Polarizing film, optical laminate, and organic el display device

Abstract

Provided are a polarizing film in which dyeing unevenness can be suppressed and excellent optical durability is obtained, an optical laminate, and an organic EL display device. A polarizing film according to an embodiment of the present invention comprises a polyvinyl alcohol resin and an organic dye. The thickness of the polarizing film is 10 µm or less. The single-layer transmittance of the polarizing film is 45% or more. The degree of polarization of the polarizing film is 95% or less. The organic dye includes a first dye that is an azo compound having a ureide skeleton represented by formula (1) or a salt thereof.

Description

Polarizing film, optical laminate, and organic EL display device

[0001] This invention relates to polarizing films, optical laminates, and organic EL display devices.

[0002] Conventionally, polarizing films have been applied to various industrial products to impart appropriate optical compensation performance to them. For example, a thin, high-performance polarizing film has been proposed that contains iodine, a dichroic substance, and a polyvinyl alcohol-based resin, has a single-component transmittance of 42.0% or more, and a polarization degree of 99.95% or more (see, for example, Patent Document 1). To manufacture such a thin, high-performance polarizing film, first, a polyvinyl alcohol-based resin layer is formed on a resin substrate. Next, a laminate comprising the resin substrate and the polyvinyl alcohol-based resin layer is immersed in a boric acid aqueous solution to insolubilize the polyvinyl alcohol-based resin layer. Then, the polyvinyl alcohol-based resin layer is stained with iodine, and the laminate is stretched in a boric acid aqueous solution. This forms a thin, high-performance polarizing film on the resin substrate.

[0003] International Publication No. 2010 / 100917

[0004] In recent years, the development of industrial products to which polarizing films are applied has progressed, and the polarization characteristics required of polarizing films have become more diverse. For example, in the case of a polarizing film, if the single-layer transmittance is 45% or more, even if the degree of polarization is 95% or less, it may be possible to provide sufficient optical compensation performance to industrial products. However, in the manufacturing method of a thin, high-performance polarizing film described in Patent Document 1, if the dyeing process is adjusted so that the single-layer transmittance of the thin, high-performance polarizing film is 45% or more, it becomes difficult to dye the thin, high-performance polarizing film uniformly, and streaky dyeing irregularities may occur in the thin, high-performance polarizing film. Furthermore, thin, high-performance polarizing films with a single-layer transmittance of 45% or more have the problem that when exposed to high temperature and / or high humidity environments, decolorization (color loss) occurs, and the polarization characteristics deteriorate significantly. The present invention has been made to solve the above conventional problems, and its main objective is to provide a polarizing film, an optical laminate, and an organic EL display device that can suppress dyeing irregularities and have excellent optical durability.

[0005] [1] The polarizing film according to an embodiment of the present invention contains a polyvinyl alcohol-based resin and an organic dye. The thickness of the polarizing film is 10 μm or less. The single transmittance of the polarizing film is 45% or more. The degree of polarization of the polarizing film is 95% or less. The organic dye contains a first dye which is an azo compound having a ureido skeleton represented by the following formula (1) or a salt thereof. In formula (1), Ay １ and Ay ２ are each independently a naphthyl group which may have a substituent or a phenyl group which may have a substituent, s and t are each independently 0 or 1, and either s or t is 1, Ry １ to Ry ８ each independently represent a hydrogen atom or a substituent: The phenyl group which may have a substituent is a phenyl group having at least one or more substituents selected from the group consisting of a sulfo group, a carboxy group, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a nitro group, an amino group, an alkyl-substituted amino group having 1 to 4 carbon atoms, and an alkyl-substituted acylamino group having 1 to 4 carbon atoms, and the naphthyl group which may have a substituent is a naphthyl group which may have a substituent selected from the group consisting of a hydroxy group, an alkoxy group having 1 to 4 carbon atoms having a sulfo group, and a sulfo group: Ry １ , Ry ２ , Ry ７ , Ry [[ID=1'7]] ８ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to '4 carbon atoms, and Ry ３ to Ry ６ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms having a sulfo group. [2] In the polarizing film described in [1] above, the organic dye may further contain a second dye which is an azo compound represented by the following formula (2) or a salt thereof and a third dye which is an azo compound represented by the following formula (3) or a salt thereof. In formula (2), Ar １１ represents a phenyl group having a substituent or a naphthyl group having a substituent, and Rr １１ to Rr １６Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group, and Xr １１ represents an amino group which may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a benzoyl group which may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a phenylamino group which may have substituents selected from the group consisting of C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a benzoylamino group which may have substituents selected from the group consisting of C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a phenylazo group which may have substituents selected from the group consisting of C1-C4 alkoxy groups, sulfo groups, hydroxyl groups, amino groups, and substituted amino groups; or a naphthotriazole group which may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups, and m1 and n1 each independently represent 0 or 1, and when m1 and n1 are 1, Rr １５ and Rr １６ Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group, and when m1 and n1 are 0, Rr １１ and Rr １２ Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group having a sulfo group. In equation (3), A is Ar in equation (2). １１ Similarly, or the following general formula (4) (In formula (4), A １ R is a substituent represented by (where represents a nitro group or an amino group), １ ~R ４ , R ６ Rr in the above formula (2) １１ ~Rr １４ Similarly, X is Xr of equation (2) above. １１The same applies, where m and n are 0 or 1, respectively. [3] In the polarizing film described in [2] above, the content of the first dye in the organic dye may be 0.01% to 50% by mass. The content of the second dye may be 0.01 to 10 parts by mass per 1 part by mass of the first dye. The content of the third dye may be 0.01 to 5 parts by mass per 1 part by mass of the first dye. [4] In the polarizing film described in any of [1] to [3] above, in the CIE-Lab color system, the orthogonal hue a ＊ The following equation (I) is satisfied, and the orthogonal hues b ＊ The following equation (II) may also be satisfied: 0.5 ≤ orthogonal hue a ＊ ≤ 5.5 ... (I) -20 ≤ orthogonal hue b ＊ ≤2.5...(II) [5] The thickness of the polarizing film described in any of [1] to [4] above may be 6 μm or less. [6] In the polarizing film described in any of [1] to [5] above, the single transmittance at a wavelength of 460 nm may be 44% or more. [7] In the polarizing film described in any of [1] to [6] above, the single transmittance at a wavelength of 460 nm may be 0.9 times or more than the single transmittance at a wavelength of 550 nm. [8] An optical laminate according to another aspect of the present invention comprises a polarizing plate and a phase difference film. The polarizing plate comprises a polarizing film described in any of [1] to [7] above. The phase difference film is located on one side in the thickness direction of the polarizing plate. [9] The thickness of the optical laminate described in [8] above may be 80 μm or less.

[10] An organic EL display device according to yet another aspect of the present invention comprises an optical laminate described in [8] or [9] above and an organic EL element. The organic EL element is positioned on the opposite side of the polarizer from the phase difference film. The reflectivity of the organic EL element may be 20% or less.

[0006] According to embodiments of the present invention, it is possible to realize a polarizing film, an optical laminate, and an organic EL display device that can suppress uneven dyeing and have excellent optical durability.

[0007] Figure 1 is a schematic cross-sectional view of a polarizing plate including a polarizing film according to one embodiment of the present invention. Figure 2 is a schematic cross-sectional view of an optical laminate comprising the polarizing plate of Figure 1. Figure 3 is a schematic cross-sectional view of an organic EL display device comprising the optical laminate of Figure 2. Figure 4 is a graph showing the transmittance curves of the polarizing plates obtained in the examples and comparative examples.

[0008] The following describes representative embodiments of the present invention, but the present invention is not limited to these embodiments. Furthermore, in order to clarify the explanation, the drawings may schematically represent the width, thickness, shape, etc., of each part compared to the embodiments; however, these are merely examples and do not limit the interpretation of the present invention.

[0009] (Definitions of Terms and Symbols) The definitions of terms and symbols used herein are as follows: (1) Refractive Index (nx, ny, nz) "nx" is the refractive index in the direction in which the refractive index in the plane is maximum (i.e., in the direction of the slow phase axis), "ny" is the refractive index in the direction perpendicular to the slow phase axis in the plane (i.e., in the direction of the fast phase axis), and "nz" is the refractive index in the thickness direction. (2) In-Plane Phase Difference (Re) "Re(λ)" is the in-plane phase difference measured with light of wavelength λnm at 23°C. For example, "Re(550)" is the in-plane phase difference measured with light of wavelength 550nm at 23°C. Re(λ) can be calculated by the formula: Re(λ) = (nx - ny) × d, where d (nm) is the thickness of the layer (film). (3) Phase Difference in the Thickness Direction (Rth) "Rth(λ)" is the phase difference in the thickness direction measured with light of wavelength λnm at 23°C. For example, "Rth(550)" is the phase difference in the thickness direction measured with light of a wavelength of 550 nm at 23°C. Rth(λ) is obtained by the formula: Rth(λ) = (nx - nz) × d, where d (nm) is the thickness of the layer (film). (4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re. (5) Angle When an angle is referred to herein, the angle includes both clockwise and counterclockwise with respect to the reference direction. Therefore, for example, "45°" means ±45°. (6) Substantially parallel or orthogonal The expressions "substantially orthogonal" and "approximately orthogonal" include the case where the angle between the two directions is 90° ± 10°, preferably 90° ± 7°, and more preferably 90° ± 5°. The expressions “substantially parallel” and “approximately parallel” encompass the case where the angle between the two directions is 0° ± 10°, preferably 0° ± 7°, and more preferably 0° ± 5°. Furthermore, when “orthogonal” or “parallel” is used in this specification, it may include substantially orthogonal or substantially parallel conditions.

[0010] A. Overview of Polarizing Film In one embodiment, the polarizing film comprises a polyvinyl alcohol-based resin (hereinafter sometimes referred to as PVA-based resin) and an organic dye. The organic dye comprises a first dye which is an azo compound having a ureid skeleton represented by the following formula (1) or a salt thereof. In equation (1), Ay １ and Ay ２ Each is independently a optionally substituted naphthyl group or an optionally substituted phenyl group, s and t are independently 0 or 1, and either s or t is 1, Ry １ ~Ry ８ Each independently represents a hydrogen atom or a substituent: The optionally substituted phenyl group is a phenyl group having at least one substituent selected from the group consisting of a sulfo group, a carboxyl group, a C1-C4 alkoxy group having a sulfo group, a C1-C4 alkyl group, a C1-C4 alkoxy group, a halogen atom, a nitro group, an amino group, a C1-C4 alkyl-substituted amino group, and a C1-C4 alkyl-substituted acylamino group; the optionally substituted naphthyl group is a naphthyl group having substituents selected from the group consisting of a hydroxyl group, a C1-C4 alkoxy group having a sulfo group, and a sulfo group: Ry １ , Ry ２ , Ry ７ , Ry ８ However, each is independently a hydrogen atom, a C1-C4 alkyl group, and a C1-C4 alkoxy group, and Ry ３ ~Ry ６ However, each of these is independently a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, and a C1-C4 alkoxy group having a sulfo group. In such a polarizing film, the thickness is 10 μm or less, the transmittance of the single element is 45% or more, and the degree of polarization is 95% or less.

[0011] The inventors discovered that when a polarizing film containing PVA resin and iodine is thinned and its transmittance is adjusted to 45% or more, uneven dyeing occurs in the polarizing film. When a polarizing film with uneven dyeing is applied to an image display device, it can cause uneven display in the image display device. Therefore, the inventors diligently investigated the occurrence of uneven dyeing in polarizing films and found that changing iodine to a specific organic dye can suppress uneven dyeing in the polarizing film. More specifically, since the polarizing film contains a PVA resin and an organic dye, and the organic dye contains the first dye mentioned above, even when the polarizing film is thinned to 10 μm or less and its transmittance is adjusted to 45% or more, uneven dyeing in the polarizing film can be sufficiently suppressed.

[0012] It is presumed that the suppression of uneven dyeing in such polarizing films occurs through the following mechanism. However, this presumption does not restrict the embodiments and mechanisms of the present invention. When a PVA-based resin is dyed with iodine, the iodine preferentially enters the smaller gaps between polymer chains present in the PVA-based resin before stretching (hereinafter referred to as the PVA polymer gap). Therefore, in the dyed PVA-based resin, the distribution of iodine may become non-uniform depending on the variation in the PVA polymer gap. Subsequently, when the dyed PVA-based resin is stretched to prepare a polarizing film, it is presumed that streaky uneven dyeing occurs because the polymer chains stretch and the iodine is oriented to form an iodine complex. In particular, when the transmittance of a single polarizing film is adjusted to 45% or more in a polarizing film with a thickness of 10 μm or less, uneven dyeing tends to become more pronounced. In contrast, the molecular size of the organic dye containing the first dye is larger than that of iodine, so when dyeing PVA resin, it is possible to suppress the penetration of the organic dye into the gaps between PVA polymers. Therefore, in the dyed PVA resin, the influence of variations in the gaps between PVA polymers on the distribution of the organic dye can be reduced, and the uniformity of the distribution of the organic dye can be improved. As a result, even when the thickness of a polarizing film prepared by stretching dyed PVA resin is set to 10 μm or less and the transmittance of the single film is adjusted to 45% or more, dyeing unevenness can be significantly suppressed.

