TWI849323B - Polarizing plate with phase difference layer and image display device using the same - Google Patents

Abstract

The present invention provides a thin polarizing plate with a phase difference layer, which can inhibit the corrosion of metal components and the peeling of the phase difference layer and the adjacent layer when used in an image display device. The polarizing plate with a phase difference layer of the embodiment of the present invention has a polarizing plate including a polarizer, a phase difference layer and an adhesive layer in order from the viewing side. At least one iodine transmission inhibition layer is provided between the polarizer and the adhesive layer, and the iodine transmission inhibition layer is a cured product or a thermally cured product of a coating film of an organic solvent solution of a resin. The iodine transmission suppression layer adjacent to the phase difference layer comprises a resin and an isocyanate compound; the glass transition temperature of the resin is above 85°C and the weight average molecular weight Mw is above 25,000; the isocyanate compound is at least one selected from toluene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate and their derivatives; the content ratio of the resin to the isocyanate compound (resin/isocyanate compound) is 95/5~10/90.

Description

Polarizing plate with phase difference layer and image display device using the same

The present invention relates to a polarizing plate with a phase difference layer and an image display device using the same.

Background technology 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. In image display devices, polarizing plates and phase difference plates are generally used. In practice, although polarizing plates with phase difference layers that integrate polarizing plates and phase difference plates are widely used (such as patent document 1), recently, as the demand for thinning image display devices has increased, the demand for thinning polarizing plates with phase difference layers has also increased. In order to thin the polarizing plate with phase difference layer, the protective layer of the polarizer that has a great influence on the thickness is thinned (or the protective layer is omitted) and the phase difference film is thinned. However, if a thin polarizing plate with a phase difference layer is used in an image display device, the metal components of the image display device (such as electrodes, sensors, wiring, and metal layers) may corrode. Such corrosion of metal components is particularly evident in a high temperature and high humidity environment. Prior art literature Patent literature

Patent document 1: Japanese Patent No. 3325560

Summary of the invention Problems to be solved by the invention The present invention is completed to solve the above-mentioned previous problems. Its main purpose is to provide a thin polarizing plate with a phase difference layer, which can inhibit the corrosion of metal components and the peeling of the phase difference layer and the adjacent layer when used in an image display device. Means for solving the problem

The polarizing plate with phase difference layer of the present invention comprises, from the viewing side, a polarizing plate including a polarizer, a phase difference layer and an adhesive layer. Between the polarizer and the adhesive layer, at least one iodine transmission inhibition layer is provided, and the iodine transmission inhibition layer is a cured product or a thermally cured product of a coating film of an organic solvent solution of a resin. The iodine transmission suppression layer adjacent to the phase difference layer comprises a resin and an isocyanate compound; the glass transition temperature of the resin is above 85°C and the weight average molecular weight Mw is above 25,000; the isocyanate compound is at least one selected from toluene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate and their derivatives; the content ratio of the resin to the isocyanate compound (resin/isocyanate compound) is 95/5 to 10/90. In one embodiment, the iodine transmission suppression layer is provided with two or more layers. In one embodiment, the two or more iodine transmission suppression layers are all provided adjacent to the phase difference layer. In another embodiment, one of the two or more iodine transmission suppression layers is disposed adjacent to the polarizer. In one embodiment, the thickness of the iodine transmission suppression layer is 0.05 μm to 10 μm. In one embodiment, the resin constituting the iodine transmission suppression layer comprises an epoxy resin. In one embodiment, the resin constituting the iodine transmission suppression layer comprises a copolymer obtained by polymerizing a monomer mixture, wherein the monomer mixture comprises greater than 50 parts by weight of a (meth)acrylic monomer and greater than 0 parts by weight and less than 50 parts by weight of a monomer represented by formula (1): [Chemical Formula 1] (wherein, X represents a functional group, and the functional group includes at least one reactive group selected from the group consisting of vinyl, (meth)acryl, styryl, (meth)acrylamide, vinyl ether, epoxy, cyclobutyl, hydroxy, amino, aldehyde and carboxyl groups; ^R1 and ^R2 independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, an aryl group which may have a substituent or a heterocyclic group which may have a substituent; ^R1 and ^R2 may be linked to each other to form a ring). In one embodiment, the phase difference layer is an oriented solidified layer of a liquid crystal compound having a circular polarization function or an elliptical polarization function. In one embodiment, the phase difference layer is a single layer. The Re(550) of the phase difference layer is 100nm~190nm, and the angle formed by the slow axis of the phase difference layer and the absorption axis of the aforementioned polarizer is 40°~50°. In another embodiment, the phase difference layer has a laminated 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 polarizer 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 polarizer is 70°~80°. In one embodiment, the total thickness of the polarizing plate with a phase difference layer is less than 60 μm. According to another aspect of the present invention, an image display device is provided. The image display device has 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. Effect of the Invention

According to the embodiment of the present invention, by providing at least one specific iodine transmission suppression layer at a predetermined position of a thin polarizing plate with a phase difference layer, the corrosion of metal components can be suppressed when the polarizing plate with a phase difference layer is applied to an image display device. The iodine transmission suppression layer adjacent to the phase difference layer in the at least one iodine transmission suppression layer comprises a resin and an isocyanate compound; the glass transition temperature of the resin is above 85°C and the weight average molecular weight Mw is above 25000; the isocyanate compound is at least one selected from toluene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate and their derivatives; the content ratio of the resin to the isocyanate compound (resin/isocyanate compound) is 95/5 to 10/90. By placing such an iodine transmission suppression layer adjacent to the phase difference layer, in addition to the above-mentioned effects, the peeling of the phase difference layer and the adjacent layer (which is essentially the iodine transmission suppression layer) can be significantly suppressed.

Forms for implementing the invention 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 refractive index is the largest in the plane (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) is calculated by the formula: Re(λ)=(nx-ny)×d when the thickness of the layer (film) is set to d(nm). (3) Retardation in the thickness direction (Rth) "Rth(λ)" is the retardation in the thickness direction measured at 23°C with light of wavelength λnm. For example, "Rth(550)" is the retardation in the thickness direction measured at 23°C with light of wavelength 550nm. Rth(λ) is calculated by the formula: Rth(λ)=(nx-nz)×d when the thickness of the layer (film) is set to d(nm). (4) Nz coefficient The Nz coefficient is calculated by Nz=Rth/Re. (5) Angle When an angle is mentioned in this manual, the angle includes the angle in the clockwise direction and the counterclockwise direction relative to the reference direction. Therefore, for example, "45°" means ±45°.

A. Overall structure of polarizing plate with phase difference layer FIG. 1A is a schematic cross-sectional view of a polarizing plate with phase difference layer in one embodiment of the present invention. The polarizing plate with phase difference layer 100 shown in the figure has a polarizing plate 10, a phase difference layer 20 and an adhesive layer 30 in order from the viewing side. The polarizing plate 10 usually includes a polarizer 11 and a protective layer 12 disposed on the viewing side of the polarizer 11. Depending on the purpose, other protective layers (not shown) may also be provided on the side of the polarizer 11 opposite to the viewing side (protective layer 12). The phase difference layer 20 is usually an oriented solidified layer of a liquid crystal compound having a circular polarization function or an elliptical polarization function (hereinafter sometimes referred to as a liquid crystal oriented solidified layer). The adhesive layer 30 is provided as the outermost layer, and the polarizing plate with the phase difference layer can be attached to the image display device (essentially the image display unit).

In the embodiment of the present invention, at least one iodine transmission inhibition layer 40 is provided between the polarizer 11 and the adhesive layer 30. The iodine transmission inhibition layer is a solidified or thermosetting material of a coating film of an organic solvent solution of a resin. The resin typically has a glass transition temperature of 85°C or above and a weight average molecular weight Mw of 25,000 or above. By arranging such an iodine transmission inhibition layer at a specified position of a polarizing plate with a phase difference layer, when the polarizing plate with a phase difference layer is applied to an image display device, the iodine in the polarizer can be significantly inhibited from transferring to the image display device (essentially an image display unit). As a result, the corrosion of metal components (such as electrodes, sensors, wirings, and metal layers) of the image display device can be significantly suppressed (hereinafter, such effect is sometimes referred to as metal corrosion suppression effect). Such metal corrosion suppression effect is a unique effect of a thin polarizing plate with a phase difference layer (typically, a polarizing plate with a phase difference layer in which the phase difference layer is a liquid crystal oriented solidification layer). That is, the inventors of the present invention have discovered a new problem that when a thin polarizing plate with a phase difference layer is applied to an image display device, the metal components of the image display device may be corroded; because iodine exists in the corroded part, it can be explained that such metal component corrosion may be caused by iodine. Then, after repeated tests, it was found that the above-mentioned iodine penetration suppression layer (a cured layer or a heat-cured layer of a coating film of an organic solvent solution of a resin having a specific Tg and Mw) is a useful means for preventing iodine from migrating to an image display device (in fact, an image display unit). Furthermore, as described later, the iodine penetration suppression layer can be formed to be very thin, and by providing the iodine penetration suppression layer, the protective layer on the opposite side of the viewing side can be omitted. Therefore, due to the synergistic effect of these, it can also contribute to further thinning of the polarizing plate with a phase difference layer.

