Resin composition, film, and display device

Abstract

Provided is a resin composition capable of providing a film which has low yellowness while retaining good resilience. The resin composition comprises one or more resins (A) selected from among polyamide-imide resins and polyamide resins, a fibrous alumina filler (B), and a crosslinking agent (C) containing two or more functional groups of one or more kinds selected from among methylol groups and alkoxymethyl groups.

Description

Resin composition, film and display device

[0001] The present invention relates to a resin composition, a film, and a display device.

[0002] Foldable devices have recently attracted attention as they further enhance the portability of mobile information terminals such as smartphones and tablets. Glass has traditionally been used as a material for the cover window and other components used in the displays that make up such foldable devices. However, glass is a rigid material, and polymer films are used in terms of flexibility.

[0003] Polymer films are required to have not only flexibility but also excellent mechanical properties and excellent optical properties. To meet such requirements, for example, Patent Document 1 proposes a polymer film made of a resin composition containing a resin component and a fibrous alumina filler, wherein the resin component contains a resin having an imide structure and an amide structure, and the fibrous alumina filler is dispersed in the resin composition in a state where the average fiber diameter is 4 to 30 nm and the average fiber length is 200 to 4,000 nm.

[0004] International Publication No. 2021 / 221118

[0005] Polymer films are required to be less likely to develop pressure marks or flex marks (hereinafter referred to as "fold marks") on the film surface even when repeatedly folded or kept folded for a long period of time, as is expected in foldable devices. In this regard, Japanese Patent Laid-Open No. 2022-135876 discloses controlling the resilience of the film to improve the restoring force of the polyimide film against physical deformation due to external forces. Although the polymer film of Patent Document 1 has excellent mechanical properties, there is room for improvement in terms of resilience.

[0006] Furthermore, polymer materials used in displays are required to be colorless and transparent, particularly low in yellowness, and therefore polymer films with high resilience and low in yellowness are required to prevent the formation of folding marks.

[0007] The present inventors conducted extensive research to solve the above-mentioned problems and found that the resilience of a film obtained using a resin composition containing one or more resins selected from a polyamideimide resin and a polyamide resin can be improved by incorporating a thermally reactive crosslinking agent into the resin composition. However, when the resin composition further contains a fibrous alumina filler, the yellowness of the film obtained using the resin composition can be significantly increased depending on the type of thermally reactive crosslinking agent. The present inventors conducted further extensive research to reduce the yellowness and found that by incorporating a thermally reactive crosslinking agent containing two or more functional groups selected from methylol groups and alkoxymethyl groups as the thermally reactive crosslinking agent, the film obtained using the resin composition can have low yellowness while maintaining good resilience, thereby completing the present invention.

[0008] The present invention provides a resin composition comprising: (1) one or more resins (A) selected from polyamideimide resins and polyamide resins; (B) a fibrous alumina filler; and (C) a crosslinking agent containing two or more functional groups selected from methylol groups and alkoxymethyl groups. (2) The resin composition of (1), wherein the (A) component is a polyamideimide resin. (3) The resin composition of (1) or (2), wherein the (B) component is a boehmite or pseudo-boehmite alumina filler. (4) The resin composition of any one of (1) to (3), wherein the (C) component is a crosslinking agent having a melamine skeleton or a benzoguanamine skeleton. (5) The resin composition of any one of (1) to (4), wherein the (B) component is 1 to 50 parts by mass and the (C) component is 0.1 to 50 parts by mass per 100 parts by mass of the (A) component. [6] A film made using the resin composition of any one of [1] to [5]. [7] The film of [6], in which R according to the following formula (1) is 0.93 to 2.00 MPa: R=α·ε / 2 (1) In the formula, α is the yield strength (unit: MPa) and ε is the yield strain. [8] The film of [6] or [7], in which a yellow index is 0 or more and 3.0 or less. [9] A display device comprising the film of any one of [6] to [8].

[0009] The resin composition of the present invention provides a film that has low yellowness while maintaining good resilience. This film is expected to be less likely to develop creases even when repeatedly folded or kept folded for a long period of time.

[0010] FIG. 1 is an image diagram of a curve showing the relationship between stress applied to a film and the strain of the film in response to this stress.

[0011] <Resin Composition> The resin composition of the present invention contains one or more resins (A) selected from polyamideimide resins and polyamide resins, a fibrous alumina filler (B), and a crosslinking agent (C) containing two or more functional groups of one or more types selected from methylol groups and alkoxymethyl groups.

[0012] [Component (A)] The component (A) of the present invention may be one or more selected from polyamide resins and polyamideimide resins, and may be a polyamide resin alone, a polyamideimide resin alone, or a combination of a polyamide resin and a polyamideimide resin. The polyamide resin and the polyamideimide resin may be used alone or in combination of two or more. It is preferred that the resin component consists essentially of component (A).

[0013] (Polyamide-imide resin) The resin composition of the present invention can use a polyamide-imide resin. The polyamide-imide resin can be obtained by reacting a diamine compound, a tetracarboxylic acid compound, and a dicarboxylic acid compound, which are monomer components. Specifically, a polyamide-imide resin can be obtained by reacting a diamine compound with a tetracarboxylic acid compound to synthesize a polymer having an imide precursor structure, then reacting the polymer with a dicarboxylic acid compound to synthesize a copolymer having an imide precursor structure and an amide structure, and then subjecting the imide precursor structure in the copolymer to a ring-closing reaction (imidization). Alternatively, a diamine compound can be reacted with a tetracarboxylic acid compound to synthesize a polymer having an imide precursor structure, and the imide precursor can be subjected to a ring-closing reaction, followed by reaction with a dicarboxylic acid compound to synthesize a copolymer having an imide structure and an amide structure.

