Polarization plate with retardation layer

Abstract

To provide a polarization plate with a retardation layer that includes a retardation layer having reverse dispersion characteristics and can suppress occurrence of poor appearance under high temperature high humidity environment.SOLUTION: A polarization plate with a retardation layer includes a polarizer and a retardation layer containing cellulose-based resin and ester-based resin in this order. Re(450) / Re(550) of the retardation layer is 0 to 1. Re(550) of the retardation layer is 100 nm to 200 nm. An angle defined by an absorption axis direction of the polarizer and a slow phase axis direction of the retardation layer is 40° to 50° or 130°to 140°. In the retardation layer, a nanophase separated structure is formed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a polarizing plate with a retardation layer.

Background Art

[0002] In image display devices, various optical laminate bodies combining a polarizer and an optical compensation film are generally used to compensate for optical characteristics suitable for the application. As such an optical laminate body, for example, a polarizing plate with a retardation layer including a polarizer and a retardation layer which is a λ / 4 plate and formed from a modified polyester carbonate resin in this order has been proposed (see, for example, Patent Document 1). In recent years, the usage environments of image display devices have diversified, and durability under high-temperature and high-humidity environments may be required. Regarding the durability under such high-temperature and high-humidity environments, there is room for improvement in the polarizing plate with a retardation layer described in Patent Document 1. In the polarizing plate with a retardation layer described in Patent Document 1, there is a risk of appearance defects such as cracks and peeling of the retardation layer especially under high-temperature and high-humidity environments.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention has been made to solve the above conventional problems, and its main object is to provide a polarizing plate with a retardation layer including a retardation layer having reverse dispersion characteristics, which can suppress the occurrence of appearance defects under high-temperature and high-humidity environments.

Means for Solving the Problems

[0005] [1] A polarizing plate with a phase difference layer according to an embodiment of the present invention comprises a polarizer and a phase difference layer containing a cellulose resin and an ester resin, in that order. The Re(450) / Re(550) of the phase difference layer is 0 to 1, and the Re(550) of the phase difference layer is 100 nm to 200 nm. The angle between the absorption axis direction of the polarizer and the slow phase axis direction of the phase difference layer is 40° to 50°, or 130° to 140°. A nanophase separation structure is formed in the phase difference layer. [2] One embodiment is a polarizing plate with a phase difference layer as described in item [1] above, wherein the cellulose resin has the constituent units shown in the following formula (1). [ka] (In formula (1), each of R1 to R3 represents a hydrogen atom or a substituent having 1 to 12 carbon atoms). [3] One embodiment is a polarizing plate with a phase difference layer according to item [1] or [2] above, wherein the ester resin has a constituent unit shown in formula (2) below and a constituent unit shown in formula (3) below. [ka] (In formula (2), R4 represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms; R 5a R represents one selected from an alkyl group having 1 to 12 carbon atoms, a nitro group, a bromo group, an iodo group, a cyano group, a chloro group, a sulfonic acid group, a carboxylic acid group, a fluoro group, or a thiol group; R 5b R6 represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms; R6 represents a species selected from a hydrogen atom, a nitro group, a bromo group, an iodo group, a cyano group, a chloro group, a sulfonic acid group, a carboxylic acid group, a fluoro group, a phenyl group, a thiol group, an amide group, an amino group, a hydroxyl group, an alkoxy group having 1 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms. [ka] (In formula (3), R7 represents a five-membered heterocyclic residue or a six-membered heterocyclic residue containing one or more nitrogen or oxygen atoms as heteroatoms (the five-membered heterocyclic residue and the six-membered heterocyclic residue may form a fused ring structure with other cyclic structures).) [4] One embodiment is the polarizing plate with a phase difference layer according to item [3] above, wherein the ester resin further comprises the constituent units shown in the following formula (4). [ka] (In formula (4), R8 and R9 each represent one selected from a hydrogen atom, a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 3 to 12 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms.) [5] One embodiment is a polarizing plate with a phase difference layer according to any of the above items [1] to [4], wherein the content of the cellulose resin exceeds 50% by mass when the total amount of the cellulose resin and the ester resin is 100% by mass. [6] One embodiment is a polarizing plate with a phase difference layer according to any of the above items [1] to [5], wherein the phase difference layer is a stretched film obtained by stretching a resin film containing a cellulose resin and an ester resin, and the number of MITs in a direction perpendicular to the stretching direction of the stretched film is 300 or more. [Effects of the Invention]

[0006] According to embodiments of the present invention, a polarizing plate with a phase difference layer having inverse dispersion characteristics can be realized, in which the occurrence of appearance defects in high temperature and high humidity environments is suppressed. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic cross-sectional view of a polarizing plate with a phase difference layer according to one embodiment of the present invention. [Modes for carrying out the invention]

[0008] The following describes representative embodiments of the present invention, but the present invention is not limited to these embodiments.

[0009] (Definitions of terms and symbols) The definitions of terms and symbols used in this specification are as follows: (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction where the refractive index is maximum in the plane (i.e., the slow phase axis direction), "ny" is the refractive index in the direction perpendicular to the slow phase axis in the plane (i.e., the fast phase axis direction), 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 using the formula: Re(λ) = (nx - ny) × d, where d (nm) is the thickness of the layer (film). (3)Angle In this specification, when an angle is mentioned, unless otherwise specified, it includes angles in both clockwise and counterclockwise directions. (4) In-plane birefringence (Δn) "Δn(λ)" is the in-plane birefringence measured with light of wavelength λnm at 23°C. For example, "Δn(550)" is the in-plane birefringence measured with light of wavelength 550nm at 23°C. The in-plane birefringence (Δn) can be calculated using the formula: Δn = nx - ny. (5) 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 wavelength 550nm at 23°C. Rth(λ) can be calculated using the formula: Rth(λ) = (nx - nz) × d, where d (nm) is the thickness of the layer (film). (6) Nz coefficient The Nz coefficient is calculated using the formula Nz = Rth / Re.

[0010] A. Overall configuration of a polarizing plate with a phase difference layer Figure 1 is a schematic cross-sectional view of a polarizing plate with a phase difference layer according to one embodiment of the present invention. The polarizing plate with a phase difference layer 100 in the illustrated example comprises, in this order: a polarizing plate 10 containing a polarizer 11; and a phase difference layer 20 containing a cellulose resin and an ester resin. The Re(450) / Re(550) of the phase difference layer 20 is 0 to 1, and also, for example, 0.60 to 0.99, and also, for example, 0.70 to 0.95, and also, for example, 0.70 to 0.90. The Re(550) of the phase difference layer 20 is 100 nm to 200 nm, and also, for example, 120 nm to 160 nm, and also, for example, 130 nm to 150 nm. The phase difference layer 20 typically functions as a λ / 4 plate. The angle between the absorption axis direction of the polarizer 11 and the slow phase axis direction of the phase difference layer 20 is 40° to 50°, preferably 42° to 48°, more preferably 44° to 46°, and even more preferably about 45°; or 130° to 140°, preferably 132° to 138°, more preferably 134° to 136°, and even more preferably about 135°. A nanophase separation structure is formed in the phase difference layer 20. As will be described in more detail later, cellulose resins have a relatively low glass transition temperature (Tg), while ester resins have a relatively high Tg. According to one embodiment of the present invention, the phase difference layer 20 having inverse dispersion characteristics (wavelength dependence of inverse dispersion where the phase difference value increases with the wavelength of the measured light) with Re(450) / Re(550) in the above range contains a cellulose resin with a relatively low Tg and an ester resin with a relatively high Tg. Therefore, the phase difference layer 20 can be given a balanced effect of reducing residual stress by the cellulose resin and reducing shrinkage by the ester resin. Since a nanophase separation structure is formed in such a phase difference layer 20, rapid shrinkage of the phase difference layer 20 can be suppressed in a high temperature and high humidity environment (for example, 110°C and 85%RH (relative humidity)), and crack formation in the phase difference layer 20 and / or peeling of the phase difference layer 20 from the polarizer 11 can be suppressed. This makes it possible to suppress the occurrence of appearance defects of the polarizing plate 100 with a phase difference layer in a high temperature and high humidity environment. Furthermore, when a nanophase separation structure is formed in the phase difference layer 20, the function as an inverse dispersion phase difference layer can be stably ensured.

[0011] In this specification, "nanophase separation structure" refers to a structure in which two components with different electron densities are phase-separated by domain sizes on the nano-order (typically at the level of several tens of nanometers). Cellulose resins and ester resins may have a sea-island structure or a co-continuous structure. Examples of means for confirming the nanophase separation structure include transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), and small-angle X-ray scattering (SAXS), with TEM observation of the cross-section of the phase difference layer 20 being preferred. TEM observation will be described in detail in the examples. When a nanophase separation structure is formed in the phase difference layer 20, two types of domains with different electron densities can be confirmed by TEM observation of the cross-section of the phase difference layer 20, and it can be confirmed that the size (maximum length) of all domains is less than 100 nm.