The iodine transmission suppression layer 40 may be provided in one layer or in two or more layers (for example, two layers, three layers, or four layers). In the embodiment shown in FIG. 1A , the iodine transmission suppression layer 40 is provided in one layer between the polarizer 11 and the phase difference layer 20 . The iodine transmission inhibition layer 40 may be provided in a single layer between the phase difference layer 20 and the adhesive layer 30, as in the case of the polarizing plate 101 with a phase difference layer shown in FIG1B ; or may be provided in a total of two layers between the polarizer 11 and the phase difference layer 20 and between the phase difference layer 20 and the adhesive layer 30, as in the case of the polarizing plate 102 with a phase difference layer shown in FIG1C ; or may be provided in a total of three layers, namely, two layers between the polarizer 11 and the phase difference layer 20 and one layer between the phase difference layer 20 and the adhesive layer 30, as in the case of the polarizing plate 103 with a phase difference layer shown in FIG1D . When the iodine transmission suppression layer is disposed between the polarizer and the phase difference layer (especially when the iodine transmission suppression layer is adjacent to the polarizer), it has the advantage of suppressing the transfer of iodine from the polarizer in a high temperature and high humidity environment, thereby improving reliability. When the iodine transmission suppression layer is disposed between the phase difference layer and the adhesive layer (especially when the iodine transmission suppression layer is adjacent to the adhesive layer), it has the advantage of preventing components other than iodine that are believed to affect metal corrosion (such as residual monomer components in ultraviolet curing adhesives and decomposition products of photoinitiators) from migrating into the adhesive, thereby achieving a higher metal corrosion suppression effect. By providing two or more layers of iodine transmission suppression layers, the metal corrosion suppression effect can be significantly improved. The more iodine is transmitted through the inhibition layer, the better the metal corrosion inhibition effect can be. The amount of iodine transmitted through the inhibition layer can be set in consideration of cost, manufacturing efficiency, the total thickness of the polarizing plate with phase difference layer, etc.

In the embodiment of the present invention, an iodine transmission suppression layer is arranged in a polarizing plate with a phase difference layer, and the iodine transmission suppression layer adjacent to the phase difference layer comprises a resin and an isocyanate compound; the glass transition temperature of the resin is above 85°C, and the weight average molecular weight Mw is above 25,000; the isocyanate compound is toluene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate and/or their derivatives (such as modified products, adducts); the content ratio of the resin to the isocyanate compound (resin/isocyanate compound) is 95/5~10/90. By making the iodine transmission suppression layer adjacent to the phase difference layer into such a structure, the excellent metal corrosion suppression effect mentioned above can be maintained and the peeling of the iodine transmission suppression layer and the phase difference layer can be significantly suppressed. That is, although as mentioned above, by providing the iodine transmission suppression layer which is a cured product or a heat-cured product of a coating film of an organic solvent solution of a specific resin, a very excellent metal corrosion suppression effect can be achieved, it is known that when such an iodine transmission suppression layer is adjacent to the phase difference layer (liquid crystal oriented solidified layer), the iodine transmission suppression layer and the phase difference layer (liquid crystal oriented solidified layer) may be peeled off in a high humidity environment. The inventors of the present invention have studied the peeling and found that the peeling can be significantly inhibited by adding a specific amount of a specific isocyanate compound to the resin constituting the iodine permeation inhibition layer, and finally completed the present invention. That is, such an effect can solve a previously unknown new problem, which is an unexpected excellent effect.

As described above, the phase difference layer 20 is a liquid crystal oriented solidification layer. The phase difference layer 20 may be a single layer as shown in FIG. 1A to FIG. 1D , or may be a laminated structure of a first liquid crystal oriented solidification layer 21 and a second liquid crystal oriented solidification layer 22 as shown in FIG. 2A to FIG. 2F . When the phase difference layer 20 has a laminated structure, the iodine penetration inhibition layer 40 may be provided in only one layer between the polarizer 11 and the first liquid crystal oriented solidification layer 21, as in the polarizing plate 104 with a phase difference layer as shown in FIG. 2A ; may also be provided in only one layer between the second liquid crystal oriented solidification layer 22 and the adhesive layer 30 (not shown); may also be provided in only one layer between the first liquid crystal oriented solidification layer 21 and the second liquid crystal oriented solidification layer 22 (not shown); Alternatively, as shown in FIG. 2B , a polarizing plate 105 with a phase difference layer may be provided with two layers between the polarizer 11 and the first liquid crystal orientation solidification layer 21 and between the second liquid crystal orientation solidification layer 22 and the adhesive layer 30; alternatively, as shown in FIG. 2C , a polarizing plate 106 with a phase difference layer may be provided with a total of two layers between the polarizer 11 and the first liquid crystal orientation solidification layer 21 and between the first liquid crystal orientation solidification layer 21 and the second liquid crystal orientation solidification layer 22. 2 layers; a total of 2 layers may be provided between the first liquid crystal orientation solidification layer 21 and the second liquid crystal orientation solidification layer 22 and between the second liquid crystal orientation solidification layer 22 and the adhesive layer 30, as in the case of the polarizing plate 107 with a phase difference layer as shown in FIG. 2D; a total of 2 layers may be provided between the polarizer 11 and the first liquid crystal orientation solidification layer 21 and between the first liquid crystal orientation solidification layer 21 and the second liquid crystal orientation solidification layer 30, as in the case of the polarizing plate 108 with a phase difference layer as shown in FIG. 2E. A total of three layers may be arranged between the polarizer 11 and the first liquid crystal oriented solidification layer 21, one layer may be arranged between the first liquid crystal oriented solidification layer 21 and the second liquid crystal oriented solidification layer 22, and one layer may be arranged between the second liquid crystal oriented solidification layer 22 and the adhesive layer 30, as in the polarizing plate 109 with a phase difference layer as shown in FIG. 2F. A total of four layers may be arranged between the polarizer 11 and the first liquid crystal oriented solidification layer 21, one layer may be arranged between the first liquid crystal oriented solidification layer 21 and the second liquid crystal oriented solidification layer 22, and one layer may be arranged between the second liquid crystal oriented solidification layer 22 and the adhesive layer 30.

1A to 1D and 2A to 2F are examples. The iodine transmission suppression layer 40 can be disposed in any appropriate number at any appropriate position between the polarizer 11 and the adhesive layer 30 for the purpose of viewing. For example, the above-mentioned embodiments can be appropriately combined, and the constituent elements in the above-mentioned embodiments can be modified as known in the industry. In addition, for example, more than five layers of iodine transmission suppression layers can be disposed.

In the polarizing plate with a phase difference layer, another phase difference layer and/or a conductive layer or an isotropic substrate with a conductive layer (neither of which is shown in the figure) may be further provided. Another phase difference layer is usually provided between the phase difference layer 20 and the adhesive layer 30 (i.e., outside the phase difference layer 20). The refractive index characteristic of another phase difference layer represents a relationship of nz＞nx=ny. The conductive layer or the isotropic substrate with a conductive layer is typically provided between the iodine transmission inhibition layer 40 and the adhesive layer 30 (i.e., outside the iodine transmission inhibition layer 40). Another phase difference layer and the conductive layer or the isotropic substrate with a conductive layer are typically provided in sequence from the phase difference layer 20 side. Another phase difference layer and the conductive layer or the isotropic substrate with the conductive layer are arbitrary layers provided as needed, and either or both of them may be omitted. When the conductive layer or the isotropic substrate with the conductive layer is provided, the polarizing plate with the phase difference layer can be applied to a so-called internal touch panel type input display device, in which a touch sensor is assembled between an image display unit (e.g., an organic EL unit) and the polarizing plate. In the embodiment of the present invention, by providing the conductive layer or the isotropic substrate with the conductive layer outside the iodine transmission suppression layer 40, the corrosion of the conductive layer can be significantly suppressed.

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, configuration position, etc. of other phase difference layers can be appropriately set according to the purpose.

In practice, a peeling film is preferably temporarily adhered to the surface of the adhesive layer 30 until the polarizing plate with a phase difference layer is used. By temporarily adhering the peeling film, the adhesive layer can be protected and the cylinder of the polarizing plate with a phase difference layer can be formed.

The total thickness of the polarizing plate with a phase difference layer is preferably less than 60 μm, more preferably less than 55 μm, more preferably less than 50 μm, and particularly preferably less than 40 μm. The lower limit of the total thickness may be, for example, 28 μm. According to the implementation form of the present invention, such an extremely thin polarizing plate with a phase difference layer can be realized, and even when such an extremely thin polarizing plate with a phase difference layer is applied to an image display device, the corrosion of the metal components (such as electrodes, sensors, wiring, and metal layers) of the image display device can be significantly suppressed. In addition, according to the implementation form of the present invention, in such an extremely thin polarizing plate with a phase difference layer, the peeling of the phase difference layer and the adjacent layer (essentially an iodine transmission inhibition layer) can be significantly suppressed. Moreover, such a polarizing plate with a phase difference layer can have extremely excellent flexibility and bending durability. Therefore, such a polarizing plate with a phase difference layer is particularly suitable for use in curved image display devices and/or bendable or foldable image display devices. Furthermore, the total thickness of the polarizing plate with a phase difference layer refers to the total thickness of the polarizing plate, the phase difference layer (when there is another phase difference layer, the phase difference layer and the other phase difference layer), the iodine transmission inhibition layer, and the bonding agent layer or adhesive layer used to laminate these (that is, the total thickness of the polarizing plate with a phase difference layer does not include the thickness of the conductive layer or the isotropic substrate with the conductive layer, the adhesive layer 30, and the peeling film that can be temporarily adhered to its surface).

The polarizing plate with phase difference layer can be in the form of a single sheet or a strip. In this specification, the term "strip" refers to a long and thin shape whose length is much longer than its width, for example, a long and thin shape whose length is more than 10 times, preferably more than 20 times, relative to its width. The strip-shaped polarizing plate with phase difference layer can be rolled into a cylindrical shape.

The following describes the constituent elements of the polarizing plate with phase difference layer in more detail. In addition, since the adhesive layer 30 can adopt a structure well known in the industry, the detailed description of the adhesive layer is omitted.

B. Polarizing plate B-1. Polarizer The polarizer is typically made of a polyvinyl alcohol (PVA) resin film containing a dichroic substance. The thickness of the polarizer is preferably 1μm~8μm, preferably 1μm~7μm, and more preferably 2μm~5μm. If the thickness of the polarizer is within this range, it can greatly help to thin the polarizing plate with a phase difference layer. Furthermore, in a thin polarizing plate with a phase difference layer using such a polarizer, the effect of the present invention is very significant.

