Resin composition, molded article, resin film, and method for producing resin film

Abstract

To provide a resin composition which has transparency and appearance suitable as an optical film, has small chromatic aberration (little color bleeding), has a high drying rate of a solvent when formed into a film by a solution casting method, and has excellent heat resistance, and to provide a molded article, a resin film, and a method for producing a resin film.SOLUTION: A resin composition comprising an acrylic resin and a polyimide resin, wherein the polyimide resin has a structure derived from a diamine and a structure derived from a tetracarboxylic dianhydride, and the structure derived from the diamine has a structure selected from CF3-O -, - (CF2-O) n -, and - O - (CF2-CF2-O) n -, wherein n is an integer of 1 to 20; In the resin composition, the polyimide resin is contained in a range of 0.1% by weight or more and 25% by weight or less with respect to the total of the acrylic resin and the polyimide resin, and the acrylic resin and the polyimide resin are compatible with each other in a solvent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a molded article, a resin film, and a method for producing a resin film. [Background technology]

[0002] Acrylic resins, typified by polymethyl methacrylate (hereinafter sometimes abbreviated as "PMMA"), are suitably used in optical films due to their excellent transparency, dimensional stability, low moisture absorption, and the like.

[0003] However, acrylic films have poor heat resistance and have the problem of changing shape when used at high temperatures or for long periods of time.

[0004] In order to improve heat resistance, a method of adding polycarbonate to acrylic resin has been proposed, as in Patent Document 1, for example. However, since the compatibility between the resins is insufficient, the resulting resin tends to become cloudy, making it difficult to use as an optical film.

[0005] On the other hand, acrylic films are sometimes produced by a solution casting method in which an acrylic resin dissolved in an organic solvent is cast into a film. For example, Patent Document 2 describes a production method in which, when an acrylic resin is formed into a film by a solution casting method, the solvent is dried until the acrylic film becomes self-supporting on the substrate, and then the acrylic film is peeled off from the substrate.

[0006] However, when an acrylic resin is used to form a film by the solution casting method as described above, it takes a long time to dry the solvent, resulting in poor productivity and sometimes causing defects such as uneven thickness and uneven appearance in the finished acrylic film. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 3119457 [Patent Document 2] Patent Publication No. 2007-176982 Summary of the Invention [Problem to be solved by the invention]

[0008] In view of the above problems, the present invention aims to provide a resin composition, a molded article, a resin film, and a method for producing a resin film that have transparency and appearance suitable for an optical film, a fast solvent drying rate when formed into a film by a solution casting method, and excellent heat resistance, as well as a resin composition and a resin film that have small chromatic aberration (little color bleeding). [Means for solving the problem]

[0009] As a result of extensive research, the present inventors have found that the above problems can be solved by the following configuration.

[0010] 1) A resin composition containing an acrylic resin and a polyimide resin, wherein the polyimide resin has a structure derived from a diamine and a structure derived from a tetracarboxylic dianhydride, and the structure derived from the diamine is CF3-O-, -(CF2-O) n -, -O-(CF2-CF2-O) n - (where n is an integer of 1 to 20), wherein the polyimide resin is contained in the resin composition in an amount of 0.1% by weight or more and 25% by weight or less based on the total weight of the acrylic resin and the polyimide resin, and the acrylic resin and the polyimide resin are compatible with each other in a solvent.

[0011] 2) The resin composition according to 1), wherein the acrylic resin is an acrylic resin containing methyl methacrylate as a main component.

[0012] 3) A resin composition according to 1) or 2), characterized in that the polyimide resin has a ratio of diamine-derived structures having a CF3- group directly bonded to an aromatic ring or a -C(CF3)2- group directly bonded to an aromatic ring, relative to the total amount of structures derived from the diamine, of less than 0.5 mol %, and a ratio of tetracarboxylic dianhydride-derived structures having a CF3- group directly bonded to an aromatic ring or a -C(CF3)2- group directly bonded to an aromatic ring, relative to the total amount of structures derived from the tetracarboxylic dianhydride, of less than 0.5 mol %.

[0013] 4) The CF3-O-, -(CF2-O) n -, -O-(CF2-CF2-O) n The resin composition according to any one of 1) to 3), characterized in that the diamine having a structure selected from - (wherein n is an integer of 1 to 20) is selected from 2,2'-bis(trifluoromethoxy)benzidine, 3,3'-bis(trifluoromethoxy)benzidine, and 2,3'-bis(trifluoromethoxy)benzidine.

[0014] 5) The resin composition according to any one of 1) to 4), wherein the polyimide resin contains a structure derived from an alicyclic tetracarboxylic dianhydride as a structure derived from a tetracarboxylic dianhydride, and the structure derived from the alicyclic tetracarboxylic dianhydride accounts for 1 to 80 mol% of the total amount of structures derived from the tetracarboxylic dianhydride.

[0015] 6) The resin composition according to any one of 1) to 5), wherein the polyimide resin contains a structure derived from a tetracarboxylic dianhydride having a fluorene structure as the structure derived from a tetracarboxylic dianhydride.

[0016] 7) A molded article comprising the resin composition according to any one of 1) to 6).

[0017] 8) A resin film comprising the resin composition according to any one of 1) to 6).

[0018] 9) The resin film according to 8), having a total light transmittance of 90% or more, a haze of 1% or less, and a yellowness index of 1.0 or less.

[0019] 10) A method for producing a resin film, comprising: a dissolving step of dissolving the resin composition according to any one of 1) to 6) in a solvent to prepare a resin solution; a coating step of applying the resin solution onto a support to form a coating film; a drying step of drying the coating film so that the residual solvent is 5 to 20% by weight; and a peeling step of peeling the dried coating film from the support to obtain a green sheet. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a resin composition, a molded article, a resin film, and a method for producing a resin film, which have transparency and appearance suitable for an optical film, small chromatic aberration (little color bleeding), a fast solvent drying rate when formed into a film by a solution casting method, and excellent heat resistance. Furthermore, by using a fluorine compound that is highly environmentally degradable, a transparent film with low environmental residue can be obtained. DETAILED DESCRIPTION OF THE INVENTION

[0021] [Resin composition] One embodiment of the present invention is a resin composition containing an acrylic resin and a polyimide resin, wherein the polyimide resin has a structure derived from a diamine and a structure derived from a tetracarboxylic dianhydride, and the structure derived from the diamine is selected from the group consisting of CF3-O-, -(CF2-O) n -, -O-(CF2-CF2-O) n - (where n is an integer of 1 to 20), the polyimide resin is contained in the resin composition in an amount of 0.1% by weight or more and 25% by weight or less based on the total weight of the acrylic resin and the polyimide resin, and the acrylic resin and the polyimide resin are compatible with each other in a solvent.

[0022] <Acrylic resin> The acrylic resin is a polymer of an acrylic acid ester or a methacrylic acid ester. Specific examples include poly(meth)acrylic acid esters such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymers, methyl methacrylate-(meth)acrylic acid ester copolymers, methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymers, and methyl (meth)acrylate-styrene copolymers. Acrylic resins containing methyl methacrylate as the main component are particularly preferred. The acrylic resin may also incorporate a glutarimide structural unit or a lactone ring structural unit. The stereoregularity of the polymer is not particularly limited, and may be any of isotactic, syndiotactic, and atactic.

[0023] Introducing a glutarimide structure into an acrylic polymer such as methyl methacrylate tends to increase the glass transition temperature of the acrylic resin. Furthermore, since the acrylic resin contains an imide structure, its compatibility with polyimides may be improved. For example, even if a specific polyimide resin is not compatible with polymethyl methacrylate, it may be compatible with an acrylic resin having a glutarimide structure. Acrylic resins having a glutarimide structure can be obtained by heating and melting polymethyl methacrylate resin and treating it with an imidizing agent, as described in JP 2010-261025 A, for example.

[0024] When the acrylic polymer has a glutarimide structure, the glutarimide content may be 3% by weight or more, 10% by weight or more, 20% by weight or more, 30% by weight or more, or 50% by weight or more. The glutarimide content can be calculated by determining the imidization ratio Im = B / (A + B) from the H-NMR spectrum of the acrylic resin, where A is the area of ​​the peak derived from the O-CH3 proton of methyl methacrylate and B is the area of ​​the peak derived from the N-CH3 proton of glutarimide, and then converting the imidization ratio into weight. Introducing a glutarimide structure into the acrylic resin is expected to improve compatibility with polyimides and the elastic modulus of the resulting molded product.

[0025] From the viewpoint of heat resistance of the resin composition, molded article and resin film of the present invention, the glass transition temperature of the acrylic resin is preferably 100°C or higher, more preferably 110°C or higher, and may be 115°C or higher or 120°C or higher.

[0026] From the viewpoints of solubility in organic solvents, compatibility with the polyimide resin, and film strength, the weight-average molecular weight (polystyrene equivalent) of the acrylic resin is preferably 5,000 to 5,000,000, more preferably 10,000 to 2,000,000, and may be 30,000 to 1,000,000 or 50,000 to 500,000. If the molecular weight of the acrylic resin is too small, the durability of the resulting film may be reduced. If the molecular weight of the acrylic resin is too high, film-forming properties may be poor.

[0027] From the viewpoint of the thermal stability and light stability of the resin composition, molded article, and resin film of the present invention, it is preferable that the acrylic resin has a low content of reactive functional groups such as ethylenically unsaturated groups and carboxy groups. The iodine value of the acrylic resin is preferably 10.16 g / 100 g (0.4 mmol / g) or less, more preferably 7.62 g / 100 g (0.3 mmol / g) or less, and even more preferably 5.08 g / 100 g (0.2 mmol / g) or less. The acid value of the acrylic resin is preferably 0.4 mmol / g or less, more preferably 0.3 mmol / g or less, and even more preferably 0.2 mmol / g or less. A low acid value tends to enhance the stability of the acrylic resin and improve its compatibility with polyimide resins.

[0028] An example of the acrylic resin is "Parapet G (manufactured by Kuraray Co., Ltd., weight average molecular weight 100,000, Tg: 101° C.)".

