JP7273768B2 - Polarizing plate, polarizing plate with retardation layer, and image display device using these - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polarizing plate, a polarizing plate with a retardation layer, and an image display device using these.

2. Description of the Related Art In recent years, image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices (eg, organic EL display devices and inorganic EL display devices) have rapidly spread. Polarizing plates and retardation plates are typically used in image display devices. Practically, a polarizing plate with a retardation layer in which a polarizing plate and a retardation plate are integrated is widely used (for example, Patent Document 1). Accordingly, there is an increasing demand for thinner polarizing plates and polarizing plates with retardation layers. However, a thin polarizing plate and a polarizing plate with a retardation layer have a problem that their optical properties (typically, the degree of polarization) change greatly in a high-temperature and high-humidity environment, and their durability is insufficient.

Japanese Patent No. 3325560

The present invention has been made to solve the conventional problems described above, and a main object thereof is to provide a thin polarizing plate and a retardation layer-attached polarizing plate having excellent durability in a high-temperature and high-humidity environment. It is in.

（式中、Ｘはビニル基、（メタ）アクリル基、スチリル基、（メタ）アクリルアミド基、ビニルエーテル基、エポキシ基、オキセタン基、ヒドロキシル基、アミノ基、アルデヒド基、および、カルボキシル基からなる群より選択される少なくとも１種の反応性基を含む官能基を表し、Ｒ^１およびＲ^２はそれぞれ独立して、水素原子、置換基を有していてもよい脂肪族炭化水素基、置換基を有していてもよいアリール基、または、置換基を有していてもよいヘテロ環基を表し、Ｒ^１およびＲ^２は互いに連結して環を形成してもよい）。
本発明の別の局面によれば、位相差層付偏光板が提供される。この位相差層付偏光板は、上記の偏光板と、上記偏光子と上記粘着剤層との間に配置された位相差層と、を有する。該位相差層は円偏光機能または楕円偏光機能を有する液晶化合物の配向固化層である。
１つの実施形態においては、上記位相差層は単一層であり、該位相差層のＲｅ（５５０）は１００ｎｍ～１９０ｎｍであり、該位相差層の遅相軸と上記偏光子の吸収軸とのなす角度は４０°～５０°である。
１つの実施形態においては、上記位相差層は、第１の液晶化合物の配向固化層と第２の液晶化合物の配向固化層との積層構造を有し；該第１の液晶化合物の配向固化層のＲｅ（５５０）は２００ｎｍ～３００ｎｍであり、その遅相軸と上記偏光子の吸収軸とのなす角度は１０°～２０°であり；該第２の液晶化合物の配向固化層のＲｅ（５５０）は１００ｎｍ～１９０ｎｍであり、その遅相軸と該偏光子の吸収軸とのなす角度は７０°～８０°である。
１つの実施形態においては、上記位相差層付偏光板は、総厚みが６０μｍ以下である。
本発明のさらに別の局面によれば、画像表示装置が提供される。この画像表示装置は、上記の偏光板または位相差層付偏光板を備える。
１つの実施形態においては、上記画像表示装置は、有機エレクトロルミネセンス表示装置または無機エレクトロルミネセンス表示装置である。 The polarizing plate of the present invention has a polarizer, an iodine permeation suppressing layer and an adhesive layer in this order. The iodine abundance index of the adhesive layer is 0.050 or less.
In one embodiment, the iodine permeation suppressing layer is a solidified product or thermoset product of a coating film of an organic solvent solution of a resin. In one embodiment, the resin constituting the iodine permeation suppressing layer has a glass transition temperature of 85° C. or higher and a weight average molecular weight Mw of 25000 or higher.
In one embodiment, two or more layers of the iodine permeation suppressing layer are provided between the polarizer and the pressure-sensitive adhesive layer.
In one embodiment, the iodine permeation suppression layer has a thickness of 0.05 μm to 10 μm.
In one embodiment, the resin constituting the iodine permeation suppressing layer is represented by the formula (1) containing more than 50 parts by weight of (meth)acrylic monomer and more than 0 parts by weight and less than 50 parts by weight. including copolymers obtained by polymerizing a monomer mixture containing the monomers:

(Wherein, X is a vinyl group, a (meth)acryl group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetane group, a hydroxyl group, an amino group, an aldehyde group, and a group consisting of a carboxyl group Represents a selected functional group containing at least one reactive group, and R ¹ and R ² each independently represent a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, or a substituted or an optionally substituted heterocyclic group, and R ¹ and R ² may be linked together to form a ring).
According to another aspect of the present invention, a polarizing plate with a retardation layer is provided. This retardation layer-attached polarizing plate has the above polarizing plate and a retardation layer disposed between the polarizer and the pressure-sensitive adhesive layer. The retardation layer is an alignment fixed layer of a liquid crystal compound having a circularly polarized light function or an elliptically polarized light function.
In one embodiment, the retardation layer is a single layer, Re (550) of the retardation layer is 100 nm to 190 nm, and the slow axis of the retardation layer and the absorption axis of the polarizer The angle formed is 40° to 50°.
In one embodiment, the retardation layer has a laminated structure of a first fixed alignment layer of a liquid crystal compound and a second fixed alignment layer of a liquid crystal compound; the first fixed alignment layer of a liquid crystal compound. is 200 nm to 300 nm, and the angle formed by the slow axis and the absorption axis of the polarizer is 10° to 20°; ) is 100 nm to 190 nm, and the angle between the slow axis and the absorption axis of the polarizer is 70° to 80°.
In one embodiment, the retardation layer-attached polarizing plate has a total thickness of 60 μm or less.
According to still another aspect of the present invention, an image display device is provided. This image display device includes the polarizing plate or the polarizing plate with a retardation layer.
In one embodiment, the image display device is an organic electroluminescence display device or an inorganic electroluminescence display device.

According to an embodiment of the present invention, by providing a specific iodine permeation suppression layer to control the iodine existence index of the pressure-sensitive adhesive layer, a thin polarizing plate and a retardation plate having excellent durability in a high-temperature and high-humidity environment A layered polarizing plate can be realized. The iodine permeation suppressing layer that can be used in the embodiment of the present invention is a solidified or thermoset product of a coating film of a resin in an organic solvent solution, and the glass transition temperature of the resin constituting the iodine permeation suppressing layer is 85° C. or higher. and the weight average molecular weight Mw is 25000 or more, and the iodine existence index of the adhesive layer in the embodiment of the present invention is 0.050 or less.

1 is a schematic cross-sectional view of a polarizer according to one embodiment of the invention; FIG. 1 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention; FIG. FIG. 4 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to another embodiment of the invention; FIG. 4 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to still another embodiment of the present invention; FIG. 4 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to still another embodiment of the present invention; FIG. 4 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to still another embodiment of the present invention; FIG. 4 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to still another embodiment of the present invention;

Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

(Definition of terms and symbols)
Definitions of terms and symbols used herein are as follows.
(1) refractive index (nx, ny, nz)
"nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., slow axis direction), and "ny" is the in-plane direction orthogonal to the slow axis (i.e., fast axis direction) and "nz" is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
“Re(λ)” is an in-plane retardation measured at 23° C. with light having a wavelength of λ nm. For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 550 nm at 23°C. Re(λ) is obtained by the formula: Re(λ)=(nx−ny)×d, where d (nm) is the thickness of the layer (film).
(3) Thickness direction retardation (Rth)
“Rth(λ)” is the retardation in the thickness direction measured at 23° C. with light having a wavelength of λ nm. For example, “Rth(550)” is the retardation in the thickness direction measured at 23° C. with light having a wavelength of 550 nm. Rth(λ) is determined by the formula: Rth(λ)=(nx−nz)×d, where d (nm) is the thickness of the layer (film).
(4) Nz Coefficient The Nz coefficient is obtained by Nz=Rth/Re.
(5) Angle When referring to an angle in this specification, the angle includes both clockwise and counterclockwise directions with respect to a reference direction. Thus, for example, "45°" means ±45°.

A. Polarizing plate A-1. Overall Configuration of Polarizing Plate FIG. 1 is a schematic cross-sectional view of a polarizing plate according to one embodiment of the present invention. Polarizing plate 10 typically has protective layer 12, polarizer 11, iodine permeation suppressing layer 40, and adhesive layer 30 in this order. Depending on the purpose, another protective layer (not shown) may be provided on the opposite side of the polarizer 11 from the protective layer 12 . The pressure-sensitive adhesive layer 30 is provided as the outermost layer, and the polarizing plate can be attached to an image display device (substantially, an image display cell). The polarizing plate may be used as a viewing-side polarizing plate or as a back-side polarizing plate in an image display device.

In the embodiment of the present invention, the iodine permeation suppression layer 40 is provided between the polarizer 11 and the adhesive layer 30 as described above. The iodine permeation suppressing layer is typically a solidified or thermoset coating film of a resin solution in an organic solvent. Further, the glass transition temperature (Tg) of the resin constituting the iodine permeation suppressing layer is, for example, 85° C. or higher, and the weight average molecular weight Mw is, for example, 25,000 or higher. By providing such an iodine permeation suppressing layer at a predetermined position of the polarizing plate, iodine in the polarizer is transferred to the pressure-sensitive adhesive layer (eventually an image display device, substantially an image display cell) in a high-temperature and high-humidity environment. ) can be remarkably suppressed. As a result, a thin polarizing plate (details will be described later) can achieve excellent durability in a high-temperature and high-humidity environment. Furthermore, when the polarizing plate is applied to an image display device, corrosion of metal members (e.g., electrodes, sensors, wiring, metal layers) of the image display device can be significantly suppressed, and in a high-temperature and high-humidity environment An increase in reflectance can be suppressed. Such effects are unique to thin polarizing plates. That is, the present inventors have found the above-described polarizing plate as a means for preventing the migration of iodine, which is one of the factors of the change in the optical properties (typically, the degree of polarization) of a thin polarizing plate in a high-temperature and high-humidity environment. An iodine permeation suppression layer (a solidified layer or a thermosetting layer of a coating film of an organic solvent solution of a resin having a specific Tg and Mw) is provided, and the iodine abundance index (described later) of the adhesive layer is set to 0.050 or less. We have found that this is useful, and have completed the present invention. Furthermore, as will be described later, the iodine permeation suppressing layer can be formed very thin, and by providing the iodine permeation suppressing layer, the protective layer on the side opposite to the viewing side can be omitted. This effect can contribute to further thinning of the polarizing plate.

In the retardation layer-attached polarizing plate, two or more iodine permeation suppressing layers may be provided between the polarizer and the pressure-sensitive adhesive layer (eg, FIGS. 5 and 6). Since the polarizing plate with a retardation layer has two or more iodine permeation suppression layers, corrosion of metal members can be significantly suppressed when the polarizing plate with a retardation layer is applied to an image display device.