[0012] The in-plane birefringence Δn(550) of the phase difference layer 20 is, for example, 0.0020 or more, preferably 0.0030 or more, more preferably 0.0040 or more, and for example, 0.0070 or less, preferably 0.0060 or less, more preferably 0.0055 or less. The Nz coefficient of the phase difference layer 20 is, for example, 0.9 or more and 3 or less, preferably 1.0 or more and 1.5 or less.

[0013] In one embodiment, the content of the cellulose resin is typically more than 50% by mass, preferably 60% by mass or more, and more preferably 70% by mass or more, when the total amount of the cellulose resin and ester resin is taken as 100% by mass. As long as the content of the cellulose resin is above the lower limit, the cellulose resin and ester resin can stably form a nanophase separation structure. The upper limit of the content of the cellulose resin is typically 90% by mass or less.

[0014] In one embodiment, the phase difference layer 20 is a stretched film obtained by stretching a resin film containing a cellulose resin and an ester resin. As will be described in detail later, the stretched film (phase difference film) is typically prepared by uniaxially stretching a resin film containing a cellulose resin and an ester resin in a predetermined direction. As described above, a nanophase separation structure is formed in such a phase difference film. The phase difference film alone, and the polarizing plate with a phase difference layer (phase difference film) equipped with the phase difference film (phase difference layer), have excellent flexibility in the stretching direction and in directions perpendicular to the stretching direction. In particular, phase difference films having a nanophase separation structure exhibit significantly superior flexibility in the direction perpendicular to the stretching direction compared to phase difference films without a nanophase separation structure (e.g., stretched resin films, liquid crystal polymer films), and polarizing plates with a phase difference layer equipped with a phase difference film (phase difference layer) having a nanophase separation structure show a similar trend.

[0015] The number of MIT cycles for the phase difference film in the stretching direction is, for example, 800 or more, preferably 1000 or more, more preferably 1500 or more, and for example, 2500 or less. The number of MIT cycles can be measured in accordance with JIS P 8115 (the same applies hereinafter). The number of MIT cycles of the phase difference film in the direction perpendicular to the stretching direction is, for example, 400 or more, preferably 500 or more, more preferably 600 or more, even more preferably 1000 or more, and particularly preferably 1300 or more, and for example, 2000 or less. The number of MIT cycles of the polarizing plate 100 with a phase difference layer in the stretching direction is, for example, 300 or more, preferably 500 or more, more preferably 600 or more, and for example, 1000 or less. The number of MIT cycles of the polarizing plate 100 with a phase difference layer in a direction perpendicular to the stretching direction is, for example, 300 or more, preferably 400 or more, more preferably 450 or more, even more preferably 500 or more, and particularly preferably 550 or more, and for example, 900 or less.

[0016] In one embodiment, the phase difference layer 20 is attached to the polarizer plate 10 via an adhesive layer 30. In the illustrated example, the phase difference layer 20 is attached to the polarizer 11 via an adhesive layer 30. The adhesive layer 30 may be formed directly on the polarizer 11, or it may be formed on the protective layer if the polarizer plate 10 has a protective layer on the side of the polarizer 11 opposite to the viewing side. The adhesive layer 30 may be an adhesive layer or an adhesive layer. The adhesive layer 30 is preferably an adhesive layer. If the adhesive layer 30 is an adhesive layer, an example of an adhesive constituting the adhesive layer is a (meth)acrylic adhesive. "(Meth)acrylic" refers to acrylic and / or methacrylic adhesives. The thickness of the adhesive layer is, for example, 3.5 μm or more and 35 μm or less. When the adhesive layer 30 is an adhesive layer, examples of adhesives constituting the adhesive layer include thermosetting adhesives and ultraviolet curing adhesives, and more preferably (meth)acrylic ultraviolet curing adhesives. "(meth)acrylic" refers to acrylic and / or methacrylic. The thickness of the adhesive layer is, for example, 0.4 μm to 3.0 μm.

[0017] In one embodiment, the polarizing plate 100 with a phase difference layer further comprises an adhesive layer 40 provided on the side of the phase difference layer 20 opposite to the polarizer 11. This allows the polarizing plate 100 with a phase difference layer to be attached to an image display cell, which will be described later. Examples of adhesives that make up the adhesive layer 40 include (meth)acrylic adhesives. The thickness of the adhesive layer 40 is, for example, 3.5 μm or more and 35 μm or less. Furthermore, it is preferable that a release liner 50 is temporarily attached to the surface of the adhesive layer 40 until the polarizing plate 100 with a phase difference layer is put into use. By temporarily attaching the release liner, the adhesive layer is protected and roll formation becomes possible.

[0018] The polarizing plate with a phase difference layer may be in the form of a single sheet or a long sheet. In this specification, "long sheet" means an elongated shape in which the length is sufficiently long relative to the width, and for example, includes an elongated shape in which the length is 10 times or more, preferably 20 times or more, relative to the width. The long polarizing plate with a phase difference layer can be wound into a roll.

[0019] The following describes each component that makes up the polarizing plate 100 with a phase difference layer.

[0020] B. Polarizing plate B-1.Polarizer Any suitable polarizer can be used as the polarizer 11. For example, the resin film forming the polarizer may be a single layer resin film or a laminate of two or more layers.

[0021] Specific examples of polarizers composed of a single layer of resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films, which have been subjected to dyeing and stretching treatments with dichroic substances such as iodine or dichroic dyes, as well as polyene-based oriented films such as dehydrated PVA or dehydrochlorinated polyvinyl chloride. Preferably, polarizers obtained by dyeing a PVA film with iodine and uniaxially stretching are used because they have excellent optical properties.

[0022] The above-mentioned iodine dyeing is carried out, for example, by immersing the PVA film in an iodine aqueous solution. The stretching ratio for the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, or during the dyeing process. Alternatively, dyeing may be performed after stretching. If necessary, the PVA film may be subjected to swelling, crosslinking, washing, drying, etc. For example, immersing the PVA film in water and washing it before dyeing can not only wash away dirt and blocking agents from the surface of the PVA film, but also swell the PVA film to prevent uneven dyeing.

[0023] Specific examples of polarizers obtained using a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, and obtaining a laminate of the resin substrate and the PVA-based resin layer; or by stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In one embodiment of the present invention, preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may optionally include air stretching the laminate at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. In addition, in one embodiment of the present invention, the laminate is preferably subjected to a drying shrinkage treatment in which it shrinks by 2% or more in the width direction by heating while being transported in the longitudinal direction. Typically, the manufacturing method of this embodiment includes applying an air-assisted stretching treatment, a dyeing treatment, a water-based stretching treatment, and a drying shrinkage treatment to the laminate in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of PVA even when PVA is coated on a thermoplastic resin, making it possible to achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as a decrease in the orientation of PVA and dissolution when immersed in water in the subsequent dyeing and stretching processes, making it possible to achieve high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain halides. This makes it possible to improve the optical properties of polarizers obtained through processing steps that involve immersing the laminate in a liquid, such as dyeing and water-based stretching. Furthermore, by shrinking the laminate in the width direction through a drying shrinkage treatment, the optical properties can be improved.The resulting resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate / polarizer laminate, and any appropriate protective layer may be laminated onto the peeled surface according to the purpose. Details of such polarizer manufacturing methods are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0024] The thickness of the polarizer is, for example, 1 μm to 80 μm, preferably 1 μm to 15 μm, more preferably 1 μm to 12 μm, even more preferably 3 μm to 12 μm, and particularly preferably 3 μm to 8 μm. When the thickness of the polarizer is within this range, curling during heating can be well suppressed, and good durability of the appearance during heating can be obtained.

[0025] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, and more preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or higher, more preferably 99.0% or higher, and even more preferably 99.9% or higher.

[0026] B-2.Protective layer The polarizing plate 10 may further include a protective layer. The protective layer is provided on at least one surface of the polarizer. In the illustrated example, the polarizing plate 10 includes a protective layer 12 provided on the viewing side of the polarizer 11.

[0027] The protective layer is formed from any suitable film that can be used as a protective layer for the polarizer. Specific examples of materials that make up the main component of the film include cellulosic resins such as triacetylcellulose (TAC), and transparent resins such as polyester, polyvinyl alcohol, polycarbonate, polyamide, polyimide, polyethersulfone, polysulfone, polystyrene, polynorbornene, polyolefin, (meth)acrylic, and acetate. Thermosetting resins or UV-curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone 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.

[0028] If the polarizing plate 10 includes a protective layer located on the outermost surface of the image display device described later, the protective layer may be subjected to surface treatments such as hard coating, anti-reflective coating, anti-sticking coating, and anti-glare coating, as necessary.

[0029] The thickness of the protective layer is typically 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, and even more preferably 5 μm to 150 μm. If a surface treatment is applied, the thickness of the protective layer includes the thickness of the surface treatment layer.

