KR20230016182A - Polarizing plate having a retardation layer and an adhesive layer and an organic electroluminescent display device using the same - Google Patents

Abstract

A polarizing plate provided with a retardation layer and an adhesive layer, which is excellent in durability in a high-temperature, high-humidity environment, and in which discoloration is remarkably suppressed when applied to an organic EL display device is provided. A polarizing plate having a retardation layer and a pressure-sensitive adhesive layer of the present invention includes a polarizer and a polarizing plate including a protective layer on at least the visible side of the polarizer, a retardation layer bonded to the opposite side of the polarizing plate through a first adhesive layer, and a phase difference It has a second pressure-sensitive adhesive layer disposed as an outermost layer on the side opposite to the polarizing plate of the layer. The first pressure sensitive adhesive layer or the second pressure sensitive adhesive layer contains acrylic acid as a monomer component of the base polymer and further contains a conductive agent of an inorganic cation salt. The content of the conductive agent is 0.4 parts by weight to 12 parts by weight with respect to 100 parts by weight of the base polymer of the pressure-sensitive adhesive layer.

Description

Polarizing plate having a retardation layer and an adhesive layer and an organic electroluminescent display device using the same

The present invention relates to a polarizing plate provided with a retardation layer and an adhesive layer, and an organic electroluminescent (EL) display device using the same.

[0002] In recent years, with the spread of thin displays, displays (organic EL display devices) equipped with organic EL panels have been proposed. Since the organic EL panel has a highly reflective metal layer, problems such as reflection of external light and reflection of the background tend to occur. Then, it is known to prevent these problems by providing a circularly polarizing plate on the viewing side (for example, Patent Documents 1 to 3). However, there is a problem that the circularly polarizing plate provided in the organic EL display device is easily discolored. Further, in circular polarizing plates, improvement in durability under high-temperature, high-humidity environments is continuously required.

Japanese Unexamined Patent Publication No. 2003-311239 Japanese Unexamined Patent Publication No. 2002-372622 Japanese Patent No. 3325560

The present invention has been made to solve the above conventional problems, and its main object is to provide a retardation layer and pressure-sensitive adhesive which are excellent in durability in a high-temperature, high-humidity environment and have significantly suppressed discoloration when applied to an organic EL display device. It is to provide a polarizing plate having a layer.

A polarizing plate having a retardation layer and a pressure-sensitive adhesive layer of the present invention includes a polarizer and a polarizing plate including a protective layer on at least the visible side of the polarizer, and a retardation layer bonded through a first adhesive layer on the opposite side of the visible side of the polarizing plate , and a second pressure-sensitive adhesive layer disposed as an outermost layer on the opposite side of the retardation layer to the polarizing plate. The first pressure-sensitive adhesive layer or the second pressure-sensitive adhesive layer contains acrylic acid as a monomer component of the base polymer and further contains a conductive agent of an inorganic cation salt. The content of the conductive agent is 0.4 parts by weight to 12 parts by weight with respect to 100 parts by weight of the base polymer of the pressure-sensitive adhesive layer.

In one embodiment, the acrylic acid content in the monomer component is 0.1% by weight to 10% by weight.

In one embodiment, the said 1st adhesive layer contains acrylic acid as a monomer component of a base polymer, and also contains the electrically conductive agent of an inorganic cation salt.

In one embodiment, the polarizer and the retardation layer are bonded via the first pressure-sensitive adhesive layer.

In one embodiment, the inorganic cation salt is a lithium salt.

In one embodiment, the water vapor transmission rate of the protective layer on the visual recognition side is 200 g/m 2 24 h or less.

According to another aspect of the present invention, an organic electroluminescent display device is provided. This organic electroluminescent display device is equipped with the polarizing plate provided with said retardation layer and an adhesive layer.

According to an embodiment of the present invention, in a polarizing plate having a retardation layer and a pressure-sensitive adhesive layer, a pressure-sensitive adhesive layer for laminating the polarizing plate and the retardation layer or a pressure-sensitive adhesive layer for bonding the polarizing plate including the retardation layer and the pressure-sensitive adhesive layer to an image display cell By introducing a predetermined amount of a conductive agent (inorganic cation salt) and further containing acrylic acid as a monomer component of the base polymer of the pressure-sensitive adhesive layer, the durability in a high-temperature, high-humidity environment is excellent, and when applied to an organic EL display device. Thus, a polarizing plate provided with a retardation layer and an adhesive layer in which discoloration is significantly suppressed can be realized.

1 is a schematic cross-sectional view of a polarizing plate provided with a retardation layer and an adhesive layer according to one embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described, this invention is not limited to these embodiment.

(Definition of Terms and Symbols)

The definitions of terms and symbols in this specification 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 maximized (i.e., the slow axis direction), "ny" is the refractive index in the in-plane direction orthogonal to the slow axis (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction.

(2) In-plane retardation (Re)

"Re(λ)" is an in-plane phase difference measured with light having a wavelength of λnm at 23°C. For example, "Re(550)" is an 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 when the thickness of the layer (film) is d(nm).

(3) Phase difference in thickness direction (Rth)

"Rth(λ)" is the phase difference in the thickness direction measured with light having a wavelength of λnm at 23°C. For example, "Rth (550)" is the phase difference in the thickness direction measured with light having a wavelength of 550 nm at 23°C. Rth(λ) is obtained by the formula: Rth(λ)=(nx-nz)×d when the thickness of the layer (film) is d(nm).

(4) Nz factor

The Nz coefficient is obtained by Nz = Rth/Re.

(5) Angle

When referred to as an angle in this specification, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Thus, for example, "45°" means ±45°.

A. Overall configuration of a polarizing plate having a retardation layer and an adhesive layer

1 is a schematic cross-sectional view of a polarizing plate provided with a retardation layer and an adhesive layer according to one embodiment of the present invention. The polarizing plate 100 provided with the retardation layer and the pressure-sensitive adhesive layer in the illustrated example includes the polarizing plate 10, the retardation layer 30 bonded to the polarizing plate 10 through the first pressure-sensitive adhesive layer 20, and the retardation layer 30. It has a second pressure-sensitive adhesive layer 40 provided as an outermost layer on the opposite side of the polarizing plate 10 of . By the second adhesive layer 40, the polarizing plate provided with the retardation layer and the adhesive layer can be attached to the image display cell. The polarizing plate 10 includes a polarizer 11 and a protective layer (visible side protective layer) 12 at least on the visible side of the polarizer 11 . In the illustrated example, a protective layer (inner protective layer) 13 is provided on the side opposite to the viewing side of the polarizer 11, but the protective layer 13 can be omitted preferably. That is, the polarizer 11 and the retardation layer 30 may be bonded through the first pressure sensitive adhesive layer 20 . In the configuration in which the inner protective layer 13 is omitted, the effect of the embodiment of the present invention is remarkable. Practically, it is preferable that a release film is temporarily attached to the surface of the second pressure-sensitive adhesive layer 40 until the polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer is put into use. By temporarily attaching the peeling film, roll formation of the polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer becomes possible while protecting the second pressure-sensitive adhesive layer.