[0029] <Polyimide resin> Polyimide resins (hereinafter sometimes simply referred to as "PI") are polymers having structural units represented by general formula (I) and are obtained by cyclodehydration of polyamic acid obtained by addition polymerization of tetracarboxylic dianhydride (hereinafter sometimes simply referred to as "acid dianhydride") and diamine. That is, polyimide resins are polycondensates of tetracarboxylic dianhydride and diamine, and have a structure derived from tetracarboxylic dianhydride (tetracarboxylic dianhydride component) and a structure derived from diamine (diamine component). Polyimide resins can also be synthesized by condensation via decarboxylation of diisocyanate and tetracarboxylic dianhydride.

[0030] [ka]

[0031] In general formula (I), X is a tetravalent organic group, and Y is a divalent organic group. X is a tetracarboxylic dianhydride residue, which is an organic group obtained by removing two carboxy anhydride groups from a tetracarboxylic dianhydride represented by the following general formula (II). Y is a diamine residue, which is an organic group obtained by removing two amino groups from a diamine represented by the following general formula (III). When a polyimide resin is synthesized using a diisocyanate, Y is a diisocyanate residue, which is an organic group obtained by removing two isocyanate groups from a diisocyanate compound.

[0032] [ka]

[0033] In other words, the polyimide resin contains a structural unit represented by the following general formula (IIa) and a structural unit represented by the following general formula (IIIa), and the tetracarboxylic dianhydride-derived structure (IIa) and the diamine-derived structure (IIIa) form an imide bond, thereby having the structural unit represented by general formula (I).

[0034] [ka]

[0035] The polyimide resin may contain, in addition to the imide structural unit represented by general formula (I), an amide structural unit represented by the following general formula (IV) or a structural unit containing an amide structure and an imide structure represented by (V). A polyimide resin containing, in addition to the imide structural unit, an amide structural unit or a structural unit containing an amide structure and an imide structure is also called a polyamideimide resin.

[0036] [ka]

[0037] In general formulas (IV) and (V), Y and Z are divalent organic groups, and W is a trivalent organic group. Y is a diamine residue, as in general formula (I). Z is a dicarboxylic acid residue, which is an organic group obtained by removing two carboxy groups from a dicarboxylic acid represented by the following general formula (VI). W is a tricarboxylic acid anhydride residue, which is an organic group obtained by removing a carboxy anhydride group and a carboxy group from a tricarboxylic acid anhydride represented by the following general formula (VII). In the synthesis of polyamide-imide resins, dicarboxylic acid derivatives such as dicarboxylic acid dichlorides, dicarboxylic acid anhydrides, and dicarboxylic acid esters represented by general formula (VI'), and tricarboxylic acid anhydride derivatives such as tricarboxylic acid anhydride chloride represented by general formula (VII') are preferably used instead of dicarboxylic acids or tricarboxylic acid anhydrides.

[0038] [ka]

[0039] The diamine-derived structure represented by the general formula (IIIa) above and the dicarboxylic acid-derived structure represented by the following general formula (VIa) form an amide bond to form an amide structural unit represented by the general formula (IV), and the diamine-derived structure represented by the general formula (IIIa) and the tricarboxylic acid anhydride-derived structure represented by the following general formula (VIIa) form an imide bond and an amide bond to form a structural unit containing an amide structure and an imide structure represented by the general formula (V). That is, the polyamideimide resin contains one or more structures selected from the dicarboxylic acid-derived structure (VIa) or the tricarboxylic acid anhydride-derived structure (VIIa), a tetracarboxylic acid dianhydride-derived structure (IIa), and a diamine-derived structure (IIIa).

[0040] [ka]

[0041] The polyamide-imide resin contains, for example, a structure of the following general formula (VIII) in which a diamine-derived structure (IIIa) is bonded to both ends of a dicarboxylic acid-derived structure (VIa).

[0042] [ka]

[0043] In general formula (VIII), Y1 and Y2 are diamine residues, and Z1 is a dicarboxylic acid residue. In general formula (IX), Y3 and Y4 are diamine residues, and Z2 is a tricarboxylic acid anhydride residue. When the moiety [-Y1-NH-CO-Z1-CO-NH-Y2-] in general formula (VIII) or the moiety [-Y3-N-(CO)2-Z2-CO-NH-Y4-] in general formula (IX) is considered as a single divalent organic group, this divalent organic group can be considered as a diamine residue Y containing two amide bonds. That is, in general formula (I), a polyimide resin containing an amide bond in the diamine residue Y is a polyamideimide resin, and polyamideimide resins can be considered a type of polyimide resin. Hereinafter, unless otherwise specified, the term "polyimide resin" includes "polyamideimide resin."

[0044] As described above, the polyimide resin contains a diamine-derived structure (diamine component) and a tetracarboxylic dianhydride-derived structure (tetracarboxylic dianhydride component). The polyimide resin used in this embodiment has a diamine-derived structure such as CF3-O-, -(CF2-O) n -, -O-(CF2-CF2-O) n - (where n is an integer of 1 to 20).

[0045] (diamine) The diamine component of the polyimide used in the present invention is CF3-O-, -(CF2-O) n -, -O-(CF2-CF2-O) n - (where n is an integer of 1 to 20). By having such a structure in which a fluorinated methyl structure or a fluorinated methylene structure is directly bonded to an oxygen atom, it is expected that the decomposition property of the fluorine-containing compound in the environment will be improved and the environmental persistence of the fluorine-containing compound will be significantly reduced.

[0046] CF3-O-, -(CF2-O) n -, -O-(CF2-CF2-O) n- (where n is an integer of 1 to 20), the diamine may include perfluoroalkoxy-substituted benzidines. Examples of perfluoroalkoxy-substituted benzidines include 2-(trifluoromethoxy)benzidine, 3-(trifluoromethoxy)benzidine, 2,3-bis(trifluoromethoxy)benzidine, 2,5-bis(trifluoromethoxy)benzidine, 2,6-bis(trifluoromethoxy)benzidine, 2,3,5-tris(trifluoromethoxy)benzidine, 2,3,6-tris(trifluoromethoxy)benzidine, 2,3,5,6-tetrakis(trifluoromethoxy)benzidine, 2,2'-bis(trifluoromethoxy)benzidine, 3,3'-bis(trifluoromethoxy)benzidine, 2,3'-bis(trifluoro methoxy)benzidine, 2,2',3-tris(trifluoromethoxy)benzidine, 2,3,3'-tris(trifluoromethoxyl)benzidine, 2,2',5-tris(trifluoromethoxy)benzidine, 2,2',6-tris(trifluoromethoxy)benzidine, 2,3',5-tris(trifluoromethoxy)benzidine, 2,3',6-tris(trifluoromethoxy)benzidine, 2,2',3,3'-tetrakis(trifluoromethoxy)benzidine, 2,2',5,5'-tetrakis(trifluoromethoxy)benzidine, 2,2',6,6'-tetrakis(trifluoromethoxy)benzidine, and the like.

[0047] CF3-O-, -(CF2-O) n -, -O-(CF2-CF2-O) n- (where n is an integer of 1 to 20), other examples of diamines having a structure selected from the above-listed list include phenylenediamines having perfluoroalkoxy substitutions, such as 1,2-diamino-4-(trifluoromethoxy)benzene (TFMOBzo), 1,3-diamino-4-(trifluoromethoxy)benzene (TFMOBzm), 1,4-diamino-2-(trifluoromethoxy)benzene, 1,4-diamino-2,3-bis(trifluoromethoxy)benzene, 1,4-diamino-2,5-bis(trifluoromethoxy)benzene, 1,4-diamino-2,6-bis(trifluoromethoxy)benzene, 1,4-diamino-2,3,5-tris(trifluoromethoxy)benzene, and 1,4-diamino-2,3,5,6-tetrakis(trifluoromethoxy)benzene.

[0048] From the viewpoints of mechanical strength and polymerizability, perfluoroalkoxy-substituted benzidines are preferred. Among them, from the viewpoints of the solubility of the polyimide resin in organic solvents and compatibility with acrylic resins, perfluoroalkoxy-substituted benzidines having a perfluoroalkoxy group at the 2- or 3-position of the biphenyl are preferred, with 2,2'-bis(trifluoromethoxy)benzidine (hereinafter referred to as "TFMOB"), 3,3'-bis(trifluoromethoxy)benzidine, and 2,3'-bis(trifluoromethoxy)benzidine being more preferred, with TFMOB being particularly preferred. By having a trifluoromethoxy group at the 2- or 3-position of the biphenyl, not only is the electron-withdrawing property of the trifluoromethoxy group reduced in π electron density, but the steric hindrance of the trifluoromethoxy group inhibits π-π stacking between benzene rings, shifting the absorption edge wavelength to shorter wavelengths and reducing coloration of the polyimide. Furthermore, by having trifluoromethoxy groups at the 2- and 2'-positions, the steric hindrance of the trifluoromethoxy groups twists the bond between the two benzene rings of the biphenyl, reducing the planarity of the π-conjugation, thereby shifting the absorption edge wavelength to shorter wavelengths and reducing the coloration of the polyimide.

[0049] CF3-O-, -(CF2-O) relative to 100 mol% of the total amount of diamine components n -, -O-(CF2-CF2-O)n The content of the diamine having a structure selected from -CF3-O-, -(CF2-O) (where n is an integer of 1 to 20) is preferably 10 mol% or more, more preferably 30 mol% or more, even more preferably 50 mol% or more, and may be 60 mol% or more, 70 mol% or more, or 80 mol% or more, or even 100 mol%. n -, -O-(CF2-CF2-O) n - (where n is an integer of 1 to 20), coloration of the film is suppressed, and mechanical strength such as pencil hardness, elastic modulus, breaking strength, and breaking elongation may be improved.