[0030] C. Retardation layer The phase difference layer 20 typically exhibits refractive index characteristics such as nx > ny ≥ nz. "ny = nz" includes not only the case where ny and nz are completely identical, but also the case where ny and nz are substantially identical. A phase difference layer 20 with refractive index characteristics nx > ny = nz is sometimes referred to as a "positive A plate," etc. A phase difference layer 20 with refractive index characteristics nx > ny > nz is sometimes referred to as a "negative B plate," etc. The thickness of the phase difference layer 20 is, for example, 10 μm or more, preferably 20 μm or more, and for example, 80 μm or less, preferably 60 μm or less. The thickness of the phase difference layer 20 can be arbitrarily and appropriately adjusted according to the application of the polarizing plate with the phase difference layer, and is not limited to the above range. The thickness of the phase difference layer 20 may be, for example, 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. If the thickness of the phase difference layer is below the above upper limit, the flexibility of the polarizing plate with the phase difference layer can be further improved, and the number of MITs of the polarizing plate with the phase difference layer can be improved. In this case, the lower limit of the thickness of the phase difference layer is typically 5 μm or more.

[0031] As described above, the phase difference layer 20 contains a cellulose resin and an ester resin. The cellulose resin exhibits positive birefringence. The ester resin exhibits negative birefringence. Here, "exhibiting positive birefringence" means that when the polymer is oriented by stretching or the like, the refractive index in the direction perpendicular to the stretching direction becomes relatively smaller. In other words, it means that the refractive index in the stretching direction becomes larger. "Exhibiting negative birefringence" means that when the polymer is oriented by stretching or the like, the refractive index in the stretching direction becomes relatively smaller. In other words, it means that the refractive index in the direction perpendicular to the stretching direction becomes larger.

[0032] C-1. Cellulose resin Cellulose resins are typically polymers in which β-glucose units are polymerized in a linear manner, and have the constituent units shown in the following formula (1). [ka] (In formula (1), each of R1 to R3 represents a hydrogen atom or a substituent having 1 to 12 carbon atoms).

[0033] Examples of substituents having 1 to 12 carbon atoms represented by R1 to R3 in formula (1) above include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, decanyl, dodecanyl, isobutyl, and t-butyl groups; cycloalkyl groups such as cyclohexyl groups; aryl groups such as phenyl and naphthyl groups; aralkyl groups such as benzyl groups; acyl groups such as acetyl and propionyl groups; cyanoalkyl groups such as cyanoethyl groups; aminoalkyl groups such as aminoethyl groups; and hydroxyalkyl groups such as 2-hydroxyethyl and 3-hydroxypropyl groups. In equation (1) above, R1 to R3 may be the same or different from each other. Preferably, R1 to R3 in formula (1) above are a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, more preferably a hydrogen atom and an alkyl group having 1 to 4 carbon atoms, and even more preferably a hydrogen atom and an ethyl group.

[0034] The degree of substitution (hereinafter referred to as DS) of cellulose resins is typically between 1.5 and 2.95, preferably between 1.8 and 2.8. DS represents the percentage of hydroxyl groups substituted in the cellulose resin, with DS being 3 when 100% substitution occurs. DS can be calculated from the peak area of ​​gas chromatography, as described in the 17th edition of the Japanese Pharmacopoeia.

[0035] The number-average molecular weight (Mn) of cellulose resins, in terms of standard polystyrene equivalent, is, for example, 1 × 10⁻⁶. 3 The above 1 x 10 6 Preferably, 5 × 10 3 The above 2 x 10 5 The following applies: The manganese content (Mn) of the cellulose resin can be calculated from the elution curve measured by gel permeation chromatography (GPC). If the Mn content of the cellulose resin is within the above range, the mechanical properties and / or moldability of the phase difference layer can be improved.

[0036] The glass transition temperature (Tg) of cellulose-based resins is, for example, 140°C or lower, preferably 135°C or lower, and for example, 120°C or higher, preferably 125°C or higher. The glass transition temperature (Tg) of cellulose-based resins can be measured by a thermal analyzer such as a DSC (Differential Scanning Calorimetry).

[0037] Specific examples of cellulosic resins include alkylcellulose such as methylcellulose, ethylcellulose, and propylcellulose; hydroxyalkylcellulose such as hydroxyethylcellulose and hydroxypropylcellulose; aralkylcellulose such as benzylcellulose; cyanoalkylcellulose such as cyanoethylcellulose; carboxyalkylcellulose such as carboxymethylcellulose and carboxyethylcellulose; carboxyalkylalkylcellulose such as carboxymethylmethylcellulose and carboxymethylethylcellulose; and aminoalkylcellulose such as aminoethylcellulose. Cellulosic resins can be used alone or in combination. Among cellulosic resins, alkylcellulose is preferred, and ethylcellulose is more preferred.

[0038] C-2. Ester resins Ester resins typically have the constituent units shown in formula (2) and formula (3) below. [ka] (In formula (2), R4 represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms; R 5a R represents one selected from an alkyl group having 1 to 12 carbon atoms, a nitro group, a bromo group, an iodo group, a cyano group, a chloro group, a sulfonic acid group, a carboxylic acid group, a fluoro group, or a thiol group; R 5brepresents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms; R6 represents a species selected from a hydrogen atom, a nitro group, a bromo group, an iodo group, a cyano group, a chloro group, a sulfonic acid group, a carboxylic acid group, a fluoro group, a phenyl group, a thiol group, an amide group, an amino group, a hydroxy group, an alkoxy group having 1 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms.) [Chemical formula] (In formula (3), R7 represents a 5-membered heterocyclic residue or a 6-membered heterocyclic residue containing at least one nitrogen atom or oxygen atom as a hetero atom (the 5-membered heterocyclic residue and the 6-membered heterocyclic residue may form a condensed ring structure with other cyclic structures).)

[0039] The structural unit shown in the above formula (2) is a cinnamic acid ester residue unit. Examples of the alkyl group having 1 to 12 carbon atoms represented by R4 in the above formula (2) include a methyl group, an ethyl group, an isopropyl group, an n-propyl group, an n-butyl group, an s-butyl group, a t-butyl group, an isobutyl group, and an ethylhexyl group. Among R4 in the above formula (2), preferably, an alkyl group having 1 to 4 carbon atoms is included, and more preferably, an ethyl group and an isobutyl group are included.) Among R 5a in the above formula (2), preferably, an alkyl group having 1 to 12 carbon atoms and a cyano group are included, more preferably, an alkyl group having 1 to 4 carbon atoms and a cyano group are included, and still more preferably, a cyano group is included.) Among R 5b in the above formula (2), preferably, a hydrogen atom and an alkyl group having 1 to 4 carbon atoms are included.) R6 in the above formula (2) may be bonded to the benzene ring only once or may be bonded to the benzene ring two or more times. Among R6 in the above formula (2), preferably, a carboxylic acid group and a hydroxy group are included.)

[0040] Specific examples of the constituent units (cinnamic acid ester residue units) shown in formula (2) above include α-cyano-4-hydroxycinnamate methyl residue unit, α-cyano-2-hydroxycinnamate ethyl residue unit, α-cyano-3-hydroxycinnamate ethyl residue unit, α-cyano-4-hydroxycinnamate ethyl residue unit, α-cyano-4-hydroxycinnamate n-propyl residue unit, α-cyano-4-hydroxycinnamate isopropyl residue unit, α-cyano-4-hydroxycinnamate n-butyl residue unit, and α-cyano-4-hydroxy α-cyano-hydroxycinnamic acid ester residue units such as isobutyl xycinnamate residue units, α-cyano-4-hydroxycinnamate s-butyl residue units, α-cyano-2,4-dihydroxycinnamate methyl residue units; α-cyano-carboxycinnamic acid ester residue units such as α-cyano-4-carboxycinnamate methyl residue units, α-cyano-4-carboxycinnamate ethyl residue units, α-cyano-2,3-dicarboxycinnamate methyl residue units, α-cyano-2,3-dicarboxycinnamate ethyl residue units; α -Cyano-2-carboxy-3-hydroxycinnamate methyl residue unit, α-cyano-2-carboxy-3-hydroxycinnamate ethyl residue unit, and other α-cyano-2-carboxy-3-hydroxycinnamate ethyl residue unit; 3-alkyl-3-(hydroxyphenyl)-propa-2-enoate methyl residue unit, 3-ethyl-3-(hydroxyphenyl)-propa-2-enoate ethyl residue unit, and other 3-methyl-3-(carboxyphenyl) )-propa-2-enoic acid methyl residue unit, 3-ethyl-3-(carboxyphenyl)-propa-2-enoic acid ethyl residue unit, and other 3-alkyl-3-(carboxyphenyl)-propa-2-enoic acid ester residue units; 2-cyano-3-methyl-3-(hydroxyphenyl)-propa-2-enoic acid methyl residue unit, 2-cyano-3-ethyl-3-(hydroxyphenyl)-propa-2-enoic acid ethyl residue unit, and other 2-cyano-3-alkyl-3-(hydroxyphenyl)-propa-2-enoic acid ester residue units;Examples include 2-cyano-3-alkyl-3-(carboxyphenyl)-propa-2-enoic acid ester residue units such as 2-cyano-3-methyl-3-(carboxyphenyl)-propa-2-enoic acid methyl residue units and 2-cyano-3-ethyl-3-(carboxyphenyl)-propa-2-enoic acid ethyl residue units.