The boric acid content of the polarizer is preferably 10% by weight or more, preferably 13% by weight to 25% by weight. If the boric acid content of the polarizer is within this range, the synergistic effect with the iodine content described later can well maintain the ease of warp adjustment during lamination, well suppress warp during heating, and improve the appearance durability during heating. The boric acid content can be calculated, for example, by the neutralization method using the following formula, based on the amount of boric acid contained per unit weight of the polarizer. [Mathematical formula 1] (g/mol)

The iodine content of the polarizer is preferably 2% by weight or more, preferably 2% by weight to 10% by weight. If the iodine content of the polarizer is within such a range, the synergistic effect with the boric acid content mentioned above can well maintain the ease of warp adjustment during lamination, well suppress the warp during heating, and improve the appearance durability during heating. The so-called "iodine content" in this specification refers to the amount of all iodine contained in the polarizer (PVA-based resin film). More specifically, when iodine in the polarizer exists in the form of iodine ions ( ^I- ), iodine molecules ( _I2 ), polyiodine ions ( _I3- ^, _I5- ⁾ , etc., the iodine content in this specification refers to the amount of iodine contained in all these forms. The iodine content can be calculated, for example, by the calibration curve method of fluorescent X-ray analysis. Furthermore, polyiodine ions exist in the polarizer in the form of a PVA-iodine complex. By forming such a complex, absorption dichroism can be expressed in the wavelength range of visible light. Specifically, the complex of PVA and triiodide ion (PVA･I ₃ ^- ) has an absorption peak near 470nm, and the complex of PVA and pentaiodide ion (PVA･I ₅ ^- ) has an absorption peak near 600nm. As a result, polyiodine ions can absorb light in a wide range of visible light depending on their form. On the other hand, iodine ion (I ^- ) has an absorption peak near 230nm, which is substantially unrelated to the absorption of visible light. Therefore, polyiodine ions existing in the form of a complex with PVA may be mainly related to the absorption performance of the polarizer.

The polarizer should preferably show absorption dichroism at any wavelength between 380nm and 780nm. The single transmittance Ts of the polarizer should preferably be 40% to 48%, preferably 41% to 46%. The polarization degree P of the polarizer should preferably be above 97.0%, preferably above 99.0%, and more preferably above 99.9%. The above single transmittance is usually measured using an ultraviolet-visible spectrometer, which is the Y value after correction for visual sensitivity. The above polarization degree is usually calculated based on the parallel transmittance Tp and the perpendicular transmittance Tc measured using an ultraviolet-visible spectrometer and corrected for visual sensitivity, using the following formula. Polarization degree (%) = {(Tp-Tc)/(Tp+Tc)} ^1/2 ×100

Polarizers can generally be manufactured using a laminate of two or more layers. A specific example of a polarizer obtained using a laminate is a polarizer obtained using a resin substrate and a laminate of a PVA-based resin layer formed by coating the resin substrate. A polarizer obtained by using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by the following method: a PVA-based resin solution is coated on the resin substrate, dried, and a PVA-based resin layer is formed on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; the laminate is stretched and dyed, and the PVA-based resin layer is used as a polarizer. Stretching generally includes immersing the laminate in a boric acid aqueous solution and then stretching it. Furthermore, stretching may further include stretching the laminate in the air at a high temperature (e.g., above 95° C.) before stretching in a boric acid aqueous solution, if necessary. The obtained resin substrate/polarizer laminate can be used directly (that is, the resin substrate can be used as a protective layer of the polarizer), or the resin substrate can be peeled off from the resin substrate/polarizer laminate and used after any appropriate protective layer is applied to the peeled off area layer according to the purpose. The detailed manufacturing method of such a polarizer is described in, for example, Japanese Patent Publication No. 2012-73580 and Patent No. 6470455. All the contents of these publications are cited in this specification as reference.

The manufacturing method of the polarizer typically includes the following steps: forming a polyvinyl alcohol resin layer including a halogenated compound 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 shrinking treatment on the laminate, wherein the drying shrinking treatment is performed by conveying the laminate in the length direction while heating the laminate so that the laminate shrinks by more than 2% in the width direction. Thus, a very thin polarizer with excellent optical properties and suppressed optical property unevenness can be provided. That is, by introducing auxiliary stretching, even when PVA is coated on the thermoplastic resin, the crystallinity of PVA can be improved, 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 achieve high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the orientation disorder and orientation reduction of the polyvinyl alcohol molecules can be suppressed compared to the case where the PVA-based resin layer does not contain a halogen. In this way, the optical properties of the polarizer obtained by the treatment steps of immersing the laminate in a liquid such as dyeing treatment and underwater stretching treatment can be improved. Furthermore, by shrinking the laminate in the width direction through a dry shrinking treatment, the optical properties can be improved.

B-2. Protective layer The protective layer 12 can be formed of any suitable film that can be used as a protective layer for a polarizer. Specific examples of the material that is the main component of the film include: cellulose resins such as triacetate cellulose (TAC), or polyester resins, polyvinyl alcohol resins, polycarbonate resins, polyamide resins, polyimide resins, polyether sulfone resins, polysulfone resins, polystyrene resins, polynorbornene resins, polyolefin resins, (meth)acrylic resins, acetate resins, and other transparent resins. In addition, thermosetting resins or ultraviolet curing resins such as (meth)acrylic resins, urethane resins, (meth)acrylic urethane resins, epoxy resins, and polysilicone resins can also be listed. In addition, for example, glassy polymers such as siloxane polymers can also be cited. In addition, the polymer film described in Japanese Patent Publication No. 2001-343529 (WO01/37007) can also be used. Regarding 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, a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used, and an example of a resin composition having an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be used. The polymer film can be, for example, an extruded product of the above resin composition.

As described below, the polarizing plate with a phase difference layer is usually arranged on the viewing side of the image display device, and the protective layer 12 is usually arranged on the viewing side. Therefore, the protective layer 12 may be subjected to surface treatments such as hard coating, anti-reflection, anti-sticking, and anti-glare treatments as needed. Furthermore/or, the protective layer 12 may be subjected to treatments to improve visibility when viewed through polarized sunglasses as needed (representatively, providing (elliptical) circular polarization function and providing ultra-high phase difference). By implementing such treatments, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the polarizing plate with a phase difference layer may also be suitable for use in image display devices that can be used outdoors.

The thickness of the protective layer is preferably 10 μm to 50 μm, more preferably 10 μm to 30 μm. Furthermore, when the surface treatment is performed, the thickness of the outer protective layer is the thickness including the thickness of the surface treatment layer.

C. Phase difference layer As described above, the phase difference layer 20 is usually a liquid crystal oriented solidified layer. By using a liquid crystal compound, the difference between nx and ny of the obtained phase difference layer can be made very large compared to non-liquid crystal materials, so the thickness of the phase difference layer that can be used to obtain the desired in-plane phase difference can be very small. As a result, the polarizing plate with a phase difference layer can be further thinned. The so-called "liquid crystal oriented solidified layer" in this specification refers to a layer in which the liquid crystal compound is oriented in a predetermined direction within the layer and its oriented state is fixed. Furthermore, as described below, the "oriented solidified layer" includes the concept of an oriented solidified layer obtained by curing a liquid crystal monomer. In this embodiment, the representative one is that the rod-shaped liquid crystal compound is oriented in the slow axis direction of the phase difference layer (oriented along the plane).

Examples of liquid crystal compounds include liquid crystal compounds whose liquid crystal phase is a nematic phase (nematic liquid crystal). For example, such liquid crystal compounds may be liquid crystal polymers or liquid crystal monomers. The liquid crystal compound may have a lyotropic or thermotropic mechanism of expression of liquid crystal properties. Liquid crystal polymers and liquid crystal monomers may be used alone or in combination.

When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer and a cross-linking monomer. The reason is that by polymerizing or cross-linking (i.e., hardening) the liquid crystal monomer, the orientation state of the liquid crystal monomer can be fixed. After the liquid crystal monomer is oriented, for example, if the liquid crystal monomers are polymerized or cross-linked with each other, the above-mentioned orientation state can be fixed. Here, a polymer is formed by polymerization, and a three-dimensional mesh structure is formed by cross-linking, but these are non-liquid crystal. Therefore, the formed phase difference layer, for example, will not undergo a transition to a liquid crystal phase, a glass phase, or a crystalline phase due to temperature changes that are unique to liquid crystal compounds. As a result, the phase difference layer becomes a phase difference layer with extremely excellent stability that is not affected by temperature changes.

The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on its type. Specifically, the temperature range is preferably 40°C to 120°C, more preferably 50°C to 100°C, and more preferably 60°C to 90°C.

Any suitable liquid crystal monomer may be used for the above-mentioned liquid crystal monomer. For example, polymerizable liquid crystal original compounds described in Japanese Patent Publication No. 2002-533742 (WO00/37585), EP358208 (US5211877), EP66137 (US4388453), WO93/22397, EP0261712, DE19504224, DE4408171 and GB2280445 may be used. Specific examples of such polymerizable liquid crystal original compounds include: BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Sillicon-CC3767. For the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferred.

The liquid crystal orientation solidified layer can be formed by performing an orientation treatment on the surface of a predetermined substrate, applying a coating liquid containing a liquid crystal compound on the surface, orienting the liquid crystal compound in a direction corresponding to the orientation treatment, and fixing the orientation state. In one embodiment, the substrate is any appropriate resin film, and the liquid crystal orientation solidified layer formed on the substrate can be transferred to the surface of an adjacent layer (e.g., a polarizer, an iodine transmission inhibition layer).