In the retardation layer-attached polarizing plate shown in FIG. 4, two iodine permeation suppression layers are provided between the polarizer and the pressure-sensitive adhesive layer. In the example shown in FIG. 5, two iodine permeation suppression layers are provided between the polarizer 11 and the retardation layer 20 and between the retardation layer 20 and the adhesive layer 30 . In one embodiment, the iodine permeation suppression layer is provided adjacent to the polarizer. In another embodiment, the iodine permeation suppression layer is provided adjacent to the retardation layer. As used herein, "adjacent" means being directly laminated without an adhesive layer or the like intervening.

In the retardation layer-attached polarizing plate shown in FIG. 6, three iodine permeation suppression layers are provided between the polarizer and the adhesive layer. In the example shown in FIG. 6, two iodine permeation suppression layers are provided between the polarizer 11 and the retardation layer 20, and one layer is provided between the retardation layer 20 and the adhesive layer 30. ing. Of the two iodine permeation suppression layers between the polarizer 11 and the retardation layer 20, one is provided adjacent to the polarizer and the other is provided adjacent to the retardation layer.

In the retardation layer-attached polarizing plate, the number of iodine permeation suppressing layers may be 4 or more (for example, 4, 5, or 6 layers). As the number of iodine permeation suppression layers increases, the metal corrosion suppression effect can be enhanced. The number of iodine permeation suppressing layers can be set in consideration of cost, production efficiency, total thickness of the retardation layer-attached polarizing plate, and the like.

In the embodiment of the present invention, as described above, the iodine existence index of the adhesive layer 30 is 0.050 or less. The iodine abundance index is preferably 0.040 or less, more preferably 0.030 or less, still more preferably 0.020 or less, and particularly preferably 0.015 or less. The smaller the iodine abundance index, the better, ideally it is zero, and its lower limit can be, for example, 0.001. The iodine existence index is an index of the amount of iodine that has migrated from the polarizer to the adhesive layer in a high-temperature, high-humidity environment. indicates that the change in is small. Therefore, if the iodine existence index is within such a range, migration of iodine is suppressed, and excellent durability in a high-temperature and high-humidity environment can be achieved in a thin polarizing plate (details will be described later). The iodine abundance index is a secondary ion mass spectrometry (TOF -SIMS). More specifically, the iodine abundance index is determined by TOF-SIMS measurement of the adhesive layer surface after the reliability test, and among the obtained negative secondary ions, C ₃ H ₃ O ₂ derived from acrylic (adhesive). ⁻ (m/z=71) and the ionic strength of I ⁻ (m/z=127) derived from iodine can be extracted and calculated using the following formula.
Iodine abundance index = I ^- ionic strength/C ₃ H ₃ O ₂ ^- ionic strength Note that since the adhesive layer 30 may adopt a configuration well known in the industry, the detailed configuration of the adhesive layer is omitted. .

The polarizing plate according to the embodiment of the present invention may be sheet-shaped or elongated. As used herein, the term "long shape" means an elongated shape whose length is sufficiently long relative to its width, for example, an elongated shape whose length is 10 times or more, preferably 20 times or more, its width. include. A long polarizing plate can be wound into a roll.

The total thickness of the polarizing plate is preferably 45 μm or less, more preferably 40 μm or less, still more preferably 35 μm or less, and particularly preferably 30 μm or less. A lower limit for the total thickness can be, for example, 22 μm. According to the embodiment of the present invention, such an extremely thin polarizing plate can be realized, and furthermore, such an extremely thin polarizing plate can realize excellent durability in a high-temperature and high-humidity environment. Also, such a polarizing plate can have excellent flexibility and bending durability. Therefore, such a polarizing plate can be applied particularly preferably to a curved image display device and/or a bendable or foldable image display device. The total thickness of the polarizing plate refers to the total thickness of the polarizer, the protective layer, the iodine permeation suppressing layer, and the adhesive layer or pressure-sensitive adhesive layer for laminating them (that is, the total thickness of the polarizing plate is It does not include the pressure-sensitive adhesive layer 30 and the thickness of the release film that can be temporarily adhered to its surface).

Practically, it is preferable that a release film is temporarily attached to the surface of the pressure-sensitive adhesive layer 30 until the polarizing plate is used. By temporarily attaching the release film, it is possible to protect the pressure-sensitive adhesive layer and to form a roll of the polarizing plate.

A-2. Polarizer A polarizer is typically composed of a polyvinyl alcohol (PVA) resin film containing a dichroic substance. The thickness of the polarizer is preferably 1 μm to 8 μm, more preferably 1 μm to 7 μm, still more preferably 2 μm to 5 μm. If the thickness of the polarizer is within such a range, it can greatly contribute to making the polarizing plate thinner. Furthermore, the effect of the present invention is remarkable in a thin polarizing plate using such a polarizer.

The boric acid content of the polarizer is preferably 10% by weight or more, more preferably 13% to 25% by weight. If the boric acid content of the polarizer is within such a range, the easiness of curl adjustment during lamination can be maintained satisfactorily due to the synergistic effect with the iodine content described later, and the curl during heating can be reduced. It is possible to improve the appearance durability during heating while satisfactorily suppressing the The boric acid content can be calculated as the amount of boric acid contained in the polarizer per unit weight, for example, using the following formula from the neutralization method.

The iodine content of the polarizer is preferably 2% by weight or more, more preferably 2% to 10% by weight. If the iodine content of the polarizer is within such a range, the synergistic effect with the above-mentioned boric acid content can maintain the ease of curl adjustment during bonding and prevent curl during heating. It is possible to improve the appearance durability during heating while satisfactorily suppressing the As used herein, "iodine content" means the total amount of iodine contained in the polarizer (PVA-based resin film). More specifically, iodine exists in the form of iodine ions (I ⁻ ), iodine molecules (I ₂ ), polyiodine ions (I ₃ ⁻ , I ₅ ⁻ ) and the like in the polarizer. The iodine content means the amount of iodine including all these forms. The iodine content can be calculated, for example, by a calibration curve method of fluorescent X-ray analysis. The polyiodine ions are present in the polarizer in the form of a PVA-iodine complex. Absorption dichroism can be expressed in the visible light wavelength range by forming such a complex. Specifically, the complex of PVA and triiodide ion (PVA·I ₃ ⁻ ) has an absorption peak near 470 nm, and the complex of PVA and pentaiodide ion (PVA·I ₅ ⁻ ) has an absorption peak near 600 nm. has an absorption peak at As a result, polyiodine ions can absorb light in a wide range of visible light, depending on their morphology. On the other hand, iodine ions (I ⁻ ) have an absorption peak near 230 nm and are not substantially involved in the absorption of visible light. Therefore, polyiodine ions present in a complex with PVA may be primarily responsible for the absorption performance of the polarizer.

The polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance Ts of the polarizer is preferably 40% to 48%, more preferably 41% to 46%. The degree of polarization P of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, still more preferably 99.9% or more. The single transmittance is typically a Y value measured using an ultraviolet-visible spectrophotometer and subjected to visibility correction. The degree of polarization is typically obtained by the following formula based on the parallel transmittance Tp and the orthogonal transmittance Tc measured using an ultraviolet-visible spectrophotometer and subjected to visibility correction.
Degree of polarization (%) = {(Tp-Tc)/(Tp+Tc)} ^1/2 × 100

A polarizer can typically be made using a laminate of two or more layers. A specific example of a polarizer obtained using a laminate is a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate. A polarizer obtained by using a laminate of a resin base material and a PVA-based resin layer formed by coating on the resin base material is obtained, for example, by applying a PVA-based resin solution to the resin base material and drying the resin base material. forming a PVA-based resin layer thereon to obtain a laminate of a resin substrate and a PVA-based resin layer; stretching and dyeing the laminate to use the PVA-based resin layer as a polarizer; obtain. Stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Furthermore, stretching may further include stretching the laminate in air at a high temperature (eg, 95° C. or higher) before stretching in an aqueous boric acid solution, if necessary. The obtained resin substrate/polarizer laminate may be used as it is (that is, the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate/polarizer laminate. Then, any appropriate protective layer may be laminated on the release surface according to the purpose. Details of the method for manufacturing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. These publications are incorporated herein by reference in their entireties.

A typical method for producing a polarizer is to form a laminate by forming a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin on one side of a long thermoplastic resin substrate, Then, the laminate is subjected in this order to an in-air auxiliary stretching process, a dyeing process, an underwater stretching process, and a drying shrinkage process that shrinks the laminate by 2% or more in the width direction by heating while being transported in the longitudinal direction. including. As a result, it is possible to provide a polarizer that is extremely thin, has excellent optical properties, and has suppressed variations in optical properties. That is, by introducing auxiliary stretching, it is possible to improve the crystallinity of PVA even when PVA is coated on a thermoplastic resin, and to achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as deterioration of orientation and dissolution of PVA when immersed in water in the subsequent dyeing process or stretching process, resulting in high optical properties. can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, disturbance of the orientation of the polyvinyl alcohol molecules and deterioration of the orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. This can improve the optical properties of the polarizer obtained through treatment steps such as dyeing treatment and underwater stretching treatment in which the laminate is immersed in a liquid. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction by drying shrinkage treatment.

A-3. Protective Layer Protective layer 12 is 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-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based resins. , polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based, and acetate-based transparent resins. Thermosetting resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone, or ultraviolet curable resins may also be used. In addition, for example, a glassy polymer such as a siloxane-based polymer can also be used. Further, polymer films described in JP-A-2001-343529 (WO01/37007) can also be used. Materials for this film include, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in a side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in a side chain. can be used, for example, a resin composition comprising an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer. The polymer film can be, for example, an extrudate of the resin composition.

The polarizing plate is placed on the viewing side of the image display device in one embodiment, and the protective layer 12 is typically placed on that viewing side. In such a case, the protective layer 12 may be subjected to surface treatment such as hard coat treatment, anti-reflection treatment, anti-sticking treatment, anti-glare treatment, etc., if necessary. Further/or, the protective layer 12 may optionally be treated to improve visibility when viewed through polarized sunglasses (typically, imparting (elliptical) polarizing function, ultra-high retardation ) may be applied. By performing such processing, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the polarizing plate can be suitably applied to an image display device 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. In addition, when the surface treatment is performed, the thickness of the outer protective layer is the thickness including the thickness of the surface treatment layer.

A-4. Iodine Permeation Suppressing Layer As described above, the iodine permeation suppressing layer is a solidified product or a heat-cured product of a coating film of a resin in an organic solvent solution. With such a configuration, the thickness can be made very thin (for example, 10 μm or less). The thickness of the iodine permeation suppressing layer is preferably 0.05 μm to 10 μm, more preferably 0.08 μm to 5 μm, even more preferably 0.1 μm to 1 μm, particularly preferably 0.2 μm to 0.7 μm. is. Furthermore, with such a configuration, the iodine permeation suppression layer can be formed directly on the polarizer (that is, without an adhesive layer or pressure-sensitive adhesive layer interposed). According to the embodiment of the present invention, as described above, the polarizer and the iodine permeation suppressing layer are very thin, and the adhesive layer or adhesive layer for laminating the iodine permeation suppressing layer can be omitted. The total thickness of the polarizing plate can be made extremely thin. Furthermore, such an iodine permeation suppressing layer has the advantage of being excellent in humidification durability because it has lower moisture absorption and moisture permeability than a solidified product of an aqueous coating film such as an aqueous solution or aqueous dispersion. As a result, it is possible to realize a highly durable polarizing plate that can maintain its optical properties even in a high-temperature and high-humidity environment. Moreover, such an iodine permeation suppressing layer can suppress adverse effects on a polarizing plate (polarizer) due to ultraviolet irradiation, compared to, for example, a cured product of an ultraviolet curable resin. The iodine permeation suppressing layer is preferably a solidified coating film of a resin solution in an organic solvent. The solidified product shrinks less during film formation than the cured product, and since it does not contain residual monomers, etc., deterioration of the film itself is suppressed. Adverse effects can be suppressed.