[0050] Polyimide contains CF3-O-, -(CF2-O) as diamine components. n -, -O-(CF2-CF2-O) n -CF3-O-, -(CF2-O) (where n is an integer of 1 to 20) may be contained. n -, -O-(CF2-CF2-O) n- (where n is an integer of 1 to 20) Examples of diamines that do not have a structure selected from the group consisting of p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, and 4,4'-diaminodiphenyl sulfone. Fluorene, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, 9,9-bis(4-amino-3-methylphenyl)fluorene, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2-di(3-aminophenyl)propane, 2,2-di(4-aminophenyl)propane, 2-(3-aminophenyl) -2-(4-aminophenyl)propane, 1,1-di(3-aminophenyl)-1-phenylethane, 1,1-di(4-aminophenyl)-1-phenylethane, 1-(3-aminophenyl)-1-(4-aminophenyl)-1-phenylethane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminobenzoyl)benzene, 1,3-bis(4-aminobenzoyl)benzene Benzene, 1,4-bis(3-aminobenzoyl)benzene, 1,4-bis(4-aminobenzoyl)benzene, 1,3-bis(3-amino-α,α-dimethylbenzyl)benzene, 1,3-bis(4-amino-α,α-dimethylbenzyl)benzene, 1,4-bis(3-amino-α,α-dimethylbenzyl)benzene, 1,4-bis(4-amino-α,α-dimethylbenzyl)benzene, 2,6-bis(3-aminophenoxy)benzonitrile, 2,6-bis(3-aminophenoxy)pyridine, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, 2,2-bis[4-( 1,3-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene, 1,3-bis[4-(4-aminophenoxy)benzoyl]benzene, 1,4-bis[4-(3-aminophenoxy)benzoyl]benzene, 1,4-bis[4-(4-aminophenoxy)benzoyl]benzene, 1,3-bis[4-(3-aminophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)-α,α-dimethyl benzyl]benzene, 1,4-bis[4-(3-aminophenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(4-aminophenoxy)-α,α-dimethylbenzyl]benzene, 4,4'-bis[4-(4-aminophenoxy)benzoyl]diphenyl ether, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzophenone, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]diphenyl sulfone, 4,4'-bis[4-(4-aminophenoxy)phenoxy]diphenyl sulfone, 3,3'-diamino-4,4'-diphenoxybenzophenone, 3,3'-diamino-4,4'-dibiphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 3,3'-diamino-4-biphenoxybenzophenone, 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindan, 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindan, 1,3-bis(3-aminopropyl)tetramethyldisiloxane, 1,3-bis(4-aminobutyl)tetramethyldisiloxane, α,ω-bis(3-aminopropyl)polydimethylsiloxane, α,ω-bis(3-aminobutyl)polydimethylsiloxane, bis(aminomethyl)ether, bis(2-aminoethyl)ether, bis(3-aminopropyl)ether, bis(2-aminomethoxy)ethyl]ether, bis[2-(2-aminoethoxy)ethyl]ether, bis[2-(3-aminoprotoxy)ethyl]ether, 1,2-bis(aminomethoxy)ethane, 1,2-bis(2-aminoethoxy)ethane, 1,2-bis[2-(aminomethoxy)ethoxy]ethane, 1,2-bis[2-(2-aminoethoxy)ethoxy]ethane, ethylene glycol bis(3-aminopropyl)ether, diethylene glycol bis(3-aminopropyl)ether, triethylene glycol bis(3-aminopropyl) Ether, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,2-diaminocyclohexane, isophoronediamine, 1,3-diaminocyclohexane, 1,4- Examples include diaminocyclohexane, trans-1,4-diaminocyclohexane, 1,2-di(2-aminoethyl)cyclohexane, 1,3-di(2-aminoethyl)cyclohexane, 1,4-di(2-aminoethyl)cyclohexane, bis(4-aminocyclohexyl)methane, 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, and 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane.

[0051] For example, diamines include CF3-O-, -(CF2-O) n -, -O-(CF2-CF2-O) nThe use of diaminodiphenyl sulfone in addition to a diamine having a structure selected from - (where n is an integer of 1 to 20) may improve the solubility in solvents and transparency of the polyimide resin. Among diaminodiphenyl sulfones, 3,3'-diaminodiphenyl sulfone (3,3'-DDS) and 4,4'-diaminodiphenyl sulfone (4,4'-DDS) are preferred. 3,3'-DDS and 4,4'-DDS may be used in combination.

[0052] When a diamine having a sulfonic acid group is used, from the viewpoint of the transparency and mechanical strength of the polyimide resin, the ratio of the structure derived from the diamine having a sulfonic acid group to the total amount of the structure derived from the diamine is preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and may be 10 mol% or more, 12 mol% or more, or 15 mol% or more. From the viewpoint of the solubility of the polyimide resin, the ratio of the structure derived from the diamine having a sulfonic acid group to the total amount of the structure derived from the diamine is preferably 50 mol% or less, more preferably 30 mol% or less, and may be 20 mol% or less, 10 mol% or less, or may be absent. The amount of diamine having a sulfonic acid group required to achieve compatibility with a polyester resin may vary depending on the polyester resin, the type of diamine having a sulfonic acid group, etc.

[0053] For example, diamines include CF3-O-, -(CF2-O) n -, -O-(CF2-CF2-O) n - (where n is an integer of 1 to 20), the use of a fluorene-containing diamine may improve the solubility of the polyimide resin in solvents, transparency, mechanical strength, and compatibility with acrylic resins. Preferred fluorene-containing diamines are 9,9-bis(4-aminophenyl)fluorene, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, and 9,9-bis(4-amino-3-methylphenyl)fluorene, and these may be used in combination.

[0054] When a diamine containing fluorene is used, from the viewpoint of the transparency and mechanical strength of the polyimide resin, the ratio of the diamine-derived structure having a sulfonic acid group to the total amount of diamine-derived structures is preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and may be 10 mol% or more, 12 mol% or more, or 15 mol% or more. From the viewpoint of the solubility of the polyimide resin, the ratio of the diamine-derived structure having a sulfonic acid group to the total amount of diamine-derived structures is preferably 50 mol% or less, more preferably 30 mol% or less, and may be 20 mol% or less, 10 mol% or less, or may be absent. The amount of diamine having a sulfonic acid group necessary to achieve compatibility with a polyester resin may vary depending on the polyester resin and the type of diamine having a sulfonic acid group.

[0055] (Tetracarboxylic acid dianhydride) The tetracarboxylic dianhydride component of the polyimide resin used in this embodiment is not particularly limited. From the viewpoint of compatibility between the polyimide resin and the acrylic resin, it is preferable that the tetracarboxylic dianhydride component of the polyimide resin contains an alicyclic tetracarboxylic dianhydride. The alicyclic tetracarboxylic dianhydride has at least one alicyclic structure and may contain both an alicyclic ring and an aromatic ring in one molecule. The alicyclic ring may be polycyclic or may have a spiro structure. Furthermore, from the viewpoint of the mechanical properties of the polyimide resin, it is preferable that the tetracarboxylic dianhydride component of the polyimide resin contains a structure derived from a tetracarboxylic dianhydride having a fluorene structure. The alicyclic tetracarboxylic dianhydride and the tetracarboxylic dianhydride having a fluorene structure may be used alone or in combination.

[0056] Examples of alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, meso-butane-1,2,3,4-tetracarboxylic dianhydride, 1,1'-Bicyclohexane-3,3',4,4'tetracarboxylic acid-3,4:3',4'-dianhydride, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid dianhydride, 2,2'-binorbornane-5,5',6,6'tetracarboxylic acid dianhydride, 3-(carboxymethyl)-1,2,4-cyclopentanetricarboxylic acid 1,4:2,3-dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, 4 -(2,5-Dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid anhydride, cyclohexane-1,4-diylbis(methylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate), 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, 5,5'-[cyclohexylidenebis(4,1-phenyleneoxy)]bis-1,3-isobenzofurandione, 5-isobenzyl Benzofurancarboxylic acid, 1,3-dihydro-1,3-dioxo-,5,5'-[1,4-cyclohexanediylbis(methylene)] ester, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride, 3,5,6-tricarboxynorbornane-2-acetic acid 2,3:5,6-dianhydride, decahydro-1,4,5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic dianhydride, tricyclo[6.4.0.0(2,7)]dodecane-1,8:2,7-tetracarboxylic dianhydride, octahydro-1H,3H,8H,10H-biphenyleno[4a,4b-c:8a,8b-c']difuran-1,3,8,10-tetrone, ethylene glycol bis(hydrogenated trimellitic anhydride) ester, decahydro[2]benzopyrano[6,5,4,-def][2]benzopyran-1,3,6,8-tetrone, etc.

[0057] Among alicyclic tetracarboxylic dianhydrides, from the viewpoint of the transparency and mechanical strength of the polyimide, 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 1,2,3,4-cyclopentanetetracarboxylic dianhydride (CPDA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (H-PMDA) or 1,1'-bicyclohexane-3,3',4,4'tetracarboxylic acid-3,4:3',4'-dianhydride (H-BPDA) are preferred, and 1,2,3,4-cyclobutanetetracarboxylic dianhydride is particularly preferred.

[0058] When an alicyclic tetracarboxylic dianhydride is used, from the viewpoint of improving compatibility between the acrylic resin and the polyimide resin, the content of the alicyclic tetracarboxylic dianhydride relative to 100 mol% of the total amount of tetracarboxylic dianhydride components is preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and may be 6 mol% or more, 7 mol% or more, 8 mol% or more, 9 mol% or more, 10 mol% or more, 12 mol% or more, or 15 mol% or more. The amount of alicyclic tetracarboxylic dianhydride required to ensure compatibility with the acrylic resin may vary depending on the type of acrylic resin and the amount of alicyclic tetracarboxylic dianhydride. For example, when the alicyclic tetracarboxylic dianhydride is 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), the content of CBDA relative to 100 mol% of the total amount of tetracarboxylic dianhydride components is preferably 6 mol% or more, more preferably 8 mol% or more, and even more preferably 10 mol% or more.

[0059] From the viewpoint of ensuring the solubility of the polyimide resin in organic solvents, the content of the alicyclic tetracarboxylic dianhydride relative to the total amount of tetracarboxylic dianhydride components (100 mol%) is preferably 80 mol% or less, more preferably 78 mol% or less, and even more preferably 76 mol% or less, and may be 74 mol% or less, 72 mol% or less, 70 mol% or less, 65 mol% or less, 60 mol% or less, 55 mol% or less, or 50 mol% or less. To make the polyimide resin soluble in a low-boiling halogen-containing solvent such as methylene chloride, the content of the alicyclic tetracarboxylic dianhydride is preferably 45 mol% or less, more preferably 40 mol% or less, and may be 35 mol% or less.

