Phase difference film and method for manufacturing phase difference film, and polarizing plate, image display device and information processing device

Abstract

A phase difference film is composed of one or more layers, wherein at least one of the layers comprises a composition of a polyester resin having aryl esters in the side chains, and the in-plane phase difference Ro(450) and Ro(550) of the aforementioned layer containing the aforementioned polyester resin are related by Ro(450) / Ro(550) ≥ 1.22, and the aforementioned layer is extended.

Description

[Technical Field]

[0001] The present invention relates to a phase difference film, a polarizing plate using the phase difference film, and an image display device. The phase difference film has negative inherent birefringence, large phase difference visibility, and excellent coating properties, so it can be appropriately used as a negative A plate, positive B plate, and positive C plate of a 1 / 2λ plate, a 1 / 4λ phase difference film, a viewing angle compensation film, an anti-reflection film, etc. [Previous Technology]

[0002] In display devices such as liquid crystal displays (LCDs), retardation films are used for optical compensation to prevent contrast reduction and color distortion caused by viewing angle. Furthermore, in organic EL (electroluminescent) display devices, unlike LCDs, retardation films are used to suppress contrast reduction caused by reflection of external light. Because the retardation film must be designed with an optimal three-dimensional refractive index according to the application of these display devices, the following materials are combined: materials with positive intrinsic birefringence and materials with negative intrinsic birefringence.

[0003] Materials with positive intrinsic birefringence generally have a wide range of material selectivity, mainly using materials such as triacetate cellulose, polycarbonate, and polycyclic olefins.

[0004] On the other hand, the selection of materials with negative intrinsic birefringence is initially limited, including known materials such as polymethyl methacrylate (PMMA) polymers and polystyrene polymers (Patent Documents 1 and 2). However, these polymers are prone to cracking due to insufficient heat resistance and brittleness, making them difficult to process. PMMA polymers, in particular, have low phase difference manifestation, making it difficult to obtain phase difference films. Polystyrene polymers, on the other hand, are difficult to process as a single layer, therefore a multilayer film with a rigid polycarbonate polymer has been proposed (Patent Document 3). However, such multilayer films have issues with the required toughness during molding, and their practicality is insufficient. [Prior Art Documents] (Patent Documents)

[0005] Patent Document 1: Japanese Patent Application Publication No. 2003-043253; Patent Document 2: Japanese Patent Application Publication No. 2007-24940; Patent Document 3: Japanese Patent Application Publication No. 2014-149508; Patent Document 4: Japanese Patent Application Publication No. Hei 11-52131 [Summary of the Invention]

[0006] [Problem to be Solved by the Invention] A phase retardation film with excellent toughness and negative intrinsic birefringence could be considered, such as a polyester resin film with cycloids in the side chains. However, due to insufficient manifestation of phase retardation, it is not possible to make the phase retardation film thin.

[0007] Thin retardation films, including those with liquid crystal layers, have been practically applied (Patent Document 4). The liquid crystal layer is created by coating a liquid crystal compound onto a substrate film and aligning it, thus enabling the display of a phase retardation. However, manufacturing such retardation films requires numerous complex steps, including an alignment process and a transfer step of the liquid crystal layer onto a polarizing plate. Furthermore, these complex steps not only necessitate the use of expensive liquid crystal compounds but also generally result in low yield rates. Consequently, the manufacturing cost of retardation films intended for mass production becomes very high. Therefore, a thin retardation film that is less expensive and also helps reduce manufacturing costs is sought.

[0008] The object of the present invention is to provide a phase retardation thin film and a method for manufacturing the same, a polarizing plate having the aforementioned phase retardation thin film, an image display device having the aforementioned polarizing plate, and an information processing device having the aforementioned image display device. The phase retardation thin film exhibits high phase retardation visibility, excellent processing performance, lower cost, and is thin. [Technical Means for Solving the Problem]

[0009] After conducting research in order to achieve the aforementioned problem, the inventors discovered that polyester resins containing aryl cyclohexane rings in the side chains exhibit a large negative intrinsic birefringence, and that a phase difference film can be formed inexpensively by film preparation and stretching, which is easy to process as a film, thus completing the present invention.

[0010] In other words, the present invention is as follows. [1] A phase retardation film, which is composed of one or more layers, and at least one of such layers comprises a composition containing a polyester resin having aryl compounds as side chains, and the relationship between the in-plane phase differences Ro(450) and Ro(550) of the aforementioned layer containing the aforementioned polyester resin is Ro(450) / Ro(550) ≥ 1.22, and having the aforementioned layer extended. [2] The phase retardation film as described in [1], wherein the aforementioned composition exhibits negative intrinsic birefringence. [3] The phase difference film as described in [1] or [2], wherein the aforementioned polyester resin contains a specific polyester resin comprising the following components as monomers: a dicarboxylic acid component represented by the following general formula (1), and at least one diol component selected from the group consisting of a diol component (A) represented by the following general formula (2), a diol component (B) represented by the following general formula (3), and a diol component (C) represented by the following general formula (4), and k is 1 or more in at least a portion or all of the dicarboxylic acid component represented by the following general formula (1); in formula (1), R1a and R1b independently represent phenyl or naphthyl, k independently represents an integer from 0 to 4, and X1 independently represents a C1-8 alkyl group; In formula (2), Z independently represents phenyl or naphthyl, R2a and R2b independently represent inert substituents, p independently represents integers from 0 to 4, R3 independently represents alkyl, alkoxy, cycloalkoxy, aryloxy, arylalkoxy, aryl, cycloalkyl, arylalkyl, halogen atom, nitro, or cyano, q independently represents integers from 0 to 2, R4 independently represents C2-6 alkyl, and r independently represents integers greater than 1; in formula (3), R5a and R5b independently represent inert substituents, m independently represents integers from 0 to 4, and X2 independently represents C1-8 alkyl; in formula (4), X3 represents C2-8 alkyl. [4] The phase difference film as described in [3], wherein the aforementioned polyester resin comprises a specific polyester resin comprising the following components as monomers: a dicarboxylic acid component in which R1a and R1b are 2-naphthyl and k is 1 and X1 is ethyl in the aforementioned general formula (1), and at least one diol component selected from the group consisting of a diol component (A) in which Z is phenyl and p and q are 0 and R4 is ethyl and r is 1 and a diol component (C) in which X3 is ethyl in the aforementioned general formula (4). [5] The phase difference film as described in any one of [1] to [4], wherein the composition of the aforementioned polyester resin containing the aforementioned aryl ester side chain is a polymer alloy comprising: the aforementioned polyester resin containing the aforementioned aryl ester side chain, and a polycarbonate resin.[6] The phase retardation film as described in any one of [1] to [5], wherein the aforementioned phase retardation film is a multilayer film comprising: a layer comprising the aforementioned polyester resin, and a resin layer having positive intrinsic birefringence. [7] The phase retardation film as described in [6], wherein the aforementioned resin layer having positive intrinsic birefringence comprises a polyamide resin. [8] The phase retardation film as described in any one of [1] to [7], wherein the aforementioned phase retardation film is a 1 / 4λ phase retardation film. [9] The phase retardation film as described in any one of [1] to [8], wherein when the in-plane direction of the aforementioned phase retardation film exhibiting the maximum refractive index is defined as the X-axis, the in-plane direction of the aforementioned phase retardation film orthogonal to the aforementioned X-axis is defined as the Y-axis, and the thickness direction of the aforementioned phase retardation film is defined as the Z-axis, the refractive index (nx) of the aforementioned X-axis, the refractive index (ny) of the aforementioned Y-axis, and the refractive index (nz) of the aforementioned Z-axis satisfy any one of the following relationships expressed by equations (5) to (7):

[10] The phase retardation film as described in any one of [1] to [9] is a multilayer film comprising a liquid crystal phase retardation layer made of an orthogonally oriented liquid crystal material.

[11] The phase retardation film as described in any one of [1] to

[10] is a multilayer film having a transparent conductive layer on one or both sides.

[12] The phase retardation film as described in

[11] , wherein the aforementioned transparent conductive layer comprises a plurality of metal wires.

[13] The phase retardation film as described in

[12] , wherein the aforementioned metal wires are made of silver, copper, or an alloy comprising at least one of silver and copper.

[14] The phase retardation film as described in any one of

[11] to

[13] , wherein the aforementioned transparent conductive layer comprises at least one of indium tin oxide (ITO), antimony-doped tin oxide (ATO), a conductive polymer, and a carbon-based material.

[15] A method for manufacturing a phase retardation film, which is a method for manufacturing a phase retardation film as described in any one of [1] to

[14] , and comprising: an extension step of extending the film in a direction of 45˚±15˚ relative to the width direction, the film being composed of one or more layers and comprising a composition containing a polyester resin having aryl esters in the side chains.

[16] A method for manufacturing a phase retardation film, which is a method for manufacturing a specific film, the specific film being a multilayer film among the phase retardation films described in any one of [1] to

[14] , and comprising: a step of multilayering the aforementioned multilayer film by any one of co-extrusion molding, coating molding, extrusion lamination molding or lamination; and then an extension step.

[17] A polarizing plate comprising: a phase retardation film as described in any one of [1] to

[14] .

[18] The polarizing plate as described in

[17] , wherein the identification side of the aforementioned phase retardation film further comprises: a 1 / 4λ phase retardation film.

[19] The polarizing plate as described in

[18] , wherein the aforementioned 1 / 4λ phase difference film on the identification side has a surface treatment layer.

[20] The polarizing plate as described in

[19] , wherein the aforementioned surface treatment layer has any one or more of the following effects: hard coating, anti-glare, anti-reflection, low reflection, anti-fouling, and anti-fingerprint.

[21] An image display device comprising: the polarizing plate as described in any one of

[17] to

[20] .

[22] The image display device as described in

[21] , further comprising: a touch detector.

[23] The image display device as described in

[22] , wherein the aforementioned touch detector is an On-Cell type or an In-Cell type.

[24] The image display device as described in

[22] or

[23] , wherein the aforementioned touch detector is a capacitive touch detector having at least one conductive film.

[25] The image display device as described in

[24] , wherein the substrate of the aforementioned conductive film is a polyester resin, a cyclic olefin resin, a polycarbonate resin, or a polyimide resin.

[26] The image display device as described in

[24] or

[25] , wherein the aforementioned conductive film comprises a plurality of metal wires.

[27] The image display device as described in

[26] , wherein the aforementioned metal wires are made of silver, copper, or an alloy comprising at least one of silver and copper.

[28] The image display device as described in any one of

[24] to

[27] , wherein the aforementioned conductive film comprises at least one of indium tin oxide (ITO), antimony-doped tin oxide (ATO), a conductive polymer, and a carbon-based material.

[29] The image display device as described in any one of

[21] to

[28] , which is capable of shape change.

[30] The image display device as described in any one of

[21] to

[29] , which is for use in vehicles.

[31] An information processing apparatus comprising: the image display device described in any one of

[21] to

[30] . [Effect].

[0011] According to the present invention, a phase difference film and a method for manufacturing the same, a polarizing plate having the aforementioned phase difference film, an image display device having the aforementioned polarizing plate, and an information processing device having the aforementioned image display device are provided. The phase difference film has high visibility of phase difference, excellent processing performance, lower cost, and is thin.

[0012] Furthermore, the film formed by casting a composition of a polyester resin containing the aforementioned aryl pyrocycloids in the side chains exhibits a negative phase difference (negative intrinsic refractive index) because the plane of the aryl pyrocycloids in the side chains becomes orthogonal to the main chain after uniaxial extension. This results in a higher refractive index in the direction orthogonal to the extension direction compared to the extension direction. Moreover, since the refractive index difference between the aryl pyrocycloids and the main chain is large, the phase difference manifestation is excellent. Additionally, as another effect, polymers exhibiting negative intrinsic birefringence are generally brittle, but the polyester resin of the present invention has excellent heat resistance and toughness, making it easy to cast and process. Therefore, the phase difference film containing this composition can be appropriately used as a negative A-plate, a positive B-plate, and a positive C-plate, serving as a thin phase difference film capable of effectively compensating for viewing angles.

[0013] Furthermore, the retardation film of the present invention exhibits a positive phase difference, and can also be suitably used as a 1 / 4λ retardation film for a circular polarizer with anti-reflection properties in a wide frequency band by laminating a resin film with a smaller wavelength dispersion than the retardation film of the present invention. Moreover, since the retardation film of the present invention is easy to fabricate, it can be provided at a lower cost than liquid crystal coated 1 / 4λ retardation films.