Further, the glass transition temperature (Tg) of the resin constituting the iodine permeation suppressing layer is, for example, 85° C. or higher, and the weight average molecular weight Mw is, for example, 25,000 or higher. If the Tg and Mw of the resin are in such ranges, the synergistic effect with the effect of forming the iodine permeation suppressing layer from the solidified or thermoset coating film of the organic solvent solution of the resin is very high. Despite being extremely thin, migration of iodine in the polarizer to the pressure-sensitive adhesive layer (finally, the image display cell) can be remarkably suppressed. As a result, excellent durability under high temperature and high humidity environment can be achieved. The Tg of the resin is preferably 90° C. or higher, more preferably 100° C. or higher, still more preferably 110° C. or higher, and particularly preferably 120° C. or higher. The upper limit of Tg can be, for example, 200°C. Also, the Mw of the resin is preferably 30,000 or more, more preferably 35,000 or more, and still more preferably 40,000 or more. The upper limit of Mw can be 150,000, for example.

As the resin constituting the iodine permeation suppression layer, any appropriate thermoplastic resin can be used as long as it can form a solidified product or a thermoset product of a coating film of an organic solvent solution and has the Tg and Mw as described above. Alternatively, a thermosetting resin can be used. Thermoplastic resins are preferred. Examples of thermoplastic resins include acrylic resins and epoxy resins. An acrylic resin and an epoxy resin may be used in combination. Representative examples of acrylic resins and epoxy resins that can be used in the iodine permeation suppressing layer are described below.

Acrylic resins typically contain, as a main component, repeating units derived from (meth)acrylic acid ester monomers having a linear or branched structure. As used herein, (meth)acryl refers to acryl and/or methacryl. The acrylic resin may contain repeating units derived from any appropriate comonomers depending on the purpose. Examples of copolymerizable monomers (copolymerizable monomers) include carboxyl group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, aromatic ring-containing (meth)acrylates, and heterocyclic ring-containing vinyl monomers. By appropriately setting the type, number, combination and copolymerization ratio of the monomer units, an acrylic resin having the predetermined Mw can be obtained.

（式中、Ｘはビニル基、（メタ）アクリル基、スチリル基、（メタ）アクリルアミド基、ビニルエーテル基、エポキシ基、オキセタン基、ヒドロキシル基、アミノ基、アルデヒド基、および、カルボキシル基からなる群より選択される少なくとも１種の反応性基を含む官能基を表し、Ｒ^１およびＲ^２はそれぞれ独立して、水素原子、置換基を有していてもよい脂肪族炭化水素基、置換基を有していてもよいアリール基、または、置換基を有していてもよいヘテロ環基を表し、Ｒ^１およびＲ^２は互いに連結して環を形成してもよい）。 <Boron-containing acrylic resin>
In one embodiment, the acrylic resin is more than 50 parts by weight of a (meth)acrylic monomer and more than 0 parts by weight and less than 50 parts by weight of the monomer represented by formula (1) (hereinafter , may be referred to as a copolymer monomer) and a copolymer obtained by polymerizing a monomer mixture (hereinafter sometimes referred to as a boron-containing acrylic resin) including:

(Wherein, X is a vinyl group, a (meth)acryl group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetane group, a hydroxyl group, an amino group, an aldehyde group, and a group consisting of a carboxyl group Represents a selected functional group containing at least one reactive group, and R ¹ and R ² each independently represent a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, or a substituted or an optionally substituted heterocyclic group, and R ¹ and R ² may be linked together to form a ring).

（式中、Ｒ^６は任意の官能基を表し、jおよびｋは１以上の整数を表す）。 A boron-containing acrylic resin typically has a repeating unit represented by the following formula. By polymerizing a monomer mixture containing a copolymerizable monomer represented by formula (1) and a (meth)acrylic monomer, the boron-containing acrylic resin has a substituent containing boron in the side chain (e.g., repeating unit k in the following formula). Thereby, when the iodine permeation suppressing layer is arranged adjacent to the polarizer, the adhesion to the polarizer can be improved. The boron-containing substituent may be included continuously (that is, in blocks) in the boron-containing acrylic resin, or may be included randomly.

(Wherein, ^R6 represents an arbitrary functional group, and j and k represent integers of 1 or more).

<(Meth) acrylic monomer>
Any appropriate (meth)acrylic monomer can be used as the (meth)acrylic monomer. Examples thereof include (meth)acrylic acid ester-based monomers having a linear or branched structure and (meth)acrylic acid ester-based monomers having a cyclic structure.

Examples of (meth)acrylic ester-based monomers having a linear or branched structure include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, and (meth)acrylic acid. isopropyl, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, methyl 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate and the like. . Preferably, methyl (meth)acrylate is used. The (meth)acrylic acid ester-based monomers may be used alone or in combination of two or more.

Examples of (meth)acrylic ester-based monomers having a cyclic structure include cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, ( meth)dicyclopentenyl acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, biphenyl (meth)acrylate, o-biphenyloxyethyl (meth)acrylate, o-biphenyloxyethoxy Ethyl (meth)acrylate, m-biphenyloxyethyl acrylate, p-biphenyloxyethyl (meth)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, biphenyl group-containing monomers such as o-phenylphenol glycidyl ether acrylate, terphenyl (meth)acrylate, o-terphenyloxyethyl (meth)acrylate and the like. Preferably, 1-adamantyl (meth)acrylate and dicyclopentanyl (meth)acrylate are used. A polymer having a high glass transition temperature can be obtained by using these monomers. These monomers may be used alone or in combination of two or more.

A silsesquioxane compound having a (meth)acryloyl group may be used instead of the (meth)acrylic acid ester-based monomer. By using a silsesquioxane compound, an acrylic polymer having a high glass transition temperature can be obtained. Silsesquioxane compounds are known to have various skeleton structures, such as cage structures, ladder structures, and random structures. The silsesquioxane compound may have only one of these structures, or may have two or more. Silsesquioxane compounds may be used alone or in combination of two or more.

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

The (meth)acrylic monomer is used in an amount exceeding 50 parts by weight with respect to 100 parts by weight of the monomer mixture.

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

As the aliphatic hydrocarbon group in the above formula (1), a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, 3 to 3 carbon atoms which may have a substituent 20 cyclic alkyl groups and alkenyl groups having 2 to 20 carbon atoms. Examples of the aryl group include an optionally substituted phenyl group having 6 to 20 carbon atoms and a naphthyl group having 10 to 20 carbon atoms which may have a substituent. The heterocyclic group includes a 5- or 6-membered ring group containing at least one optionally substituted heteroatom. R ¹ and R ² may be linked together to form a ring. R ¹ and R ² are preferably a hydrogen atom or a linear or branched alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom.

Reactive groups contained in the functional group represented by X include vinyl group, (meth)acryl group, styryl group, (meth)acrylamide group, vinyl ether group, epoxy group, oxetane group, hydroxyl group, amino group, aldehyde group, and at least one selected from the group consisting of carboxyl groups. Preferably, the reactive groups are (meth)acryl and/or (meth)acrylamide groups. By having these reactive groups, the adhesion to the polarizer can be further improved when the iodine permeation suppressing layer is arranged adjacent to the polarizer.

In one embodiment, the functional group represented by X is preferably a functional group represented by ZY-. Here, Z is selected from the group consisting of a vinyl group, a (meth)acryl group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetane group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group. and Y represents a phenylene group or an alkylene group.

Specifically, the following compounds can be used as the comonomer.

The comonomer is used in a content of more than 0 parts by weight and less than 50 parts by weight with respect to 100 parts by weight of the monomer mixture. It is preferably 0.01 to 50 parts by weight, more preferably 0.05 to 20 parts by weight, even more preferably 0.1 to 10 parts by weight, and particularly preferably 0.1 part by weight to 10 parts by weight. 5 to 5 parts by weight.

<Acrylic resin containing lactone ring, etc.>

In another embodiment, the acrylic resin has a repeating unit containing a ring structure selected from lactone ring units, glutaric anhydride units, glutarimide units, maleic anhydride units and maleimide (N-substituted maleimide) units. . As for the repeating unit containing a ring structure, only one type may be included in the repeating unit of the acrylic resin, or two or more types may be included.

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

一般式（２）において、Ｒ^２、Ｒ^３およびＲ^４は、それぞれ独立して、水素原子または炭素数１～２０の有機残基を表す。なお、有機残基は酸素原子を含んでいてもよい。アクリル系樹脂には、単一のラクトン環単位のみが含まれていてもよく、上記一般式（２）におけるＲ^２、Ｒ^３およびＲ^４が異なる複数のラクトン環単位が含まれていてもよい。ラクトン環単位を有するアクリル系樹脂は、例えば特開２００８－１８１０７８号公報に記載されており、当該公報の記載は本明細書に参考として援用される。

In 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, for example, in JP-A-2008-181078, and the description of the publication is incorporated herein by reference.

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

In general formula (3), R ¹¹ and R ¹² each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms; R ¹³ is an alkyl group having 1 to 18 carbon atoms; or an aryl group having 6 to 10 carbon atoms. In general formula (3), preferably R ¹¹ and R ¹² are each independently hydrogen or methyl, and R ¹³ is hydrogen, methyl, butyl or cyclohexyl. More preferably, R ¹¹ is a methyl group, R ¹² is hydrogen and R ¹³ is a methyl group. The acrylic resin may contain only a single glutarimide unit, or may contain a plurality of glutarimide units in which R ¹¹ , R ¹² and R ¹³ in the general formula (3) are different. . Acrylic resins having a glutarimide unit, for example, JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328334, JP-A-2006-337491, JP-A-2006-337492 JP-A-2006-337493 and JP-A-2006-337569, and the descriptions in these publications are incorporated herein by reference. As for the glutaric anhydride unit, the above explanation regarding the glutarimide unit applies, except that the nitrogen atom substituted by R ¹³ in the general formula (3) becomes an oxygen atom.

As for the maleic anhydride unit and the maleimide (N-substituted maleimide) unit, their structures are specified by their names, so detailed descriptions thereof are omitted.

The content of repeating units containing a ring structure in the acrylic resin is preferably 1 mol % to 50 mol %, more preferably 10 mol % to 40 mol %, still more preferably 20 mol % to 30 mol %. In addition, acrylic resin contains the repeating unit derived from said (meth)acrylic-type monomer as a main repeating unit.