[0014] That is, the polyamide-imide resin can have a structure in which a residue resulting from the reaction of a diamine compound with a tetracarboxylic acid compound is bonded via an imide structure to a structural unit in which a residue resulting from the reaction of a diamine compound with a tetracarboxylic acid compound is bonded via an amide structure. In particular, the polyamide-imide resin preferably contains, as the residue resulting from the reaction of a diamine compound with a tetracarboxylic acid compound, at least one structure selected from the group consisting of fluorine atoms, aliphatic rings, and structures in which aromatic rings are linked together via a sulfonyl group or an alkylene group optionally substituted with a fluorine atom.

[0015] Examples of diamine compounds used in the synthesis of polyamide-imide resins include aliphatic diamines, aromatic diamines, and mixtures thereof. Here, "aromatic diamine" refers to a diamine in which an amino group is directly bonded to an aromatic ring, and may contain an aliphatic group or other substituent as part of its structure. This aromatic ring may be a single ring or a condensed ring, and examples include, but are not limited to, a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring. Among these, a benzene ring is preferred. Furthermore, "aliphatic diamine" refers to a diamine in which an amino group is directly bonded to an aliphatic group, and may contain an aromatic ring or other substituent as part of its structure. The diamine compounds can be used alone or in combination of two or more.

[0016] Specific examples of the aliphatic diamine include acyclic aliphatic diamines such as hexamethylenediamine, and cyclic aliphatic diamines such as 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, norbornanediamine, and 4,4'-diaminodicyclohexylmethane. These can be used alone or in combination of two or more.

[0017] Specific examples of aromatic diamines include aromatic diamines having one aromatic ring, such as p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, and 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, and bis(4-aminophenoxy)benzene. Examples of aromatic diamines include aromatic diamines having two or more aromatic rings, such as bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine (TFMB), 4,4'-bis(4-aminophenoxy)biphenyl, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-amino-3-methylphenyl)fluorene, 9,9-bis(4-amino-3-chlorophenyl)fluorene, and 9,9-bis(4-amino-3-fluorophenyl)fluorene. These may be used alone or in combination of two or more.

[0018] Among the above diamine compounds, from the viewpoint of improving the colorless transparency and elasticity of the film, it is preferable to use one or more selected from the group consisting of aromatic diamines having a biphenyl structure, specifically, one or more selected from the group consisting of 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-bis(4-aminophenoxy)biphenyl and 4,4'-diaminodiphenyl ether. Furthermore, from the viewpoint of easily improving the colorless transparency, it is more preferable to use a diamine having a biphenyl structure in which some or all of the hydrogen atoms on the aromatic ring are substituted with substituents selected from a fluoro group, a trifluoromethyl group, or a trifluoromethoxy group, specifically, 2,2'-bis(trifluoromethyl)benzidine.

[0019] The tetracarboxylic acid compound used in the synthesis of polyamide-imide resins includes tetracarboxylic acids or tetracarboxylic acid derivatives. Examples of tetracarboxylic acid derivatives include tetracarboxylic acid anhydrides, preferably dianhydrides and acid chlorides. Examples of tetracarboxylic acid compounds include aromatic tetracarboxylic acids and their anhydrides, preferably dianhydrides, and other aromatic tetracarboxylic acid compounds; aliphatic tetracarboxylic acid compounds and their anhydrides, preferably dianhydrides, and other aliphatic tetracarboxylic acid compounds. These tetracarboxylic acid compounds can be used alone or in combination of two or more.

[0020] Specific examples of the aromatic tetracarboxylic acid dianhydride include non-condensed polycyclic aromatic tetracarboxylic acid dianhydrides, monocyclic aromatic tetracarboxylic acid dianhydrides, and condensed polycyclic aromatic tetracarboxylic acid dianhydrides. Examples of non-condensed polycyclic aromatic tetracarboxylic dianhydrides include 4,4'-oxydiphthalic dianhydride (sODPA), 3,4-oxydiphthalic dianhydride (aODPA), 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic dianhydride (BPADA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,2',3,3'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride (sBPDA), 2,2',3,3'-biphenyl tetracarboxylic dianhydride (aBPDA), 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,2 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 dianhydride, 4,4'-(m-phenylenedioxy)diphthalic dianhydride, and 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF). Furthermore, examples of the monocyclic aromatic tetracarboxylic dianhydrides include 1,2,4,5-benzenetetracarboxylic dianhydride, and examples of the condensed polycyclic aromatic tetracarboxylic dianhydride include 2,3,6,7-naphthalenetetracarboxylic dianhydride.

[0021] Examples of the aliphatic tetracarboxylic acid dianhydride include cyclic and acyclic aliphatic tetracarboxylic acid dianhydrides. The cyclic aliphatic tetracarboxylic acid dianhydride is a tetracarboxylic acid dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include cycloalkane tetracarboxylic acid dianhydrides such as 1,2,4,5-cyclohexane tetracarboxylic acid dianhydride (HPMDA), 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride (CBDA), and 1,2,3,4-cyclopentane tetracarboxylic acid dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic acid dianhydride (HBPDA), and positional isomers thereof. These can be used alone or in combination of two or more. Specific examples of the acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride and 1,2,3,4-pentanetetracarboxylic dianhydride, which can be used alone or in combination of two or more. Also, a cyclic aliphatic tetracarboxylic dianhydride and an acyclic aliphatic tetracarboxylic dianhydride can be used in combination.