Any appropriate orientation treatment may be used for the above-mentioned orientation treatment. Specifically, mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment may be mentioned. Specific examples of mechanical orientation treatment include friction treatment and stretching treatment. Specific examples of physical orientation treatment include magnetic field orientation treatment and electric field orientation treatment. Specific examples of chemical orientation treatment include oblique evaporation and optical orientation treatment. Any appropriate treatment conditions may be used for each orientation treatment according to the purpose.

The alignment of the liquid crystal compound is carried out by treating it at a temperature that exhibits a liquid crystal phase according to the type of the liquid crystal compound. By performing such a temperature treatment, the liquid crystal compound becomes a liquid crystal state, and the liquid crystal compound is aligned according to the alignment treatment direction of the substrate surface.

In one embodiment, the alignment state is fixed by cooling the aligned liquid crystal compound. When the liquid crystal compound is a polymerizable monomer or a crosslinking monomer, the alignment state is fixed by subjecting the aligned liquid crystal compound to a polymerization treatment or a crosslinking treatment.

Specific examples of liquid crystal compounds and details of the method for forming the oriented solidified layer are described in Japanese Patent Application Laid-Open No. 2006-163343, which is incorporated herein by reference.

In one embodiment, the phase difference layer 20 is a single layer as shown in FIG. 1A to FIG. 1D. When the phase difference layer 20 is composed of a single layer, its thickness is preferably 0.5 μm to 7 μm, and more preferably 1 μm to 5 μm. By using a liquid crystal compound, a much thinner thickness than a resin film can be achieved to achieve the same in-plane phase difference as a resin film.

As mentioned above, the phase difference layer usually has a circular polarization function or an elliptical polarization function. The refractive index characteristics of the phase difference layer usually show the relationship of nx＞ny=nz. The phase difference layer is usually provided to impart anti-reflection characteristics to the polarizing plate, and when the phase difference layer is a single layer, it can act as a λ/4 plate. At this time, the in-plane phase difference Re(550) of the phase difference layer is preferably 100nm~190nm, preferably 110nm~170nm, and more preferably 130nm~160nm. Furthermore, here "ny=nz" not only includes the situation where ny and nz are completely equal, but also includes the situation where they are substantially equal. Therefore, within the scope without damaging the effect of the present invention, there may be a situation where ny＞nz or ny＜nz.

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

The phase difference layer can show an inverse dispersion wavelength characteristic in which the phase difference value increases with the wavelength of the measured light, can show a positive wavelength dispersion characteristic in which the phase difference value decreases with the wavelength of the measured light, or can show a flat wavelength dispersion characteristic in which the phase difference value is almost constant regardless of the wavelength of the measured light. In one embodiment, the phase difference layer shows an inverse dispersion wavelength characteristic. In this case, Re(450)/Re(550) of the phase difference layer is preferably greater than 0.8 and less than 1, and preferably greater than 0.8 and less than 0.95. If it is configured in this way, a very excellent anti-reflection characteristic can be achieved.

The angle θ formed by the slow axis of the phase difference layer 20 and the absorption axis of the polarizer 11 is preferably 40° to 50°, preferably 42° to 48°, and more preferably about 45°. If the angle θ is within such a range, by making the phase difference layer a λ/4 plate as described above, 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.

In another embodiment, the phase difference layer 20 may have a laminated structure of a first liquid crystal orientation solidification layer 21 and a second liquid crystal orientation solidification layer 22 as shown in FIG. 2A to FIG. 2F. In this case, either the first liquid crystal orientation solidification layer 21 or the second liquid crystal orientation solidification layer 22 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 21 and the second liquid crystal orientation solidification layer 22 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 21 acts as a λ/2 plate and the second liquid crystal orientation solidification layer 22 acts as a λ/4 plate, the thickness of the first liquid crystal orientation solidification layer 21 is, for example, 2.0 μm to 3.0 μm, and the thickness of the second liquid crystal orientation solidification layer 22 is, for example, 1.0 μm to 2.0 μm. At this time, the in-plane phase difference Re(550) of the first liquid crystal orientation solidification layer is preferably 200 nm to 300 nm, preferably 230 nm to 290 nm, and more preferably 250 nm to 280 nm. The in-plane phase difference Re(550) of the second liquid crystal orientation solidification layer is the same as described above for a single layer. The angle formed by the slow axis of the first liquid crystal orientation solidification layer and the absorption axis of the polarizer is preferably 10° to 20°, preferably 12° to 18°, and more preferably about 15°. The angle formed by the slow axis of the second liquid crystal oriented solidification layer and the absorption axis of the polarizer is preferably 70°~80°, preferably 72°~78°, and more preferably about 75°. If so constituted, a characteristic close to the ideal reverse wavelength dispersion characteristic can be obtained, and as a result, a very excellent anti-reflection characteristic can be achieved. The liquid crystal compound constituting the first liquid crystal oriented solidification layer and the second liquid crystal oriented solidification layer, the formation method of the first liquid crystal oriented solidification layer and the second liquid crystal oriented solidification layer, the optical characteristics, etc. are the same as the above description of the single layer.

D. Iodine penetration inhibition layer As described above, the iodine penetration inhibition layer is a cured or thermosetting material of a coating film of an organic solvent solution of a resin. If it is constructed in this way, the thickness can be made very thin (for example, less than 10μm). The thickness of the iodine penetration inhibition layer is preferably 0.05μm~10μm, preferably 0.08μm~5μm, more preferably 0.1μm~1μm, and particularly preferably 0.2μm~0.7μm. Furthermore, if it is constructed in this way, the iodine penetration inhibition layer can be formed directly (that is, without passing through a binder layer or an adhesive layer) on an adjacent layer (for example, a polarizer, a phase difference layer). According to the embodiment of the present invention, as described above, the polarizer, the phase difference layer and the iodine transmission suppression layer are very thin, and the adhesive layer or the adhesive layer for laminating the iodine transmission suppression layer can be omitted, so the total thickness of the polarizing plate with the phase difference layer can be made extremely thin. Furthermore, such an iodine transmission suppression layer has the advantage of excellent moisture durability because it has lower moisture absorption and moisture permeability than the solidified product of the aqueous coating film such as the aqueous solution or the aqueous dispersion. As a result, the optical characteristics can be maintained even in a high temperature and high humidity environment, and a polarizing plate with a phase difference layer with excellent durability can be realized. Moreover, such an iodine penetration inhibition layer can suppress the adverse effects on the polarizing plate (polarizer) under irradiation, for example, compared with the cured product of the ultraviolet curable resin. The iodine penetration inhibition layer is preferably a cured product of the coating film of the organic solvent solution of the resin. Compared with the cured product, the cured product shrinks less during film formation and does not contain residual monomers, etc., so it can suppress the degradation of the film body and suppress the adverse effects on the polarizing plate (polarizer) caused by residual monomers, etc.

Furthermore, the glass transition temperature (Tg) of the resin constituting the iodine penetration inhibition layer is above 85°C, and the weight average molecular weight Mw is above 25,000. If the Tg and Mw of the resin are within such a range, the synergistic effect with the effect produced by the iodine penetration inhibition layer formed by a cured or thermosetting material of a coating film of an organic solvent solution of the resin can still significantly inhibit the iodine in the polarizer from passing toward the image display unit, despite being very thin. As a result, when the polarizing plate with a phase difference layer is applied to an image display device, the corrosion of metal components can be significantly inhibited. The Tg of the resin is preferably above 90°C, more preferably above 100°C, more preferably above 110°C, and particularly preferably above 120°C. The upper limit of Tg can be, for example, 200°C. The Mw of the resin is preferably 30,000 or more, more preferably 35,000 or more, and more preferably 40,000 or more. The upper limit of Mw may be, for example, 150,000.

Furthermore, as described above, the iodine transmission suppression layer disposed in the polarizing plate with a phase difference layer, and the iodine transmission suppression layer adjacent to the phase difference layer, in addition to the above-mentioned resin, further contains an isocyanate compound. As for the isocyanate compound, toluene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate, and their derivatives (such as modified products, adducts) can be listed. The isocyanate compound can be used alone or in combination. The content ratio of the resin and the isocyanate compound (resin/isocyanate compound) is 95/5 to 10/90 as described above. The content ratio (resin/isocyanate compound) may be, for example, 95/5 to 50/50, for example, 90/10 to 60/40, for example, 85/15 to 70/30, and for example, 85/15 to 75/25. The content ratio (resin/isocyanate compound) may also be, for example, 40/60 to 5/95, for example, 30/70 to 5/95, and for example, 20/80 to 10/90. With such a configuration, as described above, the excellent metal corrosion inhibition effect can be maintained and the peeling of the iodine transmission inhibition layer and the phase difference layer can be significantly inhibited.

As for the resin constituting the iodine permeation inhibition layer, any appropriate thermoplastic resin or thermosetting resin can be used as long as it can form a cured product or a thermosetting product of a coating film of an organic solvent solution and has the above-mentioned Tg and Mw range. Thermoplastic resins are preferred. As for thermoplastic resins, for example, epoxy resins and acrylic resins can be listed. Epoxy resins and acrylic resins can also be used in combination. The following describes representative examples of epoxy resins and acrylic resins that can be used for the iodine permeation inhibition layer.

<Epoxy resin> As for epoxy resin, an epoxy resin having an aromatic epoxy group is preferably used. By using an epoxy resin having an aromatic epoxy group as the epoxy resin, when the iodine transmission suppression layer is disposed adjacent to the polarizer, the adhesion with the polarizer can be improved. Furthermore, when the adhesive layer is disposed adjacent to the iodine transmission suppression layer, the anchoring force of the adhesive layer can be improved. Regarding the epoxy resin having an aromatic ring, for example, there can be listed: bisphenol-type epoxy resins such as bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, and bisphenol S-type epoxy resin; phenol-formaldehyde-type epoxy resins such as phenol novolac epoxy resin, cresol novolac epoxy resin, and hydroxybenzaldehyde phenol novolac epoxy resin; polyfunctional epoxy resins such as tetrahydroxybenzyl methane epoxypropyl ether, tetrahydroxybenzophenone epoxypropyl ether, and epoxidized polyethylene phenol, naphthol-type epoxy resins, naphthalene-type epoxy resins, and biphenyl-type epoxy resins. It is preferred to use bisphenol A type epoxy resin, biphenyl type epoxy resin, and bisphenol F type epoxy resin. Only one type of epoxy resin may be used, or two or more types may be used in combination.