[0041] The ester resin may contain only one of the constituent units shown in formula (2) above, or it may contain two or more. Among the constituent units shown in formula (2) above, preferred examples include α-cyano-hydroxycinnamic acid ester residue units, α-cyano-carboxycinnamic acid ester residue units, 3-alkyl-3-(hydroxyphenyl)-propa-2-enoic acid ester residue units, and 3-alkyl-3-(carboxyphenyl)-propa-2-enoic acid ester residue units.

[0042] The content of the constituent units of formula (2) in the ester resin is, for example, 21 mol% or more, for example, 70 mol% or less, preferably 60 mol% or less, and more preferably 49 mol% or less. The content of each constituent unit in the ester resin is, for example, 1 It can be measured by 1H-NMR.

[0043] Specific examples of the ring structure represented by R7 in formula (3) above include 1-vinylpyrrole residue units, 2-vinylpyrrole residue units, 1-vinylindole residue units, 9-vinylcarbazole residue units, 2-vinylquinoline residue units, 4-vinylquinoline residue units, N-vinylphthalimide residue units, N-vinylsuccinimide residue units, 2-vinylfuran residue units, and 2-vinylbenzofuran residue units, with 9-vinylcarbazole residue units and N-vinylphthalimide residue units being preferred.

[0044] The ester resin may contain only one of the constituent units shown in formula (3) above, or it may contain two or more. The content of the constituent unit of formula (3) in the ester resin is, for example, 21 mol% or more, preferably 35 mol% or more, and for example, 70 mol% or less, preferably 60 mol% or less.

[0045] The ester resin preferably has, in addition to the constituent units shown in (2) and (3) above, the constituent unit shown in the following formula (4). [ka] (In formula (4), R8 and R9 each represent one selected from a hydrogen atom, a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 3 to 12 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms.) In formula (4) above, examples of linear alkyl groups having 1 to 12 carbon atoms represented by R8 and R9 include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, and n-hexyl group. In formula (4) above, the branched alkyl groups having 3 to 12 carbon atoms represented by R8 and R9 include, for example, isopropyl group, isobutyl group, sec-butyl group, and tert-butyl group. In formula (4) above, examples of cyclic alkyl groups having 3 to 6 carbon atoms represented by R8 and R9 include cyclopropyl group, cyclobutyl group, and cyclohexyl group. In equation (4) above, R8 and R9 may be the same or different from each other. In formula (4) above, R8 is preferably a hydrogen atom and a linear alkyl group having 1 to 12 carbon atoms, and more preferably a hydrogen atom and a methyl group. In formula (4) above, R9 is preferably a branched alkyl group having 3 to 12 carbon atoms, and more preferably a branched alkyl group having 3 to 8 carbon atoms.

[0046] The constituent units shown in formula (4) above are typically acrylic resin residue units. Specific examples of the constituent units shown in formula (4) above include acrylic acid residue units, methacrylic acid residue units, 2-ethyl acrylic acid residue units, 2-propyl acrylic acid residue units, 2-isopropyl acrylic acid residue units, 2-pentyl acrylic acid residue units, 2-hexyl acrylic acid residue units, methyl acrylate residue units, ethyl acrylate residue units, n-propyl acrylate residue units, isopropyl acrylate residue units, n-butyl acrylate residue units, isobutyl acrylate residue units, sec-butyl acrylate residue units, n-pentyl acrylate residue units, isopentyl acrylate residue units, sec-pentyl acrylate residue units, 3-pentyl acrylate residue units, neopentyl acrylate residue units, n-hexyl acrylate residue units, isohexyl acrylate residue units, neohexyl acrylate residue units, methyl methacrylate residue units, ethyl methacrylate residue units, and methacrylate residue units. Examples include n-propyl methacrylate residue units, isopropyl methacrylate residue units, n-butyl methacrylate residue units, isobutyl methacrylate residue units, sec-butyl methacrylate residue units, n-pentyl methacrylate residue units, isopentyl methacrylate residue units, sec-pentyl methacrylate residue units, 3-pentyl methacrylate residue units, neopentyl methacrylate residue units, n-hexyl methacrylate residue units, isohexyl methacrylate residue units, neohexyl methacrylate residue units, methyl 2-ethylacrylate residue units, ethyl 2-ethylacrylate residue units, n-propyl 2-ethylacrylate residue units, isopropyl 2-ethylacrylate residue units, n-butyl 2-ethylacrylate residue units, isobutyl 2-ethylacrylate residue units, and sec-butyl 2-ethylacrylate residue units, with isobutyl acrylate residue units being preferred.

[0047] The ester resin may contain only one of the constituent units shown in formula (4) above, or it may contain two or more. The content of the constituent unit of formula (4) in the ester resin is, for example, 0 mol% or more, preferably 1 mol% or more, and for example, 30 mol% or less.

[0048] Ester resins may contain monomer residue units other than those in formulas (2) to (4) above. Examples of such monomer residue units include styrene residues such as styrene residues and α-methylstyrene residues; vinylnaphthalene residues; vinyl ester residues such as vinyl acetate residues and vinyl propionate residues; vinyl ether residues such as methyl vinyl ether residues, ethyl vinyl ether residues and butyl vinyl ether residues; N-substituted maleimide residues such as N-methylmaleimide residues, N-cyclohexylmaleimide residues and N-phenylmaleimide residues; acrylonitrile residues; methacrylonitrile residues; fumarate ester residues; fumarate residues; and olefin residues such as ethylene residues and propylene residues.

[0049] The number-average molecular weight (Mn) of ester resins on a standard polystyrene basis is, for example, 1 × 10⁻⁶. 3 The above 5 x 10 6 The following is preferable: 5 × 10 3 The above 3 x 10 5 The following applies: The manganese (Mn) content of the ester resin can be calculated from the elution curve measured by gel permeation chromatography (GPC). If the manganese content of the ester resin is within the above range, the mechanical properties and / or moldability of the phase difference layer can be improved.

[0050] The glass transition temperature (Tg) of ester resins is, for example, 220°C or lower, preferably 210°C or lower, and for example, 180°C or higher, preferably 190°C or higher. The glass transition temperature (Tg) of ester resins can be measured by a thermal analyzer such as a DSC (Differential Scanning Calorimetry).

[0051] Specific examples of such ester resins include α-cyano-2-hydroxycinnamic acid ester-styrene-acrylic acid ester copolymer, α-cyano-2-hydroxycinnamic acid ester-2-vinylnaphthalene-acrylic acid ester copolymer, α-cyano-2-hydroxycinnamic acid ester-1-vinylindole-acrylic acid ester copolymer, α-cyano-2-hydroxycinnamic acid ester-9-vinylcarbazole-acrylic acid ester copolymer, α-cyano-3-hydroxycinnamic acid ester-styrene-acrylic acid ester copolymer, α -Cyano-3-hydroxycinnamic acid ester-2-vinylnaphthalene-acrylic acid ester copolymer, α-cyano-3-hydroxycinnamic acid ester-1-vinylindole-acrylic acid ester copolymer, α-cyano-3-hydroxycinnamic acid ester-9-vinylcarbazole-acrylic acid ester copolymer, α-cyano-4-hydroxycinnamic acid ester-styrene-acrylic acid ester copolymer, α-cyano-4-hydroxycinnamic acid ester-2-vinylnaphthalene-acrylic acid ester copolymer, α-cyano-4-hydroxycinnamic acid ester Stel-1-vinylindole-acrylic acid copolymer, α-cyano-4-hydroxycinnamic acid ester-9-vinylcarbazole-acrylic acid copolymer, α-cyano-2-hydroxycinnamic acid ester-styrene-methacrylic acid copolymer, α-cyano-2-hydroxycinnamic acid ester-2-vinylnaphthalene-methacrylic acid copolymer, α-cyano-2-hydroxycinnamic acid ester-1-vinylindole-methacrylic acid copolymer, α-cyano-2-hydroxycinnamic acid ester-9-vinylcarbazole α-Cyano-3-hydroxycinnamic acid-styrene-methacrylic acid copolymer, α-Cyano-3-hydroxycinnamic acid-2-vinylnaphthalene-methacrylic acid copolymer, α-Cyano-3-hydroxycinnamic acid-1-vinylindole-methacrylic acid copolymer, α-Cyano-3-hydroxycinnamic acid-9-vinylcarbazole-methacrylic acid copolymer, α-Cyano-4-hydroxycinnamic acid-styrene-methacrylic acid copolymer,Examples include α-cyano-4-hydroxycinnamic acid ester-2-vinylnaphthalene-methacrylate copolymer, α-cyano-4-hydroxycinnamic acid ester-1-vinylindole-methacrylate copolymer, and α-cyano-4-hydroxycinnamic acid ester-9-vinylcarbazole-methacrylate copolymer.