[0022] Among tetracarboxylic acid compounds, from the viewpoint of improving the bending resistance and optical properties of the film, aromatic tetracarboxylic acid dianhydrides having a substituent selected from a fluoro group, a trifluoromethyl group, or a trifluoromethoxy group, specifically 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA), and tetracarboxylic acid dianhydrides having a biphenyl structure, a fluorene structure, or an alicyclic hydrocarbon structure, specifically 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (sBPDA), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF) are preferred. It is preferable to use a combination of 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride and one selected from the group consisting of 1,2,3,4-cyclobutanetetracarboxylic dianhydride and dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride (6FDA:any one of sBPDA, BPAF, CBDA, and HBPDA), and it is more preferable that the molar ratio of 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride to one selected from the group consisting of 1,2,3,4-cyclobutanetetracarboxylic dianhydride and dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride (6FDA:sBPDA, BPAF, CBDA, and HBPDA) is 1:2.

[0023] Among tetracarboxylic acid compounds, from the viewpoint of improving transparency and adhesion without impairing various properties such as heat resistance and mechanical strength of the film, it is preferable to use a combination of 3,4-oxydiphthalic dianhydride (aODPA) and at least one selected from the group consisting of 4,4'-oxydiphthalic dianhydride (sODPA), 2,2',3,3'-biphenyltetracarboxylic dianhydride (aBPDA), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), and 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA).

[0024] The dicarboxylic acid compound used in the synthesis of polyamide-imide resins includes dicarboxylic acids and dicarboxylic acid derivatives, such as acid chlorides and esters of the dicarboxylic acids. The dicarboxylic acid compounds can be used alone or in combination of two or more.

[0025] Specific examples of the dicarboxylic acid compound include 1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic 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 compounds in which two cyclohexanecarboxylic acids or two benzoic acids are bonded to a single bond, -CH ２ -, -C(CH ３ ) ２ -, -C(CF ３ ) ２ -, -SO ２ alicyclic dicarboxylic acids or aromatic dicarboxylic acids such as compounds linked by a phenylene group or a phenylene group, and derivatives thereof (e.g., acid chlorides, acid anhydrides); aliphatic dicarboxylic acids such as dicarboxylic acid compounds of chain hydrocarbons having 8 or less carbon atoms, and derivatives thereof (e.g., acid chlorides, esters). These dicarboxylic acid compounds can be used alone or in combination of two or more.

[0026] Among these, from the viewpoint of improving the elongation at break and the elastic modulus of the film, it is preferable to use terephthalic acid or 4,4'-oxybisbenzoic acid or a derivative thereof, in particular terephthalic acid chloride (sometimes referred to as TPC) or 4,4'-oxybis(benzoyl chloride) (4,4'-diphenyl ether dicarboxylic acid chloride, sometimes referred to as DEDC).

[0027] In the synthesis of the polyamideimide resin of the resin composition of the present invention, the dicarboxylic acid compound may be more than 0 mol% and less than 100 mol% relative to the total of 100 mol% of the tetracarboxylic acid compound and the dicarboxylic acid compound. From the viewpoint of obtaining the effect of improving the resilience of the film by blending the amide structure and the thermally reactive crosslinking agent, the dicarboxylic acid compound is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 40 mol% or more. The constituent ratio of this monomer component is such that, among the repeating units in the polyamideimide resin, the amide structure is more than 0 mol%, preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 40 mol% or more. From the viewpoint of fully obtaining the effect of introducing the imide structure, the amide structure is preferably 90 mol% or less, more preferably 80 mol% or less.

[0028] For example, the molar ratio of the monomer components (diamine compound:tetracarboxylic acid compound:dicarboxylic acid compound) is preferably 7:0.5-4:3-6.5, more preferably 7:1.5-3.5:3.5-5.5, and particularly preferably 7:2.5-3.5:3.5-4.5. According to the above-described ratios of the monomer components, the molar ratio of imide structures to amide structures in the polyamide-imide resin structure is preferably 0.5-4:3-6.5, more preferably 1.5-3.5:3.5-5.5, and particularly preferably 2.5-3.5:3.5-4.5. By achieving the above-described ratio of imide structures to amide structures, a good balance between excellent flexibility and high elasticity can be achieved.

[0029] The ring-closing reaction (imidization) of the imide precursor in the synthesis of the polyamide-imide resin can be carried out by either thermal imidization, in which an azeotropic solvent (e.g., toluene, xylene, etc.) that forms an azeotrope with water is added and heated, or chemical imidization, in which a condensing agent and a reaction accelerator are used. Chemical imidization is preferred because it is easier to maintain colorless transparency.

[0030] Examples of reaction accelerators used in chemical imidization 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 can be used alone or in combination of two or more.

[0031] Condensing agents used in chemical imidization include acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride, and phosphites such as triethyl phosphite, triethyl phosphite, tributyl phosphite, dimethyl phosphite, diethyl phosphite, and triphenyl phosphite. These condensing agents can be used alone or in combination of two or more.

[0032] The organic solvent used in the synthesis of polyamide-imide resin is not particularly limited as long as it is an organic solvent inert to the reaction. Examples include N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, m-cresol, γ-butyrolactone, cyclopentanone, cyclohexanone, tetrahydrofuran, etc. These organic solvents can be used alone or in combination of two or more.

[0033] The ring-closing reaction conditions for synthesizing the polyamide-imide resin can be 10 to 50° C. for 1 to 27 hours, and it is preferable to synthesize the resin in a nitrogen atmosphere in order to maintain colorless transparency.

[0034] From the viewpoint of improving the elastic modulus and elongation at break, the weight average molecular weight (Mw) of the polyamide-imide resin is preferably in the range of 50,000 to 1,000,000, more preferably in the range of 80,000 to 800,000, and even more preferably in the range of 110,000 to 600,000. Note that, in this specification, the weight average molecular weight (Mw) is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene, and specifically, is measured by the method described in the Examples.

