TWI869619B - Dyed triacetate cellulose film, polarizing plate using the film, method for manufacturing the polarizing plate, polarizing plate with phase difference layer, image display device, and image adjustment method for the image display device - Google Patents

Abstract

The present invention provides a polarizing plate and a polarizing plate with a phase difference layer that can achieve a neutral reflection hue when applied to an image display device. The polarizing plate of the present invention comprises a polarizing film and a protective layer disposed on the visual side of the polarizing film. The thickness of the polarizing film is less than 8µm; the protective layer is composed of a cellulose triacetate film dyed with iodine, and the transmittance of the protective layer at a wavelength of 400nm is less than 65%. The polarizing plate with a phase difference layer of the present invention comprises the above-mentioned polarizing plate and a phase difference layer disposed on the side of the polarizing plate opposite to the visual side. The Re(550) of the phase difference layer is 100nm~190nm, and the Re(450)/Re(550) is greater than 0.8 and less than 1; the angle formed by the slow axis of the phase difference layer and the absorption axis of the polarizing film of the polarizing plate is 40°~50°.

Description

Dyed triacetate cellulose film, polarizing plate using the film, method for manufacturing polarizing plate, polarizing plate with phase difference layer, image display device, and image adjustment method of image display device

The present invention relates to a dyed triacetate cellulose film, a polarizing plate using the film, a method for manufacturing the polarizing plate, a polarizing plate with a phase difference layer, an image display device, and an image adjustment method for the image display device.

In recent years, image display devices represented by liquid crystal display devices and electroluminescent (EL) display devices (such as organic EL display devices and inorganic EL display devices) have rapidly become popular. Image display devices typically use polarizing plates and phase difference plates. In practical applications, polarizing plates with phase difference layers that are integrated with polarizing plates and phase difference plates are widely used (such as patent document 1). Recently, with the increasing demand for thinner image display devices, the demand for thinner polarizing plates and polarizing plates with phase difference layers has also increased. One of the means to thin polarizing plates and polarizing plates with phase difference layers is to thin polarizing films. However, when polarizing plates containing thin polarizing films or polarizing plates with phase difference layers are used in image display devices, there is a problem that the reflected hue is bluish. Prior art literature Patent literature

Patent document 1: Japanese Patent No. 3325560

Problem to be solved by the invention The present invention is made to solve the above-mentioned previous problems. Its main purpose is to provide a polarizing plate and a polarizing plate with a phase difference layer that can achieve a neutral reflection hue when used in an image display device, and a dyed triacetate cellulose film that can achieve the above-mentioned polarizing plate and polarizing plate with a phase difference layer.

Means for solving the problem The dyed triacetate cellulose film of the embodiment of the present invention has been iodine-dyed, and the transmittance at a wavelength of 400nm is less than 65%, and the transmittance Y after visual sensitivity correction is more than 80%. According to another aspect of the present invention, a polarizing plate is provided. The polarizing plate includes a polarizing film and a protective layer disposed on at least one side of the polarizing film. The thickness of the polarizing film is less than 8µm, and the protective layer is composed of the above-mentioned dyed triacetate cellulose film. According to another aspect of the present invention, a method for manufacturing the above-mentioned polarizing plate is provided. The manufacturing method comprises the following steps: forming a polyvinyl alcohol resin layer on one side of a long thermoplastic resin substrate to form a laminate; performing dyeing and stretching treatment on the laminate to make the polyvinyl alcohol resin layer into a polarizing film; dyeing a cellulose triacetate film with iodine so that its transmittance at a wavelength of 400nm is less than 65% and the transmittance Y after visual sensitivity correction is more than 80%; and laminating the dyed cellulose triacetate film to the polarizing film. In one embodiment, the dyeing comprises immersing the cellulose triacetate film in an iodine aqueous solution having an iodine concentration of more than 0.1% by weight. According to another aspect of the present invention, a polarizing plate with a phase difference layer is provided. The polarizing plate with phase difference layer comprises the above-mentioned polarizing plate and the phase difference layer arranged on the side of the polarizing plate opposite to the visual side. The Re(550) of the phase difference layer is 100nm~190nm, and the Re(450)/Re(550) is greater than 0.8 and less than 1; the angle formed by the slow axis of the phase difference layer and the absorption axis of the polarizing film of the polarizing plate is 40°~50°. In one embodiment, the above-mentioned phase difference layer is composed of a polycarbonate resin film. In one embodiment, the polarizing plate with phase difference layer has another phase difference layer outside the above-mentioned phase difference layer, and the refractive index characteristics of the other phase difference layer show the relationship of nz＞nx=ny. In one embodiment, the polarizing plate with a phase difference layer is in the shape of a long strip, the polarizing film has an absorption axis in the direction of the long strip, and the phase difference layer is an obliquely stretched film having a slow axis in a direction forming an angle of 40° to 50° relative to the direction of the long strip. In one embodiment, the polarizing plate with a phase difference layer can be rolled into a roll. The polarizing plate with a phase difference layer in another embodiment of the present invention includes the polarizing plate and the phase difference layer arranged on the side of the polarizing plate opposite to the visual recognition side. The phase difference layer has a laminated structure of a first liquid crystal compound directional solidification layer and a second liquid crystal compound directional solidification layer. The Re(550) of the oriented solidified layer of the first liquid crystal compound is 200nm~300nm, and the angle formed by its slow axis and the absorption axis of the above-mentioned polarizing film is 10°~20°; the Re(550) of the oriented solidified layer of the second liquid crystal compound is 100nm~190nm, and the angle formed by its slow axis and the absorption axis of the above-mentioned polarizing film is 70°~80°. In one embodiment, the above-mentioned polarizing plate with a phase difference layer further has a conductive layer or an isotropic substrate with a conductive layer outside the above-mentioned phase difference layer. According to another aspect of the present invention, an image display device is provided. The image display device has the above-mentioned polarizing plate or the polarizing plate with a phase difference layer. In one embodiment, the image display device is an organic electroluminescent display device or an inorganic electroluminescent display device. According to another aspect of the present invention, a method for adjusting an image of an image display device is provided. The method comprises the following steps: attaching the polarizing plate or the polarizing plate with a phase difference layer to the visual side of the image display unit to make the reflected hue close to neutral.

Effect of the invention According to the present invention, by using an iodine-dyed cellulose triacetate film having a predetermined transmittance at a predetermined wavelength and a predetermined transmittance Y after visual sensitivity correction as a protective layer of a polarizing film, a polarizing plate and a polarizing plate with a phase difference layer that can achieve a neutral reflection hue when used in an image display device can be realized.

The following describes the implementation forms of the present invention, but the present invention is not limited to these implementation forms.

(Definition of terms and symbols) The definitions of terms and symbols in this manual are as follows. (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction where the in-plane refractive index reaches the maximum (i.e., the slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis (i.e., the fast 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 at 23°C with light of wavelength λnm. For example, "Re(550)" is the in-plane phase difference measured at 23°C with light of wavelength 550nm. Re(λ) can be calculated by the formula: Re(λ)=(nx-ny)×d when the thickness of the layer (film) is d(nm). (3) Retardation in the thickness direction (Rth) "Rth(λ)" is the phase difference in the thickness direction measured at 23°C with light of wavelength λnm. For example, "Rth(550)" is the phase difference in the thickness direction measured at 23°C with light of wavelength 550nm. Rth(λ) can be calculated by the formula: Rth(λ)=(nx-nz)×d when the thickness of the layer (film) is d(nm). (4) Nz coefficient The Nz coefficient can be calculated by Nz=Rth/Re. (5) Angle When an angle is mentioned in this manual, the angle includes both the clockwise direction and the counterclockwise direction relative to the reference direction. Therefore, for example, "45°" means ±45°.

A. Polarizing plate According to an embodiment of the present invention, a triacetate cellulose (TAC) film that has been dyed with iodine is provided. The transmittance of the dyed TAC film at a wavelength of 400nm is less than 65%, and the transmittance Y (hereinafter sometimes referred to as Y-value transmittance) after correction of visual sensitivity is more than 80%. The dyed TAC film can be suitably used as a protective layer of a polarizing plate. The polarizing plate of the embodiment of the present invention includes a polarizing film and a protective layer disposed on at least one side of the polarizing film. That is, the protective layer can be disposed on both sides of the polarizing film, can be disposed only on the visual side of the polarizing film, or can be disposed only on the side of the polarizing film opposite to the visual side. In the embodiment of the present invention, at least one of the protective layers is composed of a dyed TAC film. According to one embodiment, in a polarizing plate having a visual side protective layer/polarizing film structure, the visual side protective layer is formed of a dyed TAC film.

A-1. Polarizing film The polarizing film is typically made of a polyvinyl alcohol (PVA) resin film containing iodine. The thickness of the polarizing film is typically 8µm or less, preferably 7µm or less, more preferably 5µm or less, and even more preferably 3µm or less. The lower limit of the thickness of the polarizing film may be 1µm in one embodiment and 2µm in another embodiment.