[0052] C-3. Other Additives The phase difference layer 20 may contain additives in any appropriate proportion in addition to the resin components described above. Examples of additives include antioxidants such as hindered phenol antioxidants, phosphorus antioxidants, sulfur antioxidants, lactone antioxidants, amine antioxidants, hydroxylamine antioxidants, vitamin E antioxidants, and other antioxidants; hindered amine light stabilizers; UV absorbers such as benzotriazole, benzophenone, triazine, and benzoate; surfactants; polymer electrolytes; conductive complexes; pigments; dyes; antistatic agents; antiblocking agents; and lubricants.

[0053] C-4. Method for manufacturing a phase difference layer Next, one embodiment of the method for manufacturing a phase difference layer will be described. In one embodiment, the method for manufacturing a phase difference layer includes the steps of: dissolving the cellulose resin and the ester resin in a solvent to prepare a resin solution; coating the resin solution onto a substrate; heating the coating on the substrate to prepare a resin film; stretching the resin film; and thermally shrinking the resin film in the stretching direction.

[0054] First, the cellulose resin and the ester resin are dissolved in a solvent in the proportion of the cellulose resin described in Section A. Examples of solvents include halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, and dichlorobenzene; phenols such as phenol and chlorophenol; aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene, mesitylene, and dimethoxybenzene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), cyclohexanone, cyclopentanone (CPN), 2-pyrrolidone, and N-methyl-2-pyrrolidone; ester solvents such as ethyl acetate and butyl acetate; butanol, t-butyl alcohol, glycerin, and ethyl acetate. Examples of solvents include alcohol-based solvents such as ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol, and 2-methyl-2,4-pentanediol; amide-based solvents such as dimethylformamide and dimethylacetamide; nitrile-based solvents such as acetonitrile and butyronitrile; ether-based solvents such as 1,3-dioxolane, cyclopentyl methyl ether (CPME), propylene glycol methyl ether acetate (PGMEA), diethyl ether, dibutyl ether, and tetrahydrofuran; carbon disulfide, ethyl cellosolve, butyl cellosolve, and mixtures thereof.

[0055] Among the solvents, mixed solvents are preferred. Examples of mixed solvent combinations include ester solvent / aromatic hydrocarbons, ether solvent / aromatic hydrocarbons, ester solvent / ether solvent, ester solvent / alcohol solvent, ester solvent / ketone solvent, two types of ether solvents, and two types of ester solvents.

[0056] Hansen solubility parameter distance (hereinafter referred to as HSP distance) between cellulose resins and solvents. *セルロース系 It may be referred to as the HSP distance.) is, for example, 12.00 or less, preferably 11.30 or less, and more preferably 11.20 or less. *セルロース系If the above upper limit is below, the stretching orientation in the phase difference layer can be improved. HSP distance *セルロース系 This can be calculated, for example, by the following formula (I). Note that HSP distance *セルロース系 The lower limit is typically 6.0 or higher. Equation (I): HSP distance *セルロース系 =[4(δ d2 -δ d1 ) 2 +( δ p2 -δ p1 ) 2 +( δ h2 -δ h1 ) 2 ] 0.5 (In formula (I), δ d1 This represents the intermolecular dispersion force energy of the solvent; δ d2 This represents the intermolecular dispersion force energy of cellulose resins; δ p1 This represents the dipole interaction energy between molecules in the solvent; δ p2 This represents the intermolecular dipole interaction energy of cellulose-based resins; δ h1 δ represents the hydrogen bond energy between molecules in the solvent; h2 This indicates the hydrogen bond energy between molecules in cellulose-based resins.

[0057] The HSP distance between the ester resin and the solvent (hereinafter referred to as HSP distance) *エステル系 It may be referred to as ) is, for example, 6.5 or less, preferably 6.0 or less, and for example, 2.0 or more. HSP distance *エステル系 This can be calculated, for example, by the following formula (II). Formula (II): HSP distance *エステル系 =[4(δ d3 -δ d1 ) 2 +( δ p3 -δ p1 ) 2 +( δ h3 -δ h1 ) 2 ] 0.5 (In formula (II), δ d3 This represents the intermolecular dispersion force energy of ester resins; δp3 This indicates the intermolecular dipole interaction energy of ester resins; δ h3 This indicates the intermolecular hydrogen bond energy of ester resins; δ d1 , δ p1 and δ h1 Each of these represents the intermolecular energy of the solvent, similar to that in equation (I) above.

[0058] (HSP distance *セルロース系 -HSP distance *エステル系 ) 2 For example, it is 60 or less, preferably 55 or less, more preferably 50 or less, even more preferably 45 or less, and especially preferably 30 or less. (HSP distance) *セルロース系 -HSP distance *エステル系 ) 2 If it is below the above upper limit, the inverse dispersion of the phase difference layer can be stably ensured. (HSP distance) *セルロース系 -HSP distance *エステル系 ) 2 The lower limit is, for example, 10 or more.

[0059] More preferably, the mixed solvent is an ester solvent / aromatic hydrocarbon, even more preferably ethyl acetate / toluene, and particularly preferably 60% by mass of ethyl acetate / 40% by mass of toluene. When the solvent is such a mixed solvent, the cellulose resin and the ester resin can form a nanophase separation structure more stably in the phase difference layer.

[0060] The solid content concentration in the resin solution is, for example, 1% by mass or more, preferably 5% by mass or more, and for example, 30% by mass or less, preferably 20% by mass or less.

[0061] Preferably, the resin solution is stirred for a predetermined time, then allowed to stand to remove bubbles. The stirring time is, for example, 5 minutes or more, preferably 10 minutes or more, and for example, 3 hours or less, preferably 1 hour or less. The defoaming time (standing time) is, for example, 30 minutes or more, preferably 1 hour or more, and for example, 5 hours or less, preferably 3 hours or less.

[0062] Next, the resin solution is applied to the substrate (typically a resin film). Any suitable method can be used for the application. An applicator can be used as an application method. This forms a coating film of the resin solution on the substrate.

[0063] Next, the coating on the substrate is heated to prepare a resin film. The heating temperature is, for example, 35°C to 165°C, and the heating time is 1 minute to 30 minutes. More specifically, such a heating process includes a primary heating process (drying process) heated at 165°C or lower, and a secondary heating process (annealing process) heated at 110°C or higher.

[0064] The drying process may be carried out in one stage or in multiple stages. Preferably, the drying process is carried out in multiple stages. When the drying process is carried out in multiple stages, the heating temperature for the first drying stage is set to, for example, 35°C to 65°C, preferably 45°C to 65°C, and the heating time for the first drying stage is set to, for example, 1 minute to 30 minutes, preferably 1 minute to 8 minutes. Thereafter, for each additional drying stage, the heating temperature is increased by, for example, 10°C to 130°C, preferably 10°C to 40°C. The heating time for each stage from the second stage onward is typically shorter than the heating time for the first drying stage, preferably 20 seconds to 20 minutes, more preferably 30 seconds to 5 minutes. The number of drying stages is preferably 2 to 4, more preferably 3 or fewer. The maximum temperature in the drying process is, for example, 165°C or less, preferably less than 130°C, more preferably less than 120°C, and even more preferably 115°C or less.

[0065] Subsequently, if necessary, the coating film heated in the drying step is cooled to, for example, 30°C or lower, preferably room temperature (23°C). Cooling the coating film after drying allows the nanophase separation structure formed in the drying step to be fixed, and the nanophase separation structure can be maintained without changing it in the subsequent annealing step. Next, the coating film is heated in the annealing step. The heating temperature in the annealing step is typically higher than the maximum temperature in the drying step. The heating temperature in the annealing step is, for example, 110°C or higher, preferably 120°C or higher, more preferably 130°C or higher, and for example, 180°C or lower, preferably 165°C or lower, more preferably 150°C or lower, and even more preferably 140°C or lower. The heating time in the annealing step is, for example, 1 minute or more, preferably 5 minutes or more, even more preferably 15 minutes or more, and for example, 60 minutes or less, preferably 45 minutes or less.

[0066] This forms a resin film on the substrate. The thickness of the resin film is, for example, between 70 μm and 200 μm. Next, the resin film is peeled off from the substrate.