[0035] (Polyamide Resin) The resin composition of the present invention can use a polyamide resin. The polyamide resin can be obtained by reacting a diamine compound and a dicarboxylic acid compound, which are monomer components. The dicarboxylic acid compound is a dicarboxylic acid or a derivative thereof (e.g., an acid chloride, an ester, etc.).

[0036] That is, the polyamide resin may have an amide structure formed by the reaction of a diamine compound and a dicarboxylic acid compound. The repeating units constituting the polyamide resin differ from the polyamideimide resin in that they do not substantially contain an imide structure. Furthermore, it is more preferable that the structure connecting the monomer components constituting the polyamide resin is substantially free of repeating structures other than the amide structure and is composed of an amide structure.

[0037] Here, the description of the diamine compound (including examples and preferred examples) described in the section on polyimideamide resins above applies to the diamine compound, and the description of the dicarboxylic acid compound (including examples and preferred examples) described in the section on polyimideamide resins above applies to the dicarboxylic acid compound.

[0038] Among the above diamine compounds, from the viewpoint of improving the colorless transparency and elasticity of the film, it is preferable to use one or more selected from the group consisting of aromatic diamines having a biphenyl structure, specifically, one or more selected from the group consisting of 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-bis(4-aminophenoxy)biphenyl and 4,4'-diaminodiphenyl ether. Furthermore, from the viewpoint of easily improving the colorless transparency, it is more preferable to use a diamine having a biphenyl structure in which some or all of the hydrogen atoms on the aromatic ring are substituted with substituents selected from a fluoro group, a trifluoromethyl group, or a trifluoromethoxy group, specifically, 2,2'-bis(trifluoromethyl)benzidine.

[0039] Among the above dicarboxylic acid compounds, from the viewpoint of improving the elongation at break and modulus of elasticity of the film, it is preferable to use terephthalic acid or 4,4'-oxybisbenzoic acid or a derivative thereof, in particular terephthalic acid chloride (sometimes referred to as TPC) or 4,4'-oxybis(benzoyl chloride) (4,4'-diphenyl ether dicarboxylic acid chloride, sometimes referred to as DEDC). It is also preferable to use TPC and DEDC in combination, in which case the molar ratio (moles of TPC:moles of DEDC) can be 1:4 to 4:1, preferably 2:3 to 4:1. At these molar ratios, structural units derived from TPC and structural units derived from DEDC are essentially introduced into the polyamide resin.

[0040] The polyamide resin can be produced by a known method for producing polyamides, such as a solution polymerization method, an interfacial polymerization method, a melt polymerization method, a solid-state polymerization method, etc. In particular, the solution polymerization method and the interfacial polymerization method are preferably used as methods for producing aromatic polyamides.

[0041] Specifically, polyamide resins can be synthesized from dicarboxylic acid chlorides and diamine compounds by solution polymerization, in which the reaction can be carried out in an aprotic organic polar solvent.

[0042] In this reaction, hydrogen chloride is produced as a by-product, and to neutralize this, an inorganic neutralizing agent such as calcium hydroxide, calcium carbonate, or lithium carbonate, or an organic neutralizing agent such as 1,2-butylene oxide, ethylene oxide, propylene oxide, ammonia, or pyridine, is used.

[0043] When two or more diamine compounds are used for polymerization, various methods can be used, such as adding one diamine compound at a time, adding 10 to 99 mol% of a dicarboxylic acid dichloride to the diamine compound, and then reacting the diamine compound with another diamine compound, followed by adding a dicarboxylic acid dichloride, followed by reacting the other diamine compound and the dicarboxylic acid dichloride. Alternatively, all diamine compounds can be mixed and added, followed by adding a dicarboxylic acid dichloride, followed by reacting the other diamine compounds. Similarly, when two or more dicarboxylic acid dichlorides are used, various methods, such as a stepwise method or simultaneous addition, can be used. The molar ratio of all diamine compounds to all dicarboxylic acid dichlorides (moles of all diamine compounds:moles of all dicarboxylic acid dichlorides) can be adjusted appropriately depending on the molecular weight of the desired polyamide. For example, a ratio of 49:51 to 51:49 can be used to obtain a polyamide with a sufficiently high molecular weight and excellent mechanical properties.

[0044] When a diamine compound and a dicarboxylic acid dichloride are used as raw materials, the end terminals are either amine or carboxylic acid depending on the composition ratio of the raw materials. From the viewpoint of improving the colorless transparency of the film, it is preferable to perform end-capping with other amines, carboxylic acid chlorides, or carboxylic acid anhydrides.

[0045] Examples of compounds used for terminal blocking include acetyl chloride, benzoyl chloride, substituted benzoyl chloride, acetic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, 4-ethynylaniline, 4-phenylethynylphthalic anhydride, maleic anhydride, etc. Terminal blocking may not be performed, in which case the terminal group can be used as a crosslinking point, etc.

[0046] Examples of aprotic polar solvents used in the production of polyamide resins 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, and hexamethylphosphoramide and γ-butyrolactone. These are preferably used alone or as a mixture, but aromatic hydrocarbons such as xylene and toluene can also be used. Furthermore, up to 50% by mass of an alkali metal or alkaline earth metal salt can be added to the solvent to promote dissolution of the polymer.

[0047] The reaction conditions for synthesizing the polyamide resin can be 10 to 50° C. and 10 minutes to 27 hours, and it is preferable to synthesize the polyamide resin under a nitrogen atmosphere in order to maintain colorless transparency.