<Epoxy resin>
As the epoxy resin, an epoxy resin having an aromatic ring is preferably used. Adhesion between the iodine permeation suppressing layer and the polarizer can be improved by using an epoxy resin having an aromatic ring as the epoxy resin. Furthermore, when the pressure-sensitive adhesive layer is arranged adjacent to the iodine permeation suppressing layer, the anchoring force of the pressure-sensitive adhesive layer can be improved. Examples of epoxy resins having an aromatic ring include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin; phenol novolak epoxy resin, cresol novolak epoxy resin, hydroxybenzaldehyde phenol novolak Novolac type epoxy resins such as epoxy resins; polyfunctional epoxy resins such as glycidyl ether of tetrahydroxyphenylmethane, glycidyl ether of tetrahydroxybenzophenone, epoxidized polyvinylphenol, naphthol type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin and the like. Bisphenol A type epoxy resin, biphenyl type epoxy resin, and bisphenol F type epoxy resin are preferably used. Epoxy resins may be used alone or in combination of two or more.

The iodine permeation suppressing layer can be formed by applying an organic solvent solution of the resin as described above to form a coating film, and solidifying or thermally curing the coating film. Any appropriate organic solvent that can dissolve or uniformly disperse the acrylic resin can be used as the organic solvent. Specific examples of organic solvents include ethyl acetate, toluene, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone. The resin concentration of the solution is preferably 3 to 20 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film can be formed.

The solution may be applied to any suitable substrate and may be applied to the polarizer. When the solution is applied to the substrate, the solidified coating film (iodine permeation suppressing layer) formed on the substrate is transferred to the polarizer. When the solution is applied to the polarizer, the protective layer is directly formed on the polarizer by drying (solidifying) the applied film. Preferably, the solution is applied to the polarizer to form a protective layer directly on the polarizer. With such a configuration, the adhesive layer or pressure-sensitive adhesive layer required for transfer can be omitted, so the polarizing plate can be made even thinner. Any appropriate method can be adopted as a method of applying the solution. Specific examples include roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, and knife coating (comma coating, etc.).

The iodine permeation suppression layer can be formed by solidifying or thermally curing the coating film of the solution. The heating temperature for solidification or heat curing is preferably 100°C or less, more preferably 50°C to 70°C. If the heating temperature is within this range, it is possible to prevent adverse effects on the polarizer. The heating time can vary depending on the heating temperature. The heating time can be, for example, 1 minute to 10 minutes.

The iodine permeation suppressing layer (substantially an organic solvent solution of the above resin) may contain any appropriate additive depending on the purpose. Specific examples of additives include ultraviolet absorbers; leveling agents; antioxidants such as hindered phenol, phosphorus, and sulfur; stabilizers such as light stabilizers, weather stabilizers, and heat stabilizers; Reinforcing materials such as carbon fiber; near-infrared absorbers; flame retardants such as tris(dibromopropyl) phosphate, triallyl phosphate, and antimony oxide; antistatic agents such as anionic, cationic, and nonionic surfactants; inorganic pigments , organic pigments, colorants such as dyes; organic fillers or inorganic fillers; resin modifiers; organic fillers or inorganic fillers; plasticizers; The type, number, combination, addition amount, etc. of additives can be appropriately set according to the purpose.

The iodine permeation suppression layer has, for example, an iodine absorption index of 0.015 or less. The iodine absorption index is preferably 0.012 or less, more preferably 0.009 or less, still more preferably 0.007 or less, and particularly preferably 0.005 or less. The smaller the iodine absorption index, the better. The iodine absorption index is an index of the iodine permeation suppressing ability of the iodine permeation suppressing layer, and the smaller the index, the more difficult it is for iodine to be absorbed by the iodine permeation suppressing layer (that is, the easier it is for iodine to be blocked by the iodine permeation suppressing layer). show. Therefore, if the iodine absorption index is in such a range, the iodine existence index of the adhesive layer can be set to 0.050 or less as described above, and iodine in the polarizer is absorbed into the adhesive layer (eventually An image display device (substantially an image display cell) can be remarkably suppressed. As a result, the thin polarizing plate can achieve excellent durability in a high-temperature and high-humidity environment. Furthermore, when the polarizing plate is applied to an image display device, corrosion of metal members (e.g., electrodes, sensors, wiring, metal layers) of the image display device can be significantly suppressed, and in a high-temperature and high-humidity environment Therefore, it is possible to suppress the decrease in reliability due to iodine, and thus suppress the increase in reflectance. Furthermore, as described above, the iodine permeation suppressing layer preferably has a potassium absorption index of 0.015 or less. The potassium absorption index is more preferably 0.013 or less, still more preferably 0.011 or less, and particularly preferably 0.009 or less. The lower the potassium absorption index, the better, ideally it is zero, and its lower limit can be, for example, 0.002. The potassium absorption index is an index of the ability of the iodine permeation suppressing layer to suppress potassium permeation. The smaller this index is, the less potassium is absorbed by the iodine permeation suppressing layer. This indicates that iodine in the form of I ₃ ⁻ K ⁺ ) is difficult to be absorbed by the iodine permeation suppressing layer. Therefore, if the potassium absorption index is within such a range, the transfer of iodine can be suppressed not only in the form of simple iodine but also in the form of potassium iodide and potassium polyiodide. The iodine absorption index can be defined as the iodine intensity (kcps) obtained by the fluorescent X-ray analysis of the iodine permeation suppressing layer, and the potassium absorption index as the potassium intensity (kcps) obtained by the fluorescent X-ray analysis of the iodine permeation suppressing layer. can be defined.

B. Polarizing plate with retardation layer B-1. Overall Configuration of Polarizing Plate with Retardation Layer A polarizing plate with a retardation layer according to an embodiment of the present invention has a polarizing plate and a retardation layer. The polarizing plate is the polarizing plate described in item A above. In an embodiment of the invention, the retardation layer is arranged between the polarizer and the adhesive layer. The retardation layer is an alignment fixed layer of a liquid crystal compound having a circularly polarized light function or an elliptically polarized light function (hereinafter sometimes simply referred to as a liquid crystal alignment fixed layer). FIG. 2A is a schematic cross-sectional view of a polarizing plate with a retardation layer according to one embodiment of the invention; FIG. 2B is a schematic cross-sectional view of a polarizing plate with a retardation layer according to another embodiment of the invention. 2A and 2B each have a protective layer 12, a polarizer 11, a retardation layer 20, and an adhesive layer 30 in this order from the viewing side. In the embodiment of the invention, the iodine permeation suppression layer 40 is provided between the polarizer 11 and the adhesive layer 30 . By providing an iodine permeation suppression layer in the polarizing plate with a retardation layer, as described above with respect to the polarizing plate, iodine in the polarizer is added to the adhesive layer (eventually the image display device, substantially the image display cell). Migration can be remarkably suppressed. As a result, it is possible to realize excellent durability in a thin polarizing plate with a retardation layer in a high-temperature and high-humidity environment. Furthermore, when the polarizing plate with a retardation layer is applied to an image display device, corrosion of metal members (e.g., electrodes, sensors, wiring, metal layers) of the image display device can be significantly suppressed, and high-temperature It is possible to suppress an increase in reflectance in a high-humidity environment. The iodine permeation suppression layer 40 may be provided between the polarizer 11 and the retardation layer 20 (that is, adjacent to the polarizer 11) as shown in FIG. It may be provided between the layer 20 and the adhesive layer 30 . When the iodine permeation suppression layer is provided between the polarizer and the retardation layer (especially when the iodine permeation suppression layer is adjacent to the polarizer), iodine transfer from the polarizer can be suppressed in a high temperature and high humidity environment. This has the advantage of improving reliability. When the iodine permeation suppression layer is provided between the retardation layer and the adhesive layer (especially when the iodine permeation suppression layer is adjacent to the adhesive layer), components other than iodine that are considered to affect metal corrosion (e.g. , residual monomer components in the UV-curable adhesive, decomposition products of the photoinitiator) can also be prevented from migrating into the adhesive at the same time, and there is the advantage that the metal corrosion inhibitory effect is further enhanced.

As shown in FIG. 3, in a retardation layer-attached polarizing plate 102 according to yet another embodiment, another retardation layer 50 and/or a conductive layer or an isotropic substrate 60 with a conductive layer may be provided. Another retardation layer 50 is typically provided between the retardation layer 20 and the adhesive layer 30 (that is, outside the retardation layer 20). Another retardation layer typically exhibits a refractive index characteristic of nz>nx=ny. The conductive layer or isotropic base material 60 with a conductive layer is typically provided between the iodine permeation suppressing layer 40 and the adhesive layer 30 (that is, outside the iodine permeation suppressing layer 40). Another retardation layer 50 and a conductive layer or an isotropic substrate 60 with a conductive layer are typically provided in this order from the retardation layer 20 side. In the illustrated example, the iodine permeation suppressing layer 40, the retardation layer 20, another retardation layer 50, and the conductive layer or the isotropic substrate with the conductive layer 60 are provided in this order from the viewing side. As long as the layer 50 is provided between the retardation layer 20 and the adhesive layer 30, and the conductive layer or the isotropic substrate with a conductive layer 60 is provided between the iodine permeation suppressing layer 40 and the adhesive layer 30, any Any suitable placement order may be employed. The separate retardation layer 50 and the conductive layer or the isotropic substrate with a conductive layer 60 are typically optional layers provided as needed, and either or both of them may be omitted. For the sake of convenience, the retardation layer 20 may be referred to as a first retardation layer, and the other retardation layer 50 may be referred to as a second retardation layer. When a conductive layer or an isotropic substrate with a conductive layer is provided, the polarizing plate with a retardation layer is a so-called inner touch panel type in which a touch sensor is incorporated between the image display cell (e.g., organic EL cell) and the polarizing plate. It can be applied to input display devices. In the embodiment of the present invention, by providing the conductive layer or the isotropic base material 60 with the conductive layer outside the iodine permeation suppression layer 40, corrosion of the conductive layer can be significantly suppressed.

As described above, the first retardation layer 20 is a liquid crystal alignment fixed layer. The first retardation layer 20 can be a single layer as shown in FIGS. 22 may have a laminated structure.

The above-described embodiments may be combined as appropriate, and the constituent elements in the above-described embodiments may be modified as is obvious in the art. For example, the retardation layer-attached polarizing plate 101 of FIG. 2B may be provided with the second retardation layer 50 and/or the conductive layer or the conductive layer-attached isotropic substrate 60; The retardation layer 20 may have a two-layer structure as shown in FIG. 4; the retardation layer-attached polarizing plate 103 in FIG. A tropic substrate 60 may be provided; the iodine permeation suppression layer 40 of the polarizing plate 102 with a retardation layer in FIG. good.

The retardation layer-attached polarizing plate according to the embodiment of the present invention may further include other retardation layers. Other optical properties of the retardation layer (for example, refractive index properties, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, etc. can be appropriately set according to the purpose.

