Resin compositions, films, and flexible displays

Abstract

The objective is to provide a resin composition that can produce a film with good colorless properties using monomers that do not fall under the category of PFAS. [Solution] A resin composition comprising one or more resins selected from aromatic polyimide resins, aromatic polyamideimide resins, and aromatic polyamide resins, and an antioxidant comprising at least one antioxidant selected from lactone-based antioxidants and antioxidants having a t-butyl group at one ortho position of an oxygen atom bonded to a benzene ring and an alkyl group which may be substituted at the other ortho position, wherein the resin has a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring.

Description

[Technical Field]

[0001] The present invention relates to resin compositions, films, and flexible displays. [Background technology]

[0002] Display device components such as liquid crystal displays and organic light-emitting diodes (OLEDs) are widely used in various applications such as mobile phones and tablets. Traditionally, glass, typified by UTG (Ultra-Thin Glass), has been used as the front panel material for such display devices. However, while glass offers high transparency and, depending on the type, can exhibit high hardness, it is also very rigid and brittle. Therefore, this type of glass is difficult to use as the front panel material for flexible displays that are bent or folded.

[0003] Therefore, films utilizing polymer materials are being considered as an alternative to glass. Films containing polymer materials readily exhibit flexible properties, and are expected to be used in various applications such as flexible displays.

[0004] Conventionally, flexible displays have sometimes developed marks on their surface, such as pressure marks or creases, when operated by touch or a stylus, or when held in a folded state for extended periods. Therefore, films for such flexible displays are required to have excellent mechanical strength (such as elastic modulus). In addition, films for such flexible displays are also required to have excellent optical properties, such as transparency.

[0005] For example, Patent Document 1 proposes a polyamide film having a specific structural unit. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2019-001853 [Overview of the project] [Problems that the invention aims to solve]

[0007] In Patent Document 1, 2,2'-bis(trifluoromethyl)benzidine (TFMB), used as a diamine monomer, has a trifluoromethyl group in its molecule and is a compound that falls under the category of so-called PFAS (Per- and polyfluoroalkyl substances). Compounds that fall under the category of PFAS are restricted or may be restricted in use by laws and regulations both domestically and internationally due to concerns about their impact on the environment or human health.

[0008] Therefore, there is a need for a resin composition that can exhibit film properties (mechanical strength, transparency, and colorlessness) while avoiding the use of compounds that fall under the category of PFAS, including TFMB.

[0009] The inventors focused on monomers having a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring, as monomers that do not fall under the category of PFAS, and conducted diligent research. However, they discovered a new problem: resins using these monomers tend to lose their colorlessness.

[0010] Therefore, the object of the present invention is to solve the above problems and provide a resin composition that can produce a film with good colorlessness using monomers that do not fall under the category of PFAS. Furthermore, a further objective of the present invention is to provide a film using such a resin composition, and a flexible display using the film. [Means for solving the problem]

[0011] The present inventors conducted diligent studies to solve the above problems and found that the above problems can be solved by providing a resin composition containing an aromatic polyamide-imide resin, an aromatic polyamide resin, or an aromatic polyimide resin having a specific structure, and a specific antioxidant, thus completing the present invention. The gist of the present invention, which solves the above problems, is as follows.

[0012] [1] One or more resins selected from aromatic polyimide resins, aromatic polyamideimide resins and aromatic polyamide resins, and The antioxidant comprises at least one antioxidant selected from lactone-based antioxidants and antioxidants having a t-butyl group at one ortho position of an oxygen atom bonded to a benzene ring and an alkyl group which may be substituted at the other ortho position. The resin has a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring. Resin composition.

[0013] [2] The resin composition according to [1], wherein the resin has no perfluoroalkyl portion and no polyfluoroalkyl portion.

[0014] [3] The resin composition according to [1] or [2], wherein the antioxidant having a t-butyl group at one ortho position of the oxygen atom bonded to the benzene ring and an optionally substituted alkyl group at the other ortho position is a phenolic antioxidant or a phosphite antioxidant.

[0015] [4] The resin composition according to any one of [1] to [3], wherein the content of the antioxidant is 0.01 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the resin.

[0016] [5] The resin composition according to any one of [1] to [4], wherein a nitrogen atom derived from an amino group is bonded to a benzene ring to which the carbon atom having a hydrogen atom is directly bonded.

[0017] [6] The resin film according to [5], wherein the resin has a residue derived from an aromatic diamine compound represented by the following formula (1). [Chemical formula] In the formula, n is 0 or 1, R1 and R2 are each independently -CH3, -CH2R c , a , b , , -CHR b R c , -CR d R e R f , or a halogen atom, R a ~R e are each independently an alkyl group, an alkenyl group, or an aryl group, X is a single bond, -CH2-, -CHR f -, -CR g R h -, -O-, -S-, -S(=O)2, -C(=O)O-, -C(=O)-NH-, or -C(=O)-, R f ~R h are each independently an alkyl group, an alkenyl group, or an aryl group, or R g and R h may together with the carbon atom to which they are attached form a carbocyclic ring, p represents an integer from 0 to 4, q represents an integer from 0 to 4, When n is 0, p is an integer of 1 or more, and at least one R1 is -CH3, -CH2R​​​​​​​​​​​​​​​​​​​​ (iii) q is an integer greater than or equal to 1, and at least one R2 is -CH3, -CH2R a or -CHR b R c That is the case.

[0018] [7] The resin composition according to any one of [1] to [6] further comprising one or more selected from phosphate ester compounds and phosphonic acid compounds.

[0019] [8] The phosphonic acid compound is a phosphonic acid compound represented by the following formula (5A): The phosphate ester compound is a orthophosphate ester compound represented by the following formula (5B), or a condensed phosphate ester represented by the following formula (5C). The resin composition described in [7]. [ka] During the ceremony, R 21 and R 22 Each of these is independently a hydrogen atom, an alkyl group, or an aryl group, and the alkyl group and aryl group may have substituents. R 23 is an alkyl group or an aryl group, and the alkyl group and aryl group may have substituents. [ka] During the ceremony, R 24 ~R 26 Each of these is independently a hydrogen atom, an alkyl group, or an aryl group, and the alkyl group and aryl group may have substituents, However, R 24 ~R 26 Not all of them are hydrogen atoms. [ka] During the ceremony, R 27 and R 28Each of these is independently an alkyl group or aryl group which may have substituents, Z is a divalent organic group containing at least one aromatic ring, and n is an integer greater than or equal to 1.

[0020] [9] The resin composition according to [7], wherein the content of the phosphate ester compound and the phosphonic acid compound is 1 part by mass or more and 25 parts by mass or less in total per 100 parts by mass of the polyamide resin.

[0021]

[10] The resin composition according to any one of [1] to [9], further comprising a filler.

[0022]

[11] The resin composition according to

[10] , wherein the filler is a fibrous alumina filler.

[0023]

[12] A film comprising any one of the resin compositions described in [1] to

[11] .

[0024]

[13] A flexible display including the film described in

[12] . [Effects of the Invention]

[0025] According to the present invention, it is possible to provide a resin composition that can produce a film with good colorlessness using monomers that do not fall under the category of PFAS. Furthermore, according to the present invention, it is possible to provide a film using such a resin composition, and a flexible display using the film. [Modes for carrying out the invention]

[0026] The resin composition, film, and flexible display of the present invention will be described in detail below based on their embodiments.

[0027] <Resin composition> The resin composition of this embodiment is One or more resins selected from aromatic polyimide resins, aromatic polyamideimide resins, and aromatic polyamide resins, and The antioxidant comprises one or more antioxidants selected from lactone-based antioxidants and antioxidants having a t-butyl group at one ortho position of an oxygen atom bonded to a benzene ring and an alkyl group which may be substituted at the other ortho position. The resin is characterized in that it has a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring.

[0028] (resin) The resin composition of this embodiment comprises one or more resins selected from aromatic polyamide-imide resins, aromatic polyamide resins, and aromatic polyimide resins, wherein the resin has a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring.

[0029] In a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring, the carbon atom containing the hydrogen atom is called the "specified carbon atom." A given carbon atom may have at least one hydrogen atom, but may also have multiple hydrogen atoms. In other words, a given carbon atom may be bonded to at least one hydrogen atom, but may also be bonded to multiple hydrogen atoms.

[0030] The specified carbon atoms may be present in the side chains of the resin or incorporated into the main chain.

[0031] Examples of cases in which a predetermined carbon atom exists in the side chain of a resin include cases in which the resin has an alkyl group in its side chain that may have substituents, and the alkyl group is directly bonded to a benzene ring (provided that the carbon atom of the alkyl group directly bonded to the benzene ring has at least one hydrogen atom). Here, the alkyl group in the alkyl group which may have substituents may be linear or branched, and examples include alkyl groups having 1 to 5 carbon atoms, preferably alkyl groups having 1 to 3 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. Furthermore, examples of substituents on alkyl groups include alkenyl groups (for example, alkenyl groups with 2 to 6 carbon atoms) and aryl groups (for example, aryl groups with 6 to 10 carbon atoms).

[0032] The predetermined carbon atoms (carbon atoms having hydrogen atoms) in the side chain of the resin are preferably carbon atoms having a hydrogen atom at the benzyl position in an alkyl group directly bonded to a benzene ring.

[0033] Examples of cases in which a resin has a structure in which a predetermined number of carbon atoms are incorporated into the main chain of the resin include cases in which the resin has an alkylene group in its main chain that may have substituents, and the alkylene group is directly bonded to a benzene ring (provided that the carbon atoms of the alkyl group directly bonded to the benzene ring have at least one hydrogen atom). Here, the alkylene group may be linear or branched, and examples include alkylene groups having 1 to 5 carbon atoms, preferably alkylene groups having 1 to 3 carbon atoms, such as methylene groups, ethylene groups, n-propylene groups, and isopropylene groups. Examples of substituents include alkenyl groups (e.g., alkenyl groups with 2 to 6 carbon atoms) and aryl groups (e.g., aryl groups with 6 to 10 carbon atoms).

[0034] When the main chain has a structure in which an alkylene group, which may have substituents, is directly bonded to a benzene ring (provided that the carbon atoms of the alkylene group directly bonded to the benzene ring have at least one hydrogen atom), it is preferable that the main chain has a structure in which an alkylene group having an aryl group with 6 to 10 carbon atoms is directly bonded to a benzene ring.

[0035] Aromatic polyamide-imide resins are resins obtained by reacting monomer components such as aromatic diamine compounds, aromatic tetracarboxylic acid compounds, and aromatic dicarboxylic acid compounds, for example. Aromatic polyamide resins are resins obtained by reacting monomer components such as aromatic diamine compounds and aromatic dicarboxylic acid compounds, for example. Aromatic polyimide resins are resins obtained by reacting monomer components such as aromatic diamine compounds and aromatic tetracarboxylic acid compounds, for example. In aromatic polyamide-imide resins, aromatic polyamide resins, and aromatic polyimide resins, the structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring may be present in units derived from aromatic diamine compounds, in units derived from aromatic carboxylic acids (aromatic tetracarboxylic acids or aromatic dicarboxylic acids), or in both units. Preferably, the structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring is present in units derived from aromatic diamine compounds.