In the embodiment of the present invention, the first pressure sensitive adhesive layer 20 or the second pressure sensitive adhesive layer 40 contains acrylic acid as a monomer component of the base polymer and further contains a conductive agent of an inorganic cation salt. By introducing a combination of a conductive agent of an inorganic cationic salt and acrylic acid into either the first pressure-sensitive adhesive layer 20 or the second pressure-sensitive adhesive layer 40, durability in a high-temperature, high-humidity environment is excellent, and applied to an organic EL display device. In this case, it is possible to realize a polarizing plate having a retardation layer and an adhesive layer in which discoloration is significantly suppressed. The inventors of the present invention, when a polarizing plate provided with a retardation layer and a pressure-sensitive adhesive layer is applied to an organic EL display device, faced with a new problem that the polarizing plate provided with a retardation layer and a pressure-sensitive adhesive layer is discolored, and as a result of intensive examination of the problem, It was found that the cause of discoloration was ammonia (actually, ammonium ions) generated from the organic EL panel. In addition, as a result of intensive examination of means for suppressing discoloration by ammonia, a predetermined amount of a pressure-sensitive adhesive layer for laminating a polarizing plate and a retardation layer or a pressure-sensitive adhesive layer for bonding a polarizing plate having a retardation layer and a pressure-sensitive adhesive layer to an image display cell is used. It was found that the discoloration can be remarkably suppressed by introducing a conductive agent (inorganic cation salt) and further containing acrylic acid as a monomer component of the base polymer of the pressure-sensitive adhesive layer. That is, the embodiment of the present invention is to solve such a newly discovered subject. The conductive agent (inorganic cation salt) is preferably a lithium salt. The content of the conductive agent is 0.4 parts by weight to 12 parts by weight, preferably 0.5 parts by weight to 10 parts by weight, more preferably 2 parts by weight to 8 parts by weight, based on 100 parts by weight of the base polymer of the pressure-sensitive adhesive layer. When there is too much content of a conductive agent, durability in a high-temperature, high-humidity environment of a polarizing plate provided with a retardation layer and an adhesive layer may become inadequate. If the content of the conductive agent is too small, discoloration may occur when the polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer is applied to an organic EL display device. The acrylic acid content in the monomer component is preferably 0.1% by weight to 10% by weight, more preferably 0.2% by weight to 8% by weight, still more preferably 0.2% by weight to 6% by weight. By introducing acrylic acid into the monomer component of the base polymer of either the first pressure sensitive adhesive layer 20 or the second pressure sensitive adhesive layer 40, when a polarizing plate having a retardation layer and a pressure sensitive adhesive layer is applied to an organic EL display device, remarkable discoloration occurs. can be suppressed. Preferably, the first pressure-sensitive adhesive layer 20 contains acrylic acid as a monomer component of the base polymer and further contains a conductive agent of an inorganic cation salt. With such a configuration, the effect of the embodiment of the present invention is remarkable. It is presumed that this is because the cation of the conductive agent (typically, lithium ion) not only captures ammonium ion, but also the iodine complex in the polarizer is stabilized by the lithium ion. In addition, these assumptions do not limit the present invention nor are they constrained by the assumptions. In addition, the effect that the first pressure-sensitive adhesive layer contains a conductive agent or the like is particularly remarkable in a configuration in which the inner protective layer 13 is omitted. Since the first pressure-sensitive adhesive layer is adjacent to the polarizer, it is presumed that movement of lithium ions to the polarizer and bonding with iodine complexes (actually, iodine ions in the complex) become easy.

The water vapor transmission rate of the visual side protective layer 12 is typically 200 g/m 2 24 h or less, preferably 160 g/m 2 24 h or less, more preferably 100 g/m 2 24 h or less, still more preferably 50 g / m 2 24 h or less, particularly preferably 30 g / m 2 24 h or less. The lower limit of the water vapor permeability of the visual side protective layer 12 may be, for example, 1 g/m 2 24h. By omitting the inner protective layer 13 and setting the water permeability of the visual side protective layer 12 within this range, the effect of incorporating the conductive agent and acrylic acid into the pressure-sensitive adhesive layer becomes remarkable. In addition, moisture permeability can be measured according to JIS Z 0208.

The total thickness of the polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer is preferably 120 μm or less, more preferably 100 μm or less. The lower limit of the total thickness may be, for example, 45 μm. A polarizing plate including the retardation layer and the pressure-sensitive adhesive layer having such a total thickness can have extremely excellent flexibility and bending durability. As a result, the polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer can be particularly suitably applied to a curved organic EL display device and/or a curved or bendable organic EL display device.

The polarizing plate provided with the phase difference layer and the pressure-sensitive adhesive layer may further have another phase difference layer (not shown) between the phase difference layer 30 and the second pressure-sensitive adhesive layer 40 . Another retardation layer is, typically, a so-called positive C plate whose refractive index characteristic shows a relationship of nz > nx = ny. By providing such another retardation layer, reflection in an oblique direction can be satisfactorily prevented, and a wide viewing angle of the anti-reflection function becomes possible.

The polarizing plate provided with the retardation layer and the adhesive layer may further contain other optical function layers. The type, characteristics, number, combination, arrangement position, and the like of the optical functional layers that can be provided on the polarizing plate including the retardation layer and the pressure-sensitive adhesive layer can be appropriately set according to the purpose. For example, the polarizing plate provided with a retardation layer and an adhesive layer may further have an isotropic base material provided with a conductive layer or a conductive layer (neither is shown). The conductive layer or the isotropic substrate provided with the conductive layer is typically provided on the outer side of the retardation layer 30 (on the side opposite to the polarizing plate 10). When a conductive layer or an isotropic base material having a conductive layer is provided, a polarizing plate having a retardation layer and an adhesive layer can be applied to a so-called inner touch panel type input display device in which a touch sensor is embedded between an organic EL cell and a polarizing plate. there is. For example, the polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer may further contain other retardation layers. Other optical characteristics of the retardation layer (eg, refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, placement position, etc. may be appropriately set depending on the purpose.

The polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer may be sheet-like or elongated. In this specification, "elongated shape" means an elongated shape whose length is sufficiently long with respect to width, and includes, for example, an elongated shape whose length is 10 times or more, preferably 20 times or more, with respect to width. The polarizing plate provided with the elongate retardation layer and the adhesive layer can be wound in roll shape.

Hereinafter, the components of the polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer will be described in more detail.

B. Polarizer

B-1. polarizer

As the polarizer 11, any suitable polarizer can be employed. For example, a single layer resin film may be sufficient as the resin film which forms a polarizer, or a laminated body of two or more layers may be sufficient as it.

Specific examples of the polarizer composed of a single-layer resin film include polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, hydrophilic polymer films such as ethylene-vinyl acetate copolymer-based partially saponified films, iodine, dichroic dyes, etc. Polyene-based oriented films, such as what was dyed and stretched with a dichroic substance, PVA dehydrated, and polyvinyl chloride dehydrochlorinated, etc. are mentioned. Preferably, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching is used in view of its excellent optical properties.

The dyeing with iodine is performed, for example, by immersing the PVA-based film in an aqueous solution of iodine. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after dyeing treatment, or may be performed while dyeing. Moreover, you may dye after extending|stretching. Swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. are applied to the PVA-based film as necessary. For example, by immersing the PVA-based film in water and washing it with water before dyeing, stains and antiblocking agents on the surface of the PVA-based film can be washed, as well as swelling of the PVA-based film to prevent uneven dyeing.

As a specific example of a polarizer obtained using a laminate, a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and a PVA-based resin layer coated and formed on the resin substrate. A polarizer obtained using a layered product is mentioned. A polarizer obtained by using a laminate of a resin substrate and a PVA-based resin layer coated and formed on the resin substrate, for example, a PVA-based resin solution is applied to the resin substrate, dried to form a PVA-based resin layer on the resin substrate, , Obtaining a laminate of a resin substrate and a PVA-based resin layer; It can be produced by: stretching and dyeing the layered product to make the PVA-based resin layer a polarizer. In this embodiment, extending|stretching typically includes immersing a layered product in boric acid aqueous solution and extending|stretching. Further, the stretching may further include, if necessary, air stretching of the laminate at a high temperature (eg, 95° C. or higher) before stretching in a boric acid aqueous solution. The obtained laminate of the resin substrate/polarizer may be used as it is (that is, the resin substrate may be used as a protective layer for the polarizer), and the resin substrate is peeled from the laminate of the resin substrate/polarizer, and the peeling surface is optionally used according to the purpose. An appropriate protective layer of may be laminated and used. The detail of the manufacturing method of such a polarizer is described in Unexamined-Japanese-Patent No. 2012-73580 and Japanese Patent No. 6470455, for example. As for these publications, the entire description is incorporated herein by reference.

The thickness of the polarizer is preferably 15 μm or less, more preferably 12 μm or less, still more preferably 10 μm or less, and particularly preferably 8 μm or less. On the other hand, the thickness of the polarizer is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 3 μm or more. If the thickness of the polarizer is within this range, curling at the time of heating can be favorably suppressed, and good appearance durability at the time of heating is obtained.

The polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, more preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, still more preferably 99.9% or more.

B-2. protective layer

The visual side protective layer 12 and the inner protective layer 13 (if present) are each composed of any appropriate film that can be used as a protective layer for a polarizer. Examples of the material constituting the inner protective layer 13 include cycloolefin resins such as polynorbornene, (meth)acrylic resins, and polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN). resins, polyolefin-based resins such as polyethylene, and polycarbonate-based resins. Representative examples of (meth)acrylic resins include (meth)acrylic resins having a lactone ring structure. The (meth)acrylic-type resin which has a lactone ring structure, for example, Unexamined-Japanese-Patent No. 2000-230016, Unexamined-Japanese-Patent No. 2001-151814, Unexamined-Japanese-Patent No. 2002-120326, Unexamined-Japanese-Patent No. 2002 -254544 and Japanese Unexamined Patent Publication No. 2005-146084. These publications are incorporated herein by reference. The inner protective layer 13 (if present) is preferably composed of a cycloolefin based resin. Representative examples of the material constituting the visual side protective layer 12 include cellulose-based resins such as triacetyl cellulose (TAC) and resins capable of forming a microporous film (for example, polyurethane-based resin). .

As will be described later, the polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer is typically disposed on the viewing side of the organic EL display device, and the viewing side protective layer 12 is disposed on the viewing side. Therefore, surface treatment such as hard coating treatment, antireflection treatment, anti-sticking treatment, and antiglare treatment may be applied to the visual side protective layer 12 as needed. In addition,/or, if necessary, processing for improving visibility when viewing through polarized sunglasses is applied to the viewing-side protective layer 12 (typically, imparting a (other) circular polarization function, imparting ultra-high retardation) doing) may be implemented. By performing such processing, excellent visibility can be realized even when the display screen is visually recognized through a polarizing lens such as polarized sunglasses. Therefore, the polarizing plate having the retardation layer and the pressure-sensitive adhesive layer can be suitably applied to an organic EL display device that can be used outdoors.

The thickness of the visual side protective layer 12 is preferably 10 μm to 80 μm, more preferably 15 μm to 70 μm, still more preferably 20 μm to 50 μm. In addition, when surface treatment is performed, the thickness of the visual side protective layer 12 is the thickness including the thickness of the surface treatment layer.

In one embodiment, the inner protective layer 13 is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is -10 nm to +10 nm. The thickness of the inner protective layer 13 can also be appropriately set according to the desired moisture permeability. The thickness of the inner protective layer 13 is preferably 10 μm to 80 μm, more preferably 20 μm to 70 μm, still more preferably 30 μm to 50 μm. As described above, the protective layer 13 can preferably be omitted.

C. phase difference layer

The retardation layer 30 may be a single layer or may have a laminated structure (substantially a two-layer structure).