Implementation Method

[0015] The embodiments of the present invention (hereinafter referred to as "the present embodiments") are described in detail below, but the present invention is not limited thereto and various modifications can be made without departing from its spirit.

[0016] [Phase Retardation Film] The phase retardation film of this embodiment comprises a composition containing a polyester resin with arylated rutiles in its side chains, and the relationship between the in-plane phase retardation Ro(450) and Ro(550) of the aforementioned layer containing the polyester resin is Ro(450) / Ro(550) ≥ 1.22, and the aforementioned layer is extended. We believe that by using a polyester resin with arylated rutiles in its side chains, the orientation direction of the arylated rutile rings is orthogonal to the main chain direction of the polyester resin, thereby making it easier to display phase retardation when the film is extended, and thus exhibiting excellent phase retardation visibility.

[0017] Furthermore, in the polyester resin of this embodiment, due to the influence of the arylated cyclopentadienyl ring, there is a tendency for negative intrinsic birefringence due to a high refractive index in the direction orthogonal to the main chain direction of the polyester resin. Here, the main chain direction of the polyester resin refers to the extension direction when the polymer film is stretched, and the direction orthogonal to this refers to the direction orthogonal to the extension direction.

[0018] As a sample, the in-plane phase difference Ro (450 nm) of the layer containing the polyester resin with aryl ester side chain is preferably 1500 to 8000 nm, more preferably 2000 to 7500 nm, even more preferably 2500 to 7000 nm, and even more preferably 3000 to 6500 nm.

[0019] The in-plane phase difference Ro (550 nm) of the layer containing the polyester resin with aryl ester side chain is preferably 1000-6000 nm, more preferably 1500-5500 nm, even more preferably 2000-5000 nm, and even more preferably 2500-5000 nm.

[0020] The Ro(450 nm) / Ro(550 nm) ratio of the polyester resin layer containing aryl ester side chains is preferably 1.15 to 2.00, more preferably 1.20 to 2.00, even more preferably 1.22 to 2.00, and still more preferably 1.25 to 2.00.

[0021] The phase difference Rth (550 nm) in the thickness direction of the layer containing the polyester resin with aryl ester side chain is preferably -3000 to -500 nm, more preferably -2750 to -750 nm, and even more preferably -2500 to -1000 nm.

[0022] As a sample, the overall Ro (450 nm) of the phase difference film is preferably 55-160 nm, more preferably 70-145 nm, and even more preferably 85-130 nm.

[0023] The overall Ro (550 nm) of the phase difference film is preferably 80-180 nm, preferably 100-165 nm, and even more preferably 120-150 nm.

[0024] The overall Ro(450 nm) / Ro(550 nm) of the phase difference film is preferably 0.50 to 0.90, more preferably 0.55 to 0.92, even more preferably 0.60 to 0.94, and even more preferably 0.65 to 0.96.

[0025] (Polyester resin composition) The polyester resin composition used to constitute the phase retardation film of this embodiment includes the aforementioned predetermined polyester resin, and may include other components commonly used to constitute the phase retardation film, such as other additives described below, as needed.

[0026] (Polyester resin) The polyester resin of this embodiment has aryl esters in its side chains, which can be obtained by, for example, by polymerization of a dicarboxylic acid component having aryl esters with any diol component; polymerization of any dicarboxylic acid component with a diol component having aryl esters; or polymerization of a dicarboxylic acid component having aryl esters with a diol component having aryl esters.

[0027] Furthermore, in this embodiment, "arylation" refers to the introduction of aromatic hydrocarbons and their derivatives via a C-C single bond. The aromatic hydrocarbons may be, for example, polycyclic aromatic hydrocarbon groups such as naphthyl.

[0028] If either the dicarboxylic acid component or the diol component contains at least one compound having an arylate, then one of them may be used alone or in combination with two or more.

[0029] The glass transition temperature of the polyester resin in this embodiment is preferably 90–190°C, more preferably 100–180°C, and even more preferably 110–170°C. With a glass transition temperature of 90°C or higher, the heat resistance of the polyester resin tends to be further improved. Furthermore, with a glass transition temperature of 190°C or lower, the elongation of the polyester resin tends to be further improved. The glass transition temperature can be measured using the method described in the embodiments described later.

[0030] The weight-average molecular weight of the polyester resin in this embodiment is preferably 30,000 to 200,000, more preferably 35,000 to 150,000, and even more preferably 40,000 to 100,000. With a weight-average molecular weight within the above range, the polyester resin tends to have longer molecular chains, resulting in improved mechanical properties such as elongation at break and flexibility, and thus improved elongation. Furthermore, in this embodiment, the weight-average molecular weight can be determined by gel permeation chromatography (GPC) converted to polystyrene. More specifically, it can be determined by the methods described in the examples below.

[0031] The following details the components used to constitute the polyester resin.

[0032] (Dicarboxylic acid component) There is no particular limitation on one type of monomer used to constitute the polyester resin used in this embodiment, i.e., the dicarboxylic acid component. Examples include compounds represented by the following general formula (1). In formula (1), R1a and R1b independently represent phenyl or naphthyl, k independently represents an integer from 0 to 4, and X1 independently represents a C1-8 alkyl group.

[0033] In the above general formula (1), the substitution positions on the rings of the phenyl or naphthyl groups represented by R1a and R1b are not particularly limited. From the perspective of industrial synthesis of monomers, substitution is at the 2-position and / or 7-position. The phase difference manifestation of phenyl is smaller than that of naphthyl, and from the viewpoint of phase difference manifestation, naphthyl is preferred. Naphthyl can be 1-naphthyl or 2-naphthyl, with 2-naphthyl showing greater phase difference manifestation, and is preferred from the viewpoint of phase difference manifestation.

[0034] Polyester resins can be polymerized using a dicarboxylic acid component containing aryl benzoyl groups as monomers, i.e., a mixture of phenyl-substituted derivatives with R1a and R1b being phenyl and naphthyl-substituted derivatives with R1a and R1b being naphthyl. Alternatively, polyester resins polymerized individually can be mixed. Furthermore, a dicarboxylic acid component where one of R1a and R1b is phenyl and the other is naphthyl can be used to polymerize the polyester resin. Both methods are effective for adjusting phase difference visibility.

[0035] The substitution number k of aryl R1a and R1b can be 0, that is, unsubstituted. From the viewpoint of phase difference manifestation, it is preferable that k for both is 1 or more and that the aryl substitution is at both ends of the arene. From this viewpoint, the substitution number k is preferably an integer from 1 to 3, and more preferably 1. Furthermore, in the dicarboxylic acid component having aryl arene, at least one of the two k is 1 or more, and it is preferable that both of the two k are 1.

[0036] The dicarboxylic acid component can be a mixture of unsubstituted dicarboxylic acid components without aryl groups and substituted dicarboxylic acid components with aryl groups, used as raw materials, to polymerize the polyester resin. Alternatively, polyester resins polymerized individually can be mixed. Either method is effective for adjusting the manifestation of phase difference.

[0037] In the above general formula (1), the C1-8 alkyl group represented by X1 can be exemplified as: straight-chain or branched alkyl groups, such as: methylene, ethyl alkyl, trimethylene, propyl alkyl, 2-ethyl ethyl alkyl, 2-methylpropyl-1,3-diyl C1-8 alkyl groups. Among them, the preferred alkyl group is a straight-chain or branched C1-6 alkyl group (e.g.: methylene, ethyl alkyl, trimethylene, propyl alkyl, 2-methylpropyl-1,3-diyl C1-4 alkyl groups).

[0038] The representative compounds represented by the aforementioned general formula (1) are not particularly limited, and examples include: 9,9-bis(2-carboxyethyl) piracetam, 9,9-bis(2-carboxypropyl) piracetam, 9,9-bis(carboxyC4-6 alkyl) piracetam, 9,9-bis(2-carboxyethyl)2,7-diphenyl piracetam, 9,9-bis(2-carboxypropyl)2,7-diphenyl piracetam, 9,9-bis(carboxyC4-6 alkyl)2,7-diphenyl piracetam, 9,9-bis The following are listed: (2-carboxyethyl)2,7-di(2-naphthyl)furan, 9,9-bis(2-carboxypropyl)2,7-di(2-naphthyl)furan, 9,9-bis(carboxyC4-6 alkyl)2,7-di(2-naphthyl)furan, 9,9-bis(2-carboxyethyl)2,7-di(1-naphthyl)furan, 9,9-bis(2-carboxypropyl)2,7-di(1-naphthyl)furan, and 9,9-bis(carboxyC4-6 alkyl)2,7-di(1-naphthyl)furan. Furan dicarboxylic acid components can be alone or in combination of two or more.

[0039] Among them, a preferred dicarboxylic acid component may be, for example, 9,9-bis(2-carboxyethyl)2,7-bis(2-naphthyl)carboxylic acid in the aforementioned general formula (1) in which R1a and R1b are 2-naphthyl and k is 1 and X1 is ethyl. By using such a dicarboxylic acid component, there is a tendency for the phase difference manifestation to be further improved.

[0040] Furthermore, the dicarboxylic acid component is not limited to free carboxylic acids, but also includes: ester-forming derivatives of the aforementioned dicarboxylic acids, such as esters [e.g., alkyl esters [e.g., lower alkyl esters such as methyl esters, ethyl esters (e.g., C1-4 alkyl esters, especially C1-2 alkyl esters)], amide halides (e.g., amide chlorides), and acid anhydrides. Two or more of these dicarboxylic acid components can be used alone or in combination.

[0041] Furthermore, the polyester resin used in this embodiment can be used in combination with the dicarboxylic acid component represented by the above general formula (1) to use a dicarboxylic acid component that does not have a cyclopentadienyl ring.

[0042] The proportion of the dicarboxylic acid component introduced into the polyester resin, represented by the general formula (1) with k being 1 or more, is preferably 80 to 100 mol%, more preferably 90 to 100 mol%, even more preferably 95 to 100 mol%, and particularly preferably 100 mol%. When the proportion of the dicarboxylic acid component represented by the general formula (1) with k being 1 or more, that is, the dicarboxylic acid component having an aryl ring, is within the above range, there is a tendency to exhibit excellent phase difference manifestation.

[0043] (Method for manufacturing dicarboxylic acid component) The following method for manufacturing 9,9-bis(2-methoxycarbonylethyl)2,7-bis(2-naphthyl)furan (DNFDP-m), which is a representative example of an alkyl ester of dicarboxylic acid component represented by the aforementioned general formula (1), will be described.

[0044] The following reaction formula (9) represents one of the synthetic pathways for DNFDP-m. There are multiple synthetic pathways, and it is not limited to this one.

[0045] In the above reaction formula (9), 2,7-dibromofuran is used as the starting material and reacts with 2-naphthoboric acid (Suzuki-Miyaura cross-coupling) to produce 2,7-bis(2-naphthyl)furan (DNF). DNFDP-m is then obtained by the addition reaction of DNF with methyl acrylate (Michael addition).

[0046] The Suzuki-Miyaura cross-coupling in paragraph 1 typically involves reacting a brominated aromatic compound with an aromatic compound containing a borate group using a palladium catalyst in the presence of a base. The base is not particularly limited, but examples include sodium carbonate, potassium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, barium hydroxide, potassium fluoride, potassium phosphate, and potassium acetate. Among these, alkali metal carbonate salts such as potassium carbonate are commonly used. Furthermore, the ratio of base used to 1 mol of 2,7-dibromobenzoic acid is, for example, approximately 0.1 to 50 mol, preferably 1 to 25 mol. Potassium carbonate can be used in the aforementioned reaction.

[0047] The palladium catalyst is not particularly limited, and examples include: tetra(triphenylphosphine)palladium (0), bis(tris(tributylphosphine)phosphine)palladium (0), [1,2-bis(diphenylphosphine)ethane]palladium dichloride (II), [1,3-bis(diphenylphosphine)propane]palladium dichloride (II), [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride (II), bis(triphenylphosphine)palladium dichloride (II), bis(tris(o-toluene)phosphine)palladium dichloride (II), etc. Among these catalysts, tetra(triphenylphosphine)palladium (0) is commonly used. The proportion of the catalyst relative to 1 mol of 2,7-dibromophosphine, converted in metal form, is, for example, about 0.01 to 0.1 mol, preferably 0.03 to 0.07 mol. Tetra(triphenylphosphine)palladium (0) can be used in the aforementioned reaction.