The polarizing film preferably shows absorption dichroism at any wavelength between 380nm and 780nm. The monomer transmittance of the polarizing film should be above 42.0%, preferably above 42.5%, and more preferably above 43.0%. On the other hand, the monomer transmittance should be below 47.0%, and preferably below 46.0%. The polarization degree of the polarizing film should be above 99.95%, preferably above 99.99%. On the other hand, the polarization degree should be below 99.998%. The polarizing film used in the embodiment of the present invention can have both high monomer transmittance and high polarization degree as described above. The above-mentioned monomer transmittance is typically the Y value obtained by measuring with an ultraviolet-visible spectrophotometer and performing visual sensitivity correction. In addition, the single transmittance is the value when the refractive index of one surface of the polarizing plate is converted to 1.50 and the refractive index of the other surface is converted to 1.53. The above polarization degree is calculated based on the parallel transmittance Tp and the orthogonal transmittance Tc obtained by measuring and correcting the visual sensitivity using an ultraviolet visible light spectrophotometer. Polarization degree (%) = {(Tp-Tc)/(Tp+Tc)} ^{1 /2} ×100

In one embodiment, the transmittance of a thin polarizing film of less than 8µm is measured using a UV-visible spectrophotometer using a layered product of a polarizing film (refractive index of the surface: 1.53) and a protective film (refractive index: 1.50). The reflectivity at the interface of each layer changes depending on the refractive index of the polarizing film surface and/or the refractive index of the surface of the protective film in contact with the air interface, resulting in changes in the measured value of the transmittance. Therefore, for example, when a protective film with a refractive index other than 1.50 is used, the measured value of the transmittance can also be corrected according to the refractive index of the surface of the protective film in contact with the air interface. Specifically, the corrected value C of the transmittance is expressed by the following formula using the reflectivity R ₁ (transmission axis reflectivity) of polarized light parallel to the transmission axis at the interface between the protective film and the air layer. C=R ₁ -R ₀ R ₀ =((1.50-1) ² /(1.50+1) ² )×(T ₁ /100) R ₁ =((n ₁ -1) ² /(n ₁ +1) ² )×(T ₁ /100) Here, R ₀ is the transmission axis reflectance when a protective film with a refractive index of 1.50 is used, n ₁ is the refractive index of the protective film used, and T ₁ is the transmittance of the polarizing film. For example, when a substrate (cycloolefin film, film with hard coating, etc.) with a surface refractive index of 1.53 is used as the protective film, the correction amount C is about 0.2%. At this time, by adding 0.2% to the measured transmittance, the polarizing film with a surface refractive index of 1.53 can be converted into the transmittance when a protective film with a refractive index of 1.50 is used. In addition, according to the above formula, the change in the correction value C after changing the transmittance _T1 of the polarizing film by 2% is less than 0.03%, so the influence of the transmittance of the polarizing film on the correction value C is limited. In addition, when the protective film has absorption other than surface reflection, appropriate correction can be performed according to the absorption amount.

Polarizing film can be made of a single resin film or a laminate of two or more layers.

A specific example of a polarizing film obtained using a laminate is a polarizing film obtained using a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate by coating. A polarizing film obtained using a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate by coating can be produced, for example, by: coating a PVA-based resin solution on a resin substrate, and drying the PVA-based resin layer on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; and, extending and dyeing the laminate to produce a polarizing film from the PVA-based resin layer. In this embodiment, the stretching typically includes immersing the laminate in a boric acid aqueous solution and stretching it. Optionally, the stretching may further include stretching the laminate in the air at a high temperature (e.g., above 95° C.) before stretching it in the boric acid aqueous solution.

In more detail, the manufacturing method of the polarizing film includes the following steps: forming a polyvinyl alcohol resin layer containing a halogenated substance and a polyvinyl alcohol resin on one side of a long thermoplastic resin substrate to form a laminate; and sequentially performing an air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying and shrinking treatment on the laminate, wherein the drying and shrinking treatment is to heat the laminate while conveying the laminate along the long side direction, thereby shrinking the laminate by more than 2% in the width direction. Thus, a polarizing film with a thickness of less than 8µm and excellent optical properties can be provided. That is, by introducing auxiliary stretching, the crystallinity of PVA can be improved even when PVA is coated on a thermoplastic resin, and high optical properties can be achieved. In addition, by improving the orientation of PVA in advance, it is possible to prevent the orientation of PVA from being reduced or dissolved when immersed in water in the subsequent dyeing step or stretching step, and high optical properties can be achieved. Moreover, when the PVA-based resin layer is immersed in a liquid, the orientation disorder of the polyvinyl alcohol molecules and the reduction of orientation can be suppressed compared to the case where the PVA-based resin layer does not contain halides. In this way, the optical properties of the polarizing film obtained by the treatment steps of immersing the laminate in a liquid such as dyeing treatment and underwater stretching treatment can be improved. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction through a drying and shrinking process. The details of the manufacturing method of the polarizing film will be described in Section B.

A-2. Protective layer As described above, in an embodiment of the present invention, at least one of the protective layer disposed on the visual side (hereinafter referred to as the visual side protective layer) and the protective layer disposed on the side opposite to the visual side (hereinafter referred to as the inner side protective layer) is formed of a dyed TAC film. From the perspective of thinning and lightening the polarizing plate, the inner side protective layer can be appropriately omitted. Therefore, according to one embodiment, in a polarizing plate having a visual side protective layer/polarizing film structure, the visual side protective layer is formed of a dyed TAC film. By using a dyed TAC film for the visual side protective layer and/or the inner side protective layer, even when a thin polarizing film (e.g., thickness below 8µm) is used, the reflected hue of the image display device can be prevented from being bluish, resulting in a very excellent (neutral) reflected hue.

When a visual side protective layer and an inner side protective layer are provided and only one of them is formed of a dyed TAC film, the other protective layer is formed of any appropriate film that can be used as a protective layer of a polarizing film. Specific examples of the material that is the main component of the film include cellulose resins such as triacetate cellulose (TAC), or polyester, polyvinyl alcohol, polycarbonate, polyamide, polyimide, polyether sulfone, polysulfone, polystyrene, polynorbornene, polyolefin, (meth)acrylic acid, and acetate transparent resins. In addition, thermosetting resins or ultraviolet curing resins such as (meth) acrylic acid, urethane, (meth) acrylic urethane, epoxy, and silicone can also be cited. Other examples include glassy polymers such as silicone polymers. In addition, the polymer film described in Japanese Patent Publication No. 2001-343529 (WO01/37007) can also be used. As the material of the film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted amide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl and nitrile group in the side chain can be used, and for example, a resin composition having an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be cited. The polymer film may be, for example, an extruded product of the above-mentioned resin composition.

The transmittance of the dyed TAC film at a wavelength of 400nm is less than 65%, preferably less than 60%, more preferably less than 55%, more preferably less than 40%, and particularly preferably less than 35%. The lower limit of the transmittance may be, for example, 0.1%. If the transmittance is within the range, the reflection hue can be more excellent. In addition, the Y value transmittance of the dyed TAC film is more than 80%, preferably more than 85%, and more preferably more than 90%. The higher the Y value transmittance, the better. The upper limit of the Y value transmittance may be, for example, 98%. One of the characteristics of the dyed TAC film is that the transmittance at a wavelength of 400nm will be significantly reduced, while on the other hand, the Y value transmittance can maintain a high value.

The above-mentioned effect brought by the dyed TAC film is presumably due to the following mechanism: the iodine content (absolute amount) of the thin polarizing film is small. The polarizing film of the embodiment of the present invention is manufactured by the method described in item B below. Even if the iodine content (absolute amount) is small, the total amount of I ₅ ^-ions and I ₃ ^-ions that become the source of PVA-I ₅ ^-complex and PVA-I ₃ ^-complex that contribute to the absorption of visible light can be maintained within the desired range, so that the single body transmittance and polarization degree can be maintained at a high level despite the thinness. Nevertheless, the thin polarizing film has a tendency to reduce the absorption of short-wavelength (e.g., below 400nm) light due to the small iodine content (absolute amount). According to the implementation form of the present invention, by using a dyed TAC film as a protective layer, the protective layer can absorb short-wavelength light. As a result, the polarizing plate as a whole can fully absorb short-wavelength light, thereby making up for the short-wavelength absorption of the thin polarizing film. As a result, the excellent characteristics of the thin polarizing film used in the implementation form of the present invention can be maintained, and at the same time, the reflection hue of the image display device can be prevented from being bluish, and a very excellent (neutral) reflection hue can be achieved. In addition, if the thin polarizing film contains too much iodine, PVA-iodine complex will be formed, so the Y value transmittance will also be reduced at the same time. On the other hand, iodine will not complex in the TAC film, so the absorption of iodine is not limited to short wavelengths, and the short-wavelength transmittance can be suppressed while maintaining the Y value transmittance.

The visual side protection layer may also be subjected to surface treatments such as hard coating, anti-reflection treatment, anti-adhesion treatment, and anti-glare treatment as required. In addition, or alternatively, the visual side protection layer may be subjected to treatments useful for improving visibility when viewed through polarized sunglasses (typically, imparting (elliptical) circular polarization function and imparting ultra-high phase difference) as required. By performing the above treatments, even when viewing the display screen through polarized lenses such as polarized sunglasses, excellent visibility can still be achieved. Therefore, the polarizing plate or the polarizing plate with a phase difference layer can also be suitably used in image display devices that can be used outdoors.