[0060] Tetracarboxylic dianhydrides having a fluorene structure include 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride (BPF-PPA), N,N'-(9H-fluoren-9-ylidene-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxamide] (FDA-ATA), 5,5'-(9H-fluoren-9-ylidenebis(2-methyl- 4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylate] (TBIS.MPN), 5,5'-spiro[9H-fluorene-9,9'-[9H]xanthene]-3',6'-diylbis(1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylate (TBIS.RXN), spiro[11H-difuro[3,4-b:3',4'-i]xanthene-11,9'-[9H]fluorene]-1,3,7,9-tetrone (SFDA), and the like.

[0061] Among tetracarboxylic dianhydrides with a fluorene structure, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride (BPF-PPA), 5,5'-(9H-fluoren-9-ylidenebis(2-methyl-4,1-phenylene)bis[1,3-dihydro-1H-fluorene]bis(2-methyl-4,1-phenylene)bis(1,3-dihydro-1H-fluorene) ... ,3-dioxo-5-isobenzofurancarboxylate] (TBIS.MPN), 5,5'-spiro[9H-fluorene-9,9'-[9H]xanthene]-3',6'-diylbis(1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylate (TBIS.RXN), and spiro[11H-difuro[3,4-b:3',4'-i]xanthene-11,9'-[9H]fluorene]-1,3,7,9-tetrone (SFDA) are preferred.

[0062] When a tetracarboxylic dianhydride having a fluorene structure is used, from the viewpoint of improving compatibility between the polyimide resin and the polyester resin, the ratio of the structure derived from the tetracarboxylic dianhydride having a fluorene structure to the total amount of structures derived from the tetracarboxylic dianhydride is preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and may be 10 mol% or more, 12 mol% or more, or 15 mol% or more. From the viewpoint of transparency of the polyimide resin, the ratio of the structure derived from the tetracarboxylic dianhydride having a fluorene structure to the total amount of structures derived from the tetracarboxylic dianhydride is preferably 70 mol% or less, more preferably 60 mol% or less, and may be 50 mol% or less, 30 mol% or less, or may be absent. The amount of tetracarboxylic dianhydride having a fluorene structure required to achieve compatibility with the polyester resin may vary depending on the polyester resin and the type of tetracarboxylic dianhydride having a fluorene structure.

[0063] The polyimide resin may contain, as a tetracarboxylic acid dianhydride component, a tetracarboxylic acid dianhydride other than an alicyclic tetracarboxylic acid dianhydride and a tetracarboxylic acid dianhydride having a fluorene structure. Examples of tetracarboxylic acid dianhydrides other than those mentioned above that have improved compatibility with acrylic resins include bisphenol-type tetracarboxylic acid dianhydrides, tetracarboxylic acid dianhydrides having an ester bond, tetracarboxylic acid dianhydrides having an ether bond, aromatic tetracarboxylic acid dianhydrides, and chain aliphatic tetracarboxylic acid dianhydrides.

[0064] Bisphenol-type tetracarboxylic dianhydrides are tetracarboxylic dianhydrides obtained by reacting two hydroxy groups of bisphenols with 5-iodoisobenzofuran-1,3-dione, etc. Among bisphenol-type tetracarboxylic dianhydrides, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride is preferred from the viewpoint of the solubility and mechanical properties of polyimide resins.

[0065] When a bisphenol tetracarboxylic dianhydride is used, from the viewpoint of improving compatibility between the polyimide resin and the acrylic resin, the ratio of structures derived from the bisphenol tetracarboxylic dianhydride to the total amount of structures derived from the tetracarboxylic dianhydride is preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and may be 10 mol% or more, 12 mol% or more, or 15 mol% or more. From the viewpoint of transparency of the polyimide resin, the ratio of structures derived from the bisphenol tetracarboxylic dianhydride to the total amount of structures derived from the tetracarboxylic dianhydride is preferably 70 mol% or less, more preferably 60 mol% or less, and may be 50 mol% or less, 30 mol% or less, or may be absent. The amount of bisphenol tetracarboxylic dianhydride required to ensure compatibility with the acrylic resin may vary depending on the type of acrylic resin and bisphenol tetracarboxylic dianhydride.

[0066] The tetracarboxylic dianhydride having an ester structure is a bis(trimellitic anhydride) ester, and is represented by the following general formula (1).

[0067] [ka]

[0068] In general formula (1), A is any divalent organic group, and at both ends of A, a carboxy group is bonded to a carbon atom of A. Specific examples of the divalent organic group A include the following (i) to (viii). (However, R 1 represents an alkyl group having 1 to 4 carbon atoms, m represents 0 or an integer of 1 to 4, and R 2a and R 2b are the same or different and represent an alkyl group having 1 to 4 carbon atoms; n1 and n2 are the same or different and represent an integer of 0 or 1 to 4; R 3a and R 3b are the same or different and represent a substituent; k1 and k2 are the same or different and represent an integer of 0 or 1 to 4; R 4 represents an alkyl group having 1 to 4 carbon atoms, j represents 0 or an integer of 1 to 10, and p represents an integer of 1 to 10.) When a tetracarboxylic acid dianhydride having an ester structure also has a fluorene structure, it is treated as a tetracarboxylic acid dianhydride having a fluorene structure.

[0069] The groups represented by formulas (i) to (viii) are groups obtained by removing two hydroxyl groups from diols. For example, the group represented by formula (i) is a group obtained by removing two hydroxyl groups from a hydroquinone derivative which may have a substituent on the benzene ring.

[0070] [ka]

[0071] R in formulas (iii), (iv), and (v) 3a and R 3bare the same or different and represent a substituent. The substituent is not particularly limited, but from the viewpoint of the solubility of the polyimide resin, R 3a and R 3b is preferably an alkyl group having 1 to 10 carbon atoms, a phenyl group, an alkoxy group, or a halogen.

[0072] The tetracarboxylic dianhydride having an ester structure is preferably an aromatic ester, and among the above (i) to (viii), A is preferably (i) to (v). Among these, (i) to (iv) are preferred, with (i) and (ii) being particularly preferred. When A is a group represented by general formula (i), from the viewpoint of the mechanical properties of the resin composition, general formula (1) is preferably 1,4-phenylenebis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (TAHQ) represented by the following formula (1-1).

[0073] [ka]

[0074] When A in general formula (1) is a group represented by formula (ii), from the viewpoint of the solubility of the polyimide resin, general formula (1) is preferably 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diylbis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (TAHMBP) represented by the following formula (1-2).

[0075] [ka]

[0076] When A in general formula (1) is a group represented by formula (iii), from the viewpoint of the solubility of the polyimide resin, general formula (1) is preferably bisphenol Z bis(trimellitic anhydride) (BPZ-TME) represented by the following formula (1-3).

[0077] [ka]

[0078] When A in general formula (1) is a group represented by formula (iv), from the viewpoint of the solubility of the polyimide resin, general formula (1) is preferably 5,5'-[cyclododecylidenebis(2-methyl-4,1-phenylene)]bis(1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylate) (TBIS-DMPN) represented by the following formula (1-4).

[0079] [ka]

[0080] When a tetracarboxylic dianhydride having an ester structure is used, from the viewpoint of improving compatibility between the polyimide resin and the acrylic resin, the ratio of structures derived from the tetracarboxylic dianhydride having an ester structure to the total amount of structures derived from the tetracarboxylic dianhydride is preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and may be 10 mol% or more, 12 mol% or more, or 15 mol% or more. From the viewpoint of weather resistance of the polyimide resin, the ratio of structures derived from the tetracarboxylic dianhydride having an ester structure to the total amount of structures derived from the tetracarboxylic dianhydride is preferably 70 mol% or less, more preferably 60 mol% or less, and may be 50 mol% or less, 30 mol% or less, or may be absent. The amount of tetracarboxylic dianhydride having an ester structure necessary to ensure compatibility with the acrylic resin may vary depending on the type of acrylic resin and the tetracarboxylic dianhydride having an ester structure.

[0081] Examples of the tetracarboxylic dianhydride having an ether bond include 3,4'-oxydiphthalic anhydride, 4,4'-oxydiphthalic anhydride, etc. Among the tetracarboxylic dianhydrides having an ether bond, 4,4'-oxydiphthalic anhydride is preferred from the viewpoint of solubility of polyimide resins.

[0082] When a tetracarboxylic dianhydride having an ether bond is used, from the viewpoint of mechanical strength, the content of the tetracarboxylic dianhydride having an ether bond relative to the total amount of structures derived from the tetracarboxylic dianhydride is preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and may be 10 mol% or more, 12 mol% or more, or 15 mol% or more. From the viewpoint of ensuring solubility of the polyimide resin in organic solvents, the ratio of structures derived from the tetracarboxylic dianhydride having an ether bond relative to the total amount of structures derived from the tetracarboxylic dianhydride is preferably 50 mol% or less, more preferably 40 mol% or less, and may be 30 mol% or less, 20 mol% or less, or may be zero. The amount of tetracarboxylic dianhydride having an ether bond necessary to ensure compatibility with a polyester resin may vary depending on the type of polyester resin and the type of tetracarboxylic dianhydride having an ether bond.

[0083] Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, mellophanic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 5,5'-dimethylmethylenebis(phthalic anhydride), 2,3,6,7-naphthalenetetracarboxylic dianhydride, carboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, terphenyltetracarboxylic acid dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 2,2-bis(4-hydroxyphenyl)propanedibenzoate-3,3',4,4'-tetracarboxylic acid dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid dianhydride, and the like.