[0048] From the viewpoint of improving mechanical properties, the polyamide resin of the present invention preferably has a number average molecular weight (Mn) of 5,000 or more and 200,000 or less, and more preferably 10,000 or more and 180,000 or less.

[0049] From the viewpoint of improving mechanical properties, the polyamide resin of the present invention preferably has a weight average molecular weight (Mw) of 10,000 or more and 1,000,000 or less, more preferably 50,000 or more and 500,000 or less, and even more preferably 100,000 or more and 300,000 or less.

[0050] The polyamide resin of the present invention preferably has a polydispersity (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.

[0051] The resin in the resin composition of the present invention preferably has substantially no hydroxyl groups or carboxyl groups. When the resin has hydroxyl groups or carboxyl groups, the crosslinking density increases significantly due to crosslinking between the resin and the thermally reactive crosslinking agent described below, which may significantly reduce the flexibility of the resin. By having the resin substantially free of hydroxyl groups and carboxyl groups, the resilience of the resin can be increased while maintaining its flexibility.

[0052] [Component (B)] The component (B) of the present invention is a fibrous alumina filler, and includes fibrous fillers made of alumina and alumina hydrate. The term "fibrous" refers to a shape having an aspect ratio (filler length / filler diameter) of 5 or more. Examples of alumina hydrate include boehmite and pseudo-boehmite. Component (B) is preferably a boehmite or pseudo-boehmite alumina filler. Component (B) can be used alone or in combination of two or more.

[0053] The fibrous alumina filler (component (B)) is preferably dispersed in the resin composition of the present invention containing the above-mentioned resin component (component (A)) in a state where the average fiber diameter is 1 to 30 nm and the average fiber length is 100 to 4,000 nm. When the fibrous alumina filler is dispersed in this state, the fibers are arranged in a lattice pattern in the resin composition, which is thought to be able to impart a significant effect of high elasticity while suppressing coloration, turbidity, and a decrease in flexibility. Furthermore, compared to spherical or amorphous fillers, the fibrous alumina filler can impart an excellent anti-blocking effect without impairing light transmittance. Specifically, when films made of the resin composition of the present invention are stacked on top of each other or rolled up for storage, the fibrous alumina filler can suppress sticking (blocking) between the films, thereby improving storage stability and workability.

[0054] The fibrous alumina filler (component (B)) in the resin composition of the present invention is preferably dispersed in a state in which the average fiber diameter is 1 to 30 nm and the average fiber length is 100 to 4,000 nm, more preferably in a state in which the average fiber diameter is 2 to 25 nm and the average fiber length is 200 to 3,000 nm, and even more preferably in a state in which the average fiber diameter is 3 to 20 nm and the average fiber length is 500 to 2,000 nm. Dispersing the fibrous alumina filler in the resin composition in a state in which the average fiber diameter and average fiber length are within the above-mentioned ranges is advantageous in that a film made using this resin composition is suppressed in coloration and turbidity and achieves high elasticity while maintaining flexibility. The "average fiber diameter" and "average fiber length" of the fibrous alumina filler in the dispersed state in the resin composition of the present invention are measured by diluting the resin composition 10,000 times with the solvent used to prepare the resin composition (e.g., methyl isobutyl ketone (MIBK) or dimethylacetamide (DMAc)), dropping one drop onto a cover glass (Cover Glass Trophy, manufactured by Matsunami Glass Co., Ltd.), drying at 50°C, and then observing the image under an electron microscope (e.g., a 10,000x magnification image using an FE-SEM manufactured by Hitachi High-Tech). The fibrous alumina filler to be measured may be in the form of either a single fiber or a fiber bundle in which multiple single fibers are aggregated, as long as it is visible as a single fiber in the electron microscope image. The average measured length of the diameter in the short side direction of 50 arbitrarily selected fibrous alumina fillers in the electron microscope image is taken as the "average fiber diameter," and the average measured length in the long side direction is taken as the "average fiber length."

[0055] The fibrous alumina filler (component (B)) is blended in the form of a powder or a dispersion (sol) described below with component (A) and component (C), and optionally with any other component, and stirred and kneaded as necessary, thereby adjusting the dispersion state in the resin composition, i.e., the "average fiber diameter" and "average fiber length." For example, stirring or kneading can be performed using a stirrer such as a dissolver or butterfly mixer, or a kneader such as a roll mill or bead mill. The average fiber diameter and length can be adjusted by adjusting 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.

[0056] The fibrous alumina filler (component (B)) can be surface-treated or used as a dispersion (sol) in which it is dispersed in an organic solvent or the like. By surface-treating it or incorporating it as a dispersion, the dispersed state in the resin composition can be stabilized. In particular, by using a dispersion (sol) in which the dispersed state of the fibrous alumina filler is adjusted to be the same as the dispersed state of the fibrous alumina filler in the resin composition of the present invention, i.e., the "average fiber diameter" and "average fiber length", the resin composition of the present invention can be produced with good productivity.

[0057] The method for surface treatment of the fibrous alumina filler (component (B)) or for preparing a dispersion is not particularly limited, and for example, a surface treatment method using a coupling agent such as a silane-based, titanate-based, aluminate-based, or zircoaluminate-based coupling agent, or the method for producing an organic sulfonic acid-treated dispersion disclosed in JP-A-2008-31010 can be used.

[0058] Examples of the fibrous alumina filler (component (B)) include the Aluminosol series manufactured by Kawaken Fine Chemicals.