The thickness of the visual side protective layer is preferably 5µm~80µm, more preferably 10µm~40µm, and even more preferably 10µm~35µm. In addition, when surface treatment is applied, the thickness of the visual side protective layer includes the thickness of the surface treatment layer.

In one embodiment, the inner protective layer is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane phase difference Re(550) is 0nm~10nm, and the phase difference Rth(550) in the thickness direction is -10nm~+10nm. In one embodiment, the inner protective layer can be a phase difference layer with any appropriate phase difference value. At this time, the in-plane phase difference Re(550) of the phase difference layer is, for example, 110nm~150nm. The thickness of the inner protective layer is preferably 5µm~80µm, more preferably 10µm~40µm, and more preferably 10µm~30µm. As mentioned above, from the perspective of thinning and weight reduction, the inner protective layer can be omitted.

B. Manufacturing method of polarizing plate B-1. Manufacturing method of polarizing film Polarizing film can be obtained, for example, by a manufacturing method comprising the following steps: forming a polyvinyl alcohol resin layer (PVA resin layer) containing a halogenated substance and a polyvinyl alcohol resin (PVA resin) on one side of a long strip of thermoplastic resin substrate to form a laminate; and sequentially subjecting the laminate to air-assisted stretching treatment, dyeing treatment, underwater stretching treatment and drying shrinkage treatment, wherein the drying shrinkage treatment is to heat the laminate while conveying it in the longitudinal direction, thereby shrinking it by more than 2% in the width direction. The content of the halogenated substance in the PVA resin layer is preferably 5 to 20 parts by weight relative to 100 parts by weight of the PVA resin. The drying and shrinking treatment is preferably carried out using a heating roller, and the temperature of the heating roller is preferably 60°C to 120°C. The shrinkage rate of the laminate in the width direction during the drying and shrinking treatment is preferably 2% or more. According to the manufacturing method, the polarizing film described in the above-mentioned item A-1 can be obtained. In particular, a polarizing film with excellent optical properties (represented by single body transmittance and polarization degree) can be obtained by the following method: after preparing a laminate including a halogenated PVA resin layer, the laminate is stretched by a multi-stage stretching process including air-assisted stretching and underwater stretching, and the stretched laminate is then heated by a heating roller.

B-1-1. Preparation of laminate The method of preparing the laminate of the thermoplastic resin substrate and the PVA resin layer can adopt any appropriate method. It is preferable to apply a coating liquid containing a halogen and a PVA resin on the surface of the thermoplastic resin substrate and dry it, thereby forming a PVA resin layer on the thermoplastic resin substrate. As mentioned above, the content of the halogen in the PVA resin layer is preferably 5 to 20 parts by weight relative to 100 parts by weight of the PVA resin.

The coating liquid can be applied by any appropriate method, such as roller coating, spin coating, wire rod coating, dip coating, die coating, curtain coating, spray coating, scraper coating (corner wheel coating, etc.). The coating and drying temperature of the coating liquid is preferably above 50°C.

The thickness of the PVA resin layer is preferably 3µm~40µm, more preferably 3µm~20µm.

Before forming the PVA resin layer, the thermoplastic resin substrate may be subjected to surface treatment (e.g., corona treatment), or an easy-adhesion layer may be formed on the thermoplastic resin substrate. By performing the above treatment, the adhesion between the thermoplastic resin substrate and the PVA resin layer may be improved.

B-1-1-1. Thermoplastic resin substrate The thermoplastic resin substrate may be any appropriate thermoplastic resin film. Details of the thermoplastic resin film substrate are described, for example, in Japanese Patent Publication No. 2012-73580 or Japanese Patent No. 6470455. The entire contents of these publications are cited in this specification for reference.

B-1-1-2. Coating liquid The coating liquid contains the halogenated substance and the PVA resin as described above. The coating liquid is typically a solution obtained by dissolving the halogenated substance and the PVA resin in a solvent. Examples of the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyols such as trihydroxymethylpropane, and amines such as ethylenediamine and diethylenetriamine. These can be used alone or in combination of two or more. Of these, water is preferred. The PVA resin concentration of the solution is preferably 3 to 20 parts by weight relative to 100 parts by weight of the solvent. If the resin concentration is as described above, a uniform coating film can be formed that is closely attached to the thermoplastic resin substrate. The content of the halogen in the coating liquid is preferably 5 to 20 parts by weight relative to 100 parts by weight of the PVA resin.

Additives may also be mixed into the coating liquid. Examples of additives include plasticizers and surfactants. Examples of plasticizers include polyols such as ethylene glycol and glycerol. Examples of surfactants include non-ionic surfactants. These may be used to further enhance the uniformity, dyeability, and elongation of the resulting PVA-based resin layer.

The PVA resin may be any appropriate resin. The details of the PVA resin are described in, for example, Japanese Patent Publication No. 2012-73580 or Japanese Patent No. 6470455 (mentioned above).

The above-mentioned halides may be any appropriate halides. Examples thereof include iodides and sodium chloride. Examples of iodides include potassium iodide, sodium iodide and lithium iodide. Among these, potassium iodide is preferred.

The amount of the halogenated substance in the coating liquid is preferably 5 to 20 parts by weight relative to 100 parts by weight of the PVA resin, and more preferably 10 to 15 parts by weight relative to 100 parts by weight of the PVA resin. If the amount of the halogenated substance is greater than 20 parts by weight relative to 100 parts by weight of the PVA resin, the halogenated substance may overflow and the polarizing film obtained may become white and turbid.

Generally speaking, after the PVA resin layer is stretched, the orientation of the polyvinyl alcohol molecules in the PVA resin layer will become higher. However, if the stretched PVA resin layer is immersed in a water-containing liquid, the orientation of the polyvinyl alcohol molecules will be disordered and the orientation will be reduced. In particular, when the laminate of the thermoplastic resin substrate and the PVA resin layer is stretched in boric acid water at a relatively high temperature in order to stabilize the stretching of the thermoplastic resin substrate, the tendency of the above orientation to be reduced is very obvious. For example, the stretching of a PVA film monomer in boric acid water is generally carried out at 60°C. In contrast, the stretching of a laminate of A-PET (thermoplastic resin substrate) and a PVA-based resin layer is carried out at a relatively high temperature of around 70°C. At this time, the orientation of the PVA at the beginning of the stretching decreases before it rises by stretching in water. In contrast, by preparing a laminate of a halogenated PVA-based resin layer and a thermoplastic resin substrate, and stretching the laminate at a high temperature in air (auxiliary stretching) before stretching in boric acid water, the crystallization of the PVA-based resin in the PVA-based resin layer of the laminate after auxiliary stretching can be promoted. As a result, when the PVA resin layer is immersed in a liquid, the orientation disorder and the reduction of orientation of the polyvinyl alcohol molecules can be suppressed more than when the PVA resin layer does not contain halides. As a result, the optical properties of the polarizing film obtained by immersing the laminate in a liquid through dyeing treatment and underwater stretching treatment can be improved.

B-1-2. Auxiliary stretching in the air In order to obtain high optical properties, a two-stage stretching method combining dry stretching (auxiliary stretching) and stretching in boric acid water is selected. In the two-stage stretching method, by introducing auxiliary stretching, the crystallization of the thermoplastic resin substrate can be suppressed while stretching, solving the problem of reduced stretchability due to excessive crystallization of the thermoplastic resin substrate in the subsequent boric acid water stretching, and the laminate can be stretched at a higher magnification. Furthermore, when coating PVA resin on a thermoplastic resin substrate, in order to suppress the influence of the glass transition temperature of the thermoplastic resin substrate, the coating temperature must be lower than when coating PVA resin on a general metal roller, resulting in a problem that the crystallization of PVA resin becomes relatively low and sufficient optical properties cannot be obtained. In response to this, by introducing auxiliary stretching, the crystallization of PVA resin can be improved even when coating PVA resin on a thermoplastic resin, thereby achieving high optical properties. In addition, by improving the orientation of the PVA resin in advance, it is possible to prevent the orientation of the PVA resin from being reduced or dissolved when immersed in water in the subsequent dyeing or stretching steps, thereby achieving high optical properties.

The stretching method of aerial assisted stretching can be fixed-end stretching (for example, a method of stretching using a tenter stretching machine) or free-end stretching (for example, a method of uniaxially stretching the laminate by passing it between rollers with different circumferential speeds). However, in order to obtain high optical properties, free-end stretching can be actively adopted. In one embodiment, the aerial stretching process includes a heating roller stretching step, which is to stretch the laminate while transporting it along its long side direction using the circumferential speed difference between the heating rollers. The aerial stretching process typically includes a zone stretching step and a heating roller stretching step. In addition, the order of the zone stretching step and the heating roller stretching step is not limited, and the zone stretching step can be performed first, or the heating roller stretching step can be performed first. The regional stretching step may also be omitted. In one embodiment, the regional stretching step and the heating roller stretching step are performed in sequence. In another embodiment, the film ends are held in a tenter stretching machine, and the distance between the tenters is expanded in the traveling direction to stretch (the increase in the distance between the tenters is the stretching ratio). At this time, the distance between the tenters in the width direction (vertical to the traveling direction) is set to be arbitrarily close. It is advisable to set the stretching ratio relative to the traveling direction to use the free end stretching for approach. In the case of free end stretching, the shrinkage ratio in the width direction = (1/stretching ratio) ^1/2 is used for calculation.