[0084] Examples of aromatic tetracarboxylic dianhydrides other than those mentioned above include 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 1,3-bis[(3,4-dicarboxy)benzoyl]benzene dianhydride, 1,4-bis[(3,4-dicarboxy)benzoyl]benzene dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride, phenyl}ketone dianhydride, 4,4'-bis[4-(1,2-dicarboxy)phenoxy]biphenyl dianhydride, 4,4'-bis[3-(1,2-dicarboxy)phenoxy]biphenyl dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl}sulfide dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}sulfide dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, and bis(1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylic acid)-1,4-phenylene ester.

[0085] Among the aromatic tetracarboxylic dianhydrides, pyromellitic dianhydride and mellophanic dianhydride are preferred, with pyromellitic dianhydride being particularly preferred, from the viewpoint of the mechanical strength of the resin composition.

[0086] When an aromatic tetracarboxylic dianhydride is used, from the viewpoint of mechanical strength, the ratio of structures derived from the aromatic tetracarboxylic dianhydride to the total amount of structures derived from the tetracarboxylic dianhydride is preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and may be 10 mol% or more, 12 mol% or more, or 15 mol% or more. From the viewpoint of transparency of the polyimide resin, the ratio of structures derived from the aromatic tetracarboxylic dianhydride to the total amount of structures derived from the tetracarboxylic dianhydride is preferably 50 mol% or less, more preferably 40 mol% or less, and may be 30 mol% or less, 20 mol% or less, or may be absent. The amount of aromatic tetracarboxylic dianhydride required to ensure compatibility with a polyester resin may vary depending on the type of polyester resin and aromatic tetracarboxylic dianhydride, etc.

[0087] Furthermore, as the tetracarboxylic dianhydride, a chain aliphatic tetracarboxylic dianhydride such as ethylene tetracarboxylic dianhydride, 1,2,3,4-butane tetracarboxylic dianhydride, meso-butane-1,2,3,4-tetracarboxylic dianhydride, etc. may be used.

[0088] When a chain aliphatic tetracarboxylic dianhydride is used, from the viewpoint of transparency, the content of the chain aliphatic tetracarboxylic dianhydride relative to the total amount of structures derived from the tetracarboxylic dianhydride is preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and may be 10 mol% or more, 12 mol% or more, or 15 mol% or more. From the viewpoint of mechanical strength of the polyimide resin, the ratio of structures derived from the chain aliphatic tetracarboxylic dianhydride relative to the total amount of structures derived from the tetracarboxylic dianhydride is preferably 50 mol% or less, more preferably 40 mol% or less, and may be 30 mol% or less, 20 mol% or less, or may be absent. The amount of chain aliphatic tetracarboxylic dianhydride required to ensure compatibility with a polyester resin may vary depending on the type of polyester resin and the chain aliphatic tetracarboxylic dianhydride, etc.

[0089] (dicarboxylic acid) Examples of dicarboxylic acids include aliphatic dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-oxybisbenzoic acid, 4,4'-biphenyldicarboxylic acid, and 2-fluoroterephthalic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-hexahydroterephthalic acid, hexahydroisophthalic acid, 1,3-cyclopentanedicarboxylic acid, and bi(cyclohexyl)-4,4'-dicarboxylic acid; and heterocyclic dicarboxylic acids such as 2,5-thiophenedicarboxylic acid and 2,5-furandicarboxylic acid.

[0090] From the viewpoint of the solubility of the polyimide resin, the dicarboxylic acid is preferably an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid, and more preferably an aromatic dicarboxylic acid. Among the aromatic dicarboxylic acids, terephthalic acid, isophthalic acid, 4,4'-biphenyldicarboxylic acid, and 4,4'-oxybisbenzoic acid are preferred, with terephthalic acid and isophthalic acid being preferred, and terephthalic acid being more preferred. Among the alicyclic dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid and bi(cyclohexyl)-4,4'-dicarboxylic acid are preferred, with 1,4-cyclohexanedicarboxylic acid being more preferred.

[0091] In the preparation of polyimide resins and polyamic acids as precursors thereof, dicarboxylic acid derivatives such as dicarboxylic acid dichlorides, dicarboxylic acid esters, and dicarboxylic acid anhydrides may be used in place of dicarboxylic acids.

[0092] (Tricarboxylic acid anhydride) Examples of tricarboxylic acid anhydrides include trimellitic acid, 2-fluorotrimellitic acid, 5-fluorotrimellitic acid, 6-fluorotrimellitic acid, 2,5-difluorotrimellitic acid, 2,6-difluorotrimellitic acid, 5,6-difluorotrimellitic acid, and 2,5,6-trifluorotrimellitic acid.

[0093] In the preparation of polyimide resins and polyamic acids as precursors thereof, tricarboxylic acid anhydride derivatives such as tricarboxylic acid anhydride chlorides and tricarboxylic acid anhydride esters may be used in place of tricarboxylic acid anhydrides.

[0094] (Polyimide resin with excellent environmental safety) In order to obtain a polyimide resin in which the environmental decomposition property of fluorine-containing compounds is improved and the environmental persistence of fluorine-containing compounds is significantly reduced, a structure derived from a diamine having a specific fluorine structure, The total content of fluorine atoms contained in the structure derived from the tetracarboxylic dianhydride having the specific fluorine structure, the structure of the dicarboxylic acid having the specific fluorine structure, and the structure derived from the tricarboxylic anhydride having the specific fluorine structure is preferably less than 500 mg, more preferably less than 300 mg, still more preferably less than 100 mg, and even more preferably less than 50 mg, per kg of polyimide resin. Here, diamines having a specific fluorine structure, tetracarboxylic dianhydrides having a specific fluorine structure, dicarboxylic acids having a specific fluorine structure, and tricarboxylic anhydrides having a specific fluorine structure refer to diamines having a fully fluorinated methyl group (CF3-) or methylene group (-CF2-), tetracarboxylic dianhydrides having a fully fluorinated methyl group (CF3-) or methylene group (-CF2-), dicarboxylic acids having a fully fluorinated methyl group (CF3-) or methylene group (-CF2-), and tricarboxylic anhydrides having a fully fluorinated methyl group (CF3-) or methylene group (-CF2-), excluding substances containing only the structural element CF3-X or X'-CF2-X. (wherein X is an -OR or -NRR' structure, X' is any one of -H, -CH3, aromatic, -C(=O)-, -OR'', -SR'', NR''R'''', and R, R', R'', R'' are any one of -H, -CH3, -CH2-, aromatic, and -C(=O)-)

[0095] More preferably, the ratio of diamine-derived structures having a CF3- group directly bonded to an aromatic ring or a -C(CF3)2- group directly bonded to an aromatic ring to the total amount of diamine-derived structures is less than 0.5 mol %, the ratio of tetracarboxylic acid dianhydride-derived structures having a CF3- group directly bonded to an aromatic ring or a -C(CF3)2- group directly bonded to an aromatic ring to the total amount of tetracarboxylic acid dianhydride-derived structures is less than 0.5 mol %, the ratio of dicarboxylic acid-derived structures having a CF3- group directly bonded to an aromatic ring or a -C(CF3)2- group directly bonded to an aromatic ring to the total amount of dicarboxylic acid-derived structures is less than 0.5 mol %, and the ratio of tricarboxylic acid anhydride-derived structures having a CF3- group directly bonded to an aromatic ring or a -C(CF3)2- group directly bonded to an aromatic ring to the total amount of tricarboxylic acid anhydride-derived structures is less than 0.5 mol %. Examples of diamines and tetracarboxylic dianhydrides having a CF3- group directly bonded to an aromatic ring or a -C(CF3)2- group directly bonded to an aromatic ring include 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 9,9-bis(trifluoromethyl)xanthenetetracarboxylic dianhydride, 9-trifluoromethylxanthenetetracarboxylic dianhydride, 2,2'-bis(trifluoromethyl)benzidine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane.

[0096] In addition, -CF2 (-CF2-) of the polyimide resin composition m The content of the diamine-derived structure having -CF2- (m is an integer of 1 or more) is less than 0.5 mol% based on the total amount of the diamine-derived structures, and the polyimide resin composition k The content of the structure derived from the tetracarboxylic dianhydride having CF2- (k is an integer of 1 or more) is more preferably less than 0.5 mol % based on the total amount of the structures derived from the tetracarboxylic dianhydride.

[0097] (Preparation of Polyimide Resin) The reaction of diamine with tetracarboxylic dianhydride produces polyamic acid as a polyimide precursor, and the polyamic acid is then cyclized (imidized) to produce polyimide. The method for preparing polyamic acid is not particularly limited, and any known method can be used. For example, a polyamic acid solution can be obtained by dissolving diamine and tetracarboxylic dianhydride in approximately equimolar amounts (molar ratio of 90:100 to 110:100) in an organic solvent and stirring the mixture.

[0098] The concentration of the polyamic acid solution is usually 5 to 35% by weight, and preferably 10 to 30% by weight. When the concentration is within this range, the polyamic acid obtained by polymerization has an appropriate molecular weight, and the polyamic acid solution has an appropriate viscosity.

[0099] In the polymerization of polyamic acid, a method of adding tetracarboxylic dianhydride to diamine is preferred to suppress ring-opening of tetracarboxylic dianhydride. When adding multiple types of diamines or multiple types of tetracarboxylic dianhydrides, they may be added all at once or in multiple portions. The physical properties of the polyimide resin can also be controlled by adjusting the order of addition of the monomers.

[0100] The organic solvent used in the polymerization of polyamic acid is not particularly limited as long as it does not react with diamines and tetracarboxylic dianhydrides and can dissolve polyamic acid. Examples of organic solvents include urea-based solvents such as methylurea and N,N-dimethylethylurea; sulfoxide or sulfone-based solvents such as dimethyl sulfoxide, diphenyl sulfone, and tetramethyl sulfone; amide-based solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N,N'-diethylacetamide, N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, and hexamethylphosphoric triamide; alkyl halide solvents such as chloroform and dichloromethane; aromatic hydrocarbon solvents such as benzene and toluene; and ether-based solvents such as tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, dimethyl ether, diethyl ether, and p-cresol methyl ether. These solvents are typically used alone or in combination as needed. From the viewpoint of the solubility and polymerization reactivity of the polyamic acid, DMAc, DMF, NMP, etc. are preferably used.