[0059] [Component (C)] The component (C) of the present invention is a crosslinking agent containing two or more functional groups selected from methylol groups and alkoxymethyl groups. Component (C) can be used alone or in combination of two or more. In the present invention, the alkoxymethyl group is -CH ２ It is a group represented by —O—R, where R is an alkyl group. R is preferably an alkyl group having 1 to 6 carbon atoms, more preferably 1 or 2 carbon atoms, and particularly preferably 1 carbon atom.

[0060] The one or more functional groups selected from a methylol group and an alkoxymethyl group are preferably a methylol group or a methoxymethyl group.

[0061] Component (C) can be a crosslinking agent having a melamine skeleton, a crosslinking agent having a guanamine skeleton, a crosslinking agent having a glycoluril skeleton, or the like. Compounds of these types containing two or more methylol groups or alkoxymethyl groups are preferred. Compounds of these types known as thermally reactive crosslinking agents can also be used.

[0062] The crosslinking agent having a melamine skeleton is a compound having a melamine structure and containing two or more functional groups of one or more types selected from methylol groups and alkoxymethyl groups, and a compound represented by formula (1) can be used as component (C). Oligomers of these compounds can also be used. In the formula, R １ is a hydrogen atom or an alkyl group (preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group or an ethyl group, and particularly preferably a methyl group).

[0063] The crosslinking agent having a benzoguanamine skeleton is a compound having a benzoguanamine structure and containing two or more functional groups selected from one or more types of functional groups selected from methylol groups and alkoxymethyl groups, and a compound represented by formula (2) can be used as component (C). Oligomers of these compounds can also be used. In the formula, R ２ is a hydrogen atom or an alkyl group (preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group or an ethyl group).

[0064] The crosslinking agent having a glycoluril skeleton is a compound having a glycoluril structure containing two or more functional groups of one or more types selected from methylol groups and alkoxymethyl groups, and examples of component (C) include 1,3,4,6-tetrakis(hydroxymethyl)glycoluril, 1,3,4,6-tetrakis(methoxymethyl)glycoluril, and 1,3,4,6-tetrakis(butoxymethyl)glycoluril.

[0065] As the component (C), hexamethylolmelamine, hexamethoxymethylmelamine, tetramethylolbenzoguanamine, tetramethoxymethylbenzoguanamine, and oligomers thereof are preferred.

[0066] [Resin Composition] In the resin composition of the present invention, the amount of component (B) is preferably 1 to 50 parts by mass, more preferably 5 to 40 parts by mass, and the amount of component (C) is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 40 parts by mass, and even more preferably 1 to 30 parts by mass, relative to 100 parts by mass of component (A). Within these ranges, the resin composition of the present invention can be used to produce a film that has low yellowness while maintaining good resilience.

[0067] The resin composition of the present invention may contain any additives in addition to the components (A) to (C), provided that the effects of the present invention are not impaired. Specific examples of such additives include fillers other than the fibrous alumina filler (B), leveling agents, dispersants, surfactants, retardation adjusters, antioxidants, ultraviolet inhibitors, light stabilizers, plasticizers, waxes, bulking agents, pigments, dyes, foaming agents, antifoaming agents, dehydrating agents, antistatic agents, antibacterial agents, antifungal agents, bluing agents for reducing the yellowness of the film, phosphorus compounds, lubricants, and pH adjusters.

[0068] The resin composition of the present invention can be prepared as a resin composition (resin varnish) by dissolving one or more resins selected from polyamide resins and polyamideimide resins and a thermally reactive crosslinking agent in a solvent. The solvent is not particularly limited as long as it can dissolve the above components, but from the viewpoints of the coatability of the resin varnish and the transparency of the resulting film, a solvent containing one or more groups selected from the group consisting of an ester group, an ether group, a ketone group, a hydroxyl group, a sulfone group, and a sulfinyl group is preferred.

[0069] Examples of solvents having an ester group include ester solvents such as methyl acetate, ethyl acetate, butyl acetate, dimethyl carbonate, etc. Solvents having a cyclic ester group can also be used, including lactone solvents such as γ-butyrolactone (GBL), δ-valerolactone, ε-caprolactone, γ-crotonolactone, γ-hexanolactone, α-methyl-γ-butyrolactone, γ-valerolactone, α-acetyl-γ-butyrolactone, δ-hexanolactone, etc.

[0070] Examples of solvents having an ether group include tetrahydrofuran, dioxane, and dibutyl ether. Examples of solvents having a ketone group include ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of solvents having a hydroxyl group include phenol-based solvents such as m-cresol. Examples of solvents having a sulfone group include methyl sulfone, ethyl phenyl sulfone, diethyl sulfone, diphenyl sulfone, sulfolane, bisphenol S, sorapsone, dapsone, bisphenol A polysulfone, and sulfolane. Examples of solvents having a sulfinyl group include sulfoxide-based solvents such as N,N-dimethyl sulfoxide (DMSO). In addition to the solvents listed above, amide-based solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), and N,N-dimethylacetamide (DMAc) can also be used.

[0071] The resin composition of the present invention has a wide range of applications, for example, as a material for films, sheets, pipes, tubes, filaments, fibers, containers, etc. Among these, it is particularly suitable for use as a material for films.

[0072] [Film] The film of the present invention is a film made using the resin composition of the present invention. For example, the film can be obtained by forming the resin composition of the present invention into a resin varnish, applying it to a support, drying it, and then peeling it off from the support. It is presumed that the heat generated during film production forms a crosslinked structure due to the thermally reactive crosslinking agent, thereby improving the resilience of the film.

[0073] Here, resilience means the energy per unit volume that a material can absorb without permanent deformation. The resilience of a film corresponds to the area of ​​the hatched elastic deformation region in the image of Figure 1, which is related to the curve showing the relationship between the stress applied to the film and the strain of the film in response to this stress in a tensile test of the film. High resilience means high elastic recovery force, and a film with high resilience is expected to easily recover to its original state even when repeatedly folded or kept in a folded state for a long time, and to be less likely to leave creases.