The air-assisted stretching can be performed in one stage or in multiple stages. When it is performed in multiple stages, the stretching ratio is the product of the stretching ratios of each stage. The stretching direction in the air-assisted stretching is preferably substantially the same as the stretching direction in the underwater stretching.

The stretching ratio of the air-assisted stretching is preferably 2.0 to 3.5 times. The maximum stretching ratio when the air-assisted stretching and the underwater stretching are combined is preferably 5.0 times or more, preferably 5.5 times or more, and more preferably 6.0 times or more relative to the original length of the laminate. The "maximum stretching ratio" in this specification refers to the stretching ratio before the laminate is about to break, which is 0.2 lower than the stretching ratio obtained by separately confirming the fracture of the laminate.

The stretching temperature of the air-assisted stretching can be set to any appropriate value according to the forming material of the thermoplastic resin substrate, the stretching method, etc. The stretching temperature is preferably above the glass transition temperature (Tg) of the thermoplastic resin substrate, more preferably above the glass transition temperature (Tg) of the thermoplastic resin substrate + 10°C, and particularly preferably above Tg + 15°C. On the other hand, the upper limit of the stretching temperature is preferably 170°C. By stretching at the above temperature, the rapid progress of crystallization of the PVA-based resin can be suppressed, and the undesirable conditions caused by the crystallization (for example, the orientation of the PVA-based resin layer is hindered by stretching) can be suppressed. The crystallization index of the PVA-based resin after air-assisted stretching is preferably 1.3~1.8, and more preferably 1.4~1.7. The crystallization index of PVA resin can be measured by Fourier transform infrared spectrophotometer by ATR method. Specifically, polarized light is used as the measuring light for measurement, and the crystallization index is calculated by the following formula using the intensity of 1141cm ^-1 and 1440cm ^-1 of the obtained spectrum. Crystallization index = ( _IC / _IR ) However, _IC : the intensity of 1141cm ^-1 when the measuring light is incident and the measurement is carried out, _IR : the intensity of 1440cm ^-1 when the measuring light is incident and the measurement is carried out.

B-1-3. Insolubilization treatment, dyeing treatment and crosslinking treatment If necessary, after the air-assisted stretching treatment and before the water stretching treatment or dyeing treatment, an insolubilization treatment is performed. The above-mentioned insolubilization treatment is typically performed by immersing the PVA-based resin layer in an aqueous solution of boric acid. The above-mentioned dyeing treatment is typically performed by dyeing the PVA-based resin layer with a dichroic substance (typically iodine). If necessary, after the dyeing treatment and before the water stretching treatment, a crosslinking treatment is performed. The above-mentioned crosslinking treatment can be typically performed by immersing the PVA-based resin layer in an aqueous solution of boric acid. The details of the insolubilization treatment, dyeing treatment and crosslinking treatment are described in, for example, Japanese Patent Publication No. 2012-73580 or Japanese Patent No. 6470455 (mentioned above).

B-1-4. Underwater stretching treatment Underwater stretching treatment is performed by immersing the laminate in a stretching bath. Through underwater stretching treatment, stretching can be performed at a temperature lower than the glass transition temperature of the above-mentioned thermoplastic resin substrate or PVA resin layer (typically around 80°C), and high-ratio stretching can be performed while suppressing the crystallization of the PVA resin layer. As a result, a polarizing film with excellent optical properties can be produced.

The lamination body may be stretched by any appropriate method. Specifically, it may be fixed-end stretching or free-end stretching (for example, a method of uniaxial stretching of the lamination body by passing it between rollers with different circumferential speeds). Free-end stretching is preferred. The lamination body may be stretched in one stage or in multiple stages. When stretched in multiple stages, the stretching ratio (maximum stretching ratio) of the lamination body described below is the product of the stretching ratios of each stage.

It is advisable to immerse the laminate in a boric acid aqueous solution for underwater stretching (boric acid underwater stretching). By using a boric acid aqueous solution as a stretching bath, the PVA resin layer can be given the rigidity to withstand the tension applied during stretching and the water resistance of being insoluble in water. Specifically, boric acid generates tetrahydroxyboric acid anions in an aqueous solution and can crosslink with the PVA resin through hydrogen bonds. As a result, the PVA resin layer can be given rigidity and water resistance, and good stretching can be performed, thereby producing a polarizing film with excellent optical properties.

The boric acid aqueous solution is preferably obtained by dissolving boric acid and/or boric acid salt in water which is a solvent. The boric acid concentration is preferably 1 to 10 parts by weight, more preferably 2.5 to 6 parts by weight, and particularly preferably 3 to 5 parts by weight relative to 100 parts by weight of water. By making the boric acid concentration 1 part by weight or more, the dissolution of the PVA resin layer can be effectively suppressed, and a polarizing film with higher properties can be manufactured. In addition to boric acid or boric acid salt, an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde, etc. in a solvent can also be used.

It is preferable to mix iodide in the stretching bath (boric acid aqueous solution). By mixing iodide, the dissolution of iodine adsorbed on the PVA resin layer can be suppressed. The specific example of iodide is as mentioned above. The concentration of iodide is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 8 parts by weight, relative to 100 parts by weight of water.

The stretching temperature (liquid temperature of the stretching bath) is preferably 40°C to 85°C, more preferably 60°C to 75°C. If it is the above temperature, the dissolution of the PVA-based resin layer can be suppressed, and at the same time, it can be stretched at a high ratio. Specifically, as mentioned above, in relation to the formation of the PVA-based resin layer, the glass transition temperature (Tg) of the thermoplastic resin substrate is preferably above 60°C. At this time, if the stretching temperature is lower than 40°C, even if the thermoplastic resin substrate is plasticized with water, it may not be stretched well. On the other hand, the higher the temperature of the stretching bath, the higher the solubility of the PVA-based resin layer, and excellent optical properties may not be obtained. The immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.

The stretching ratio of the underwater stretching is preferably 1.5 times or more, preferably 3.0 times or more. The total stretching ratio of the laminate is preferably 5.0 times or more, more preferably 5.5 times or more relative to the original length of the laminate. By achieving the high stretching ratio, a polarizing film with excellent optical properties can be manufactured. The high stretching ratio can be achieved by adopting an underwater stretching method (boric acid underwater stretching).

B-1-5. Drying and shrinking treatment The above-mentioned drying and shrinking treatment can be performed by heating the area as a whole, or by heating the conveying roller (so-called using a heating roller) (heating roller drying method). It is preferred to use both. By using a heating roller to dry it, the heat curling of the laminate can be effectively suppressed, and a polarizing film with excellent appearance can be produced. Specifically, by drying the laminate while passing through the heating roller, the crystallization of the above-mentioned thermoplastic resin substrate can be effectively promoted to increase the crystallinity. Even at a relatively low drying temperature, the crystallinity of the thermoplastic resin substrate can still be well increased. As a result, the rigidity of the thermoplastic resin substrate increases and becomes a state that can withstand the shrinkage of the PVA-based resin layer due to drying, thereby suppressing curling. In addition, by using a heating roller, the laminate can be dried while maintaining a flat state, so that not only curling but also wrinkling can be suppressed. At this time, the laminate can be shrunk in the width direction through a drying and shrinking treatment to improve the optical properties. This is because the orientation of PVA and PVA/iodine complex can be effectively improved. The shrinkage rate of the laminate in the width direction under the drying and shrinking treatment is preferably 1%~10%, more preferably 2%~8%, and particularly preferably 4%~6%. By using heated rollers, the laminate can be continuously shrunk in the width direction while being transported, achieving high productivity.

FIG. 1 is a schematic diagram showing an example of a drying and shrinking process. In the drying and shrinking process, the laminate 200 is dried while being transported by conveying rollers R1 to R6 and guide rollers G1 to G4 that have been heated to a predetermined temperature. In the example of the figure, the conveying rollers R1 to R6 are arranged to alternately and continuously heat the surface of the PVA resin layer and the surface of the thermoplastic resin substrate, but, for example, the conveying rollers R1 to R6 may also be arranged to continuously heat only one surface of the laminate 200 (e.g., the surface of the thermoplastic resin substrate).