[0036] When a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring exists in a unit derived from an aromatic diamine compound, it is preferable that the carbon atom containing the hydrogen atom (a predetermined carbon atom) in the structure in which the carbon atom containing the hydrogen atom is directly bonded to a benzene ring to which a nitrogen atom derived from an amino group is bonded. In other words, a nitrogen atom derived from an amino group is bonded to a benzene ring to which a carbon atom containing a hydrogen atom is directly bonded.

[0037] The resin is more preferably having residues derived from an aromatic diamine compound represented by the following formula (1). [ka] During the ceremony, n is either 0 or 1. R1 and R2 are independently -CH3 and -CH2R, respectively. a ,-CHR b R c ,-CR d R e Rf , or a halogen atom, R a ~R e Each of these is independently an alkyl group, an alkenyl group, or an aryl group. X is a single bond, -CH2-, -CHR f -, -CR g R h -, -O-, -S-, -S(=O)2, -C(=O)O-, -C(=O)-NH-, or -C(=O)- R f ~R h Each of these is independently an alkyl group, an alkenyl group, or an aryl group, or R g and R h These may also form a carbon ring together with the carbon atoms to which they are bonded. p represents an integer from 0 to 4. q represents an integer from 0 to 4. If n is 0, p is an integer greater than or equal to 1, and at least one R1 is -CH3, -CH2R a or -CHR b R c And, If n is 1, then at least one of the following conditions (i) to (iii) is satisfied. (i) X is -CH2- or -CHR f - is (ii) p is an integer greater than or equal to 1, and at least one R1 is -CH3, -CH2R a or -CHR b R c That is (iii) q is an integer greater than or equal to 1, and at least one R2 is -CH3, -CH2R a or -CHR b R c That is the case.

[0038] In formula (1), examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc., and chlorine atoms are preferred.

[0039] In formula (1), the alkyl group may be linear or branched, and examples include alkyl groups having 1 to 6 carbon atoms, preferably alkyl groups having 1 to 4 carbon atoms, such as a methyl group or an ethyl group.

[0040] In formula (1), the alkenyl group may be an alkenyl group having 2 to 6 carbon atoms, preferably an alkenyl group having 2 to 4 carbon atoms, such as a vinyl group.

[0041] In formula (1), the aryl group may be an aryl group having 6 to 15 carbon atoms, preferably an aryl group having 6 to 12 carbon atoms, such as a phenyl group or a naphthyl group.

[0042] R g and R h These may form a carbocyclic ring together with the carbon atoms to which they are bonded. The carbocyclic ring is not particularly limited as long as the ring constituent atoms are carbon atoms, and may be an unsaturated or saturated fatty ring or an aromatic ring. The ring may be monocyclic or polycyclic, and in the case of polycyclic, it may be a fused polycyclic ring. The ring may have 30 or fewer carbon atoms, and examples include indan rings and fluorene rings, with the formation of a fluorene ring being preferable.

[0043] When n is 0, the aromatic diamine compound represented by formula (1) above is preferably represented by the following formula (1-1). [ka] During the ceremony, R3 is -CH3, -CH2R a or -CHR b R c This represents, R a ~R c This is equivalent to equation (1), p1 is an integer between 1 and 4.

[0044] When n is 1, the aromatic diamine compound represented by formula (1) above is preferably represented by the following formula (1-2A) or formula (1-2B). [ka] During the ceremony, R3 and R4 are -CH3 and -CH2R a or -CHR b R c This represents, R a ~R c This is equivalent to equation (1), X, p, and q are equivalent to those in equation (1), but p and q are not both zero at the same time. [ka] In the formula, R1, R2, p, and q are equivalent to those in formula (1) above. Y is either -CH2- or -CHR f -and, R f This is equivalent to equation (1).

[0045] In the above formula (1-2A), p and q are each preferably 1 or 2 independently, and more preferably both p and q are 1.

[0046] In the above formula (1-2A), it is preferable that at least one R3 and R4 are bonded to the amino group at the meta position.

[0047] In the above formula (1-2A), R3 and R4 are preferably -CH3, -C2H5, etc., independently of each other.

[0048] In the above formula (1-2A), X is preferably a single bond, -CH2-, or fluorene ring residue.

[0049] In the above formula (1-2B), Y is preferably -CH2-.

[0050] In the above formula (1-2B), p and q are each preferably 0 or 1 independently, and more preferably both p and q are 0 or both are 1.

[0051] In the above formula (1-2B), R1 and R2 are preferably a methyl group, an ethyl group, or a halogen atom.

[0052] Examples of aromatic diamine compounds represented by formula (1) include 2,2'-dimethylbenzidine, 3,3'-dimethylbenzidine, 3,3',5,5'-tetramethylbenzidine, 9,9-bis(4-amino-3-methylphenyl)fluorene, 4,4'-methylenebis(2,6-diethylaniline), 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-methylenebis(2-ethyl-6-methylaniline), 4,4'-methylenebis(2-ethylaniline), 4,4'-methylenebis(2-chloroaniline), 4,4'-diaminodiphenylmethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 2,5-diaminotoluene, and 2,5-dimethyl-1,4-phenylenediamine. The following aromatic diamine compounds are particularly preferred. The compounds listed below, from top to bottom, are 2,2'-dimethylbenzidine and 9,9-bis(4-amino-3-methylphenyl)fluorene. From the viewpoint of excellent transparency and mechanical strength of the resulting film, 2,2'-dimethylbenzidine is particularly preferred as the aromatic diamine compound represented by formula (1). [ka]

[0053] When a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring exists in a unit derived from an aromatic dicarboxylic acid compound, it is even more preferable that it has a residue derived from an aromatic dicarboxylic acid compound represented by the following formula (2). In the reaction, the aromatic dicarboxylic acid compound may be a derivative such as an acid chloride. [ka] In the equation, R1, R2, X, p, q, and n are equivalent to those in equation (1).

[0054] When a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring exists in a unit derived from an aromatic tetracarboxylic acid compound, it is even more preferable that it has a residue derived from an aromatic tetracarboxylic acid compound represented by the following formula (3). In the reaction, the aromatic tetracarboxylic acid compound may be a derivative of an acid anhydride, acid chloride, etc. [ka] In the formula, R1, R2, p, q, and X are synonymous with formula (1), and the examples and preferred examples described with respect to formula (1) apply.

[0055] Examples of aromatic dicarboxylic acid compounds represented by formula (2) or aromatic tetracarboxylic acid compounds represented by formula (3) include 4,4'-methylenedibenzoic acid, 2-methylterephthalic acid, and 2,5-dimethylterephthalic acid. In the reaction, derivatives of these compounds, such as acid chlorides, may also be used.

[0056] In the resin composition of this embodiment, if the resin has a fluorinated alkyl group, it is preferable that at least one hydrogen atom, chlorine atom, bromine atom, or iodine atom is bonded to the carbon atom of the fluorinated alkyl group. In other words, it is preferable that the resin in the resin film of this embodiment does not have perfluoroalkyl and polyfluoroalkyl portions. Here, perfluoroalkyl and polyfluoroalkyl portions refer to "portions containing a completely fluorinated methyl group or methylene group (a carbon atom to which fluorine is bonded that does not have H, Cl, Br, or I atoms bonded)." This is because if the resin in the resin film of this embodiment has perfluoroalkyl and polyfluoroalkyl portions, the resin may fall under the category of PFAS and be subject to legal regulations. Specifically, the perfluoroalkyl and polyfluoroalkyl moieties include, for example, trifluoromethyl (-CF3) and perfluoroalkylene (-CF2). n -) (provided that the carbon atom to which fluorine is bonded does not have H, Cl, Br, or I atoms bonded to it), and these may further be bonded to alkyl groups or alkylene groups, specifically, for example, -(CH2) n The group represented by CF3, -(CF2) n Examples include groups represented by CH3.

[0057] In the resin composition of this embodiment, the proportion of units having a structure in which a carbon atom with a hydrogen atom is directly bonded to a benzene ring is preferably 10 mol% or more, and more preferably 25 mol% or more, out of the total units. The proportion of units having a structure in which a carbon atom with a hydrogen atom is directly bonded to a benzene ring may be 100 mol%, but in order to obtain the effect of introducing units other than those having a structure in which a carbon atom with a hydrogen atom is directly bonded to a benzene ring, units that do not have a structure in which a carbon atom with a hydrogen atom is directly bonded to a benzene ring (hereinafter also referred to as "other units") may be introduced. In the resin composition of this embodiment, the proportion of units having a structure in which a carbon atom with a hydrogen atom is directly bonded to a benzene ring is preferably 90 mol% or less, more preferably 70 mol% or less, and particularly preferably 55 mol% or less, out of the total units.

[0058] When a unit derived from an aromatic diamine compound has a structure in which a carbon atom with a hydrogen atom is directly bonded to a benzene ring, the proportion of units having this structure among all units derived from the aromatic diamine compound is preferably 20 mol% or more, and more preferably 50 mol% or more. The proportion of units having this structure among all units derived from the aromatic diamine compound may be 100 mol%, but units derived from aromatic diamine compounds that do not have a structure in which a carbon atom with a hydrogen atom is directly bonded to a benzene ring (hereinafter also referred to as "other aromatic diamine compounds") may be introduced. When introducing units derived from other aromatic diamine compounds, the proportion of such units is preferably 10 mol% or more, and more preferably 20 mol% or more, in order to enjoy the effects thereon. If a unit derived from an aromatic diamine compound has a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring, then units derived from aromatic dicarboxylic acid compounds and / or aromatic tetracarboxylic acid compounds may only be units derived from aromatic dicarboxylic acid compounds that do not have a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring (hereinafter also referred to as "other aromatic dicarboxylic acid compounds") and / or aromatic tetracarboxylic acid compounds that do not have a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring (hereinafter also referred to as "other aromatic dicarboxylic acid compounds").

[0059] When a unit derived from an aromatic dicarboxylic acid compound or aromatic tetracarboxylic acid compound has a structure in which a carbon atom with a hydrogen atom is directly bonded to a benzene ring, the proportion of units having this structure among all units derived from the aromatic dicarboxylic acid compound or aromatic tetracarboxylic acid compound is preferably 20 mol% or more, and more preferably 50 mol% or more. The proportion of units having this structure among all units derived from the aromatic dicarboxylic acid compound or aromatic tetracarboxylic acid compound may be 100 mol%, but units derived from other aromatic dicarboxylic acid compounds or other aromatic tetracarboxylic acid compounds may also be introduced. When units derived from other aromatic dicarboxylic acid compounds or other aromatic tetracarboxylic acid compounds are introduced, the proportion of such units is preferably 10 mol% or more, and more preferably 20 mol% or more, in order to enjoy the effects thereon. If a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring exists in a unit derived from an aromatic dicarboxylic acid compound or an aromatic tetracarboxylic acid compound, then the unit derived from the aromatic diamine compound may consist only of units derived from other aromatic diamine compounds.

