Polyimide, molded body, and film

Abstract

The present invention relates to a polyimide having a diamine component and a tetracarboxylic dianhydride component. The polyimide may be a polyamide-imide having an amide structural unit formed by bonding of the diamine component and a polybasic acid component. The polyimide contains a diamine represented by general formula (X1) as the diamine component and contains, as the tetracarboxylic dianhydride component, at least one tetracarboxylic dianhydride selected from the group consisting of a tetracarboxylic dianhydride having an ether bond, a tetracarboxylic dianhydride having a cardo structure, and a bis(trimellitic anhydride) ester. In general formula (X1), n is an integer of 1-5, and R1 to R8 are each independently hydrogen, an alkyl chain, a halogen, or an alkoxy group.

Description

Polyimide, molding and film

[0001] The present invention relates to polyimides and molded articles such as films.

[0002] There is a demand for thinner, lighter, and more flexible electronic devices, such as display devices (e.g., liquid crystal displays, organic electroluminescence displays, and electronic paper), solar cells, and touch panels. By replacing the glass materials used in these devices with film materials, these devices can be made more flexible, thinner, and lighter. Transparent polyimide films have been developed as glass replacement materials and are used for display substrates, cover films, and the like.

[0003] A method for producing a highly transparent polyimide film has been proposed that uses a polyimide resin that is soluble in organic solvents and does not require high-temperature imidization after film formation. To achieve a balance between transparency and mechanical properties, such soluble polyimides use fluorine-containing compounds as the diamine and / or tetracarboxylic dianhydride monomers. Numerous soluble polyimides have been proposed that use fluoroalkyl-substituted benzidines, such as 2,2'-bis(trifluoromethyl)benzidine (TFMB), as the diamine (see, for example, Patent Document 1). Patent Document 2 proposes the use of a polyamideimide, which uses TFMB as the diamine and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), as a display material.

[0004] International Publication No. 2020 / 004236 International Publication No. 2013 / 048126

[0005] In recent years, the environmental persistence of organic fluorine compounds (PFAS) has become a problem. In general, the carbon-fluorine bond contained in organic fluorine compounds has high bond energy and is difficult to decompose in the environment. In particular, the structure in which a trifluoromethyl group is bonded to a carbon atom (-C-CF ３ ), or a structure in which carbon atoms are bonded to both ends of a difluoromethylene group (—C—CF ２Organic fluorine compounds containing fluorine atoms (C) have low decomposition properties in the environment and have been reported to have adverse effects on the human body.

[0006] In view of the above problems, an object of the present invention is to provide a polyimide that is environmentally safe, soluble in organic solvents, and highly transparent, and a molded article such as a film containing the polyimide.

[0007] The polyimide of the present invention contains, as the diamine component, a diamine (specific diamine) represented by general formula (X1), and, as the tetracarboxylic acid dianhydride component, one or more tetracarboxylic acid dianhydrides (specific acid dianhydrides) selected from the group consisting of tetracarboxylic acid dianhydrides having an ether bond, tetracarboxylic acid dianhydrides having a cardo structure, and bis(trimellitic anhydride) esters.

[0008]

[0009] In general formula (X1), n ​​is an integer of 1 to 5, and R １ ~R ８ are each independently hydrogen, an alkyl chain, a halogen, or an alkoxy group.

[0010] Preferred examples of the specific diamine include 1,4-bis(4-aminophenoxy)tetrafluorobenzene, 1,4-bis(4-amino-3-methylphenoxy)tetrafluorobenzene, 1,4-bis(4-amino-3,5-dimethylphenoxy)tetrafluorobenzene, 2,2',3,3',5,5',6,6'-octafluoro-4,4'-bis(4-aminophenoxy)-1,1'biphenyl, 2,2',3,3',5,5',6,6'-octafluoro-4,4'-bis(4-amino-3-methylphenoxy)-1,1'biphenyl, and 2,2',3,3',5,5',6,6'-octafluoro-4,4'-bis(4-amino-3,5-dimethylphenoxy)-1,1'biphenyl.

[0011] Preferred examples of the specific acid dianhydride include 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride, 5,5'-(9H-fluoren-9-ylidenebis(2-methyl-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylate], spiro[11H-difuro[3,4-b:3',4'-i]xanthene-11,9' -[9H]fluorene]-1,3,7,9-tetraone, 5,5'-spiro[9H-fluorene-9,9'-[9H]xanthene]-3',6'-diylbis(1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylate), 1,4-phenylenebis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate), and 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diylbis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate).

[0012] The polyimide may contain a diamine other than the specific diamine as the diamine component, and may contain a tetracarboxylic dianhydride other than the specific acid dianhydride as the tetracarboxylic dianhydride component.

[0013] The amount of CF on the carbon atom of the aromatic ring relative to the total amount of diamine components of the polyimide ３ - or -C(CF ３ ) ２ The amount of diamine having a structure in which - is directly bonded, and -CF ２ (CF ２ ) ｍ CF ２ The amount of each of the diamines having - (m is an integer of 1 or more) is preferably less than 0.5 mol %. ３ - or -C(CF ３ ) ２ the amount of tetracarboxylic dianhydride having a structure in which - is directly bonded, and -CF ２ (CF ２ )ｌ CF ２ The amount of each tetracarboxylic dianhydride having - (l is an integer of 1 or more) is preferably less than 0.5 mol %.

[0014] The polyimide is preferably soluble in dimethylformamide at 23°C.

[0015] The polyimide may be a polyamideimide containing a polybasic acid component in addition to a diamine component and a tetracarboxylic dianhydride, and having an amide structural unit formed by bonding between the diamine component and the polybasic acid component.

[0016] Polyamideimide is a compound in which the carbon atoms of the aromatic ring are bonded with CF ３ - or -C(CF ３ ) ２ The amount of polybasic acid having a structure in which - is directly bonded, and -CF ２ (CF ２ ) ｊ CF ２ The amount of each of the polybasic acids having - (j is an integer of 1 or more) is preferably less than 0.5 mol %.

[0017] The polyimide of the present invention, which contains a specific diamine as a diamine component and a specific acid dianhydride as a tetracarboxylic dianhydride component, has excellent solubility in organic solvents and transparency. Furthermore, since the specific diamine has lower environmental persistence than organic fluorine compounds such as fluoroalkyl-substituted benzidine, the polyimide of the present invention has excellent environmental safety.

[0018] [Polyimide Composition] Polyimide is a polymer having a structural unit represented by general formula (I). In addition to the imide structure of general formula (I), the polyimide may contain an amide structural unit represented by general formula (II) and / or an amide-imide structural unit represented by general formula (III). A polyimide containing an amide structural unit in addition to an imide structural unit is also called a polyamideimide.

[0019]

[0020] In general formulas (I) to (III), X is a tetravalent organic group, Y and Z are divalent organic groups, and W is a trivalent organic group. Y is a diamine residue, which is an organic group obtained by removing two amino groups from a diamine represented by the following general formula (V). X is a tetracarboxylic dianhydride (hereinafter sometimes referred to as "acid dianhydride") residue, which is an organic group obtained by removing two carboxy anhydride groups from a tetracarboxylic dianhydride represented by the following general formula (IV). Z is a dicarboxylic acid residue, which is an organic group obtained by removing two carboxy groups from a dicarboxylic acid represented by the following general formula (VI). W is a tricarboxylic acid anhydride residue, which is an organic group obtained by removing a carboxy anhydride group and a carboxy group from a tricarboxylic acid anhydride represented by the following general formula (VII).