[0048] The coupling reaction can be carried out in the presence of a solvent. Toluene can be used as a solvent in the aforementioned reaction.

[0049] The reaction temperature of the coupling reaction is, for example, 50 to 200°C, preferably 60 to 100°C. In the aforementioned reaction, the reaction temperature is 70 to 80°C.

[0050] After the reaction is complete, the reaction mixture can be separated and purified as needed using conventional separation and purification methods. In the aforementioned reaction, purification can be achieved by crystallization after washing with water.

[0051] The Michael addition reaction in the second stage is a reaction in which the carbon at the 9-position of the methyl acrylate is added to the β-position of the unsaturated carboxylic acid ester in the presence of an alkaline catalyst. After dissolving the DNF obtained in the reaction of the first stage in a solvent, methyl acrylate and the catalyst are added dropwise to the resulting solution, and the reaction is carried out at 50-60°C.

[0052] Alkaline catalysts are not particularly limited as long as they can generate ionization anions, and can use conventional inorganic and organic bases. Examples of inorganic bases include: metal hydroxides (lithium hydroxide, sodium hydroxide, potassium hydroxide, etc.), alkali metal hydroxides; alkaline earth metal hydroxides such as calcium hydroxide and barium hydroxide, etc.

[0053] Examples of organic bases include: metal alkane oxides (alkali metal alkane oxides such as sodium methoxide and sodium ethoxide), quaternary ammonium hydroxides (tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, etc., tetraalkylammonium hydroxide; trimethylbenzylammonium hydroxide, etc.). Furthermore, the aforementioned trimethylbenzylammonium hydroxide can also be obtained from Tokyo Chemical Industry Co., Ltd. under the trade name "TRITON B" (40% methanol solution of trimethylbenzylammonium hydroxide). TRITON B can be used when using DNFDP-m in this embodiment.

[0054] The aforementioned Michael addition reaction can be carried out in the presence of a solvent. The solvent is not particularly limited as long as it is non-reactive to the aforementioned catalyst and can dissolve the compound; it can be used in a wide range of applications. Methyl isobutyl ketone can be used as a solvent when synthesizing DNFDP-m of this embodiment.

[0055] After the reaction is complete, the reaction mixture can be separated and purified as needed using conventional separation and purification methods. In the aforementioned reaction, purification can be achieved by crystallization after washing with water.

[0056] (Diol Component) There is no particular limitation on the type of monomer used to constitute the polyester resin used in this embodiment, i.e., the diol component. Preferably, at least one diol component is selected from the group consisting of diol component (A) represented by general formula (2), diol component (B) represented by general formula (3) and diol component (C) represented by general formula (4). Each diol component is described in detail below.

[0057] (Diol component (A)) One monomer that can constitute the polyester resin used in this embodiment, namely diol component (A), can be represented by the following general formula (2). In formula (2), Z independently represents phenyl or naphthyl, R2a and R2b independently represent substituents that are inert to the reaction, p independently represents an integer from 0 to 4, R3 independently represents alkyl, alkoxy, cycloalkoxy, aryloxy, arylalkoxy, aryl, cycloalkyl, arylalkyl, halogen atom, nitro, or cyano, q independently represents an integer from 0 to 2, R4 independently represents a C2-6 alkyl group, and r independently represents an integer of 1 or more.

[0058] In the aforementioned general formula (2), the radicals R2a and R2b are not particularly limited, and can be, for example, non-reactive substituents such as cyano, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, etc.), and hydrocarbon groups [e.g., alkyl, aryl (phenyl, etc., C6-10 aryl)]. These can be halogen atoms, cyano, or alkyl (especially alkyl). Examples of alkyl groups include: methyl, ethyl, propyl, isopropyl, butyl, tributyl, etc., C1-12 alkyl groups (e.g., C1-8 alkyl groups, especially C1-4 alkyl groups such as methyl). The types of radicals R2a and R2b can be the same or different. The substitution positions of radicals R2a and R2b can be, for example, the 2-position, 7-position, 2-position, and 7-position of the radical. The substitution number p is approximately 0 to 4 (e.g., 0 to 2), preferably 0 or 1, especially 0.

[0059] Furthermore, in this embodiment, the term "inert to the reaction" means that it is inert to the polymerization reaction of the polyester resin.

[0060] In the aforementioned general formula (2), the substituent R3 is not particularly limited, and may be exemplified as: alkyl (e.g., methyl, ethyl, propyl, isopropyl, butyl, tributyl, etc., C1-6 alkyl), cycloalkyl (e.g., cyclohexyl, etc., C5-8 cycloalkyl), aryl (e.g., phenyl, tolyl, xylyl, naphthyl, etc., C6-10 aryl), aralkyl (e.g., benzyl, phenethyl, etc., C6-10 aryl-C1-4 alkyl), hydrocarbon group; alkoxy (e.g., methoxy, ethoxy, etc., C1-6 alkoxy), cycloalkoxy (e.g., cyclohexyloxy, etc., C5-8 cycloalkoxy), aryloxy (e.g., phenoxy, etc., C6-10 aryloxy), arylalkoxy (e.g., benzyloxy, etc., C6-10 aryl-C1-4 alkoxy); halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, iodine atom, etc.); nitro; cyano, etc.

[0061] Preferred R3 can be, for example, alkyl (C1-6 alkyl, preferably C1-4 alkyl, especially methyl), alkoxy (C1-4 alkoxy, etc.), cycloalkyl (C5-8 cycloalkyl), aryl (phenyl, etc., C6-12 aryl), etc.

[0062] The substitution number q can be 0 to 4 (e.g., 0 to 3), and preferably 0 to 2 (e.g., 0 or 1).

[0063] In the aforementioned general formula (2), the C2-6 alkyl group represented by R4 is not particularly limited, and can be, for example, linear or branched C2-6 alkyl groups such as ethyl alkyl, propyl alkyl (1,2-propanediyl), trimethylene, 1,2-butadiyl, and tetramethylene, preferably C2-4 alkyl, and more preferably C2-3 alkyl.

[0064] The number of oxyalkylene groups (OR4) r (addition moles) can be 1 or more, for example: 1 to 12 (e.g., 1 to 8), preferably 1 to 5 (e.g., 1 to 4), even more preferably 1 to 3 (e.g., 1 or 2), especially 1.

[0065] The representative diol component (A) includes: 9,9-bis(hydroxy(poly)alkoxyphenyl) benzoylene, 9,9-bis(hydroxy(poly)alkoxynaphthyl) benzoylene, etc.

[0066] The 9,9-bis(hydroxy(poly)alkoxyphenyl)benzene class includes, for example: (i) 9,9-bis[4-(2-hydroxyethoxy)phenyl]benzene, 9,9-bis[4-(2-hydroxypropoxy)phenyl]benzene, etc.; (ii) 9,9-bis[4-(2-hydroxyethoxy)-3-methylphenyl]benzene, 9,9-bis[4-(2-hydroxyethoxy)-3-methylphenyl]benzene, etc. -3-Isopropylphenyl] , 9,9-bis[4-(2-hydroxyethoxy)-3-isobutylphenyl] , 9,9-bis[4-(2-hydroxyethoxy)-3-tert-butylphenyl] , 9,9-bis[4-(2-hydroxyethoxy)-3,5-dimethylphenyl] , 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butyl-5-methylphenyl) , etc. 9,9-bis(hydroxyC2-4 alkyl) (iii) 9,9-bis(4-(2-hydroxyethoxy)-3-cyclohexylphenyl) and 9,9-bis(hydroxyC2-4alkoxyC5-10cycloalkylphenyl); (iv) 9,9-bis[4-(2-hydroxyethoxy)-3-phenylphenyl], 9,9-bis[4-(2-hydroxypropoxy)-3-phenylphenyl] and 9,9-bis(hydroxyC2-4alkoxyC5-10cycloalkylphenyl) 2,4-alkoxyC6-10 arylphenyl) fu, etc.; compounds in (ii) to (iv) above where r is 2 to 5, such as 9,9-bis(hydroxyC2-4alkoxyC2-4alkoxyphenyl) fu, 9,9-bis(hydroxyC2-4alkoxyC2-4alkoxymono or diC1-4 alkylphenyl) fu, 9,9-bis(hydroxyC2-4alkoxyC2-4alkoxyC6-10 arylphenyl) fu, etc.

[0067] 9,9-bis(hydroxy(poly)alkoxynaphthyl) fucose compounds include, for example: 9,9-bis(hydroxyalkoxynaphthyl) fucose [e.g., 9,9-bis[6-(2-hydroxyethoxy)-2-naphthyl] fucose, 9,9-bis[5-(2-hydroxyethoxy)-1-naphthyl] fucose, 9,9-bis[6-(2-hydroxypropoxy)-2-naphthyl] fucose, etc., 9,9-bis(hydroxyC2-4alkoxynaphthyl) fucose, etc.]; compounds with r being 2 to 5, such as 9,9-bis(hydroxyC2-4alkoxyC2-4alkoxynaphthyl) fucose, etc.

[0068] These diol components (A) can be used alone or in combination of two or more. A particularly preferred diol component (A) is, for example, 9,9-bis[4-(2-hydroxyethoxy)phenyl] benzoxate in the aforementioned general formula (2) in which Z is phenyl and p and q are 0 and R4 is ethyl and r is 1.

[0069] Although the specific composition may vary depending on the type and proportion of the dicarboxylic acid used, generally speaking, the proportion of diol component (A) used relative to the overall diol component is preferably 0-80 mol%, more preferably 0-50 mol%, and even more preferably 0-20 mol%. When the proportion of diol component (A) is 0 mol% or higher, there is a tendency to further increase the glass transition temperature. Furthermore, when the proportion of diol component (A) is 80 mol% or lower, there is a tendency to further improve film formability, reduce the photoelasticity coefficient, and improve phase difference visibility.

[0070] (Diol component (B)) One monomer that can constitute the polyester resin used in this embodiment, namely diol component (B), can be represented by the following general formula (3). In formula (3), R5a and R5b each independently represent substituents that are inert to the reaction, m each independently represent an integer from 0 to 4, and X2 each independently represent a C1-8 alkyl group.

[0071] In the aforementioned general formula (3), the bases R5a and R5b, m include the preferred state sample and are the same as the bases R2a and R2b, p described in the aforementioned general formula (2). In addition, X2 includes the preferred state sample and is the same as X1 described in the aforementioned general formula (1).

[0072] Representative compounds represented by the aforementioned general formula (3) include, for example, 9,9-bis(hydroxymethyl)furan, 9,9-bis(hydroxyethyl)furan, 9,9-bis(hydroxyC3-6 alkyl)furan, etc. Two or more of these diol components (B) may be used alone or in combination. A preferred diol component (B) is, for example, 9,9-bis(hydroxymethyl)furan.

[0073] Although the proportion may vary depending on the type and ratio of the dicarboxylic acid component used, as a general rule, the proportion of the diol component (B) used relative to the overall diol component is preferably 0-80 mol%, more preferably 0-50 mol%, and even more preferably 0-20 mol%. By keeping the proportion of the diol component (B) within the above range, there is a tendency for a greater manifestation of negative phase difference.

[0074] (Diol component (C)) One of the monomers that can constitute the polyester resin used in this embodiment, namely the diol component (C), can be represented by the following general formula (4). In formula (4), X3 represents a C2-8 alkyl group.

[0075] The diol component (C) is not particularly limited, but may include: linear or branched alkyldiols (ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, neopentanediol, 1,6-hexanediol, etc., C2-8 alkyldiols, preferably C2-6 alkyldiols, more preferably C2-4 alkyldiols), polyalkyldiols (e.g., diethylene glycol, dipropylene glycol, triethylene glycol, etc., di or triC2-4 alkyldiols, etc.). Two or more diol components (C) may be used alone or in combination.

[0076] Preferably, the diol component (C) is ethylene glycol in which X3 is an ethyl group in the aforementioned general formula (4). By using such a diol component (C), there is a tendency for the elongation to be further improved.

[0077] Although it may vary depending on the type and proportion of the dicarboxylic acid component used, as a general rule, the proportion of the diol component (C) used relative to the overall diol component can be selected from, for example, about 10 mol% or more (e.g., 30 to 100 mol%), and can be, for example, about 50 mol% or more (e.g., 60 to 99 mol%), more preferably 70 mol% or more (e.g., 80 to 98 mol%), more preferably about 90 mol% or more (e.g., 95 to 97 mol%), and in particular, it can be 100%, that is, the diol component is actually composed only of the diol component (C).