[0060] Furthermore, when a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring exists in units derived from aromatic dicarboxylic acid compounds and aromatic tetracarboxylic acid compounds, the proportion of units having a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring among all units derived from aromatic dicarboxylic acid compounds and aromatic tetracarboxylic acid compounds is preferably 20 mol% or more, and more preferably 50 mol% or more. The proportion of units having a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring among all units derived from aromatic dicarboxylic acid compounds and aromatic tetracarboxylic acid compounds may be 100 mol%, but units derived from other aromatic dicarboxylic acid compounds and other aromatic tetracarboxylic acid compounds may also be introduced. When units derived from other aromatic dicarboxylic acid compounds and other aromatic tetracarboxylic acid compounds are introduced, the proportion of such units is preferably 10 mol% or more, and more preferably 20 mol% or more, in order to enjoy the effects thereon. If a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring exists in units derived from aromatic dicarboxylic acid compounds and aromatic tetracarboxylic acid compounds, then units derived from aromatic diamine compounds may consist only of units derived from other aromatic diamine compounds.

[0061] In the resin composition of this embodiment, if the resin contains units derived from aromatic diamine compounds and units derived from aromatic dicarboxylic acids, it is preferable that the resin contains units derived from aromatic diamine compounds having a structure in which a carbon atom with a hydrogen atom is directly bonded to a benzene ring, and units derived from other aromatic dicarboxylic acid compounds. More preferably, the units derived from aromatic diamine compounds present in the resin consist of units derived from aromatic diamine compounds having a structure in which a carbon atom with a hydrogen atom is directly bonded to a benzene ring, and the units derived from aromatic dicarboxylic acids present in the resin consist of units derived from other aromatic dicarboxylic acid compounds, i.e., it is an aromatic polyamide resin. Specifically, in the resin composition of this embodiment, if units derived from aromatic diamine compounds and units derived from aromatic dicarboxylic acids are present, it is preferable that the resin has units derived from at least one aromatic diamine compound selected from 2,2'-dimethylbenzidine and 9,9-bis(4-amino-3-methylphenyl)fluorene and units derived from at least one aromatic dicarboxylic acid compound selected from terephthalic acid, terephthalic acid derivatives, 4,4'-oxybisbenzoic acid, and 4,4'-oxybisbenzoic acid derivatives, and it is more preferable that the resin has units derived from at least one aromatic diamine compound selected from 2,2'-dimethylbenzidine and 9,9-bis(4-amino-3-methylphenyl)fluorene and units derived from at least one aromatic dicarboxylic acid compound selected from terephthalic acid chloride (TPC) and 4,4'-oxybis(benzoyl chloride) (DEDC). Among the above, in the resin composition of this embodiment, when units derived from aromatic diamine compounds and units derived from aromatic dicarboxylic acids are present, it is preferable from the viewpoint of excellent transparency and mechanical strength to have units derived from 2,2'-dimethylbenzidine and units derived from 4,4'-oxybis(benzoyl chloride), or to have units derived from 2,2'-dimethylbenzidine and units derived from terephthalic acid chloride (TPC) and 4,4'-oxybis(benzoyl chloride) (DEDC). Furthermore, in the resin composition of this embodiment, when units derived from aromatic diamine compounds and units derived from aromatic dicarboxylic acids are present, it is preferable from the viewpoint of excellent colorlessness to have units derived from 2,2'-dimethylbenzidine and 9,9-bis(4-amino-3-fluorophenyl)fluorene and units derived from 4,4'-oxybis(benzoyl chloride) (DEDC).

[0062] The following describes aromatic polyamide-imide resins, aromatic polyamide resins, and aromatic polyamide resins, respectively.

[0063] [Aromatic polyamide-imide resin] Aromatic polyamide-imide resins are polyamide-imide resins in which nitrogen atoms derived from amino groups are directly bonded to aromatic rings (having aromatic rings in the main chain). Aromatic polyamide-imide resins are resins obtained, for example, by reacting monomer components such as aromatic diamine compounds, aromatic tetracarboxylic acid compounds, and aromatic dicarboxylic acid compounds. Specifically, aromatic polyamide-imide resins are obtained by reacting aromatic diamine compounds with aromatic tetracarboxylic acid compounds to synthesize a polymer having an imide precursor structure, then reacting the polymer with an aromatic dicarboxylic acid compound to synthesize a copolymer having an imide precursor structure and an amide structure, and then performing a ring-closing reaction (imidization) on the imide precursor structure in the copolymer. Alternatively, a polymer having an imide precursor structure may be synthesized by reacting aromatic diamine compounds with aromatic tetracarboxylic acid compounds, and after performing a ring-closing reaction on the imide precursor, it may be reacted with an aromatic dicarboxylic acid compound to synthesize a copolymer (aromatic polyamide-imide resin) having an imide structure and an amide structure.

[0064] Aromatic polyamide-imide resins have a structure in which residues obtained by reacting aromatic diamine compounds and aromatic tetracarboxylic acid compounds are bonded via imide structures to structural units, and residues obtained by reacting aromatic dicarboxylic acid compounds are bonded via amide structures to these units.

[0065] The aromatic polyamide-imide resin in the resin composition of this embodiment has a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring. In this case, it is preferable that the carbon atom having a hydrogen atom (a predetermined carbon atom) in the structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring to which a nitrogen atom derived from an amino group is bonded is directly bonded.

[0066] When a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring exists in a unit derived from an aromatic diamine compound, it is preferable that the carbon atom having a hydrogen atom in the structure in which the carbon atom having a hydrogen atom is directly bonded to a benzene ring to which a nitrogen atom derived from an amino group is bonded.

[0067] Furthermore, if a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring exists in a unit derived from an aromatic diamine compound, it is more preferable that the aromatic polyamide-imide resin in the resin composition of this embodiment has a residue derived from the aromatic diamine compound represented by formula (1) above. For an explanation of formula (1), refer to the explanation in the (Resin) section.

[0068] Furthermore, aromatic diamine compounds include, for example, 2,4-toluenediamine, 2,2'-dimethylbenzidine, 3,3'-dimethylbenzidine, 3,3',5,5'-tetramethylbenzidine, 9,9-bis(4-amino-3-methylphenyl)fluorene, 4,4'-methylenebis(2,6-diethylaniline), 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-methylenebis(2-ethyl-6-methylaniline), and 4,4'- Methylenebis(2-ethylaniline), 4,4'-methylenebis(2-chloroaniline), 4,4'-diamino-3,3'-dimethyldiphenylmethane, 2,5-diaminotoluene, 2,5-dimethyl-1,4-phenylenediamine, p-phenylenediamine, m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 4,4'-diaminodiphenylmethane, 4,4 '-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone Examples include bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 4,4'-bis(4-aminophenoxy)biphenyl, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-amino-3-chlorophenyl)fluorene, and 9,9-bis(4-amino-3-fluorophenyl)fluorene. Among these, aromatic diamine compounds having a structure in which a carbon atom with a hydrogen atom is directly bonded to a benzene ring, such as 2,2'-dimethylbenzidine and 9,9-bis(4-amino-3-methylphenyl)fluorene, are preferred. These aromatic diamine compounds may be used individually or in combination of two or more.

[0069] Furthermore, it is preferable that the aromatic diamine compound does not have a perfluoroalkyl portion or a polyfluoroalkyl portion.

[0070] Aromatic dicarboxylic acid compounds used in the synthesis of aromatic polyamide-imide resins include aromatic dicarboxylic acids or aromatic dicarboxylic acid derivatives. Examples of aromatic dicarboxylic acid derivatives include acid chlorides and esters of the aromatic dicarboxylic acid. Aromatic dicarboxylic acid compounds may be used individually or in combination of two or more.

[0071] When a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring exists in a unit derived from an aromatic dicarboxylic acid compound, it is even more preferable that it has a residue derived from an aromatic dicarboxylic acid compound represented by formula (2) above. In the reaction, the aromatic dicarboxylic acid compound may be a derivative of an acid chloride or the like. For an explanation of formula (2), refer to the explanation in the (Resin) section.

[0072] Specific examples of aromatic dicarboxylic acid compounds include, for example, 4,4'-methylenedibenzoic acid, 2-methylterephthalic acid, 2,5-dimethylterephthalic acid, 4,4'-oxybisbenzoic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 3,3'-biphenyldicarboxylic acid, and aromatic dicarboxylic acids and their derivatives (e.g., acid chlorides, acid anhydrides) in which two benzoic acids are linked by a single bond, -C(CH3)2-, -SO2-, or phenylene group. These aromatic dicarboxylic acid compounds may be used individually or in combination of two or more.

[0073] Among aromatic dicarboxylic acid compounds, terephthalic acid, 4,4'-oxybisbenzoic acid, or their derivatives are preferred, particularly terephthalic acid chloride (sometimes denoted as TPC) or 4,4'-oxybis(benzoyl chloride) (sometimes denoted as DEDC), as these improve the elongation at the breaking point and elastic modulus of the film.

[0074] Furthermore, it is preferable that the aromatic dicarboxylic acid compound does not have a perfluoroalkyl portion or a polyfluoroalkyl portion.

[0075] Aromatic tetracarboxylic acid compounds used in the synthesis of aromatic polyamide-imide resins include aromatic tetracarboxylic acids or aromatic tetracarboxylic acid derivatives. Aromatic tetracarboxylic acid derivatives include anhydrides of aromatic tetracarboxylic acids, preferably dianhydrides, acid chlorides, etc. These aromatic tetracarboxylic acid compounds may be used individually or in combination of two or more.

[0076] When a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring exists in a unit derived from an aromatic tetracarboxylic acid compound, it is even more preferable that it has a residue derived from an aromatic tetracarboxylic acid compound represented by formula (3) above. In the reaction, the aromatic tetracarboxylic acid compound may be a derivative of an acid anhydride, acid chloride, etc. For the explanation of formula (3), refer to the explanation in the (Resin) section.

[0077] Specific examples of aromatic tetracarboxylic acid compounds include non-condensed polycyclic aromatic tetracarboxylic dianhydrides, monocyclic aromatic tetracarboxylic dianhydrides, and condensed polycyclic aromatic tetracarboxylic dianhydrides. Examples of non-condensed polycyclic aromatic tetracarboxylic dianhydrides include 4,4'-(5-methylbiphenyltetracarboxylic dianhydride), 4,4'-oxydiphthalic acid dianhydride (sODPA), 3,4-oxydiphthalic acid dianhydride (aODPA), 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic acid dianhydride (BPADA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,2',3,3'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride (sBPDA), 2,2',3,3'-biphenyltetracarboxylic dianhydride (aBPDA), 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, and 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride. Examples include (BPAF), 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenoxyphenyl)propane dianhydride, 1,2-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,2-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, 4,4'-(p-phenylenedioxy)diphthalic acid dianhydride, and 4,4'-(m-phenylenedioxy)diphthalic acid dianhydride. Examples of monocyclic aromatic tetracarboxylic dianhydrides include 1,2,4,5-benzenetetracarboxylic dianhydride, while examples of condensed polycyclic aromatic tetracarboxylic dianhydrides include 2,3,6,7-naphthalenetetracarboxylic dianhydride.

