzer (SII Nanotechnology Co., Ltd.) is used as a measuring device. Using the company's product name "TG/DTA7200"), the sample was heated from room temperature to 200°C under a nitrogen gas atmosphere at a heating rate of 10°C/min, and held at 200°C for 1 hour. Then, the measured value of the weight of the sample at this point (immediately after holding at 200° C. for 1 hour) was used as the reference value of the weight of the sample (0% reduction: zero point) for measuring the weight loss temperature. After that, the scanning temperature was set from 200° C. to 550° C., and the sample was heated from 200° C. at a heating rate of 10° C./min. It was measured as the temperature of decrease (Td1%), and the temperature at which the weight of the sample decreased by 5% from the reference value was measured as the temperature of 5% weight decrease (Td5%). Table 2 shows the results obtained.

<Measurement of glass transition temperature (Tg)>
The glass transition temperature (unit: ° C.) is measured by cutting out a film having a size of 20 mm in length and 5 mm in width from the polyimide film obtained in each example etc. (The thickness of such a sample is obtained in each example etc. Using a thermomechanical analyzer (trade name "TMA8311" manufactured by Rigaku) as a measuring device, under a nitrogen atmosphere, tensile mode (49 mN), temperature increase rate 5 ° C./min. The TMA curve is obtained by measuring under the conditions of , and the curve before and after the inflection point of the TMA curve due to the glass transition is extrapolated to obtain the resin constituting the film obtained in each example etc. The value of the glass transition temperature (Tg) (unit: ° C.) was determined. Table 2 shows the results obtained.

<Method for measuring dielectric constant (Dk) and dielectric loss tangent (Df)>
The values of dielectric constant (Dk) and dielectric loss tangent (Df) were measured for the polyimides (films) obtained in Examples 1 and 2 and the polyimides (films) obtained in Comparative Examples 1 and 2. . For such measurements, specimens of 1.5 mm width and 70 to 80 mm length were cut out from these polyimides (films), and the cavity resonator perturbation method (IEC 62810 ) was adopted and measured as follows. That is, the dielectric constant (Dk) and dielectric loss tangent (Df) values are measured by heating the test piece (width: 1.5 mm, length: 70 to 80 mm) prepared as described above at 23°C. After standing for 24 hours in an environment of 50% relative humidity, the test was performed in a laboratory controlled to 23° C. and 50% relative humidity. In addition, as a measuring device, “PNA Network Analyzer N522B” manufactured by Keysight Technologies, Inc. and “CP531 for Cavity Resonator 10 GHz” manufactured by Kanto Denshi Applied Development Co., Ltd. were used. Also, in the measurement, the test piece was set in the cavity resonator of the measuring apparatus, and the frequency was set to 10 GHz, and the dielectric constant (Dk) and the dielectric dissipation factor (Df) were measured. Then, such actual values were measured twice, and their average values were obtained to obtain values of dielectric constant (Dk) and dielectric loss tangent (Df). Thus, the values of the dielectric constant (Dk) and the dielectric loss tangent (Df) were the average values of the actual measurements obtained by two measurements. Table 2 shows the results obtained.

In the results shown in Table 2, first, in order to confirm the difference in effect due to the difference in tetracarboxylic dianhydride, Examples 1 to 5 using BpDA as the tetracarboxylic dianhydride and tetracarboxylic dianhydride When comparing the same diamine compounds with Comparative Examples 1 to 4 using BzDA as a When comparing Example 3 and comparing Example 4 and Comparative Example 4, respectively, Tg, Td1%, and Td5% are all higher when BpDA is used as the tetracarboxylic dianhydride. was From these results, when BpDA is used as the tetracarboxylic dianhydride, Tg and weight loss temperature (Td1%, Td5%) are higher than when BzDA is used as the tetracarboxylic dianhydride. It was confirmed that the standard was obtained, and it was found that the heat resistance was of a higher level. The reason why the heat resistance is higher when BpDA is used as the tetracarboxylic dianhydride than when BzDA is used is not necessarily clear, but when BpDA is used, the structure As a result, a biphenyl skeleton is introduced into the polymer chain of the obtained polyimide, so that the rigidity of the obtained polyimide molecule is higher than when using BzDA, which introduces a phenyl skeleton into the polymer chain. The inventors of the present invention speculate that the molecular mobility of the polymer molecules can be further suppressed and the heat resistance can be further improved.

In addition, as is clear from the results shown in Table 2, when comparing Examples 1 and 2 using BpDA and Comparative Examples 1 and 2 using BzDA, the same diamine compound was compared (Example 1 and When comparing Comparative Example 1 and comparing Example 2 and Comparative Example 2, respectively), the dielectric constant (Dk) and the dielectric loss tangent (Df) are lower when BpDA is used as the tetracarboxylic dianhydride. was valued. From these results, when BpDA is used as the tetracarboxylic dianhydride, the dielectric constant (Dk) and dielectric loss tangent (Df) can be made lower than when BzDA is used. was also confirmed. The reason why the dielectric constant (Dk) and dielectric loss tangent (Df) are lower when BpDA is used as the tetracarboxylic dianhydride than when BzDA is used is not necessarily clear, but BpDA is used. In the case of using BzDA, a biphenyl skeleton is introduced into the polymer chain due to its structure. It is possible to reduce the concentration of the imide group of the present invention, which reduces the water absorption and allows the dielectric constant (Dk) and dielectric loss tangent (Df) to be lower values. They speculate.

Next, in order to confirm the difference in effect due to the difference in the type of diamine compound, when BpDA was used as the tetracarboxylic dianhydride (Examples 1 to 5 and Comparative Examples 5 to 6), comparison was made. When the types of diamine compounds to be combined are 3,4'-DDE, 4,4'-DDE, DABAN, TFMB, and Bis-AP-AF (Examples 1 to 5), the Tg of the resulting polyimide is 300 ° C. or higher, whereas when other diamine compounds were used (Comparative Examples 5 and 6), the Tg was less than 300 °C. From these results, by combining BpDA with a specific diamine compound such as that used in Examples 1 to 5, it is possible to increase the Tg of the resulting polyimide to a higher level. It has been confirmed that it is possible to achieve a higher level of heat resistance based on at least Tg.

As described above, according to the present invention, it is possible to provide a polyimide that can have a higher level of heat resistance. As described above, the polyimide of the present invention is particularly excellent in heat resistance, and therefore, for example, polyimide for flexible wiring substrates, polyimide for heat-resistant insulating tape, polyimide for electric wire enamel, polyimide for protective coating of semiconductors (photosensitive polyimide ), polyimide for liquid crystal alignment films, polyimide for transparent electrode substrates (organic EL, solar cells, electronic paper), polyimide for seamless belts of copiers (so-called polyimide for transfer belts), various gas barrier film substrate materials polyimide, polyimide for interlayer insulating films, polyimide for sensor substrates, and the like.

Claims (2)

Formula (1) below:

A monomer (A) containing a tetracarboxylic dianhydride and/or a derivative thereof represented by
3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 4 ,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diaminobenzanilide, 2,2'-bis(trifluoromethyl)benzidine and 2,2-bis(3-amino-4-hydroxy a monomer (B) which is at least one diamine compound selected from the group consisting of phenyl)hexafluoropropane;
A polyimide characterized by being a polymer of The monomer (B) is 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzanilide, 2,2'-bis(trifluoromethyl)benzidine, and 2,2 The polyimide according to claim 1, which is at least one diamine compound selected from the group consisting of -bis(3-amino-4-hydroxyphenyl)hexafluoropropane.