When the retardation layer 30 is a single layer, the retardation layer 30 can typically function as a λ/4 plate. The retardation layer is typically provided to impart antireflection characteristics to the organic EL display device. The retardation layer typically exhibits a relationship of nx>ny=nz in refractive index characteristics. The in-plane retardation Re(550) of the retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, still more preferably 120 nm to 160 nm. In addition, "ny=nz" here includes not only the case where ny and nz are completely different, but also the case where they are substantially equal. Therefore, there may be cases where ny>nz or ny<nz is satisfied within a range that does not impair the effects of the present invention.

The Nz coefficient of the retardation layer is preferably 0.9 to 1.5, more preferably 0.9 to 1.3. By satisfying this relationship, an organic EL display device having a very good reflection color can be obtained.

When the retardation layer is a single layer, the retardation layer preferably exhibits reverse dispersion wavelength characteristics in which the retardation value increases with the wavelength of the measurement light. 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 characteristics can be realized.

The angle between the slow axis of the retardation layer and the absorption axis of the polarizer is preferably 40° to 50°, more preferably 42° to 48°, still more preferably about 45°. If the angle is within this range, an organic EL display device having very excellent antireflection properties can be obtained by using the λ/4 plate as the retardation layer as described above.

The retardation layer may be made of any suitable material as long as it can satisfy the above characteristics. Specifically, the retardation layer may be a stretched film of a resin film or may be an alignment-fixed layer of liquid crystal compounds (hereinafter referred to as a liquid-crystal alignment-fixed layer).

When the retardation layer is a stretched film of a resin film, as a representative example of the resin constituting the resin film, a polycarbonate-based resin or a polyester carbonate-based resin (hereinafter, simply referred to as a polycarbonate-based resin in some cases) ) can be heard. As the polycarbonate-based resin, any suitable polycarbonate-based resin can be used as long as a desired moisture permeability is obtained. For example, the polycarbonate-based resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, an alicyclic diol, an alicyclic dimethanol, and a dihydroxy compound. , tri or polyethylene glycol, and a structural unit derived from at least one dihydroxy compound selected from the group consisting of alkylene glycol and spiro glycol. Preferably, the polycarbonate-based resin comprises a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from alicyclic dimethanol. and/or comprises a structural unit derived from di, tri or polyethylene glycol; More preferably, a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di, tri, or polyethylene glycol are included. The polycarbonate-based resin may contain structural units derived from other dihydroxy compounds as needed. The retardation layer can be formed by stretching a film composed of the above polycarbonate-based resin under any appropriate stretching conditions. In addition, the details of the polycarbonate-based resin and the formation method of the retardation layer are, for example, Japanese Unexamined Patent Publication No. 2014-10291, Japanese Unexamined Patent Publication No. 2014-26266, and Japanese Unexamined Patent Publication No. 2015-212816 , Japanese Unexamined Patent Publication No. 2015-212817, Japanese Unexamined Patent Publication No. 2015-212818, Japanese Unexamined Patent Publication No. 2017-54093, and Japanese Unexamined Patent Publication No. 2018-60014. Descriptions of these publications are incorporated herein by reference.

When the retardation layer is a liquid crystal orientation solidified layer, by using a liquid crystal compound, the difference between nx and ny of the obtained retardation layer can be significantly increased compared to non-liquid crystal materials, so that the thickness of the retardation layer for obtaining the desired in-plane retardation can be remarkably increased. can be made small As a result, further thinning of the polarizing plate (result, organic EL display device) provided with the retardation layer and the pressure-sensitive adhesive layer can be realized. In this specification, the "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 hardened layer" is a concept including an alignment hardened layer obtained by curing a liquid crystal monomer. In this embodiment, the rod-like liquid crystal compounds are typically aligned in a state aligned in the direction of the slow axis of the retardation layer (homogeneous alignment). The specific example of a liquid crystal compound and the detail of the formation method of a liquid crystal alignment hardening layer are described in Unexamined-Japanese-Patent No. 2006-163343 and Unexamined-Japanese-Patent No. 2006-178389, for example. Descriptions of these publications are incorporated herein by reference.

The thickness of the retardation layer can be typically set to a thickness that can properly function as a λ/4 plate. When the retardation layer is a stretched film of a resin film, the thickness of the retardation layer may be, for example, 10 μm to 60 μm. When the retardation layer is a liquid crystal alignment solidified layer, the thickness of the retardation layer may be, for example, 1 μm to 5 μm.

When the retardation layer has a laminated structure, the retardation layer typically has a two-layer structure of a first liquid crystal alignment fixed layer and a second liquid crystal alignment fixed layer. In this case, either of the first liquid crystal alignment fixed layer or the second liquid crystal alignment fixed layer can function as a λ/2 plate, and the other can function as a lambda/4 plate. Here, the case where the 1st liquid-crystal orientation hardened layer can function as a lambda/2 plate and the 2nd liquid-crystal orientation hardened layer can function as a lambda/4 plate is demonstrated, but these may be reversed. The thickness of the first liquid crystal alignment hardening layer may be adjusted so as to obtain a desired in-plane retardation of the λ/2 plate, and may be, for example, 2.0 μm to 4.0 μm. The thickness of the second liquid crystal alignment hardening layer may be adjusted so as to obtain a desired in-plane retardation of the λ/4 plate, and may be, for example, 1.0 μm to 2.5 μm. The in-plane retardation Re (550) of the first liquid crystal alignment hardened layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, still more preferably 250 nm to 280 nm. As described above, the in-plane retardation Re (550) of the second liquid crystal alignment hardening layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, still more preferably 120 nm to 160 nm. The angle formed by the slow axis of the first liquid crystal alignment solidified layer and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, still more preferably about 15°. The angle formed by the slow axis of the second liquid crystal alignment solidified layer and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, still more preferably about 75°. With such a configuration, it is possible to obtain characteristics close to ideal reverse wavelength dispersion characteristics, and as a result, extremely excellent antireflection characteristics can be realized.

D. The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer

D-1. Outline of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer

The 1st adhesive layer and the 2nd adhesive layer may be comprised from the same adhesive, and may be comprised from each different adhesive. Composition of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer (eg, type of base polymer (polarity, Tg, flexibility), molecular weight), crosslinking structure (eg, type of crosslinking agent, distance between crosslinking points (molecular weight between crosslinking points), crosslinking density) etc., the effect (for example, durability in a high-temperature, high-humidity environment, suppression of discoloration when applied to an organic EL display device) according to the embodiment of the present invention can be made more remarkable.