[0013] Furthermore, in one embodiment, since the polarizing film contains a PVA-based resin and an organic dye, it is possible to suppress the occurrence of discoloration in heated environments (typically 60°C or higher) and / or humidified environments (typically 80% RH (relative humidity) or higher). In particular, it is possible to stably suppress the occurrence of discoloration at the edges of the polarizing film, where discoloration is relatively more likely to occur in heated and / or humidified environments. Therefore, the polarizing film has excellent optical durability.

[0014] In one embodiment, the polarizing film further comprises, in addition to the first dye described above, a second dye which is an azo compound represented by the following formula (2) or a salt thereof, and a third dye which is an azo compound represented by the following formula (3). In formula (2), Ar １１ Rr represents a substituted phenyl group or a substituted naphthyl group. １１ ~Rr １６ Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group, and Xr １１ represents an amino group which may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a benzoyl group which may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a phenylamino group which may have substituents selected from the group consisting of C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a benzoylamino group which may have substituents selected from the group consisting of C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a phenylazo group which may have substituents selected from the group consisting of C1-C4 alkoxy groups, sulfo groups, hydroxyl groups, amino groups, and substituted amino groups; or a naphthotriazole group which may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups, and m1 and n1 each independently represent 0 or 1, and when m1 and n1 are 1, Rr １５and Rr １６ Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group, and when m1 and n1 are 0, Rr １１ and Rr １２ Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group having a sulfo group. In equation (3), A is Ar in equation (2). １１ Similarly, or the following general formula (4) (In formula (4), A １ R is a substituent represented by (where represents a nitro group or an amino group), １ ~R ４ , R ６ Rr in the above formula (2) １１ ~Rr １４ Similarly, X is Xr of equation (2) above. １１ The same applies, where m and n are 0 or 1, respectively. When the polarizing film contains such first dye, second dye, and third dye, the polarizing film can be adjusted to a desired hue, and uneven dyeing in the polarizing film can be stably suppressed.

[0015] The organic dye may further contain pigments different from the first, second, and third dyes (hereinafter referred to as "other pigments"). Examples of other pigments include polymethine pigments, cyanine pigments, merocyanine pigments, rhodacyanine pigments, trinuclear merocyanine pigments, allopolar pigments, hemicyanine pigments, styryl pigments, and azo pigments. Other pigments may be used alone or in combination.

[0016] The PVA-based resin content in the polarizing film is, for example, 70% to 99% by mass, preferably 80% to 95% by mass.

[0017] The content of the first dye in the organic dye is, for example, 0.01% to 50% by mass, preferably 0.1% to 45% by mass, and more preferably 1% to 40% by mass. The content of the second dye is, for example, 0 to 10 parts by mass, preferably 0.01 to 10 parts by mass, more preferably 0.01 to 8 parts by mass, and even more preferably 0.1 to 5 parts by mass, per 1 part by mass of the first dye. The content of the third dye is, for example, 0 to 5 parts by mass, preferably 0.01 to 5 parts by mass, more preferably 0.01 to 4 parts by mass, and even more preferably 0.1 to 3 parts by mass, per 1 part by mass of the first dye. When the content of the first dye, the second dye, and the third dye are within these ranges, the orthogonal hue of the polarizing film can be stably adjusted to the range described later, and uneven dyeing in the polarizing film can be more stably suppressed. The respective content ratios of the first dye, second dye, and third dye are measured, for example, by high-performance liquid chromatography.

[0018] Orthogonal hue a of polarizing films in the CIE-Lab color system ＊ For example, it satisfies the following formula (I), preferably the following formula (I'), and more preferably the following formula (I''). 0.5 ≤ orthogonal hue a ＊ ≤ 5.5 ... (I) 1.0 ≤ orthogonal hue a ＊ ≤4.0...(I') 1.5 ≤ orthogonal hue a ＊ ≤3.0...(I'') Also, the orthogonal hue b of polarizing films in the CIE-Lab color system ＊ For example, it satisfies the following formula (II), preferably the following formula (II'), and more preferably the following formula (II''): -20 ≤ orthogonal hue b ＊ ≤2.5...(II) -19 ≤ orthogonal hue b ＊ ≤ 0 ... (II') - 18 ≤ orthogonal hue b ＊ ≤ -10...(II'') If the orthogonal hues of the polarizing film satisfy the above equation (I) and / or (II), uneven dyeing in the polarizing film can be further suppressed.

[0019] The polarization characteristics (single-layer transmittance and / or degree of polarization) of such polarizers are arbitrarily and appropriately adjusted according to the application of the polarizing film. The single-layer transmittance of the polarizing film is the average transmittance of visible light corrected for luminous efficiency, and is 45% or more, preferably 46% or more, more preferably 48% or more, and even more preferably 52% or more. On the other hand, the single-layer transmittance of the polarizing film is, for example, 90% or less, 80% or less, 70% or less, 65% or less, and 60% or less. The single-layer transmittance can be calculated, for example, as the Y value corrected for luminous efficiency by measuring with a 2-degree field of view (C light source) according to JIS Z8701. The degree of polarization of the polarizing film is, for example, 10% or more, preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, particularly preferably 50% or more, and especially preferably 60% or more. On the other hand, the degree of polarization of the polarizing film is 95% or less, 90% or less, and even preferably 80% or less.

[0020] The transmittance of the polarizing film at a wavelength of 460 nm is, for example, 43% or more, preferably 44% or more, more preferably 48% or more, even more preferably 50% or more, and particularly preferably 55% or more. On the other hand, the transmittance of the polarizing film at a wavelength of 460 nm is, for example, 95% or less, or for example, 90% or less. The transmittance of the polarizing film at a wavelength of 460 nm is, for example, 0.90 times or more, preferably 0.95 times or more, more preferably 1.00 times or more, even more preferably 1.02 times or more, and even more preferably 1.05 times or more compared to the transmittance of the polarizing film at a wavelength of 550 nm. On the other hand, the transmittance of the polarizing film at a wavelength of 460 nm is, for example, 1.5 times or less, or for example, 1.3 times or less, or for example, 1.1 times or less compared to the transmittance of the polarizing film at a wavelength of 550 nm. If the transmittance of the polarizing film at a wavelength of 460 nm is within this range, then when the polarizing film is applied to an organic EL display device, it is possible to extend the lifespan of the blue light-emitting material that can emit light at wavelengths of 430 nm to 490 nm, and as a result, extend the lifespan of the organic EL element.

[0021] The thickness of the polarizing film is 10 μm or less, preferably 8 μm or less, and more preferably 6 μm or less. The lower limit of the polarizing film thickness is typically 1 μm. When the thickness of the polarizing film is within this range, thermal shrinkage of the polarizing film can be suppressed, and defects such as cracks in the polarizing film can be suppressed. Furthermore, thickness variations of the polarizing film can be reduced, visibility can be improved, and the polarizing plate equipped with the polarizing film can be made thinner.

[0022] B. Details of the polarizing film The polarizing film contains a PVA-based resin and an organic dye, as described above. In addition to the PVA-based resin and organic dye, the polarizing film may also contain any suitable additives.

[0023] B-1. PVA-based resins PVA-based resins are typically capable of adsorbing the organic dyes described above and can function as an orientation substrate that orients the organic dyes by stretching. Examples of PVA-based resins include polyvinyl alcohol, acetal-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and ethylene-vinyl alcohol copolymers. These PVA-based resins may be used individually, or two or more PVA-based resins with different types of modification, modification rates, degrees of polymerization, and degrees of saponification may be used in combination.

[0024] In one embodiment, the PVA-based resin contains polyvinyl alcohol. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. The polyvinyl alcohol content in the PVA-based resin is, for example, 80% by mass or more, preferably 88% by mass or more. On the other hand, the polyvinyl alcohol content in the PVA-based resin is, for example, 100% by mass or less, for example 95% by mass or less, or for example 92% by mass or less.

[0025] The PVA-based resin may contain acetoacetyl-modified polyvinyl alcohol in addition to polyvinyl alcohol. The content of acetoacetyl-modified polyvinyl alcohol in the PVA-based resin is, for example, 5% by mass or more, preferably 8% by mass or more. On the other hand, the content of acetoacetyl-modified polyvinyl alcohol in the PVA-based resin is, for example, 20% by mass or less, preferably 12% by mass or less. When the content of acetoacetyl-modified polyvinyl alcohol in the PVA-based resin is within this range, the polarizing film can be stably dyed with organic dyes, and the mechanical strength of the polarizing film can be improved.

[0026] The degree of saponification of the PVA resin is, for example, 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%, and even more preferably 99.0 mol% to 99.5 mol%. By using a PVA resin with such a degree of saponification, a thin polarizing film with excellent optical durability can be realized. The degree of saponification is measured, for example, in accordance with JIS K 6726-1994.

[0027] The average degree of polymerization of PVA resins can be appropriately selected depending on the purpose. For example, the average degree of polymerization of PVA resins is 1000 or more, preferably 1500 or more, more preferably 2000 or more, and even more preferably 3000 or more. On the other hand, the average degree of polymerization of PVA resins is 10000 or less, preferably 6000 or less, and even more preferably 4300 or less. The average degree of polymerization is measured, for example, in accordance with JIS K 6726-1994.

[0028] The orientation function of the PVA resin contained in the polarizing film is, for example, 0.40 or less, preferably 0.38 or less, more preferably 0.35 or less, even more preferably 0.30 or less, and particularly preferably 0.28 or less. The lower limit of the orientation function of the PVA resin in the polarizing film is typically 0.20. If the PVA resin of the polarizing film has such an orientation function, the thermal shrinkage of the polarizing film can be stably suppressed. The orientation function of the PVA resin can be determined, for example, by using a Fourier transform infrared spectrophotometer (FT-IR) and measuring attenuated total reflection (ATR) using the polarization as the measurement light. Specifically, measurements are performed with the stretching direction of the polarizing film parallel and perpendicular to the polarization direction of the measurement light, and the 2941 cm⁻¹ of the obtained absorbance spectrum is measured. －１ The intensity is used to calculate the following according to the formula below. Here, intensity I is 3330 cm －１ Using the reference peak as 2941 cm －１ / 3330cm －１ This is the value of f. Note that when f=1, the orientation is perfect, and when f=0, it is random. Also, 2941 cm －１ The peak is the main chain of PVA in the polarizing film (-CH ２ It is thought that this absorption is caused by the vibration of -). f = (3 < cos ２ θ > -1) / 2 = (1 - D) / [c(2D + 1)] = -2 × (1 - D) / (2D + 1) where c = (3cos ２ β-1) / 2, 2941 cm －１ In the case of vibration, β = 90°. θ: Angle of the molecular chain with respect to the stretching direction β: Angle of the transition dipole moment with respect to the molecular chain axis D = (I ⊥ ) / (I / / (In this case, the more the PVA molecules are oriented, the larger D becomes.) ⊥ Absorption intensity when the polarization direction of the measured light and the stretching direction of the polarizing film are perpendicular. / / : Absorption intensity when the polarization direction of the measured light and the stretching direction of the polarizing film are parallel.

[0029] B-2. Organic Dye B-2-1. First Dye The first dye is an azo compound having a ureido skeleton represented by the above formula (1) or a salt thereof. When the organic dye contains the first dye, in a polarizing film containing a PVA-based resin, the organic dye can be appropriately oriented, and excellent polarization characteristics can be exhibited over the visible light range. In particular, the single transmittance of the polarizing film can be stably adjusted within the above-described range.