[0078] Among aromatic tetracarboxylic acid compounds, it is preferable to use a combination of at least one selected from the group consisting of 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic acid dianhydride (BPADA), 3,4-oxydiphthalic acid dianhydride (aODPA), 4,4'-oxydiphthalic acid dianhydride (sODPA), 2,2',3,3'-biphenyltetracarboxylic acid dianhydride (aBPDA), and 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride (BPAF), in order to improve transparency without impairing various properties such as heat resistance and mechanical strength as a film.

[0079] Furthermore, it is preferable that the aromatic tetracarboxylic acid compound does not have a perfluoroalkyl moiety or a polyfluoroalkyl moiety.

[0080] In the synthesis of aromatic polyamide-imide resins, the molar ratio of monomer components (aromatic diamine compound: aromatic tetracarboxylic acid compound: aromatic dicarboxylic acid compound) is preferably 7:0.5 to 4:3 to 6.5, more preferably 7:1.5 to 3.5:3.5 to 5.5, and particularly preferably 7:2.5 to 3.5:3.5 to 4.5. According to the above-mentioned monomer component ratio, the molar ratio of imide structures to amide structures in the structure of the aromatic polyamide-imide resin is preferably 0.5 to 4:3 to 6.5, more preferably 1.5 to 3.5:3.5 to 5.5, and particularly preferably 2.5 to 3.5:3.5 to 4.5. By having the above-mentioned molar ratio of imide structures to amide structures, it is possible to achieve a good balance between excellent flexibility and high elasticity.

[0081] In the synthesis of aromatic polyamide-imide resins, the ring-closing reaction (imidization) of the imide precursor can be carried out by either thermal imidization, which involves adding an azeotropic solvent that forms an azeotrope with water (e.g., toluene, xylene, etc.) and heating, or chemical imidization, which uses a condensing agent and a reaction accelerator. However, chemical imidization is preferred because it is easier to maintain colorless transparency.

[0082] Examples of condensing agents used in chemical imidation include acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride, as well as phosphite esters such as triethyl phosphite, tributyl phosphite, dimethyl phosphite, diethyl phosphite, and triphenyl phosphite. These condensing agents may be used individually or in combination of two or more.

[0083] Examples of reaction accelerators used in chemical imidation include triethylamine, diisopropylethylamine, N-methylpiperidine, pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 3-ethylpyridine, 3,5-dimethylpyridine, 3,5-diethylpyridine, isoquinoline, imidazole, 1-methylimidazole, 2-methylimidazole, and 1,2-dimethylimidazole. These reaction accelerators may be used individually or in combination of two or more.

[0084] Organic solvents can be used in the synthesis of aromatic polyamide-imide resins. Such organic solvents are not particularly limited as long as they are inert to the reaction, and examples include N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, m-cresol, γ-butyrolactone, cyclopentanone, cyclohexanone, and tetrahydrofuran. These organic solvents may be used individually or in combination of two or more.

[0085] For the synthesis of aromatic polyamide-imide resins, the reaction conditions can be a temperature of 10 to 50°C and a time of 1 to 27 hours. Furthermore, to maintain colorlessness and transparency, it is preferable to synthesize the resins under a nitrogen atmosphere.

[0086] The weight-average molecular weight (Mw) of the aromatic polyamide-imide resin is preferably in the range of 50,000 to 1,000,000, more preferably in the range of 80,000 to 600,000, and even more preferably in the range of 120,000 to 300,000, from the viewpoint of improving the elastic modulus and elongation at the breaking point. In this specification, weight-average molecular weight (Mw) refers to the polystyrene-equivalent molecular weight measured by GPC (gel permeation chromatography).

[0087] [Aromatic polyamide resin] Aromatic polyamide resins are polyamide resins in which nitrogen atoms derived from amino groups are directly bonded to aromatic rings (having aromatic rings in the main chain). Aromatic polyamide resins are resins obtained, for example, by reacting aromatic diamine compounds and aromatic dicarboxylic acid compounds, which are monomer components. That is, aromatic polyamide resins are resins having an amide structure formed by the reaction of, for example, an aromatic diamine compound and an aromatic dicarboxylic acid compound. Furthermore, aromatic polyamide resins differ from the aforementioned polyamide-imide resins in that the structure that binds the constituent monomer components substantially does not have an imide structure. Moreover, it is preferable that the structure that binds the constituent monomer components of an aromatic polyamide resin substantially contains no structures other than amide structures and consists of amide structures. In this specification, the structure that binds the constituent monomer components does not include the structure in which the end-capturing agent described later binds to the polyamide resin.

[0088] The diamine compounds used in the synthesis of aromatic polyamide resins are the same as those used in the synthesis of polyamide-imide resins (including examples and preferred examples) as described above. The diamine compounds may be used individually or in combination of two or more.

[0089] The aromatic polyamide resin in the resin composition of this embodiment has a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring. In the structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring, it is preferable that the carbon atom having a hydrogen atom is directly bonded to a benzene ring to which a nitrogen atom derived from an amino group is bonded.

[0090] When a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring exists in a unit derived from an aromatic diamine compound, it is preferable that the carbon atom having a hydrogen atom in the structure in which the carbon atom having a hydrogen atom is directly bonded to a benzene ring to which a nitrogen atom derived from an amino group is bonded.

[0091] Furthermore, the aromatic polyamide resin in the resin composition of this embodiment is more preferably having residues derived from the aromatic diamine compound represented by formula (1) above. For a description of formula (1), refer to the explanation in the (Resin) section.

[0092] Specific examples of aromatic diamine compounds are the same as the specific examples and preferred examples described in the section on polyamide-imide resins. Aromatic diamine compounds may be used individually or in combination of two or more.

[0093] As the aromatic diamine compound represented by formula (1) above, 2,2'-dimethylbenzidine is preferred from the viewpoint of obtaining a polyamide resin with excellent transparency and mechanical strength. These may be used individually or in combination of two or more.

[0094] Furthermore, it is preferable that the aromatic diamine compound does not have a perfluoroalkyl portion or a polyfluoroalkyl portion.

[0095] When a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring exists in a unit derived from an aromatic dicarboxylic acid compound, it is even more preferable that it has a residue derived from an aromatic dicarboxylic acid compound represented by formula (2) above. In the reaction, the aromatic dicarboxylic acid compound may be a derivative of an acid chloride or the like. For an explanation of formula (2), refer to the explanation in the (Resin) section.

[0096] Specific examples of aromatic dicarboxylic acid compounds are the same as those described in the section on polyamide-imide resins. Aromatic dicarboxylic acid compounds may be used individually or in combination of two or more.

[0097] Among aromatic dicarboxylic acid compounds, terephthalic acid, 4,4'-oxybisbenzoic acid, or their derivatives, particularly terephthalic acid chloride (TPC) or 4,4'-oxybis(benzoyl chloride) (DEDC), are preferred because they improve the elongation at the breaking point and elastic modulus of the film. It is also preferable to use TPC and DEDC in combination as the aromatic dicarboxylic acid compound.

[0098] Aromatic polyamide resins can be produced by methods known for producing polyamides, such as solution polymerization, interfacial polymerization, melt polymerization, solid-phase polymerization, and precipitate polymerization. In particular, solution polymerization and interfacial polymerization are preferably used for producing aromatic polyamide resins.

[0099] Specifically, for example, aromatic polyamide resins can be synthesized by solution polymerization from aromatic diamine compounds and acid chlorides of aromatic dicarboxylic acids as aromatic dicarboxylic acid compounds. In this case, the reaction can be carried out in an aprotic organic polar solvent. Although hydrogen chloride is produced as a by-product in this reaction, it can be neutralized using inorganic neutralizing agents such as calcium hydroxide, calcium carbonate, and lithium carbonate, or organic neutralizing agents such as 1,2-butylene oxide, ethylene oxide, propylene oxide, ammonia, and pyridine.

[0100] Examples of aprotic organic polar solvents include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide; formamide solvents such as N,N-dimethylformamide and N,N-diethylformamide; acetamide solvents such as N,N-dimethylacetamide and N,N-diethylacetamide; pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone; hexamethylphosphoramide; and γ-butyrolactone. These aprotic organic polar solvents may be used individually or in combination of two or more. Aromatic hydrocarbons such as xylene and toluene can also be used. Furthermore, to promote the dissolution of polymers, a salt of an alkali metal or alkaline earth metal in an amount of 50% by mass or less may be added to the solvent.

[0101] When using aromatic polyamide resins, it is preferable to encapsulate the ends of the aromatic polyamide resin to improve the colorless transparency of the film. Examples of compounds used for encapsulating the ends of aromatic polyamide resins include acetyl chloride, benzoyl chloride, substituted benzoyl chloride, acetic anhydride, 5-norbornene-2,3-dicarboxylic acid anhydride, 4-ethynylaniline, 4-phenylethynylphthalic anhydride, and maleic anhydride.

[0102] For the synthesis of aromatic polyamide resins, the reaction conditions can be a temperature of 10 to 50°C and a time of 10 minutes to 27 hours. Furthermore, to maintain colorlessness and transparency, it is preferable to synthesize the resins under a nitrogen atmosphere.

[0103] Aromatic polyamide resins are preferably characterized by a number-average molecular weight (Mn) of 5,000 to 200,000, and more preferably 10,000 to 180,000, as this improves their mechanical properties.

[0104] The aromatic polyamide resin preferably has a weight-average molecular weight (Mw) of 120,000 or more and 300,000 or less. When the weight-average molecular weight (Mw) of the polyamide resin is 120,000 or more, the appearance and / or mechanical properties of the film can be further improved, and when it is 300,000 or less, the handling during the synthesis of the polyamide resin and the manufacture of the polyamide film can be further improved.

[0105] The aromatic polyamide resin preferably has a dispersion degree (Mw / Mn) of 1.0 or more and 20 or less, more preferably 1.0 or more and 15 or less, and even more preferably 1.0 or more and 4.0 or less.

[0106] The number-average molecular weight (Mn) and weight-average molecular weight (Mw) were measured by GPC (Gel Permeation Chromatography) and calculated using polystyrene equivalents.

[0107] [Aromatic polyimide resin] Aromatic polyimide resins are polyimide resins in which nitrogen atoms derived from amino groups are directly bonded to aromatic rings (having aromatic rings in the main chain). Aromatic polyimide resins are resins obtained, for example, by reacting aromatic diamine compounds and aromatic tetracarboxylic acid compounds, which are monomer components. That is, aromatic polyimide resins are resins having imide structures formed by the reaction of, for example, aromatic diamine compounds and aromatic tetracarboxylic acid compounds. Furthermore, aromatic polyimide resins differ from the aforementioned polyamide-imide resins in that the structures that bond the constituent monomer components substantially do not have amide structures. Moreover, it is preferable that aromatic polyimide resins consist of imide structures, and that the structures that bond the constituent monomer components substantially do not contain structures other than imide structures.

[0108] The aromatic polyimide resin in the resin composition of this embodiment has a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring. In the structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring, it is preferable that the carbon atom having a hydrogen atom is directly bonded to a benzene ring to which a nitrogen atom derived from an amino group is bonded.