The drying conditions can be controlled by adjusting the heating temperature of the conveyor roller (temperature of the heating roller), the number of heating rollers, and the contact time with the heating roller. The temperature of the heating roller is preferably 60°C to 120°C, more preferably 65°C to 100°C, and particularly preferably 70°C to 80°C. While the crystallinity of the thermoplastic resin can be well increased and the curling can be well suppressed, an optical laminate with excellent durability can be produced. In addition, the temperature of the heating roller can be measured by a contact thermometer. In the example of the figure, 6 conveyor rollers are provided, but there is no special restriction if there are multiple conveyor rollers. The number of conveyor rollers is usually 2 to 40, and 4 to 30 are preferably provided. The contact time (total contact time) between the laminate and the heating roller is preferably 1 second to 300 seconds, more preferably 1 to 20 seconds, and even more preferably 1 to 10 seconds.

The heating roller can be placed in a heating furnace (such as an oven) or in a general manufacturing line (at room temperature). It is best to place it in a heating furnace equipped with an air supply mechanism. By combining drying with the heating roller and hot air drying, the rapid temperature change between the heating rollers can be suppressed, and the shrinkage in the width direction can be easily controlled. The temperature of hot air drying should be 30°C~100°C. In addition, the hot air drying time should be 1 second~300 seconds. The wind speed of the hot air should be around 10m/s~30m/s. In addition, the wind speed is the wind speed in the heating furnace, which can be measured with a mini fan-type digital anemometer.

B-1-6. Other treatments It is advisable to perform a cleaning treatment after the water stretching treatment and before the drying shrinkage treatment. The above cleaning treatment can be performed by immersing the PVA resin layer in a potassium iodide aqueous solution.

According to the above method, a laminate of thermoplastic resin substrate/polarizing film can be manufactured.

B-2. Dyeing of TAC film On the other hand, the TAC film is dyed with iodine. Dyeing can be performed in any appropriate manner. Dyeing can be performed, for example, by immersing a long strip of TAC film in a dyeing solution (typically an aqueous iodine solution) while conveying it on a roller. Dyeing is performed in such a way that the transmittance of the resulting dyed TAC film at a wavelength of 400nm becomes less than 65% and the Y-value transmittance becomes more than 80%. The transmittance and Y-value transmittance can be controlled by appropriately adjusting the iodine concentration of the aqueous iodine solution, the temperature of the aqueous iodine solution, and the dyeing time (immersion time). The iodine concentration of the aqueous iodine solution can be changed in accordance with the dyeing time (immersion time). The iodine concentration of the aqueous iodine solution is preferably 0.1% by weight or more, more preferably 0.5% by weight to 5.0% by weight, and more preferably 1.0% by weight to 3.0% by weight. If the iodine concentration is too low, the desired transmittance may not be obtained even if the dyeing process is carried out for a long time. The temperature of the iodine aqueous solution should be 20℃~30℃. The dyeing time can be changed according to the iodine concentration of the iodine aqueous solution. The dyeing time should be more than 30 seconds, preferably 50 seconds~400 seconds. If the dyeing time is too short, the desired transmittance may not be obtained. On the other hand, considering the manufacturing efficiency, it is not effective to extend the dyeing time unnecessarily.

B-3. Preparation of polarizing plate The dyed TAC film obtained in item B-2 is bonded to the polarizing film surface of the laminate of the thermoplastic resin substrate/polarizing film obtained in item B-1 through any appropriate adhesive. The adhesive may be, for example, a water-based adhesive or an active energy line curing adhesive. A laminate of thermoplastic resin substrate/polarizing film/dyed TAC film may be prepared in the above manner. The laminate may also be used directly as a polarizing plate. At this time, the thermoplastic resin substrate may function as an inner protective layer. Alternatively, the thermoplastic resin substrate may be peeled off from the laminate of the thermoplastic resin substrate/polarizing film/dyed TAC film, and the laminate of the dyed TAC film/polarizing film may be used as a polarizing plate. Alternatively, the thermoplastic resin substrate may be peeled off from the laminate of the thermoplastic resin substrate/polarizing film/dyed TAC film, and a resin film may be laminated to the peeled surface as an inner protective layer, and the laminate of the dyed TAC film/polarizing film/inner protective layer may be used as a polarizing plate.

C. Polarizing plate with phase difference layer C-1. Overall structure of polarizing plate with phase difference layer FIG2 is a schematic cross-sectional view of a polarizing plate with phase difference layer of an embodiment of the present invention. The polarizing plate with phase difference layer 100 of this embodiment has a polarizing plate 10 and a phase difference layer 20. The polarizing plate is the polarizing plate described in the above items A and B. The polarizing plate 10 of the illustrated example includes a polarizing film 11, a visual side protective layer 12, and an inner side protective layer 13. As described above, the inner side protective layer 13 may be omitted. In the polarizing plate with phase difference layer, the phase difference layer is typically arranged on the side of the polarizing plate opposite to the visual side.

As shown in FIG3 , in another embodiment of the polarizing plate 101 with a phase difference layer, another phase difference layer 50 and/or a conductive layer or an isotropic substrate 60 with a conductive layer may also be provided. The another phase difference layer 50 and the conductive layer or the isotropic substrate 60 with a conductive layer may be provided on the opposite side of the phase difference layer 20 to the polarizing plate 10 (the side opposite to the visual side). The refractive index characteristics of the another phase difference layer show the relationship of nz＞nx=ny. The another phase difference layer 50 and the conductive layer or the isotropic substrate 60 with a conductive layer are provided in sequence from the phase difference layer 20 side. The other phase difference layer 50 and the conductive layer or the isotropic substrate 60 with a conductive layer are arbitrary layers that can be provided as needed, and either or both of them can be omitted. In addition, for convenience, the phase difference layer 20 is sometimes referred to as the first phase difference layer, and the other phase difference layer 50 is sometimes referred to as the second phase difference layer. In addition, when a conductive layer or an isotropic substrate with a conductive layer can be provided, the polarizing plate with a phase difference layer can be applied to a so-called internal touch panel type input display device in which a touch sensor is incorporated between an image display unit (e.g., an organic EL unit) and a polarizing plate.

In the embodiment of the present invention, Re(550) of the first phase difference layer 20 is 100nm-190nm, and Re(450)/Re(550) is greater than 0.8 and less than 1. In addition, the angle formed by the slow axis of the first phase difference layer 20 and the absorption axis of the polarizing film 11 is 40°-50°.

The above embodiments can be combined appropriately, and changes that are obvious in the industry can be added to the components of the above embodiments. For example, the structure of the isotropic substrate 60 with a conductive layer provided on the outer side of the second phase difference layer 50 can be replaced with an optically equivalent structure (such as a laminate of the second phase difference layer and the conductive layer).

The polarizing plate with phase difference layer may further include other phase difference layers. The optical properties (such as refractive index properties, in-plane phase difference, Nz coefficient, photoelastic coefficient), thickness, and configuration position of other phase difference layers may be appropriately set according to the purpose.

The polarizing plate with a phase difference layer can be in the form of a single piece or in the form of a long strip. The so-called "long strip" in this specification means a long and narrow shape that is long enough relative to the width, for example, a long and narrow shape that is more than 10 times, and preferably more than 20 times, relative to the width. The long strip-shaped polarizing plate with a phase difference layer can be rolled into a roll. When the polarizing plate with a phase difference layer is in the form of a long strip, the polarizing plate and the phase difference layer are also in the form of a long strip. At this time, the polarizing film preferably has an absorption axis in the direction of the long strip. The first phase difference layer is preferably an obliquely stretched film having a slow axis in a direction forming an angle of 40°~50° relative to the direction of the long strip. If the polarizing film and the first phase difference layer are of the above-mentioned structure, a polarizing plate with a phase difference layer can be manufactured by roll-to-roll.

In actual use, an adhesive layer (not shown) can be provided on the side of the phase difference layer opposite to the polarizing plate, and the polarizing plate with the phase difference layer can be attached to the image display unit. In addition, it is preferable that a peeling film is temporarily attached to the surface of the adhesive layer before the polarizing plate with the phase difference layer is used. By temporarily attaching the peeling film, a roll can be formed while protecting the adhesive layer.

The total thickness of the polarizing plate with a phase difference layer is preferably less than 140µm, more preferably less than 120µm, more preferably less than 100µm, still more preferably less than 90µm, and still more preferably less than 85µm. The lower limit of the total thickness may be, for example, 80µm. According to the implementation form of the present invention, an extremely thin polarizing plate with a phase difference layer as described above can be realized. The polarizing plate with a phase difference layer may have extremely excellent flexibility and bending durability. The polarizing plate with a phase difference layer may be particularly suitable for use in a curved image display device and/or a flexible or bendable image display device. In addition, the so-called total thickness of the polarizing plate with a phase difference layer refers to the total thickness of all layers constituting the polarizing plate with a phase difference layer after deducting the adhesive layer used to make the polarizing plate with a phase difference layer adhere to an external adherend such as a panel or glass (that is, the total thickness of the polarizing plate with a phase difference layer does not include the thickness of the adhesive layer used to attach the polarizing plate with a phase difference layer to adjacent components such as an image display unit and the peeling film that can be temporarily adhered to its surface).

The first phase difference layer, the second phase difference layer, and the conductive layer or the isotropic substrate with the conductive layer are described in detail below. In addition, the first phase difference layer may also be an oriented solidified layer of a liquid crystal compound (hereinafter referred to as a liquid crystal oriented solidified layer). Regarding the liquid crystal oriented solidified layer, a modified example of the first phase difference layer is described in Item C-4.