The thickness of the first pressure-sensitive adhesive layer is preferably 2 μm to 30 μm, more preferably 3 μm to 25 μm, still more preferably 5 μm to 20 μm. The thickness of the second pressure-sensitive adhesive layer is preferably 10 μm to 50 μm, more preferably 15 μm to 40 μm, still more preferably 15 μm to 30 μm. If the thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are within these ranges, durability in a high-temperature, high-humidity environment is excellent due to a synergistic effect with the effect of the configuration of the protective layer and the retardation layer, and furthermore, organic EL display When applied to a device, a polarizing plate provided with a retardation layer and an adhesive layer in which discoloration is remarkably suppressed can be realized.

The solubility of the first pressure-sensitive adhesive layer (actually, the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer) in ethyl acetate at 25 ° C is preferably 2 g / 100 g to 70 g / 100 g, more preferably 10 g / 100 g to It is 60g/100g, More preferably, it is 15g/100g - 60g/100g.

The molar extinction coefficient of the first pressure-sensitive adhesive layer at a wavelength of 380 nm is preferably 400 L/(mol cm) or more, more preferably 500 L/(mol cm) or more, still more preferably 600 L/(mol cm). cm) or more. On the other hand, the molar extinction coefficient is preferably 1500 L/(mol·cm) or less. If the molar extinction coefficient is within this range, the adverse effects of the conductive agent can be reduced, and excellent durability can be realized in a high-temperature, high-humidity environment. A molar extinction coefficient is a value calculated|required by the following formula.

Molar extinction coefficient=A/(c×l)

(Wherein, A represents absorbance, c represents molar concentration (mol/L), and l represents cell thickness (cm))

The gel fraction of the first pressure-sensitive adhesive layer is preferably 60% or more, more preferably 60% to 90%, still more preferably 78% to 90%. If the gel fraction is within this range, foaming and peeling can be suppressed in a high-temperature, high-humidity environment, and deterioration in appearance can be suppressed. The gel fraction is determined by (dry weight after immersion/dry weight before immersion) × 100 when the crosslinked pressure-sensitive adhesive is immersed in a predetermined solvent (eg, ethyl acetate) for 6 days and then dried.

Hereinafter, the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are collectively described as the pressure-sensitive adhesive layer, and the constituent material (pressure-sensitive adhesive composition).

D-2. Constituent materials of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer

D-2-1. base polymer

The pressure-sensitive adhesive layer is typically formed of a pressure-sensitive adhesive composition containing a (meth)acrylic polymer, a urethane polymer, a silicone polymer, or a rubber polymer as a base polymer. When a (meth)acrylic polymer is used as the base polymer, the pressure-sensitive adhesive layer is formed of, for example, a pressure-sensitive adhesive composition containing the (meth)acrylic polymer (A). The (meth)acrylic polymer (A) contains an alkyl (meth)acrylate as a main component.

<(meth)acrylic polymer (A)>

As described above, the (meth)acrylic polymer (A) contains an alkyl (meth)acrylate as a main component. It is preferable that the alkyl (meth)acrylate is 50% by weight or more in terms of improving the adhesiveness of the pressure-sensitive adhesive layer in all the monomer components forming the (meth)acrylic polymer (A), and the alkyl (meth)acrylic acid is It can be arbitrarily set as the remainder of the monomers other than the rate. In addition, (meth)acrylate refers to an acrylate and/or methacrylate.

Examples of the alkyl (meth)acrylate constituting the main skeleton of the (meth)acrylic polymer (A) include straight-chain or branched-chain alkyl groups having 1 to 18 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, an amyl group, a hexyl group, a cyclohexyl group, a heptyl group, a 2-ethylhexyl group, an isooctyl group, a nonyl group, and A sil group, an isodecyl group, a dodecyl group, an isomyristyl group, a lauryl group, a tridecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, etc. are mentioned. Alkyl (meth)acrylates may be used alone or in combination. It is preferable that it is 3-10, and, as for average carbon number of an alkyl group, it is more preferable that it is 3-6.

The (meth)acrylic polymer (A) contains acrylic acid as a monomer component as described above. As described above, the acrylic acid content in the monomer component is preferably 0.1% by weight to 10% by weight, more preferably 0.2% by weight to 8% by weight, still more preferably 0.2% by weight to 6% by weight.

The (meth)acrylic polymer (A) may contain copolymerization monomers such as carboxyl group-containing monomers (a1) and hydroxyl group-containing monomers (a2) other than acrylic acid. Copolymerization monomers can be used alone or in combination.

The carboxyl group-containing monomer (a1) is a compound containing a carboxyl group in its structure and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

The hydroxyl group-containing monomer (a2) is a compound containing a hydroxyl group in its structure and also a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. ) Hydroxyalkyl (meth)acrylates such as acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; (4-hydroxymethylcyclohexyl)-methyl acrylate etc. are mentioned. Among these, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferable from the viewpoint of improving the durability of the pressure-sensitive adhesive layer.

When a hydroxyl group-containing monomer (a2) is used as the monomer component, the content of the hydroxyl group-containing monomer (a2) is usually 0.01% by weight or more in all monomer components forming the (meth)acrylic polymer (A). It is 10 weight% or less, More preferably, it is 0.05 weight% - 3 weight%.

As the monomer component, other copolymerization monomers (a3) may also be used. The other copolymerization monomer (a3) has a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group. By using other copolymerization monomers (a3), the adhesiveness and heat resistance of the pressure-sensitive adhesive layer can be improved. Other copolymerization monomers (a3) can be used alone or in combination.

As the other copolymerization monomer (a3), the adhesiveness of the pressure-sensitive adhesive layer can be improved by using an amino group-containing monomer or an amide group-containing monomer. The amino group-containing monomer is, for example, N,N-dimethylaminoethyl (meth)acrylate or N,N-dimethylaminopropyl (meth)acrylate. Amide group-containing monomers include, for example, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, ) Acrylamide, N-butyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylol-N-propane (meth) acrylamide, aminomethyl (meth) ) Acrylamide-based monomers such as acrylamide, aminoethyl (meth)acrylamide, mercaptomethyl (meth)acrylamide, and mercaptoethyl (meth)acrylamide; N-acryloyl heterocyclic monomers such as N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine; N-vinyl group-containing lactam-based monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam.