[0067] Next, the resin film is stretched. In one embodiment, the resin film is stretched in the width direction perpendicular to the transport direction while being transported in the longitudinal direction (lateral stretching at the fixed end). The resin film may be stretched in one or more stages, and it is particularly preferable to stretch it in two stages. A method for manufacturing a phase difference layer by two-stage stretching includes: a first stretching step of stretching the resin film in the width direction; and a second stretching step of stretching the resin film after the first stretching step in the same direction as the first stretching step. The resin film is preferably preheated before stretching. The preheating temperature varies in relation to the Tg of the materials contained in the resin film and is set with respect to the Tg (Tg1) of the material with the lowest Tg. (Tg1) is, for example, the Tg of a cellulose resin. The preheating temperature is, for example, (Tg1)-20°C or higher, preferably (Tg1)-10°C or higher, and for example, (Tg1)+50°C or lower, preferably (Tg1)+40°C or lower. The stretching temperature is the same as the preheating temperature, for example, (Tg1)-20°C or higher, preferably (Tg1)-10°C or higher, and for example, (Tg1)+50°C or lower, preferably (Tg1)+40°C or lower. The stretching speed is, for example, 1 mm / second or more, preferably 2 mm / second or more, and for example, 200 mm / second or less, preferably 100 mm / second or less. The stretching ratio (when the resin film is stretched in two stages, the product of the stretching ratio of the first stretching step and the stretching ratio of the second stretching step) is, for example, 2.0 times or more, preferably 2.5 times or more, and for example, 8.0 times or less, preferably 7.5 times or less.

[0068] Next, the stretched resin film is heat-shrinked in the stretching direction. The heat shrinkage temperature is set with respect to (Tg1) in the same way as the preheating and stretching temperatures, for example, (Tg1)-20°C or higher, preferably (Tg1)-15°C or higher, and for example, (Tg1)+45°C or lower, preferably (Tg1)+35°C or lower. The heat shrinkage temperature is more preferably below the stretching temperature. The shrinkage rate is typically 1% to 5%. The phase difference layer 20 is manufactured as described above.

[0069] D. Image display device The polarizing plates with phase difference layers described in sections A to C above can be applied to image display devices. Therefore, one embodiment of the present invention also includes an image display device using such a polarizing plate with a phase difference layer. Typical examples of image display devices include liquid crystal display devices and organic EL display devices. An image display device according to an embodiment of the present invention comprises an image display cell and a polarizing plate with a phase difference layer described in sections A to C above. Typically, an image display device comprises an image display panel including an image display cell and the polarizing plate with a phase difference layer arranged on the viewing side thereof. Note that an image display device may be referred to as an optical display device, an image display panel may be referred to as an optical display panel, and an image display cell may be referred to as an optical display cell. [Examples]

[0070] 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.

[0071] (1) Measurement of phase difference The phase difference values ​​of the phase difference layers used in the examples and comparative examples were automatically measured using Axoscan (manufactured by Axometrics). The measurement wavelength was 450 nm or 550 nm, and the measurement temperature was 23°C.

[0072] (2) Observation of nanophase separation structure Samples were taken from the vicinity of the center in the thickness direction of the phase difference films used in the examples and comparative examples (specifically, the area within ±20% of the center in the thickness direction of the phase difference film when the thickness of the phase difference film is set to 100%), and the cross-section of the phase difference film was observed using TEM (HT7820, Hitachi, Ltd.) by an ultrathin sectioning method including heavy metal staining (cross-sectional TEM observation). The analyzed photographs were visually evaluated according to the following criteria. ○: The size (maximum length) of all domains is less than 100 nm. △: Contains a mixture of domains smaller than 100nm and domains larger than 100nm. ×: All domains are larger than 100nm in size (maximum length).

[0073] (3) HAST (High Accelerated Stress Test) test The polarizing plates with phase difference layers obtained in the examples and comparative examples were attached to glass plates using an adhesive layer to prepare the samples. Next, the samples were placed in a pressurized humidified oven and held at 110°C / 85%RH for 36 hours, after which their appearance was visually evaluated according to the following criteria. ○: No cracks and / or peeling. ×: Cracks and / or peeling present.

[0074] (4) MIT exam MIT tests were performed on the phase difference films used in the examples and comparative examples, and on the polarizing plates with phase difference layers obtained in the examples and comparative examples. The MIT tests were conducted in accordance with JIS P 8115. Specifically, each of the phase difference film and the polarizing plate with a phase difference layer was cut to a length of 15 cm and a width of 1.5 cm, with the stretching direction being the width direction (TD direction) and the direction perpendicular to the stretching direction being the longitudinal direction (MD direction), to be used as measurement samples. The measurement samples were mounted on an MIT folding fatigue tester BE-202 (manufactured by Tester Sangyo Co., Ltd.) (load 1.0 kgf, clamp R: 0.38 mm), and repeated bending was performed in the width direction (TD direction) and longitudinal direction (MD direction) at a test speed of 90 cpm and a bending angle of 90°. The number of bending cycles at which the measurement sample broke was taken as the test value. The test values ​​were evaluated according to the following criteria. ○: For polarizing plates with a phase difference layer, the test value in the TD direction is 500 times or more, and the test value in the MD direction is 300 times or more. ×: In a polarizing plate with a phase difference layer, the test value in the TD direction is less than 500 cycles, and / or the test value in the MD direction is less than 300 cycles.

[0075] <<Production Example 1: Synthesis of Negative Birefringence Ester Resin A (9-Vinylcarbazole / α-Cyano-4-Hydroxycinnamate Isobutyl / Acrylate Isobutyl)>> 12.20 g of 9-vinylcarbazole, 7.74 g of isobutyl α-cyano-4-hydroxycinnamate, 4.05 g of isobutyl acrylate, and 0.453 g of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane and 36.00 g of methyl ethyl ketone, which are polymerization initiators, were placed in a 50 mL glass ampoule. After repeated nitrogen purging and pressure release, the ampoule was sealed under reduced pressure. Radical polymerization was carried out by placing this ampoule in a 54°C constant temperature bath and maintaining it for 24 hours. After the polymerization reaction was complete, the polymer was removed from the ampoule, 100 g of tetrahydrofuran was added, and this polymer solution was added dropwise to 800 g of methanol / water mixed solvent (mass ratio 80 / 20) to precipitate. After filtration, the filtrate was washed five times with 110 g of methanol / water mixed solvent (mass ratio 90 / 10) and filtered again. The obtained resin was vacuum-dried at 80°C for 10 hours to yield 22.3 g of a cinnamic acid ester copolymer exhibiting negative birefringence. The number-average molecular weight of the obtained polymer was 50,000, and the ratio of residue units was 50 mol% 9-vinylcarbazole residue units, 25 mol% α-cyano-4-hydroxycinnamate isobutyl residue units, and 25 mol% isobutyl acrylate residue units.

[0076] <<Production Example 2: Synthesis of Ester Resin B (α-Cyano-4-Hydroxycinnamate Ethyl / 9-Vinylcarbazole Copolymer)>> In a 50 mL glass ampoule, 5.0 g of ethyl α-cyano-4-hydroxycinnamate, 4.4 g of 9-vinylcarbazole, 0.17 g of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane (a polymerization initiator), and 8.5 g of tetrahydrofuran were placed. After repeated nitrogen purging and pressure reduction, the ampoule was sealed under reduced pressure. Radical polymerization was carried out by placing this ampoule in a 62°C constant temperature bath and maintaining it for 48 hours. After the polymerization reaction was complete, the polymer was removed from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum-dried at 60°C for 10 hours to obtain 7.7 g of a cinnamic acid ester copolymer (ester resin B) exhibiting negative birefringence (yield: 82%). The obtained cinnamic acid ester copolymer had a number-average molecular weight of 22,000, and the ratio of constituent units was 58 mol% for 9-vinylcarbazole residues and 42 mol% for α-cyano-4-hydroxycinnamate ethyl residues.

[0077] <<Manufacturing Example 3: Fabrication of Polarizing Plates>> As a thermoplastic resin substrate, an amorphous isophthalic copolymer polyethylene terephthalate film (thickness: 100 μm) in a long length with a Tg of approximately 75°C was used, and one side of the resin substrate was subjected to corona treatment. A PVA aqueous solution (coating solution) was prepared by dissolving 100 parts by mass of a PVA-based resin, which was 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, with 13 parts by mass of potassium iodide. A PVA aqueous solution was applied to the corona-treated surface of a resin substrate and dried at 60°C to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate. The resulting laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130°C (air-assisted stretching). Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 4 parts by mass of boric acid with 100 parts by mass of water) (insolubilization treatment). Next, the polarizers were immersed for 60 seconds in a staining bath at a liquid temperature of 30°C (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by mass of water) while adjusting the concentration so that the final transmittance (Ts) of the polarizers obtained would be the desired value (staining treatment). Next, the material was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 3 parts by mass of potassium iodide and 5 parts by mass of boric acid with 100 parts by mass of water) (crosslinking treatment). Subsequently, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4% by weight, potassium iodide concentration 5% by weight) at a liquid temperature of 70°C, and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to achieve a total stretch ratio of 5.5 times (underwater stretching treatment). Subsequently, the laminate was immersed in a washing bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by mass of potassium iodide with 100 parts by mass of water) (washing treatment). Subsequently, the material was dried in an oven maintained at approximately 90°C while being brought into contact with a SUS (stainless steel) heated roll whose surface temperature was maintained at approximately 75°C (drying shrinkage treatment). In this way, a polarizer with a thickness of approximately 5 μm was formed on the resin substrate, and a laminate having a resin substrate / polarizer configuration was obtained. A protective layer of HC-TAC film (20 μm thick) was bonded to the polarizer surface (the side opposite to the resin substrate) of the resulting laminate. Next, the resin substrate was peeled off to obtain a polarizing plate having a protective layer / polarizer configuration.