The total thickness of the retardation layer-attached polarizing plate is preferably 60 μm or less, more preferably 55 μm or less, still more preferably 50 μm or less, and particularly preferably 40 μm or less. A lower limit for the total thickness can be, for example, 28 μm. According to the embodiment of the present invention, it is possible to realize such an extremely thin polarizing plate with a retardation layer, and furthermore, such an extremely thin polarizing plate with a retardation layer has excellent durability in a high-temperature and high-humidity environment. It is possible to realize sexuality. Furthermore, even when such a very thin retardation layer-attached polarizing plate is applied to an image display device, corrosion of metal members (e.g., electrodes, sensors, wiring, metal layers) of the image display device is noticeable. In addition, it is possible to suppress an increase in reflectance under a high-temperature and high-humidity environment. The total thickness of the polarizing plate with a retardation layer refers to the polarizing plate, the retardation layer (the first retardation layer and the second retardation layer if present), the iodine permeation suppression layer, and the lamination of these The total thickness of the adhesive layer or pressure-sensitive adhesive layer for (that is, the total thickness of the polarizing plate with a retardation layer is the conductive layer or the isotropic substrate 60 with the conductive layer, and the pressure-sensitive adhesive layer 30 and its surface. It does not include the thickness of the release film that can be temporarily attached).

Among the descriptions of the above section A regarding the configuration, effects and uses of the polarizing plate, those that are applicable to the polarizing plate with the retardation layer can be used as the description regarding the polarizing plate with the retardation layer. For example, the shape of the polarizing plate (leaf-shaped or elongated) and thinning, the image display device to which the polarizing plate can be applied, the release film, and the description on the direct formation of the iodine permeation suppression layer on the polarizer, the retardation It can be used as a description of the layered polarizing plate. Of course, these are examples, and the description that can be incorporated is not limited to these. Similarly, the later-described descriptions of the configuration, effects, and uses of the retardation layer-attached polarizing plate that can be applied to the polarizing plate can be used as the description of the polarizing plate.

Hereinafter, the first retardation layer, the second retardation layer, and the conductive layer or the isotropic substrate with the conductive layer, which are constituent elements of the polarizing plate with the retardation layer, will be described. The polarizer, the protective layer, and the iodine permeation suppressing layer are as described in section A above.

B-2. First Retardation Layer The first retardation layer 20 is a liquid crystal alignment fixed layer as described above. By using a liquid crystal compound, the difference between nx and ny in the resulting retardation layer can be significantly increased compared to a non-liquid crystal material. can be significantly reduced. As a result, it is possible to further reduce the thickness of the retardation layer-attached polarizing plate. As used herein, the term “liquid crystal alignment fixed layer” refers to a layer in which a liquid crystal compound is aligned in a predetermined direction within the layer and the alignment state is fixed. In addition, the "alignment fixed layer" is a concept including an alignment cured layer obtained by curing a liquid crystal monomer as described later. In the present embodiment, typically, rod-shaped liquid crystal compounds are aligned in the slow axis direction of the first retardation layer (homogeneous alignment).

Examples of liquid crystal compounds include liquid crystal compounds whose liquid crystal phase is a nematic phase (nematic liquid crystal). As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. Either lyotropic or thermotropic mechanism may be used to develop the liquid crystallinity of the liquid crystal compound. The liquid crystal polymer and liquid crystal monomer 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 crosslinkable monomer. This is because the alignment state of the liquid crystal monomer can be fixed by polymerizing or cross-linking (that is, curing) the liquid crystal monomer. After aligning the liquid crystal monomers, for example, the alignment state can be fixed by polymerizing or cross-linking the liquid crystal monomers. Here, a polymer is formed by polymerization and a three-dimensional network structure is formed by cross-linking, but these are non-liquid crystalline. Therefore, the formed first retardation layer does not undergo a transition to a liquid crystal phase, a glass phase, or a crystal phase due to a change in temperature, which is peculiar to liquid crystalline compounds. As a result, the first retardation layer becomes a highly stable retardation layer that is not affected by temperature changes.

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

Any appropriate liquid crystal monomer can be employed as the liquid crystal monomer. For example, polymerizable mesopolymers described in JP-T-2002-533742 (WO00/37585), EP358208 (US5211877), EP66137 (US4388453), WO93/22397, EP0261712, DE19504224, DE4408171, and GB2280445 Gen compounds and the like can be used. Specific examples of such polymerizable mesogenic compounds include LC242 (trade name) available from BASF, E7 (trade name) available from Merck, and LC-Sillicon-CC3767 (trade name) available from Wacker-Chem. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable.

The liquid crystal alignment fixed layer is obtained by subjecting the surface of a predetermined base material to alignment treatment, coating the surface with a coating liquid containing a liquid crystal compound, and orienting the liquid crystal compound in the direction corresponding to the alignment treatment, and It can be formed by fixing the state. In one embodiment, the base material is any suitable resin film, and the liquid crystal alignment fixed layer formed on the base material is transferred to the surface of the adjacent layer (e.g., polarizer, iodine permeation suppression layer). can be

Any appropriate alignment treatment may be adopted as the alignment treatment. Specific examples include mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment. Specific examples of mechanical orientation treatment include rubbing treatment and stretching treatment. Specific examples of physical orientation treatment include magnetic orientation treatment and electric field orientation treatment. Specific examples of chemical alignment treatment include oblique vapor deposition and photo-alignment treatment. Arbitrary appropriate conditions can be adopted as the processing conditions for various alignment treatments depending on the purpose.

Alignment of the liquid crystal compound is performed by treatment at a temperature at which a liquid crystal phase is exhibited depending on the type of liquid crystal compound. By performing such a temperature treatment, the liquid crystal compound assumes a liquid crystal state, and the liquid crystal compound is aligned in accordance with the orientation treatment direction of the surface of the base material.

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

Specific examples of the liquid crystal compound and details of the method for forming the alignment fixed layer are described in JP-A-2006-163343. The description of the publication is incorporated herein by reference.

In one embodiment, the first retardation layer 20 is a single layer as shown in FIGS. 2A, 2B and 3. FIG. When the first retardation layer 20 is composed of a single layer, its thickness is preferably 0.5 μm to 7 μm, more preferably 1 μm to 5 μm. By using a liquid crystal compound, it is possible to realize an in-plane retardation equivalent to that of a resin film with a thickness much thinner than that of a resin film.

The first retardation layer has a circularly polarizing function or an elliptically polarizing function as described above. The first retardation layer typically exhibits a refractive index characteristic of nx>ny=nz. The first retardation layer is typically provided to impart antireflection properties to the polarizing plate, and can function as a λ/4 plate when the first retardation layer is a single layer. In this case, the in-plane retardation Re(550) of the first retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, still more preferably 130 nm to 160 nm. Here, "ny=nz" includes not only the case where ny and nz are completely equal but also the case where they are substantially equal. Therefore, ny>nz or ny<nz may be satisfied within a range that does not impair the effects of the present invention.

The Nz coefficient of the first retardation layer is preferably 0.9-1.5, more preferably 0.9-1.3. By satisfying such a relationship, when the obtained polarizing plate with a retardation layer is used in an image display device, a very excellent reflection hue can be achieved.

The first retardation layer may exhibit a reverse wavelength dispersion characteristic in which the retardation value increases according to the wavelength of the measurement light, or has a positive wavelength dispersion characteristic in which the retardation value decreases according to the wavelength of the measurement light. It may also show a flat wavelength dispersion characteristic in which the phase difference value hardly changes even with the wavelength of the measurement light. In one embodiment, the first retardation layer exhibits reverse dispersion wavelength characteristics. In this case, Re(450)/Re(550) of the retardation layer is preferably 0.8 or more and less than 1, more preferably 0.8 or more and 0.95 or less. With such a configuration, very excellent antireflection properties can be achieved.

The angle θ between the slow axis of the first retardation layer 20 and the absorption axis of the polarizer 11 is preferably 40° to 50°, more preferably 42° to 48°, and more preferably about 45°. If the angle θ is in such a range, by using the λ / 4 plate as the first retardation layer as described above, very good circular polarization properties (as a result, very good antireflection properties) can be obtained.

In another embodiment, the first retardation layer 20 may have a laminated structure of a first liquid crystal alignment fixed layer 21 and a second liquid crystal alignment fixed layer 22 as shown in FIG. In this case, one of the first liquid crystal alignment fixed layer 21 and the second liquid crystal alignment fixed layer 22 can function as a λ/4 plate, and the other can function as a λ/2 plate. Therefore, the thicknesses of the first liquid crystal alignment fixed layer 21 and the second liquid crystal alignment fixed layer 22 can be adjusted so as to obtain the desired in-plane retardation of the λ/4 plate or λ/2 plate. For example, when the first liquid crystal alignment fixed layer 21 functions as a λ/2 plate and the second liquid crystal alignment fixed layer 22 functions as a λ/4 plate, the thickness of the first liquid crystal alignment fixed layer 21 is, for example, 2 0 μm to 3.0 μm, and the thickness of the second liquid crystal alignment fixing layer 22 is, for example, 1.0 μm to 2.0 μm. In this case, the in-plane retardation Re(550) of the first liquid crystal alignment fixed layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, still more preferably 250 nm to 280 nm. The in-plane retardation Re(550) of the second liquid crystal alignment fixed layer is as described above for the single layer. The angle formed by the slow axis of the first liquid crystal alignment fixed layer and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and still more preferably about 15°. is. The angle formed by the slow axis of the second liquid crystal alignment fixed layer and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, and more preferably about 75°. is. With such a configuration, it is possible to obtain characteristics close to ideal reverse wavelength dispersion characteristics, and as a result, very excellent antireflection characteristics can be realized. The liquid crystal compounds constituting the first liquid crystal alignment fixed layer and the second liquid crystal alignment fixed layer, the method of forming the first liquid crystal alignment fixed layer and the second liquid crystal alignment fixed layer, the optical characteristics, etc. are described above for the single layer. As explained in

B-3. Second Retardation Layer As described above, the second retardation layer can be a so-called positive C plate whose refractive index characteristics exhibit a relationship of nz>nx=ny. By using a positive C plate as the second retardation layer, it is possible to satisfactorily prevent reflection in oblique directions and widen the viewing angle of the antireflection function. In this case, the thickness direction retardation Rth (550) of the second retardation layer is preferably −50 nm to −300 nm, more preferably −70 nm to −250 nm, still more preferably −90 nm to −200 nm, particularly preferably -100 nm to -180 nm. Here, "nx=ny" includes not only the case where nx and ny are strictly equal but also the case where nx and ny are substantially equal. That is, the in-plane retardation Re(550) of the second retardation layer can be less than 10 nm.

The second retardation layer having a refractive index characteristic of nz>nx=ny can be made of any suitable material. The second retardation layer preferably consists of a film containing a liquid crystal material fixed in homeotropic alignment. A liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the retardation layer include the liquid crystal compound and the method for forming the retardation layer described in [0020] to [0028] of JP-A-2002-333642. In this case, the thickness of the second retardation layer is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, still more preferably 0.5 μm to 5 μm.