[0078] In addition, as other samples, the proportion of the diol component (C) used relative to the overall diol component is preferably 5 to 50 mol%, preferably 5 to 35 mol%, and even more preferably 15 to 25 mol%.

[0079] Although it may vary depending on the type and proportion of dicarboxylic acid components used, by using diol components (C) in proportions as described above, there is a tendency to further improve the flexibility of the phase difference film.

[0080] (Other Additives) The phase difference film of this embodiment can be supplemented with various additives as needed. Examples of additives include: plasticizers, flame retardants, stabilizers, antistatic agents, fillers, foaming agents, defoamers, lubricants, release agents, slip-adhesive agents, etc.

[0081] Examples of plasticizers include esters, phthalic acid compounds, epoxy compounds, sulfonamides, etc., and examples of flame retardants include inorganic flame retardants, organic flame retardants, colloidal flame retardants, etc.

[0082] Stabilizers can be, for example, antioxidants, ultraviolet absorbers, heat stabilizers, etc., and fillers can be, for example, oxide-based inorganic fillers, non-oxide-based inorganic fillers, metal powders, etc.

[0083] Examples of mold release agents include: natural waxes, synthetic waxes, straight-chain fatty acids or their metal salts, amides, etc.

[0084] Examples of slip-resistant additives include inorganic microparticles such as silicon dioxide, titanium dioxide, calcium carbonate, clay, mica, and kaolin; and organic microparticles such as (meth)acrylic resins and styrene resins (crosslinked polystyrene resins, etc.). These additives may be used alone or in combination of two or more.

[0085] The proportion of these additives relative to 100 parts by weight of polyester resin is, for example, 30 parts by weight or less, preferably 0.1 to 20 parts by weight, and more preferably 1 to 10 parts by weight.

[0086] (Manufacturing Method of Polyester Resin) The aforementioned polyester resin can be prepared by reacting a dicarboxylic acid component with a diol component. There are no particular limitations on the manufacturing method of the polyester resin; conventional methods can be used, such as: transesterification, direct polymerization, melt polymerization, solution polymerization, interfacial polymerization, etc. In the polymerization reaction, transesterification catalysts, condensation catalysts, heat stabilizers, light stabilizers, polymerization modifiers, etc., can be used.

[0087] The transesterification catalyst is not particularly limited, and examples include compounds of alkaline earth metals (magnesium, calcium, barium, etc.) and transition metals (manganese, zinc, cobalt, titanium, etc.) (alkoxides, organic acid salts, inorganic acid salts, metal oxides, etc.). Among them, manganese acetate and calcium acetate can be used appropriately.

[0088] There is no particular limitation on the type of condensation catalyst. Examples include: compounds of alkaline earth metals, transition metals, Group 13 metals (such as aluminum), Group 14 elements (such as germanium), and Group 15 metals (such as antimony). More specifically, examples include: germanium compounds such as germanium dioxide, germanium hydroxide, germanium oxalate, germanium tetraethoxide, and germanium n-butoxide; antimony compounds such as antimony trioxide, antimony acetate, and antimony glycol; and titanium compounds such as tetra-n-propyl titanate, tetra-isopropyl titanate, tetra-n-butyl titanate, and titanium oxalate. These catalysts can be used alone or in combination of two or more.

[0089] The heat stabilizer is not particularly limited, but may include, for example, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, phosphorous acid, trimethyl phosphite, triethyl phosphite and other phosphorus compounds.

[0090] In the reaction, the ratio of dicarboxylic acid component to diol component can be selected from the same range as described above, and an excess of a predetermined component can be used as needed. For example, diol components such as ethylene glycol that can be distilled from the reaction system can be used in excess of the proportion of units introduced into the polyester resin. Furthermore, the reaction can be carried out in the presence or absence of a solvent.

[0091] The reaction can be carried out in an inert gas environment (nitrogen, helium, etc.). Furthermore, the reaction can also be carried out under reduced pressure (e.g., around 1×10² to 1×10⁴ Pa). The reaction temperature can be adjusted according to the polymerization method; for example, in melt polymerization, the reaction temperature can be 150–300°C, preferably 180–290°C, and more preferably around 200–280°C.

[0092] A composition containing a polyester resin with the aforementioned aryl esters in its side chains can be configured as a polymeric compound, comprising: a polyester resin with aryl esters in its side chains and a polycarbonate resin. The composition of the polycarbonate resin is not particularly limited as long as it is miscible with the aforementioned polyester resin; for example, bisphenol A and an aromatic polycarbonate resin with an ester structure, or an alicyclic polycarbonate resin with an isosorbide structure, can be used. Furthermore, a polymeric compound can be configured to further include other resins besides the polyester resin with the aforementioned aryl esters in its side chains and the aforementioned polycarbonate resin, depending on the need. In this way, by configuring the polyester resin as a polymeric compound, optical properties such as phase difference visibility can be appropriately controlled.

[0093] In the aforementioned polymer compound, the ratio of polyester resin to polycarbonate resin is only required to ensure that the polyester resin and polycarbonate resin are miscible, and there is no particular limitation. For example, the preferred ratio of polyester resin relative to the total amount of polyester resin and polycarbonate resin is: 30% by weight or more, 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, or substantially 100% by weight.

[0094] The method for preparing the aforementioned polymer compound is not particularly limited and can be any conventional method, such as: dissolving the two resin components in a solvent, or using a kneading machine (or extruder, such as a biaxial extruder, etc.) to melt-mix them. From the viewpoint of preventing the reduction of optical properties (low birefringence, high transparency, etc.) due to residual solvent after film formation, the melt-mixing method is preferred.

[0095] (Types of Phase Retardation Thin Films) Phase retardation thin films are classified according to the inherent birefringence of their materials and their stretching methods as follows: positive A-plate, negative A-plate, positive B-plate, negative B-plate, positive C-plate, negative C-plate, etc. These plates can be combined for various applications in display devices. Materials with negative inherent birefringence can be uniaxially stretched to form negative A-plates and positive B-plates, and can be biaxially stretched to form positive C-plates.

[0096] A negative A-type plate is defined as a plate in which the refractive index of the phase difference film is in-plane and the direction with the maximum refractive index is defined as the X-axis, the direction orthogonal to the X-axis is defined as the Y-axis, and the thickness direction is defined as the Z-axis, such that the refractive index of the X-axis (nx), the refractive index of the Y-axis (ny), and the refractive index of the Z-axis (nz) satisfy the relationship expressed by the following equation (5). A negative A-type plate is used, for example, in organic EL display devices to suppress the contrast reduction caused by external light reflection.

[0097] A positive B-plate refers to a plate that satisfies the relationship expressed by the following formula (6). A positive B-plate is used, for example, in a liquid crystal display device equipped with an in-plane switching (IPS) liquid crystal cell to perform optical compensation to prevent contrast reduction and color distortion caused by viewing angle.

[0098] A positive C-plate refers to a plate that satisfies the relationship expressed by the following formula (7). A positive C-plate is used, for example, to adjust the phase difference value (Rth) in the thickness direction while maintaining the in-plane phase difference value (Ro) adjusted by the phase difference film.

[0099] The “nx = ny” in the positive C-plate of Equation (6) can refer not only to the case where the in-plane refractive index (nx) and refractive index (ny) are strictly equal, but also to the case where nx and ny are substantially equal. In the statement “nz = nx” in Equation (5), the in-plane refractive index (nx or ny) and the refractive index (nz) in the thickness direction do not necessarily have to be completely consistent. On the other hand, when the Nz coefficient is defined as (nx - nz) / (nx - ny), if the Nz coefficient is greater than -0.1 but less than 0.1, it can be regarded as a negative A-plate with nx = nz. In addition, if the Nz coefficient is less than -10, it can be regarded as a positive C-plate with nx = ny.

[0100] The extended phase retardation film of this embodiment can be used in conjunction with a liquid crystal phase retardation layer composed of an oriented liquid crystal material. The orientation direction of the liquid crystal material is not particularly limited. For example, oriented it in a horizontal (homogeneous) direction relative to the film surface, Ro can be appropriately controlled, and oriented it in a vertical (homeotropic) direction relative to the film surface, Rth can be appropriately controlled.

[0101] The aforementioned liquid crystal material can be any material known in the field of phase retardation thin films, and can be a material whose orientation is fixed by polymerizing or crosslinking a polymerizable liquid crystal compound. Fixing the orientation means that a stable liquid crystal phase retardation layer can be established, and its optical properties will not change due to temperature changes, etc.

[0102] The orientation method of the liquid crystal material can be any method known in the field of phase difference thin films, and there are no particular limitations. Methods such as friction treatment, stretching treatment, magnetic field orientation treatment, electric field orientation treatment, tilting evaporation method, and photo-orientation treatment can be used.

[0103] The phase retardation film of this embodiment can be a 1 / 4λ phase retardation film, which has the function of converting linearly polarized light into circularly polarized light, or vice versa. A 1 / 4λ phase retardation film refers to a phase retardation film that displays an in-plane phase difference Ro(λ) = λ / 4 (or an odd multiple thereof) at a predetermined wavelength λ nm. The phase retardation film of this embodiment can be configured as a 1 / 4λ phase retardation film for specific applications by controlling not only the chemical structure but also the stretching conditions such as stretching temperature and stretching speed, or the film thickness obtained after stretching.

[0104] The 1 / 4λ retardation film is also laminated with a polarizer to serve as a circular polarizer. The circular polarizer is used on the recognition side of an organic EL display device to suppress contrast reduction caused by external light reflection. The organic EL display device includes a circular polarizer and an organic EL panel, which is composed of organic EL elements. The organic EL display device is arranged in the following order from the recognition side: polarizer, retardation film, metal electrodes of the organic EL panel, etc.

[0105] Explanation of the relationship between light incident from the identification side and the display device. External light incident from the identification side is linearly polarized by a polarizer that allows only light polarized in a specific direction to pass through, and then converted to circularly polarized light by a phase retardation film. The circularly polarized incident light reaches the metal electrodes of the organic EL panel and is reflected by these electrodes. This reflection converts the incident light into reflected light with its circular polarization state reversed. The reflected light, with its circular polarization state reversed, then passes through the phase retardation film again and is converted into linearly polarized light that is 90° more inclined than when incident. This 90° inclined linearly polarized reflected light reaches the polarizer that allows only 0° light to pass through and is absorbed, thus blocking penetration to the identification side. Through this series of steps, even if external light incident from the identification side is reflected by the metal electrodes of the organic EL panel, it cannot penetrate to the identification side. Through this action, the display device can maintain a high contrast on the recognition side without reflecting external light.

[0106] External light incident from the identification side is generally assumed to have any wavelength in the visible light region λ = 400 to 780 nm. The phase difference film can perform higher precision optical compensation by controlling the predetermined phase difference over the entire visible light region. For example, in a 1 / 4λ phase difference film, the phase difference of the phase difference film is ideally λ / 4 (nm) in the entire visible light region.

[0107] Here, wavelength dispersion refers to the relationship between wavelength and phase difference. The characteristic that the absolute value of the phase difference increases with increasing wavelength is called inverse wavelength dispersion. For example, if the phase difference is λ / 4 (nm) in the entire visible light region, then the phase difference film will have inverse wavelength dispersion in the entire visible light region. λ / 4 phase difference films with this inverse wavelength dispersion are sometimes difficult to construct using only existing monomeric polymer materials. Instead, they can be designed by extending multilayer films, which are composed of polymeric monomers with positive intrinsic birefringence and polymeric monomers with negative intrinsic birefringence.

[0108] The retardation film of this embodiment can be a single-layer retardation film or a retardation film composed of multiple layers, as long as at least one layer contains the aforementioned polyester resin. In particular, for retardation films used in organic EL displays, it is preferable to provide a multilayer film composed of polyester resin and other resins. In this way, although it is a multilayer film, it can be provided as a retardation film that is thinner and has better reverse wavelength dispersion than conventional retardation films.

[0109] In particular, when the phase retardation film is composed of multiple layers, as shown in Figure 1, it is preferable to use a multilayer film (phase retardation film 10), which includes: a layer 11 containing the aforementioned polyester resin, and a resin layer 12 having positive inherent birefringence. Figure 1 is a schematic cross-sectional view illustrating a 1 / 4λ phase retardation film of this embodiment. Such a multilayer film, i.e., a 1 / 4λ phase retardation film, can be a thin film with a total thickness thinner than a phase retardation film subjected to conventional orientation treatment, and the wavelength dispersion of the phase retardation exhibits inverse dispersion. Such a phase retardation film can be laminated with a polarizing plate to give it viewing angle compensation function.