<Acrylic resin> Acrylic resins usually contain repeating units derived from (meth)acrylate monomers having a linear or branched structure as the main component. In this specification, "(meth)acrylic acid" refers to acrylic acid and/or methacrylic acid. Acrylic resins may contain repeating units derived from any appropriate copolymer monomers according to the purpose. Regarding copolymer monomers (comonomers), for example, carboxyl-containing monomers, hydroxyl-containing monomers, amide-containing monomers, aromatic ring-containing (meth)acrylates, and heterocyclic vinyl monomers can be listed. By appropriately setting the type, amount, combination, and copolymerization ratio of the monomer units, an acrylic resin having the above-specified Tg and Mw can be obtained.

<Boron-containing acrylic resin> In one embodiment, the acrylic resin includes a copolymer obtained by polymerizing a monomer mixture (hereinafter, sometimes referred to as a boron-containing acrylic resin), wherein the monomer mixture includes greater than 50 parts by weight of a (meth)acrylic monomer and greater than 0 parts by weight and less than 50 parts by weight of a monomer represented by formula (1) (hereinafter, sometimes referred to as a copolymer monomer): [Chemical Formula 2] (wherein, X represents a functional group, and the functional group includes at least one reactive group selected from the group consisting of vinyl, (meth)acryl, styryl, (meth)acrylamide, vinyl ether, epoxy, cyclohexane, hydroxy, amino, aldehyde and carboxyl groups; ^R1 and ^R2 independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent; ^R1 and ^R2 may be linked to each other to form a ring).

The boron-containing acrylic resin is represented by a repeating unit represented by the following formula. By polymerizing a monomer mixture comprising a copolymer monomer represented by formula (1) and a (meth) acrylic monomer, the boron-containing acrylic resin will have a substituent containing boron in the side chain (e.g., a repeating unit of k in the following formula). Thereby, when iodine is arranged adjacent to the polarizer through the inhibition layer, the adhesion with the polarizer can be improved. The substituent containing boron can be contained in the boron-containing acrylic resin continuously (i.e., in a block form) or randomly. [Chemical Formula 3] (wherein, R ⁶ represents an arbitrary functional group, j and k represent integers greater than 1).

<(Meth)acrylic acid monomer> Any appropriate (meth)acrylic acid monomer can be used as the (meth)acrylic acid monomer. For example, (meth)acrylic acid ester monomers having a linear or branched chain structure and (meth)acrylic acid ester monomers having a ring structure can be cited.

Examples of (meth)acrylate monomers having a linear or branched structure include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate. Methyl (meth)acrylate is preferably used. The (meth)acrylate monomer may be used alone or in combination of two or more.

Examples of the (meth)acrylate monomer having a ring structure include cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentyl (meth)acrylate, biphenyl (meth)acrylate, o-biphenyloxyethyl (meth)acrylate, o-biphenyloxyethoxyethyl (meth)acrylate, m-biphenyloxyethyl acrylate, p-biphenyloxyethyl (meth)acrylate, and 1-diphenyloxyethyl (meth)acrylate. The present invention can be used as a prepolymer of biphenyl monomers such as acrylate, o-biphenyloxy-2-hydroxypropyl (meth)acrylate, p-biphenyloxy-2-hydroxypropyl (meth)acrylate, m-biphenyloxy-2-hydroxypropyl (meth)acrylate, N-(meth)acryloyloxyethyl-o-biphenyl = carbamate, N-(meth)acryloyloxyethyl-p-biphenyl = carbamate, N-(meth)acryloyloxyethyl-m-biphenyl = carbamate, o-phenylphenol epoxypropyl ether acrylate, triphenyl (meth)acrylate, o-triphenyloxyethyl (meth)acrylate, etc. Preferably, 1-adamantyl (meth)acrylate and dicyclopentane (meth)acrylate are used. By using such monomers, a polymer having a higher glass transition temperature can be obtained. These monomers may be used alone or in combination of two or more.

Furthermore, a silsesquioxane compound having a (meth)acryl group may be used in place of the above-mentioned (meth)acrylate monomer. By using a silsesquioxane compound, an acrylic polymer having a higher glass transition temperature can be obtained. Silsesquioxane compounds are known to have various skeleton structures, such as cage structures, ladder structures, random structures, and the like. Silsesquioxane compounds may have only one of the above structures, or may have two or more of the above structures. Silsesquioxane compounds may be used alone, or two or more of them may be used in combination.

As for the silsesquioxane compound having a (meth)acryl group, for example, the MAC grade and AC grade of the SQ series of Toagosei Co., Ltd. can be used. The MAC grade is a silsesquioxane compound containing a methacryl group, and specific examples thereof include MAC-SQ TM-100, MAC-SQ SI-20, and MAC-SQ HDM. The AC grade is a silsesquioxane compound containing an acryl group, and specific examples thereof include AC-SQ TA-100 and AC-SQ SI-20.

The (meth)acrylic monomer is used in an amount greater than 50 parts by weight relative to 100 parts by weight of the monomer mixture.

<Comonomer> The copolymer monomer is a monomer represented by the above formula (1). By using such a copolymer monomer, a substituent containing boron is introduced into the side chain of the obtained polymer. The copolymer monomer may be used alone or in combination of two or more.

The aliphatic alkyl group in the above formula (1) includes a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, a cyclic alkyl group having 3 to 20 carbon atoms which may have a substituent, and an alkenyl group having 2 to 20 carbon atoms. The above aryl group includes a phenyl group having 6 to 20 carbon atoms which may have a substituent, a naphthyl group having 10 to 20 carbon atoms which may have a substituent, and the like. The heterocyclic group includes a 5-membered cyclic group or a 6-membered cyclic group containing at least one heteroatom which may have a substituent. Furthermore, ^R1 and ^R2 may be linked to each other to form a ring. ^R1 and ^R2 are preferably hydrogen atoms or linear or branched alkyl groups having 1 to 3 carbon atoms, and are preferably hydrogen atoms.

The reactive group included in the functional group represented by X is at least one selected from the group consisting of vinyl, (meth)acryl, styryl, (meth)acrylamide, vinyl ether, epoxy, cyclobutylene, hydroxy, amine, aldehyde and carboxyl. Preferred reactive groups are (meth)acryl and/or (meth)acrylamide. By having such reactive groups, when iodine is disposed adjacent to the polarizer through the suppression layer, the adhesion to the polarizer can be further improved.

In one embodiment, the functional group represented by X is preferably a functional group represented by Z-Y-, wherein Z represents a functional group comprising at least one reactive group selected from the group consisting of vinyl, (meth)acryl, styryl, (meth)acrylamide, vinyl ether, epoxy, cyclohexane, hydroxy, amino, aldehyde and carboxyl, and Y represents a phenylene group or an alkylene group.

As the copolymer monomer, the following compounds can be used specifically. [Chemical Formula 4] [Chemical formula 5]

The copolymerization monomer is used in an amount greater than 0 weight part and less than 50 weight parts relative to 100 weight parts of the monomer mixture, preferably greater than 0.01 weight part and less than 50 weight parts, more preferably 0.05 weight part to 20 weight parts, more preferably 0.1 weight part to 10 weight parts, and particularly preferably 0.5 weight part to 5 weight parts.

<Acrylic resin containing lactone ring, etc.> In another embodiment, the acrylic resin has a repeating unit containing a ring structure, and the repeating unit containing a ring structure is selected from a lactone ring unit, a glutaric anhydride unit, a glutarimide unit, a maleic anhydride unit, and a maleimide (N-substituted maleimide) unit. The repeating unit containing a ring structure may contain only one type in the repeating unit of the acrylic resin, or may contain two or more types.

The lactone ring unit is preferably represented by the following general formula (2):

[Chemical formula 6] In the general formula (2), R ² , R ³ and R ⁴ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. In addition, the organic residue may contain an oxygen atom. The acrylic resin may contain only a single lactone ring unit, or may contain a plurality of lactone ring units in which R ² , R ³ and R ⁴ in the general formula (2) are different. An acrylic resin having a lactone ring unit is described in, for example, Japanese Patent Application Publication No. 2008-181078, the contents of which are incorporated herein by reference.

The glutarimide unit is preferably represented by the following general formula (3):

[Chemical formula 7]

In the general formula (3), R ¹¹ and R ¹² each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ¹³ represents an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms. In the general formula (3), R ¹¹ and R ¹² each independently represent hydrogen or a methyl group, and R ¹³ represents hydrogen, a methyl group, a butyl group, or a cyclohexyl group. Preferably, R ¹¹ represents a methyl group, R ¹² represents hydrogen, and R ¹³ represents a methyl group. The acrylic resin may contain only a single pentylimide unit, or may contain a plurality of pentylimide units in which R ¹¹ , R ¹² , and R ¹³ in the general formula (3) are different. Acrylic resins having a glutarimide unit are described, for example, in Japanese Patent Application Laid-Open Nos. 2006-309033, 2006-317560, 2006-328334, 2006-337491, 2006-337492, 2006-337493, and 2006-337569, the contents of which are incorporated herein by reference. In addition, regarding the glutaric anhydride unit, the above description regarding the glutarimide unit is applicable except that the nitrogen atom substituted in R ¹³ in the above general formula (3) is replaced by an oxygen atom.

Regarding the maleic anhydride unit and the maleimide (N-substituted maleimide) unit, since the structures are clearly identified from the names, a specific description thereof will be omitted.