[0109] When a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring exists in a unit derived from an aromatic diamine compound, it is preferable that the carbon atom having a hydrogen atom in the structure in which the carbon atom having a hydrogen atom is directly bonded to a benzene ring to which a nitrogen atom derived from an amino group is bonded.

[0110] Furthermore, the aromatic polyamide resin in the resin composition of this embodiment is more preferably having residues derived from the aromatic diamine compound represented by formula (1) above. For a description of formula (1), refer to the explanation in the (Resin) section.

[0111] Specific examples of aromatic diamine compounds are the same as those described in the section on polyamide-imide resins. Aromatic diamine compounds may be used individually or in combination of two or more.

[0112] As the aromatic diamine compound represented by formula (1) above, 2,2'-dimethylbenzidine is preferred from the viewpoint of obtaining a polyimide resin with excellent transparency and mechanical strength. These may be used individually or in combination of two or more.

[0113] Furthermore, it is preferable that the aromatic diamine compound does not have a perfluoroalkyl portion or a polyfluoroalkyl portion.

[0114] When a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring exists in a unit derived from an aromatic tetracarboxylic acid compound, it is even more preferable that it has a residue derived from an aromatic tetracarboxylic acid compound represented by formula (3) above. In the reaction, the aromatic tetracarboxylic acid compound may be a derivative of an acid anhydride, acid chloride, etc. For the explanation of formula (3), refer to the explanation in the (Resin) section.

[0115] Specific examples of aromatic tetracarboxylic acid compounds represented by formula (3) above, and aromatic dicarboxylic acid compounds other than those represented by formula (3) above, are the same as the specific examples described in the section on polyamide-imide resins. Aromatic dicarboxylic acid compounds may be used individually or in combination of two or more.

[0116] Furthermore, it is preferable that the aromatic tetracarboxylic acid compound does not have a perfluoroalkyl moiety or a polyfluoroalkyl moiety.

[0117] Aromatic polyimide resins can be produced by known methods for producing aromatic polyimides. For example, they can be produced by reacting an aromatic tetracarboxylic acid compound with an aromatic diamine compound to synthesize an imide precursor (polyamic acid resin), followed by a ring-closing reaction (imidization) of the imide precursor. The conditions for the ring-closing reaction are the same as those described above (including examples and preferred examples) for the ring-closing reaction of the imide precursor in the synthesis of aromatic polyamide-imide resins.

[0118] The weight-average molecular weight (Mw) of the aromatic polyimide resin is preferably in the range of 50,000 to 1,000,000, more preferably in the range of 80,000 to 600,000, and even more preferably in the range of 120,000 to 300,000, from the viewpoint of improving the elastic modulus and elongation at the breaking point. The weight-average molecular weight (Mw) is measured by GPC (gel permeation chromatography).

[0119] (Antioxidant) The resin composition of this embodiment contains one or more antioxidants selected from lactone-based antioxidants and antioxidants having a t-butyl group at one ortho position of an oxygen atom bonded to a benzene ring, and an alkyl group which may be substituted at the other ortho position (hereinafter also referred to as "specific antioxidants"). Antioxidants having a t-butyl group at one ortho position of an oxygen atom bonded to a benzene ring and an optionally substituted alkyl group at the other ortho position include phenolic antioxidants (A) (hereinafter sometimes simply referred to as "phenolic antioxidant (A)") and phosphite antioxidants (B) (hereinafter sometimes simply referred to as "phosphite antioxidant (B)"). The present inventors have found that, in the case of resins having a structure in which a carbon atom containing a hydrogen atom is directly bonded to a benzene ring, when a resin composition containing this resin is made into a film, the alkyl group may be oxidized and yellow (loss of colorlessness may occur). However, the resin composition of this embodiment aims to suppress the oxidation of the alkyl group by incorporating the above-mentioned antioxidant into the resin composition, thereby resolving the problem of yellowing when it is made into a film.

[0120] The specific antioxidant in the resin composition of this embodiment is preferably one or more selected from lactone-based antioxidants, phenol-based antioxidants (A), and phosphite-based antioxidants (B). Among these, phenol-based antioxidants (A) are preferred from the viewpoint of further suppressing yellowing.

[0121] As will be described later, since the three types of antioxidants described above each have different mechanisms for preventing oxidation, a synergistic effect can be expected by combining two or more antioxidants to further suppress yellowing. From the viewpoint of achieving a further suppression of yellowing, it is preferable to combine a lactone-based antioxidant and a phenol-based antioxidant (A). That is, it is preferable that the specific antioxidant in the resin composition of this embodiment includes a lactone-based antioxidant and a phenol-based antioxidant (A).

[0122] The content of the specific antioxidant in the resin composition of this embodiment is preferably 0.01 parts by mass or more and 20 parts by mass or less per 100 parts by mass of resin. When the content of the specific antioxidant is above the lower limit, yellowing of the film can be further suppressed when a film is formed using the resin composition of this embodiment, and the content of the specific antioxidant is more preferably 0.05 parts by mass or more, and even more preferably 0.10 parts by mass or more, per 100 parts by mass of resin. Furthermore, when the content of the specific antioxidant is below the upper limit, a film with excellent transparency can be obtained, and the content of the specific antioxidant is more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of resin. When the resin composition of this embodiment contains two or more specific antioxidants, it is preferable that the total content of the specific antioxidants is within the above range.

[0123] In the resin composition of this embodiment, the specific antioxidant preferably has a boiling point of 170°C or higher. Having a boiling point of 170°C or higher prevents the specific antioxidant from evaporating during heating or other processes when processing the resin composition.

[0124] The specific antioxidants in the resin composition of this embodiment will be described in more detail.

[0125] [Lactone-based antioxidants] Lactone-based antioxidants have the function of capturing carbon radicals, and through the exercise of this function, they can prevent oxidation. For example, lactone-based antioxidants capture carbon radicals that are generated from the bonding of carbon and hydrogen due to heat or light.

[0126] Lactone-based antioxidants refer to antioxidants having a lactone skeleton. Here, a lactone skeleton means a monocyclic or polycyclic atomic group containing a ring having -OC(=O)-. Lactone-based antioxidants that can be used are those described in Japanese Patent Publication No. 7-233160 and Japanese Patent Publication No. 7-247278.

[0127] In the resin composition of this embodiment, the lactone skeleton in the lactone-based antioxidant is preferably a 4- to 20-membered ring, and more preferably a 5- to 10-membered ring. The lactone skeleton may be a monocycle consisting only of a lactone ring, or it may have an aromatic or non-aromatic hydrocarbon ring or heterocycle fused to the lactone ring. In particular, the lactone skeleton is preferably one in which an aromatic hydrocarbon ring is fused to the lactone ring, and more preferably one in which a benzene ring is fused to the lactone ring.

[0128] A specific example of a lactone-based antioxidant is 3-(3,4-dimethylphenyl)-5,7-di-tert-butylbenzofuran-2(3H)-one. Furthermore, commercially available lactone-based antioxidants include Irganox HP-136 (registered trademark, manufactured by CIBA SPECIALTY CHEMICALS).

[0129] When the resin composition contains a lactone-based antioxidant, the content of the lactone-based antioxidant is preferably 0.01 parts by mass or more and 20 parts by mass per 100 parts by mass of resin. By having a lactone-based antioxidant content within this range, the yellowing-suppressing effect of the lactone-based antioxidant can be fully exhibited. More preferably, the content of the lactone-based antioxidant is 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, per 100 parts by mass of resin. Furthermore, the content of the lactone-based antioxidant is more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of resin.

[0130] Lactone-based antioxidants may be used individually or in combination of two or more types.

[0131] [An antioxidant having a t-butyl group at one ortho position of an oxygen atom bonded to a benzene ring, and an optionally substituted alkyl group at the other ortho position.] An antioxidant having a t-butyl group at one ortho position of an oxygen atom bonded to a benzene ring, and an optionally substituted alkyl group at the other ortho position, may have a substructure represented by the following formula (4). [ka] During the ceremony, R 10 This represents an alkyl group that may be substituted, * represents a coupling.

[0132] R 10Regarding this, the alkyl group may be linear or branched, and examples include alkyl groups having 1 to 6 carbon atoms, such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, and 1,2-dimethylpropyl group. Among these, alkyl groups having 1 to 4 carbon atoms are preferred, and methyl group or t-butyl group are more preferred. Furthermore, from the viewpoint of further suppressing yellowing, groups with greater steric hindrance are preferred, and t-butyl group is preferred.

[0133] R 10 The alkyl group in may be substituted, and the substituents that substitute for the alkyl group are not limited, but include, for example, halogen atoms and optionally substituted aryl groups. Also, R 10 The alkyl group in the above formula (4) may form a ring structure with the -O- group via substituents.

[0134] Furthermore, antioxidants having a t-butyl group at one ortho position of an oxygen atom bonded to a benzene ring, and an optionally substituted alkyl group at the other ortho position, shall not include antioxidants containing a lactone skeleton.

[0135] -Phenol-based antioxidant (A)- In the case of a phenolic antioxidant (A), the oxygen atom bonded to the benzene ring is bonded to hydrogen to form a hydroxyl group. That is, phenolic antioxidant (A) has a t-butyl group at one ortho position of the hydroxyl group bonded to the benzene ring, and an alkyl group which may be substituted at the other ortho position.

[0136] Phenolic antioxidants capture peroxyl radicals generated by the reaction of carbon radicals with oxygen, and donate hydrogen to these peroxyl radicals to convert them into hydroperoxides. This prevents chain reactions caused by peroxyl radicals and suppresses oxidation.

[0137] The phenolic antioxidant (A) preferably has a substructure represented by the following formula (4A). [ka] During the ceremony, R 10 This is synonymous with formula (4), and the examples and preferred examples apply. * represents a coupling.

[0138] Examples of phenolic antioxidants (A) include 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyl]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5,5]undecane, 2,6-di-tert-butyl-p-cresol (BHT), 2,4,6-tri-tert-butylphenol, n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol)propionate, 4-hydroxy-methyl-2,6-di-tert-butylphenol, 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol), and 2,2'-methylene-bis-(4-ethyl-6-tert-butylphenol). Examples include tris(methylphenol), 4,4'-methylene-bis-(2,6-di-tert-butylphenol), 2,6-bis(2'-hydrooxy-3'-tert-butyl-5'-methylmethylbenzyl)4-methylphenol, 1,3,5-tris-methyl-2,4,6-tris(3,5-di-tert-butyl-4-hydrooxybenzyl)benzene, tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydrooxyphenyl)propionate]methane, tris(3,5-di-tert-butyl-4-hydrooxyphenyl)isocyanurate, and tris[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl-oxyethyl]isocyanate.

[0139] The phenolic antioxidant (A) may be a commercially available product, such as AO-20, AO-50, AO-60, AO-80, IRGANOX1098, IRGANOX1222, IRGANOX1330, etc.