[0110] Furthermore, although Figure 1 illustrates a phase retardation film comprising one polyester resin layer 11 and one resin layer 12 having positive inherent birefringence, the phase retardation film 10 composed of multiple layers may also be a multilayer phase retardation film with three or more layers, further including other layers not shown in Figure 1. Alternatively, it may be a multilayer phase retardation film with three or more layers, each comprising two or more polyester resin layers 11 and resin layers 12 having positive inherent birefringence.

[0111] When the aforementioned phase retardation film is deposited on a substrate film to produce a laminated film, the substrate film itself can also be a phase retardation film and used as a support. Examples of such laminated films include: viewing angle compensation films for IPS modes obtained by laminating a substrate film with a negative B-type plate, and 1 / 4λ phase retardation films for OLED circular polarizers obtained by laminating a substrate film with a positive A-type plate. At this time, the substrate film material is preferably a resin with positive intrinsic birefringence. Various polymers are equivalent to this resin, such as: polycarbonate resins, polyamide resins, polyvinyl alcohol resins, cellulose ester resins such as cellulose triacetate film and cellulose acetate propionate film, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyarylate resins, polyimide resins, cycloolefin resins, polyurethane resins, polyether urethane resins, and polyolefin resins such as polyethylene and polypropylene. Among these, polycarbonate resins or polyamide resins are particularly preferred due to their excellent elongation, with polyamide resins being even more preferred. Because polycarbonate resins have excellent film-forming properties and excellent adhesion to the aforementioned phase difference films, and polyamide resins have excellent chemical resistance, a wide range of solvents can be used when coating layers containing polyester resins.

[0112] Furthermore, when the substrate film is peeled off and transferred (laminated) onto other films for use, there are no particular limitations on the optical properties of the substrate film, as long as it is a film with good peelability. Such a substrate film is not particularly limited, and can be any of the following conventional materials: polyethylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polyethylene film, polypropylene film, cellophane, cellulose diacetate film, cellulose triacetate film, cellulose acetate butyrate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polybutene film, polymethylpentene film, polyurethane film, polyetheretherketone film, polyetherurethane film, polyetherimide film, polyimide film, fluoropolymer film, and nylon film. Among these, polyethylene terephthalate and cellulose triacetate films are preferred.

[0113] When the original film (film before stretching) of the phase difference film of this embodiment is manufactured into a single layer film of the aforementioned polyester resin, the film-forming method (or film-forming step) is not particularly limited, and examples include: molding method (or solution molding method, solution flow casting method), extrusion method (inflation method, T-die method, etc. melt extrusion method), curtain method, etc. From the viewpoint that it not only has excellent productivity but also can prevent the reduction of optical properties caused by residual solvent, melt extrusion method such as T-die method is preferred.

[0114] When the aforementioned original film is manufactured into a laminated film comprising the aforementioned polyester resin layer and a substrate, the film-making method may include, for example, co-extrusion molding, coating molding, extrusion lamination molding, lamination, etc.

[0115] The co-extrusion molding method is, for example, the resin of the substrate and the aforementioned polyester resin are individually melted and extruded using an extruder, and then combined using a feed block, and co-extruded using a T die to form a film.

[0116] The coating forming method involves coating a solution containing the aforementioned polyester resin onto a substrate film and evaporating the solvent by drying to form a layer containing the aforementioned polyester resin.

[0117] The extrusion lamination method is to form a multilayer film by using cooling rollers and pressure rollers to clamp the aforementioned polyester resin and substrate film, which have been melted and extruded into a film on a substrate film.

[0118] The lamination method involves separately forming a layer containing the aforementioned polyester resin and a substrate using any method, and then using a pressure roller to clamp these layers together to form a multilayer film. At this time, the pressure roller can be heated to improve the adhesion between the layers.

[0119] From the viewpoint of manufacturing efficiency and preventing volatile components such as solvents from remaining in the film, co-extrusion molding is preferred. However, due to interfacial adhesion, the types of resins that can be used in co-extrusion molding are sometimes limited. From the viewpoints of limiting resin degradation, film thickness uniformity, and foreign matter removal, coating molding is preferred. However, due to the solubility of the resin, the types of solvents that can be used in coating molding are sometimes limited.

[0120] When manufacturing the aforementioned laminated film, an adhesive layer for improving adhesion may be provided between the layer containing the aforementioned polyester resin and the substrate.

[0121] The material of the aforementioned adhesive layer is not particularly limited as long as it contains the aforementioned polyester resin layer and has good adhesion to the substrate. Examples include: polycarbonate resin, polyamide resin, polyvinyl alcohol resin, cellulose ester resin such as cellulose triacetate film and cellulose acetate propionate film, polyester resin such as polyethylene terephthalate and polyethylene naphthalate, polyaramid resin, polyimide resin, cycloolefin resin, polyurethane resin, polyether resin, polystyrene and polypropylene, etc.

[0122] There is no particular limitation on the method for making a laminated film consisting of three layers including the aforementioned polyester resin layer, the aforementioned adhesive layer, and the substrate. For example, a laminated film consisting of two adjacent layers can be made by methods such as co-extrusion molding, coating molding, and extrusion lamination molding, and then a third layer can be formed in another step. Alternatively, to improve productivity, the three layers can be made simultaneously by methods such as co-extrusion molding.

[0123] One type of co-extrusion molding method, namely the co-extrusion T-die method, includes, for example, a feed block method and a multi-branch method. From the viewpoint of reducing the variation in the thickness of each layer, the multi-branch method is particularly preferred. When using co-extrusion molding to manufacture laminated films, the melting temperature of the extruded resin is preferably above Tg+80°C, preferably above Tg+100°C, preferably below Tg+180°C, and preferably below Tg+150°C. The aforementioned melting temperature, for example, refers to the melting temperature of the resin in an extruder equipped with a T-die in the co-extrusion T-die method. When the melting temperature of the extruded resin is above the lower limit of the aforementioned range, the resin fluidity can be sufficiently improved, resulting in good formability, and when it is below the upper limit, resin deterioration can be suppressed.

[0124] Co-extrusion molding typically involves sealing the thin film of molten resin extruded from a sliding die against a cooling roller and cooling it to harden it. Methods for sealing the molten resin against the cooling roller include, for example, air knife method, vacuum box method, and electrostatic sealing method.

[0125] In the coating forming method, in order to improve the adhesion between the aforementioned polyester resin and the substrate film, the following surface treatments may be performed: surface roughening treatment by sandblasting and solvent treatment, or surface oxidation treatment such as corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment, electron beam irradiation treatment, etc.

[0126] In the coating forming method, the solvents for the aforementioned polyester resin can be, for example: aromatic solvents such as benzene, toluene, and xylene; ketone solvents such as diacetone alcohol, acetone, cyclohexanone, cyclopentanone, methyl ethyl ketone, and methyl isopropyl ketone; cycloalkane solvents such as cyclohexane, ethylcyclohexane, and 1,2-dimethylcyclohexane; halogen-containing solvents such as dichloromethane and chloroform; and ether solvents such as tetrahydrofuran and dioxane. From the viewpoint of obtaining a suitable viscosity for coating, the concentration of resin in the coating solution can be from 1% to 50% by weight. One solvent can be used alone, or two or more solvents can be used in any proportion.

[0127] There is no limitation on the coating method of the coating liquid. Examples of coating methods include: curtain coating, extrusion coating, roller coating, spin coating, dip coating, bar coating, spray coating, glide coating, printing coating, gravure coating, mold coating, slot coating, and immersion coating, etc.

[0128] There is no limitation on the drying method of the coating liquid. For example, drying by heating or drying under reduced pressure can be used.

[0129] (Extension method of phase difference film) The phase difference film of this embodiment preferably has an extension step of extending the film in a direction of 45˚±15˚ relative to the width direction, the film having a first resin layer containing a polyester resin with aryl esters in the side chain.

[0130] Circular polarizers formed by laminating a polarizer and a phase difference film are often designed so that the direction in which the polarizer absorbs light is tilted relative to the direction in which the phase difference film causes a phase difference in the light. This polarizer is often manufactured with its long side having the direction of light absorption. When the direction in which the phase difference film causes a phase difference in the light is the long side or parallel to the direction of absorption, the phase difference film must be cut in the tilted direction when laminating the polarizer and the phase difference film.

[0131] However, if the phase retardation film is cut in an inclined direction, a large number of phase retardation film ends will be generated, which will become a significant loss during mass production.

[0132] Therefore, the retardation film used as part of the circular polarizer is extended in a direction of 45˚±15˚ relative to the width direction, so that the retardation is manifested in this direction, which can greatly reduce the end loss in the lamination step with the polarizer. In this way, since the retardation film extending in the inclined direction can also be produced in a long continuous manner, the productivity is greatly improved.

[0133] In particular, the phase retardation film of this embodiment is cheaper than the phase retardation film with the liquid crystal layer because it has high visibility of phase retardation and is thin. It can also be continuously produced by tilting and stretching, which can further reduce the manufacturing cost compared with liquid crystals that require multiple steps.

[0134] Furthermore, the phase difference film of this embodiment can be configured as a negative A-plate and a positive B-plate by uniaxial stretching. Uniaxial stretching can be either fixed-end uniaxial stretching or free-end uniaxial stretching. From the viewpoint of less necking and easier adjustment of physical properties, fixed-end uniaxial stretching is preferred. The stretching direction can be any of the following: longitudinal stretching relative to the long side of the film, transverse stretching towards the width direction, or inclined stretching towards an oblique direction (e.g., at an angle of 45˚ relative to the long side). The stretching direction is not particularly limited and can be conventional methods such as inter-roll stretching, heated roll stretching, compression stretching, or stretching.

[0135] When uniaxial stretching is performed, the stretching temperature will vary depending on the desired phase difference, and may be, for example, (Tg-10)~(Tg+20)℃, preferably (Tg-5)~(Tg+10)℃, more preferably (Tg-3)~(Tg+5)℃ (e.g., (Tg+2)~(Tg+5)℃). Specific temperatures may be, for example, 100~150℃, preferably 110~145℃, more preferably 120~140℃ (e.g., 129~133℃). If the stretching temperature is within the aforementioned range, not only is the desired phase difference more easily manifested, but the film can also be stretched more uniformly, thereby better suppressing breakage.

[0136] When it is uniaxially extended, the elongation ratio will vary depending on the desired phase difference, and may be, for example, 1.1 to 5 times, preferably 1.3 to 3.5 times, and more preferably about 1.5 to 2.5 times. If the elongation ratio is above the lower limit of the above, it is easier to obtain the desired phase difference. If the elongation ratio is below the upper limit of the above, it is possible to further suppress the increase of phase difference or film breakage. The phase difference film of this embodiment has good elongation and toughness, so the film is not easy to break, and because of the high phase difference manifestation, the desired phase difference can still be obtained even if it is a film.

[0137] When it is a single-axis extension, the extension speed can be, for example, 1 to 100 mm / min, preferably 20 to 80 mm / min, and more preferably about 50 to 70 mm / min. If the extension speed is above the lower limit of the above, it is easier to obtain the desired phase difference.

[0138] The phase difference film of this embodiment can be configured as a positive C-plate by biaxial stretching. Biaxial stretching can be either sequential biaxial stretching or simultaneous biaxial stretching. Sequential biaxial stretching typically involves longitudinal stretching by inter-roll stretching followed by transverse stretching by stretching. Inter-roll stretching has disadvantages such as necking and scratch transfer caused by contact with the rolls. Simultaneous biaxial stretching has disadvantages such as necking between clamps at both ends of the film, but simultaneous biaxial stretching is preferred in order to make the in-plane phase difference almost zero.

[0139] When biaxial stretching is performed, the stretching temperature can be, for example, (Tg-10) to (Tg+20) °C, preferably (Tg-5) to (Tg+10) °C, and even more preferably (Tg-3) to (Tg+5) °C (e.g., (Tg+2) to (Tg+5) °C). Specifically, the temperature can be, for example, 100 to 150 °C, preferably 110 to 145 °C, and even more preferably 120 to 140 °C (e.g., 129 to 133 °C). If the stretching temperature is within the aforementioned range, not only is it easier to exhibit the desired phase difference, but the film can also be stretched more uniformly, thereby further suppressing breakage.