[0030] Such first dyes include, for example, the azo compounds or salts thereof described in International Publication No. 2019 / 124161. The entire description of this publication is incorporated herein by reference. In one aspect, preferably, in the above formula (1), Ay １ and Ay ２ are each independently a phenyl group which may have a substituent selected from the group consisting of an alkoxy group having 1 to 4 carbon atoms having a sulfo group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a carboxy group, a halogen group, a nitro group, a sulfo group, a substituted or unsubstituted amino group, and an amide group, s and t are each independently 0 or 1, and either s or t is 1, Ry １ , Ry ２ , Ry ７ , and Ry ８ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and Ry ３ to Ry ６ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms having a sulfo group. More preferably, Ay １ and Ay ２ are each independently a phenyl group which may have a substituent selected from the group consisting of a carboxy group, a halogen group, and a sulfo group, s and t are each independently 0 or 1, and either s or t is 1, Ry １ , Ry ２ , Ry ７ , and Ry ８ are each independently a hydrogen atom, a methyl group, or a methoxy group, and Ry ３ to Ry ６is independently a hydrogen atom, a methyl group, a methoxy group, or a 3-sulfopropoxy group. More preferably, Ay １ and Ay ２ are independently a 4-sulfophenyl group, a 4-carboxyphenyl group, a 4-chloro-4-carboxyphenyl group, or a 2,4-disulfophenyl group, s and t are independently 0 or 1, and either s or t is 1, Ry １ 、Ry ２ 、Ry ７ 、and Ry ８ are independently a hydrogen atom, a methyl group, or a methoxy group, Ry ３ ~Ry ６ are independently a hydrogen atom, a methyl group, a methoxy group, or a 3-sulfopropoxy group. Particularly preferably, Ay １ and Ay ２ are each a combination of a 4-sulfophenyl group and a 4-carboxyphenyl group, a combination of a 4-carboxyphenyl group and a 4-chloro-3-carboxyphenyl group, a combination of a 4-sulfophenyl group and a 4-chloro-3-carboxyphenyl group, or a combination of a 4-carboxyphenyl group and a 2,4-disulfophenyl group, s and t are independently 0 or 1, and either s or t is 1, Ry １ 、Ry ２ 、Ry ７ 、and Ry ８ are independently a hydrogen atom, a methyl group, or a methoxy group, Ry ３ ~Ry ６ are independently a hydrogen atom, a methyl group, a methoxy group, or a 3-sulfopropoxy group. In one embodiment, preferably, in the above formula (1), Ay １ and Ay ２However, each may independently be a naphthyl group having substituents selected from the group consisting of alkoxy groups having a sulfo group and a sulfo group, or a phenyl group having a sulfo group having a sulfo group and a sulfo group, a alkoxy group having a sulfo group and a sulfo group having a sulfo group having a sulfo group having a sulfo group having a sulfo group having a sulfo alkyl group having a sulfo. Ay1 or Ay2 is a naphthyl group having substituents selected from the group consisting of alkoxy groups having a sulfo group and a sulfo group having a sulfo group, s and t are each independently 0 or 1, and either s or t is 1, and Ry １ , Ry ２ , Ry ７ , and Ry ８ However, each is independently a hydrogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group, and Ry ３ ~Ry ６ However, each is independently a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group. More preferably, Ay １ and Ay ２ However, each may independently be a naphthyl group having substituents selected from the group consisting of alkoxy groups having 1 to 4 carbon atoms and sulfo groups, or a phenyl group having substituents selected from the group consisting of carboxyl groups, halogen groups, and sulfo groups. １ and or Ay ２ Either of them is a naphthyl group which may have substituents selected from the group consisting of alkoxy groups having 1 to 4 carbon atoms and sulfo groups, s and t are each independently 0 or 1, and either s or t is 1, Ry １ , Ry ２ , Ry ７ , and Ry ８ However, each is independently a hydrogen atom, a methyl group, or a methoxy group, and Ry ３ ~Ry ６ However, each is independently a hydrogen atom, a methyl group, a methoxy group, or a 3-sulfopropoxy group. More preferably, Ay １ and Ay ２However, each naphthyl group may independently have substituents selected from the group consisting of 3-sulfopropoxy groups and sulfo groups, and s and t are each independently 0 or 1, and either s or t is 1, Ry １ , Ry ２ , Ry ７ , and Ry ８ However, each is independently a hydrogen atom, a methyl group, or a methoxy group, and Ry ３ ~Ry ６ However, each is independently a hydrogen atom, a methyl group, a methoxy group, or a 3-sulfopropoxy group. Particularly preferred is Ay １ and Ay ２ However, each is 6,8-disulfonaphthalene or 6-sulfo-8-(3-sulfopropoxy)naphthalene, and s and t are each independently 0 or 1, and either s or t is 1, Ry １ , Ry ２ , Ry ７ , and Ry ８ However, each is independently a hydrogen atom, a methyl group, or a methoxy group, and Ry ３ ~Ry ６ However, each is independently a hydrogen atom, a methyl group, a methoxy group, or a 3-sulfopropoxy group. Very preferably, Ay １ and Ay ２ However, each is 6,8-disulfonaphthalene or 6-sulfo-8-(3-sulfopropoxy)naphthalene, and s and t are each 1, Ry １ , Ry ２ , Ry ７ , and Ry ８ However, each is independently a hydrogen atom, a methyl group, or a methoxy group, and Ry ３ ~Ry ６ However, each of these is independently a hydrogen atom, a methyl group, a methoxy group, or a 3-sulfopropoxy group.

[0031] Examples of such first dyes include the following compound examples 1 to 268. (Compound Example 1) (Compound example 2) (Compound example 3) (Compound example 4) (Compound example 5) (Compound example 6) (Compound Example 7) (Compound Example 8) (Compound Example 9) (Compound Example 10) (Compound Example 11) (Compound Example 12) (Compound Example 13) (Compound Example 14) (Compound Example 15) (Compound Example 16) (Compound Example 17) (Compound Example 18) (Compound Example 19) (Compound Example 20) (Compound Example 21) (Compound Example 22) (Compound Example 23) (Compound Example 24) (Compound Example 25) (Compound Example 26) (Compound Example 27) (Compound Example 28) (Compound Example 29) (Compound Example 30) (Compound Example 31) (Compound Example 32) (Compound Example 33) (Compound Example 34) (Compound Example 35) (Compound Example 36) (Compound Example 37) (Compound Example 38) (Compound Example 39) (Compound Example 40) (Compound Example 41) (Compound Example 42) (Compound Example 43) (Compound Example 44) (Compound Example 45) (Compound Example 46) (Compound Example 47) (Compound Example 48) (Compound Example 49) (Compound Example 50) (Compound Example 51) (Compound Example 52) (Compound Example 53) (Compound Example 54) (Compound Example 55) (Compound Example 56) (Compound Example 57) (Compound Example 58) (Compound Example 59) (Compound Example 60) (Compound Example 61) (Compound Example 62) (Compound Example 63) (Compound Example 64) (Compound Example 65) (Compound Example 66) (Compound Example 67) (Compound Example 68) (Compound Example 69) (Compound Example 70) (Compound Example 71) (Compound Example 72) (Compound Example 73) (Compound Example 74) (Compound Example 75) (Compound Example 76) (Compound Example 77) (Compound Example 78) (Compound Example 79) (Compound Example 80) (Compound Example 81) (Compound Example 82) (Compound Example 83) (Compound Example 84) (Compound Example 85) (Compound Example 86) (Compound Example 87) (Compound Example 88) (Compound Example 89) (Compound Example 90) (Compound Example 91) (Compound Example 92) (Compound Example 93) (Compound Example 94) (Compound Example 95) (Compound Example 96) (Compound Example 97) (Compound Example 98) (Compound Example 99) (Compound Example 100) (Compound Example 101) (Compound Example 102) (Compound Example 103) (Compound Example 104) (Compound Example 105) (Compound Example 106) (Compound Example 107) (Compound Example 108) (Compound Example 109) (Compound Example 110) (Compound Example 111) (Compound Example 112) (Compound Example 113) (Compound Example 114) (Compound Example 115) (Compound Example 116) (Compound Example 117) (Compound Example 118) (Compound Example 119) (Compound Example 120) (Compound Example 121) (Compound Example 122) (Compound Example 123) (Compound Example 124) (Compound Example 125) (Compound Example 126) (Compound Example 127) (Compound Example 128) (Compound Example 129) (Compound Example 130) (Compound Example 131) (Compound Example 132) (Compound Example 133) (Compound Example 134) (Compound Example 135) (Compound Example 136) (Compound Example 137) (Compound Example 138) (Compound Example 139) (Compound Example 140) (Compound Example 141) (Compound Example 142) (Compound Example 143) (Compound Example 144) (Compound Example 145) (Compound Example 146) (Compound Example 147) (Compound Example 148) (Compound Example 149) (Compound Example 150) (Compound Example 151) (Compound Example 152) (Compound Example 153) (Compound Example 154) (Compound Example 155) (Compound Example 156) (Compound Example 157) (Compound Example 158) (Compound Example 159) (Compound Example 160) (Compound Example 161) (Compound Example 162) (Compound Example 163) (Compound Example 164) (Compound Example 165) (Compound Example 166) (Compound Example 167) (Compound Example 168) (Compound Example 169) (Compound Example 170) (Compound Example 171) (Compound Example 172) (Compound Example 173) (Compound Example 174) (Compound Example 175) (Compound Example 176) (Compound Example 177) (Compound Example 178) (Compound Example 179) (Compound Example 180) (Compound Example 181) (Compound Example 182) (Compound Example 183) (Compound Example 184) (Compound Example 185) (Compound Example 186) (Compound Example 187) (Compound Example 188) (Compound Example 189) (Compound Example 190) (Compound Example 191) (Compound Example 192) (Compound Example 193) (Compound Example 194) (Compound Example 195) (Compound Example 196) (Compound Example 197) (Compound Example 198) (Compound Example 199) (Compound Example 200) (Compound Example 201) (Compound Example 202) (Compound Example 203) (Compound Example 204) (Compound Example 205) (Compound Example 206) (Compound Example 207) (Compound Example 208) (Compound Example 209) (Compound Example 210) (Compound Example 211) (Compound Example 212) (Compound Example 213) (Compound Example 214) (Compound Example 215) (Compound Example 216) (Compound Example 217) (Compound Example 218) (Compound Example 219) (Compound Example 220) (Compound Example 221) (Compound Example 222) (Compound Example 223) (Compound Example 224) (Compound Example 225) (Compound Example 226) (Compound Example 227) (Compound Example 228) (Compound Example 229) (Compound Example 230) (Compound Example 231) (Compound Example 232) (Compound Example 233) (Compound Example 234) (Compound Example 235) (Compound Example 236) (Compound Example 237) (Compound Example 238) (Compound Example 239) (Compound Example 240) (Compound Example 241) (Compound Example 242) (Compound Example 243) (Compound Example 244) (Compound Example 245) (Compound Example 246) (Compound Example 247) (Compound Example 248) (Compound Example 249) (Compound Example 250) (Compound Example 251) (Compound Example 252) (Compound Example 253) (Compound Example 254) (Compound Example 255) (Compound Example 256) (Compound Example 257) (Compound Example 258) (Compound Example 259) (Compound Example 260) (Compound Example 261) (Compound Example 262) (Compound Example 263) (Compound Example 264) (Compound Example 265) (Compound Example 266) (Compound Example 267) (Compound Example 268)

[0032] These first dyes can be used individually or in combination. Among the first dyes, preferred examples include Compound Example 25, Compound Example 140, Compound Example 167, Compound Example 177, Compound Example 180, and Compound Example 241.

[0033] B-2-2. Second Dye The second dye is an azo compound represented by formula (2) above or a salt thereof. When the organic dye contains the second dye, the desired polarization characteristics and hue can be stably expressed in a polarizing film containing a PVA resin. In particular, the orthogonal hue a of the polarizing film ＊ and b ＊ Each of these can be stably adjusted to the ranges described above.