[0140] When the resin composition contains a phenolic antioxidant (A), the content of the phenolic antioxidant (A) can be 0.01 parts by mass or more and 20 parts by mass or less per 100 parts by mass of resin. By having a phenolic antioxidant (A) content within the above range, the yellowing-suppressing effect of the phenolic antioxidant (A) can be fully exhibited. The content of the phenolic antioxidant (A) is more preferably 0.05 parts by mass or more, and even more preferably 0.10 parts by mass or more, per 100 parts by mass of resin. Furthermore, the content of the phenolic antioxidant (A) is more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of resin.

[0141] The phenolic antioxidant (A) may be used alone or in combination of two or more types.

[0142] -Phosphate-based antioxidant (B)- In the case of a phosphite-based antioxidant (B), the oxygen atom bonded to the benzene ring is bonded to a phosphorus atom (P). More specifically, the oxygen atom bonded to the benzene ring is an oxygen atom derived from the phosphite.

[0143] Phosphate-based antioxidants inhibit oxidation by decomposing the resulting hydroperoxides.

[0144] The phosphite-based antioxidant (B) preferably has a substructure represented by the following general formula (4B). [ka] During the ceremony, R 10 This is synonymous with formula (4), and the examples and preferred examples apply. * represents a coupling.

[0145] In the above equation (4B), R 10The alkyl group may form a ring with the -O- bonded to the phosphorus atom in formula (4B) via substituents.

[0146] Examples of phosphite antioxidants (B) include 3,9-bis(2,4-di-tert-butylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol-di-phosphite, and 2,2'-methylenebis(4,6-di-tert-butylphenyl)octylphosphite.

[0147] The phosphite antioxidant (B) may be a commercially available product, such as HP-10 or PEP-36.

[0148] When the resin composition contains a phosphite-based antioxidant (B), the content of the phosphite-based antioxidant (B) can be 0.01 parts by mass or more and 20 parts by mass or less per 100 parts by mass of resin. By having a phosphite-based antioxidant (B) content within the above range, the yellowing-suppressing effect of the phosphite-based antioxidant (B) can be fully exhibited. The content of the phosphite-based antioxidant (B) is more preferably 0.05 parts by mass or more, and even more preferably 0.10 parts by mass or more, per 100 parts by mass of resin. Furthermore, the content of the phosphite-based antioxidant (B) is more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of resin.

[0149] The phosphite antioxidant (B) may be used alone or in combination of two or more types.

[0150] [Other antioxidants] The resin composition of this embodiment may contain antioxidants other than the specific antioxidant (hereinafter also referred to as "other antioxidants"), to the extent that they do not impede the effects of the present invention. Other antioxidants include, for example, phenolic antioxidants other than phenolic antioxidant (A), phosphite antioxidants other than phosphite antioxidant (B), sulfur-based antioxidants, amine-based antioxidants, and the like.

[0151] Examples of phenolic antioxidants other than phenolic antioxidant (A) include styrenephenol, 2,5-di-tert-butyl-hydroquinone, cyclohexylphenol, butylhydroxyanisole, 4,4′-iso-propylenebisphenol, 4,4′-butylidene-bis(3-methyl-6-tert-butylphenol), 1,1-bis-(4-hydrooxyphenyl)cyclohexane, 1,1,3-tris(2-methyl-4-hydrooxy-5-tert-butylphenyl)butane, 4,4′-thiobis(3-methyl-6-tert-butylphenol), 2,2′-thiobis(4-methyl-6-tert-butylphenol), 4,4′-thiobis(2-methyl-6-tert-butylphenol), and N,N′-hexamethylenebis(3,5-di-tert-butylphenol-4-hydroxycinnamamide).

[0152] Phosphate antioxidants other than phosphate antioxidant (B) include 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triphenyl phosphite, 2-ethylhexyl phosphate, dilauryl phosphite, tri-iso-octyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, trilauryl phosphite, trilauryl-di-thiophosphite, trilauryl-tri-thiophosphite, trisnonylphenyl phosphite, distearyl pentaerythritol diphosphite, tris(mononylphenyl) phosphite, tris(dinonylphenyl) phosphite, trioctadecyl phosphite, and 1,1,3-tris(2-methyl-di-tridecyl phosphate). Examples include ito-5-tert-butylphenyl)butane, 4,4′-butylidene-bis(3-methyl-6-tert-butyl)tridecyl phosphite, 4,4′-butylidene-bis(3-methyl-6-tert-butyl-di-tridecyl) phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol-di-phosphite, tetrakis(2,4-di-tert-butylphenyl)4,4′-bisphenylenediphosphite, distearylpentaerythritol diphosphite, tridecyl phosphite, tristearyl phosphite, sorbitol-tris-phosphite-distearyl-mono-C30-diol ester, and bis(2,4,6-tri-tert-butylphenyl)pentaerythritol diphosphite.

[0153] Examples of amine-based antioxidants include 4,4′-bis(α,α-dimethylbenzyl)diphenylamine, phenyl-α-naphthylamine, phenyl-β-naphthylamine, N,N′-diphenyl-p-phenylenediamine, N,N′-di-β-naphthyl-p-phenylenediamine, N-cyclohexyl-N′-phenyl-p-phenylenediamine, N-phenyl-N′-isopropyl-p-phenylenediamine, aldol-α-naphthylamine, polymers of 2,2,4-trimethyl-1,2-dihydroquinone, and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline.

[0154] Examples of sulfur-based antioxidants include thiobis(β-naphthol), thiobis(N-phenyl-β-naphthylamine), 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, dodecyl mercaptan, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, nickel dibutyldithiocarbamate, nickel isopropylxanthate, dilauryl thiodipropionate, and distearyl thiodipropionate.

[0155] (Phosphate ester compounds or phosphonic acid compounds) The resin composition of this embodiment may contain one or more compounds selected from phosphate ester compounds and phosphonic acid compounds (hereinafter sometimes collectively referred to as "phosphorus compounds"). By containing phosphorus compounds in the resin composition, the amount of organic solvent remaining in the film can be reduced, thus suppressing yellowing caused by the oxidation of organic solvents. From the viewpoint of suppressing yellowing, the molecular weight of the phosphorus compound is preferably 300 or less, more preferably 250 or less, and even more preferably 200 or less. Within this range, the volatility of the phosphorus compound increases, thus reducing the amount of phosphorus compound remaining in the film using the resin composition. The phosphorus compound may be a single compound or a combination of two or more compounds.

[0156] When phosphorus compounds are used in combination with the specific antioxidants mentioned above, they are expected to further suppress yellowing of the film when the resin composition is used to form a film. Among the specific antioxidants, it is preferable that phosphorus compounds are included in the resin composition in combination with at least one specific antioxidant selected from lactone-based antioxidants and phenol-based antioxidants (A). Furthermore, from the viewpoint of further suppressing yellowing of the film, it is even more preferable that phosphorus compounds are included in addition to lactone-based antioxidants and phenol-based antioxidants (A).

[0157] In the present invention, the phosphorus compound is different from the phosphite antioxidant in that it has a phosphate ester skeleton or a phosphonic acid skeleton.

[0158] As the phosphate ester compound, a primary phosphate ester compound or a condensed phosphate ester compound is preferable.

[0159] Examples of the phosphorus compound include a phosphonic acid compound represented by the following formula (5A), a primary phosphate ester compound represented by the following formula (5B), and a condensed phosphate ester compound represented by the following formula (5C). More specifically, it is preferable that the phosphonic acid compound is a phosphonic acid compound represented by the following formula (5A), and the phosphate ester compound is a primary phosphate ester compound represented by the following formula (5B) or a condensed phosphate ester represented by the following formula (5C). [Chemical formula] In the formula, R 21 and R 22 are each independently a hydrogen atom, an alkyl group or an aryl group, and the alkyl group and the aryl group may have a substituent. R 23 is an alkyl group or an aryl group, and the alkyl group and the aryl group may have a substituent. [Chemical formula] In the formula, R 24 ~R 26 are each independently a hydrogen atom, an alkyl group or an aryl group, and the alkyl group and the aryl group may have a substituent, provided that not all of R 24 ~R 26 are hydrogen atoms. [Chemical formula] In the general formula (5C), R 27 and R 28is, independently, an alkyl group or an aryl group which may have a substituent, Z is a divalent organic group containing at least one aromatic ring, and n is an integer of 1 or more], and is represented by. The condensed phosphate ester may be used alone or in combination of two or more.

[0160] In the above general formula (5C), n is preferably 1. Further, in the above general formula (5C), R 27 and R 28 are preferably an aryl group and more preferably a phenyl group from the viewpoint of obtaining a higher desired effect. Further, in the general formula (5C), Z preferably contains one or two aromatic rings from the viewpoint of obtaining a higher desired effect.

[0161] Regarding R 21 and R 22 in the above formula (5A), the alkyl group may be either linear or branched, and examples thereof include alkyl groups having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a tert-pentyl group, a neopentyl group, a 1,2-dimethylpropyl group, and the like. Among them, from the point of obtaining an even higher desired effect, an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group is more preferable.

[0162] Regarding R 21 and R 22 in the above formula (5A), examples of the aryl group include aryl groups having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, and the like. Among them, a phenyl group is preferable.

[0163] The above alkyl group and aryl group may have a substituent, and the substituent is not particularly limited, and examples thereof include an alkenyl group, an aryl group, a halogen atom, and the like.

[0164] From the point of obtaining a higher desired effect, R 21 and R 22Each of these is preferably an alkyl group, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably both are methyl groups.

[0165] R in the above formula (5A) 23 Regarding alkyl groups, aryl groups and substituents, the above R 21 and R 22 Examples and preferred examples relating to this apply. R 23 From the viewpoint of obtaining a higher desired effect, it is preferable that the group be an aryl group, and more preferably a phenyl group.

[0166] Examples of phosphonic acid compounds represented by formula (5A) include dimethyl phenylphosphonate.

[0167] With respect to the above formula (5B), the alkyl group, aryl group and substituent are as follows: 21 and R 22 Examples and preferred examples relating to this apply. From the perspective of obtaining a higher desired effect, R 24 ~R 26 Each of these groups is preferably an alkyl group, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group or an ethyl group. A phenyl group can also be preferably used.

[0168] Examples of orthophosphate ester compounds represented by formula (5B) include trimethyl phosphate, triethyl phosphate (TEP), triphenyl phosphate, and the like.

[0169] Examples of condensed phosphate ester compounds represented by formula (5C) include resorcinol bis(diphenyl phosphate) and bisphenol A bis(diphenyl phosphate). Commercially available examples of condensed phosphate ester compounds represented by formula (5C) include FP-900L, PFR, and FP-600 from ADEKA Corporation's ADEKA Stab series.

[0170] In this embodiment, the resin composition preferably contains a phosphorus compound in an amount of 1 to 25 parts by mass per 100 parts by mass of resin. Within this range, the effects of including the phosphorus compound can be fully enjoyed. The phosphorus compound content is more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, even more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. Furthermore, when producing a film using a resin composition, phosphorus compounds may volatilize during the drying process. For films using a resin composition, the phosphorus compound content relative to the total mass of the film can be measured using thermogravimetric analysis (TGA).