B-4. Conductive layer or isotropic substrate with conductive layer It may be formed by depositing a metal oxide film thereon. Examples of metal oxides include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. Among them, indium-tin composite oxide (ITO) is preferred.

When the conductive layer contains 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 is transferred from the base material to the first retardation layer (or the iodine permeation suppression layer or the second retardation layer if present), and the conductive layer alone constitutes a polarizing plate with a retardation layer. It may be a layer, and the first retardation layer (or the iodine permeation suppressing layer or the second retardation layer if present) as a laminate with the substrate (substrate with conductive layer). may Preferably, the substrate is optically isotropic, and therefore the conductive layer can be used as an isotropic substrate with a conductive layer in a polarizing plate with a retardation layer.

Any appropriate isotropic substrate can be employed as the optically isotropic substrate (isotropic substrate). Materials constituting the isotropic base material include, for example, norbornene-based resins, olefin-based resins, and other resins that do not have a conjugated system as the main skeleton, and acrylic resins that have cyclic structures such as lactone rings and glutarimide rings. Examples include materials that are present in the main chain. By using such a material, it is possible to suppress the development of retardation due to the orientation of molecular chains when forming an isotropic base material. The thickness of the isotropic substrate is preferably 50 μm or less, more preferably 35 μm or less. The lower limit of the thickness of the isotropic base material is, for example, 20 μm.

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

C. Image Display Device The polarizing plate described in item A above and the polarizing plate with a retardation layer described in item B above can be applied to an image display device. Accordingly, embodiments of the present invention include image display devices using such polarizing plates or polarizing plates with retardation layers. Typical examples of image display devices include liquid crystal display devices and electroluminescence (EL) display devices (eg, organic EL display devices and inorganic EL display devices). The image display device according to the embodiment of the present invention typically includes the polarizing plate described in item A or the polarizing plate with a retardation layer described in item B on the viewing side thereof. The retardation layer-attached polarizing plate is laminated so that the retardation layer is on the image display cell (for example, liquid crystal cell, organic EL cell, inorganic EL cell) side (so that the polarizer is on the viewing side). Although such an image display device is very thin, corrosion of metal members is remarkably suppressed. In one embodiment, the image display device has a curved shape (substantially a curved display screen) and/or is foldable or foldable. In addition, the polarizing plate described in the above item A may be arranged on the back side of the image display device depending on the purpose.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. The measurement method of each characteristic is as follows. "Parts" and "%" in Examples and Comparative Examples are by weight unless otherwise specified.

(1) Thickness A thickness of 10 μm or less was measured using an interferometric film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name “MCPD-3000”). A thickness exceeding 10 μm was measured using a digital micrometer (manufactured by Anritsu Co., Ltd., product name “KC-351C”).

(2) Iodine existence index The retardation layer-equipped polarizing plates or polarizing plates obtained in Examples and Comparative Examples were bonded to alkali-free glass to prepare test samples. After subjecting this test sample to a reliability test (placed in an environment of 85 ° C. / 85% RH for 240 hours and then left in an environment of 23 ° C. / 55% RH for 24 hours), the alkali-free glass was cut using a trimming knife. was peeled off together with the adhesive. Secondary ion mass spectrometry (TOF-SIMS) was performed on the adhesive surface of the peeled test sample using "TOFSIMS5" manufactured by IONTOF. The measurement conditions were as follows.
Irradiated primary ions: Bi ₃ ²⁺
・Primary ion acceleration voltage: 25 kV
・Measurement area: 100 μm ²
・Measurement polarity: negative ions Among the obtained negative secondary ions, the ionic strength of C ₃ H ₃ O ₂ ⁻ (m/z=71) derived from acrylic (adhesive) and I ⁻ derived from iodine (m/z = 127) was extracted, and the iodine abundance index was calculated using the following formula.
Iodine abundance index = I ^- ionic strength/C ₃ H ₃ O ₂ ^- ionic strength

(3) Iodine absorption index and potassium absorption index The resin solution used in Examples and Comparative Examples was applied to a polyethylene terephthalate (PET) film of 38 μm so that the thickness after drying was 1 μm, and dried to form a resin layer/ A test sample of PET film was obtained. The obtained test sample was immersed in a 10% potassium iodide aqueous solution (90 parts by weight of pure water, 10 parts by weight of potassium iodide) adjusted to 23° C. for 24 hours. After the immersion, the test sample was taken out from the aqueous solution, water droplets on the surface were wiped off, and the intensity (kcps) of iodine and potassium was obtained by fluorescent X-ray measurement of the surface of the resin layer. The strength of iodine obtained was defined as the iodine absorption index, and the strength of potassium was defined as the potassium absorption index. The conditions for the fluorescent X-ray analysis were as follows.
・ Analysis device: X-ray fluorescence spectrometer (XRF) manufactured by Rigaku Denki Kogyo Co., Ltd., product name “ZSX100e”
・Test sample: circular sample with a diameter of 10 mm ・Anticathode: rhodium ・Analyzing crystal: lithium fluoride ・Excitation light energy: 40 kV-90 mA
・ Iodine measurement line: I-LA
・ Quantification method: FP method ・ 2θ angle peak: 103.078 deg (iodine), 136.847 deg (potassium)
・Measurement time: 40 seconds

(4) Change in Degree of Polarization The retardation layer-equipped polarizing plates or polarizing plates obtained in Examples and Comparative Examples were bonded to alkali-free glass to prepare test samples. The degree of polarization of this test sample was measured by a standard method, and this was taken as the initial degree of polarization. Furthermore, after subjecting the test sample to a reliability test (placed in an environment of 85 ° C. / 85% RH for 240 hours, then left in an environment of 23 ° C. / 55% RH for 24 hours), the degree of polarization was obtained in the same manner as above. was measured. The polarization degree change was calculated by the following formula.
Change in degree of polarization (%) = initial degree of polarization (%) - degree of polarization after reliability test (%)
Furthermore, evaluation was made according to the following criteria.
Good: Change in degree of polarization is less than 5.0% Poor: Change in degree of polarization is 5.0% or more

(5) Increase in Reflectance The polarizing plates with retardation layers obtained in Examples and Comparative Examples were bonded to alkali-free glass to prepare test samples. This test sample is placed on a reflector with a reflectance of 80%, and a spectrophotometer (Konica Minolta CM700D) is used to measure the reflectance (%) at 550 nm in SCI mode. rate. Furthermore, after subjecting the test sample to a reliability test (placed in an environment of 60 ° C. and 90% RH for 500 hours, then left in an environment of 23 ° C. and 55% RH for 24 hours), the reflectance was measured in the same manner as above. was measured. The increase in reflectance was calculated by the following formula.
Reflectance increase (%) = initial reflectance (%) - reflectance after reliability test (%)
Furthermore, evaluation was made according to the following criteria.
Good: Increase in reflectance is less than 0.50% Acceptable: Increase in reflectance is 0.50% or more and less than 1.00% Poor: Increase in reflectance is 1.00% or more

(6) Metal corrosiveness (48 hours)
A silver nanowire solution (manufactured by MERCK, nanowire size: diameter 115 nm, length 20 μm to 50 μm, solid content 0.5% isopropyl alcohol (IPA) solution) is applied to one side of a 50 μm polyethylene terephthalate (PET) film. It was coated with a bar so that the wet film thickness was 15 μm, and dried in an oven at 100° C. for 5 minutes to form a silver nanowire coating film. Then, an overcoat liquid (solid content concentration: about 1%) was applied to the surface of the silver nanowire coating film using a wire bar so that the wet film thickness was 10 μm, and dried in an oven at 100° C. for 5 minutes. Then, an active energy ray was applied to cure the overcoat film to prepare a metal film having a configuration of PET film/silver nanowire layer/overcoat layer (thickness: 100 nm). This metal film was attached to a glass plate having a thickness of 0.5 mm using an adhesive (15 μm) to obtain a laminate of metal film/adhesive/glass plate. The resistance value of the obtained laminate was measured with a non-contact resistance measuring device (manufactured by Napson Co., Ltd., product name: "EC-80") and found to be 50Ω/□.

A polarizing plate with a retardation layer or a polarizing plate obtained in Examples and Comparative Examples was attached to the surface of the overcoat layer of the metal film of the laminate to prepare a test sample. The resistance value of this test sample was measured with a non-contact resistance measuring instrument and taken as the initial resistance value. Furthermore, after subjecting the test sample to a reliability test (placed in an environment of 85 ° C. and 85% RH for 48 hours and then left in an environment of 23 ° C. and 55% RH for 2 hours), the resistance value was measured in the same manner as above. was measured. The resistance value increase rate was calculated by the following formula. When the measured value (resistance value) exceeded the measurement limit (1000Ω/□) of the non-contact resistance measuring instrument, the measured value was assumed to be 1500Ω/□.
Resistance value increase rate (%) = {(resistance value after reliability test - initial resistance value) / initial resistance value} x 100
Furthermore, evaluation was made according to the following criteria.
Good: Resistance value increase rate is less than 200% Bad: Resistance value increase rate is 200% or more

(7) Metal corrosiveness (200 hours)
The retardation layer-equipped polarizing plates obtained in Examples and Comparative Examples were attached to the overcoat layer forming surface of the metal film of the laminate obtained in (2) to obtain test samples. The resistance value of this test sample was measured with a non-contact resistance meter, and taken as the initial resistance value. Furthermore, after subjecting the test sample to a reliability test (placed in an environment of 85 ° C. and 85% RH for 200 hours and then left in an environment of 23 ° C. and 55% RH for 2 hours), the resistance value was measured in the same manner as above. was measured. The resistance value increase rate was calculated by the following formula. When the measured value (resistance value) exceeded the measurement limit (1000Ω/□) of the non-contact resistance measuring instrument, the measured value was assumed to be 1500Ω/□.
Resistance value increase rate (%) = {(resistance value after reliability test - initial resistance value) / initial resistance value} x 100
Furthermore, evaluation was made according to the following criteria.
Excellent: Resistance value increase rate is less than 200% Good: Resistance value increase rate is 200% or more and less than 2000% Poor: Resistance value increase rate is 2000% or more

[Example 1]
1. Production of Polarizer As a thermoplastic resin substrate, a long amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a water absorption of 0.75% and a Tg of about 75° C. was used. Corona treatment was applied to one side of the resin substrate.
Polyvinyl alcohol (degree of polymerization: 4,200, degree of saponification: 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOSEFIMER Z410") mixed at 9:1: 100 weight of PVA-based resin A PVA aqueous solution (coating solution) was prepared by adding 13 parts by weight of potassium iodide.
The above PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60° C. to form a PVA-based resin layer having a thickness of 13 μm, thereby producing a laminate.
The obtained laminate was uniaxially stretched 2.4 times at the free end in the machine direction (longitudinal direction) between rolls with different peripheral speeds in an oven at 130° C. (in-air auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath (an aqueous boric acid 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 (insolubilizing treatment).
Then, the finally obtained polarizer is added to a dyeing bath (iodine aqueous solution obtained by blending iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30 ° C. It was immersed for 60 seconds while adjusting the concentration so that the single transmittance (Ts) was 43.0% or more (dyeing treatment).
Next, it was immersed for 30 seconds in a cross-linking bath at a liquid temperature of 40°C (an aqueous solution of boric acid obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water). (crosslinking treatment).
After that, while immersing the laminate in an aqueous solution of boric acid (boric acid concentration: 4.0% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70°C, the laminate is placed between rolls having different peripheral speeds in the vertical direction (longitudinal direction). Then, the film was uniaxially stretched so that the total draw ratio was 5.5 times (underwater stretching treatment).
After that, the laminate was immersed in a washing bath (aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (washing treatment).
After that, while drying in an oven kept at 90° C., it was brought into contact with a heating roll made of SUS whose surface temperature was kept at 75° C. for about 2 seconds (drying shrinkage treatment). The shrinkage ratio in the width direction of the laminate due to the drying shrinkage treatment was 5.2%.
Thus, a polarizer having a thickness of 5 μm was formed on the resin substrate.