The content ratio of the repeating unit containing the ring structure in the acrylic resin is preferably 1 mol% to 50 mol%, preferably 10 mol% to 40 mol%, and more preferably 20 mol% to 30 mol%. Furthermore, the acrylic resin contains the repeating unit derived from the above-mentioned (meth) acrylic monomer as the main repeating unit.

The iodine penetration inhibition layer can be formed by applying an organic solvent solution of the above-mentioned resin to form a coating film, and the coating film is solidified or thermally cured. As for the organic solvent, any appropriate organic solvent that can dissolve or uniformly disperse the acrylic resin can be used. Specific examples of the organic solvent include: ethyl acetate, toluene, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone. The resin concentration of the solution is preferably 3 parts by weight to 20 parts by weight relative to 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film can be formed.

The solution can be applied to any appropriate substrate, and can also be applied to an adjacent layer (such as a polarizer, a phase difference layer). When the solution is applied to the substrate, the solidified product of the coating film formed on the substrate (iodine passes through the inhibition layer) is transferred to the adjacent layer. When the solution is applied to the adjacent layer, a protective layer can be directly formed on the adjacent layer by drying (curing) the coating film. It is preferred that the solution is applied to the adjacent layer and a protective layer is directly formed on the adjacent layer. If such a structure is used, the adhesive layer or the adhesive layer required for transfer can be omitted, so the polarizing plate with the phase difference layer can be further thinned. Any appropriate method may be used for applying the coating liquid. Specific examples include roller coating, spin coating, wire rod coating, dip coating, die coating, curtain coating, spray coating, knife coating (comma coating, etc.), and the like.

By curing or heat-hardening the coating film of the solution, an iodine transmission inhibition layer can be formed. The heating temperature for curing or heat-hardening is preferably below 100°C, preferably 50°C to 70°C. If the heating temperature is within such a range, adverse effects on the polarizer can be prevented. The heating time can be changed according to the heating temperature. The heating time can be, for example, 1 minute to 10 minutes.

The iodine permeation inhibition layer (substantially an organic solvent solution of the above resin) may contain any appropriate additives according to the purpose. Specific examples of additives include: ultraviolet absorbers; levelers; antioxidants such as hindered phenols, phosphorus, and sulfur; stabilizers such as light stabilizers, weather stabilizers, and heat stabilizers; reinforcing materials such as glass fibers and carbon fibers; near-infrared absorbers; tris(dibromopropyl)phosphate, triallylphosphite; Flame retardants such as acid salts, antimony oxide, etc.; antistatic agents such as anionic, cationic, and non-ionic surfactants; colorants such as inorganic pigments, organic pigments, and dyes; organic fillers or inorganic fillers; resin modifiers; organic fillers or inorganic fillers; plasticizers; lubricants; antistatic agents; flame retardants, etc. The type, amount, combination, and addition amount of additives can be appropriately set according to the purpose.

E. Another phase difference layer As described above, the other phase difference layer may 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 other phase difference layer, reflection in the tilt direction can be well prevented, and the anti-reflection function can be widened in viewing angle. At this time, the phase difference Rth(550) in the thickness direction of the other phase difference layer is preferably -50nm~-300nm, 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 completely equal, but also the case where nx and ny are substantially equal. That is, the in-plane phase difference Re(550) of the other phase difference layer can be less than 10nm.

Another phase difference layer having a refractive index characteristic of nz＞nx=ny can be formed of any appropriate material. Another phase difference layer is preferably composed of a film containing a liquid crystal material fixed in a vertical orientation. The vertically oriented liquid crystal material (liquid crystal compound) 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 can be exemplified by the liquid crystal compound and the method for forming the phase difference layer described in [0020] to [0028] of Japanese Patent Gazette No. 2002-333642. At this time, the thickness of the other phase difference layer is preferably 0.5μm~10μm, preferably 0.5μm~8μm, and more preferably 0.5μm~5μm.

F. Conductive layer or isotropic substrate with conductive layer The conductive layer can be formed by forming a metal oxide film on any appropriate substrate by any appropriate film forming method (such as vacuum evaporation, sputtering, CVD, ion plating, spraying, etc.). Regarding metal oxides, for example, indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, 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 above substrate to the phase difference layer (or the iodine-transmitting suppression layer or another phase difference layer if present) to form a constituent layer of the polarizing plate with phase difference layer as a single conductive layer, or can be laminated on the phase difference layer (or the iodine-transmitting suppression layer or another phase difference layer if present) as a laminate with the substrate (substrate with conductive layer). Preferably, the above substrate is optically isotropic, so the conductive layer can be used in the polarizing plate with phase difference layer in the form of an isotropic substrate with conductive layer.

Regarding the optically isotropic substrate (isotropic substrate), any appropriate isotropic substrate can be used. Regarding the materials constituting the isotropic substrate, for example, there can be listed: materials using resins without a conjugated system such as norbornene resins or olefin resins as the main skeleton, materials having a cyclic structure such as a lactone ring or a pentylimide ring in the main chain of an acrylic resin, etc. If such a material is used, the phase difference caused by the orientation of the molecular chain can be suppressed to a smaller level when forming the isotropic substrate. The thickness of the isotropic substrate is preferably less than 50 μm, and preferably less than 35 μm. The lower limit of the thickness of the isotropic substrate is, for example, 20 μm.

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

G. Image display device The polarizing plate with phase difference layer described in the above items A to F can be applied to an image display device. Therefore, the implementation form of the present invention includes an image display device using such a polarizing plate with phase difference layer. Representative examples of image display devices include: liquid crystal display devices, electroluminescent (EL) display devices (such as organic EL display devices, inorganic EL display devices). The image display device of the implementation form of the present invention is a polarizing plate with phase difference layer described in the above items A to F on its viewing side. The polarizing plate with phase difference layer is laminated in a manner such that the phase difference layer is on the side of the image display unit (such as a liquid crystal unit, an organic EL unit, an inorganic EL unit) (in a manner such that the polarizer is on the viewing side). Although such an image display device is very thin, it can significantly suppress corrosion of metal components. In one embodiment, the image display device may have a curved shape (essentially a curved display screen) and/or may be bent or folded. Example

The present invention is specifically described below by way of examples, but the present invention is not limited to these examples. The measuring methods of each characteristic are as follows. In addition, unless otherwise specified, the "parts" and "%" in the examples and comparative examples are based on weight.

(1) Thickness The thickness below 10μm is measured using an interferometer 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, product name "KC-351C").

(2) Metal Corrosion 1 A silver nanowire liquid (manufactured by MERCK, nanowire size: diameter 115nm, length 20μm~50μm, isopropyl alcohol (IPA) solution with a solid content of 0.5%) was applied to one side of a 50μm polyethylene terephthalate (PET) film using a wire rod to a wet film thickness of 15μm. The film was dried in an oven at 100℃ for 5 minutes to form a silver nanowire coating. Next, a wire rod was used to apply a coating protection solution (solid content concentration: about 1%) on the surface of the silver nanowire coating in a wet film thickness of 10 μm. The coating protection solution contained 99 parts of methyl isobutyl ketone (MIBK), 1 part of pentaerythritol tetraacrylate (PETA) and 0.03 parts of a photopolymerization initiator (manufactured by BASF, product name "IRGACURE 907"); then dried in an oven at 100°C for 5 minutes. Then, active energy rays were irradiated to cure the coating protection film, and a metal film with a structure of PET film/silver nanowire layer/covering layer (thickness 100 nm) was produced. The metal film was bonded to a 0.5 mm thick glass plate using an adhesive (15 μm) to obtain a metal film/adhesive/glass plate laminate. The resistance of the laminate was measured using a non-contact resistance meter (manufactured by Napson, product name "EC-80"), and the result was 50Ω/□.

The polarizing plate with phase difference layer obtained in the embodiment and the comparative example is attached to the surface of the protective layer covering the metal film of the laminate as a test sample. The resistance value of the test sample is measured by a non-contact resistance meter as the initial resistance value. Furthermore, after the test sample is subjected to a reliability test (after being placed in an environment of 85°C and 85%RH for 48 hours, and then placed in an environment of 23°C and 55%RH for 2 hours), the resistance value is measured in the same way as above. The resistance value increase rate is calculated by the following formula. Furthermore, when the measured value (resistance value) exceeds the measurement limit of the non-contact resistance meter (1000Ω/□), the measured value is assumed to be 1500Ω/□. Resistance value increase rate (%) = {(resistance value after reliability test - initial resistance value) / initial resistance value} × 100 Then, the evaluation is carried out according to the following criteria. ○: Resistance value increase rate is less than 200% ×: Resistance value increase rate is more than 200%

(3) Metal Corrosion 2 Using the same method as "(2) Metal Corrosion 1", the polarizing plate with phase difference layer obtained in the embodiment and the comparative example is attached to the surface of the metal film covering the protective layer of the laminate as a test sample. The resistance value of the test sample is measured using a non-contact resistance meter as the initial resistance value. The test sample is subjected to a reliability test (after being placed in an environment of 85°C and 85%RH for 200 hours, it is placed in an environment of 23°C and 55%RH for 2 hours). The following procedure is the same as "(2) Metal Corrosion 1", and the resistance value increase rate is calculated and evaluated according to the following criteria. ○: The resistance value increase rate is less than 200% △: The resistance value increase rate is more than 200% and less than 2000% ×: The resistance value increase rate is more than 2000%

(4) Peeling test The polarizing plate with phase difference layer obtained in the embodiment and the comparative example was cut into 50 mm × 50 mm pieces and attached to a glass plate with a larger cut size as a test sample. The test sample was placed in a constant temperature chamber adjusted to 20°C and 98% RH for 240 hours. After the test sample was taken out of the constant temperature chamber, a cross screwdriver was used to damage the polarizing plate with phase difference layer 3 mm from the corner, and an adhesive tape (manufactured by NICHIBAN, width 18 mm) was attached to the damaged part, and the polarizing plate with phase difference layer was peeled off from the glass at a high speed. The adhesive tape was pasted twice at one corner and peeled off to check the interlayer peeling of the polarizing plate with phase difference layer. The one without peeling at all four corners was evaluated as "○", and the one with peeling at one or more corners was evaluated as "×".