[0140] When biaxially extended, the elongation ratio will vary depending on the desired phase difference. To achieve a zero in-plane phase difference, it is advisable to set the elongation ratio to be equal in both the longitudinal and transverse directions. The elongation ratio can be, for example, 1.1 to 5 × 1.1 to 5 times, preferably 1.3 to 3.5 × 1.3 to 3.5 times, and even more preferably around 1.5 to 2.5 × 1.5 to 2.5 times. If the elongation ratio is above the lower limit mentioned above, the desired phase difference is easily obtained. If the elongation ratio is below the upper limit mentioned above, the increase in phase difference or film breakage can be more effectively suppressed. The phase difference film of this embodiment has good elongation and toughness, so the film is not easily broken, and because of its high phase difference visibility, the desired phase difference can still be obtained even as a thin film.

[0141] When biaxial stretching is performed, the stretching speed should preferably be equal in both the longitudinal and transverse directions to achieve a phase difference of 0. The stretching speed can be, for example, 1–100 mm / min, preferably 20–80 mm / min, and more preferably around 50–70 mm / min. When the stretching speed is above the lower limit mentioned above, the resulting film tends to have a larger phase difference. Furthermore, when the stretching speed is below the upper limit mentioned above, there is a tendency to further suppress film breakage. The phase difference film of this embodiment has good stretchability and toughness, so the film is not easily broken, and because of its high phase difference visibility, the desired phase difference can still be obtained even when it is a thin film.

[0142] Furthermore, other films (or coatings) can be deposited on the phase retardation film as needed, as long as the effect of the present invention is not impaired. For example, surfactants, release agents, and polymer layers containing microparticles can be coated on the surface of the phase retardation film to form a slip-resistant layer.

[0143] The polyester resin-containing film (or resin layer) of this embodiment can be formed into a film, and even when thinned, it still exhibits a large phase difference. Therefore, the thickness of the film or resin layer before stretching can be selected from, for example, a range of about 3 to 20 μm (e.g., 5 to 10 μm). The thickness of the stretched phase difference film (or polyester resin-containing layer) can be, for example, about 1 to 10 μm (e.g., 2 to 8 μm), preferably 1.5 to 8 μm (e.g., 3 to 5 μm), and more preferably about 2.0 to 5 μm (e.g., 2.5 to 3.5 μm).

[0144] Furthermore, the total thickness of the extended single-layer or multi-layer retardation film is preferably 1 to 50 μm, more preferably 5 to 40 μm, and even more preferably 10 to 35 μm. By using the polyester resin of this embodiment, a retardation film that has been further thinned in this way can be achieved.

[0145] The phase retardation film of this embodiment has negative intrinsic birefringence and high phase retardation visibility. Therefore, by changing the stretching method, negative phase retardation films (negative A-plate, positive B-plate, positive C-plate) can be fabricated. Such phase retardation films can be appropriately used for viewing angle compensation plates in liquid crystal displays and for viewing angle compensation of circular polarizers in organic EL displays.

[0146] The phase retardation film of this embodiment can be configured as a conductive phase retardation film by forming a transparent conductive layer on one or both sides of it. As a conductive phase retardation film, it can not only perform the functions of a phase retardation film, but also have the functions of electrodes for electronic components such as touch panels, and electromagnetic wave shielding functions to block electromagnetic waves that cause malfunctions in electronic devices.

[0147] The aforementioned transparent conductive layer only needs to have high conductivity and high transparency, and there are no particular limitations. For example, it can be formed with a plurality of metal wires.

[0148] The aforementioned metal wires are preferably made of silver, copper, or an alloy containing at least one of these materials because of their excellent conductivity. By using such metal materials with excellent conductivity, even if the wire width is reduced to improve transparency, sufficient conductivity can still be maintained.

[0149] The aforementioned method for forming metal nanowires is not particularly limited, and can be, for example, a method of forming by exposing a layer composed of a photosensitive material such as silver halide into a pattern and then performing a development process; a method of forming by etching a conductive layer formed by evaporation, sputtering or lamination of metal foil into a pattern; a method of forming by printing metal ink containing metal nanowires by inkjet printing or screen printing, etc.

[0150] The line width of the aforementioned metal wire is not particularly limited. From the viewpoint that it exhibits high conductivity and is not easily identifiable, 1 to 20 µm is preferred, 1 to 10 µm is more preferred, and 1 to 5 µm is even more preferred.

[0151] In addition to the aforementioned metal wires, the aforementioned transparent conductive layer may also include: indium tin oxide (ITO), antimony-doped tin oxide (ATO), a conductive polymer, or a carbon-based material. Using these materials, a transparent conductive layer can be formed that maintains sufficient conductivity even after thinning to the thickness required to achieve transparency. Indium tin oxide is preferred due to its high conductivity and transparency. This transparent conductive layer can be formed into a thin film using methods such as vapor deposition and sputtering, and can be further patterned as needed after film formation.

[0152] [Polarizing Plate] Next, the polarizing plate of this embodiment will be described with reference to Figures 2A and 2B. This polarizing plate includes the aforementioned phase difference film. Figures 2A and 2B are schematic cross-sectional views illustrating one aspect of the polarizing plate.

[0153] The polarizing plate 20 shown in Figure 2A has the following layers stacked in sequence: a phase retardation film 10, a polarizer 22, and a polarizer protective film 24. As shown in the figure, an adhesive layer 21 can be provided between the phase retardation film 10 and the polarizer 22, and an adhesive layer 23 can also be provided between the polarizer 22 and the polarizer protective film 24.

[0154] The polarizing plate 30 shown in Figure 2B has the following layers stacked in sequence: a phase retardation film 10, a polarizing film protective film 32, a polarizing film 34, and a polarizing film protective film 36. An adhesive layer 31 may be provided between the phase retardation film 10 and the polarizing film protective film 32, and adhesive layers 33 and 35 may also be provided between the polarizing film 34 and the polarizing film protective films 32 and 36.

[0155] The polarizer protective film 10 may be supplied with the following treatments to improve the adhesion between it and the polarizer 22: corona treatment and plasma treatment, and surface modification treatment by a strongly alkaline aqueous solution such as sodium hydroxide and potassium hydroxide. The formation of these adhesive layers and the surface modification treatment may be performed after the film-forming step or after the stretching step.

[0156] The polarizer 22 is not particularly limited as long as it is a known material. Examples include: a product obtained by dyeing and stretching a hydrophilic polymer film using iodine and dichroic dyes or other dichroic substances, such as a polyvinyl alcohol film, a partially formaldehyde-modified polyvinyl alcohol film, or a partially saponified ethylene-vinyl acetate copolymer film; or polyolefin-based oriented films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride. Furthermore, examples include: a polarizer obtained by dyeing a polyvinyl alcohol film with iodine and then uniaxially stretching it.

[0157] The polarizer protective film 24 is not particularly limited as long as it is a material with high adhesion to the polarizer 22 and optical transparency. Examples include: cellulose triacetate film, cellulose acetate propionate film and other cellulose ester films, modified acrylic resin films, ultra-high birefringence polyethylene terephthalate resin films, cycloolefin films, etc.

[0158] Furthermore, the polarizing plate of this embodiment may further include a 1 / 4λ phase retardation film on the identification side of the aforementioned phase retardation film. With such a configuration, in which a 1 / 4λ phase retardation film is further deposited on the phase retardation film of this embodiment, light from the backlight (hereinafter referred to as the "light-emitting side") of the organic EL display device or liquid crystal display device can be circularly polarized.

[0159] For example: Generally, a polarizing plate is provided on the recognition side of a display device to make the light linearly polarized. When the person wearing sunglasses is in the same direction as the polarizing plate, sometimes a problem of not being able to recognize the light, also known as blackout, occurs. To avoid this problem, after the light from the light-emitting side is linearly polarized by the polarizing plate, it passes through the aforementioned 1 / 4λ phase difference film with circular polarization function. The light recognized by the person is then circularly polarized, thus preventing blackout. This function is also called sunglasses readability.

[0160] The 1 / 4λ phase difference film deposited on the recognition side of the phase difference film is not only intended to enable the incident light and reflected light to be circularly polarized so as to enable the polarizing plate to absorb the reflected light in the organic EL display device as described above, but also intended to enable the light from the light emission side to be circularly polarized so as to avoid blackout.

[0161] As described above, since the 1 / 4λ phase difference film has multiple different functions, in order to avoid confusion, the one that aims to make the incident light and reflected light circularly polarized in order to make the polarizing plate absorb the reflected light in the organic EL display device is called "the first type of 1 / 4λ phase difference film", and the one that aims to make the light from the light-emitting side circularly polarized and avoid blackout is called "the second type of 1 / 4λ phase difference film".

[0162] On the surface of the aforementioned second type of 1 / 4λ phase difference film, a surface treatment layer described later may be formed as needed.

[0163] The aforementioned surface treatment layer is used to improve the function of the polarizing plate of this embodiment. Specifically, it can be a layer that has one or more of the following effects: hard coating, anti-glare, anti-reflection, low reflection, anti-fouling or anti-fingerprint.

[0164] The aforementioned layer with a hard coating effect can be made of conventional materials without particular limitation. A resin compound that polymerizes and / or reacts due to heat, chemical reaction, or irradiation by an electron beam, radiation, or ultraviolet light can be suitable. Examples of such curing resins include (meth)acrylic, epoxy, melamine, silicone, and polyvinyl alcohol curing resins. From the viewpoint of obtaining high surface hardness or optical properties, (meth)acrylic curing resins that cure due to electron beams or ultraviolet light are preferred. Furthermore, the step of providing a hard coating on the second type of 1 / 4λ phase difference film in this embodiment can be performed before or after the aforementioned extension.

[0165] The aforementioned anti-glare layer is not particularly limited. Representative layers may include: layers with uneven surfaces to diffuse incident light from the outside and suppress glare and reflection. Methods for forming uneven surfaces include, for example: methods that directly roughen the surface by sandblasting and embossing; and methods that contain inorganic fillers (microparticles such as silicon oxide) and organic fillers (microparticles such as polystyrene resin and acrylic resin) with a diameter of about a few μm in a curing resin and then cure it to create uneven surfaces derived from the aforementioned inorganic or organic fillers.

[0166] The aforementioned anti-reflective layer is not particularly limited. Representative layers may include: a layer in which multiple layers of dielectric thin films (anti-reflective films) composed of inorganic materials are coated to cause the reflected light generated at the interface of each film to interfere with the reflected light generated at the outermost surface, thereby suppressing the reflection of external light.

[0167] The aforementioned layer with low reflectivity is not particularly limited, and a layer that reduces the refractive index of the outermost surface to suppress external light reflection can be used. Methods for reducing the refractive index of the outermost surface include, for example, coating with a resin containing a low-refractive-index material such as fluorine-based materials; and forming a structure on the surface that is finer than the wavelength of visible light, thereby substantially setting the refractive index of the surface to the average refractive index of air in the fine structure, and thus reducing the refractive index.

[0168] The aforementioned layer with anti-fouling and anti-fingerprint effects is not particularly limited, and can be formed by dry coating or wet coating of a material with excellent water-repellent or oil-repellent properties. Specific examples of the aforementioned material with excellent water-repellent or oil-repellent properties include, for example, silicone compounds and fluorine compounds.

[0169] [Image Display Device] Next, the image display device of this embodiment will be described with reference to Figures 3A and 3B. The image display device of this embodiment is not particularly limited as long as it possesses the aforementioned polarizing plate; examples include organic electroluminescent (EL) display devices and liquid crystal display devices. Furthermore, the image display device is not limited to devices that are marketed as finished products in standalone form; it can also be part of information processing devices, such as smartphones, described later. Figure 3A is a schematic cross-sectional view illustrating one aspect of an organic EL display device of this embodiment, and Figure 3B is a schematic cross-sectional view illustrating one aspect of a liquid crystal display device of this embodiment.

[0170] As shown in Figure 3A, the organic EL display device 40 sequentially includes: an organic EL display panel 41, a polarizing plate 20 having the phase retardation film 10 of this embodiment, and a front panel 43. In the organic EL display device 40, by using the polarizing plate 20 having the 1 / 4λ phase retardation film, external light reflection is suppressed, and a black with less coloring is displayed.

[0171] Furthermore, the OLED display device 40 may be equipped with other components such as a touch detector 42 as needed. By equipping the touch detector 42, the OLED display device 40 can not only perform the functions of a display device, but also the functions of an information input interface. The layers used to constitute the OLED display device 40 can be bonded together separately using an adhesive.