2. Preparation of Polarizing Plate An HC-COP film as a protective layer was attached to the surface of the polarizer obtained above (the surface opposite to the resin substrate) via an ultraviolet curable adhesive. Specifically, the curable adhesive was applied so as to have a total thickness of 1.0 μm, and was bonded using a roll machine. After that, UV rays were applied from the protective layer side to cure the adhesive. The HC-COP film is a film in which a hard coat (HC) layer (thickness 2 μm) is formed on a cycloolefin (COP) film (manufactured by Zeon Corporation, product name “ZF12”, thickness 25 μm), and the COP film was placed on the polarizer side. Then, the resin substrate was peeled off to obtain a polarizing plate having a structure of protective layer (HC layer/COP film)/adhesive layer/polarizer.

ポリエチレンテレフタレート（ＰＥＴ）フィルム（厚み３８μｍ）表面を、ラビング布を用いてラビングし、配向処理を施した。配向処理の方向は、偏光板に貼り合わせる際に偏光子の吸収軸の方向に対して視認側から見て１５°方向となるようにした。この配向処理表面に、上記液晶塗工液をバーコーターにより塗工し、９０℃で２分間加熱乾燥することによって液晶化合物を配向させた。このようにして形成された液晶層に、メタルハライドランプを用いて１ｍＪ/ｃｍ^２の光を照射し、当該液晶層を硬化させることによって、ＰＥＴフィルム上に液晶配向固化層Ａを形成した。液晶配向固化層Ａの厚みは２．５μｍ、面内位相差Ｒｅ（５５０）は２７０ｎｍであった。さらに、液晶配向固化層Ａは、ｎｘ＞ｎｙ＝ｎｚの屈折率分布を有していた。
塗工厚みを変更したこと、および、配向処理方向を偏光子の吸収軸の方向に対して視認側から見て７５°方向となるようにしたこと以外は上記と同様にして、ＰＥＴフィルム上に液晶配向固化層Ｂを形成した。液晶配向固化層Ｂの厚みは１．５μｍ、面内位相差Ｒｅ（５５０）は１４０ｎｍであった。さらに、液晶配向固化層Ｂは、ｎｘ＞ｎｙ＝ｎｚの屈折率分布を有していた。 3. Production of the first alignment fixed layer and the second alignment fixed layer constituting the retardation layer Polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name “Paliocolor LC242”, represented by the following formula) 10 g , 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).

The surface of a polyethylene terephthalate (PET) film (thickness: 38 μm) was rubbed with a rubbing cloth and subjected to orientation treatment. The direction of the orientation treatment was set to be 15° from the direction of the absorption axis of the polarizer when viewed from the viewing side when attached to the polarizing plate. The above liquid crystal coating solution was applied to the alignment-treated surface using a bar coater, and dried by heating at 90° C. for 2 minutes to align the liquid crystal compound. A metal halide lamp was used to irradiate the liquid crystal layer thus formed with light of 1 mJ/cm ² to cure the liquid crystal layer, thereby forming a liquid crystal alignment fixed layer A on the PET film. The liquid crystal alignment fixed layer A had a thickness of 2.5 μm and an in-plane retardation Re (550) of 270 nm. Furthermore, the liquid crystal alignment fixed layer A had a refractive index distribution of nx>ny=nz.
In the same manner as above, except that the coating thickness was changed and that the alignment treatment direction was set to be 75° to the direction of the absorption axis of the polarizer when viewed from the viewing side, A liquid crystal alignment fixed layer B was formed. The liquid crystal alignment fixed layer B had a thickness of 1.5 μm and an in-plane retardation Re (550) of 140 nm. Furthermore, the liquid crystal alignment fixed layer B had a refractive index distribution of nx>ny=nz.

4. Formation of retardation layer 2. The polarizer surface of the polarizing plate obtained in 3. above. The liquid crystal alignment fixed layer A and the liquid crystal alignment fixed layer B obtained in 1. were transferred in this order. At this time, the angle between the absorption axis of the polarizer and the slow axis of the liquid crystal alignment fixed layer A is 15°, and the angle between the absorption axis of the polarizer and the slow axis of the liquid crystal alignment fixed layer B is 75°. Transfer (bonding) was carried out in this manner. It should be noted that each transfer (bonding) is the same as in 2. above. It was performed through the ultraviolet curable adhesive (thickness 1.0 μm) used in . Thus, protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive layer/retardation layer (first liquid crystal alignment fixed layer/adhesive layer/second liquid crystal alignment fixed layer) A laminate having the structure was produced.

5. Preparation of polarizing plate with retardation layer 20 parts of acrylic resin (manufactured by Kusumoto Kasei Co., Ltd., product name “B-811”, Tg: 110 ° C., Mw: 40000) is dissolved in 80 parts of methyl ethyl ketone to obtain a resin solution (20%). got This resin solution was prepared according to the above 4. The surface of the second liquid crystal alignment solidified layer of the laminate obtained in 1. is coated using a wire bar, and the coated film is dried at 60 ° C. for 5 minutes to form a solidified product of the coated film of the organic solvent solution of the resin. An iodine permeation suppressing layer (thickness: 0.5 µm) was formed. Next, a pressure-sensitive adhesive layer (thickness 15 μm) is provided on the surface of the iodine permeation suppression layer, and a protective layer (HC layer / COP film) / adhesive layer / polarizer / adhesive layer / retardation layer (first liquid crystal alignment fixed layer A polarizing plate with a retardation layer having a structure of /adhesive layer/second liquid crystal alignment fixed layer)/iodine permeation suppressing layer/adhesive layer was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 39.5 μm. The obtained polarizing plate with a retardation layer was subjected to the above evaluations (4) to (7). Furthermore, with respect to metal corrosiveness, comparison was made with Comparative Example 1 (described later) in which an iodine permeation suppression layer was not formed. Table 1 shows the results.

[Example 2]
Methyl methacrylate (MMA, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "methyl methacrylate monomer") 97.0 parts, 3.0 parts of the copolymerization monomer represented by the above general formula (1e), polymerization initiation In 200 parts of toluene was dissolved 0.2 parts of an agent (trade name “2,2′-azobis(isobutyronitrile)” manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.). Then, a polymerization reaction was carried out for 5.5 hours while heating at 70° C. in a nitrogen atmosphere to obtain a boron-containing acrylic resin solution (solid concentration: 33%). The resulting boron-containing acrylic polymer had a Tg of 110°C and an Mw of 80,000. Retardation layer in the same manner as in Example 1 except that the boron-containing acrylic polymer was used instead of the acrylic resin "B-811" and the thickness of the iodine permeation suppression layer was set to 0.3 μm. A polarizing plate was prepared. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Results are shown in Tables 1 and 2.

[Example 3]
A polarizing plate with a retardation layer was produced in the same manner as in Example 2, except that the thickness of the iodine permeation suppressing layer was 0.5 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Results are shown in Tables 1 and 2.

[Example 4]
Examples except that a thermoplastic epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name "jER (registered trademark) 1256B40", Tg: 100 ° C., Mw: 45000) was used instead of the acrylic resin "B-811". A polarizing plate with a retardation layer was produced in the same manner as in Example 1. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Results are shown in Tables 1 and 2.

[Example 5]
Thermoplastic epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name “jER (registered trademark) YX7200B35”, Tg: 150 ° C., Mw: 30000) was used instead of the acrylic resin “B-811”, and iodine A polarizing plate with a retardation layer was produced in the same manner as in Example 1, except that the thickness of the transmission suppression layer was 0.3 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Results are shown in Tables 1 and 2.

[Example 6]
A polarizing plate with a retardation layer was produced in the same manner as in Example 5, except that the thickness of the iodine permeation suppressing layer was 0.5 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Results are shown in Tables 1 and 2.

[Example 7]
Instead of the acrylic resin "B-811", 15 parts of "B-811" and a thermoplastic epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name "jER (registered trademark) YX6954BH30") 85 parts (solid content conversion) and A polarizing plate with a retardation layer was produced in the same manner as in Example 1 except that a blend of No. The blend had a Tg of 125°C and a Mw of 38,000. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Results are shown in Tables 1 and 2.

[Example 8]
Example 1-2. The resin blend used in Example 7 was applied and dried on the polarizer side of the polarizing plate having the structure of protective layer (HC layer / COP film) / adhesive layer / polarizer obtained in , and the resin organic An iodine permeation suppressing layer (thickness: 0.5 μm) was formed as a solidified product of the coating film of the solvent solution. Liquid crystal alignment fixed layer A and liquid crystal alignment fixed layer B were transferred in this order to the surface of the iodine permeation suppression layer in the same manner as in Example 1, and protective layer (HC layer / COP film) / adhesive layer / polarizer / iodine permeation A retardation layer-attached polarizing plate having a structure of suppression layer/adhesive layer/retardation layer (first liquid crystal orientation fixed layer/adhesive layer/second liquid crystal orientation fixed layer)/adhesive layer was obtained. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Results are shown in Tables 1 and 2.

[Example 9]
A laminate having a structure of protective layer (HC layer/COP film)/adhesive layer/polarizer/iodine permeation suppressing layer in the same manner as in Example 8 except that the boron-containing acrylic polymer in Example 2 was used. made the body. Next, a blend of 15 parts of the boron-containing acrylic polymer in Example 2 and 85 parts of a thermoplastic epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name "jER (registered trademark) YX6954BH30") (in terms of solid content) was used. Protective layer (HC layer/COP film)/adhesive layer/polarizer/iodine permeation suppression layer/adhesive layer/retardation layer (first liquid crystal alignment fixed layer/adhesive A polarizing plate with a retardation layer having a structure of agent layer/second liquid crystal alignment solidifying layer)/iodine permeation suppressing layer/adhesive layer was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 40 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Table 2 shows the results.