C-2. First phase difference layer The first phase difference layer 20 may have any appropriate optical and/or mechanical properties according to the purpose. The first phase difference layer 20 typically has a slow axis. In one embodiment, the angle θ formed by the slow axis of the first phase difference layer 20 and the absorption axis of the polarizing film 11 is 40°~50° as described above, preferably 42°~48°, and more preferably about 45°. If the angle θ is within the above range, as described later, by making the first phase difference layer into a λ/4 plate, a polarizing plate with a phase difference layer having very excellent circular polarization characteristics (in terms of very excellent anti-reflection characteristics) can be obtained.

The refractive index characteristics of the first phase difference layer preferably show the relationship of nx＞ny≧nz. The first phase difference layer is typically provided to impart anti-reflection characteristics to the polarizing plate, and in one embodiment, can function as a λ/4 plate. At this time, the in-plane phase difference Re(550) of the first phase difference layer is 100nm~190nm as mentioned above, preferably 110nm~170nm, and more preferably 130nm~160nm. In addition, here "ny=nz" not only includes the case where ny and nz are completely the same, but also includes the case where they are substantially the same. Therefore, it is possible to have a situation where ny＜nz without compromising the effect of the present invention.

The Nz coefficient of the first phase difference layer is preferably 0.9 to 3, more preferably 0.9 to 2.5, more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3. By satisfying the above relationship, when the obtained polarizing plate with phase difference layer is used in an image display device, a very excellent reflection hue can be achieved.

The first phase difference layer can exhibit an inverse dispersion wavelength characteristic in which the phase difference value increases with the wavelength of the measured light, can exhibit a normal wavelength dispersion characteristic in which the phase difference value decreases with the wavelength of the measured light, and can also exhibit a flat wavelength dispersion characteristic in which the phase difference value hardly changes with the wavelength of the measured light. In one embodiment, the first phase difference layer exhibits an inverse dispersion wavelength characteristic. At this time, Re(450)/Re(550) of the phase difference layer is greater than 0.8 and less than 1 as described above, preferably greater than 0.8 and less than 0.95. If it is the above-mentioned structure, a very excellent anti-reflection property can be achieved.

The first phase difference layer includes a resin having an absolute value of a photoelastic coefficient of preferably 2×10 ^-11 m ² /N or less, more preferably 2.0×10 ^-13 m ² /N to 1.5×10 ^-11 m ² /N, and more preferably 1.0×10 ^-12 m ^{2 /N} to 1.2× ^{10 -11} m ² /N. When the absolute value of the photoelastic coefficient is within the above range, the phase difference is unlikely to change when shrinkage stress is generated during heating. As a result, thermal unevenness of the obtained image display device can be well prevented.

The first phase difference layer is typically formed of a stretched film of a resin film. The thickness of the first phase difference layer is preferably 70µm or less, preferably 45µm to 60µm. If the thickness of the first phase difference layer is within the above range, the curling during heating can be well suppressed and the curling during bonding can be well adjusted.

The first phase difference layer 20 can be formed of any appropriate resin film that can satisfy the above-mentioned characteristics. Representative examples of the resin include polycarbonate resins, polyester carbonate resins, polyester resins, polyvinyl acetal resins, polyarylate resins, cyclic olefin resins, cellulose resins, polyvinyl alcohol resins, polyamide resins, polyimide resins, polyether resins, polystyrene resins, and acrylic resins. These resins can be used alone or in combination (e.g., blended or copolymerized). When the first phase difference layer is formed of a resin film showing reverse dispersion wavelength characteristics, a polycarbonate resin or a polyester carbonate resin (hereinafter sometimes simply referred to as a polycarbonate resin) can be appropriately used.

As long as the effects of the present invention can be obtained, any appropriate polycarbonate resin can be used as the polycarbonate resin. For example, the polycarbonate resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic dimethanols, di-, tri- or polyethylene glycols, and alkylene glycols or spiroglycerol. The polycarbonate resin preferably includes structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, structural units derived from alicyclic dimethanols, and/or structural units derived from di, tri or polyethylene glycol; more preferably, it includes structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from di, tri or polyethylene glycol. The polycarbonate resin may also include structural units derived from other dihydroxy compounds as needed. In addition, the details of the polycarbonate resin that can be suitably used for the first phase difference layer and the method for forming the first phase difference layer are described in, for example, Japanese Patent Publication No. 2014-10291, Japanese Patent Publication No. 2014-26266, Japanese Patent Publication No. 2015-212816, Japanese Patent Table No. 2015-212817, and Japanese Patent Table No. 2015-212818, and the descriptions of these publications are cited in this specification as reference.

C-3. Second phase difference layer As described above, the second phase difference layer can be a so-called positive C-plate whose refractive index characteristics show the relationship of nz＞nx=ny. By using a positive C-plate as the second phase difference layer, oblique reflection can be well prevented, and the anti-reflection function can be widened to a wide viewing angle. At this time, the phase difference Rth(550) in the thickness direction of the second phase difference layer is preferably -50nm~-300nm, more preferably -70nm~-250nm, more preferably -90nm~-200nm, and particularly preferably -100nm~-180nm. Here, "nx=ny" includes not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. That is, the in-plane phase difference Re(550) of the second phase difference layer can be less than 10nm.

The second phase difference layer having the refractive index characteristic of nz＞nx=ny can be formed of any appropriate material. The second phase difference layer is preferably composed of a film containing a liquid crystal material fixed in a homeotropic alignment. The liquid crystal material (liquid crystal compound) that can achieve homeotropic alignment can be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the phase difference layer include the liquid crystal compound and the method for forming the phase difference layer described in paragraphs [0020] to [0028] of Japanese Patent Gazette No. 2002-333642. At this time, the thickness of the second phase difference layer is preferably 0.5µm~10µm, more preferably 0.5µm~8µm, and more preferably 0.5µm~5µm.

C-4. Variations of the first phase difference layer The first phase difference layer 20 may also have a laminated structure of a first liquid crystal orientation solidification layer and a second liquid crystal orientation solidification layer. In this case, either the first liquid crystal orientation solidification layer or the second liquid crystal orientation solidification layer may function as a λ/4 plate, and the other may function as a λ/2 plate. Therefore, the thickness of the first liquid crystal orientation solidification layer and the second liquid crystal orientation solidification layer may be adjusted to obtain the desired in-plane phase difference of the λ/4 plate or the λ/2 plate. For example, when the first liquid crystal orientation solidification layer functions as a λ/2 plate and the second liquid crystal orientation solidification layer functions as a λ/4 plate, the thickness of the first liquid crystal orientation solidification layer is, for example, 2.0µm to 3.0µm, and the thickness of the second liquid crystal orientation solidification layer is, for example, 1.0µm to 2.0µm. At this time, the in-plane phase difference Re(550) of the first liquid crystal orientation solidification layer is preferably 200nm~300nm, preferably 230nm~290nm, and more preferably 250nm~280nm. The in-plane phase difference Re(550) of the second liquid crystal orientation solidification layer is preferably 100nm~190nm, preferably 110nm~170nm, and more preferably 130nm~160nm. The angle formed by the slow axis of the first liquid crystal orientation solidification layer and the absorption axis of the polarizing film is preferably 10°~20°, preferably 12°~18°, and more preferably about 15°. The angle formed by the slow axis of the second liquid crystal orientation solidification layer and the absorption axis of the polarizing film is preferably 70°~80°, preferably 72°~78°, and more preferably about 75°. If the structure is as described above, characteristics close to the ideal reverse wavelength dispersion characteristics can be obtained, and as a result, very excellent anti-reflection characteristics can be achieved. The refractive index characteristics of the first liquid crystal orientation solidification layer and the second liquid crystal orientation solidification layer are representatively exhibiting the relationship of nx＞ny=nz. The Nz coefficient of the first liquid crystal orientation solidification layer and the second liquid crystal orientation solidification layer is preferably 0.9~1.5, and preferably 0.9~1.3. The liquid crystal compound constituting the first liquid crystal orientation solidification layer and the second liquid crystal orientation solidification layer, and the method for forming the first liquid crystal orientation solidification layer and the second liquid crystal orientation solidification layer are described in, for example, Japanese Patent Publication No. 2006-163343. The description of the publication is cited in this specification as a reference. In addition, when the first phase difference layer has the above-mentioned layered structure, the second phase difference layer can be omitted.

C-5. Conductive layer or isotropic substrate with conductive layer The conductive layer can be formed by forming a metal oxide film on any appropriate substrate using any appropriate film forming method (e.g. vacuum evaporation, sputtering, CVD, ion plating, spraying, etc.). Metal oxides include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. Among them, indium-tin composite oxide (ITO) is preferred.

When the conductive layer comprises a metal oxide, the thickness of the conductive layer is preferably 50 nm or less, more preferably 35 nm or less. The lower limit of the thickness of the conductive layer is preferably 10 nm.