[0021]

[0022] In other words, the polyimide contains a diamine-derived structure represented by the following general formula (Va) and a tetracarboxylic dianhydride-derived structure represented by the following general formula (IVa), and the diamine-derived structure (Va) and the tetracarboxylic dianhydride-derived structure (IVa) form an imide bond to form an imide structural unit represented by general formula (I). The polyamideimide contains, in addition to the diamine-derived structure and the tetracarboxylic dianhydride-derived structure, one or more structures selected from the group consisting of a dicarboxylic acid-derived structure represented by the following general formula (VIa) and a tricarboxylic acid anhydride-derived structure represented by the following general formula (VIIa). In the polyamideimide, the diamine-derived structure (Va) and the dicarboxylic acid-derived structure (VIa) form an amide bond to form an amide structural unit represented by general formula (II), and the carboxy anhydride group portion and carboxy group portion of the tricarboxylic acid anhydride-derived structure (VIIa) form an imide bond and an amide bond, respectively, with the diamine-derived structure (Va), to form an amide-imide structural unit represented by general formula (III).

[0023]

[0024] In general formula (I), a polyimide in which the diamine residue Y contains an amide bond is a polyamideimide, and polyamideimide can be considered a type of polyimide. Hereinafter, unless otherwise specified, the term "polyimide" includes "polyamideimide." A polyimide may contain multiple types of diamine residues Y, multiple types of tetracarboxylic dianhydride residues X, and may further contain one or more types of dicarboxylic acid residues Z and one or more types of tricarboxylic acid anhydride residues W.

[0025] As will be described in detail later, polyimides are generally obtained by synthesizing polyamic acid using diamines and tetracarboxylic dianhydrides as monomers and then cyclizing the amide acid at the bond between the tetracarboxylic acid and the diamine. Polyimides can also be synthesized by condensation of tetracarboxylic dianhydrides with diisocyanates through decarboxylation, but regardless of the synthesis method, the resulting polyimide has an acid dianhydride-derived structure (tetracarboxylic dianhydride residue) X obtained by removing four carboxy groups from the tetracarboxylic dianhydride, and a diamine-derived structure (diamine residue) Y obtained by removing two amino groups from the diamine. Therefore, even when the starting materials used in polyimide synthesis are not tetracarboxylic dianhydrides or diamines, the structure corresponding to the tetracarboxylic dianhydride residue contained in the polyimide is referred to as the "acid dianhydride component," and the structure corresponding to the diamine residue is referred to as the "diamine component."

[0026] In the synthesis of polyamideimide, in addition to diamine and tetracarboxylic dianhydride, polybasic acid derivatives such as dicarboxylic acid dichloride and tricarboxylic acid anhydride chloride are used, and the resulting polyamideimide has a structure Z (dicarboxylic acid residue) obtained by removing two carboxy groups from a dicarboxylic acid, or a structure W (tricarboxylic acid residue) obtained by removing three carboxy groups from a tricarboxylic acid. Therefore, even when the starting material used in the synthesis of polyamideimide is a polybasic acid derivative, the structure corresponding to the polybasic acid residue is expressed as a "polybasic acid component."

[0027] The diamine component and tetracarboxylic dianhydride component as monomer units constituting the polyimide, and the polybasic acid component when the polyimide is a polyamideimide, will be described below with examples.

[0028] <Diamine> (Specific Diamine) The polyimide of the present invention contains a diamine represented by general formula (X1) as a diamine component. In general formula (X1), n ​​is an integer of 1 to 5, and R １ ~R ８ are each independently hydrogen, an alkyl chain, a halogen, or an alkoxy group.

[0029]

[0030] Hereinafter, the diamine represented by general formula (X1) may be referred to as a "specific diamine." The specific diamine has a structure in which a fluorine atom is directly bonded to a carbon atom of an aromatic ring, and is more environmentally degradable than a compound in which a fluoroalkyl group such as a trifluoromethyl group is bonded to a carbon atom of an aromatic ring. Therefore, polyimides using the specific diamine as the diamine component tend to be more degradable and less likely to persist in the environment than conventional transparent polyimides using a fluoroalkyl-substituted benzidine as the diamine component.

[0031] Specific examples of the specific diamine include 1,4-bis(4-aminophenoxy)tetrafluorobenzene, 1,4-bis(4-amino-3-methylphenoxy)tetrafluorobenzene, 1,4-bis(4-amino-3,5-dimethylphenoxy)tetrafluorobenzene, 2,2',3,3',5,5',6,6'-octafluoro-4,4'-bis(4-aminophenoxy)-1,1'biphenyl, 2,2',3,3',5,5',6,6'-octafluoro-4,4'-bis(4-amino-3-methylphenoxy)-1,1'biphenyl, 2,2',3,3',5,5',6,6'-octafluoro-4,4'-bis(4-amino-3,5-dimethylphenoxy)-1,1'biphenyl, and the like.

[0032] The amount of the specific diamine relative to the total amount of the diamine components is preferably 10 mol% or more, more preferably 30 mol% or more, and even more preferably 50 mol% or more, and may be 60 mol% or more, 70 mol% or more, 80 mol% or more, or 90 mol% or more, or may be 100 mol%. The higher the ratio of the specific diamine, the more suppressed the coloring and the more improved the mechanical strength of the film, such as pencil hardness, elastic modulus, breaking strength, and breaking elongation.

[0033] (Diamines other than the specific diamines) The polyimide may contain diamines other than the specific diamines as the diamine component. ３ and -C-CF ２ Those which do not contain —C— are preferred, and those which do not contain a fluorine atom are particularly preferred.

[0034] Examples of diamines not containing fluorine atoms include 2,2'-dimethylbenzidine, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, and 4,4'-diaminodiphenyl sulfone. 9,9-bis(4-aminophenyl)fluorene, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, 9,9-bis(4-amino-3-methylphenyl)fluorene, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2-di(3-aminophenyl)propane, 2,2-di(4-aminophenyl)propane, 2-(3-aminophenyl)-2 -(4-aminophenyl)propane, 1,1-di(3-aminophenyl)-1-phenylethane, 1,1-di(4-aminophenyl)-1-phenylethane, 1-(3-aminophenyl)-1-(4-aminophenyl)-1-phenylethane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminobenzoyl)benzene, 1,3-bis(4-aminobenzoyl)benzene , 1,4-bis(3-aminobenzoyl)benzene, 1,4-bis(4-aminobenzoyl)benzene, 1,3-bis(3-amino-α,α-dimethylbenzyl)benzene, 1,3-bis(4-amino-α,α-dimethylbenzyl)benzene, 1,4-bis(3-amino-α,α-dimethylbenzyl)benzene, 1,4-bis(4-amino-α,α-dimethylbenzyl)benzene, 2,6-bis(3-aminophenoxy)benzonitrile, 2,6-bis(3-aminophenoxy)pyridine, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, 2,2-bis[4-( 1,3-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene, 1,3-bis[4-(4-aminophenoxy)benzoyl]benzene, 1,4-bis[4-(3-aminophenoxy)benzoyl]benzene, 1,4-bis[4-(4-aminophenoxy)benzoyl]benzene, 1,3-bis[4-(3-aminophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)-α,α-dimethyl benzyl]benzene, 1,4-bis[4-(3-aminophenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(4-aminophenoxy)-α,α-dimethylbenzyl]benzene, 4,4'-bis[4-(4-aminophenoxy)benzoyl]diphenyl ether, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzophenone, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]diphenyl sulfone, 4,4'-bis[4-(4-aminophenoxy)phenoxy]diphenyl sulfone, 3,3'-diamino-4,4'-diphenoxybenzophenone, 3,3'-diamino-4,4'-dibiphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 3,3'-diamino-4-biphenoxybenzophenone, 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane, 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane, 1,3-bis(3-aminopropyl)tetramethyldisiloxane, 1,3-bis(4-aminobutyl)tetramethyldisiloxane, α,ω-bis(3-aminopropyl)polydimethylsiloxane, α,ω-bis(3-aminobutyl)polydimethylsiloxane, bis(aminomethyl)ether, bis(2-aminoethyl)ether, bis(3-aminopropyl)ether, bis(2-aminomethoxy)ethyl]ether, bis[2-(2-aminoethoxy)ethyl]ether, bis[2-(3-aminopropoxy)ethyl]ether, 1,2-bis(aminomethoxy)ethane, 1,2-bis(2-aminoethoxy)ethane, 1,2-bis[2-(aminomethoxy)ethoxy]ethane, 1,2-bis[2-(2-aminoethoxy)ethoxy]ethane, ethylene glycol bis(3-aminopropyl)ether, diethylene glycol bis(3-aminopropyl)ether, triethylene glycol bis(3-aminopropyl) Ether, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane Examples of suitable cyclohexanes include cyclohexane, trans-1,4-diaminocyclohexane, 1,2-di(2-aminoethyl)cyclohexane, 1,3-di(2-aminoethyl)cyclohexane, 1,4-di(2-aminoethyl)cyclohexane, bis(4-aminocyclohexyl)methane, isophoronediamine, 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, and 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane.