In addition to the above-mentioned other copolymerization monomers (a3), for example, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, (meth)acrylic acid (meth)acrylic acid alkoxyalkyl esters such as 3-methoxypropyl, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate; cyclization polymerizable monomers such as 2-(allyloxymethyl)methyl acrylate; epoxy group-containing monomers such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate; sulfonic acid group-containing monomers such as sodium vinyl sulfonate; phosphoric acid group-containing monomers; (meth)acrylic acid esters having alicyclic hydrocarbon groups such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; (meth)acrylic acid esters having aromatic hydrocarbon groups such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene and vinyltoluene; olefins or dienes such as ethylene, propylene, butadiene, isoprene, and isobutylene; vinyl ethers such as vinyl alkyl ether; Vinyl chloride may be used.

The content of the other copolymerizable monomer (a3) in the (meth)acrylic polymer is preferably 20% by weight or less.

The (meth)acrylic polymer is, for example, a copolymer of butyl acrylate, acrylic acid, hydroxybutyl acrylate, hydroxyethyl acrylate, and acryloylmorpholine, a copolymer of butyl acrylate, acrylic acid, and hydroxyethyl acrylate. A copolymer of a copolymer, butyl acrylate and hydroxybutyl acrylate, or a copolymer of butyl acrylate, acrylic acid, hydroxybutyl acrylate, N-vinylpyrrolidone, and phenoxyethyl acrylate may be used.

The weight average molecular weight Mw of the (meth)acrylic polymer (A) is, for example, 200,000 to 3,000,000, preferably 1,000,000 to 2,500,000, more preferably 1,200,000 to 2,500,000. If the weight average molecular weight Mw is within this range, a pressure-sensitive adhesive layer excellent in durability (particularly, heat resistance) can be obtained. When the weight average molecular weight Mw exceeds 3,000,000, a rise in viscosity and/or gelation during polymer polymerization may occur.

D-2-2. Silane coupling agent containing a reactive functional group

The pressure-sensitive adhesive composition may contain a reactive functional group-containing silane coupling agent. In the silane coupling agent containing a reactive functional group, the reactive functional group is typically a functional group other than an acid anhydride group. Examples of functional groups other than acid anhydride groups include epoxy groups, mercapto groups, amino groups, isocyanate groups, isocyanurate groups, vinyl groups, styryl groups, acetoacetyl groups, ureido groups, thiourea groups, (meth)acryl groups, heterocyclic groups and combinations thereof. The silane coupling agent containing a reactive functional group can be used alone or in combination.

When blending the reactive functional group-containing silane coupling agent in the pressure-sensitive adhesive composition, the blending amount of the reactive functional group-containing silane coupling agent is usually 0.001 part by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the (meth)acrylic polymer (A).

D-2-3. cross-linking agent

The pressure-sensitive adhesive composition may contain a crosslinking agent. As the crosslinking agent, an organic type crosslinking agent, a polyfunctional metal chelate or the like can be used. As an organic type crosslinking agent, an isocyanate type crosslinking agent, a peroxide type crosslinking agent, an epoxy type crosslinking agent, and an imine type crosslinking agent are mentioned, for example. A polyfunctional metal chelate is one in which a multivalent metal is bonded covalently or coordinately to an organic compound. When the pressure-sensitive adhesive composition is a radiation curable type, a multifunctional monomer can be used as a crosslinking agent. Crosslinking agents may be used alone or in combination.

When blending a crosslinking agent into the pressure-sensitive adhesive composition, the blending amount of the crosslinking agent is usually 0.01 part by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the (meth)acrylic polymer (A).

When blending an isocyanate-based crosslinking agent in the pressure-sensitive adhesive composition, the blending amount of the isocyanate-based crosslinking agent is usually 0.01 part by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the (meth)acrylic polymer.

D-2-4. challenge

In the embodiment of the present invention, the pressure-sensitive adhesive layer (substantially, the pressure-sensitive adhesive composition) contains a conductive agent as described above. As described above, the conductive agent may be contained in the first pressure sensitive adhesive layer or may be contained in the second pressure sensitive adhesive layer. The conductive agent is preferably contained in the first pressure-sensitive adhesive layer. The conductive agent content in the pressure-sensitive adhesive layer is as described in the above section A.

As described above, the conductive agent is an inorganic cation salt. The inorganic cation salt is specifically an inorganic cation-anion salt. As a cation constituting the cation part of the inorganic cation salt, an alkali metal ion is typically mentioned. As a specific example, lithium ion, sodium ion, and potassium ion are mentioned. Preferably, it is lithium ion. Therefore, a preferable inorganic cation salt is a lithium salt.

Examples of the anion constituting the anionic portion of the inorganic cation salt include Cl ^- , Br ^- , I ^- , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , BF ₄ ^- , PF ₆ ^- , ClO ₄ ^- , NO ₃ ^- , CH ₃ COO ^- , CF ₃ COO ^- , CH ₃ SO ₃ ^- , CF ₃ SO ₃ ^- , (CF ₃ SO ₂ ) ₃ C ^- , AsF ₆ ^- , SbF ₆ ^- , NbF ₆ ^- , TaF ₆ ^- , (CN) ₂ N ^- , C ₄ F ₉ SO ₃ ^- , C ₃ F ₇ COO ^- , (CF ₃ SO ₂ )(CF ₃ CO)N ^- , ^- O ₃ S(CF ₂ ) ₃ SO ₃ ^- and the following general formula (1 ) to (4)

(1): (C _n F _2n+1 SO ₂ ) ₂ N ^- (n is an integer from 1 to 10);

(2): CF ₂ (C _m F _2m SO ₂ ) ₂ N ^- (m is an integer from 1 to 10);

(3): ^- O ₃ S(CF ₂ ) _l SO ₃ ^- (l is an integer from 1 to 10);

(4): (C _p F _2p+1 SO ₂ )N- ⁽ C _q F _2q+1 SO ₂ ), (p, q are integers from 1 to 10),

The anion represented by can be mentioned. Fluorine-containing anions are preferred, and fluorine-containing imide anions are more preferred.