The conductive layer can be transferred from the substrate to the first phase difference layer (or the second phase difference layer if there is a second phase difference layer) and the conductive layer can be used alone as a constituent layer of the polarizing plate with a phase difference layer, or can be laminated on the first phase difference layer (or the second phase difference layer if there is a second phase difference layer) in the form of a laminate of the conductive layer and the substrate (substrate with conductive layer). It is preferred that the substrate is optically isotropic, so the conductive layer can be used as an isotropic substrate with a conductive layer for the polarizing plate with a phase difference layer.

Any suitable isotropic substrate can be used as the optically isotropic substrate (isotropic substrate). The material constituting the isotropic substrate may include, for example, a material having a main skeleton of a resin without a conjugated system such as a norbornene resin or an olefin resin, and a material having a cyclic structure such as a lactone ring or a pentylimide ring in the main chain of an acrylic resin. If the above-mentioned material is used, the phase difference exhibited by the orientation of the molecular chain can be suppressed to a smaller value when forming the isotropic substrate. The thickness of the isotropic substrate is preferably less than 50µm, and more preferably less than 35µm. The lower limit of the thickness of the isotropic substrate is, for example, 20µm.

The conductive layer and/or the conductive layer of the isotropic substrate with the conductive layer can be patterned as needed. Conductive parts and insulating parts can be formed by patterning. As a result, electrodes can be formed. The electrodes can function as touch sensing electrodes for sensing contact with the touch panel. Any appropriate method can be used for patterning. Specific examples of patterning methods include wet etching and screen printing.

D. Image display device The polarizing plate described in the above items A and B or the polarizing plate with a phase difference layer described in the above item C can be applied to an image display device. Therefore, the embodiment of the present invention includes an image display device using the polarizing plate or the polarizing plate with a phase difference layer. Representative examples of image display devices include liquid crystal display devices and electroluminescent (EL) display devices (such as organic EL display devices and inorganic EL display devices). The image display device of the embodiment of the present invention has a polarizing plate or a polarizing plate with a phase difference layer on its viewing side. The polarizing plate with a phase difference layer is laminated in such a manner that the phase difference layer becomes the side of the image display unit (such as a liquid crystal unit, an organic EL unit, and an inorganic EL unit) (such a manner that the polarizing film becomes the viewing side). In one embodiment, the image display device has a curved shape (essentially a curved display screen), and/or is bendable or foldable. By using a polarizing plate or a polarizing plate with a phase difference layer as described above, the reflection hue of the image display device can be made close to neutral. Therefore, according to the embodiment of the present invention, a method for adjusting the image of the image display device can also be provided.

EXAMPLES The present invention is specifically described below with reference to examples, but the present invention is not limited to the examples. The methods for measuring the various properties are as described below. In addition, unless otherwise specified, the "parts" and "%" in the examples and comparative examples are based on weight. (1) The thickness below 10µm is measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"). The thickness greater than 10µm is measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C"). (2) Single body transmittance and polarization degree The polarizing plates used in the embodiments and comparative examples were measured using an ultraviolet-visible spectrophotometer (V-7100 manufactured by JASCO Corporation), and the measured single body transmittance Ts, parallel transmittance Tp, and orthogonal transmittance Tc were used as Ts, Tp, and Tc of the polarizing film, respectively. These Ts, Tp, and Tc were measured using the 2-degree field of view (C light source) of JIS Z8701 and the Y values obtained by performing visual sensitivity correction. In addition, the protective layer of the polarizing plates used in the embodiments and comparative examples has a hard coating (HC) layer on the surface, and the refractive index of the protective layer is 1.50, and the refractive index of the HC layer is 1.53. In addition, the refractive index of the surface of the polarizing film on the opposite side of the protective layer is 1.53. The polarization degree P is obtained from the obtained Tp and Tc using the following formula. Polarization degree P (%) = {(Tp-Tc)/(Tp+Tc)} ^{1 /2} × 100 In addition, the same measurement can be performed using a spectrophotometer such as LPF-200 manufactured by Otsuka Electronics Co., Ltd. In terms of transmittance, regardless of the transmittance of the protective layer or the transmittance of the polarizing plate, the value is the value when the surface refractive index is 1.50/1.53. When the combination of the surface refractive index of the measured structure is different from this, theoretical correction is performed according to the change in the surface refractive index and the change in the reflection from the air interface (surface reflection). For example, when measuring the structure of TAC/polarizing film with HC layer (set to transmittance 40%), the surface refractive index combination is 1.53/1.53. Therefore, by setting it to the measured value + 0.2%, it can be converted to the transmittance of the polarizing plate as 1.50/1.53. The transmittance of the TAC film unit with HC layer has a refractive index combination of 1.50/1.53, so no correction is performed. (3) Front reflection hue The polarizing plate with phase difference layer obtained in the embodiment and comparative example was attached to a reflective plate (manufactured by TORAY Film Co., Ltd., trade name "DMS-X42"; reflectivity 86%, reflection hue a ^* =-0.22, b ^* =0.32 without polarizing plate) using an acrylic adhesive without UV absorption function to prepare a measurement sample. At this time, the phase difference layer side of the polarizing plate with phase difference layer is bonded to the reflective plate in a manner opposite to each other. The sample is measured by a spectrophotometer (CM-2600d manufactured by Konica Minolta) using the SCE method, and the values of a ^* and b ^* are substituted into √(a ^*2 +b ^*2 ) to obtain the front reflection hue.

[Example 1-1] 1. Preparation of polarizing film The thermoplastic resin substrate is a long strip of amorphous isophthalic acid copolymer polyethylene terephthalate film (thickness: 100µm) with a water absorption rate of 0.75% and a Tg of about 75°C. One side of the resin substrate is subjected to a corona treatment. 13 parts by weight of potassium iodide is added to 100 parts by weight of a PVA-based resin prepared by mixing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetyl acetyl modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z410") in a ratio of 9:1, and then dissolved in water to prepare a PVA aqueous solution (coating liquid). The PVA aqueous solution was applied to the corona treated surface of the resin substrate and dried at 60°C to form a PVA resin layer with a thickness of 13µm, thereby producing a laminate. The obtained laminate was subjected to free-end uniaxial stretching to 2.4 times in the longitudinal direction (long side direction) between rollers of different circumferential speeds in an oven at 130°C (air-assisted stretching treatment). Then, the laminate was immersed in an insolubilizing bath (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilization treatment). Next, the film was immersed in a dyeing bath (an iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 relative to 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration so that the monomer transmittance (Ts) of the polarizing film finally obtained becomes the desired value (dyeing treatment). Next, the film was immersed in a crosslinking bath (an aqueous boric acid solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid relative to 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment). Then, the laminate was immersed in an aqueous solution (boric acid concentration 4.0 wt%, potassium iodide 5.0 wt%) at a temperature of 70°C, and uniaxially stretched in the longitudinal direction (long side direction) between rollers of different circumferential speeds to a total stretching ratio of 5.5 times (in-water stretching treatment). Thereafter, the laminate was immersed in a cleaning bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a temperature of 20°C (cleaning treatment). Thereafter, it was dried in an oven maintained at 90°C while contacting a SUS heating roller maintained at a surface temperature of 75°C for about 2 seconds (drying shrinkage treatment). The shrinkage rate of the laminate in the width direction after drying and shrinking is 5.2%. After the above process, a polarizing film with a thickness of 5µm is formed on the resin substrate.

2. Dyeing of TAC film An HC-TAC film with a HC layer of 7µm thickness and a refractive index of 1.53 formed on a long TAC film (manufactured by Konica Minolta, trade name "KC-2UA", thickness 25µm) was immersed in a dyeing bath (iodine aqueous solution with an iodine concentration of 1.0 wt%) at a temperature of 25°C. The immersion time was 60 seconds. The transmittance of the obtained dyed TAC film at a wavelength of 400nm was 59.8%, and the transmittance Y value was 90.1%.

3. Preparation of polarizing plate The dyed TAC film with HC layer obtained in 2. is bonded to the surface of the polarizing film obtained in 1. (the surface opposite to the resin substrate) through a UV-curable adhesive. Specifically, the curable adhesive is applied to a total thickness of 1.0µm and bonded using a roller. Then, UV light is irradiated from the TAC film side to cure the adhesive. Then, after cutting the two ends, the resin substrate is peeled off to obtain a long strip of polarizing plate (width: 1300mm) with a structure of protective layer (dyed TAC film)/adhesive layer/polarizing film. The single transmittance of the polarizing plate (actually a polarizing film) is 43.0%, and the polarization degree is 99.995%.