[0035] The use of diaminodiphenyl sulfone as the diamine in addition to the specific diamine may improve the solubility in solvents and transparency of the polyamideimide. Among diaminodiphenyl sulfones, 3,3'-diaminodiphenyl sulfone (3,3'-DDS) and 4,4'-diaminodiphenyl sulfone (4,4'-DDS) are preferred, and these may be used in combination.

[0036] When diaminodiphenyl sulfone is used in addition to the specific diamine, the amount of diaminodiphenyl sulfone relative to the total amount of the diamine components may be 1 to 40 mol %, 3 to 30 mol %, or 5 to 25 mol %.

[0037] The use of a diamine having a fluorene structure in addition to the specific diamine as the diamine may improve the solubility in solvents, transparency, mechanical strength, and heat resistance of the polyamideimide. Preferred fluorene-containing diamines are 9,9-bis(4-aminophenyl)fluorene, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, 9,9-bis(3-amino-4-hydroxyphenyl)fluorene, and 9,9-bis(4-amino-3-methylphenyl)fluorene, and these may be used in combination.

[0038] When a diamine having a fluorene structure is used in addition to the specific diamine, the amount of the diamine having a fluorene structure relative to the total amount of the diamine components may be 1 to 80 mol %, 3 to 60 mol %, or 5 to 30 mol %.

[0039] The total amount of the specific diamine, diaminodiphenyl sulfone, and diamine having a fluorene structure relative to the total amount of diamine components in the polyimide is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and may be 95 mol% or more, 99 mol% or more, or even 100 mol%.

[0040] The polyimide may contain a fluorine atom-containing diamine other than the specific diamine as a diamine component, but from the viewpoint of environmental safety of the polyimide, the amount of the fluorine atom-containing diamine other than the specific diamine relative to the total amount of the diamine components of the polyimide is preferably 30 mol % or less, more preferably 20 mol % or less, even more preferably 10 mol % or less, and may be 5 mol % or less, 1 mol % or less, or 0.5 mol % or less. The polyimide may not contain a fluorine atom-containing diamine other than the specific diamine as a diamine component.

[0041] Among fluorine atom-containing diamines, the structure in which a trifluoromethyl group is bonded to a carbon atom (—C—CF３ ) and / or a structure in which carbon atoms are bonded to both ends of a difluoromethylene group (—C—CF ２ In order to improve the transparency and solubility of polyimides in solvents, general soluble polyimides contain CF4 as a diamine component on the carbon atom of the aromatic ring. ３ - or -C(CF ３ ) ２ However, from the viewpoint of environmental safety of the polyimide, it is preferable that the polyimide is substantially free of these diamines.

[0042] The amount of CF on the carbon atom of the aromatic ring relative to the total amount of diamine components of the polyimide ３ - or -C(CF ３ ) ２ The amount of diamine to which - is directly bonded is preferably less than 0.5 mol %, and may be 0.3 mol % or less, 0.1 mol % or less, or 0.05 mol % or less, or may be 0. ２ (CF ２ ) ｍ CF ２ The amount of diamine having - (m is an integer of 1 or more) is preferably less than 0.5 mol %, and may be 0.3 mol % or less, 0.1 mol % or less, or 0.05 mol % or less, or may be 0.

[0043] <Tetracarboxylic acid dianhydride> (Specific acid dianhydride) The polyimide of the present invention contains, as an acid dianhydride component, one or more acid dianhydrides selected from the group consisting of acid dianhydrides having an ether bond, acid dianhydrides having a cardo structure, and bis(trimellitic anhydride) esters. Hereinafter, these acid dianhydrides will be referred to as "specific acid dianhydrides."

[0044] Examples of acid dianhydrides having an ether bond include those in which two phthalic anhydrides are bonded via an ether bond (—O—) or a functional group containing an ether bond. Examples of acid dianhydrides in which two phthalic anhydrides are bonded via an ether bond include 3,4′-oxydiphthalic anhydride (a-ODPA) and 4,4′-oxydiphthalic anhydride (s-ODPA).

[0045] An example of a functional group containing an ether bond is a bisphenol derivative structure. An example of an acid dianhydride in which two phthalic anhydrides are bonded via a bisphenol derivative structure is a compound represented by the following general formula (1) (bisphenol-type tetracarboxylic dianhydride):

[0046]

[0047] In general formula (1), A is any divalent organic group, and at both ends of A, a phenyl group is bonded to a carbon atom of A. p is 1 or 2. １ａ , R １ｂ , R ２ａ and R ２ｂ are each independently an arbitrary substituent, and from the viewpoint of the solubility of the polyimide, are preferably an alkyl group having 1 to 10 carbon atoms, a phenyl group, an alkoxy group, or a halogen. m1 and m2 are each independently an integer of 0 to 3, and n1 and n2 are each independently an integer of 0 to 4.

[0048] Examples of the divalent organic group A include the following (a), (b), and (c). ３ａ and R ３ｂ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a phenyl group. ４ is an alkyl group having 1 to 10 carbon atoms, and k is an integer of 0 to 10. When k is 2 or more, multiple R ４ may be the same or different.

[0049]

[0050] From the viewpoint of the solubility of the polyimide, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (BPADA) is particularly preferred as the bisphenol tetracarboxylic dianhydride.

[0051] Acid dianhydrides having a cardo structure are compounds in which four aromatic rings are bonded to the carbon atom at the 9th position of fluorene, and specific examples thereof include 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride (BPF-PA), N,N'-(9H-fluoren-9-ylidene-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxamide] (FDA-ATA), 5,5'-(9H -fluoren-9-ylidenebis(2-methyl-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylate] (TBIS-MPN), 5,5'-spiro[9H-fluorene-9,9'-[9H]xanthene]-3',6'-diylbis(1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylate (TBIS-RXN), spiro[fluorene-9,9'xanthene]-2',3',6',7'-tetracarboxylic dianhydride (SFDA), and the like.

[0052] From the viewpoint of the solubility of polyimide, BPAF, BPF-PPA, and TBIS-MPN are preferred as the acid dianhydride having a cardo structure, and among these, BPAF and TBIS-MPN are particularly preferred.

[0053] The bis(trimellitic anhydride) ester is represented by the following general formula (2).

[0054]

[0055] In the general formula (2), B is any divalent organic group, and at both ends of B, a carboxy group and a carbon atom of B are bonded. The divalent organic group B is difluoromethylene (-CF ２ Specific examples of the divalent organic group B include the following (i) to (viii):

[0056]

[0057] In formulas (i) and (ii), R １ , R ２ａ and R ２ｂ are each independently an alkyl group having 1 to 4 carbon atoms, an alkoxy group, or a halogen atom, and m, n1, and n2 are each independently an integer of 0 to 4. In formulas (iii), (iv), and (v), R ３ａ and R ３ｂ are each independently an arbitrary substituent, and from the viewpoint of the solubility of the polyamideimide, an alkyl group having 1 to 10 carbon atoms or a phenyl group is preferred. k1 and k2 are each independently an integer of 0 to 4. R ４ is an alkyl group, an alkoxy group, or a halogen; and j is an integer of 0 to 10.