Examples of the fluorine-containing imide anion include imide anions having a perfluoroalkyl group. As a specific example, the above (CF ₃ SO ₂ ) (CF ₃ CO) N ^- and general formulas (1), (2) and (4)

(1): (C _n F _2n+1 SO ₂ ) ₂ N ^- (n is an integer from 1 to 10);

(2): CF ₂ (C _m F _2m SO ₂ ) ₂ N ^- (m is an integer from 1 to 10);

(4): (C _p F _2p+1 SO ₂ )N- ⁽ C _q F _2q+1 SO ₂ ), (p, q are integers from 1 to 10),

The anion represented by can be mentioned. Preferably, it is a (perfluoroalkylsulfonyl)imide represented by the general formula (1) such as (CF ₃ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , and more preferably is a bis(trifluoromethanesulfonyl)imide represented by (CF ₃ SO ₂ ) ₂ N ^- . Therefore, a preferable inorganic cation salt that can be used in the embodiment of the present invention is lithium bis(trifluoromethanesulfonyl)imide.

The conductive agent may further contain an organic cation salt as needed. Bleed-out of an inorganic cation salt can be suppressed by using combining an inorganic cation salt and an organic cation salt.

The organic cation salt is, specifically, an organic cation-anion salt. Examples of the cation constituting the cation portion of the organic cation salt include organic onium formed by substitution with an organic group to form an onium ion. Examples of the onium in the organic onium include nitrogen-containing onium, sulfur-containing onium, and phosphorus-containing onium. Preferably, they are nitrogen-containing onium and sulfur-containing onium. As the nitrogen-containing onium, ammonium cation, piperidinium cation, pyrrolidinium cation, pyridinium cation, cation having a pyrroline skeleton, cation having a pyrrole skeleton, imidazolium cation, tetrahydropyrimidinium cation, dihydropyridinium A midinium cation, a pyrazolium cation, and a pyrazolinium cation are mentioned. Preferably, it is an ammonium cation, a piperidinium cation, and a pyrrolidinium cation, More preferably, it is a pyrrolidinium cation. Examples of the sulfur-containing onium include sulfonium cations. As phosphorus containing onium, a phosphonium cation is mentioned, for example. As an organic group in organic onium, an alkyl group, an alkoxyl group, and an alkenyl group are mentioned, for example. Specific examples of preferable organic oniums include tetraalkylammonium cations, alkylpiperidinium cations, and alkylpyrrolidinium cations. More preferably, it is an ethylmethylpyrrolidinium cation. The anion constituting the anion portion of the organic cation salt is as described for the anion constituting the anion portion of the inorganic cation. Therefore, a preferable organic cation salt that can be used in the embodiment of the present invention is a pyrrolidinium salt, more preferably ethylmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide.

D-2-5. radical generator

The pressure-sensitive adhesive layer (substantially, the pressure-sensitive adhesive composition) may contain a radical generating agent. Examples of the radical generator include those that generate radicals by irradiation with visible light or ultraviolet light having a wavelength shorter than 450 nm. Specific examples include hydroxy ketones, benzyldimethyl ketals, amino ketones, acylphosphine oxides, benzophenones, and triazine derivatives containing a trichloromethyl group. A radical generating agent may be used independently or may be used in combination of 2 or more type. The radical generating agent may be a peroxide-based crosslinking agent. The radical generator may be used in an amount of preferably 0.01 part by weight to 2 parts by weight, more preferably 0.01 part by weight to 1 part by weight, based on 100 parts by weight of the base polymer ((meth)acrylic polymer (A)). . Within this range, adjustment of workability, crosslinking stability, etc. is easy.

D-2-6. additive

The pressure-sensitive adhesive composition may contain a (meth)acrylic oligomer and/or an ionic compound. Moreover, the adhesive composition may contain the additive. Specific examples of additives include powders such as colorants and pigments, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, anti-aging agents, light stabilizers, polymerization inhibitors, inorganic or organic fillers, metal powders, Particulate and thin materials are exemplified. Further, within a controllable range, a redox system in which a reducing agent is added may be employed. The type, number, combination, content, etc. of additives can be appropriately set according to the purpose. The content of the additive is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, still more preferably 1 part by weight or less with respect to 100 parts by weight of the (meth)acrylic polymer (A).

E. Image display device

The polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer described in the above items A to D can be applied to an organic EL display device. Accordingly, an embodiment of the present invention includes an organic EL display device using a polarizing plate having such a retardation layer and an adhesive layer. An organic EL display device according to an embodiment of the present invention includes a polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer described in the above items A to D on the viewing side. The polarizing plate including the retardation layer and the pressure-sensitive adhesive layer is laminated so that the retardation layer is on the organic EL cell side (the polarizing plate is on the viewing side). In one embodiment, the organic EL display device has a curved shape (actually, a curved display screen) and/or can be bent or bent. As described above, the inventors of the present invention, when a polarizing plate provided with a retardation layer and an adhesive layer is applied to an organic EL display device, ammonia (substantially, ammonium ions) generated from the organic EL panel causes the retardation layer and the adhesive layer to Discovered a new problem that the polarizing plate provided with discoloration, and solved the subject by the polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer described in the above items A to D. That is, in the organic EL display device, the effect of the polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer according to the embodiment of the present invention is remarkable.

Example

Hereinafter, the present invention will be specifically described by examples, but the present invention is not limited by these examples. The measurement method of each characteristic is as follows. In addition, unless otherwise specified, "parts" and "%" in Examples and Comparative Examples are based on weight.

(1) Thickness

The thickness of 10 μm or less was measured using an interference film thickness meter (manufactured by Otsuka Electronics, product name “MCPD-3000”). The thickness exceeding 10 μm was measured using a digital micrometer (manufactured by Anritsu Corporation, product name “KC-351C”).

(2) single transmittance and degree of polarization

For the polarizing plates used in Examples and Comparative Examples, single transmittance Ts, parallel transmittance Tp, and orthogonal transmittance Tc measured using a UV-visible spectrophotometer ("LPF-2000" manufactured by Otsuka Electronics Co., Ltd.) were respectively Ts and Tp of the polarizer and Tc. These Ts, Tp, and Tc are Y values measured by a 2-degree field of view (C light source) of JIS Z8701 and corrected for visibility. From the obtained Tp and Tc, the polarization degree P was calculated|required by the following formula.

Polarization degree P (%) = {(Tp-Tc)/(Tp+Tc)} ^1/2 × 100

(3) Permeability

It was measured according to JIS Z 0208. Specifically, the protective layer or retardation layer used in Examples and Comparative Examples (the film constituting the film) was cut out in a circular shape of 10 cm φ to obtain a measurement sample. About this measurement sample, the moisture permeability was measured on test conditions of 40 degreeC and 92%RH using "MOCON" by Hitachi Seisakusho Co., Ltd..