[0034] In the above general formula (2), Ar １１ Rr represents a substituted phenyl group or a substituted naphthyl group. １１ ~Rr １６ Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group, and Xr11 may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups, a benzoyl group may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups, or a substituent selected from the group consisting of C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups. This represents a benzoylamino group which may have substituents selected from the group consisting of a good phenylamino group, a C1-C4 alkoxy group, a sulfo group, an amino group, and a substituted amino group, a phenylazo group which may have substituents of any of a C1-C4 alkyl group, a C1-C4 alkoxy group, a sulfo group, a hydroxyl group, an amino group, or a substituted amino group, or a naphthotriazole group which may have substituents selected from the group consisting of a C1-C4 alkyl group, a C1-C4 alkoxy group, a sulfo group, an amino group, and a substituted amino group, where m1 and n1 each independently represent 0 or 1, and when m1 and n1 are 1, Rr １５ and Rr１６ Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group having a sulfo group. １１ Ar represents a substituted phenyl group or a substituted naphthyl group, but １１ When the substituent is a phenyl group, it is preferable that the phenyl group has at least one sulfo group or carboxyl group as a substituent. When the phenyl group has two or more substituents, it is preferable that at least one of the substituents is a sulfo group or a carboxyl group, and the other substituents are a sulfo group, a carboxyl group, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C1-C4 alkoxy group having a sulfo group, a hydroxyl group, a nitro group, an amino group, or a substituted amino group (particularly an acetylamino group or a C1-C4 alkylamino group). It is more preferable that the other substituents are a sulfo group, a carboxyl group, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a hydroxyl group, a nitro group, or an amino group, and particularly preferable that they are a sulfo group, a carboxyl group, a methyl group, a methoxy group, or an ethoxy group. Furthermore, as the C1-C4 alkoxy group having a sulfo group, a linear alkoxy group is preferred, and the substitution position of the sulfo group is preferably at the alkoxy group terminus. As the alkoxy group having a sulfo group and having 1 to 4 carbon atoms, a 3-sulfopropoxy group or a 4-sulfobutoxy group is more preferred, and the 3-sulfopropoxy group is particularly preferred. The number of substituents on the phenyl group is preferably 1 or 2, and the position of the substituent on the phenyl group is not particularly limited, but it is preferably only at the 4-position, a combination of the 2-position and the 4-position, or a combination of the 3-position and the 5-position. Ar １１When the naphthyl group has substituents, it is preferable that the naphthyl group has at least one sulfo group as a substituent, and when the naphthyl group has two or more substituents, it is preferable that at least one of the substituents is a sulfo group and the other substituents are a sulfo group, a hydroxyl group, a carboxyl group, or a C1-C4 alkoxy group having a sulfo group. Furthermore, as the C1-C4 alkoxy group having a sulfo group, a linear alkoxy group is preferred, and the substitution position of the sulfo group is preferably at the alkoxy group terminus. As the C1-C4 alkoxy group having a sulfo group, a 3-sulfopropoxy group or a 4-sulfobutoxy group is more preferred, and the 3-sulfopropoxy group is particularly preferred. When the number of sulfo groups on the naphthyl group is two, the substitution positions of the sulfo groups are preferably a combination of the 4- and 8-positions or a combination of the 6- and 8-positions, and the combination of the 6- and 8-positions is particularly preferred. When the number of sulfo groups on the naphthyl group is three, the substitution positions of the sulfo groups are particularly preferably a combination of positions 1-, 3-, and 6-. １１ Xr represents an amino group which may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a benzoyl group which may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a phenylamino group which may have substituents selected from the group consisting of C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a benzoylamino group which may have substituents selected from the group consisting of C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a phenylazo group which may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, hydroxyl groups, amino groups, and substituted amino groups; or a naphthotriazole group which may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups. １１It is preferable that the amino group may have one or two substituents selected from the group consisting of a methyl group, a methoxy group, a sulfo group, an amino group, and an alkylamino group having 1 to 4 carbon atoms; a phenylamino group may have one or two substituents selected from the group consisting of a methyl group, a methoxy group, a sulfo group, an amino group, and an alkylamino group having 1 to 4 carbon atoms; a benzoyl group may have one substituent selected from the group consisting of an amino group and a carboxyethylamino group; or a phenylazo group may have one to three substituents selected from the group consisting of a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an amino group, and a carboxyethylamino group. １１ It is preferable that Xr11 is a phenylamino group which may have substituents selected from the group consisting of alkoxy groups, sulfo groups, amino groups, and substituted amino groups having 1 to 4 carbon atoms, a benzoyl group which may have substituents selected from the group consisting of alkoxy groups, sulfo groups, amino groups, and substituted amino groups having 1 to 4 carbon atoms, or a benzoylamino group which may have substituents selected from the group consisting of alkoxy groups, sulfo groups, amino groups, and substituted amino groups having 1 to 4 carbon atoms, and it is particularly preferable that it is a phenylamino group which may have substituents. Furthermore, it is even more preferable that Xr11 is a benzoyl group which may have substituents selected from the group consisting of amino groups and substituted amino groups, or a benzoylamino group which may have substituents selected from the group consisting of amino groups and substituted amino groups. １１If the substituent is selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups, then the substituent on the phenyl group is not particularly limited, but it is especially preferable that it be at the p-position of the phenyl group relative to the amino group. １１ ~Rr １６ Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group. Preferably, it is a hydrogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group, and more preferably, a hydrogen atom, a methyl group, or a methoxy group. As the C1-C4 alkoxy group having a sulfo group, a linear alkoxy group is preferred, and the substitution position of the sulfo group is preferably at the alkoxy group terminus. As the C1-C4 alkoxy group having a sulfo group, a 3-sulfopropoxy group or a 4-sulfobutoxy group is more preferred, and a 3-sulfopropoxy group is particularly preferred. m1 and n1 may each independently be 0 or 1. To obtain appropriate polarization performance in the polarizing film (polarizing element) of this embodiment, it is preferable that if either m1 or n1 is 0, the other is 1. Note that when m1 and n1 are 1, in order for the polarizing film (polarizing element) of this embodiment to exhibit the desired performance, Rr １５ and Rr １６Each of these must independently be a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group, and it is preferable that it be a hydrogen atom or a methyl group. As for the C1-C4 alkyl group, the C1-C4 alkoxy group, and the C1-C4 alkoxy group having a sulfo group, it is preferable that the C1-C3 alkyl group, the C1-C3 alkoxy group, and the C3 or C4 alkoxy group having a sulfo group. Furthermore, the substituted amino group is not particularly limited. Examples of substituted amino groups include amino groups substituted with C1-C4 alkyl groups and amino groups substituted with acyl groups. The method for synthesizing the azo compound in which the form of the free acid is represented by general formula (2) is not particularly limited. Examples of methods for synthesizing azo compounds whose free acid is represented by general formula (2) include those described in Japanese Patent Publication No. 9-302250, Japanese Patent No. 2622748, Japanese Patent No. 4662853, International Publication No. 2012 / 108169, and International Publication No. 2012 / 108173. Examples of azo compounds whose free acid is represented by general formula (2) include C.I. Direct Red 117, C.I. Direct Red 127, the azo compound described in Japanese Patent No. 2622748, the azo compound described in Japanese Patent No. 4662853, and the azo compound described in International Publication No. 2012 / 108169. Next, specific examples of azo compounds whose free acid is represented by general formula (2) are listed below.

[0035] (Compound Example 269) (Compound Example 270) (Compound Example 271) (Compound Example 272) (Compound Example 273) (Compound Example 274) (Compound Example 275) (Compound Example 276) (Compound Example 277) (Compound Example 278) (Compound Example 279) (Compound Example 280) (Compound Example 281) (Compound Example 282) (Compound Example 283) (Compound Example 284) (Compound Example 285) (Compound Example 286) (Compound Example 287) (Compound Example 288) (Compound Example 289) (Compound Example 290) (Compound Example 291) (Compound Example 292) (Compound Example 293) (Compound Example 294) (Compound Example 295) (Compound Example 296) (Compound Example 297) (Compound Example 298) (Compound Example 299) (Compound Example 300) (Compound Example 301) (Compound Example 302) (Compound Example 303) (Compound Example 304) (Compound Example 305) (Compound Example 306) (Compound Example 307) (Compound Example 308) (Compound Example 309) (Compound Example 310) (Compound Example 311) (Compound Example 312) (Compound Example 313) (Compound Example 314) (Compound Example 315) (Compound Example 316) (Compound Example 317) (Compound Example 318) (Compound Example 319) (Compound Example 320) (Compound Example 321) (Compound Example 322) (Compound Example 323) (Compound Example 324) (Compound Example 325) (Compound Example 326) (Compound Example 327) (Compound Example 328) (Compound Example 329) (Compound Example 330) (Compound Example 331) (Compound Example 332) (Compound Example 333) (Compound Example 334) (Compound Example 335) (Compound Example 336) (Compound Example 337) (Compound Example 338) (Compound Example 339) (Compound Example 340) (Compound Example 341) (Compound Example 342) (Compound Example 343) (Compound Example 344) (Compound Example 345) (Compound Example 346) (Compound Example 347) (Compound Example 348) (Compound Example 349) (Compound Example 350) (Compound Example 351) (Compound Example 352) (Compound Example 353) (Compound Example 354) (Compound Example 355) (Compound Example 356) (Compound Example 357) (Compound Example 358) (Compound Example 359) (Compound Example 360) (Compound Example 361) (Compound Example 362) (Compound Example 363) (Compound Example 364) (Compound Example 365) (Compound Example 366) (Compound Example 367) (Compound Example 368) (Compound Example 369) (Compound Example 370) (Compound Example 371) (Compound Example 372) (Compound Example 373) (Compound Example 374) (Compound Example 375) (Compound Example 376) (Compound Example 377) (Compound Example 378) (Compound Example 379) (Compound Example 380) (Compound Example 381) (Compound Example 382) (Compound Example 383) (Compound Example 384) (Compound Example 385) (Compound Example 386) (Compound Example 387) (Compound Example 388) (Compound Example 389) (Compound Example 390) (Compound Example 391) (Compound Example 392) (Compound Example 393) (Compound Example 394) (Compound Example 395) (Compound Example 396) (Compound Example 397) (Compound Example 398) (Compound Example 399) (Compound Example 400) (Compound Example 401) (Compound Example 402) (Compound Example 403) (Compound Example 404) (Compound Example 405) (Compound Example 406) (Compound Example 407) (Compound Example 408) (Compound Example 409) (Compound Example 410) (Compound Example 411) (Compound Example 412) (Compound Example 413) (Compound Example 414) (Compound Example 415) (Compound Example 416) (Compound Example 417) (Compound Example 418) (Compound Example 419) (Compound Example 420) (Compound Example 421) (Compound Example 422) (Compound Example 423) (Compound Example 424) (Compound Example 425) (Compound Example 426) (Compound Example 427) (Compound Example 428) (Compound Example 429) (Compound Example 430) (Compound Example 431) (Compound Example 432) (Compound Example 433) (Compound Example 434) (Compound Example 435) (Compound Example 436) (Compound Example 437)

[0036] These second dyes can be used individually or in combination. Among the second dyes, preferred examples include compound example 269, compound example 270, compound example 303, compound example 311, compound example 384, and compound example 396.

[0037] B-2-3. Third Dye The third dye is an azo compound represented by formula (3) above or a salt thereof. In formula (3), A is Ar of formula (2) above. １１ Similar to, or the above formula (4), R １ ~R ４ , R ６ Rr in the above formula (2) １１ ~Rr １４ This is similar to what is shown, and X is Xr in equation (2) above. １１The same applies, where m and n are 0 or 1, respectively. When the organic dye contains a third dye, the desired polarization characteristics and hue can be more stably expressed in a polarizing film containing a PVA resin. In particular, the orthogonal hue a of the polarizing film ＊ and b ＊ Each of these can be stably adjusted according to the above relationship. Specific examples of such third dyes are given below.

[0038] (Compound Example 438) (Compound Example 439) (Compound Example 440) (Compound Example 441) (Compound Example 442) (Compound Example 443) (Compound Example 444) (Compound Example 445) (Compound Example 446) (Compound Example 447) (Compound Example 448) (Compound Example 449) (Compound example 450) (Compound Example 451) (Compound Example 452) (Compound Example 453) (Compound Example 454) (Compound Example 455) (Compound Example 456) (Compound Example 457) (Compound Example 458) (Compound Example 459) (Compound Example 460) (Compound Example 461) (Compound Example 462) (Compound Example 463) (Compound Example 464) (Compound Example 465) (Compound Example 466) (Compound Example 467) (Compound Example 468) (Compound Example 469) (Compound Example 470)

[0039] These third dyes can be used individually or in combination. Among the third dyes, preferred examples include compound example 454, compound example 455, compound example 441, and compound example 465.

[0040] The azo compounds shown in the above examples of the first to third dyes may be in the form of free acids or salts. Examples of such salts include alkali metal salts such as lithium salts, sodium salts, and potassium salts, and organic salts such as ammonium salts and amine salts, with sodium salts being preferred.

[0041] In one embodiment, the organic dye comprises one first dye, two or more second dyes (preferably two second dyes), and one third dye. Preferred combinations of the one first dye, two second dyes, and one third dye are shown in Table 1 below.

[0042] C. Method for Manufacturing a Polarizing Film Next, a method for manufacturing a polarizing film according to one embodiment will be described. In one embodiment, the method for manufacturing a polarizing film includes, in this order, a laminate manufacturing step, a dry stretching step, a dyeing step, a wet stretching step, and a drying shrinkage step. According to such a manufacturing method, a polarizing film having the thickness and polarizing properties described above can be stably manufactured. Such a method for manufacturing a polarizing film preferably further includes a swelling step and / or a crosslinking step. The swelling step is typically performed after the dry stretching step and before the dyeing step. The crosslinking step is typically performed after the dyeing step and before the wet stretching step. The method for manufacturing a polarizing film may also further include a washing step. The washing step is typically performed after the wet stretching step and before the drying shrinkage step.

[0043] C-1. Laminate Fabrication Process In the laminate fabrication process, the coating solution containing the PVA-based resin described above is applied to a long resin substrate using any appropriate method.

[0044] The coating solution is typically a solution of the PVA-based resin described above dissolved in a solvent. Examples of solvents include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. The solvent can be used alone or in combination. Among the solvents, water is preferred.

[0045] The PVA-based resin content in the coating solution is, for example, 3 to 20 parts by mass per 100 parts by mass of solvent. With such a resin concentration, a uniform coating film that adheres closely to the resin substrate can be formed.

[0046] Furthermore, additives may be added to the coating solution. Examples of additives include plasticizers and surfactants. Examples of plasticizers include polyhydric alcohols such as ethylene glycol and glycerin. Examples of surfactants include nonionic surfactants.

[0047] The resin substrate is composed of any suitable material. Typical constituent materials of the resin substrate include amorphous (non-crystallized) polyethylene terephthalate resins, and preferably amorphous (less crystallized) polyethylene terephthalate resins. Specific examples of amorphous polyethylene terephthalate resins include copolymers further containing isophthalic acid as a dicarboxylic acid, and copolymers further containing cyclohexanedimethanol as a glycol. Among the resin substrates, amorphous isophthal copolymer polyethylene terephthalate film resin substrates are preferred.

[0048] The glass transition temperature (Tg) of the resin substrate is, for example, 170°C or lower, preferably 120°C or lower. Having such a Tg allows for sufficient stretchability of the laminate while suppressing excessive crystallization of the PVA-based resin layer. Furthermore, the glass transition temperature (Tg) of the resin substrate is typically 60°C or higher. This suppresses defects such as deformation of the resin substrate (e.g., unevenness, sagging, or wrinkles) when the coating solution is applied to and dried on the resin substrate. The glass transition temperature (Tg) is measured, for example, in accordance with JIS K 7121.

[0049] The thickness of the resin substrate before stretching is, for example, 20 μm or more, preferably 50 μm or more. On the other hand, the thickness of the resin substrate before stretching is, for example, 300 μm or less, preferably 200 μm or less. The surface of the resin substrate may be subjected to any appropriate surface treatment (e.g., corona treatment), and an easy-adhesion layer may be formed. This can improve the adhesion between the resin substrate and the PVA-based resin layer. Preferably, the surface of the resin substrate is subjected to corona treatment.