[0058] The bis(trimellitic anhydride) ester is preferably an aromatic ester, and among the above (i) to (viii), (i) to (v) are preferred as B in the general formula (2), with (i) to (iv) being preferred, and (i) and (ii) being particularly preferred.

[0059] When B is a group represented by general formula (i), from the viewpoint of the mechanical properties of a molded product such as a film, the bis(trimellitic anhydride) ester of general formula (2) is preferably 1,4-phenylenebis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (TMHQ) represented by the following formula (2-1):

[0060]

[0061] When B is a group represented by formula (ii), from the viewpoint of the solubility of the polyimide, the bis(trimellitic anhydride) ester of general formula (2) is preferably 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diylbis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (TAHMBP) represented by the following formula (2-2):

[0062]

[0063] Specific examples of bis(trimellitic anhydride) esters other than those of the above formulas (2-1) and (2-2) include bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-biphenyl-4,4'-diyl, 5,5'-(3,3'-dimethyl[1,1'-biphenyl]-4,4'-diyl)bis(1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylate) (OCBP-TME), p-biphenylene bis(trimellitate anhydride) (BP-TME), tert-butylhydroquinone bis(trimellitate anhydride) (TA.BHQ), trimethylhydroquinone bis(trimellitate anhydride) (TA.TMHQ), and the like.

[0064] A polyimide containing the above-mentioned specific diamine as the diamine component and the specific acid dianhydride as the acid dianhydride component exhibits solubility in organic solvents and has an excellent balance between high transparency and mechanical strength.

[0065] Among the specific acid dianhydrides, from the viewpoints of solubility in organic solvents and transparency, 4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (BPADA), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride (BPF-PA), 5,5'-(9H-fluoren-9-ylidenebis(2-methyl-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylate] (TBIS-MPN), spiro[11H-difuro[3,4-b:3',4'-i] Xanthene-11,9'-[9H]fluorene]-1,3,7,9-tetraone, 5,5'-spiro[9H-fluorene-9,9'-[9H]xanthene]-3',6'-diylbis(1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylate) (TBIS-RXN), 1,4-phenylenebis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (TMHQ), and 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diylbis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (TAHMBP) are preferred.

[0066] Among the specific acid dianhydrides, acid dianhydrides having an ether bond and acid dianhydrides having a cardo structure are preferred from the viewpoint of UV resistance of the polyimide. BPADA, BPAF, and BPF-PA are particularly preferred from the viewpoint of solubility in solvents and mechanical strength. These acid dianhydrides do not have an ester bond and do not undergo Fries transition due to UV light, so that the polyimide is less likely to discolor when exposed to UV light.

[0067] From the viewpoint of making the polyimide soluble in an organic solvent, the total amount of the specific acid dianhydride relative to the total amount of the acid dianhydride components is preferably 15 mol% or more, more preferably 20 mol% or more, even more preferably 25 mol% or more, and may be 30 mol% or more, 35 mol% or more, 40 mol% or more, 45 mol% or more, or 50 mol% or more. The total amount of the specific acid dianhydride relative to the total amount of the acid dianhydride components may be 100 mol%, or may be 95 mol% or less, 90 mol% or less, 85 mol% or less, 80 mol% or less, 75 mol% or less, or 70 mol% or less.

[0068] (Acid dianhydride other than the specific acid dianhydride) The polyimide may contain an acid dianhydride other than the specific acid dianhydride as the acid dianhydride component. Examples of such acid dianhydrides include alicyclic tetracarboxylic acid dianhydrides and aromatic tetracarboxylic acid dianhydrides. From the viewpoint of environmental safety of the polyimide, -C-CF ３ and -C-CF ２ Those which do not contain —C— are preferred, and those which do not contain a fluorine atom are particularly preferred.

[0069] The alicyclic tetracarboxylic dianhydride may have at least one alicyclic structure, and may have both an alicyclic ring and an aromatic ring in one molecule. The alicyclic ring may be polycyclic or may have a spiro structure.Examples of alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,1'-bicyclohexane-3,3',4,4'tetracarboxylic acid-3,4:3',4'-dianhydride, and norbornane-2-spiro-α-cyclopentanoic acid. 2,2'-binorbornane-5,5',6,6'-tetracarboxylic dianhydride, 3-(carboxymethyl)-1,2,4-cyclopentanetricarboxylic acid-1,4:2,3-dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid anhydride, 5-(2,5-dioxotetrahydrofuryl)-3- Methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 5,5'-[cyclohexylidenebis(4,1-phenyleneoxy)]bis-1,3-isobenzofurandione, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride, 3,5,6-tricarboxynorbornane-2-acetic acid 2,3:5,6-dianhydride, decahydro-1,4,5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic dianhydride, tricyclo[6.4.0.0( 2,7)]dodecane-1,8:2,7-tetracarboxylic acid dianhydride, octahydro-1H,3H,8H,10H-biphenyleno[4a,4b-c:8a,8b-c']difuran-1,3,8,10-tetraone, ethylene glycol bis(hydrogenated trimellitic anhydride) ester, decahydro[2]benzopyrano[6,5,4,-def][2]benzopyran-1,3,6,8-tetraone, etc. Inclusion of an alicyclic tetracarboxylic acid dianhydride in addition to the specific acid dianhydride as the acid dianhydride component tends to improve the mechanical strength of the polyimide.

[0070] Among alicyclic tetracarboxylic dianhydrides, from the viewpoint of transparency and mechanical strength of polyimide, 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 1,2,3,4-cyclopentanetetracarboxylic dianhydride (CPDA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (H-PMDA), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride (TDA-100), bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BEDA), bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride (BODA), and 1,1'-bicyclohexane-3,3',4,4'tetracarboxylic acid-3,4:3',4'-dianhydride (H-BPDA) are preferred. Among these, from the viewpoint of mechanical strength, tetracarboxylic dianhydrides in which two acid anhydride groups are bonded to one alicyclic ring are preferred, and CBDA is particularly preferred.

[0071] When an alicyclic tetracarboxylic dianhydride is used in addition to the specific acid dianhydride, the amount of the alicyclic tetracarboxylic dianhydride relative to the total amount of the acid dianhydride components may be 1 mol% or more, 3 mol% or more, 5 mol% or more, 10 mol% or more, 12 mol% or more, or 15 mol% or more. The greater the amount of the alicyclic tetracarboxylic dianhydride, the higher the mechanical strength and heat resistance tend to be. From the viewpoint of ensuring the solubility of the polyimide in organic solvents, the amount of the alicyclic tetracarboxylic dianhydride relative to the total amount of the acid dianhydride components is preferably 80 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less, and may be 40 mol% or less, 30 mol% or less, or 20 mol% or less.

[0072] Examples of aromatic tetracarboxylic dianhydrides other than the specific acid dianhydrides include pyromellitic dianhydride (PMDA), 1,2,3,4-benzenetetracarboxylic dianhydride (MPDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), 2,2',3,3',-biphenyltetracarboxylic dianhydride, Examples of aromatic tetracarboxylic dianhydride include phenyl tetracarboxylic dianhydride (i-BPDA), 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride (DSDA), 5,5'-dimethylmethylenebis(phthalic anhydride), 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, terphenyl tetracarboxylic dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, and bis(3,4-dicarboxyphenyl)sulfone dianhydride. Among these aromatic tetracarboxylic dianhydrides, a-BPDA, s-BPDA, i-BPDA, PMDA, MPDA, and DSDA are preferred from the viewpoint of improving mechanical strength.

[0073] When an aromatic tetracarboxylic dianhydride other than the specific acid dianhydride is used in addition to the specific acid dianhydride, from the viewpoint of ensuring the solubility of the polyimide in an organic solvent, the amount of the aromatic tetracarboxylic dianhydride other than the specific acid dianhydride relative to the total amount of the acid dianhydride components is preferably 80 mol% or less, more preferably 60 mol% or less, even more preferably 50 mol% or less, and may be 40 mol% or less, 30 mol% or less, or 20 mol% or less.