4. Preparation of phase difference film constituting phase difference layer 4-1. Polymerization of polyester carbonate resin Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and a reflux cooler controlled at 100°C. 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 spiroglycerol (SPG), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC) and 1.19×10 ^-2 parts by mass (6.78×10 ^-5 mol) of calcium acetate monohydrate as a catalyst were fed. After the reactor is depressurized and replaced with nitrogen, it is heated with a heat medium and stirring is started when the internal temperature reaches 100°C. 40 minutes after the start of the temperature rise, the internal temperature reaches 220°C, and the pressure is reduced while the temperature is controlled and maintained. After reaching 220°C, it takes 90 minutes to make it 13.3 kPa. The phenol vapor generated as a by-product of the polymerization reaction is introduced into a 100°C reflux cooler to return a small amount of monomer components contained in the phenol vapor to the reactor, and the uncondensed phenol vapor is introduced into a 45°C condenser for recovery. After nitrogen is introduced into the first reactor to temporarily return it to atmospheric pressure, the oligomerized reaction solution in the first reactor is transferred to the second reactor. Next, the temperature and pressure in the second reactor were raised and reduced, and the internal temperature reached 240°C and the pressure reached 0.2 kPa in 50 minutes. Then, polymerization was carried out until the predetermined stirring power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor to restore the pressure, and the generated polyester carbonate resin was extruded into water, and the bundle was cut to obtain pellets.

4-2. Preparation of phase difference film The obtained polyester carbonate resin (pellets) was vacuum dried at 80°C for 5 hours, and then a thin film forming device equipped with a uniaxial extruder (manufactured by Toshiba Machine Co., Ltd., cylinder setting temperature: 250°C), a T-die (width 200mm, setting temperature: 250°C), a cooling roller (setting temperature: 120~130°C) and a winder was used to prepare a long strip of resin film with a thickness of 135µm. The obtained long strip of resin film was stretched in the width direction at a stretching temperature of 133°C and a stretching ratio of 2.8 times to obtain a phase difference film with a thickness of 48µm. The Re(550) of the obtained phase difference film is 144nm, the Re(450)/Re(550) is 0.82, and the Nz coefficient is 1.12.

5. Preparation of polarizing plate with phase difference layer The phase difference film obtained in 4. is bonded to the surface of the polarizing film of the polarizing plate obtained in 3. through an acrylic adhesive (thickness 5µm). At this time, the absorption axis of the polarizing film and the slow axis of the phase difference film are bonded in a manner that forms an angle of 45°. According to the above method, a polarizing plate with a phase difference layer having a structure of a protective layer/bonding layer/polarizing film/adhesive layer/phase difference layer is obtained. The total thickness of the obtained polarizing plate with a phase difference layer is 84µm. The obtained polarizing plate with a phase difference layer is provided for the evaluation of (3) above. The results are listed in Table 1.

[Example 1-2] The TAC film was dyed in the same manner as in Example 1-1 except that the dyeing time was set to 120 seconds. The transmittance of the obtained dyed TAC film at a wavelength of 400nm was 52.8%, and the transmittance Y value was 89.2%. A polarizing plate with a phase difference layer was prepared in the same manner as in Example 1-1 except that the dyed TAC film was used. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1-1. The results are listed in Table 1.

[Example 1-3] The TAC film was dyed in the same manner as in Example 1-1 except that the dyeing time was set to 300 seconds. The transmittance of the obtained dyed TAC film at a wavelength of 400nm was 31.9%, and the transmittance Y value was 88.4%. A polarizing plate with a phase difference layer was prepared in the same manner as in Example 1-1 except that the dyed TAC film was used. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1-1. The results are listed in Table 1.

[Comparative Example 1] Except for using an undyed TAC film, a polarizing plate with a phase difference layer was prepared in the same manner as in Example 1-1. The transmittance of the undyed TAC film at a wavelength of 400nm was 68.5%, and the transmittance Y value was 92.1%. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1-1. The results are listed in Table 1.

[Example 2-1] The dyeing conditions were adjusted to produce a polarizing film with a single body transmittance of 44.0%. A polarizing plate with a phase difference layer was produced in the same manner as in Example 1-1 except that the polarizing film was used. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1-1. The results are listed in Table 1.

[Example 2-2] Except for using the polarizing film produced in Example 2-1, a polarizing plate with a phase difference layer was produced in the same manner as in Example 1-2. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1-1. The results are listed in Table 1.

[Example 2-3] Except for using the polarizing film produced in Example 2-1, a polarizing plate with a phase difference layer was produced in the same manner as in Example 1-3. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1-1. The results are listed in Table 1.

[Comparative Example 2] Except for using the polarizing film prepared in Example 2-1, a polarizing plate with a phase difference layer was prepared in the same manner as in Comparative Example 1. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1-1. The results are listed in Table 1.

[Table 1]

[Evaluation] As can be seen from Table 1, according to the embodiment of the present invention, by using a dyed TAC film as a protective layer, the reflection hue can be made closer to a neutral state than the comparative example.

Industrial Applicability The polarizing plate with phase difference layer of the present invention can be suitably used as a circular polarizing plate for liquid crystal display devices, organic EL display devices and inorganic EL display devices.

10: Polarizing plate 11: Polarizing film 12: Visual side protective layer 13: Inner side protective layer 20: Phase difference layer (first phase difference layer) 50: Another phase difference layer (second phase difference layer) 60: Conductive layer or isotropic substrate with conductive layer 100: Polarizing plate with phase difference layer 101: Polarizing plate with phase difference layer 200: Laminated body G1~G4: Guide rollers R1~R6: Transport rollers

FIG. 1 is a schematic diagram showing an example of a drying and shrinking treatment using a heating roller in a method for manufacturing a polarizing film used in a polarizing plate or a polarizing plate with a phase difference layer according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional diagram of a polarizing plate with a phase difference layer according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional diagram of a polarizing plate with a phase difference layer according to another embodiment of the present invention.

10: Polarizing plate

11: Polarizing film

12: Visual side protection layer

13: Inner protective layer

20: Phase difference layer (first phase difference layer)

100: Polarizing plate with phase difference layer

Claims (15)

A dyed cellulose triacetate film, which has been dyed with iodine and has a transmittance of less than 65% at a wavelength of 400nm and a transmittance Y of more than 80% after correction of visual sensitivity. A polarizing plate, comprising a polarizing film and a protective layer disposed on at least one side of the polarizing film; the thickness of the polarizing film is less than 8 μm; the protective layer is composed of a dyed triacetate cellulose film as described in claim 1. A method for manufacturing a polarizing plate is a method for manufacturing a polarizing plate as claimed in claim 2, comprising the following steps: forming a polyvinyl alcohol-based resin layer on one side of a long thermoplastic resin substrate to form a laminate; subjecting the laminate to dyeing and stretching treatments to form the polyvinyl alcohol-based resin layer into a polarizing film; dyeing a cellulose triacetate film with iodine to make its transmittance at a wavelength of 400nm less than 65% and to make its transmittance Y after visual sensitivity correction more than 80%; and laminating the dyed cellulose triacetate film to the polarizing film. The manufacturing method of the polarizing plate as claimed in claim 3, wherein the dyeing comprises immersing the cellulose triacetate film in an iodine aqueous solution having an iodine concentration of 0.1% by weight or more. A polarizing plate with a phase difference layer, comprising the polarizing plate as claimed in claim 2 and a phase difference layer disposed on the side of the polarizing plate opposite to the visual recognition side; the Re(550) of the phase difference layer is 100nm~190nm, and the Re(450)/Re(550) is greater than 0.8 and less than 1; the angle formed by the slow axis of the phase difference layer and the absorption axis of the polarizing film of the polarizing plate is 40°~50°. As in claim 5, the polarizing plate with a phase difference layer, wherein the phase difference layer is made of a polycarbonate resin film. As in claim 5 or 6, the polarizing plate with a phase difference layer has another phase difference layer outside the aforementioned phase difference layer, and the refractive index characteristics of the other phase difference layer show the relationship of nz>nx=ny. The polarizing plate with phase difference layer as in claim 5 or 6 is in the shape of a long strip; the polarizing film has an absorption axis in the direction of the long strip; the phase difference layer is an obliquely stretched film having a slow axis in a direction forming an angle of 40° to 50° relative to the direction of the long strip. The polarizing plate with a phase difference layer as in claim 8 can be rolled into a roll. A polarizing plate with a phase difference layer, comprising a polarizing plate as claimed in claim 2 and a phase difference layer disposed on the side of the polarizing plate opposite to the viewing side; the phase difference layer has a layered structure of an oriented solidified layer of a first liquid crystal compound and an oriented solidified layer of a second liquid crystal compound; the Re(550) of the oriented solidified layer of the first liquid crystal compound is 200nm~300nm, and the angle formed by its slow axis and the absorption axis of the aforementioned polarizing film is 10°~20°; the Re(550) of the oriented solidified layer of the second liquid crystal compound is 100nm~190nm, and the angle formed by its slow axis and the absorption axis of the polarizing film is 70°~80°. A polarizing plate with a phase difference layer as in any one of claim 5, 6, and 10, wherein the outer side of the phase difference layer further has a conductive layer or an isotropic substrate with a conductive layer. An image display device having a polarizing plate as in claim 2. An image display device having a polarizing plate with a phase difference layer as in any one of claims 5 to 11. The image display device of claim 12 or 13 is an organic electroluminescent display device or an inorganic electroluminescent display device. A method for adjusting an image of an image display device comprises the following steps: attaching a polarizing plate as in claim 2 or a polarizing plate with a phase difference layer as in any one of claims 5 to 11 to the visual side of an image display unit to make the reflected hue close to neutral.

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