[0074] As described above, resilience is determined as the area in the elastic deformation region, but by approximating the stress-strain curve of the elastic deformation region to a triangle as shown in Figure 1, an approximate value can be evaluated using R in the following formula (1). R of the film of the present invention is preferably 0.93 MPa or more, and may be 2.00 MPa or less. R = α · ε / 2 (1) In the formula, α is the yield strength (unit: MPa) and ε is the yield strain. The yield strength is the stress at the yield point in the stress-strain curve, and the yield strain is the strain at the yield point.

[0075] The yield strength and yield strain of the film can be measured by the methods described in the Examples.

[0076] The film of the present invention preferably has a yield strength of 70 to 200 MPa, more preferably 100 to 180 MPa.

[0077] The film of the present invention preferably has a yield strain of 0.1 to 20%, more preferably 0.5 to 10%.

[0078] The film of the present invention has a low yellowness, and the YI value (yellow index) is preferably from 0 to 3.0, more preferably from 0 to 2.5, and even more preferably from 0 to 2.0. The closer the YI value is to 0, the more excellent the colorlessness is.

[0079] The YI value can be measured by the method described in the Examples, but the YI value referred to here means an actual measured value that has not been normalized by the film thickness.

[0080] The film of the present invention preferably has a thickness of 5 to 100 μm, more preferably 10 to 70 μm. Within this range, excellent flexibility can be easily obtained, and the film can be suitably used as a cover window for a foldable display or a flexible display.

[0081] The film of the present invention can be obtained by drying a coating film of the resin composition of the present invention. For example, the film of the present invention can be obtained by forming the resin composition of the present invention into a resin varnish, applying it to a support, drying it, and then peeling it off from the support.

[0082] The coating method is not particularly limited, and known methods can be used, such as dip coating, flow coating, roll coating, bar coating, blade coating, screen printing, curtain coating, spray coating, etc. The coating thickness can be adjusted depending on the thickness of the film.

[0083] There are no particular limitations on the drying conditions as long as the temperature is such that the solvent volatilizes, but from the viewpoint of obtaining a film with excellent transparency, drying at 60 to 250° C. for about 10 to 60 minutes is preferred.

[0084] [Display Device] The film of the present invention can be used as a component of a display device, and the present invention relates to a display device including the film of the present invention.

[0085] The film of the present invention can be suitably used as a cover window for a display device, and can be used, for example, by placing the film on the surface of various display devices. The method for placing the film on the surface is not particularly limited, and examples thereof include a method using an adhesive layer. Known adhesive materials can be used as the material for the adhesive layer. A cover window using the film of the present invention may be provided with a protective layer such as a hard coat layer on the film surface, and may further include a fingerprint prevention layer.

[0086] The display device of the present invention may be a flexible type or a non-flexible type. Flexible types include foldable types that can be folded, rollable types that can be rolled into a cylindrical shape, etc. The film of the present invention has high resilience and is therefore suitable for flexible type display devices, and is particularly suitable for foldable type display devices.

[0087] The type of display is not particularly limited, and examples include a liquid crystal display device (LCD), an organic EL display, an inorganic EL display, a field emission display (FED), and an electrophoretic display.

[0088] Devices equipped with the display device of the present invention are not particularly limited, and examples include mobile terminals such as mobile phones, smartphones and wristwatch-type terminals, personal computers, televisions, large screens, and digital signage (electronic billboards and bulletin boards).

[0089] The film of the present invention can also be applied to TFT substrates for organic EL displays, touch panel members, flexible printed circuit boards, solar cell panel members such as surface protection films and substrate materials, optical waveguide members, and other semiconductor-related members.

[0090] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. In the following, "parts" and "%" are all by mass unless otherwise specified.

[0091] <Measurement Methods> The physical properties of the polyamide resins and polyamide films produced in the examples were measured as follows.

[0092] (1) Film Thickness The film thickness of the prepared film was measured using a micrometer (manufactured by Mitutoyo Corporation).

[0093] (2) YI Value (Yellow Index) The prepared films were cut into a size of 30 mm x 30 mm, and the YI value (actual measured value) of each film was determined in accordance with ASTM D1925 using a spectrophotometer (Konica Minolta, product number: CM-5). Each measured YI value was normalized by the film thickness (50 μm thickness) using the following formula to determine the YI value (50 μm equivalent): YI value (50 μm equivalent) = YI value (actual measured value) × 50 μm / film thickness

[0094] (3) Yield Strength and Yield Strain The prepared film was cut to a predetermined size, and the yield strength and yield strain (ε) were measured using a small tabletop testing machine (Shimadzu Corporation, product number: EZ-SX). The strain was calculated using the following formula (2), and the modulus of elasticity was calculated from the slope of the obtained stress-strain curve where the stress was from 5 MPa to 10 MPa. The strain and stress at the 0.2% proof stress point in the stress-strain curve were taken as the yield strain and yield strength, respectively. Measurements were carried out with n=3, and the average values ​​of the measurement results are shown in Table 1. Strain = (L １ -L ０ ) / L ０ (2) L ０ is the initial length of the film used in the measurement, L １ is the length of the film for a certain stress. [Test conditions] Sample size: 100 mm x 10 mm Distance between grippers: 50 mm Speed: 5 mm / min Number of measurements: 3

[0095] (4) Evaluation of Resilience The resilience was evaluated by R in the following formula (1): R=α·ε / 2 (1) where α and ε are the yield strength (unit: MPa) and yield strain measured above.