[0074] The polyimide may contain, as an acid dianhydride component, a chain aliphatic tetracarboxylic dianhydride such as ethylene tetracarboxylic dianhydride, 1,2,3,4-butane tetracarboxylic dianhydride, or meso-butane-1,2,3,4-tetracarboxylic dianhydride.

[0075] The amount of the fluorine atom-containing acid dianhydride relative to the total amount of the acid dianhydride components of the polyimide is preferably 30 mol % or less, more preferably 20 mol % or less, and even more preferably 10 mol % or less, and may be 5 mol % or less, 1 mol % or less, or 0.5 mol % or less. The polyimide may not contain a fluorine atom-containing acid dianhydride as an acid dianhydride component.

[0076] Among fluorine atom-containing acid dianhydrides, the structure in which a trifluoromethyl group is bonded to a carbon atom (-C-CF ３ ) and / or a structure in which carbon atoms are bonded to both ends of a difluoromethylene group (—C—CF ２ -C-) has low decomposition properties and is a concern for environmental safety. ３ - or -C(CF ３ ) ２ Acid dianhydrides having a structure in which - is directly bonded (for example, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 9,9-bis(trifluoromethyl)xanthenetetracarboxylic dianhydride, and 9-trifluoromethylxanthenetetracarboxylic dianhydride) are poorly degradable in the environment, and therefore, from the viewpoint of environmental safety of the polyimide, it is preferable that these acid dianhydrides are substantially not contained.

[0077] The amount of CF on the carbon atom of the aromatic ring relative to the total amount of the acid dianhydride component of the polyimide ３ - or -C(CF ３ ) ２ The amount of acid dianhydride to which - is directly bonded is preferably less than 0.5 mol %, and may be 0.3 mol % or less, 0.1 mol % or less, or 0.05 mol % or less, or may be 0. ２ (CF ２ ) ｌ CF ２ The amount of acid dianhydride having - (l is an integer of 1 or more) is preferably less than 0.5 mol %, and may be 0.3 mol % or less, 0.1 mol % or less, or 0.05 mol % or less, or may be 0.

[0078] <Polybasic Acid> As described above, the polyimide may be a polyamideimide containing a structure represented by general formula (II) or (III). By using a dicarboxylic acid and / or a tricarboxylic acid anhydride as the polybasic acid component in addition to a diamine and a tetracarboxylic acid dianhydride, a polyamideimide containing a dicarboxylic acid-derived structure represented by general formula (VIa) and / or a tricarboxylic acid anhydride-derived structure represented by general formula (VIIa) can be obtained.

[0079] Examples of dicarboxylic acids include aliphatic dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-oxybisbenzoic acid, 4,4'-biphenyldicarboxylic acid, and 2-fluoroterephthalic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-hexahydroterephthalic acid, hexahydroisophthalic acid, 1,3-cyclopentanedicarboxylic acid, and bi(cyclohexyl)-4,4'-dicarboxylic acid; and heterocyclic dicarboxylic acids such as 2,5-thiophenedicarboxylic acid and 2,5-furandicarboxylic acid.

[0080] Examples of tricarboxylic acid anhydrides include trimellitic anhydride, 2-fluorotrimellitic anhydride, 5-fluorotrimellitic anhydride, 6-fluorotrimellitic anhydride, 2,5-difluorotrimellitic anhydride, 2,6-difluorotrimellitic anhydride, 5,6-difluorotrimellitic anhydride, and 2,5,6-trifluorotrimellitic anhydride derivatives.

[0081] From the viewpoint of the solubility of the polyamideimide, the polybasic acid is preferably an aromatic dicarboxylic acid, an alicyclic dicarboxylic acid, or trimellitic anhydride, with an aromatic dicarboxylic acid being particularly preferred. Among the aromatic dicarboxylic acids, terephthalic acid, isophthalic acid, 4,4'-biphenyldicarboxylic acid, and 4,4'-oxybisbenzoic acid are preferred, with terephthalic acid and isophthalic acid being particularly preferred, and terephthalic acid being particularly preferred. Among the alicyclic dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid and bi(cyclohexyl)-4,4'-dicarboxylic acid are preferred, with 1,4-cyclohexanedicarboxylic acid being particularly preferred.

[0082] The total amount of terephthalic acid, isophthalic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-oxybisbenzoic acid, 1,4-cyclohexanedicarboxylic acid bi(cyclohexyl)-4,4'-dicarboxylic acid, and trimellitic anhydride relative to the total amount of polybasic acid components of the polyamideimide is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, and may be 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more. The total amount of terephthalic acid and isophthalic acid relative to the total amount of polybasic acid components of the polyamideimide may be 50 mol% or more, 60 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more, and the amount of terephthalic acid may be within this range.

[0083] From the viewpoint of environmental safety of polyamideimide, polyamideimide is a polybasic acid component containing CF ３ - or -C(CF ３ ) ２ It is preferable that the polyamideimide does not substantially contain a polybasic acid having a structure in which - is directly bonded to a carbon atom of an aromatic ring. ３ - or -C(CF ３ ) ２ The amount of polybasic acids directly bonded with - is preferably less than 0.5 mol %, and may be 0.3 mol % or less, 0.1 mol % or less, or 0.05 mol % or less, or may be 0.

[0084] In the preparation of polyamideimide and polyamic acid as its precursor, polybasic acid derivatives such as dicarboxylic acid dichlorides, dicarboxylic acid esters, dicarboxylic acid anhydrides, and tricarboxylic acid anhydride chlorides may be used in place of the polybasic acid.

[0085] In the polyamideimide, the total of the tetracarboxylic dianhydride-derived structure represented by general formula (IVa), the dicarboxylic acid-derived structure represented by general formula (VIa), and the tricarboxylic anhydride-derived structure represented by general formula (VIIa) is preferably 90 to 110 molar parts per 100 molar parts of the diamine-derived structure represented by general formula (Va). The total of the structures of general formulas (IVa), (VIa), and (VIIa) may be 93 to 107 molar parts, 95 to 105 molar parts, 97 to 103 molar parts, or 99 to 101 molar parts per 100 molar parts of the structure of general formula (Va).

[0086] In the polyamideimide, the ratio of the total of the structures of general formula (VIa) and general formula (VIIa) to the total of the structures of general formula (IVa), general formula (VIa), and general formula (VIIa) can be any range from 0 to 100 mol %. The ratio of the structures of general formula (IVa) to the structures of general formula (VIa) is approximately equal to the ratio of the imide structures of general formula (I) to the amide structures of general formula (II), and the ratio of the structures of general formula (IVa) to the structures of general formula (VIIa) is approximately equal to the ratio of the imide structures of general formula (I) to the amide-imide structures of general formula (III). The ratio of the total of the structure of general formula (VIa) and the structure of general formula (VIIa) to the total of the structure of general formula (IVa), the structure of general formula (VIa), and the structure of general formula (VIIa) may be 1 mol% or more, 5 mol% or more, 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, or 50 mol% or more, and may be 80 mol% or less, 75 mol% or less, 70 mol% or less, 65 mol% or less, or 60 mol% or less.

[0087] The higher the ratio of the structures of general formulae (VIa) and (VIIa), that is, the higher the ratio of the amide structure, the more improved the solubility of the polyamideimide in organic solvents may be.

[0088] The amount of polybasic acid relative to the diamine component of the polyamideimide, i.e., the total ratio of the structural units of general formulae (VI) and (VII) to the structural unit of general formula (V), may be 1 mol% or more, 5 mol% or more, 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, or 50 mol% or more, and may be 80 mol% or less, 75 mol% or less, 70 mol% or less, 65 mol% or less, or 60 mol% or less.