[0101] Polyimide resins are obtained by the dehydration and cyclization of polyamic acid. One method for preparing polyimide resins from polyamic acid solutions involves adding a dehydrating agent, an imidization catalyst, etc. to the polyamic acid solution and allowing imidization to proceed in the solution. Heating the polyamic acid solution can also be used to accelerate the imidization process. Mixing a solution containing the polyimide resin produced by imidization of polyamic acid with a poor solvent results in the polyimide resin being precipitated as a solid. Isolating the polyimide resin as a solid allows impurities generated during polyamic acid synthesis, as well as residual dehydrating agents and imidization catalysts, to be washed away with the poor solvent, preventing discoloration and increased yellowness of the polyimide resin. Furthermore, isolating the polyimide resin as a solid allows the use of solvents suitable for film formation, such as low-boiling point solvents, when preparing solutions for producing molded products such as films.

[0102] The molecular weight of the polyimide (weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC)) is preferably 10,000 to 1,000,000, more preferably 20,000 to 500,000, and even more preferably 40,000 to 300,000. If the molecular weight is too small, the strength of the film may be insufficient. If the molecular weight is too large, the compatibility with resins other than polyimide may be poor and the film formability may be poor.

[0103] The polyimide resin is preferably soluble in a solvent, particularly preferably in a non-amide solvent such as a ketone solvent or an alkyl halide solvent, and more preferably in methylene chloride. The solubility in a solvent is preferably exhibited at 60°C or less, more preferably at 40°C or less, and even more preferably at 23°C or less. When a polyimide resin is soluble in a solvent, it means that it is soluble at a concentration of 5% by weight or more. In one embodiment, the polyimide resin is soluble in methylene chloride. Methylene chloride has a low boiling point and allows easy removal of residual solvent during film production, so the use of a polyimide resin soluble in methylene chloride can be expected to improve the productivity of resin films.

[0104] From the viewpoint of the thermal stability and light stability of the resin composition and film, it is preferable that the polyimide has low reactivity. The acid value of the polyimide is preferably 0.4 mmol / g or less, more preferably 0.3 mmol / g or less, and even more preferably 0.2 mmol / g or less. The acid value of the polyimide may be 0.1 mmol / g or less, 0.05 mmol / g or less, or 0.03 mmol / g or less. From the viewpoint of reducing the acid value, it is preferable that the polyimide has a high imidization rate. A low acid value tends to increase the stability of the polyimide and improve its compatibility with resins other than polyimide.

[0105] <Preparation of Resin Composition> The acrylic resin and the polyimide resin are mixed to prepare a resin composition. Generally, the acrylic resin is not compatible with other resins. However, in this embodiment, as described above, the polyimide resin is a CF3-O-, -(CF2-O) n -, -O-(CF2-CF2-O) n - (where n is an integer of 1 to 20), the acrylic resin and the polyimide resin exhibit compatibility. Whether the acrylic resin and the polyimide resin are compatible in the film state is confirmed by preparing a 50 μm thick film containing the acrylic resin and the polyimide resin. If the film is transparent and has a haze of 10% or less, the acrylic resin and the polyimide resin are judged to be compatible, and if the film's haze exceeds 10%, the acrylic resin and the polyimide resin are judged not to be compatible.

[0106] Furthermore, whether or not the acrylic resin and polyimide resin are compatible in a solvent can be confirmed by dissolving the resin composition in a solvent that dissolves both polyimide-based resins and acrylic resins, such as N,N-dimethylformamide (DMF) or methylene chloride, to a solids concentration of 10% by weight. If the resin solution is transparent and not phase-separated, the acrylic resin and polyimide-based resin in the resin composition are deemed to be compatible. If the resin solution separates into two or more phases or is cloudy, the acrylic resin and polyimide resin are deemed not to be compatible. The haze of a solution containing the acrylic resin and polyimide-based resin, measured with an optical path length of 1 cm, is preferably 10% or less, more preferably 5% or less, even more preferably 2% or less, and particularly preferably 1% or less.

[0107] The acrylic resin and polyimide resin are compatible with each other at any ratio. However, the resin film of the present invention contains the polyimide resin in a range of 0.1% by weight to 25% by weight of the total of the acrylic resin and the polyimide resin. The ratio of the acrylic resin to the polyimide resin is not particularly limited as long as it is within this range. The higher the acrylic resin ratio, the higher the Abbe number of the resin composition. Furthermore, when the resin composition is processed into a film, the film tends to have a higher total light transmittance, a lower yellowness index (YI), and better optical properties. The higher the polyimide resin ratio, the higher the refractive index of the resin composition. Furthermore, when the resin composition is processed into a film by a solution casting method, the solvent dries quickly, resulting in excellent productivity. Furthermore, the film tends to have excellent mechanical properties, such as a high elastic modulus and pencil hardness, and also to have high heat resistance. From the viewpoint of the balance between optical properties, mechanical properties, and heat resistance, the ratio of polyimide resin to the total of acrylic resin and polyimide resin is preferably 0.1% by weight or more and 25% by weight or less, more preferably 0.5% by weight or more and 20% by weight or less, and even more preferably 1.0% by weight or more and 10% by weight or less.

[0108] The resin composition may be a simple mixture of acrylic resin and polyimide resin precipitated as solids, or may be a kneaded mixture of acrylic resin and polyimide resin. Furthermore, when a polyimide resin solution is mixed with a poor solvent to precipitate the polyimide resin, an acrylic resin may be mixed into the solution, and the resin composition, in which the acrylic resin and polyimide resin are mixed, may be precipitated as a solid (powder).

[0109] The resin composition may be a mixed solution containing an acrylic resin and a polyimide resin. The method for mixing the resins is not particularly limited, and the resins may be mixed in a solid state or in a liquid state to form a mixed solution. An acrylic resin solution and a polyimide resin solution may be prepared separately, and then the two may be mixed to form a mixed solution of the acrylic resin and the polyimide resin.

[0110] The solvent for the solution containing the acrylic resin and the polyimide resin may be any solvent that dissolves both the acrylic resin and the polyimide resin, and examples thereof include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; ether solvents such as tetrahydrofuran and 1,4-dioxane; ketone solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, diethyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone; and alkyl halide solvents such as chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, dichlorobenzene, and methylene chloride.

[0111] Generally, polyimide resins have low solubility in solvents and are often soluble only in highly polar solvents. Therefore, amide-based solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone are preferred as solvents. The use of these solvents can improve the compatibility between acrylic resins and polyimide resins. Furthermore, from the perspective of solvent removability when producing molded articles such as films, low-boiling non-amide solvents are preferred. Ketone-based solvents and alkyl halide solvents are preferred because they have excellent solubility in both acrylic resins and polyimide resins and have low boiling points, making it easy to remove residual solvent during film production. The use of these solvents that readily dissolve polyimide resins reduces the viscosity of the resulting solution, resulting in improved handleability and reduced appearance defects such as unevenness when producing molded articles by film formation, etc.

[0112] Furthermore, a solution of a resin composition containing an acrylic resin and a polyimide resin tends to have a lower solution viscosity than a solution of a polyimide resin alone at the same solid content concentration, which is advantageous in terms of ease of handling during transportation and the like, high coatability, and reduction of unevenness in film thickness.

[0113] The resin composition may contain organic or inorganic low molecular weight compounds, polymeric compounds (e.g., epoxy resins), etc. The resin composition may contain flame retardants, ultraviolet absorbers, crosslinking agents, dyes, pigments, surfactants, leveling agents, plasticizers, fine particles, fiber reinforcement materials, sensitizers, etc. The fine particles include organic fine particles such as polystyrene and polytetrafluoroethylene, and inorganic fine particles such as colloidal silica, carbon, and layered silicates, and may have a porous or hollow structure. The fiber reinforcement materials include carbon fibers, glass fibers, aramid fibers, etc.

[0114] [Molded products and films] The above composition can be used to form various molded articles. Molding methods include melt methods such as injection molding, transfer molding, press molding, blow molding, inflation molding, calendar molding, and melt extrusion molding. Resin compositions containing acrylic resin and polyimide resin tend to have lower melt viscosity than polyimide resin alone, and are excellent in moldability in injection molding, transfer molding, press molding, melt extrusion molding, and the like.

[0115] Furthermore, a solution of a resin composition containing an acrylic resin and a polyimide resin tends to have a lower solution viscosity than a solution of a polyimide resin alone at the same solid content concentration, which is advantageous in terms of ease of handling during transportation and the like, high coatability, and reduction of unevenness in film thickness.

[0116] In the present invention, the molded article is a film. The film molding method may be either a melting method or a solution casting method, but the solution casting method is preferred from the viewpoint of producing a film excellent in transparency and uniformity. In the solution casting method, a solution containing the above-mentioned acrylic resin and polyimide resin is applied to a support, and the solvent is dried and removed to obtain a film.

[0117] The resin film of the present invention includes a dissolving step in which a resin composition containing an acrylic resin and a polyimide resin is dissolved in a solvent to prepare a resin solution, a coating step in which the resin solution is applied to a support to form a coating film, a drying step in which the coating film is dried so that the residual solvent is 5 to 20 wt %, and a peeling step in which the dried coating film is peeled off from the support to obtain a green sheet, thereby producing a resin film with good film appearance.

[0118] Each step will be explained below. (melting process) The solvent for dissolving the resin composition containing the acrylic resin and the polyimide resin is not particularly limited as long as it exhibits solubility in both the acrylic resin and the polyimide resin. Examples include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; ether solvents such as tetrahydrofuran and 1,4-dioxane; ketone solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, diethyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone; and alkyl halide solvents such as chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, dichlorobenzene, and methylene chloride. Ketone solvents and alkyl halide solvents are preferred because of their excellent solubility in both the acrylic resin and the polyimide resin, their low boiling points, and the ease of removing residual solvent during film production. These solvents may be used alone or in combination.