[0078] [Examples 1 and 2] <<Preparation of Phase Contrast Film>> Ethyl cellulose (manufactured by Dow Chemical, Ethocel Standard 100, number average molecular weight Mn=58,000, weight average molecular weight Mw=180,000, Mw / Mn=3.2, degree of total substitution DS=2.51) and ester resin A obtained in Production Example 1 were dissolved in a mixed solvent of ethyl acetate / toluene = 60 / 40 (mass ratio) in the mass ratios shown in Table 1 to obtain a resin solution with a solid content concentration of 16% by mass. Next, the resin solution was stirred in a disper mixer for 30 minutes, and then allowed to stand for 2 hours to remove air bubbles. The degassed resin solution was then applied using an applicator onto a polyethylene terephthalate (PET) film (Toyobo Co., Ltd., Cosmoshine A4610) to a wet thickness of approximately 810 μm. Next, the coating was dried in an oven at 65°C for 6 minutes, 85°C for 1 minute, and 110°C for 2 minutes in three stages, and then left to stand at room temperature (23°C) for 60 minutes. After that, the dried coating was annealed again in an oven at 130°C for 60 minutes. As a result, a resin film was formed on the PET film. Next, the resin film was peeled from the PET film. The peeled resin film was preheated at 165°C for 1 minute, and then stretched 2.4 times at a fixed end transversely at a stretching temperature of 155°C and a stretching speed of 2 mm / second. Subsequently, the stretched resin film was shrunk by 2% in the width direction at a shrinking temperature of 155°C to obtain a phase difference film with a thickness of 46 μm. The refractive index characteristics of the phase difference film showed nx>ny>nz. The phase difference film was subjected to the measurement of the phase difference values ​​and observation of the nanophase separation structure described above. The results are shown in Table 1. <<Fabrication of polarizing plates with phase difference layer>> Next, a phase difference film was attached to the polarizer of the polarizer plate obtained in Manufacturing Example 3 using a (meth)acrylic adhesive. The thickness of the adhesive layer was 5 μm. The bonding was performed so that the angle between the absorption axis direction of the polarizer and the slow phase axis direction of the phase difference film was as shown in Table 1. Subsequently, a (meth)acrylic adhesive was applied to the phase difference film to form an adhesive layer. The thickness of the adhesive layer was 15 μm. A polarizing plate with a phase difference layer was obtained. The polarizing plate with a phase difference layer was subjected to the HAST test described above. The results are shown in Table 1.

[0079] [Example 3] A polarizing plate with a phase difference layer was obtained in the same manner as in Example 1, except that the ester resin A in Production Example 1 was replaced with ester resin B in Production Example 2. The phase difference film was subjected to the above-mentioned measurement of phase difference values ​​and observation of nanophase separation structure, and the polarizing plate with a phase difference layer was subjected to the above-mentioned HAST test. The results are shown in Table 1.

[0080] [Example 4] A polarizing plate with a phase difference layer was obtained in the same manner as in Example 1, except that the preheating temperature was changed to 162°C, the stretching temperature was changed to 162°C, and the stretching ratio was changed to 3.0 times. The thickness of the phase difference film was 36 μm. The phase difference film was subjected to the above-mentioned phase difference value measurement, observation of the nanophase separation structure, and MIT test, and the polarizing plate with a phase difference layer was subjected to the above-mentioned HAST test and MIT test. The results are shown in Table 2.

[0081] [Example 5] A resin film (before stretching) was prepared in the same manner as in Example 3, except that the wet film thickness of the resin solution was changed to 1050 μm. Next, the resin film was preheated at 162°C for 1 minute, then stretched 3.4 times at a fixed end at a stretching temperature of 162°C and a stretching speed of 2 mm / second. After that, it was preheated at 167°C for 1 minute, and then stretched 2.1 times at a fixed end at a stretching temperature of 167°C and a stretching speed of 2 mm / second. Subsequently, the stretched resin film was shrunk by 2% in the width direction at a shrinkage temperature of 155°C to obtain a phase difference film with a thickness of 20 μm. The obtained phase difference film was subjected to the above-mentioned phase difference value measurement, observation of the nanophase separation structure, and MIT testing. Subsequently, polarizing plates with a phase difference layer were prepared in the same manner as in Example 3. The obtained polarizing plates with a phase difference layer were subjected to the HAST test and MIT test described above. The results are shown in Table 2.

[0082] [Comparative Example 1] A polarizing plate with a phase difference layer was obtained in the same manner as in Example 1, except that the phase difference film was changed to a phase difference film prepared as described below. The phase difference film was subjected to the above-mentioned phase difference value measurement, observation of the nanophase separation structure, and MIT test, and the polarizing plate with a phase difference layer was subjected to the above-mentioned HAST test and MIT test. The results are shown in Tables 1 and 2. <<Preparation of Phase Contrast Film>> A batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and reflux condensers controlled to 100°C was used to prepare the reactor. The mixture consisted of 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 Part of mass (6.78×10 -5 A mixture of mol) and was charged. 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 mixture 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. Once the predetermined power level 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. Then, a long resin film with a thickness of 130 μm was 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 1.4 times at the free end longitudinally at 140°C to obtain a phase difference film with a thickness of 110 μm.

[0083] [Comparative Example 2] A polarizing plate with a phase difference layer was obtained in the same manner as in Example 1, except that the phase difference film was prepared using only ethyl cellulose instead of the ester resin A used in Production Example 1 as the resin material. The phase difference film was subjected to the above-mentioned measurement of phase difference values ​​and observation of the nanophase separation structure, and the polarizing plate with a phase difference layer was subjected to the above-mentioned HAST test. The results are shown in Table 1.

[0084] [Comparative Example 3] A polarizing plate with a phase difference layer was obtained in the same manner as in Example 3, except that the phase difference film was prepared using only ester resin B from Production Example 2, instead of ethyl cellulose as the resin material. The phase difference film was subjected to the above-mentioned measurement of phase difference values ​​and observation of nanophase separation structure, and the polarizing plate with a phase difference layer was subjected to the above-mentioned HAST test. The results are shown in Table 1.

[0085] [Comparative Example 4] Ethyl cellulose and ester resin A obtained in Production Example 1 were dissolved in a mixed solvent of ethyl acetate / toluene in a 6:4 ratio in a mass ratio of 80:20 to obtain a resin solution with a solid content of 16% by mass. Next, the resin solution was stirred in a disper mixer for 30 minutes, and then allowed to stand for 2 hours to remove air bubbles. The degassed resin solution was then applied using an applicator onto a polyethylene terephthalate (PET) film (Toyobo Co., Ltd., Cosmoshine A4610) to a wet thickness of approximately 810 μm. Next, the coating was dried in an oven under four conditions: 40°C / 4 minutes, 85°C / 4 minutes, 135°C / 4 minutes, and 155°C / 6 minutes, to form a resin film with a thickness of 110 μm on the PET film. Next, the resin film was peeled from the PET film. After peeling, the resin film was preheated at 165°C for 1 minute, and then stretched 2.4 times at a fixed end transversely at a stretching temperature of 155°C and a stretching speed of 2 mm / second. Subsequently, the stretched resin film was shrunk by 2% in the width direction at the same temperature as the stretching temperature (shrinkage temperature 155°C) to obtain a phase difference film with a thickness of 46 μm. This phase difference film was subjected to the measurement of the phase difference value and observation of the nanophase separation structure described above. The results are shown in Table 1. In Comparative Example 4, the TEM cross-sectional image obtained in the observation of the nanophase separation structure showed that each domain of the phase separation was large, more than 100 nm, indicating that a sufficient phase separation state was not obtained. <<Fabrication of polarizing plates with phase difference layer>> Next, a phase difference film was attached to the polarizer of the polarizer plate obtained in Manufacturing Example 3 using a (meth)acrylic adhesive. The thickness of the adhesive layer was 5 μm. The bonding was performed so that the angle between the absorption axis direction of the polarizer and the slow phase axis direction of the phase difference film was as shown in Table 1. Subsequently, a (meth)acrylic adhesive was applied to the phase difference film to form an adhesive layer. The thickness of the adhesive layer was 15 μm. A polarizing plate with a phase difference layer was obtained as described above. The polarizing plate with a phase difference layer was subjected to the HAST test described above. The results are shown in Table 1. The polarizing plate with a phase difference layer of Comparative Example 4 developed cracks after the HAST test.