[0089] <Content of specific fluorine structure in polyimide> As described above, a polyimide containing a diamine (specific diamine) represented by general formula (X1) as a diamine component and one or more acid dianhydrides (specific acid dianhydrides) selected from the group consisting of acid dianhydrides having an ether bond, acid dianhydrides having a cardo structure, and bis(trimellitic anhydride) esters as an acid dianhydride component is -C-CF ３ , -C-CF ２ It is substantially free of structures such as —C— and exhibits solubility in organic solvents.

[0090] In order to reduce the environmental persistence of fluorine-containing compounds, it is preferable that the polyimide contains a small amount of monomers having a specific fluorine structure. The specific fluorine structure is a trifluoromethyl group (CF ３ -), excluding those containing only the components of the following structural formula (i), and a difluoromethylene group (-CF ２ -), excluding those having only the components of the following structural formula (ii): CF ３ -X (i) X-CF ２ -X' (ii)

[0091] X in formula (i) and (ii) is —OR or —NRR′, and X′ in formula (ii) is —H, —CH ３ , aromatic, —C(O)—, —OR″, —SR″, and NR″R′″. R, R′, R″, and R′″ each independently represent —H, —CH ３ , -CH ２ -, aromatic, or -C(O)-.

[0092] From the viewpoint of improving environmental degradability, the amount of fluorine atoms contained in the specific fluorine structure per 1 kg of polyimide is preferably less than 500 mg, more preferably less than 300 mg, even more preferably less than 100 mg, and particularly preferably less than 50 mg.

[0093] [Preparation of Polyimide] Polyamic acid, which serves as a polyimide precursor, is obtained by the reaction of an acid dianhydride with a diamine, and polyimide is obtained by cyclodehydration (imidization) of the polyamic acid. The method for preparing polyamic acid is not particularly limited, and any known method can be used. For example, a polyamic acid solution can be obtained by dissolving diamine and tetracarboxylic dianhydride in approximately equimolar amounts (molar ratio of 90:100 to 110:100) in an organic solvent and stirring the mixture.

[0094] When preparing polyamideimide, in addition to diamine and tetracarboxylic dianhydride, polybasic acid or its derivative (acid chloride, acid anhydride, etc.) may be used as a monomer to prepare the polyamideimide. In this case, the amount of each monomer may be adjusted so that the total amount of tetracarboxylic dianhydride and polybasic acid or its derivative is approximately equimolar to the diamine.

[0095] The concentration of the polyamic acid solution is usually 5 to 35% by weight, preferably 10 to 30% by weight. When the concentration is within this range, the polyamic acid obtained by polymerization has an appropriate molecular weight, and the polyamic acid solution has an appropriate viscosity.

[0096] In the polymerization of polyamic acid, it is preferable to add the acid dianhydride to the diamine in order to suppress ring-opening of the acid dianhydride. When adding multiple types of diamines or multiple types of acid dianhydrides, they may be added all at once or in multiple portions. The physical properties of the polyimide can also be controlled by adjusting the order of addition of the monomers.

[0097] The organic solvent used in the polymerization of polyamic acid is not particularly limited, as long as it does not react with the diamine and the acid dianhydride and can dissolve the polyamic acid. Examples of organic solvents include urea solvents such as methylurea and N,N-dimethylethylurea; sulfoxide or sulfone solvents such as dimethyl sulfoxide, diphenyl sulfone, and tetramethyl sulfone; amide solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N,N'-diethylacetamide, N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, and hexamethylphosphoric triamide; alkyl halide solvents such as chloroform and dichloromethane; aromatic hydrocarbon solvents such as benzene and toluene; and ether solvents such as tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, dimethyl ether, diethyl ether, and p-cresol methyl ether. These solvents are typically used alone or in combination as needed. From the viewpoint of the solubility and polymerization reactivity of polyamic acid, DMAc, DMF, NMP, etc. are preferably used.

[0098] Polyimides are obtained by dehydration cyclization of polyamic acid. One method for preparing polyimides from a polyamic acid solution is to add a dehydrating agent, an imidization catalyst, etc. to the polyamic acid solution and allow imidization to proceed in the solution. The polyamic acid solution may be heated to accelerate the imidization process. Mixing a solution containing polyimide produced by imidization of polyamic acid with a poor solvent results in the polyimide being precipitated as a solid. Isolating the polyimide as a solid allows impurities generated during the synthesis of the polyamic acid, as well as residual dehydrating agents and imidization catalysts, to be washed and removed with the poor solvent, preventing discoloration of the polyimide and increased yellowness. Furthermore, isolating the polyimide as a solid allows the use of solvents suitable for film formation, such as low-boiling point solvents, when preparing a solution for producing a molded product such as a film.

[0099] The molecular weight of the polyimide (weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC)) is preferably 10,000 to 1,000,000, more preferably 20,000 to 500,000, and even more preferably 40,000 to 400,000. If the molecular weight is too small, the strength of the film may be insufficient. If the molecular weight is too large, the solubility in organic solvents and the moldability and processability during the production of molded articles such as films may be poor.

[0100] The polyimide is preferably soluble in an organic solvent. Specifically, the polyimide is preferably soluble in dimethylformamide (DMF) at 23°C at a concentration of 1% by weight or more. In addition to being soluble in amide solvents such as DMF, the polyimide is preferably soluble in non-amide solvents. Examples of non-amide solvents include ketone solvents such as acetone and methyl ethyl ketone, alkyl halide solvents such as chloroform and dichloromethane, and ester solvents such as ethyl acetate and γ-butyrolactone. Non-amide solvents have a lower boiling point than amide solvents, making it easier to remove residual solvent during film production. Therefore, polyimides that are soluble in non-amide solvents are expected to improve film productivity.

[0101] From the viewpoint of thermal stability and light stability, the polyimide preferably has low reactivity. The acid value of the polyimide is preferably 0.4 mmol / g or less, more preferably 0.3 mmol / g or less, and even more preferably 0.2 mmol / g or less. The acid value of the polyimide may be 0.1 mmol / g or less, 0.05 mmol / g or less, or 0.03 mmol / g or less.

[0102] From the viewpoint of reducing the acid value, it is preferable that the polyimide has a high imidization rate. A low acid value tends to increase the stability of the polyimide. The imidization rate of the polyimide is preferably 90% or more, more preferably 95% or more, and may be 98% or more or 99% or more. The imidization rate of the polyimide is the ratio of the imide structure to the total of the imide structural unit and the amic acid structural unit, １ It can be calculated from the H-NMR spectrum.

[0103] [Molded Articles and Films] The polyimides can be used to form various molded articles, including melt processes such as injection molding, transfer molding, press molding, blow molding, inflation molding, calendar molding, and melt extrusion molding.

[0104] In one embodiment, the molded article is a film. The film may be molded by either a melting method or a solution method, but the solution method is preferred from the viewpoint of producing a film with excellent transparency and uniformity. In the solution method, a solution containing the polyimide is applied to a support, and the solvent is dried and removed to obtain a film.

[0105] The solvent for the solution is not particularly limited as long as it can dissolve the polyimide resin. Examples of the solvent include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; ether solvents such as tetrahydrofuran and 1,4-dioxane; ketone solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, diethyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone; and alkyl halide solvents such as chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, dichlorobenzene, and dichloromethane.

[0106] From the viewpoint of the solubility of polyimide, amide-based solvents are preferred, while from the viewpoint of the removability of the solvent when producing a molded product such as a film, low-boiling non-amide-based solvents are preferred, and ketone-based solvents and alkyl halide-based solvents are preferred because they have excellent solubility for polyimide and low boiling points, making it easy to remove the remaining solvent when producing a film.

[0107] The solids concentration of the polyimide solution may be appropriately set depending on the molecular weight of the polyimide, the thickness of the film, the film-forming environment, etc. The solids concentration is preferably 5 to 30% by weight, more preferably 8 to 20% by weight.