[0171] (Filler) The resin composition of this embodiment may contain a filler. The shape of the filler is not particularly limited and can be fibrous, spherical, plate-shaped, cylindrical, prismatic, flaky, or irregularly shaped. Among these, the shape of the filler is preferably fibrous. That is, the filler is preferably fibrous. In this case, by arranging each fibrous filler in a lattice pattern in the resin composition, it is thought that the effect of increasing elasticity can be imparted while suppressing discoloration, cloudiness, and a decrease in flexibility. Furthermore, compared to spherical or irregularly shaped fillers, fibrous fillers can provide an excellent anti-blocking effect without impairing light transmittance. Specifically, when the resin films of the present invention are stacked or stored in a roll, the fibrous fillers described above can suppress adhesion (blocking) between the resin films, improving storage stability and workability. Furthermore, "fibrous" refers to a shape with an aspect ratio (filler length / filler diameter) of 5 or more.

[0172] The fibrous filler preferably has an average fiber diameter of 1 to 30 nm and an average fiber length of 100 to 4,000 nm. When such fibrous fillers are dispersed, the fibrous fillers are arranged in a lattice pattern in the resin composition, which further enhances the effects of suppressing the reduction in color, turbidity, and flexibility, as well as the effect of increasing elasticity. Similarly, the average fiber diameter of the fibrous filler is more preferably 2 nm or more, even more preferably 3 nm or more, even more preferably 25 nm or less, and even more preferably 20 nm or less. Similarly, the average fiber length of the fibrous filler is more preferably 300 nm or more, even more preferably 500 nm or more, even more preferably 3,000 nm or less, and even more preferably 2,000 nm or less.

[0173] The "average fiber diameter" and "average fiber length" are measured by dissolving the resin composition or resin film in a good solvent for the resin constituting the resin (e.g., methyl isobutyl ketone (MIBK) or dimethylacetamide (DMAc)) and diluting it 10,000 times, dropping one drop onto a cover glass (cover glass trophy, manufactured by Matsunami Glass Co., Ltd.), drying at 50°C, and then observing it with a scanning probe microscope (e.g., topographic observation image using Hitachi High-Tech AFM5000II). Furthermore, the fibrous filler to be measured may be a single fiber or a bundle of multiple single fibers, as long as it is visible as a single fiber in the scanning probe microscope image. The number-average length of the diameter in the short-side direction of 200 arbitrarily selected fibrous fillers in the scanning probe microscope image is defined as the "average fiber diameter," and the number-average length of the diameter in the long-side direction is defined as the "average fiber length."

[0174] Fibrous fillers can be mixed with a predetermined resin in powder or dispersion (sol) form, stirred, and kneaded as needed to adjust the dispersion state in the resin composition or resin film, i.e., the "average fiber diameter" and "average fiber length." For example, stirring or kneading can be performed using stirrers such as dissolvers or butterfly mixers, or kneaders such as roll mills or bead mills. These can be adjusted by various conditions such as the rotation speed of the stirrer / kneader, the shape of the stirring blades / kneading device, the stirring / kneading time, the stirring / kneading temperature, the bead filling rate, and the roll spacing.

[0175] Fibrous fillers can be surface-treated or used as a dispersion (sol) in an organic solvent. In this case, the dispersion state in the resin composition can be stabilized. In particular, by adjusting the dispersion state of the fibrous filler in the dispersion (sol) to be the same as the dispersion state of the fibrous filler in the resin composition, i.e., the "average fiber diameter" and "average fiber length," the solution (dispersion) and, consequently, the resin film can be manufactured with high productivity.

[0176] The surface treatment method for the fibrous filler is not particularly limited, and examples include surface treatment using coupling agents such as silane-based, titanate-based, aluminate-based, and zircoaluminate-based agents. Furthermore, the method for preparing the dispersion of the fibrous filler is not particularly limited, and examples include the method for preparing a dispersion treated with an organic sulfonic acid as disclosed in Japanese Patent Application Publication No. 2008-31010.

[0177] The material of the fibrous filler is not particularly limited, but examples include silica, titanium oxide, alumina (including alumina hydrate), silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, etc. Examples of alumina hydrate include boehmite and pseudo-boehmite. These may be used individually or in combination of two or more. Among these, alumina (including alumina hydrate) is preferred as the material of the fibrous filler, boehmite or pseudo-boehmite is more preferred, and pseudo-boehmite is even more preferred. That is, the fibrous filler is preferably a fibrous alumina filler, more preferably a boehmite-type or pseudo-boehmite-type fibrous alumina filler, and even more preferably a pseudo-boehmite-type fibrous alumina filler. In this case, the mechanical and optical properties of the resin film can be further improved.

[0178] In this embodiment, the resin composition preferably contains a filler of 1 to 40 parts by mass per 100 parts by mass of resin. If the filler content is within this range, it is possible to achieve high elasticity while maintaining the various properties required of the film. Similarly, the filler content per 100 parts by mass is more preferably 5 parts by mass or more, and even more preferably 30 parts by mass or less.

[0179] (Other ingredients) The resin composition of this embodiment may contain other components in addition to the above components, as long as they do not impair the effects of the present invention. Other components can be used as appropriate depending on the desired properties, and examples include other resins other than those described above, solvents, leveling agents, dispersants, surfactants, retardation modifiers, UV inhibitors, light stabilizers, plasticizers, waxes, pigments, dyes, foaming agents, defoaming agents, dehydrating agents, antistatic agents, antibacterial agents, antifungal agents, bluing agents, pH adjusters, crosslinking agents, lubricants, and the like.

[0180] [Method for producing resin compositions] The resin composition of this embodiment can be prepared by mixing essential and optional components. The mixing method is not particularly limited, and conventional methods can be used. The essential and optional components may be blended in a solvent and varnished.

[0181] <film> The film of this embodiment is characterized by being made of the resin composition described above. Because it is made from the resin composition described above, the film of this embodiment has good colorlessness. (Manufacturing method) The resin composition of this embodiment can be used to produce a film. For example, a film can be produced by applying the varnish of the resin composition onto a support and drying it as needed.

[0182] The support is not particularly limited and includes, for example, polyester films such as polyethylene terephthalate or polyethylene naphthalate, stainless steel belts, polyimide films, etc. The support can be peeled off from the film as appropriate. The support may be treated with a release agent to facilitate the peeling of the film.

[0183] The means for applying varnish to the support are not particularly limited, and conventionally known methods can be applied, such as the dip coat method, flow coat method, roll coat method, bar coater method, blade coater method, screen printing method, curtain coat method, and spray coat method.

[0184] After applying the varnish to the support, it is dried as needed. The drying method is not particularly limited, and conventionally known methods can be applied. The drying temperature can be adjusted based on the boiling point of the solvent used in the varnish. Drying can be carried out in two stages. For example, it is preferable to perform primary drying at 90-150°C for 1-60 minutes, followed by secondary drying at 180-250°C for 1-60 minutes. Primary and secondary drying may be carried out under a nitrogen atmosphere.

[0185] (film thickness) The film thickness of the film in this embodiment is not particularly limited and can be selected as appropriate. The film in this embodiment can have good optical properties even with a film thickness of 30 μm or more. Furthermore, the film thickness is preferably 100 μm or less, and more preferably 80 μm or less. The film thickness can be adjusted by the amount of varnish applied.

[0186] (YI value) In this embodiment, the film preferably has a YI value (yellowness) of 10.0 or less at a film thickness of 55 μm, more preferably 7.0 or less, and even more preferably 5.0 or less. The lower limit of YI is not particularly limited and can be, for example, -1.0 or greater. The YI value (yellowness) of the film in this embodiment is calculated in accordance with ASTM D1925 by measuring the transmittance for light from 300 to 800 nm using a UV-Vis-Near-Infrared spectrophotometer with a C light source and a 2-degree field of view, determining the tristimulus values ​​(X, Y, Z), and then calculating the value based on the formula YI = 100 × (1.28X - 1.06Z) / Y.

[0187] (Uses of film) The film of this embodiment can be used in a wide range of applications, such as packaging films and various optical films, but because of its excellent colorlessness, it is particularly suitable for use as a display component. Examples of display components include organic EL displays, flexible substrates, flexible panels, liquid crystal display devices, touch panels, cover windows, and surface protective films.

[0188] <Flexible Display> The flexible display of this embodiment is characterized by including the above-described film. Because such a flexible display uses the above-described film, it exhibits good colorlessness.

[0189] For example, the film of the present embodiment can be used as a part of a layer of a flexible display, such as a cover window, and adhered to other layers (such as an impact absorption layer, a splash prevention layer, etc.) to fabricate a flexible display. Such a flexible display can be used in flexible devices such as a foldable mobile phone or tablet, and a deformable solar cell panel, etc.

Examples

[0190] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples at all.

[0191] <Measurement method> Various measurements on the polyamide resin and polyamide film fabricated in the examples were carried out according to the following procedures.

[0192] (1) Film thickness The film thickness was measured using a micrometer (manufactured by Mitutoyo Corporation).

[0193] (2) Total light transmittance, and haze For the total light transmittance and haze of the film, the film of each example was cut into a size of 30 mm × 30 mm to prepare an evaluation sample, and each evaluation sample was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., NDH 7000 II) in accordance with ASTM D1003. Note that the larger the value of the total light transmittance, the better the transparency. Also, the smaller the value of the haze, the better the transparency.

[0194] (3) YI value (degree of yellowing) Each film was cut into a size of 30 mm × 30 mm, and the YI value of each film was measured using a spectrocolorimeter (manufactured by Konica Minolta Sensing, Inc., CM-5) in accordance with ASTM D1925. For comparison between the films, the measured YI value converted to a film thickness of 55 μm was taken as the YI value @ 55 μm for each example. The closer the YI value @ 55 μm is to 0, the better the colorlessness.

[0195] (4) Number-average molecular weight (Mn) and weight-average molecular weight (Mw) The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the polyamide resin were measured using the GL7700 from GL Sciences. Column: TSKgelαM (manufactured by Tosoh Corporation) Column temperature: 40℃ Eluent: NMP solution containing 100 mmol / L H3PO4 (using an 85% aqueous solution of H3PO4 as the raw material) and 10 mmol / L LiBr. Calibration curve: Standard polystyrene Column flow rate: 0.7 mL / min The number-average molecular weight (Mn) and weight-average molecular weight (Mw) are expressed in terms of polystyrene equivalents.

[0196] <Composition> The resins, antioxidants, and phosphorus compounds used in each example and comparative example are as follows.

[0197] (resin) Polyamide resin 1 (PA1): A polyamide resin synthesized using 2,2'-dimethylbenzidine as the aromatic diamine compound and 4,4'-oxybis(benzoyl chloride) (DEDC) as the aromatic dicarboxylic acid compound, synthesized by the method described below. Polyamide resin 2 (PA2): A polyamide resin synthesized using 9,9-bis(4-amino-3-methylphenyl)fluorene as the aromatic diamine compound and 4,4'-oxybis(benzoyl chloride) (DEDC) as the aromatic dicarboxylic acid compound, synthesized by the method described below. Polyamide-imide resin (PAI): A polyamide-imide resin synthesized using 2,2'-dimethylbenzidine as the aromatic diamine compound, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane anhydride (BPADA) as the aromatic tetracarboxylic acid compound, and 4,4'-oxybis(benzoyl chloride) (DEDC) as the aromatic dicarboxylic acid compound, synthesized by the method described below.