[0050] The coating film (coating liquid) formed on the resin substrate is dried at an appropriate drying temperature as needed. The drying temperature is, for example, between 50°C and 100°C.

[0051] This process produces a laminate comprising a PVA-based resin layer and a resin substrate. The thickness of the PVA-based resin layer before dry stretching is, for example, 3 μm or more, preferably 5 μm or more. On the other hand, the thickness of the PVA-based resin layer before dry stretching is, for example, 40 μm or less, preferably 30 μm or less.

[0052] C-2. Dry stretching process In the dry stretching process, a laminate comprising a PVA-based resin layer and a resin substrate is stretched in the air in the longitudinal direction. In other words, the dry stretching process is an air stretching process.

[0053] The stretching method in the dry stretching process may be fixed-end stretching (for example, stretching using a tenter stretcher) or free-end stretching (for example, uniaxial stretching by passing the laminate between rolls with different peripheral speeds).

[0054] The stretching temperature in the dry stretching process is typically above the glass transition temperature (Tg) of the PVA resin. The stretching temperature in the dry stretching process is, for example, 95°C or higher, preferably 120°C or higher. On the other hand, the upper limit of the stretching temperature in the dry stretching process is typically 150°C. The stretching ratio of the laminate in the dry stretching process is, for example, 2.1 times or higher, preferably 2.3 times or higher. On the other hand, the stretching ratio of the laminate in the dry stretching process is, for example, 4.0 times or less, preferably 3.0 times or less. If the stretching ratio of the laminate is within this range, the orientation of the PVA resin layer contained in the laminate can be suitably adjusted.

[0055] The crystallization index of the PVA-based resin layer after the dry stretching process and before the dyeing process is, for example, 0.50 or less, preferably 0.48 or less, more preferably 0.40 or less, and even more preferably 0.38 or less. The lower limit of the crystallization index of the PVA-based resin layer is typically 0.20. The orientation function of the PVA-based resin layer after the dry stretching process and before the dyeing process is typically smaller than the orientation function of the polarizing film described above. The orientation function of the PVA-based resin layer after the dry stretching process and before the dyeing process is, for example, 0.35 or less, preferably 0.28 or less, and more preferably 0.24 or less. On the other hand, the lower limit of the orientation function of the PVA-based resin layer after the dry stretching process and before the dyeing process is typically 0.15. If the crystallization index and / or orientation function of the PVA-based resin layer after the dry stretching process and before the dyeing process are within this range, the organic dye can uniformly and stably dye the PVA-based resin layer in the dyeing process.

[0056] C-3. Swelling Process In the swelling process, the laminate is typically immersed in a swelling solution (swelling bath). The swelling solution is typically water. The temperature of the swelling bath is, for example, 10°C or higher, preferably 20°C or higher. On the other hand, the temperature of the swelling bath is, for example, 60°C or lower, preferably 50°C or lower. The immersion time in the swelling process is, for example, 10 seconds or more, preferably 20 seconds or more. On the other hand, the immersion time in the swelling process is, for example, 200 seconds or less, preferably 60 seconds or less.

[0057] Alternatively, an immobilization step may be performed instead of the swelling step. In the immobilization step, the laminate is typically immersed in an immobilization solution (immobilization bath). The immobilization solution is typically an aqueous boric acid solution. The boric acid content in the immobilization solution is, for example, 1 to 10 parts by mass per 100 parts by mass of water. The temperature range of the immobilization bath is, for example, the same as the temperature range of the swelling bath described above. The immersion time range in the immobilization step is, for example, the same as the immersion time range in the swelling step described above.

[0058] C-4. Dyeing Process In the dyeing process, the PVA resin layer after the dry stretching process (preferably after the swelling process) is dyed with the organic dye described above. Specifically, the PVA resin layer is brought into contact with a dyeing solution containing the organic dye described above to adsorb the organic dye.

[0059] The dyeing solution is typically an aqueous solution of organic dye in which the above-mentioned organic dye is dissolved in water. The content of organic dye in the dyeing solution is, for example, 0.01% by mass or more, preferably 0.05% by mass or more. On the other hand, the content of organic dye in the dyeing solution is, for example, 4% by mass or less, preferably 2% by mass or less.

[0060] In one embodiment, the dyeing solution contains at least the first dye described above. Preferably, the dyeing solution further contains the second and third dyes described above in addition to the first dye. The proportion of each dye is appropriately adjusted according to the desired transmittance and / or hue of the polarizing film. The proportion of the first dye in the dyeing solution is, for example, 0.01% by mass or more, preferably 0.05% by mass or more, while the proportion of the first dye in the dyeing solution is, for example, 4% by mass or less, preferably 2% by mass or less. The proportion of the second dye is, for example, 0.1 parts by mass or more, preferably 0.2 parts by mass or more, per 1 part by mass of the first dye. On the other hand, the proportion of the second dye is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, per 1 part by mass of the first dye. The proportion of the third dye is, for example, 0.1 parts by mass or more, preferably 0.2 parts by mass or more, per 1 part by mass of the first dye. On the other hand, the content ratio of the third dye is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, per 1 part by mass of the first dye.

[0061] In a polarizing film (polarizing element) according to one embodiment, the mixing ratio of the azo compounds used is appropriately adjusted so that the transmittance falls within the range described above. The polarization characteristics of the polarizing film change depending not only on the mixing ratio of each azo compound in the polarizing film, but also on various factors such as the degree of swelling and stretching ratio of the substrate on which the azo compounds are adsorbed, the dyeing time, the dyeing temperature, the pH during dyeing, and the effect of salt. The mixing ratio of each azo compound can be determined according to the degree of swelling of the substrate, the temperature, time, pH, type of salt, salt concentration, and stretching ratio during dyeing. The first dye, the second dye, and the third dye can each be used individually or in combination of two or more.

[0062] In the dyeing process, for example, the laminate is immersed in the dyeing bath described above. The temperature of the dyeing bath is, for example, 10°C or higher, preferably 20°C or higher. On the other hand, the temperature of the dyeing bath is, for example, 80°C or lower, preferably 60°C or lower. The immersion time (dyeing time) in the dyeing process is, for example, 5 seconds or more, preferably 30 seconds or more. On the other hand, the dyeing time is, for example, 300 seconds or less, preferably 90 seconds or less. Furthermore, the method of adsorption of the dye in the dyeing process is not limited to the immersion described above. For example, the dyeing solution may be coated onto the PVA resin layer, or the dyeing solution may be sprayed onto the PVA resin layer.

[0063] C-5. Crosslinking Process In the crosslinking process, typically the laminate after the dyeing process is immersed in a crosslinking solution (crosslinking bath). Typically the crosslinking solution is an aqueous boric acid solution. The boric acid content in the crosslinking solution is, for example, 1 to 10 parts by mass per 100 parts by mass of water. The temperature of the crosslinking bath is, for example, 10°C or higher, preferably 20°C or higher. On the other hand, the temperature of the crosslinking bath is, for example, 60°C or lower, preferably 50°C or lower. The immersion time in the crosslinking process is, for example, 10 seconds or more, preferably 20 seconds or more. On the other hand, the immersion time in the crosslinking process is, for example, 200 seconds or less, preferably 60 seconds or less.

[0064] C-6. Wet stretching process In the wet stretching process, the dyed PVA resin layer (preferably the PVA resin layer after the crosslinking process) is stretched in the longitudinal direction in an aqueous boric acid solution, which serves as the stretching bath. In other words, the wet stretching process is an underwater stretching process. Stretching the PVA resin layer in an aqueous boric acid solution can suppress the dissolution of the PVA resin layer into the aqueous boric acid solution.

[0065] The stretching ratio in the wet stretching process is typically smaller than that in the dry stretching process. The stretching ratio in the wet stretching process is, for example, 3.0 times or less, preferably 2.5 times or less, and more preferably 2.0 times or less. On the other hand, the lower limit of the stretching ratio in the wet stretching process is typically 1.3 times. The product of the stretching ratio in the dry stretching process and the stretching ratio in the wet stretching process is, for example, 7.0 times or less, preferably 6.5 times or less, more preferably 5.5 times or less, and even more preferably 4.5 times or less. On the other hand, the product of the stretching ratio in the dry stretching process and the stretching ratio in the wet stretching process is, for example, 3.5 times or more, preferably 4.0 times or more. By stretching at the stretching ratios described above, the thickness of the polarizing film can be stably adjusted to the range described above.

[0066] The boric acid content in the stretching solution (boric acid aqueous solution) is, for example, 0.5 parts by mass or more, preferably 0.7 parts by mass or more, per 100 parts by mass of water. On the other hand, the boric acid content in the stretching solution is, for example, 5 parts by mass or less, preferably 3 parts by mass or less. The temperature of the stretching bath is, for example, 40°C or higher, preferably 50°C or higher. On the other hand, the temperature of the stretching bath is, for example, 85°C or lower, preferably 80°C or lower, more preferably 65°C or lower. If the temperature of the stretching bath is within this range, even if the concentration of boric acid in the stretching bath is within the above range, the dissolution of the PVA-based resin layer in the stretching bath can be stably suppressed. The immersion time in the stretching process is, for example, 15 seconds or more and 300 seconds or less.

[0067] C-7. Washing Process In the washing process, typically the laminate after the wet stretching process is immersed in a washing bath. Typically the washing bath is water. The temperature of the washing bath is, for example, 0°C or higher, preferably 10°C or higher. On the other hand, the temperature of the washing bath is, for example, 40°C or lower, preferably 30°C or lower. The immersion time in the washing process is, for example, 5 seconds or more, preferably 10 seconds or more. On the other hand, the immersion time in the washing process is, for example, 200 seconds or less, preferably 60 seconds or less.

[0068] C-8. Drying and Shrinking Process In the drying and shrinking process, the PVA resin layer after the wet stretching process (preferably after the washing process) is heated while being conveyed in the longitudinal direction. The drying and shrinking process is carried out by a heating and drying section. The heating and drying section may be a zone heating method in which the entire interior of the heating and drying section is heated, or a heated roll drying method in which the conveying rolls are heated. Preferably, both methods are used in the heating and drying section.

[0069] The internal temperature of the heating and drying section is, for example, 70°C or higher, preferably 80°C or higher. On the other hand, the internal temperature of the heating and drying section is, for example, 120°C or lower, preferably 100°C or lower. The surface temperature of the heating roll is, for example, 60°C or higher, preferably 70°C or higher. On the other hand, the surface temperature of the heating roll is, for example, 100°C or lower, preferably 80°C or lower. By drying using a heating roll, heat curling of the PVA-based resin layer (laminated) can be efficiently suppressed, and a polarizing film with excellent appearance can be efficiently manufactured.

[0070] Furthermore, during the drying shrinkage process, the PVA-based resin layer shrinks in the width direction perpendicular to the longitudinal direction. This allows the thickness of the polarizing film to be stably adjusted within the above range. The shrinkage rate of the PVA-based resin layer in the width direction during the drying shrinkage process is, for example, 2% or more, preferably 4% or more. If the shrinkage rate in the width direction is above this lower limit, the orientation of the PVA and / or organic dye can be improved, and the polarization characteristics of the polarizing film can be stably adjusted within the above range. The shrinkage rate of the PVA-based resin layer in the width direction is, for example, 10% or less, preferably 8% or less, more preferably 6% or less. If the shrinkage rate in the width direction is below this upper limit, it is possible to suppress the occurrence of appearance defects such as wrinkles in the polarizing film.

[0071] The polarizing film is manufactured as described above.

[0072] D. Polarizing Plate As shown in Figure 1, the polarizing films described in sections A to C above can be suitably applied to polarizing plates. A polarizing plate equipped with the above-described polarizing film has the same polarization characteristics as the above-described polarizing film. That is, the range of the transmittance of the polarizing plate is, for example, the same as the range of the transmittance of the above-described polarizing film. Also, the range of the degree of polarization of the polarizing plate 1 is, for example, the same as the range of the degree of polarization of the above-described polarizing film.

[0073] The polarizing plate 1 in the illustrated example comprises the polarizing film 11 described above; and a protective layer 12 provided on at least one surface of the polarizing film 11.

[0074] The protective layer 12 is provided on at least one surface of the polarizing film. The protective layer 12 may be provided on both surfaces of the polarizing film 11, or on only one surface of the polarizing film 11. In the illustrated example, the protective layer 12 is provided on only one surface of the polarizing film 11 and is located on the viewing side of the polarizing film 11.

[0075] The protective layer 12 is formed from any suitable film that can be used as a protective layer for the polarizing film 11. Specific examples of materials that make up the main component of the film include cellulosic resins such as triacetylcellulose (TAC), polyester resins, polyvinyl alcohol resins, polycarbonate resins, polyamide resins, polyimide resins, polyethersulfone resins, polysulfone resins, polystyrene resins, polynorbornene resins, polyolefin resins, cycloolefin (COP) resins, (meth)acrylic resins, acetate resins, and other transparent resins. Thermosetting resins or UV-curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone resins can also be used. In addition, glassy polymers such as siloxane polymers can also be used. Polymer films described in Japanese Patent Application Publication No. 2001-343529 (WO01 / 37007) can also be used. Note that "(meth)acrylic" refers to acrylic and / or methacrylic. In one embodiment, the protective layer 12 is made of a (meth)acrylic resin.