[Example 10]
15 parts of the boron-containing acrylic polymer obtained in Example 2 and a thermoplastic epoxy resin ( Mitsubishi Chemical Corporation, trade name "jER (registered trademark) YX6954BH30") 85 parts (solid content conversion) was used in the same manner as in Example 9, to obtain a polarizing plate with a retardation layer. . The total thickness of the obtained polarizing plate with a retardation layer was 40 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Table 2 shows the results.

[Example 11]
An iodine permeation suppressing layer formed between the polarizer and the retardation layer and adjacent to the polarizer is placed between the polarizer and the retardation layer and adjacent to the retardation layer. Protective layer (HC layer/COP film)/adhesive layer/polarizer/adhesive layer/iodine permeation suppression layer/retardation layer (first liquid crystal alignment fixed layer A polarizing plate with a retardation layer having a structure of /adhesive layer/second liquid crystal alignment fixed layer)/iodine permeation suppressing layer/adhesive layer was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 40 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Table 2 shows the results.

[Example 12]
As in Example 9, a protective layer (HC layer / COP film) / adhesive layer / polarizer / iodine permeation suppression layer / adhesive layer / iodine permeation suppression layer / retardation layer (first liquid crystal alignment fixed layer / adhesive layer / second liquid crystal alignment fixed layer )/iodine permeation suppressing layer/adhesive layer to obtain a polarizing plate with a retardation layer. The total thickness of the obtained polarizing plate with a retardation layer was 40.5 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Table 2 shows the results.

[Comparative Example 1]
A polarizing plate with a retardation layer was produced in the same manner as in Example 1, except that the iodine permeation suppressing layer was not formed. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Results are shown in Tables 1 and 2.

[Comparative Example 2]
Retardation layer in the same manner as in Example 1 except that the acrylic resin "B-723" (manufactured by Kusumoto Kasei Co., Ltd., Tg: 54 ° C., Mw: 200000) was used instead of the acrylic resin "B-811". A polarizing plate was prepared. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Results are shown in Tables 1 and 2.

[Comparative Example 3]
A photocurable epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name "jER (registered trademark) 828", using "CPI100P" manufactured by San-Apro Co., Ltd. as a photopolymerization initiator) instead of the acrylic resin "B-811". A polarizing plate with a retardation layer was produced in the same manner as in Example 1, except that The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Results are shown in Tables 1 and 2.

[Comparative Example 4]
In the same manner as in Example 1, except that a PVA resin (manufactured by Mitsubishi Chemical Corporation, trade name "Gosenol Z200", Tg: 80 ° C., Mw: 8800) was used instead of the acrylic resin "B-811". A polarizing plate with a retardation layer was produced. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Results are shown in Tables 1 and 2.

[Reference example 1]
1. Preparation of Polarizing Plate A polarizing plate having a structure of protective layer (HC layer/COP film)/polarizer was obtained in the same manner as in Example 1.

2. Preparation of Retardation Film Constituting Retardation Layer 2-1. Polymerization of polyester carbonate-based resin Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with a stirring blade and a reflux condenser controlled at 100°C. Bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane 29.60 parts by mass (0.046 mol), isosorbide (ISB) 29.21 parts by mass (0.200 mol), spiroglycol (SPG) 42 .28 parts by mass (0.139 mol), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC) and 1.19 × 10 ^-2 parts by weight of calcium acetate monohydrate as a catalyst (6.78 × 10 ^{- 5} mol) was charged. After the interior of the reactor was replaced with nitrogen under reduced pressure, heating was performed with a heating medium, and stirring was started when the internal temperature reached 100°C. After 40 minutes from the start of heating, the internal temperature was allowed to reach 220°C, and the pressure was reduced at the same time as controlling to maintain this temperature. Phenol vapor produced as a by-product of the polymerization reaction was led to a reflux condenser at 100°C, a small amount of monomer components contained in the phenol vapor was returned to the reactor, and uncondensed phenol vapor was led to a condenser at 45°C and recovered. After nitrogen was introduced into the first reactor and the pressure was once restored to atmospheric pressure, the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, the temperature rise and pressure reduction in the second reactor were started, and the internal temperature was brought to 240° C. and the pressure to 0.2 kPa in 50 minutes. After that, polymerization was allowed to proceed until a predetermined stirring power was obtained. When a predetermined power was reached, nitrogen was introduced into the reactor to restore the pressure, the polyester carbonate-based resin produced was extruded into water, and strands were cut to obtain pellets.

2-2. Preparation of retardation film After vacuum drying the obtained polyester carbonate resin (pellet) at 80 ° C. for 5 hours, a single screw extruder (Toshiba Machine Co., Ltd., cylinder setting temperature: 250 ° C.), T die (width 200 mm , set temperature: 250° C.), a chill roll (set temperature: 120 to 130° C.), and a winder were used to prepare a long resin film having a thickness of 135 μm. The obtained long resin film was stretched in the width direction at a stretching temperature of 133° C. and a stretching ratio of 2.8 to obtain a retardation film with a thickness of 53 μm. Re(550) of the obtained retardation film was 141 nm, Re(450)/Re(550) was 0.82, and Nz coefficient was 1.12.

3. Production of polarizing plate with retardation layer 1 above. The polarizer surface of the polarizing plate obtained in 2. above. The retardation film obtained in 1. was pasted together via an acrylic pressure-sensitive adhesive (thickness: 5 μm). At this time, they were attached so that the absorption axis of the polarizer and the slow axis of the retardation film formed an angle of 45°. Furthermore, the same pressure-sensitive adhesive layer as in Example 1 was provided on the surface of the retardation layer. Thus, a polarizing plate with a retardation layer having a structure of protective layer/adhesive layer/polarizer/adhesive layer/retardation layer (stretched resin film)/adhesive layer was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 91 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. Results are shown in Tables 1 and 2.

[Example 13]
A polarizing plate having a structure of protective layer (HC layer/COP film)/adhesive layer/polarizer/iodine permeation suppression layer/adhesive layer in the same manner as in Example 1, except that no retardation layer was formed. got The total thickness of the obtained polarizing plate was 33.5 μm. The obtained polarizing plate was subjected to the same evaluation as in Example 1. Results are shown in Tables 1 and 2. Since this example is a polarizing plate and has a different structure from the polarizing plate with a retardation layer, comparison with Comparative Example 1 was not made with respect to metal corrosiveness.

[evaluation]
As is clear from Table 1, the polarizing plate with a retardation layer and the polarizing plate of Examples of the present invention are formed by forming a predetermined iodine permeation suppressing layer and setting the iodine existence index of the pressure-sensitive adhesive layer to a predetermined value or less. , can reduce the change in the degree of polarization in a high-temperature and high-humidity environment, and has excellent durability. Further, the retardation layer-attached polarizing plate and the polarizing plate of the examples of the present invention can remarkably suppress metal corrosiveness and an increase in reflectance in a high-temperature and high-humidity environment. Furthermore, as is clear from Reference Example 1, such changes in degree of polarization, increase in reflectance, and corrosion to metal are problems specific to very thin retardation layer-attached polarizing plates and polarizing plates. As is clear from a comparison between Example 1 and Example 13, the presence or absence of the liquid crystal alignment fixed layer (very thin retardation layer) does not substantially affect the effects of the present invention.

As is clear from Table 2, the retardation layer-equipped polarizing plates of Examples 9 to 12 of the present invention contained two or three iodine permeation suppressing layers, so that they were kept in a high-temperature and high-humidity environment for a long time (200 hours). ) can remarkably suppress metal corrosiveness even when it is charged. Therefore, it can be seen that the polarizing plates with retardation layers of Examples 9 to 12 of the present invention can remarkably suppress corrosion of metal members when applied to an image display device.

The polarizing plate of the present invention is suitably used for liquid crystal display devices, organic EL display devices and inorganic EL display devices. The retardation layer-attached polarizing plate of the present invention is suitably used as a circularly polarizing plate for liquid crystal display devices, organic EL display devices and inorganic EL display devices.

REFERENCE SIGNS LIST 10 polarizing plate 11 polarizer 12 protective layer 20 retardation layer 30 adhesive layer 40 iodine permeation suppression layer 100 polarizing plate with retardation layer 101 polarizing plate with retardation layer 102 polarizing plate with retardation layer 103 polarizing plate with retardation layer 104 polarizing plate with retardation layer 105 polarizing plate with retardation layer

Claims (10)

Having a polarizer, an iodine permeation suppressing layer and an adhesive layer in this order, the iodine existence index of the adhesive layer being 0.050 or less,
The iodine permeation suppressing layer is a solidified coating film of an organic solvent solution of a thermoplastic resin,
Polymerizing a monomer mixture in which the thermoplastic resin contains more than 50 parts by weight of a (meth)acrylic monomer and more than 0 parts by weight and less than 50 parts by weight of a monomer represented by formula (1) A polarizing plate comprising a copolymer obtained by:

(Wherein, X is a vinyl group, a (meth)acryl group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetane group, a hydroxyl group, an amino group, an aldehyde group, and a group consisting of a carboxyl group Represents a selected functional group containing at least one reactive group, and R ¹ and R ² each independently represent a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, or a substituted or an optionally substituted heterocyclic group, and R ¹ and R ² may be linked together to form a ring). 2. The polarizing plate according to claim 1, wherein the resin constituting said iodine permeation suppressing layer has a glass transition temperature of 85[deg.] C. or higher and a weight average molecular weight Mw of 25000 or higher. 2. The polarizing plate according to claim 1, wherein two or more layers of said iodine permeation suppressing layer are provided between said polarizer and said adhesive layer. 4. The polarizing plate according to claim 1, wherein the iodine permeation suppression layer has a thickness of 0.05 μm to 10 μm. A polarizing plate according to any one of claims 1 to 4, and a retardation layer disposed between the polarizer and the adhesive layer,
wherein the retardation layer is an aligned and fixed layer of a liquid crystal compound having a circularly polarized light function or an elliptically polarized light function;
A polarizing plate with a retardation layer. The retardation layer is a single layer,
Re (550) of the retardation layer is 100 nm to 190 nm,
The angle formed by the slow axis of the retardation layer and the absorption axis of the polarizer is 40° to 50°,
The polarizing plate with a retardation layer according to claim 5. The retardation layer has a laminated structure of a first liquid crystal compound alignment fixed layer and a second liquid crystal compound alignment fixed layer,
Re (550) of the alignment fixed layer of the first liquid crystal compound is 200 nm to 300 nm, the angle formed by the slow axis and the absorption axis of the polarizer is 10 ° to 20 °,
Re (550) of the alignment fixed layer of the second liquid crystal compound is 100 nm to 190 nm, and the angle formed by the slow axis and the absorption axis of the polarizer is 70 ° to 80 °.
The polarizing plate with a retardation layer according to claim 6. The polarizing plate with a retardation layer according to any one of claims 5 to 7, having a total thickness of 60 µm or less. An image display device comprising the polarizing plate according to any one of claims 1 to 4 or the polarizing plate with a retardation layer according to any one of claims 5 to 8. 10. The image display device according to claim 9, which is an organic electroluminescence display device or an inorganic electroluminescence display device.

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