[0172] As shown in Figure 3B, the liquid crystal display device 50 sequentially includes: a light source 51, a polarizing plate 30, a liquid crystal panel 52, and a front panel 53. The light source 51 can be a direct-lit type with the light sources evenly distributed directly below the liquid crystal panel, or it can be a side-lit type with a reflector and a light guide plate. Furthermore, although the front panel 53 is shown in Figure 3B, the liquid crystal display device 50 may not have a front panel 53. The liquid crystal display device 50 may further include a touch detector (not shown).

[0173] The aforementioned touch detector can be configured as an In-Cell type touch detector, which is disposed inside the OLED display panel 41 and the liquid crystal panel 52, or it can be configured as an On-Cell type touch detector, which is disposed between the OLED display panel 41 and the polarizing plate 20, and between the liquid crystal panel 52 and the polarizing plate 30. Using In-Cell or On-Cell type touch detectors can reduce thickness and weight compared to conventional external touch detectors.

[0174] The aforementioned touch detector is not particularly limited in its method, and can use any of the previously known capacitive, optical, ultrasonic, electromagnetic induction, or resistive film methods. Among these, a capacitive touch detector with at least one conductive film is preferred because it can detect multiple touch positions simultaneously and has excellent durability.

[0175] The aforementioned conductive film can be a film formed by forming a conductive layer on the surface of a substrate film. The aforementioned substrate film is not particularly limited as long as it can form the aforementioned conductive layer. Due to its high processability, it is preferred to use any one of polyester resin, cyclic olefin resin, polycarbonate resin or polyimide resin.

[0176] The conductive layer formed on the aforementioned conductive film is only required to have high conductivity and high transparency, and there are no particular limitations. For example, it may be formed with a plurality of metal wires.

[0177] The aforementioned metal wires are preferably made of silver, copper, or an alloy containing at least one of these materials because of their excellent conductivity. By using such metal materials with excellent conductivity, even if the wire width is reduced to improve transparency, sufficient conductivity can still be maintained.

[0178] The aforementioned method for forming metal nanowires is not particularly limited, and can be, for example, a method of forming by exposing a layer composed of a photosensitive material such as silver halide into a pattern and then performing a development process; a method of forming by etching a conductive layer formed by evaporation, sputtering or lamination of metal foil into a pattern; a method of forming by printing metal ink containing metal nanowires by inkjet printing or screen printing, etc.

[0179] The line width of the aforementioned metal wire is not particularly limited. From the viewpoint that it exhibits high conductivity and is not easy to identify, 1 to 20 µm is preferred, 1 to 10 µm is more preferred, and 1 to 5 µm is even better.

[0180] In addition to the aforementioned metal wires, the conductive layer formed on the aforementioned conductive thin film may also include: indium tin oxide (ITO), antimony-doped tin oxide (ATO), a conductive polymer, or a carbon-based material. Using these materials, a transparent conductive layer can be formed that maintains sufficient conductivity even after thinning to the thickness at which transparency becomes apparent. Indium tin oxide is preferred due to its high conductivity and transparency. This transparent conductive layer can be formed into a thin film using methods such as vapor deposition and sputtering, and can be further patterned as needed after film formation.

[0181] Furthermore, the screen of the image display device is not limited to a quadrilateral, but can have a circular, elliptical, or polygonal shape such as a triangle or pentagon. Moreover, the image display device can be flexible, changing its shape by warping, bending, rolling, or folding. For example, as shown in Figure 4, the image display device includes a roll-up display that allows the image display device 61, which is housed in a roller shape within the image display device housing 62, to be pulled out for use.

[0182] The image display device of this embodiment has minimal changes in optical properties such as coloring in high-temperature environments, and can therefore be appropriately used as an in-vehicle image display device such as a car navigation device, a rear-view monitor, or a head-up display.

[0183] [Information Processing Apparatus] Next, the information processing apparatus of this embodiment will be described with reference to FIG. 5. This FIG. is a perspective view schematically showing the information processing apparatus 60 of this embodiment. The information processing apparatus 60 includes the image display device having the aforementioned polarizing plate. The information processing apparatus 60 is a smartphone having an image processing apparatus 61. The image processing apparatus 61 can be configured, for example, as the aforementioned organic EL display device 40 or liquid crystal display device 50.

[0184] Such an information processing device 60 is not particularly limited to smartphones, and can include various devices capable of information processing such as personal computers and tablet terminals. The thinness of the polarizing plate of this embodiment can be particularly utilized in personal computers, smartphones, tablet terminals, etc., where thinness and miniaturization are desired. Furthermore, the reverse wavelength dispersion of the polarizing plate of this embodiment can be further utilized in personal computers, smartphones, tablet terminals, etc., used in various locations such as indoors and outdoors.

[0185] Furthermore, the information processing device 60 may also include, for example, a foldable smartphone (Figure 6) that has a bendable image display device 61 and is foldable, or a rollable smartphone (Figure 7) that can pull out the image display device 61 that is housed in a roller shape.

[0186] Furthermore, the image display device 61 described above may have the function of generating an input / output interface for an information processing device, and may also have the function of generating an output interface for outputting various processing results of the information processing device and an input interface such as a touch panel for operating the information processing device. Other components of the information processing device are not particularly limited; typical examples may include: a processor, a communication interface for controlling wired or wireless communication, an input / output interface other than the image display device, memory, a storage device, and one or more communication buses for interconnecting these components. [Example]

[0187] The present invention will be described in more detail below with reference to embodiments, but the present invention is not limited to these embodiments. The evaluation method and raw materials are as follows.

[0188] [Evaluation Method] (Glass Transition Temperature (Tg)) Using a differential scanning calorimeter (Seiko Instruments Co., Ltd. "DSC 6220"), the sample was placed in an aluminum weighing pan, and Tg was measured in the range of 30℃ to 200℃ according to JIS K 7121.

[0189] (Molecular weight) The sample was dissolved in chloroform and the weight average molecular weight Mw was determined by using a gel permeation chromatography system (manufactured by TOSOH Corporation, "HLC-8120GPC").

[0190] (Ro, Rth, birefringence characteristics) Using a hysteresis measuring device (RETS-100 manufactured by Otsuka Electronics Co., Ltd.), the Ro (450), Ro (550), Rth (550), nx, ny, and nz of the stretched film were measured at a measuring temperature of 20°C.

[0191] The so-called birefringence property "nx = ny" not only includes the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. For example, if the coefficient Nz in the following formula is less than -10, it can be regarded as a positive C-plate with nx = ny.

[0192] Furthermore, in the statement "nx = nz", the in-plane refractive index (nx or ny) and the refractive index nz in the thickness direction do not necessarily have to be exactly the same. For example, if the Nz coefficient in the following formula is greater than -0.1 but less than 0.1, it can be regarded as a negative A-type plate with nx = nz. Unless otherwise specified, the Nz coefficient is the value expressed as (nx - nz) / (nx - ny).

[0193] (Average thickness) Using a thickness gauge (Mitutoyo Co., Ltd. "micrometer"), measure 3 points at equal intervals between the clamps along the long side of the film, and calculate its average value.

[0194] [Raw Materials] (Synthesis Example 1: FDPm: 9,9-bis(2-methoxycarbonylethyl)furan [dimethyl ester of 9,9-bis(2-carboxyethyl)furan (or furan-9,9-dipropionic acid)]) 200 mL of 1,4-dioxane and 33.2 g (0.2 mol) of furan were added to a reactor and stirred until dissolved. Then, 3.0 mL of a 40% by weight methanol solution of trimethylbenzyl ammonium hydroxide (manufactured by Tokyo Chemical Industry Co., Ltd., "TRITON B40") was added dropwise while the mixture was cooled to 10°C, and the mixture was stirred for 30 minutes. Next, 37.9 g (0.44 mol) of methyl acrylate was added, and the mixture was stirred for approximately 3 hours. After the reaction was complete, 200 mL of toluene and 50 mL of 0.5 N hydrochloric acid were added for washing. After removing the aqueous layer, the organic layer was washed three times with 30 mL of distilled water. The solvent was distilled off to obtain 84.0 g of 9,9-bis(methyl propionate)[9,9-bis{2-(methoxycarbonyl)ethyl} ...methoxycarbonyl)ethyl}[9,9-bis{2-methoxycarbonyl)ethyl}[9,9-bis{2-methoxycarbonyl][9,9-bis{2-methoxycarbonyl][9,9-bis{2-methoxycarbonyl][9,9-bis{2-methoxycarbonyl][9,9-bis{2-(methoxycarbonyl)ethyl}[9,9-bis{2-(methoxycarbonyl)ethyl}[9,9-bis{2-(methoxycarbonyl)ethyl}[9,

[0195] (Synthetic Example 2: DNFDP-m: 9,9-bis(2-methoxycarbonylethyl)2,7-di(2-naphthyl)bufenozide) 192.3 g (0.39 mol) of 2,7-dibromobufenozide, 200 g (1.2 mol) of 2-naphthenic acid, 4.3 L of dimethoxyethane, and 1 L of 2 M sodium carbonate aqueous solution were fed into a reactor. Under a nitrogen atmosphere, 22.4 g (19.4 mmol) of tetra(triphenylphosphine)palladium(O) [or Pd(PPh3)4] was added, and the mixture was heated under reflux at an internal temperature of 71–78 °C for 5 hours to allow the reaction to proceed. After cooling to room temperature, 2.0 L of toluene and 500 mL of deionized water were added, and the mixture was washed five times by liquid-liquid extraction. The organic layer changed from a deep orange to brown. The insoluble matter was filtered and concentrated to obtain 305 g of brown crude crystals. The crude crystals were dissolved by heating in a mixture of 1.5 kg ethyl acetate and 300 g isopropanol (IPA), then cooled with ice water to below 10°C and stirred for 1 hour to allow crystals to precipitate. The precipitated crystals were filtered and dried under reduced pressure to obtain 130 g of grayish-brown crystals. The grayish-brown crystals were purified using column chromatography (silicone support, developing solvent: chloroform:ethyl acetate (v / v) = 4:1), recrystallized with methanol, and dried under reduced pressure to obtain 116 g of 9,9-bis(2-methoxycarbonylethyl)2,7-di(2-naphthyl)enazine (DNFDP-m) (white crystals, yield 54.9%, HPLC purity 99.4% by area).

[0196] In the following description, the abbreviations refer to the following substances respectively. BPEF: 9,9-bis[4-(2-hydroxyethoxy)phenyl]pyroxene, manufactured by Osaka Gas Chemicals Co., Ltd. EG: Ethylene glycol. PA: Polyamide, TROGAMID CX7323, manufactured by Daicel Evonik Co., Ltd. PC: Polycarbonate, Iupilon E-2000, manufactured by Mitsubishi Engineering-Plastics Co., Ltd.

[0197] [Manufacturing Example 1] 0.65 mol of DNFDP-m, 0.7 mol of BPEF, 0.35 mol of FDP-m, and 2.30 mol of EG were mixed with 2 × 10⁻⁴ mol of manganese acetate tetrahydrate and 8 × 10⁻⁴ mol of calcium acetate monohydrate as transesterification catalysts. The mixture was slowly heated to melt while stirring. After heating to 230°C, 14 × 10⁻⁴ mol of trimethyl phosphate and 20 × 10⁻⁴ mol of germanium oxide were added. The mixture was then slowly heated and depressurized until it reached 270°C and below 0.13 kPa, while removing EG. After reaching the predetermined stirring torque, the contents were removed from the reactor to prepare polyester resin granules.

[0198] Analysis of the obtained particles by 1H-NMR revealed that 65 mol% of the dicarboxylic acid component introduced into the polyester resin originated from DNFDP-m and 35% from FDP-m, while 70 mol% of the introduced diol component originated from BPEF and 30 mol% from EG. The glass transition temperature (Tg) of the obtained polyester resin was 132°C, and the weight-average molecular weight (Mw) was 90,000. This resin is referred to as Resin A.

[0199] [Manufacturing Example 2] Except that the raw materials were set as DNFDP-m 1.00 mol, BPEF 0.80 mol, and EG 2.20 mol, the polyester resin was prepared in the same manner as in Manufacturing Example 1. Analysis of the obtained particles by 1H-NMR showed that 100 mol% of the dicarboxylic acid component introduced into the polyester resin originated from DNFDP-m, 80 mol% of the diol component originated from BPEF, and 20 mol% originated from EG. The resulting polyester resin had a glass transition temperature (Tg) of 162°C and a weight-average molecular weight (Mw) of 90,000. This resin is referred to as Resin B.