[0108] The polyimide solution may contain organic or inorganic low molecular weight compounds, polymeric compounds (e.g., epoxy resins), etc. The polyimide solution may contain flame retardants, ultraviolet absorbers, crosslinking agents, dyes, pigments, surfactants, leveling agents, plasticizers, fine particles, sensitizers, etc. The fine particles include organic fine particles such as polystyrene and polytetrafluoroethylene, and inorganic fine particles such as colloidal silica, carbon, and layered silicates, and may have a porous or hollow structure. The fiber reinforcing material includes carbon fiber, glass fiber, aramid fiber, etc.

[0109] The resin solution can be applied to a support by a known method using a bar coater, a comma coater, or the like. The support may be a glass substrate, a metal substrate such as SUS, a metal drum, a metal belt, a plastic film, or the like. From the viewpoint of improving productivity, it is preferable to use an endless support such as a metal drum or a metal belt, or a long plastic film as the support and produce the film by a roll-to-roll method. When using a plastic film as the support, it is sufficient to appropriately select a material that is insoluble in the solvent of the film-forming dope.

[0110] It is preferable to heat the film when drying the solvent. The heating temperature is not particularly limited as long as it can remove the solvent and can suppress coloration of the resulting film, and is appropriately set between room temperature and about 250°C, with 50°C to 220°C being preferred. The heating temperature may be increased in stages. In order to increase the efficiency of solvent removal, the resin film may be peeled off from the support and dried after drying has progressed to a certain extent. Heating may be performed under reduced pressure to promote solvent removal.

[0111] The film may be stretched in one or more directions for the purpose of improving the mechanical strength, etc. When the film is stretched, the polymer chains are oriented in the stretching direction, which tends to improve the strength of the film in the in-plane direction and suppress the occurrence of breakage or cracks in the film.

[0112] Films used as cover films or substrate materials for foldable displays are repeatedly folded along the folding axis at the same location, and therefore are required to have high mechanical strength in a direction perpendicular to the folding axis. Therefore, by arranging the film so that the stretching direction is perpendicular to the folding axis, even when the film is repeatedly folded, breakage or cracking of the film at the folding location is unlikely to occur, and a device with high bending resistance can be provided.

[0113] The conditions for stretching the film are not particularly limited. For example, the stretching temperature is about ±40°C of the glass transition temperature of the film, and may be about 120 to 350°C, 150 to 300°C, or 180 to 250°C. The stretching ratio is about 1 to 200%, and may be 5 to 150%, 10 to 120%, or 20 to 100%. The tensile modulus in the stretching direction tends to increase as the stretching ratio increases. On the other hand, if the stretching ratio is excessively large, the mechanical strength in the direction perpendicular to the stretching direction tends to decrease, and the handleability of the film may decrease.

[0114] The film may be biaxially stretched to increase the strength in any in-plane direction. The biaxial stretching may be simultaneous biaxial stretching or sequential biaxial stretching. In biaxial stretching, the stretching ratio in one direction and the stretching ratio in the perpendicular direction may be the same or different. When a difference in stretching ratio is made, the mechanical strength in the direction with the larger stretching ratio tends to be relatively larger. When a biaxially stretched film with anisotropic stretching ratio is used in a foldable device, it is preferable to arrange it so that the direction with the larger stretching ratio is perpendicular to the folding axis.

[0115] The thickness of the film is not particularly limited and may be appropriately set depending on the application. The film thickness is, for example, 5 to 300 μm. From the viewpoint of obtaining a film that is both self-supporting and flexible and has high transparency, the film thickness is preferably 20 μm to 200 μm, and may be 30 μm to 150 μm, 40 μm to 100 μm, or 50 μm to 80 μm. The thickness of a film used as a cover film for a display is preferably 10 μm or more. When the film is stretched, the thickness after stretching is preferably within the above range.

[0116] The haze of the film is not particularly limited, but is preferably 10% or less, more preferably 5% or less, even more preferably 4% or less, and may be 3.5% or less, 3% or less, 2% or less, or 1% or less. The lower the haze of the film, the better.

[0117] The total light transmittance of the film is not particularly limited, but is preferably 87% or more, more preferably 88% or more, and may be 89% or more or 90% or more.

[0118] The yellowness index (YI) of the film is not particularly limited, but is preferably 10 or less, and may be 7.0 or less, 5.0 or less, 3.0 or less, 2.0 or less, or 1.0 or less.

[0119] From the viewpoint of strength, the tensile modulus of the film is preferably 2.0 GPa or more, more preferably 2.5 GPa or more, even more preferably 3.0 GPa or more, and may be 4.0 GPa or more. The pencil hardness of the film is not particularly limited, but is preferably 4B or more, more preferably 2B or more, and even more preferably F or more, and may be H or more, 2H or more, or 3H or more.

[0120] From the viewpoint of heat resistance, the glass transition temperature of the film is preferably 180°C or higher, more preferably 210°C or higher, even more preferably 240°C or higher, and may be 270°C or higher, or even 300°C or higher.

[0121] Films containing the polyimide of the present invention are suitable for use as display materials due to their low coloration and high transparency. In particular, films with high mechanical strength can be applied to surface components such as display cover windows. Furthermore, since the polyimide is substantially free of specific fluorine structures, they are highly degradable and environmentally safe. When used in practice, the film of the present invention may be provided with an antistatic layer, an easy-adhesion layer, a hard coat layer, an antireflection layer, or the like on its surface.

[0122] The following examples will be used to further explain the present invention, but the present invention is not limited to these examples.

[0123] [Preparation of Polyimide Resin] Dimethylformamide (DMF) was placed in a separable flask and stirred under a nitrogen atmosphere. Diamine and tetracarboxylic dianhydride were added in the ratios shown in Table 1, and acetic acid was then added. The mixture was stirred under a nitrogen atmosphere for 1 to 48 hours to react, yielding a polyamic acid solution with a solids concentration of 18% by weight.

[0124] To 100 g of the polyamic acid solution, 5.5 g of pyridine was added as an imidization catalyst. After complete dispersion, 8 g of acetic anhydride was added and the mixture was stirred at 90°C for 3 hours. After cooling to room temperature, 100 g of 2-propyl alcohol (IPA) was added at a rate of 2-3 drops / second while stirring the solution, causing the polyimide resin to precipitate. 150 g of IPA was then added, and the mixture was stirred for approximately 30 minutes, after which it was subjected to suction filtration using a Kiriyama funnel. The resulting solid was washed with IPA and then dried for 12 hours in a vacuum oven set at 120°C to obtain a polyimide resin.

[0125] [Preparation of Polyamide-imide Resin] A polyamide-imide resin was obtained in the same manner as in the preparation of the polyimide resin, except that the diamine, tetracarboxylic dianhydride, and polybasic acid derivative were added in the proportions shown in Table 2, the solids concentration of the polyamic acid solution was changed to 13 wt %, and the amount of pyridine added was changed to 6.5 g.

[0126] [Film Preparation Examples] The above polyimide resin and polyamideimide resin were dissolved in DMF to prepare a solution with a resin content of 10% by weight. The solution was applied to an alkali-free glass plate and heated and dried in air at 60°C, 90°C, 120°C, 150°C, 180°C, and 200°C in that order for 15 minutes at each temperature to prepare a film with a thickness of approximately 50 μm. Note that in Comparative Examples 1 to 4 in Table 1 and Comparative Examples 11 to 14 in Table 2, the polyimide and polyamideimide were insoluble in DMF, and films could not be prepared, so further evaluations were not performed.

[0127] [Evaluation] <Imidization rate of polyimide> A polyimide resin was dissolved in deuterated dimethyl sulfoxide. １H-NMR was measured, and the imidization rate was calculated from the proton integral value of the amide group. The polyimides of Examples 1 to 8 all had an imidization rate of 99% or more.