[0076] The thickness of the protective layer 12 is, for example, 5 mm or less, preferably 1 mm or less, more preferably 500 μm or less, even more preferably 150 μm or less, and particularly preferably 40 μm or less. On the other hand, the thickness of the protective layer 12 is, for example, 1 μm or more, preferably 5 μm or more.

[0077] A surface treatment layer may be provided on the surface of the protective layer 12 (the surface opposite to the polarizing film). Examples of surface treatment layers include a hard coat treatment layer, an anti-reflective treatment layer, an anti-sticking treatment layer, and an anti-glare treatment layer. The thickness of the surface treatment layer can be set arbitrarily and appropriately. For example, the thickness of the surface treatment layer is 1 μm to 10 μm.

[0078] The protective layer 12 typically has light transmittance. The total light transmittance of the protective layer 12 at a wavelength of 550 nm is, for example, 88% or more, preferably 90% or more. On the other hand, the upper limit of the total light transmittance of the protective layer 12 at a wavelength of 550 nm is typically 100%. Furthermore, the range of the total light transmittance of the protective layer 12 at a wavelength of 460 nm is the same as the range of the total light transmittance of the protective layer 12 at a wavelength of 550 nm described above. When the total light transmittance of the protective layer is within such a range, it is possible to suppress the influence of the protective layer on the polarization characteristics of the polarizer.

[0079] Such a protective layer 12 may be attached to the polarizing film 11 via an adhesive layer, or it may be attached to the polarizing film 11 via an adhesive layer. In one embodiment, the protective layer 12 is attached to the polarizing film 11 via an adhesive layer. The adhesive layer is made of any suitable adhesive. Examples of adhesives include UV-curing adhesives and thermosetting adhesives, with UV-curing adhesives being preferred. The thickness of the adhesive layer is, for example, 0.4 μm to 3.0 μm.

[0080] E. Optical Laminate As shown in Figure 2, in one embodiment, the polarizing plate described in Section D above is applied to an optical laminate. In the illustrated example, the optical laminate 10 comprises the polarizing plate 1 described above and a phase difference film 2.

[0081] The phase difference film 2 is located on one side of the polarizing plate 1 in the thickness direction. In the illustrated example, the phase difference film 2 is located on the opposite side of the protective layer 12 from the polarizing film 11.

[0082] The phase difference film 2 has birefringence such that one of nx, ny, and nz is not equal to the others. Typically, the phase difference film 2 has an in-plane phase difference. In one embodiment, the refractive index of the phase difference film 2 is given by nx > ny ≥ nz. A layer (film) exhibiting the refractive index characteristic nx > ny = nz is sometimes referred to as a "positive A plate". A layer (film) exhibiting the refractive index characteristic nx > ny > nz is sometimes referred to as a "negative B plate".

[0083] In one embodiment, the phase difference film 2 functions as a λ / 4 plate. The in-plane phase difference Re(550) of the phase difference film 2 is, for example, 100 nm to 200 nm, preferably 110 nm to 180 nm, more preferably 120 nm to 160 nm, and even more preferably 130 nm to 150 nm. The Nz coefficient of the phase difference film 2 is, for example, 0.9 to 2.0, preferably 0.9 to 1.5, and more preferably 0.9 to 1.2.

[0084] The angle between the absorption axis direction of the polarizing film 11 and the slow phase axis direction of the phase difference film 2 is typically 40° to 50°, preferably 42° to 48°, more preferably 44° to 46°, and particularly preferably 45°. Such an angle can impart excellent circular polarization functionality to the optical laminate.

[0085] Furthermore, the phase difference film 2 may exhibit inverse dispersion wavelength characteristics in which the phase difference value increases with the wavelength of the measured light, or it may exhibit positive wavelength dispersion characteristics in which the phase difference value decreases with the wavelength of the measured light, or it may exhibit flat wavelength dispersion characteristics in which the phase difference value hardly changes with the wavelength of the measured light.

[0086] The thickness of the phase difference film 2 is set so that desired characteristics can be obtained. The thickness of the phase difference film 2 is, for example, 1 μm or more, preferably 4 μm or more, while the thickness of the phase difference film 2 is, for example, 200 μm or less, preferably 150 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less.

[0087] The phase difference film 2 may have a single-layer structure or a laminated structure in which two or more layers are stacked.

[0088] Such a phase difference film 2 can be made of any suitable material, as long as the above-described characteristics are obtained. Examples of the phase difference film 2 include a stretched film prepared by stretching a resin film and an orientation solidified layer of a liquid crystal compound.

[0089] In one embodiment, the phase difference film 2 includes a stretched film. Examples of resin materials constituting the stretched film include norbornene-based resins, polyester carbonate-based resins, polycarbonate-based resins, cellulose-based resins, polyvinyl alcohol-based resins, and polysulfone-based resins. Such resin materials can be used individually or in combination.

[0090] Among the resin materials constituting the stretched film, polyester carbonate resins are preferred. Polyester carbonate resins include, for example, structural units derived from fluorene-based dihydroxy compounds, structural units derived from isosorbide-based dihydroxy compounds, and structural units derived from dihydroxy compounds. Examples of dihydroxy compounds include alicyclic diols, alicyclic dimethanol, di, tri, or polyethylene glycols, alkylene glycols, and spiroglycols. Dihydroxy compounds can be used alone or in combination. Polyester carbonate resins preferably include structural units derived from fluorene-based dihydroxy compounds, structural units derived from isosorbide-based dihydroxy compounds, and structural units derived from spiroglycols. Polyester carbonate resins may optionally include structural units derived from other dihydroxy compounds. Further details regarding polyester carbonate resins suitably used in the present invention are described, for example, in Japanese Patent Publication No. 2014-10291, Japanese Patent Publication No. 2014-26266, Japanese Patent Publication No. 2015-212816, Japanese Patent Publication No. 2015-212817, and Japanese Patent Publication No. 2015-212818, and such descriptions are incorporated herein by reference.

[0091] The stretched film corresponding to the phase difference film 2 is prepared by stretching a resin film composed of the above-mentioned resin material under any appropriate stretching conditions. Specifically, by appropriately selecting the type of polymer, stretching conditions (e.g., stretching temperature, stretching ratio, stretching direction), and stretching method (e.g., longitudinal uniaxial stretching), a stretched film having the above-mentioned desired optical properties (e.g., refractive index properties, in-plane phase difference, phase difference in the thickness direction) can be obtained. The thickness of such a stretched film is, for example, 10 μm to 200 μm, preferably 20 μm to 150 μm, and more preferably 30 μm to 60 μm.

[0092] In one embodiment, the phase difference film 2 includes an orientation-solidified layer of liquid crystal compound. By using a liquid crystal compound, the difference between nx and ny in the phase difference film can be made significantly larger than that of a non-liquid crystal material, so the thickness of the phase difference film required to obtain the desired in-plane phase difference can be significantly reduced. As a result, the optical laminate can be made thinner. In this specification, "orientation-solidified layer" refers to a layer in which the liquid crystal compound is oriented in a predetermined direction within the layer and this orientation state is fixed. Note that "orientation-solidified layer" is a concept that includes orientation-cured layers obtained by curing liquid crystal monomers as described later. In a phase difference film, typically, rod-shaped liquid crystal compounds are oriented in a state where they are aligned along the slow phase axis of the phase difference film (homogenous orientation).

[0093] Examples of liquid crystal compounds include liquid crystal compounds in which the liquid crystal phase is a nematic phase (nematic liquid crystals). Examples of such liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. The mechanism by which the liquid crystal properties of the liquid crystal compound are expressed can be either lyotropic or thermotropic. Liquid crystal polymers and liquid crystal monomers can be used individually or in combination.

[0094] When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer and a crosslinkable monomer. The orientation state of the liquid crystal monomer can be fixed by polymerizing or crosslinking (i.e., curing) the liquid crystal monomer. After oriented the liquid crystal monomer, the orientation state can be fixed by polymerizing or crosslinking the liquid crystal monomers together, for example. Here, polymers are formed by polymerization and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystal. Therefore, the formed phase difference film does not undergo transitions to liquid crystal phase, glass phase, and crystalline phase due to temperature changes, which is characteristic of liquid crystal compounds. As a result, the phase difference film has extremely excellent stability that is not affected by temperature changes.

[0095] Any suitable liquid crystal monomer can be used as the liquid crystal monomer. For example, polymerizable mesogenic compounds described in JP 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445 can be used. Specific examples of such polymerizable mesogenic compounds include, for example, BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Silicon-CC3767. Among liquid crystal monomers, nematic liquid crystal monomers are preferred.

[0096] In one embodiment, the orientation-solidified layer of the liquid crystal compound is formed by applying an orientation treatment to the surface of any suitable substrate, coating the surface with a coating liquid containing the liquid crystal compound to orient the liquid crystal compound in a direction corresponding to the orientation treatment, and fixing the orientation state. Specific examples of liquid crystal compounds and details of the method for forming the orientation-solidified layer are described in Japanese Patent Application Publication No. 2006-163343. The description in that publication is incorporated herein by reference. The thickness of such an orientation-solidified layer of the liquid crystal compound is, for example, 0.5 μm to 20.0 μm, preferably 1.0 μm to 10.0 μm, and more preferably 3.0 μm to 8.0 μm.

[0097] In one embodiment, the phase difference film 2 is attached to the polarizing plate 1 via an adhesive layer 3. That is, the optical laminate 10 further comprises an adhesive layer 3 located between the phase difference film 2 and the polarizing plate 1. In the illustrated example, the adhesive layer 3 is in contact with the phase difference film 2 and the polarizing film 11. The adhesive layer 3 may be an adhesive layer composed of any suitable adhesive, or an adhesive layer composed of any suitable adhesive. If the adhesive layer 3 is an adhesive layer, it is typically composed of a (meth)acrylic adhesive. The thickness of the adhesive layer is, for example, 3.5 μm to 35 μm. If the adhesive layer 3 is an adhesive layer, it is typically composed of an ultraviolet-curing adhesive and / or a thermosetting adhesive. The thickness of the adhesive layer is, for example, 0.4 μm to 3.0 μm.

[0098] In the illustrated example, the optical laminate 10 further includes an adhesive layer 4 located on the side opposite to the polarizing plate 1 with respect to the retardation film 2. In the illustrated example, the adhesive layer 4 is provided on the surface of the retardation film 2 on the side opposite to the polarizing plate 1. The adhesive layer 4 is composed of any suitable adhesive, and typically is composed of a (meth)acrylic adhesive. The thickness of the adhesive layer 4 is, for example, 3.5 μm to 35 μm.

[0099] The thickness of such an optical laminate 10 is, for example, 120 μm or less, preferably 100 μm or less, more preferably 80 μm or less. On the other hand, the lower limit of the thickness of the optical laminate 10 is typically 30 μm.

[0100] F. Image Display Device Each of the polarizing film described in Items A to C above, the polarizing plate described in Item D above, and the optical laminate described in Item E above can be applied to any suitable industrial product. Such industrial products include, for example, image display devices and polarized sunglasses, and preferably image display devices. Representative examples of image display devices include liquid crystal display devices and organic EL (electroluminescence) display devices.

[0101] As shown in FIG. 3, in one embodiment, the polarizing film 11 is applied to the organic EL display device 100. More specifically, the organic EL display device 100 includes an optical laminate 10 including the polarizing film 11 and an organic EL element 5. The organic EL element 5 is located on the side opposite to the polarizing plate 1 with respect to the retardation film 2. In the illustrated example, the optical laminate 10 is attached to the organic EL element 5 by the adhesive layer 4.

[0102] The organic EL element 5 has any suitable configuration. The organic EL element 5 includes any suitable light-emitting material according to the color conversion method. Examples of the light-emitting material include a blue light-emitting material, a red light-emitting material, a green light-emitting material, and a white light-emitting material. The light-emitting materials can be used alone or in combination according to the color conversion method.

[0103] The reflectance of the organic EL element 5 is, for example, 40% or less, preferably 35% or less, and more preferably 20% or less. On the other hand, the lower limit of the reflectance of the organic EL element 5 is typically 5%. If an organic EL display device has such an organic EL element, the reflectance of the organic EL display device can be sufficiently reduced even if the degree of polarization in the polarizing film (polarizing plate) is within the above range.

[0104] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement methods for each characteristic are as follows.

[0105] (1) Thickness measurement The thickness of the polarizing films obtained in the examples and comparative examples was measured using a film tester thickness measuring instrument (HKT-1202 manufactured by Fujiwork Corporation). The results are shown in Table 2.