[0119] The solids concentration of a solution of a resin composition containing an acrylic resin and a polyimide resin (resin solution) may be appropriately set depending on the molecular weight of the acrylic resin and polyimide resin, the thickness of the resin film, the film-forming environment, and other factors. The solids concentration is preferably 5 to 30% by weight, more preferably 8 to 20% by weight. The resin solution may contain resin components and additives other than the resin composition. Additives may include organic or inorganic low-molecular-weight compounds, polymeric compounds (e.g., epoxy resins), flame retardants, UV absorbers, crosslinking agents, dyes, pigments, surfactants, leveling agents, plasticizers, organic fine particles such as polystyrene and polytetrafluoroethylene, inorganic fine particles such as colloidal silica, carbon, and layered silicates, porous or hollow fine particles of these organic and inorganic fine particles, fiber reinforcing materials such as carbon fiber, glass fiber, and aramid fiber, and sensitizers.

[0120] A solution of a resin composition containing an acrylic resin and a polyimide resin tends to have a lower solution viscosity than a solution of a polyimide resin with the same solid content, which makes the resin solution easier to handle, such as for transportation, and has excellent coatability, which is advantageous in reducing unevenness in film thickness.

[0121] (Coating process) The resin solution can be applied to a support by known methods using a bar coater or comma coater. Examples of the support that can be used include glass substrates, metal substrates such as SUS, metal drums, metal belts, and plastic films. From the viewpoint of improving productivity, it is preferable to use endless supports such as metal drums and metal belts, or long plastic films as the support and produce the film by roll-to-roll processing. When using a plastic film as the support, it is sufficient to select an appropriate material that is insoluble in the solvent of the resin solution (dope). Examples of plastic materials include films made of polymers such as polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, and polycarbonate polymers and acrylic polymers such as polymethyl methacrylate.

[0122] (drying process) A resin composition coating film can be produced by applying a resin solution to a substrate and then drying the solvent. While the drying temperature and drying time are not particularly limited, drying is preferably performed so that the residual solvent in the coating film is 5% by weight to 20% by weight, and more preferably 10% by weight to 15% by weight. By keeping the residual solvent amount within the above range, a self-supporting coating film can be obtained without excessive stretching or rupture during the subsequent peeling step. The residual solvent in the coating film refers to the amount of solvent contained in the coating film, and can be determined by dissolving the coating film in a solvent and quantifying it using an analytical instrument such as a gas chromatograph, or by heating the coating film to remove the solvent and measuring the weight change before and after.

[0123] (peeling process) A resin sheet (hereinafter referred to as a green sheet) having a residual solvent content of 5 to 20 wt % can be produced by peeling and removing the substrate from the coating film of the resin composition containing an acrylic resin and a polyimide resin. A peeling roll may be used to peel and remove the substrate.

[0124] It is preferable to heat a green sheet of a resin composition containing an acrylic resin and a polyimide resin to further dry the solvent. The heating temperature is not particularly limited as long as it can remove the solvent and prevent discoloration of the resulting film. It is set appropriately between room temperature and approximately 250°C, with 50°C to 220°C being preferred. The heating temperature may be increased in stages. To promote solvent removal, heating may be performed under reduced pressure. High-boiling point solvents, such as amide solvents such as N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc), can also be dried under a nitrogen atmosphere as long as the temperature is below the decomposition temperature of the solvent-soluble resin. The compatibility of the acrylic resin and polyimide resin results in a lower glass transition temperature compared to the polyimide resin alone. This allows the solvent to be removed at a lower drying temperature than the polyimide resin alone, resulting in reduced film discoloration.

[0125] Although acrylic resin films may have low toughness, the strength of the film may be improved by using a compatible system of acrylic resin and polyimide resin. Stretching may be performed in one or more directions to improve the mechanical strength of the film. Stretching a film orients the polymer chains in the stretching direction, improving the strength of the film in the in-plane direction and tending to suppress the occurrence of breakage or cracks in the film.

[0126] In particular, in a compatible system of acrylic resin and polyimide resin, the tensile modulus in the stretching direction tends to increase, and the flex resistance tends to improve accordingly.

[0127] For example, films used as cover films or substrate materials for foldable displays are repeatedly folded along the folding axis at the same location, and therefore are required to have high mechanical strength in a direction perpendicular to the folding axis. Therefore, by arranging the film so that the stretching direction is perpendicular to the folding axis, the film is less likely to break or crack at the folding location even when repeatedly folded, and a device with high bending resistance can be provided.

[0128] The film stretching method is not particularly limited. Various stretching methods such as free-end stretching, fixed-end stretching, free-end shrinkage, and fixed-end shrinkage are used. Among them, free-end stretching, typified by a method in which a film being transported is stretched in the transport direction by using the difference in peripheral speed between nip rolls before and after the film (so-called longitudinal stretching), or fixed-end stretching, typified by a method in which a film being transported is stretched in a direction perpendicular to the transport direction using a tenter clip device or the like (so-called transverse stretching), is preferred from the viewpoint of unidirectionally orienting the molecules in the film.

[0129] The film stretching conditions (e.g., stretching direction, stretching temperature, stretching ratio) are not particularly limited. Stretching can be performed in various directions, such as the length direction, width direction, thickness direction, and oblique direction. The stretching temperature is not particularly limited, but is about ±40°C of the glass transition temperature of the film, and may be about 120 to 300°C, 150 to 250°C, or 180 to 230°C. The stretching ratio is not particularly limited, but is about 1 to 200%, and may be about 5 to 150%, 10 to 120%, or 20 to 100%. The tensile modulus in the stretching direction tends to increase as the stretching ratio increases. On the other hand, if the stretching ratio is excessively high, the mechanical strength in the direction perpendicular to the stretching direction tends to decrease, which may result in poor handling of the film.

[0130] The film may be biaxially stretched to increase the strength in any in-plane direction. The biaxial stretching may be simultaneous biaxial stretching or sequential biaxial stretching. In biaxial stretching, the stretching ratio in one direction and the stretching ratio in the perpendicular direction may be the same or different. When a difference in stretching ratio is made, the mechanical strength in the direction with the larger stretching ratio tends to be relatively larger. When a biaxially stretched film with anisotropic stretching ratio is used in a foldable device, it is preferable to arrange it so that the direction with the larger stretching ratio is perpendicular to the folding axis.

[0131] The thickness of the film is not particularly limited and may be appropriately set depending on the application. The thickness of the film is, for example, 5 to 300 μm. From the viewpoint of obtaining a film that is both self-supporting and flexible and has high transparency, the thickness of the film is preferably 10 μm to 200 μm, and may be 30 μm to 150 μm, 40 μm to 100 μm, or 50 μm to 80 μm. The thickness of the film used as a cover film for a display is preferably 30 μm or more. When the film is stretched, the thickness after stretching is preferably within the above range.

[0132] The haze of the film is preferably 10% or less, more preferably 5% or less, even more preferably 4% or less, and may be 3.5% or less, 3% or less, 2% or less, or 1% or less. The lower the haze of the film, the less the image resolution is impaired when the film is used as a display film, which is preferable. As described above, since the acrylic resin and the polyimide resin are compatible, a film with low haze and high transparency can be obtained. It is preferable that the resin composition obtained by mixing the acrylic resin and the polyimide resin has a haze of 10% or less when a film with a thickness of 50 μm is produced.

[0133] The total light transmittance of the film is preferably 85% or more, more preferably 86% or more, even more preferably 87% or more, particularly preferably 88% or more, and may be 89% or more, or even 90% or more. The resin composition obtained by mixing an acrylic resin and a polyimide resin preferably has a total light transmittance of 85% or more when produced into a film having a thickness of 50 μm. A high total light transmittance is preferable because when the resin film is used as a display film, the brightness of the display increases.

[0134] The yellowness index (YI) of the film is not particularly limited, but is preferably 20.0 or less, more preferably 10.0 or less, and even more preferably 5.0 or less, and may be 4.0 or less, 3.0 or less, 2.0 or less, 1.0 or less, or 0.0 or less. If the yellowness index (YI) is greater than 20.0, when the film is used as a display film, the display will take on a yellowish tinge, and the color reproducibility of the display will be reduced. It is preferable that the resin composition obtained by mixing a polyimide resin and a polyester resin has a yellowness index of 20.0 or less when a film having a thickness of 50 μm is produced. As described above, by mixing a polyimide and a polyester resin, a film with less coloration and a small YI can be obtained compared to when a polyimide resin is used alone.

[0135] The refractive index of the film is not particularly limited, but is preferably 1.450 to 1.600, more preferably 1.460 to 1.580, even more preferably 1.470 to 1.570, particularly preferably 1.480 to 1.560, and most preferably 1.490 to 1.550.

[0136] The Abbe number vd of the film is not particularly limited, but from the viewpoint of reducing chromatic aberration (reducing color bleeding), it is preferably 34 to 60, more preferably 38 to 57, and even more preferably 40 to 55. Here, the Abbe number is calculated from the refractive index at wavelengths of 486.1 nm, 587.6 nm, and 656.3 nm using the following formula: νd=(nd-1) / (nF-nC) nd: refractive index at a wavelength of 587.56 nm, nF: refractive index at a wavelength of 486.13 nm, nC: Refractive index at a wavelength of 656.27 nm.

[0137] The in-plane birefringence ΔN of the film is preferably less than 0.020, more preferably less than 0.015, even more preferably less than 0.010, and particularly preferably less than 0.006. Here, the in-plane birefringence ΔN is the difference between the refractive index nx in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction) and the refractive index ny in the in-plane direction perpendicular to the slow axis (i.e., the fast axis direction), and the in-plane birefringence ΔN multiplied by the film thickness is the front retardation of the film. The smaller the in-plane birefringence ΔN, the better the color reproducibility of the display when the film is used as a display film, which is preferable.

[0138] The birefringence ΔP in the thickness direction of the film is preferably less than 0.020, more preferably less than 0.015, even more preferably less than 0.010, and particularly preferably less than 0.006. Here, the birefringence ΔP in the thickness direction is the difference between the average of the refractive index nx in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction) and the refractive index ny in the direction perpendicular to the slow axis in the plane (i.e., the fast axis direction), and the refractive index nz in the thickness direction, and the thickness retardation of the film is the birefringence ΔP in the thickness direction multiplied by the thickness of the film. The smaller the birefringence ΔP in the thickness direction, the better the color reproducibility of the display when the film is used as a display film, which is preferable.