[0200] [Manufacturing Example 3] Except for setting the raw materials as DNFDP-m 0.50 mol, BPEF 0.80 mol, FDPm 0.50 mol, and EG 2.20 mol, the polyester resin was prepared in the same manner as in Manufacturing Example 1. Analysis of the obtained particles by 1H-NMR showed that 50 mol% of the dicarboxylic acid component introduced into the polyester resin originated from DNFDP-m, 50 mol% from FDPm, and 80 mol% of the diol component originated from BPEF and 20 mol% from EG. The resulting polyester resin had a glass transition temperature (Tg) of 142°C and a weight-average molecular weight (Mw) of 90,000. This resin is referred to as Resin C.

[0201] [Manufacturing Example 4] Except that the raw materials were set as follows: 0.75 mol DNFDP-m, 0.2 mol BPEF, 0.25 mol FDPm, and 2.80 mol EG, the polyester resin was prepared using the same method as in Manufacturing Example 1. Analysis of the obtained particles by 1H-NMR showed that 75 mol% of the dicarboxylic acid component introduced into the polyester resin originated from DNFDP-m, and 25 mol% originated from FDPm; 20 mol% of the diol component introduced into the resin originated from BPEF, and 80 mol% originated from EG. The resulting polyester resin had a glass transition temperature (Tg) of 127°C and a weight-average molecular weight (Mw) of 90,000. This resin is referred to as Resin D.

[0202] [Manufacturing Example 5] Except that the raw materials were set as FDPm 1.00 mol, BPEF 0.80 mol, and EG 2.20 mol, the polyester resin was prepared in the same manner as in Manufacturing Example 1. The resulting polyester resin had a glass transition temperature Tg of 126°C and a weight average molecular weight Mw of 43,600. This resin is referred to as Resin E.

[0203] [Examples 1-6, Comparative Example 1] After drying about 1 g of each resin particle obtained in Manufacturing Examples 1-5 above, they were sandwiched between two spacers with a length of 12 cm, a width of 12 cm, and a thickness of 0.1 mm, which were covered with polyimide film. A vacuum heating and pressurizing device (Igen Manufacturing Co., Ltd. "11FD type") was used to pressurize them at a temperature 20°C to 40°C higher than the glass transition temperature Tg of the resin at a pressure of 5 MPa for 10 minutes. Then each spacer was removed and cooled to produce an unstretched film.

[0204] Various unstretched films were subjected to free-end uniaxial stretching using a stretching apparatus under the stretching conditions described in Table 1. The physical properties of the resulting stretched films were measured, and the results are shown in Table 1.

[0205] [Examples 7-10, Comparative Examples 2-3] The resin particles obtained in Manufacturing Examples 1-2, 4, and 5 were dissolved in tetrahydrofuran at a concentration of 30%, and then coated onto PA or PC films using a spreader and dried at 80°C for 8 hours to produce unstretched laminated films as shown in Table 2.

[0206] These various unstretched films were subjected to uniaxial stretching at either the free end or the fixed end using a stretching apparatus under the stretching conditions described in Table 2. Various physical properties of the resulting stretched films were measured, and the results are shown in Table 2.

[0207] [Table 1]

[0208] [Table 2]

[0209] As can be clearly seen from Table 1, it can be confirmed that the polyester resin of the present invention has a very high phase difference value and wavelength dispersion compared with conventional polyester resins with cycloids in the side chains. In addition, it has been shown that the phase difference Rth in the thickness direction of any material becomes a negative value, and these are materials that can be used as negative A plates, positive B plates and positive C plates for viewing angle compensation in display devices.

[0210] As is clearly seen from Table 2, by laminating a layer containing the polyester resin of the present invention with a film having a positive phase difference, a phase difference film can be created, the wavelength dispersion of which exhibits inverse dispersion. It can be confirmed that such phase difference films can further thin the 1 / 4λ phase difference film, which has undergone orientation treatment by previously known stretching techniques. [Industrial Applicability]

[0211] The phase difference film of the present invention has a negative phase difference Rth in the thickness direction, thus enabling sufficient phase difference to be obtained from a thin film. It is also non-brittle and easy to process, making it suitable as a negative A-plate, positive B-plate, and positive C-plate. Furthermore, by being a thin film laminated with a resin having positive inherent birefringence, it can also be configured as a 1 / 4λ phase difference film, exhibiting inverse dispersion in the wavelength dispersion of the phase difference. Laminating such a phase difference film with a polarizing plate enables it to have viewing angle compensation functionality, making it suitable for use in image display devices equipped with the aforementioned polarizing plate (e.g., reflective liquid crystal display devices, transmissive liquid crystal display devices, organic EL display devices, etc.). [Simplified Explanation of the Diagram]

[0014] Figure 1 is a schematic cross-sectional view illustrating a 1 / 4λ phase difference film according to an embodiment of the present invention. Figure 2A is a schematic cross-sectional view illustrating a polarizing plate according to an embodiment of the present invention. Figure 2B is a schematic cross-sectional view illustrating a polarizing plate according to another embodiment of the present invention. Figure 3A is a schematic cross-sectional view illustrating an image display device (OLED (Organic Light Emitting Diode)) according to an embodiment of the present invention. Figure 3B is a schematic cross-sectional view illustrating an image display device (LCD) according to an embodiment of the present invention. Figure 4 is a schematic cross-sectional view illustrating a rollable display according to an embodiment of the present invention. Figure 5 is a schematic perspective view illustrating an information processing device according to an embodiment of the present invention. Figure 6 is a schematic perspective view illustrating a foldable smartphone according to an embodiment of the present invention. Figure 7 is a schematic perspective view illustrating a rollable smartphone according to an embodiment of the present invention. [Biomaterial Storage]

[0213] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. A phase difference film comprising one or more layers, wherein at least one of the layers comprises a composition of a polyester resin having aryl esters in the side chains, and the in-plane phase difference Ro(450) and Ro(550) of the aforementioned layer comprising the aforementioned polyester resin are related by Ro(450) / Ro(550) ≥ 1.22, and the aforementioned layer is extended.

2. The phase retardation film as claimed in claim 1, wherein, The aforementioned components exhibit negative intrinsic birefringence.

3. The phase retardation film as described in claim 1 or 2, wherein, The aforementioned polyester resin contains a specific polyester resin comprising the following components as monomers: a dicarboxylic acid component represented by the following general formula (1), and at least one diol component selected from the group consisting of diol component (A) represented by the following general formula (2), diol component (B) represented by the following general formula (3) and diol component (C) represented by the following general formula (4), and k is 1 or more in at least a portion or all of the dicarboxylic acid component represented by the following general formula (1); In formula (1), R1a and R1b independently represent phenyl or naphthyl, k independently represents an integer from 0 to 4, and X1 independently represents a C1-8 alkyl group; In formula (2), Z independently represents phenyl or naphthyl, R2a and R2b independently represent inert substituents, p independently represents integers from 0 to 4, R3 independently represents alkyl, alkoxy, cycloalkoxy, aryloxy, arylalkoxy, aryl, cycloalkyl, arylalkyl, halogen atom, nitro, or cyano, q independently represents integers from 0 to 2, R4 independently represents C2-6 alkyl, and r independently represents integers greater than 1; In formula (3), R5a and R5b independently represent inert substituents, m independently represents integers from 0 to 4, and X2 independently represents C1-8 alkyl; In formula (4), X3 represents C2-8 alkyl.

4. The phase retardation film as claimed in claim 3, wherein, The aforementioned polyester resin includes a specific polyester resin comprising the following components as monomers: a dicarboxylic acid component in which R1a and R1b are 2-naphthyl and k is 1 and X1 is ethyl in the aforementioned general formula (1), and at least one diol component selected from the group consisting of a diol component (A) in which Z is phenyl and p and q are 0 and R4 is ethyl and r is 1 and a diol component (C) in which X3 is ethyl in the aforementioned general formula (4).

5. The phase retardation film as claimed in claim 1, wherein, The composition of the aforementioned polyester resin containing the aforementioned aryl esters in the side chain is a polymer compound, which comprises: the aforementioned polyester resin containing the aforementioned aryl esters in the side chain, and a polycarbonate resin.

6. The phase retardation film as claimed in claim 1, wherein, The aforementioned phase difference film is a multilayer film, which includes: a layer containing the aforementioned polyester resin, and a resin layer having positive inherent birefringence.

7. The phase retardation film as claimed in claim 6, wherein, The aforementioned resin layer with positive inherent birefringence comprises a polyamide resin.

8. The phase retardation thin film as claimed in claim 1, wherein, The aforementioned phase difference film is a 1 / 4λ phase difference film.

9. The phase retardation thin film as claimed in claim 1, wherein, When the direction in-plane of the aforementioned phase difference film that exhibits the maximum refractive index is defined as the X-axis, the direction in-plane of the aforementioned phase difference film that is orthogonal to the aforementioned X-axis is defined as the Y-axis, and the thickness direction of the aforementioned phase difference film is defined as the Z-axis, the refractive index (nx) of the aforementioned X-axis, the refractive index (ny) of the aforementioned Y-axis, and the refractive index (nz) of the aforementioned Z-axis satisfy any one of the following relationships expressed by equations (5) to (7):

10. The phase retardation film as claimed in claim 1, which is a multilayer film comprising a liquid crystal phase retardation layer made of oriented liquid crystal material.

11. The phase difference film as claimed in claim 1, which is a multilayer film having a transparent conductive layer on one or both sides.

12. The phase retardation thin film as claimed in claim 11, wherein, The aforementioned transparent conductive layer comprises a plurality of fine metal wires.

13. The phase retardation thin film as claimed in claim 12, wherein, The aforementioned metal wire is made of silver, copper, or an alloy containing at least one of silver and copper.

14. The phase retardation film as claimed in any one of claims 11 to 13, wherein, The aforementioned transparent conductive layer comprises at least one of indium tin oxide (ITO), antimony-doped tin oxide (ATO), conductive polymer, and carbon-based material.

15. A method for manufacturing a phase retardation film, which is a method for manufacturing a phase retardation film according to any one of claims 1 to 14, and comprising: an extension step of extending the film in a direction of 45˚±15˚ relative to the width direction, the film being composed of one or more layers and comprising a composition of a polyester resin having aryl compounds as side chains.

16. A method for manufacturing a phase retardation thin film, which is a method for manufacturing a specific thin film, the specific thin film being a multilayer thin film among the phase retardation thin films according to any one of claims 1 to 14, and comprising: a step of forming the aforementioned multilayer thin film by any one of co-extrusion molding, coating molding, extrusion lamination molding or lamination; and then a step of stretching.

17. A polarizing plate comprising: a phase difference film as described in any one of claims 1 to 14.

18. The polarizing plate as claimed in claim 17, wherein the identification side of the aforementioned phase retardation film further comprises: a 1 / 4λ phase retardation film.

19. The polarizing plate as claimed in claim 18, wherein the aforementioned 1 / 4λ phase difference film on the identification side has a surface treatment layer.

20. The polarizing plate as claimed in claim 19, wherein, The aforementioned surface treatment layer has one or more of the following effects: hard coating, anti-glare, anti-reflection, low reflection, anti-fouling, and anti-fingerprint.

21. An image display device comprising: a polarizing plate as described in any one of claims 17 to 20.

22. The image display device as claimed in claim 21, further comprising: a touch detector.

23. The image display apparatus as claimed in claim 22, wherein, The aforementioned touch detector is either an On-Cell or In-Cell type.

24. The image display apparatus as claimed in claim 22 or 23, wherein, The aforementioned touch detector is a capacitive touch detector having at least one conductive thin film.

25. The image display apparatus as claimed in claim 24, wherein, The substrate of the aforementioned conductive film is polyester resin, cyclic olefin resin, polycarbonate resin, or polyimide resin.

26. The image display apparatus as claimed in claim 24, wherein, The aforementioned conductive film comprises a plurality of fine metal wires.

27. The image display apparatus as claimed in claim 26, wherein, The aforementioned metal wire is made of silver, copper, or an alloy containing at least one of silver and copper.

28. The image display apparatus as claimed in claim 24, wherein, The aforementioned conductive thin film includes at least one of indium tin oxide (ITO), antimony-doped tin oxide (ATO), conductive polymers, and carbon-based materials.

29. The image display device as claimed in claim 21, which is capable of changing shape.

30. The image display device as claimed in claim 21, which is for vehicle use.

31. An information processing apparatus comprising: an image display device as described in any one of claims 21 to 30.

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