[Production Example 1: Preparation of boron-containing acrylic resin] 99.0 parts by weight of methyl methacrylate (MMA, manufactured by Fuji Film & Koshin Chemicals, trade name: methyl methacrylate monomer), 1.0 parts by weight of the monomer of the general formula (1e), and 0.2 parts by weight of a polymerization initiator (manufactured by Fuji Film & Koshin Chemicals, trade name: 2,2´-azobis(isobutyronitrile)) were dissolved in 100 parts by weight of toluene. Then, the mixture was heated to 70°C under a nitrogen atmosphere and a polymerization reaction was carried out for 5 hours to obtain a copolymer 1 (solid content concentration: 50% by weight). The Tg of the copolymer 1 was 110°C and the weight average molecular weight was 80,000.

[Manufacturing Example 2: Preparation of polarizing plate] 1. Preparation of polarizing element A long strip of amorphous isophthalic acid copolymerized polyethylene terephthalate film (thickness: 100 μm) with a water absorption rate of 0.75% and a Tg of about 75°C was used as a thermoplastic resin substrate. Corona treatment was performed on one side of the resin substrate. 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 was dissolved in water and 13 parts by weight of potassium iodide was added to 100 parts by weight of the PVA-based resin to prepare a PVA aqueous solution (coating solution). The above-mentioned PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60°C to form a PVA-based resin layer with a thickness of 13μm to produce a laminate. The obtained laminate was uniaxially stretched to 2.4 times at the free end in the longitudinal direction (length direction) between rollers with different peripheral speeds in a 130°C oven (air-assisted stretching treatment). Then, the laminate was immersed in an insolubilization 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 polarizer is immersed in a dyeing bath (an iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 to 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds (dyeing treatment) while adjusting the concentration so that the monomer transmittance (Ts) of the polarizer obtained finally becomes 43.0% or more (dyeing treatment). Next, it is 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 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 a boric acid aqueous solution (boric acid concentration 4.0 weight%, potassium iodide concentration 5 weight%) at a liquid temperature of 70°C, and uniaxially stretched in the longitudinal direction (length direction) between rollers with different peripheral speeds at a total stretching ratio of 5.5 times (underwater stretching treatment). Then, the laminate was immersed in a cleaning bath (aqueous solution prepared by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20°C (cleaning treatment). After that, it was dried in an oven maintained at 90°C and brought into contact with 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 due to the dry shrinkage treatment is 5.2%. Therefore, a polarizer with a thickness of 5μm is formed on the resin substrate.

2. Preparation of polarizing plate The surface of the polarizer obtained above (the side opposite to the resin substrate) is bonded with a HC-COP film as a protective layer via a UV-curable adhesive. Specifically, the curable adhesive is applied in such a way that the total thickness becomes 1.0 μm, and the bonding is performed using a roller press. Thereafter, UV rays are irradiated from the protective layer side to cure the adhesive. The HC-COP film is a film having a hard coating (HC) layer (2 μm thick) formed on a cycloolefin (COP) film (manufactured by ZEON Corporation of Japan, product name "ZF12", thickness 25 μm), and the film is bonded in such a way that the COP film is on the polarizer side. Next, the resin substrate is peeled off to obtain a polarizing plate having a structure of protective layer (HC layer/COP film)/adhesive layer/polarizer.

[Production Example 3: Production of the first oriented solidified layer and the second oriented solidified layer constituting the phase difference layer] 10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name "Paliocolor LC242", represented by the following formula) and 3 g of a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF: trade name "IRGACURE 907") were dissolved in 40 g of toluene to prepare a liquid crystal composition (coating liquid). [Chemical Formula 8] The surface of the polyethylene terephthalate (PET) film (thickness 38μm) is rubbed with a rubbing cloth to perform an orientation treatment. The direction of the orientation treatment is 15° relative to the absorption axis of the polarizer when attached to the polarizing plate, as viewed from the viewing side. The above-mentioned liquid crystal coating liquid is applied to the orientation-treated surface using a rod coater, and heated and dried at 90°C for 2 minutes to orient the liquid crystal compound. A metal halogen lamp is used to irradiate the liquid crystal layer thus formed with 1mJ/ ^cm2 of light to harden the liquid crystal layer, thereby forming a liquid crystal orientation solidification layer A on the PET film. The thickness of the liquid crystal orientation solidification layer A is 2.5μm, and the in-plane phase difference Re(550) is 270nm. Furthermore, the liquid crystal orientation solidification layer A has a refractive index distribution of nx＞ny=nz. In addition to changing the coating thickness and making the orientation treatment direction 75° relative to the absorption axis of the polarizer from the visual side, the liquid crystal orientation solidification layer B was formed on the PET film in the same manner as above. The thickness of the liquid crystal orientation solidification layer B was 1.5 μm, and the in-plane phase difference Re (550) was 140 nm. Furthermore, the liquid crystal orientation solidification layer B had a refractive index distribution of nx＞ny=nz.

[Example 1] The liquid crystal oriented solidified layer A and the liquid crystal oriented solidified layer B obtained in Example 3 are sequentially transferred to the surface of the polarizer of the polarizing plate obtained in Example 2. At this time, the transfer (bonding) is performed in such a way that the angle formed by the absorption axis of the polarizer and the slow axis of the liquid crystal oriented solidified layer A is 15°, and the angle formed by the absorption axis of the polarizer and the slow axis of the liquid crystal oriented solidified layer B is 75°. Furthermore, each transfer (bonding) is performed through the ultraviolet curing adhesive (thickness 1.0μm) used in Example 2. In this way, a laminate having a structure of protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive layer/phase difference layer (first liquid crystal oriented solidification layer/adhesive layer/second liquid crystal oriented solidification layer) is produced.

To 95 parts of a blend of 15 parts (converted to solid content) of copolymer 1 (boron-containing acrylic resin) obtained in Production Example 1 and 85 parts (converted to solid content) of a thermoplastic epoxy resin (manufactured by Mitsubishi Chemical Co., Ltd., trade name "jER (registered trademark) YX6954BH30"), 5 parts of an isocyanate compound (manufactured by Tosoh Corporation, "CORONATE L": trihydroxymethylpropane adduct of toluene diisocyanate) were added. The Tg of the resin blend was 125°C and the weight average molecular weight was 46,000. The mixture was dissolved in 80 parts of a mixed solvent of ethyl acetate/cyclopentanone (70/30) to obtain a resin solution (20%). The resin solution was applied to the surface of the second liquid crystal orientation solidified layer of the laminate obtained above using a wire rod, and the coating film was dried at 60°C for 5 minutes to form an iodine transmission inhibition layer (thickness 0.5μm) composed of a cured product of the coating film of the resin organic solvent solution. Then, an adhesive layer (thickness 15μm) was set on the surface of the iodine transmission inhibition layer to obtain a polarizing plate with a phase difference layer having a structure of protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive layer/phase difference layer (first liquid crystal orientation solidified layer/adhesive layer/second liquid crystal orientation solidified layer)/iodine transmission inhibition layer/adhesive layer. The total thickness of the obtained polarizing plate with phase difference layer is 39.5 μm. The obtained polarizing plate with phase difference layer is evaluated in the above (2) to (4). The results are shown in Table 1.