[0139] The film may exhibit an inverse dispersion wavelength characteristic in which the retardation increases with the wavelength of the measurement light, a positive wavelength dispersion characteristic in which the retardation decreases with the wavelength of the measurement light, or a flat wavelength dispersion characteristic in which the retardation changes little with the wavelength of the measurement light. When the retardation of the resin film exhibits an inverse dispersion wavelength characteristic, the ratio Re(450) / Re(550) of the retardation at a wavelength of 450 nm to the retardation at a wavelength of 550 nm, Re(450) / Re(550), is preferably 0.5 or more and less than 1.0, more preferably 0.7 or more and 0.95 or less, and particularly preferably 0.8 or more and 0.9 or less, from the viewpoint of antireflection properties.

[0140] From the viewpoint of film strength, the tensile modulus of the film at room temperature is preferably 2.0 GPa or more, more preferably 3.0 GPa or more, and even more preferably 4.0 GPa or more. The tensile modulus may be anisotropic, and the difference between the modulus of elasticity in a first direction (first modulus) in which the modulus of elasticity is maximum in the film plane and the modulus of elasticity in a direction perpendicular to the first direction (second modulus) is preferably 5% or more. When the difference between the first modulus and the second modulus is 5% or more, mechanical properties such as bending resistance and pencil hardness tend to be improved due to the orientation of the polymer chains. The pencil hardness of the film is preferably 6B or more, preferably 4B or more, and may be 2B or more, F or more, or 2H or more. In a compatible system of acrylic resin and polyimide resin, pencil hardness is unlikely to decrease even when the ratio of acrylic resin is increased. Therefore, a film with little coloration and excellent transparency can be provided without significantly reducing the excellent mechanical strength unique to polyimide resin.

[0141] Films formed from resin compositions containing acrylic resins and polyimide resins are suitable for use as display materials because they have little coloring and high transparency. In particular, films with high mechanical strength can be applied to surface components such as display cover windows. When used in practice, the film of the present invention may be provided with an antistatic layer, an easy-adhesion layer, a hard coat layer, an antireflection layer, or the like on its surface. [Example]

[0142] The following examples will be used to further explain the present invention, but the present invention is not limited to these examples.

[0143] [Preparation of polyimide resin] A separable flask was charged with 21.6 g of 2,2'-bis(trifluoromethoxy)benzidine (TFMOB) and 172 g of N,N-dimethylformamide and stirred under a nitrogen atmosphere to obtain a diamine solution. To this solution, 3.6 g of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) and 19.7 g of 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF) were added and stirred for 12 hours under a nitrogen atmosphere to obtain a polyamic acid solution with a solids concentration of 18%. Pyridine was added as an imidization catalyst to the polyamic acid solution, and after complete dispersion, acetic anhydride was added and stirred at 90°C for 3 hours. After cooling to room temperature, 2-propyl alcohol was added dropwise while stirring the solution to precipitate the polyimide resin. IPA was then added, and after stirring for approximately 30 minutes, the solution was suction filtered using a Kiriyama funnel. The obtained solid was washed with IPA and then dried for 12 hours in a vacuum oven set at 120°C to obtain a polyimide resin (weight average molecular weight Mw = 270,000).

[0144] Examples 1 to 4: Resin films containing acrylic resin and polyimide resin [Preparation of a solution containing a resin composition] The above polyimide resin and a commercially available polymethyl methacrylate resin (a copolymer of methyl methacrylate / methyl acrylate (monomer ratio 87 / 13), glass transition temperature 101°C, acid value 0.0 mmol / g) as an acrylic resin were added to methylene chloride in the weight ratios shown in Table 2 to prepare a methylene chloride solution with a resin content of 20 wt %.

[0145] [Preparation of resin film] A solution containing the above resin composition was applied to a 305mm x 220mm non-alkali glass substrate (200mm wide). The solution was then dried at room temperature under a 350mm x 250mm x 20mm aluminum tray until the film became tack-free. The film was then heated and dried at 50°C for 10 minutes, and the glass was peeled off to obtain a green sheet. The resulting green sheet was then fixed to a metal frame on all four sides and further dried at 80°C for 10 minutes, 110°C for 10 minutes, and 140°C for 10 minutes to produce a film with a thickness of 50±5μ. "Tack-free" refers to the state in which the liquid does not stick to the finger when gently placed on the film surface during drying.

[0146] <Comparative Examples 1 and 2> A resin film was produced in the same manner as in the example, except that the acrylic resin and the polyimide resin were used in the ratio shown in Table 2.

[0147] <Comparative Example 3> A resin film was produced in the same manner as in the example, except that the acrylic resin and polycarbonate resin (Teijin's "Panlite L1225Y") were used in the ratio shown in Table 2.

[0148] [evaluation] <Haze and total light transmittance> The haze and total light transmittance (TT:%) of the resin film were measured using a haze meter "HZ-V3" manufactured by Suga Test Instruments in accordance with JIS K7136 and JIS K7361-1. The measurements were performed using a D65 light source.

[0149] <Yellowness (YI)> The yellowness index (YI) of the resin film was measured according to JIS K7373 using a spectrophotometer "SC-P" manufactured by Suga Test Instruments. <Refractive index and Abbe number> The refractive index of the resin film was measured at wavelengths of 404 nm, 594 nm, and 827 nm using a Metricon prism coupler "Model 2010 / M." Cauchy dispersion fitting was performed on the refractive index at each wavelength, and the refractive index (nd) at 587.6 nm was taken as the refractive index of the resin film. The refractive index (nF) at 486.1 nm and the refractive index (nC) at 656.3 nm were also determined using Cauchy dispersion fitting, and the Abbe number (νd) of the resin film was calculated using the following formula. νd=(nd-1) / (nF-nC)

[0150] <Weight average molecular weight> The resin was dissolved in the eluent shown in Table 1 so that the resin concentration was 0.15 wt % relative to the solution, and then the weight average molecular weight was measured under the following conditions. [Table 1] <Glass transition temperature> Test specimens were prepared by cutting out strips of 25 mm length x 5 mm width from the unstretched films obtained in the Examples and Comparative Examples. Using a dynamic viscoelasticity measuring device (Rheogel-E4000, manufactured by UBM), the storage modulus E' and loss modulus E" were measured in tension mode while heating from 30°C to 300°C at an initial chuck distance of 15 mm, a frequency of 10 Hz, and a heating rate of 10°C / min. E" / E' (= tan δ) was plotted against temperature, and the temperature at which the maximum value was reached was taken as the glass transition temperature (Tg). [Table 2]

[0151] The resin films shown in Examples 1 to 4 have a short time until they become tack-free, less than 12 minutes, and can be said to have excellent productivity. Furthermore, the addition of polyimide resin to acrylic resin increased the glass transition temperature, i.e., improved heat resistance. On the other hand, in Comparative Example 1, the time until they became tack-free was long, resulting in poor productivity and poor heat resistance. In Comparative Example 2, the productivity and heat resistance were good, but the film had a low Abbe number. From the viewpoint of reducing chromatic aberration (reducing color bleeding), the Abbe number of the film is preferably 34 to 60. In Comparative Example 3, the polycarbonate resin was not compatible, and a smooth and transparent film could not be obtained.

Claims

1. A resin composition containing an acrylic resin and a polyimide resin, The polyimide resin has a diamine-derived structure and a tetracarboxylic dianhydride-derived structure, and the diamine-derived structure is CF ３ -O-, -(CF ２ -O) ｎ -, -O-(CF ２ -CF ２ -O) ｎ - (where n is an integer of 1 to 20), the polyimide resin is contained in the resin composition in an amount of 0.1% by weight or more and 25% by weight or less based on the total weight of the acrylic resin and the polyimide resin, and the acrylic resin and the polyimide resin are compatible with each other in a solvent.

2. 2. The resin composition according to claim 1, wherein the acrylic resin is an acrylic resin containing methyl methacrylate as a main component.

3. The polyimide resin has a ratio of CF directly bonded to an aromatic ring to the total amount of the diamine-derived structure. ３ - group or -C(CF ３ ) ２ The ratio of the structure derived from the diamine having - is less than 0.5 mol %, and the ratio of the CF directly bonded to the aromatic ring to the total amount of the structure derived from the tetracarboxylic dianhydride is ３ - group or -C(CF ３ ) ２ 2. The resin composition according to claim 1, wherein the ratio of the structure derived from the tetracarboxylic dianhydride having - is less than 0.5 mol %.

4. The CF ３ -O-, -(CF ２ -O) ｎ -, -O-(CF ２ -CF ２ -O) ｎ - (wherein n is an integer of 1 to 20) is selected from 2,2'-bis(trifluoromethoxy)benzidine, 3,3'-bis(trifluoromethoxy)benzidine, and 2,3'-bis(trifluoromethoxy)benzidine. The resin composition according to claim 1,

5. 2. The resin composition according to claim 1, wherein the polyimide resin contains a structure derived from an alicyclic tetracarboxylic dianhydride as a structure derived from a tetracarboxylic dianhydride, and the structure derived from the alicyclic tetracarboxylic dianhydride accounts for 1 to 80 mol% of the total amount of structures derived from the tetracarboxylic dianhydride.

6. 2. The resin composition according to claim 1, wherein the polyimide resin contains, as the structure derived from the tetracarboxylic dianhydride, a structure derived from the tetracarboxylic dianhydride having a fluorene structure.

7. A molded article comprising the resin composition according to any one of claims 1 to 6.

8. A resin film comprising the resin composition according to any one of claims 1 to 6.

9. The resin film according to claim 8, which has a total light transmittance of 90% or more, a haze of 1% or less, and a yellowness index of 1.0 or less.

10. 7. A method for producing a resin film, comprising: a dissolving step of dissolving the resin composition according to claim 1 in a solvent to prepare a resin solution; a coating step of applying the resin solution onto a support to form a coating film; a drying step of drying the coating film so that the residual solvent is 5 to 20 wt %; and a peeling step of peeling the dried coating film from the support to obtain a green sheet.

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