[0106] (2) Measurement of Orientation Function In the examples and comparative examples, for each of the PVA resin layer (before wet stretching) and the polarizing film, an ATR measurement was performed using a Fourier transform infrared spectrophotometer (FT-IR) (manufactured by Perkin Elmer, trade name: "Frontier"), with polarized infrared light as the measurement light. The surfaces of these materials (specifically, the surface of the PVA resin layer opposite to the resin substrate, or the peeled surface of the resin substrate in the polarizing film) were measured. Germanium crystallites were used, and the incident angle of the measurement light was set to 45°. The orientation function was calculated using the following procedure. The incident polarized infrared light (measurement light) was polarized to vibrate parallel to the surface to which the germanium crystal sample was in contact (s-polarization), and the absorbance spectra were measured with the stretching direction of the polarizing film positioned perpendicular (⊥) and parallel ( / / ) to the polarization direction of the measurement light. From the obtained absorbance spectra, (3330 cm⁻¹) was calculated. －１ (Strength) was referenced (2941 cm) －１ The intensity I was calculated. I⊥ is obtained from the absorbance spectrum obtained when the stretching direction of the polarizing film is positioned perpendicular (⊥) to the polarization direction of the measured light (2941 cm⁻¹). －１ strength) / (3330cm －１ Intensity) is also obtained from the absorbance spectrum obtained when the stretching direction is placed parallel ( / / ) to the polarization direction of the measured light (2941 cm).－１ strength) / (3330cm －１ Strength) is the strength. Here, (2941 cm －１ The intensity is at 2770 cm⁻¹, which is the bottom of the absorbance spectrum. －１ and 2990cm －１ 2941 cm with baseline －１ This is the absorbance, (3330 cm) －１ The strength is 2990 cm. －１ and 3650cm －１ 3330 cm with baseline －１ This is the absorbance. Using the obtained I⊥ and I / / , the orientation function f was calculated according to the following equation (A). The results are shown in Table 2. f = (3 < cos ２ θ>-1) / 2=(1-D) / [c(2D+1)]...(A) However, c=(3cos ２ β-1) / 2, as shown above, is 2941 cm －１ When using this, β = 90° ⇒ f = -2 × (1 - D) / (2D + 1). θ: Angle of the molecular chain with respect to the stretching direction β: Angle of the transition dipole moment with respect to the molecular chain axis D = (I⊥) / (I / / ) I⊥: Absorption intensity when the polarization direction of the measured light and the stretching direction are perpendicular I / / : Absorption intensity when the polarization direction of the measured light and the stretching direction are parallel Note that when f = 1, it is perfectly oriented, and when f = 0, it is random. Also, 2941 cm －１ The peak is the main chain (-CH) of the PVA resin. ２ It is said to be absorption caused by vibrations of -). Also, 3330 cm －１ The peak is said to be due to absorption caused by the vibration of hydroxyl groups in PVA resins.

[0107] (3) Measurement of Single-Piece Transmittance and Polarization Degree The single-piece transmittance (Ts: initial transmittance), parallel transmittance (Tp), and orthogonal transmittance (Tc) of the polarizers obtained in the examples and comparative examples were measured in the wavelength range of 380 nm to 780 nm using a UV-Vis spectrophotometer (manufactured by JASCO Corporation, product name "V7100"). The above Ts, Tp, and Tc are Y values ​​that were measured using a 2-degree field of view (C light source) according to JIS Z8701 and corrected for luminous efficiency. Furthermore, the polarization degree (P) of the polarizer was calculated using the following formula (B). Polarization degree (P) (%) = {(Tp - Tc) / (Tp + Tc)} 1 / 2 × 100 ... (B) The results are shown in Table 2 and Figure 4. Note that the single-piece transmittance and polarization degree of the polarizer are substantially the same as those of the polarizing film.

[0108] (4) Orthogonal hue a ＊ and b ＊ The orthogonal hue a of the polarizing plates obtained in the measurement examples and comparative examples. ＊ and b ＊ The wavelengths were measured in the range of 380 nm to 780 nm using a UV-Vis spectrophotometer (manufactured by JASCO Corporation, product name "V7100"). The results are shown in Table 3. Note that the orthogonal hues of the polarizing plate and the orthogonal hues of the polarizing film are substantially the same.

[0109] (5) Measurement of reflectance The optical laminates obtained in the examples and comparative examples were attached to a first aluminum reflector having a reflectance of 94% for light with a wavelength of 550 nm, or a second aluminum reflector having a reflectance of 13.5% for light with a wavelength of 550 nm, using an adhesive layer. Then, using a spectrophotometer (Konica Minolta "CM-2600d"), light with a wavelength of 550 nm was irradiated from the polarizer side, and the reflectance (initial reflectance) of the optical laminate was measured using the SCI method. The results are shown in Table 3.

[0110] (6) Heat Durability Test (Edge Decolorization) The optical laminates obtained in the examples and comparative examples were bonded to glass and left to stand for 500 hours in an environment of 80°C. After that, the reflectance of the optical laminate after the heat durability test was measured in the same manner as in "(5) Measurement of Reflectance" above. The results are shown in Table 3. In addition, the optical laminate after the heat durability test was observed using an optical microscope to see whether decolorization had occurred at both ends in the absorption axis direction of the polarizing film. The results are shown in Table 2. Furthermore, the transmittance (Ts) of the polarizer contained in the optical laminate after the heat durability test was measured in the same manner as in "(3) Measurement of Single Transmittance and Polarization Degree" above, and the rate of change in the transmittance of the polarizer at a wavelength of 550 nm (= (transmittance after heat durability test) / (transmittance before heat durability test) × 100) was calculated. The results are shown in Table 2. Furthermore, the orthogonal hue a of the polarizer contained in the optical laminate after the heat durability test ＊ and b ＊ The above "(4) orthogonal hue a ＊ and b ＊ The measurements were taken in the same manner as described in "Measurement of...". The results are shown in Table 2.

[0111] (7) Humidification Durability Test (Edge Decolorization) The optical laminates obtained in the Examples and Comparative Examples were bonded to glass and left to stand for 500 hours in an environment of 65°C and 90% RH (relative humidity). After that, the reflectance of the optical laminate after the humidity durability test was measured in the same manner as in "(5) Measurement of Reflectance" above. The results are shown in Table 3. In addition, the optical laminate after the humidity durability test was observed using an optical microscope to see whether decolorization had occurred at both ends in the absorption axis direction of the polarizing film. The results are shown in Table 2. Furthermore, the transmittance (Ts) of the polarizer contained in the optical laminate after the humidity durability test was measured in the same manner as in "(3) Measurement of Single Transmittance and Polarization Degree" above, and the rate of change in the transmittance of the polarizer at a wavelength of 550 nm (= (transmittance after humidity durability test) / (transmittance before humidity durability test) × 100) was calculated. The results are shown in Table 2. Furthermore, the orthogonal hue a of the polarizer contained in the optical laminate after the humidity durability test ＊ and b ＊ The above "(4) orthogonal hue a ＊ and b ＊The measurements were taken in the same manner as described in "Measurement of...". The results are shown in Table 2.

[0112] <<Production Example 1>> <First Phase Difference Film: Stretched Film> A batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and reflux condensers controlled to 100°C was used to inject 29.60 parts by mass (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane, 29.21 parts by mass (0.200 mol) of isosorbide (ISB), 42.28 parts by mass (0.139 mol) of spiroglycol (SPG), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19 × 10⁻¹⁶ calcium acetate monohydrate as a catalyst. －２ Parts by mass (6.78×10 －５A mol of phenol was added. After purging the reactor with reduced pressure using nitrogen, the reactor was heated with a heat transfer medium, and stirring was started when the internal temperature reached 100°C. Forty minutes after the start of heating, the internal temperature was raised to 220°C, and while controlling the pressure to maintain this temperature, the pressure was reduced to 13.3 kPa 90 minutes after reaching 220°C. The phenol vapor produced as a by-product of the polymerization reaction was led to a reflux condenser at 100°C, and the monomer components contained in small amounts in the phenol vapor were returned to the reactor. The uncondensed phenol vapor was led to a condenser at 45°C and recovered. Nitrogen was introduced into the first reactor to restore the pressure to atmospheric pressure, and then the oligomerized reaction solution in the first reactor was transferred to the second reactor. Next, heating and depressurization in the second reactor were started, and the internal temperature reached 240°C and the pressure 0.2 kPa in 50 minutes. Polymerization was then allowed to proceed until the predetermined stirring power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor to restore pressure, and the resulting polyester carbonate resin was extruded into water. The strands were then cut to obtain pellets. The obtained polyester carbonate resin (pellets) was vacuum-dried at 80°C for 5 hours. A long resin film with a thickness of 130 μm was then produced using a film-making apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder setting temperature: 250°C), a T-die (width 200 mm, setting temperature: 250°C), a chill roll (setting temperature: 120-130°C), and a winding machine. The obtained long resin film was stretched 2.8 times at 143°C to obtain a first phase difference film (positive A plate) with a thickness of 46 μm. The first phase difference film had a refractive index characteristic of nx > ny = nz, and its in-plane phase difference Re(550) was 147 nm.

[0113] <<Manufacturing Example 2>> <Second Phase Difference Film: Oriented and Solidified Layer of Liquid Crystal Compound> A liquid crystal composition (coating solution) was prepared by dissolving 10 parts by mass of polymerizable liquid crystal exhibiting a nematic liquid crystal phase (BASF: trade name "Paliocolor LC242") and 3 parts by mass of a photopolymerization initiator for the polymerizable liquid crystal compound (IGM Resins B.V., trade name Omnirad907) in 40 parts by mass of toluene. The surface of a polyethylene terephthalate (PET) film (thickness 38 μm) was rubbed with a rubbing cloth to perform an orientation treatment. The direction of the orientation treatment was set to be 45° with respect to the direction of the absorption axis of the polarizing film when bonded to a polarizing plate. The liquid crystal coating solution was applied to this orientation-treated surface using a bar coater and the liquid crystal compound was oriented by heating and drying at 90°C for 2 minutes. The liquid crystal layer thus formed was heated using a metal halide lamp at a rate of 1 mJ / cm². ２ By irradiating the liquid crystal layer with light and curing it, an orientation-solidified layer of liquid crystal compound, which serves as a second phase difference film, was formed on the PET film. The thickness of the orientation-solidified layer of liquid crystal compound was 5 μm. The orientation-solidified layer of liquid crystal compound had a refractive index characteristic of nx > ny = nz, and its in-plane phase difference Re(550) was 147 nm.

[0114] <<Example 1>> As a thermoplastic resin substrate, an amorphous isophthalic copolymer polyethylene terephthalate film (thickness: 100 μm) with a long length and a Tg of approximately 75°C was used, and one side of the resin substrate was subjected to corona treatment. A PVA-based resin was prepared by dissolving a PVA-based resin (coating solution) prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosephymer") in a 9:1 ratio in water. The PVA-based resin (coating solution) was applied to the corona-treated surface of the resin substrate and dried at 60°C to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate. Next, the laminate was uniaxially stretched in the longitudinal direction (longitudinal direction) in an oven at 130°C at the dry stretching ratio shown in Table 2 (dry stretching process). Subsequently, the laminate was immersed in a swelling bath (pure water) at a liquid temperature of 40°C for 60 seconds (swelling step). Next, the laminate was immersed in a dyeing bath at a liquid temperature of 52°C for 60 seconds (dyeing step). The dyeing bath was prepared by dissolving combination example 1, namely the first dye (compound example 140), the second dye A (compound example 269), the second dye B (compound example 396), and the third dye (compound example 454) in water. In the dyeing bath, the concentration of the first dye was 0.04% by mass, the concentration of the second dye A was 0.02% by mass, the concentration of the second dye B was 0.02% by mass, and the concentration of the third dye was 0.02% by mass. Subsequently, the laminate was immersed in a stretching bath at a liquid temperature of 60°C (a boric acid aqueous solution obtained by mixing 4 parts by mass of boric acid with 100 parts by mass of water) and uniaxially stretched in the longitudinal direction between rolls with different peripheral speeds at the wet stretching ratios shown in Table 2 (wet stretching process). The total stretching ratios for the dry stretching process and the wet stretching process are also shown in Table 2. Next, the laminate was immersed in a washing bath (water) at a liquid temperature of 20°C (washing treatment). Then, the laminate was dried in an oven maintained at approximately 90°C while being brought into contact with a heated SUS roll whose surface temperature was maintained at approximately 75°C (drying shrinkage process). This caused the PVA-based resin layer on the resin substrate to shrink in the width direction, forming a polarizing film. The thickness of the polarizing film is shown in Table 2. The obtained polarizing film was then subjected to the "(2) Measurement of Orientation Function" described above.

[0115] Next, a 20 μm thick acrylic resin film manufactured by Toyo Kohan Co., Ltd. was attached to the surface of the polarizing film (the side opposite to the resin substrate) as a protective layer, via a UV-curable adhesive layer (1 μm thick). The total light transmittance of the acrylic resin film at a wavelength of 550 nm was 92.1%. Next, the resin substrate was peeled off to obtain a polarizing plate having a protective layer / polarizing film configuration. The obtained polarizing plate was subjected to the measurements of "(3) Single-component transmittance and polarization degree" and "(4) Orthogonal hue a" described above. ＊ and b ＊ It was subjected to "measurement".

[0116] <<Example 2>> A polarizing plate was obtained in the same manner as in Example 1, except that the dye concentration of the dyeing bath was adjusted so that the transmittance of the polarizing film alone was 54.3%.

[0117] <<Example 3>> A polarizing plate was obtained in the same manner as in Example 1, except that the dye concentration of the dyeing bath was adjusted so that the transmittance of the polarizing film alone was 61.8%.