[Example 2] A polarizing plate with a phase difference layer was prepared in the same manner as in Example 1, except that a mixture of 90 parts of an isocyanate compound added to 10 parts of a resin blend was used to form an iodine transmission inhibition layer. The obtained polarizing plate with a phase difference layer was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 3] Except that an iodine transmission inhibition layer is formed by adding 20 parts of an isocyanate compound to 80 parts of a resin admixture, and the iodine transmission inhibition layer is formed between the polarizer and the first liquid crystal orientation solidification layer, a polarizing plate with a phase difference layer having a structure of protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive layer/iodine transmission inhibition layer/phase difference layer (first liquid crystal orientation solidification layer/adhesive layer/second liquid crystal orientation solidification layer)/adhesive layer is prepared in the same manner as in Example 1. The obtained polarizing plate with a phase difference layer is evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 4] A polarizing plate with a phase difference layer was prepared in the same manner as in Example 1, except that a mixture of 20 parts of an isocyanate compound added to 80 parts of copolymer 1 (boron-containing acrylic resin) was used to form an iodine transmission suppression layer. The obtained polarizing plate with a phase difference layer was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 5] A polarizing plate with a phase difference layer was prepared in the same manner as in Example 1, except that a mixture of 20 parts of an isocyanate compound added to 80 parts of a thermoplastic epoxy resin (manufactured by Mitsubishi Chemical Co., Ltd., trade name "jER (registered trademark) YX6954BH30") was used to form an iodine transmission suppression layer. The epoxy resin had a Tg of 130°C and a weight average molecular weight of 38,000. The obtained polarizing plate with a phase difference layer was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 6] A polarizing plate with a phase difference layer was prepared in the same manner as in Example 5, except that "jER (registered trademark) YX7200B35" manufactured by Mitsubishi Chemical Co., Ltd. was used as a thermoplastic epoxy resin to form the iodine transmission suppression layer instead of "YX6954BH30". The epoxy resin has a Tg of 150°C and a weight average molecular weight of 30,000. The obtained polarizing plate with a phase difference layer was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 7] A polarizing plate with a phase difference layer was prepared in the same manner as in Example 1, except that a mixture of 20 parts of an isocyanate compound (manufactured by Tosoh Corporation, "CORONATE 2067": trihydroxymethylpropane adduct of diphenylmethane diisocyanate) was added to 80 parts of the resin blend to form an iodine transmission suppression layer. The obtained polarizing plate with a phase difference layer was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 8] A polarizing plate with a phase difference layer was prepared in the same manner as in Example 1, except that a mixture of 20 parts of an isocyanate compound ("TAKENATE D110N": trihydroxymethylpropane adduct of m-xylene diisocyanate, manufactured by Mitsui Chemicals, Inc.) was added to 80 parts of the resin blend to form an iodine transmission suppression layer. The obtained polarizing plate with a phase difference layer was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 9] Except that an iodine transmission inhibition layer using only copolymer 1 (i.e., not containing isocyanate compounds) is further formed between the polarizer and the first liquid crystal orientation solidification layer, a polarizing plate with a phase difference layer having a structure of protective layer (HC layer/COP film)/adhesive layer/polarizer/iodine transmission inhibition layer/adhesive layer/phase difference layer (first liquid crystal orientation solidification layer/adhesive layer/second liquid crystal orientation solidification layer)/iodine transmission inhibition layer/adhesive layer is prepared in the same manner as in Example 3. The obtained polarizing plate with a phase difference layer is evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 10] Except that an iodine transmission inhibition layer similar to that of Example 3 is further formed between the polarizer and the first liquid crystal orientation solidification layer, a polarizing plate with a phase difference layer having a structure of protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive layer/iodine transmission inhibition layer/phase difference layer (first liquid crystal orientation solidification layer/adhesive layer/second liquid crystal orientation solidification layer)/iodine transmission inhibition layer/adhesive layer is prepared in the same manner as in Example 3. The obtained polarizing plate with a phase difference layer is evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 11] In addition to further forming an iodine transmission inhibition layer using only copolymer 1 (i.e., not containing isocyanate compounds) and an iodine transmission inhibition layer identical to Example 3 between the polarizer and the first liquid crystal orientation solidification layer in order from the polarizer side, a polarizing plate with a phase difference layer having a structure of protective layer (HC layer/COP film)/adhesive layer/polarizer/iodine transmission inhibition layer/adhesive layer/iodine transmission inhibition layer/phase difference layer (first liquid crystal orientation solidification layer/adhesive layer/second liquid crystal orientation solidification layer)/iodine transmission inhibition layer/adhesive layer was prepared in the same manner as in Example 3. The obtained polarizing plate with a phase difference layer was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1] Except that the iodine transmission inhibition layer is not formed, a polarizing plate with a phase difference layer having a structure of protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive layer/phase difference layer (first liquid crystal oriented solidification layer/adhesive layer/second liquid crystal oriented solidification layer)/adhesive layer is prepared in the same manner as in Example 1. The obtained polarizing plate with a phase difference layer is evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2] A polarizing plate with a phase difference layer was prepared in the same manner as in Example 1 except that an iodine transmission suppression layer was formed using only an acrylic resin ("B-723" manufactured by Kusumoto Chemicals Co., Ltd., Tg: 54°C, Mw: 200,000) (i.e., not containing an isocyanate compound). The obtained polarizing plate with a phase difference layer was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 3] Except for forming an iodine transmission suppression layer using only a resin admixture (i.e., not containing an isocyanate compound), a polarizing plate with a phase difference layer was prepared in the same manner as in Example 1. The obtained polarizing plate with a phase difference layer was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 4] A polarizing plate with a phase difference layer was prepared in the same manner as in Example 1, except that a mixture of 20 parts of an isocyanate compound ("TAKENATE D160N": trihydroxymethylpropane adduct of hexamethylene diisocyanate, manufactured by Mitsui Chemicals, Inc.) was added to 80 parts of the resin blend to form an iodine transmission suppression layer. The obtained polarizing plate with a phase difference layer was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Table 1]

Furthermore, in Table 1, "Epoxy/Acrylic" in the column of the constituent resin indicates a blend of epoxy resin and acrylic resin; and the numbers in the column of the forming position indicate the graphic symbols. Thus, for example, "11" indicates a polarizer.

[Evaluation] It can be seen from Table 1 that the polarizing plate with a phase difference layer of the embodiment of the present invention can significantly suppress metal corrosion in a high temperature and high humidity environment. Therefore, it can be seen that when the polarizing plate with a phase difference layer of the embodiment of the present invention is used in an image display device, it can suppress the corrosion of metal components. Furthermore, if Examples 1 to 8 are compared with Examples 9 to 11, it can be seen that by providing more than two layers of iodine transmission inhibition layers, metal corrosion can be significantly suppressed. In addition, the polarizing plate with a phase difference layer of the embodiment of the present invention can suppress the peeling of the iodine transmission inhibition layer and the phase difference layer. Industrial applicability

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

10: Polarizing plate 11: Polarizing element 12: Protective layer 20: Phase difference layer 21: First liquid crystal directional solidification layer 22: Second liquid crystal directional solidification layer 30: Adhesive layer 40: Iodine transmission inhibition layer 100: Polarizing plate with phase difference layer 101: Polarizing plate with phase difference layer 102: Polarizing plate with phase difference layer 103: Polarizing plate with phase difference layer 104: Polarizing plate with phase difference layer 105: Polarizing plate with phase difference layer 106: Polarizing plate with phase difference layer 107: Polarizing plate with phase difference layer 108: Polarizing plate with phase difference layer 109: Polarizing plate with phase difference layer

FIG. 1A is a schematic cross-sectional view of a polarizing plate with a phase difference layer in one embodiment of the present invention. FIG. 1B is a schematic cross-sectional view of a polarizing plate with a phase difference layer in another embodiment of the present invention. FIG. 1C is a schematic cross-sectional view of a polarizing plate with a phase difference layer in another embodiment of the present invention. FIG. 1D is a schematic cross-sectional view of a polarizing plate with a phase difference layer in another embodiment of the present invention. FIG. 2A is a schematic cross-sectional view of a polarizing plate with a phase difference layer in another embodiment of the present invention. FIG. 2B is a schematic cross-sectional view of a polarizing plate with a phase difference layer in another embodiment of the present invention. FIG. 2C is a schematic cross-sectional view of a polarizing plate with a phase difference layer in another embodiment of the present invention. FIG2D is a schematic cross-sectional view of a polarizing plate with a phase difference layer in another embodiment of the present invention. FIG2E is a schematic cross-sectional view of a polarizing plate with a phase difference layer in another embodiment of the present invention. FIG2F is a schematic cross-sectional view of a polarizing plate with a phase difference layer in another embodiment of the present invention.

10: Polarizing plate

11: Polarizer

12: Protective layer

20: Phase difference layer

30: Adhesive layer

40: Iodine penetration inhibition layer

100: Polarizing plate with phase difference layer

Claims (13)

A polarizing plate with a phase difference layer comprises, from the viewing side, a polarizing plate including a polarizer, a phase difference layer and an adhesive layer in order; at least one iodine transmission inhibition layer is disposed between the polarizer and the adhesive layer, the iodine transmission inhibition layer being a cured product or a thermally cured product of a coating film of an organic solvent solution of a resin; the iodine transmission inhibition layer adjacent to the phase difference layer comprises a resin and an isocyanate compound; The glass transition temperature of the resin is above 85°C, and the weight average molecular weight Mw is above 25,000; the isocyanate compound is at least one selected from toluene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate and their derivatives; the content ratio of the resin to the isocyanate compound (resin/isocyanate compound) is 95/5~10/90. As in claim 1, the polarizing plate with a phase difference layer, wherein the aforementioned iodine transmission suppression layer is provided with two or more layers. As in claim 2, the polarizing plate with a phase difference layer, wherein at least one of the two or more iodine transmission suppression layers is disposed adjacent to the phase difference layer. As in claim 2, the polarizing plate with a phase difference layer, wherein one of the two or more iodine transmission suppression layers is disposed adjacent to the polarizing element. A polarizing plate with a phase difference layer as claimed in any one of claims 1 to 4, wherein the thickness of the iodine transmission suppression layer is 0.05μm~10μm. A polarizing plate with a phase difference layer as claimed in any one of claims 1 to 4, wherein the resin constituting the aforementioned iodine transmission suppression layer comprises an epoxy resin. A polarizing plate with a phase difference layer as claimed in any one of claims 1 to 4, wherein the resin constituting the iodine transmission suppression layer comprises a copolymer obtained by polymerizing a monomer mixture, wherein the monomer mixture comprises greater than 50 parts by weight of a (meth)acrylic monomer and greater than 0 parts by weight and less than 50 parts by weight of a monomer represented by formula (1):

(wherein X represents a functional group, and the functional group includes at least one reactive group selected from the group consisting of vinyl, (meth)acryl, styryl, (meth)acrylamide, vinyl ether, epoxy, cyclohexane, hydroxy, amino, aldehyde and carboxyl groups; ^R1 and ^R2 independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent; ^R1 and ^R2 may be linked to each other to form a ring). A polarizing plate with a phase difference layer as claimed in any one of claims 1 to 4, wherein the phase difference layer is an oriented solidified layer of a liquid crystal compound having a circular polarization function or an elliptical polarization function. A polarizing plate with a phase difference layer as claimed in any one of claims 1 to 4, wherein the phase difference layer is a single layer, the Re (550) of the phase difference layer is 100nm~190nm, and the angle formed by the slow axis of the phase difference layer and the absorption axis of the polarizer is 40°~50°. A polarizing plate with a phase difference layer as claimed in any one of claims 1 to 4, wherein 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 polarizer 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 polarizer is 70°~80°. For the polarizing plate with phase difference layer as in any of claims 1 to 4, the total thickness is less than 60μm. An image display device having a polarizing plate with a phase difference layer as in any one of claims 1 to 11. The image display device of claim 12 is an organic electroluminescent display device or an inorganic electroluminescent display device.

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