[0086] [Comparative Example 5] Ethyl cellulose and ester resin A obtained in Production Example 1 were dissolved in a mixed solvent of ethyl acetate / toluene in a 6:4 ratio in a mass ratio of 80:20 to obtain a resin solution with a solid content of 16% by mass. Next, the resin solution was stirred in a disper mixer for 30 minutes, and then allowed to stand for 2 hours to remove air bubbles. The degassed resin solution was then applied using an applicator onto a polyethylene terephthalate (PET) film (Toyobo Co., Ltd., Cosmoshine A4610) to a wet thickness of approximately 810 μm. Next, the coating was dried in an oven under four conditions: 40°C / 10 minutes, 85°C / 4 minutes, 135°C / 4 minutes, and 155°C / 10 minutes, to form a resin film with a thickness of 110 μm on the PET film. Next, the resin film was peeled from the PET film. After peeling, the resin film was preheated at 165°C for 1 minute, and then stretched 2.4 times at a fixed end transversely at a stretching temperature of 155°C and a stretching speed of 2 mm / second. Subsequently, the stretched resin film was shrunk by 2% in the width direction at the same temperature as the stretching temperature (shrinkage temperature 155°C) to obtain a phase difference film with a thickness of 46 μm. This phase difference film was subjected to the measurement of the phase difference value and observation of the nanophase separation structure described above. The results are shown in Table 1. In Comparative Example 5, sufficient properties as a λ / 4 plate could not be secured. In the TEM cross-sectional image obtained in the observation of the nanophase separation structure described above, each domain of the phase separation was around 100 nm, and domains smaller than 100 nm and domains larger than 100 nm were mixed. Therefore, it was found that a suitable nanophase separation structure was not formed. <<Fabrication of polarizing plates with phase difference layer>> Next, a phase difference film was attached to the polarizer of the polarizer plate obtained in Manufacturing Example 3 using a (meth)acrylic adhesive. The thickness of the adhesive layer was 5 μm. The bonding was performed so that the angle between the absorption axis direction of the polarizer and the slow phase axis direction of the phase difference film was as shown in Table 1. Subsequently, a (meth)acrylic adhesive was applied to the phase difference film to form an adhesive layer. The thickness of the adhesive layer was 15 μm. Based on the above, a polarizing plate with a phase difference layer was obtained. The polarizing plate with a phase difference layer of Comparative Example 5 did not have sufficient characteristics as a circular polarizing plate, so a HAST test would not normally be performed, but it was subjected to the HAST test described above as a precaution. The results are shown in Table 1. There were no problems with the appearance of the polarizing plate with a phase difference layer of Comparative Example 5 after the HAST test.

[0087] [Comparative Example 6] A polarizing plate with a phase difference layer was obtained in the same manner as in Comparative Example 1, except that the film thickness after stretching was different. The thickness of the phase difference film was 37 μm. The phase difference film was subjected to the above-mentioned phase difference value measurement, observation of the nanophase separation structure, and MIT test, and the polarizing plate with a phase difference layer was subjected to the above-mentioned HAST test and MIT test. The results are shown in Table 2.

[0088] [Comparative Example 7] <<Preparation of Phase Contrast Film>> A liquid crystal composition (coating solution) was prepared by dissolving 10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (BASF: trade name "Paliocolor LC242", represented by the following formula) and 3 g of a photopolymerization initiator for the polymerizable liquid crystal compound (BASF: trade name "Irgacure 907") in 40 g of toluene. [ka] The surface of a polyethylene terephthalate (PET) film (38 μm thick) was rubbed using a rubbing cloth to perform an orientation treatment. The orientation direction was set so that, when bonded to a polarizing plate, it was 15° from the viewing side relative to the direction of the polarizer's absorption axis. The liquid crystal coating solution was applied to this orientation-treated surface using a bar coater and heated and dried at 90°C for 2 minutes to orient the liquid crystal compound. The liquid crystal layer thus formed was subjected to a 1 mJ / cm³ treatment using a metal halide lamp. 2 A liquid crystal alignment solidified layer was formed on a PET film by irradiating it with light and curing the liquid crystal layer. The liquid crystal alignment solidified layer had a refractive index of nx>ny=nz. The thickness of the liquid crystal alignment solidified layer was 1 μm, and the in-plane phase difference Re(550) was 140 nm. The liquid crystal alignment solidified layer was used as a phase difference film, and this phase difference film was subjected to phase difference value measurement, observation of nanophase separation structure, and MIT testing. The results are shown in Table 2. <<Fabrication of polarizing plates with phase difference layer>> Next, a phase difference film was attached to the polarizer of the polarizer plate obtained in Manufacturing Example 3 using a (meth)acrylic adhesive. The thickness of the adhesive layer was 5 μm. The bonding was performed so that the angle between the absorption axis direction of the polarizer and the slow phase axis direction of the phase difference film was 45°. Subsequently, a (meth)acrylic adhesive was applied to the phase difference film to form an adhesive layer. The thickness of the adhesive layer was 15 μm. A polarizing plate with a phase difference layer was obtained. The polarizing plate with a phase difference layer was subjected to the HAST test and MIT test described above. The results are shown in Table 2.

[0089] [Table 1]

[0090] [Table 2]

[0091] [evaluation] As is clear from Tables 1 and 2, when the phase difference layer contains a cellulose resin and an ester resin, and these constitute a suitable nanophase separation structure, it is possible to realize a polarizing plate with a phase difference layer that maintains the inverse dispersion properties of the phase difference layer while suppressing the occurrence of appearance defects in high-temperature and high-humidity environments. Furthermore, when a nanophase separation structure is formed in the phase difference layer (phase difference film), it is possible to improve the flexibility of the phase difference film and the polarizing plate with a phase difference layer in the stretching direction (MD direction) and in the direction perpendicular to the stretching direction (TD direction). [Industrial applicability]

[0092] The polarizing plate with a phase difference layer according to the embodiment of the present invention can be suitably applied to image display devices (typically liquid crystal display devices and organic EL display devices). [Explanation of symbols]

[0093] 10 Polarizing plates 11 Polarizer 20 Retardation layer 30 Adhesive layer 40 Adhesive layer 50 Release Liner 100 Polarizing plate with retardation layer

Claims

1. A polarizer; A retardation layer containing a cellulose-based resin and an ester-based resin in this order, Re(450) / Re(550) of the retardation layer is 0 to 1, Re(550) of the retardation layer is 100 nm to 200 nm, an angle between an absorption axis direction of the polarizer and a slow axis direction of the retardation layer is 40° to 50°, or 130° to 140°; A polarizing plate with a retardation layer, wherein a nano-phase separation structure is formed in the retardation layer.

2. The retardation layer-attached polarizing plate according to claim 1, wherein the cellulose-based resin has a structural unit represented by the following formula (1): 【Chemistry 1】 (In formula (1), R １ ~R ３ Each of represents a hydrogen atom or a substituent having 1 to 12 carbon atoms.

3. The retardation layer-attached polarizing plate according to claim 1 or 2, wherein the ester resin has a structural unit represented by the following formula (2) and a structural unit represented by the following formula (3): 【Chemistry 2】 (In formula (2), R ４ represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms; R ５ａ represents one selected from an alkyl group having 1 to 12 carbon atoms, a nitro group, a bromo group, an iodo group, a cyano group, a chloro group, a sulfonic acid group, a carboxylic acid group, a fluoro group, and a thiol group; R ５ｂ represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms; R ６ represents one selected from a hydrogen atom, a nitro group, a bromo group, an iodo group, a cyano group, a chloro group, a sulfonic acid group, a carboxylic acid group, a fluoro group, a phenyl group, a thiol group, an amido group, an amino group, a hydroxyl group, an alkoxy group having 1 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms. 【Chemistry 3】 (In formula (3), R ７ represents a 5-membered or 6-membered heterocyclic residue containing one or more nitrogen or oxygen atoms as heteroatoms (the 5-membered and 6-membered heterocyclic residues may form a condensed ring structure with another ring structure).

4. The retardation layer-attached polarizing plate according to claim 3, wherein the ester resin further has a structural unit represented by the following formula (4): 【Chemistry 4】 (In formula (4), R ８ and R ９ Each of represents one selected from a hydrogen atom, a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 3 to 12 carbon atoms, and a cyclic alkyl group having 3 to 6 carbon atoms.

5. 3. The retardation layer-attached polarizing plate according to claim 1, wherein a content of the cellulose-based resin exceeds 50% by mass when a total content of the cellulose-based resin and the ester-based resin is taken as 100% by mass.

6. the retardation layer is a stretched film obtained by stretching a resin film containing a cellulose-based resin and an ester-based resin, 3. The polarizing plate with a retardation layer according to claim 1, wherein the number of MIT cycles in a direction perpendicular to the stretching direction of the stretched film is 300 or more.

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