[0128] <Molecular Weight> The weight-average molecular weight (Mw) of the polyimide resins of Examples 1 to 8 and the polyamideimide resins of Examples 11 to 14 was measured using a gel permeation chromatograph (HLC-8420GPC) manufactured by Tosoh Corporation under the following conditions: Eluent: LiBr (30 mM) + H3PO4 (30 mM) DMF solution Sample concentration: 0.1 wt % Injection pressure: Approximately 1.3 to 1.7 MPa Injection volume: 10 μL Flow rate: 0.6 mL / min Guard column: TSK guard column Super AW-H Column: TSK gel AWM-H × 2 Column temperature: 40°C Detection conditions: RI, UV Molecular weight standard: Polystyrene (manufactured by Tosoh Corporation) Calibration curve order: 1st dimension

[0129] <Glass Transition Temperature> A strip-shaped test piece measuring 25 mm in length and 5 mm in width was cut out from the film, and dynamic viscoelasticity measurement was performed using a dynamic viscoelasticity measuring device (Rheogel-E4000, manufactured by UBM) in tension mode, with an initial chuck distance of 15 mm, a frequency of 10 Hz, and a heating rate of 10°C / min, while the temperature was raised from 30°C to 300°C, to measure the loss tangent tanδ. When tanδ was plotted against temperature, the temperature at which tanδ showed a maximum value was taken as the glass transition temperature (Tg).

[0130] <Haze and Total Light Transmittance> The film was cut into a 3 cm square, and the haze and total light transmittance (TT) were measured using a haze meter "HZ-V3" manufactured by Suga Test Instruments in accordance with JIS K7136 and JIS K7361-1.

[0131] <Yellowness Index> The film was cut into a 3 cm square, and the yellowness index (YI) was measured according to JIS K7373 using a spectrophotometer "SC-P" manufactured by Suga Test Instruments.

[0132] <Tensile Modulus> The polyimide films of Examples 1 to 8 were cut into strips with a width of 10 mm, and after standing at 23°C / 55% RH for 1 day to condition the humidity, the tensile modulus was measured using an "AUTOGRAPH AGS-X" manufactured by Shimadzu Corporation under the following conditions: Grip distance: 100 mm, Pulling speed: 20.0 mm / min, Measurement temperature: 23°C.

[0133] [Evaluation Results] The compositions of the polyimides in the Examples and Comparative Examples, and the evaluation results of the polyimide resins and polyimide films in the Examples, are shown in Table 1. The compositions of the polyamideimides in the Examples and Comparative Examples, and the evaluation results of the polyamideimide resins and polyamideimide films in the Examples, are shown in Table 2. In Tables 1 and 2, compounds are represented by the following abbreviations. The compositions in Tables 1 and 2 are shown as molar ratios, with the total amount of diamine being 100 parts by mole.

[0134] <Diamines> TFPA: 1,4-bis(4-aminophenoxy)tetrafluorobenzene OFPA: 2,2',3,3',5,5',6,6'-octafluoro-4,4'-bis(4-aminophenoxy)-1,1'biphenyl DDS: 3,3'-diaminodiphenyl sulfone BAFL: 9,9-bis(4-aminophenyl)fluorene ODA: 4,4'-diaminodiphenyl ether <Acid dianhydrides> BPADA: 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride TAHMBP: 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diylbis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride PMDA: pyromellitic dianhydride <Polybasic acid chloride> TPC: terephthalic acid dichloride

[0135]

[0136]

[0137] In Table 1, the polyimides of Examples 1 to 8, which contained a specific diamine as the diamine component and a specific acid dianhydride as the acid dianhydride component, were soluble in organic solvents and could be used to prepare transparent films. On the other hand, in Comparative Examples 1 to 4, which contained a specific diamine but no specific acid dianhydride, the polyimides were insoluble in organic solvents. The same was true in Table 2.

[0138] These results demonstrate that by using a specific diamine as the diamine component and appropriately selecting an acid dianhydride, it is possible to obtain polyimides and polyamideimides that are highly environmentally safe and have excellent solubility in organic solvents and transparency.

Claims

1. A polyimide having a diamine component and a tetracarboxylic dianhydride component, comprising, as the diamine component, a diamine represented by general formula (X1), and as the tetracarboxylic dianhydride component, one or more tetracarboxylic dianhydrides selected from the group consisting of tetracarboxylic dianhydrides having an ether bond, tetracarboxylic dianhydrides having a cardo structure, and bis(trimellitic anhydride) esters: In the general formula (X1), n ​​is an integer of 1 to 5, R １ ~R ８ are each independently a hydrogen, an alkyl chain, a halogen, or an alkoxy group.

2. The polyimide according to claim 1, wherein the diamine represented by general formula (X1) is one or more selected from the group consisting of 1,4-bis(4-aminophenoxy)tetrafluorobenzene, 1,4-bis(4-amino-3-methylphenoxy)tetrafluorobenzene, 1,4-bis(4-amino-3,5-dimethylphenoxy)tetrafluorobenzene, 2,2',3,3',5,5',6,6'-octafluoro-4,4'-bis(4-aminophenoxy)-1,1'biphenyl, 2,2',3,3',5,5',6,6'-octafluoro-4,4'-bis(4-amino-3-methylphenoxy)-1,1'biphenyl, and 2,2',3,3',5,5',6,6'-octafluoro-4,4'-bis(4-amino-3,5-dimethylphenoxy)-1,1'biphenyl.

3. The one or more tetracarboxylic dianhydrides selected from the group consisting of tetracarboxylic dianhydrides having an ether bond, tetracarboxylic dianhydrides having a cardo structure, and bis(trimellitic anhydride) esters are selected from the group consisting of 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride, 5,5'-(9H-fluoren-9-ylidenebis(2-methyl-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylate], spiro[11H-difuro[3,4-b 2. The polyimide of claim 1, comprising one or more tetracarboxylic dianhydrides selected from the group consisting of 5,5'-spiro[9H-fluorene-9,9'-[9H]xanthene]-3',6'-diylbis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate), 1,4-phenylenebis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate), and 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diylbis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate).

4. The amount of CF on the carbon atom of the aromatic ring relative to the total amount of the diamine component ３ - or -C(CF ３ ) ２ The amount of the diamine having a structure in which - is directly bonded is less than 0.5 mol %, and the amount of the diamine having a structure in which - is directly bonded to a carbon atom of an aromatic ring is less than 0.5 mol % based on the total amount of the tetracarboxylic dianhydride component. ３ - or -C(CF ３ ) ２ 2. The polyimide according to claim 1, wherein the amount of the tetracarboxylic dianhydride having a structure in which - is directly bonded is less than 0.5 mol %.

5. -CF relative to the total amount of diamine components ２ (CF ２ ) ｍ CF ２ The amount of diamine having -(m is an integer of 1 or more) is less than 0.5 mol %, and the amount of -CF ２ (CF ２ ) ｌ CF ２ 2. The polyimide according to claim 1, wherein the amount of tetracarboxylic dianhydride having -(l is an integer of 1 or more) is less than 0.5 mol %.

6. The polyimide according to claim 1, having an imidization rate of 90% or more.

7. The polyimide of claim 1, which is soluble in dimethylformamide at 23°C.

8. The polyimide according to any one of claims 1 to 7, further comprising an amide structural unit formed by bonding the diamine component with a polybasic acid component.

9. The amount of CF on the carbon atom of the aromatic ring relative to the total amount of polybasic acid components ３ - or -C(CF ３ ) ２ 9. The polyimide according to claim 8, wherein the amount of the polybasic acid having a structure in which - is directly bonded is less than 0.5 mol %.

10. -CF relative to the total amount of polybasic acid components ２ (CF ２ ) ｊ CF ２ 9. The polyimide according to claim 8, wherein the amount of the polybasic acid having -(j is an integer of 1 or more) is less than 0.5 mol %.

11. A molded article comprising the polyimide according to any one of claims 1 to 7.

12. A molded article comprising the polyimide according to claim 8.

13. A film comprising the polyimide according to any one of claims 1 to 7.

14. A film comprising the polyimide of claim 8.

Images