[0096] (5) Weight-average molecular weight (Mw) The weight-average molecular weight (Mw) is a polystyrene equivalent value measured by gel permeation chromatography (GPC). The conditions for the GPC measurement are as follows: Apparatus: GL7700 manufactured by GL Sciences; Column: TSKgel αM (manufactured by Tosoh Corporation); Column temperature: 40°C; Eluent composition: 100 mmol / L H ３ P.O. ４ (H ３ P.O. ４NMP solution containing 85% aqueous solution as raw material) and 10 mmol / L LiBr Eluent flow rate: 0.7 mL / min Calibration standard reagent: polystyrene Detector wavelength: 260 nm and 300 nm Detector temperature: room temperature Baseline range during analysis: 15 to 40 minutes Molecular weight calculation range during analysis: 20 to 35 minutes

[0097] <Production of Polyamideimide> A 100 mL reactor was charged with 60.0 g of N,N-dimethylacetamide (DMAc), and 4.849 g (15.14 mmol) of 2,2'-bis(trifluoromethyl)benzidine (TFMB) was added. Next, 1.007 g (3.245 mmol) of 3,4-oxydiphthalic dianhydride (aODPA) and 1.007 g (3.245 mmol) of 4,4'-oxydiphthalic dianhydride (sODPA) were added to the TFMB solution, and the mixture was stirred at 30°C for 2 hours to react, yielding a solution containing a polymer having an imide precursor structure. Thereafter, 1.757 g (8.653 mmol) of terephthaloyl chloride (TPC) was added to the solution, and the mixture was stirred and reacted for 1.5 hours while maintaining the liquid temperature at 30°C, yielding a solution containing a copolymer having an imide precursor structure and an amide structure. Subsequently, 2.09 g of pyridine, 2.45 g of acetic anhydride, and 8.53 g of DMAc were added and stirred at 20 to 30°C for 8 hours to obtain a polyamideimide solution. Further, 99 g of DMAc was added and stirred until homogenous, and the solution was gradually poured into a container containing 4 L of methanol to cause precipitation. The precipitated solids were filtered and pulverized, and then dried in a vacuum at 80°C for 18 hours to obtain 8.0 g of polyamideimide copolymer (PAI) as a solid powder. The weight average molecular weight in terms of polystyrene measured by GPC was 221,000.

[0098] <Film Production> In the blending amounts (solid content parts by mass) shown in Table 1, polyamideimide resin (PAI) powder and a thermally reactive crosslinking agent were dissolved in a solvent (DMAc) to adjust the solid content concentration to 13% by mass, and then a fibrous alumina filler dispersion was blended, dispersed, and homogenized to prepare a resin composition for film production. Next, this resin composition was applied to a glass plate using a table coater (AFA-standard manufactured by Cortec Co., Ltd.) with an applicator so that the final film thickness was approximately 50 μm. The film was then dried in a precision incubator (Fine Oven DH612 manufactured by Yamato Scientific Co., Ltd.) at 120 ° C. for 20 minutes, followed by 220 ° C. for 30 minutes, and then peeled off from the glass plate to form a film. The evaluation of each obtained film is shown in Table 1.

[0099]

[0100] The components used in Table 1 are as follows: Pseudoboehmite filler: Alumina filler manufactured by Kawaken Fine Chemicals (average fiber diameter: 5 nm, average fiber length: 800 nm, added as a slurry dispersed in DMAc at a concentration of 10%, values ​​in the table exclude solvent); Nikalac MW-390 manufactured by Sanwa Chemical Co., Ltd. ・Miki Riken Kogyo Co., Ltd. Rikenresin MM-630 hexamethylol melamine compound ・Sanwa Chemical Co., Ltd. TTMOBGN alkoxymethylol benzoguanamine compound ・Mitsubishi Chemical Corporation JER828 bisphenol A type epoxy resin epoxy equivalent 184-194g / eq ・Mitsubishi Chemical Corporation TAIC triallyl isocyanurate ・K.I. Kasei Co., Ltd. BMI-80

[0101] As shown in Table 1, the films of the Examples had low yellowness while maintaining good resilience. On the other hand, the films of Comparative Examples 2 to 4, which used a crosslinking agent other than component (C), were inferior in at least one of resilience and yellowness.

[0102] The resin composition for films of the present invention provides a film having low yellowness while maintaining good resilience. This film is expected to be less likely to develop folding marks even when repeatedly folded or kept folded for a long period of time, and is therefore highly useful in industry.

Claims

1. A resin composition comprising: one or more resins (A) selected from polyamideimide resins and polyamide resins; a fibrous alumina filler (B); and a crosslinking agent (C) containing two or more functional groups selected from methylol groups and alkoxymethyl groups.

2. The resin composition according to claim 1, wherein the component (A) is a polyamideimide resin.

3. The resin composition according to claim 1, wherein the component (B) is a boehmite or pseudo-boehmite alumina filler.

4. The resin composition according to claim 1, wherein the component (C) is a crosslinking agent having a melamine skeleton or a crosslinking agent having a benzoguanamine skeleton.

5. The resin composition according to claim 1, wherein the amount of the (B) component is 1 to 50 parts by mass and the amount of the (C) component is 0.1 to 50 parts by mass per 100 parts by mass of the (A) component.

6. A film made using the resin composition according to any one of claims 1 to 5.

7. The film according to claim 6, wherein R according to the following formula (1) is 0.93 to 2.00 MPa: R=α·ε / 2 (1) where α is the yield strength (unit: MPa) and ε is the yield strain.

8. The film according to claim 6, having a yellow index of 0 or more and 3.0 or less.

9. A display device comprising the film according to claim 6.

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