[0118] <<Example 4>> The wet stretching ratio was changed to 2.30 times, and the dye concentration of the dyeing bath was adjusted so that the transmittance of the polarizing film alone was 45.6%, and the orthogonal hue a of the polarizing film ＊ b ＊ A polarizing plate was obtained in the same manner as in Example 1, except that the values ​​were adjusted to those listed in Table 2.

[0119] <<Example 5>> The dye concentration of the dye bath was adjusted so that the transmittance of the polarizing film alone was 50.2%, and the orthogonal hue a of the polarizing film was set. ＊ b ＊ A polarizing plate was obtained in the same manner as in Example 1, except that the values ​​were adjusted to those listed in Table 2.

[0120] <<Example 6>> The wet stretching ratio was changed to 2.30 times, and the dye concentration of the dyeing bath was adjusted so that the transmittance of the polarizing film alone was 55.0%, and the orthogonal hue a of the polarizing film ＊ b ＊ A polarizing plate was obtained in the same manner as in Example 1, except that the values ​​were adjusted to those listed in Table 2.

[0121] <<Example 7>> The dye concentration of the dye bath was adjusted so that the transmittance of the polarizing film alone was 68.3%, and the orthogonal hue a of the polarizing film was set. ＊ b ＊ A polarizing plate was obtained in the same manner as in Example 1, except that the values ​​were adjusted to those listed in Table 2.

[0122] <<Example 8>> The wet stretching ratio was changed to 2.30 times, and the dye concentration of the dye bath was adjusted so that the transmittance of the polarizing film alone was 72.6%, and the orthogonal hue a of the polarizing film ＊ b ＊ A polarizing plate was obtained in the same manner as in Example 1, except that the values ​​were adjusted to those listed in Table 2.

[0123] <<Comparative Example 1>> A polarizing plate was obtained in the same manner as in Example 4, except that iodine and potassium iodide were dissolved in water to prepare the dyeing bath instead of the organic dyes (first dye, second dye, and third dye). The mass ratio of iodine to potassium iodide in the dyeing bath was 1:7, and the iodine concentration in the dyeing bath was 0.2% by mass.

[0124] <<Example 9>> The first phase difference film of Manufacturing Example 1 was attached to the peelable surface (the side opposite to the protective layer) of the resin substrate in the polarizing film of the polarizing plate obtained in Example 1, via a (meth)acrylic adhesive layer (thickness 5 μm). Subsequently, a (meth)acrylic adhesive layer (thickness 15 μm) was formed on the first phase difference film. This resulted in an optical laminate having the configuration of protective layer / polarizing film / (meth)acrylic adhesive layer / first phase difference film / (meth)acrylic adhesive layer. The thickness of the optical laminate is shown in Table 3. The obtained optical laminate was subjected to the above-described "(5) Measurement of reflectivity", "(6) Heat durability test", and "(7) Humidification durability test".

[0125] <<Example 10>> An optical laminate was obtained in the same manner as in Example 9, except that the polarizing plate obtained in Example 1 was replaced with the polarizing plate obtained in Example 2.

[0126] <<Example 11>> An optical laminate was obtained in the same manner as in Example 9, except that the polarizing plate obtained in Example 1 was replaced with the polarizing plate obtained in Example 3.

[0127] <<Example 12>> In Example 1, a second phase difference film (orientation solidification layer of liquid crystal compound) from Manufacturing Example 2 was attached to the peelable surface (the side opposite to the protective layer) of the resin substrate in the polarizing film of the polarizing plate obtained in Example 1, via a (meth)acrylic adhesive layer (thickness 5 μm). Subsequently, a (meth)acrylic adhesive layer (thickness 15 μm) was formed on the second phase difference film. This resulted in an optical laminate having the configuration of protective layer / polarizing film / (meth)acrylic adhesive layer / second phase difference film / (meth)acrylic adhesive layer.

[0128] <<Example 13>> An optical laminate was obtained in the same manner as in Example 12, except that the polarizing plate obtained in Example 1 was replaced with the polarizing plate obtained in Example 2.

[0129] <<Example 14>> An optical laminate was obtained in the same manner as in Example 12, except that the polarizing plate obtained in Example 1 was replaced with the polarizing plate obtained in Example 3.

[0130] <<Comparative Example 2>> An optical laminate was obtained in the same manner as in Example 9, except that the polarizing plate obtained in Example 1 was replaced with the polarizing plate obtained in Comparative Example 1.

[0131] <<Reference Example 1>> A black adhesive layer was formed on one side of a 20 μm thick acrylic resin film manufactured by Toyo Kohan Co., Ltd. as follows. <Preparation of Acrylic Polymer P> In a reaction vessel equipped with a reflux condenser, a nitrogen inlet tube, a thermometer, and a stirrer, a mixture containing 63 parts by mass of 2-ethylhexyl acrylate (2EHA), 9 parts by mass of methyl methacrylate (MMA), 13 parts by mass of 2-hydroxyethyl acrylate (2HEA), 15 parts by mass of N-vinyl-2-pyrrolidone (NVP), 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator, and 233 parts by mass of ethyl acetate as a solvent was stirred at 60°C for 7 hours under a nitrogen atmosphere (polymerization reaction). This yielded a polymer solution S containing acrylic polymer P. <Preparation of Adhesive Composition> To a polymer solution S, 0.25 parts by mass (solid content equivalent) of isocyanate crosslinking agent (product name "Takenate D110N", manufactured by Mitsui Chemicals, Inc.) and 0.25 parts by mass (solid content equivalent) of black dye (product name "Valifast Black 3810", 1% by mass ethyl acetate solution, manufactured by Orient Chemical Industry Co., Ltd.) as a black component were added and mixed to prepare an adhesive composition. <Preparation of Adhesive Sheet> First, the adhesive composition was applied to the release-treated surface of a 38 μm thick first release liner (product name "MRF#38", polyester film, manufactured by Mitsubishi Chemical Corporation), which had one side already been peeled, to form a coating film. Next, this coating film was dried by heating at 132°C for 3 minutes. This formed an adhesive layer with a thickness of 25 μm on the first release liner. Next, the release-treated side of a 38 μm thick second release liner (product name "MRE#38", polyester film, manufactured by Mitsubishi Chemical Corporation), which had one side of the release treatment applied, was bonded to the adhesive layer on the first release liner. After that, the sheet was aged at 60°C for 24 hours to promote the cross-linking reaction in the adhesive layer. In this way, a black adhesive sheet (25 μm thick) with a release liner was prepared as the adhesive sheet for Reference Example 1.<Fabrication of laminate> After peeling the second release liner from the adhesive sheet in the adhesive sheet with a release liner (first release liner / adhesive sheet / second release liner), the adhesive sheet exposed by the peeling was bonded to one side of an acrylic resin film with a thickness of 20 μm manufactured by Toyo Kohan Co., Ltd., and then the first release liner was peeled off to fabricate a laminate (protective layer / black adhesive). Thus, a laminate was obtained. The obtained laminate was subjected to the above-mentioned "(3) Measurement of single transmittance and degree of polarization", "(5) Measurement of reflectance", "(6) Heat durability test", and "(7) Humidity durability test". The results are shown in Tables 2 and 3.

[0132] <<Reference Example 2>> A laminate was obtained in the same manner as in Reference Example 1, except that 0.21 parts by mass (in terms of solid content) of a black dye (product name "Valifast Black 3810", 1 mass% ethyl acetate solution, manufactured by Orient Chemical Industries Co., Ltd.) was added to the polymer solution S and mixed to adjust the transmittance to 57.2%.

[0133]

[0134]

[0135] [Evaluation] As is clear from Table 2, when the polarizing film contains a PVA-based resin and an organic dye, and the organic dye contains a first dye which is an azo compound having a ureido skeleton represented by the above formula (1) or a salt thereof, even if the polarizing film is thinned to a thickness of 10 μm or less and the single transmittance of the polarizing film is adjusted to 45% or more, it can be seen that in the polarizing film, uneven coloring can be suppressed, and decoloring in each of the heating environment and the humidifying environment can be suppressed. Therefore, when the optical laminate provided with the polarizing film obtained in the example is applied to an image display device, it can be seen that in the image display device, display unevenness can be suppressed, and the reflectance can be stably reduced regardless of the usage environment (see Table 3). In particular, from the comparison between the reference example and the example, it can be seen that even when the image display device is exposed to a high-temperature environment, the reflectance can be maintained significantly smaller than that of the black adhesive (OBA).

[0136] The polarizing film of the present invention can be used in image display devices (typically liquid crystal display devices and organic EL display devices), and is particularly suitable for use in organic EL display devices.

[0137] 1 Polarizing film 11 Polarizing film 12 Protective layer 2 Phase difference film 3 Adhesive layer 4 Adhesive layer 5 Organic EL element 10 Optical laminate 100 Organic EL display device

Claims

A polarizing film containing a polyvinyl alcohol-based resin and an organic dye, The thickness of the polarizing film is 10 μm or less. The transmittance of the polarizing film alone is 45% or more. The polarization degree of the polarizing film is 95% or less. The aforementioned organic dye comprises a first dye which is an azo compound having a ureid skeleton represented by the following formula (1) or a salt thereof, in a polarizing film: In formula (1), Ay １ and Ay ２ are each independently a naphthyl group which may have a substituent or a phenyl group which may have a substituent, s and t are each independently 0 or 1, and either s or t is 1, Ry １ to Ry ８ each independently represent a hydrogen atom or a substituent: The phenyl group which may have the above-mentioned substituent is a phenyl group having at least one or more substituents selected from the group consisting of a sulfo group, a carboxy group, an alkoxy group having 1 to 4 carbon atoms and having a sulfo group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a nitro group, an amino group, an alkyl-substituted amino group having 1 to 4 carbon atoms, and an alkyl-substituted acylamino group having 1 to 4 carbon atoms. The naphthyl group which may have a substituent is a naphthyl group which may have a substituent selected from the group consisting of a hydroxy group, an alkoxy group having 1 to 4 carbon atoms and having a sulfo group, and a sulfo group: Ry １ , Ry ２ , Ry ７ , Ry ８ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and Ry ３ to Ry ６ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms and having a sulfo group. 　 The aforementioned organic dye is A second dye which is an azo compound or a salt thereof represented by the following formula (2), A polarizing film according to claim 1, further comprising a third dye which is an azo compound represented by the following formula (3) or a salt thereof: In formula (2), Ar １１ Rr represents a substituted phenyl group or a substituted naphthyl group. １１ ~Rr １６ Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C1-C4 alkoxy group having a sulfo group, and Xr １１ represents an amino group which may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a benzoyl group which may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a phenylamino group which may have substituents selected from the group consisting of C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a benzoylamino group which may have substituents selected from the group consisting of C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups; a phenylazo group which may have substituents selected from the group consisting of C1-C4 alkoxy groups, sulfo groups, hydroxyl groups, amino groups, and substituted amino groups; or a naphthotriazole group which may have substituents selected from the group consisting of C1-C4 alkyl groups, C1-C4 alkoxy groups, sulfo groups, amino groups, and substituted amino groups, and m1 and n1 each independently represent 0 or 1, and when m1 and n1 are 1, Rr １５ and Rr １６ Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group, and when m1 and n1 are 0, Rr １１ and Rr １２ Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group having a sulfo group: In equation (3), A is Ar in equation (2). １１ Similarly, or the following general formula (4) (In formula (4), A １ (This represents a nitro group or an amino group.) A substituent represented by R １ ~R ４ , R ６ Rr in the above formula (2) １１ ~Rr １４ Similarly, X is Xr of equation (2) above. １１ This is similar to the previous case, where m and n are either 0 or 1. 　 The content of the first dye in the organic dye is 0.01% by mass to 50% by mass. The content ratio of the second dye is 0.01 parts by mass to 10 parts by mass per 1 part by mass of the first dye. The polarizing film according to claim 2, wherein the content ratio of the third dye is 0.01 parts by mass to 5 parts by mass per 1 part by mass of the first dye. In the CIE-Lab color system, orthogonal hue a ＊ The following equation (I) is satisfied, and the orthogonal hue b ＊ The polarizing film according to claim 1 or 2 satisfies the following formula (II): 0.5 ≤ orthogonal hue a ＊ ≦5.5...(I) -20 ≤ orthogonal hue b ＊ ≦2.5...(II). 　 The polarizing film according to claim 1 or 2, wherein the thickness of the polarizing film is 6 μm or less. 　 The polarizing film according to claim 1 or 2, wherein the transmittance of the polarizing film alone at a wavelength of 460 nm is 44% or more. 　 The polarizing film according to claim 1 or 2, wherein the transmittance of the polarizing film alone at a wavelength of 460 nm is 0.9 times or more than the transmittance of the polarizing film alone at a wavelength of 550 nm. 　 A polarizing plate comprising the polarizing film described in claim 1, An optical laminate comprising a phase difference film located on one side in the thickness direction of the polarizing plate. 　 The optical laminate according to claim 8, wherein the thickness is 80 μm or less. 　 The optical laminate according to claim 8 or 9, The system comprises an organic EL element located on the opposite side of the polarizing plate from the phase difference film, An organic EL display device in which the reflectance of the organic EL element is 20% or less.

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