[0198] (Antioxidant) Lactone-based antioxidant: 5,7-di-tert-butyl-3-(3,4-dimethylphenyl)benzofuran-2(3H)-one (manufactured by Tokyo Chemical Industry Co., Ltd.), referred to as "lactone-based" in the table. [ka] Phenolic antioxidant 1: 2,6-di-tert-butyl-p-cresol (BHT) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), referred to as "Phenol 1" in the table. Phenolic antioxidant 2: Manufactured by ADEKA Corporation, product name "ADEKA Stab AO-50", referred to as "Phenolic 2" in the table. [ka] Phenolic antioxidant 3: Manufactured by ADEKA Corporation, product name "ADEKA Stab AO-60", referred to as "Phenolic 3" in the table. [ka] Phenolic antioxidant 4: Manufactured by ADEKA Corporation, product name "ADEKA Stab AO-80", referred to as "Phenolic 4" in the table. [ka] Phenolic antioxidant 5: Manufactured by Sumitomo Chemical Co., Ltd., product name "SumiLizer GP", referred to as "Phenolic 5" in the table. [ka] Phenolic antioxidant 2: Manufactured by ADEKA Corporation, product name "ADEKA Stab AO-30", referred to as "Phenol-based 6" in the table, not applicable to phenolic antioxidant (A). [ka] Phenolic antioxidant 3: Manufactured by ADEKA Corporation, product name "ADEKA Stab AO-40", referred to as "Phenol-based 7" in the table, not applicable to phenolic antioxidant (A).

Chem.

Chem.

Chem.

[0199] (Phosphorus compound) Phosphorus compound 1: Triethyl phosphate (TEP), manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight = 182 Phosphorus compound 2: Dimethyl phenylphosphonate (PPADM), manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight = 186

[0200] <Synthesis of polyamide resin 1> A 100 mL reactor was filled with 66.7 g of N,N-dimethylacetamide (DMAc), and 4.31 g (20.3 mmol) of 2,2'-dimethylbenzidine and 3.22 g (44.6 mmol) of 1,2-butylene oxide were added. Then, 5.96 g (20.1 mmol) of 4,4'-oxybis(benzoyl chloride) (DEDC) was added to this solution of 2,2'-dimethylbenzidine, and the mixture was stirred at 30 °C for 2 hours to react. Thereafter, 0.16 g (2.0 mmol) of acetyl chloride was added to this solution, and the mixture was stirred at 30 °C for 30 minutes to react, obtaining a solution containing a polymer (polyamide resin 1) having an amide structure.

[0201] <Synthesis of Polyamide Resin 2> 40.4 g of N,N-dimethylacetamide (DMAc) was packed into a 100 mL reactor, and 4.02 g (10.7 mmol) of 9,9-bis(4-amino-3-methylphenyl)fluorene and 1.69 g (23.5 mmol) of 1,2-butylene oxide were added. Next, 3.15 g (10.7 mmol) of 4,4'-oxybis(benzoyl chloride) (DEDC) was added to this 9,9-bis(4-amino-3-methylphenyl)fluorene solution, and the mixture was stirred at 30°C for 2 hours to allow the reaction to proceed. Subsequently, 0.096 g (1.1 mmol) of acetyl chloride was added to this solution, and the mixture was stirred at 30°C for 30 minutes to obtain a solution containing a polymer having an amide structure (polyamide resin 2).

[0202] <Synthesis of polyamide-imide resin> 62.4 g of N,N-dimethylacetamide (DMAc) was packed into a 100 mL reactor, and 2.74 g (12.9 mmol) of 2,2'-dimethylbenzidine was added. Next, 2.88 g (5.5 mmol) of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) was added to this 2,2'-dimethylbenzidine solution, and the mixture was stirred at 30°C for 2 hours to obtain a solution containing a polymer having an imide precursor structure. Subsequently, 1.17 g (16.2 mmol) of 1,2-butylene oxide was added to this solution. Next, 2.14 g (7.3 mmol) of 4,4'-oxybis(benzoyl chloride) (DEDC) was added, and the mixture was stirred at 30°C for 1.5 hours to obtain a solution containing a copolymer having both an imide precursor structure and an amide structure. Subsequently, 4.90 g of pyridine and 6.34 g of acetic anhydride were added and the mixture was stirred at 20-30°C for 8 hours to obtain a polyamide-imide solution. Further, 99 g of DMAc was added and the mixture was stirred until homogeneous. This solution was then gradually added to a container with 4 L of methanol to allow precipitation. Next, the precipitated solid was filtered and ground, and then dried under vacuum at 80°C for 18 hours to obtain 7.0 g of solid powder polyamide-imide copolymer (polyamide-imide resin).

[0203] <Film Production> For each example and comparative example, a film was prepared using the following method. According to the formulations shown in Tables 1 to 3, powdered resin (polyamide resin 1, polyamide resin 2, or polyamide-imide resin), an antioxidant, and a phosphorus compound were dissolved in a solvent (dimethylacetamide, DMAc) and homogenized to prepare a solution for film manufacturing. Next, this solution was applied to a glass substrate using a table coater (AFA-standard, manufactured by Cortec Co., Ltd.) to a thickness of approximately 50 μm after drying. Then, it was dried using an oven (Fine Oven DH612, manufactured by Yamato Scientific Co., Ltd.) to form a film made of the resin composition. The drying conditions were a two-stage drying process: 20 minutes at 120°C followed by 20 minutes at 220°C. When incorporating fillers into the film, a dispersant (phenylphosphonic acid) was dissolved in the above solvent in addition to the resin powder and antioxidant. Then, an alumina slurry (manufactured by Kawaken Fine Chemicals, alumina filler (pseudoboehmite filler), fiber diameter 5 nm, fiber length 800 nm, N,N-dimethylacetamide (DMAc) dispersion, solid content concentration 10 parts by mass) was added and adjusted to a solid content concentration of 13% by mass. After that, the slurry was dispersed and homogenized to prepare a solution for film manufacturing.

[0204] The film was measured using the measurement method described above. The results are shown in Tables 1 to 3.

[0205] [Table 1]

[0206] [Table 2]

[0207] [Table 3]

[0208] Tables 1 to 3 show that films made using resin compositions containing resins that do not fall under the category of PFAS and specific antioxidants exhibit good colorlessness. In other words, it is possible to produce films with good colorlessness using resin compositions containing resins that do not fall under the category of PFAS and specific antioxidants. [Industrial applicability]

[0209] According to the present invention, it is possible to provide a resin composition that can produce a film with good colorlessness using monomers that do not fall under the category of PFAS. Furthermore, according to the present invention, it is possible to provide a film using such a resin composition, and a flexible display using the film.

Claims

1. One or more resins selected from aromatic polyimide resins, aromatic polyamideimide resins, and aromatic polyamide resins, and The antioxidant comprises at least one antioxidant selected from lactone-based antioxidants and antioxidants having a t-butyl group at one ortho position of an oxygen atom bonded to a benzene ring and an alkyl group which may be substituted at the other ortho position. The resin has a structure in which a carbon atom having a hydrogen atom is directly bonded to a benzene ring. Resin composition.

2. The resin composition according to claim 1, wherein the resin does not have a perfluoroalkyl portion and a polyfluoroalkyl portion.

3. The resin composition according to claim 1, wherein the antioxidant having a t-butyl group at one ortho position of the oxygen atom bonded to the benzene ring and an optionally substituted alkyl group at the other ortho position is a phenolic antioxidant or a phosphite antioxidant.

4. The resin composition according to claim 1, wherein the content of the antioxidant is 0.01 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the resin.

5. The resin composition according to claim 1, wherein a nitrogen atom derived from an amino group is bonded to a benzene ring to which the carbon atom having the hydrogen atom is directly bonded.

6. The resin film according to claim 5, wherein the resin has a residue derived from an aromatic diamine compound represented by the following formula (1). 【Chemistry 1】 During the ceremony, n is either 0 or 1, R １ and R ２ are each independently, -CH ３ , -CH ２ R ａ , -CHR ｂ R ｃ , -CR ｄ R ｅ R ｆ , or a halogen atom, R ａ ~R ｅ Each of these is independently an alkyl group, an alkenyl group, or an aryl group. X is a single bond, -CH ２ -----CHR ｆ -, -CR ｇ R ｈ -, -O-, -S-, -S (=O) ２ , -C(=O)O-, -C(=O)-NH-, or -C(=O)-, R ｆ ~R ｈ Each of these is independently an alkyl group, an alkenyl group, or an aryl group, or R ｇ and R ｈ These may also form a carbon ring together with the carbon atoms to which they are bonded. p represents an integer from 0 to 4. q represents an integer from 0 to 4. If n is 0, p is an integer greater than or equal to 1, and there is at least one R １ ga-CH ３ ien-CH ２ R ａ , or -CHR ｂ R ｃ And, If n is 1, then at least one of the following conditions (i) to (iii) is met. (i) X is -CH ２ - or - CHR ｆ - is (ii) p is an integer greater than or equal to 1 and at least one R １ ga-CH ３ ien-CH ２ R ａ or -CHR ｂ R ｃ That is (iii) q is an integer greater than or equal to 1 and at least one R ２ ga-CH ３ ien-CH ２ R ａ or -CHR ｂ R ｃ That is the case.

7. Furthermore, the resin composition according to claim 1 comprises one or more selected from phosphate ester compounds and phosphonic acid compounds.

8. The phosphonic acid compound is a phosphonic acid compound represented by the following formula (5A), The phosphate ester compound is a orthophosphate ester compound represented by the following formula (5B), or a condensed phosphate ester represented by the following formula (5C). The resin composition according to claim 7. 【Chemistry 2】 During the ceremony, R ２１ and R ２２ Each of these is independently a hydrogen atom, an alkyl group, or an aryl group, and the alkyl group and aryl group may have substituents. R ２３ is an alkyl group or an aryl group, and the alkyl group and aryl group may have substituents. 【Transformation 3】 During the ceremony, R ２４ ~R ２６ Each of these is independently a hydrogen atom, an alkyl group, or an aryl group, and the alkyl group and aryl group may have substituents, However, R ２４ ~R ２６ Not all of them are hydrogen atoms. 【Chemistry 4】 During the ceremony, R ２７ and R ２８ Each of these is independently an alkyl group or aryl group which may have substituents, Z is a divalent organic group containing at least one aromatic ring, and n is an integer greater than or equal to 1.

9. The resin composition according to claim 7, wherein the content of the phosphate ester compound and the phosphonic acid compound is 1 part by mass or more and 25 parts by mass or less in total per 100 parts by mass of the polyamide resin.

10. Furthermore, the resin composition according to claim 1, further comprising a filler.

11. The resin composition according to claim 10, wherein the filler is a fibrous alumina filler.

12. A film comprising the resin composition according to any one of claims 1 to 11.

13. A flexible display comprising the film described in claim 12.

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