(4) Ammonia decolorization test

10 g of 10% ammonia aqueous solution was placed in a glass bottle (cylindrical shape with a diameter of 30 mm and a depth of 50 mm). At this time, the distance from the liquid level of the aqueous ammonia solution to the inlet (top) of the glass bottle was about 30 mm. A polarizing plate provided with a retardation layer and an adhesive layer obtained in Examples and Comparative Examples was cut out to a size of 15 mm × 15 mm, and used as a measurement sample. The measurement sample was bonded to the edge of the glass bottle mouth through the second pressure-sensitive adhesive layer so as to cover the entire opening of the glass bottle with the measurement sample and prevent steam from leaking through the gap. A glass bottle covered with the measurement sample was heated at 60° C. for 3 hours. ΔTs was calculated from the equation: ΔTs=Ts ₃ -Ts ₀ assuming that the single transmittance of the polarizing plate (substantially, the polarizer) including the retardation layer and the pressure-sensitive adhesive layer before heating was Ts ₀ and the single transmittance after heating was Ts ₃ . In addition, it means that decolorization by ammonia is suppressed, so that (DELTA)Ts is small.

(5) durability

The polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer obtained in Examples and Comparative Examples was cut into a size of 300 mm × 220 mm, and an alkali-free glass plate (manufactured by Corning, trade name "EAGLE XG", thickness) was passed through the second pressure-sensitive adhesive layer using a laminator. 70 μm). Subsequently, an autoclave treatment was performed at 50°C and 0.5 MPa for 15 minutes, and the polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer was completely brought into close contact with the alkali-free glass to obtain a measurement sample. After subjecting this measurement sample to 500-hour treatment (heating test) in an 85 ° C. atmosphere, and further subjecting to 500-hour treatment (humidification test) in an atmosphere of 65 ° C./95% RH, a phase difference layer and an adhesive layer were provided. The appearance between one polarizing plate and the glass was visually evaluated according to the following criteria.

Excellent: Completely no change in appearance such as foaming or peeling

Good: Although there is slight peeling at the end or there is foaming, there is no problem in practical use.

Acceptable: There is peeling or foaming at the end, but no problem in practical use unless it is for a special purpose

Defect: There is significant peeling at the end, and there is a problem in practical use

[Production Example 1: Production of Polarizing Plate]

(Production of polarizer)

As the thermoplastic resin substrate, an amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 µm) having a long shape, water absorption of 0.75%, and Tg of about 75°C was used. Corona treatment was performed on one side of the resin substrate.

Polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetacetyl-modified PVA (manufactured by Nippon Kosei Chemical Co., Ltd., trade name "Gosepima Z410") were mixed in a ratio of 9:1 to 100 parts by weight of a PVA-based resin, iodinated 13 parts by weight of potassium was dissolved in water to prepare a PVA aqueous solution (coating liquid).

The PVA-based resin layer having a thickness of 13 μm was formed by applying the PVA aqueous solution to the corona-treated surface of the resin substrate and drying at 60° C., thereby producing a laminate.

The obtained layered product was uniaxially stretched at the free end by 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different circumferential speeds in an oven at 130°C (air assisted stretching treatment).

Next, the laminate was immersed in an insolubilization bath (boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilization treatment).

Next, a dyeing bath (an aqueous iodine solution obtained by blending iodine and potassium iodide in a weight ratio of 1:7 with respect to 100 parts by weight of water) at a solution temperature of 30 ° C. was added so that the finally obtained polarizing film had a single transmittance (Ts) of 43.0%. It was immersed for 60 seconds while adjusting the concentration (dyeing treatment).

Next, it was immersed in a crosslinking bath (boric acid aqueous solution 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) at a solution temperature of 40°C for 30 seconds (crosslinking treatment).

Thereafter, the laminate is immersed in a boric acid aqueous solution (boric acid concentration: 4.0% by weight, potassium iodide: 5.0% by weight) at a solution temperature of 70°C, while the total draw ratio is increased by 5.5 times in the machine direction (longitudinal direction) between rolls with different circumferential speeds. Uniaxial stretching was performed as much as possible (underwater stretching treatment).

Thereafter, the laminate was immersed in a washing bath (aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 20°C (washing treatment).

Thereafter, while drying in an oven maintained at 90°C, it was brought into contact with a heating roll made of SUS whose surface temperature was maintained at 75°C for about 2 seconds (dry shrinkage treatment). The shrinkage rate in the width direction of the layered product by the drying shrinkage treatment was 5.2%.

In this way, a polarizer having a thickness of 5 μm was formed on the resin substrate.

(Manufacture of polarizer)

An HC-COP film was bonded to the surface of the polarizer of the laminate of the resin substrate/polarizer obtained above with an ultraviolet curable adhesive. Specifically, the coating was applied so that the thickness of the curable adhesive was 1.0 μm, and bonding was performed using a roll machine. Thereafter, UV rays were irradiated from the side of the HC-COP film to cure the adhesive. In addition, the HC-COP film is a film in which an HC layer (thickness of 2 μm) is formed on a cycloolefin-based resin (COP) film (thickness of 25 μm), and the COP film is bonded so as to be on the polarizer side. The moisture permeability of the HC-COP film was 17 g/m 2 24 h.

[Production Example 2: Production of Polarizing Plate]

A polarizing plate P2 having a visual side protective layer (acrylic film)/polarizer was obtained in the same manner as in Production Example 1 except that an acrylic film (thickness: 20 μm) was used instead of the HC-COP film as the visual side protective layer. The moisture permeability of the acrylic film was 146 g/m 2 24h.

[Production Example 3: Production of Polarizing Plate]

Except for using the HC-TAC film instead of the HC-COP film as the visual side protective layer, in the same manner as in Production Example 1, a polarizing plate P3 having a visual side protective layer (HC-TAC film)/polarizer configuration was obtained. In addition, the HC-TAC film is a film in which a hard coating (HC) layer (thickness of 7 μm) is formed on a triacetyl cellulose (TAC) film (thickness of 25 μm), and the TAC film is bonded so as to be on the polarizer side. The moisture permeability of the HC-TAC film was 427 g/m 2 24h.

[Production Example 4: Production of retardation film constituting retardation layer]

(Polymerization of polyester carbonate-based resin)

Polymerization was carried out using a batch polymerization apparatus composed of two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100°C. Bis [9- (2-phenoxycarbonylethyl) fluoren-9-yl] methane 29.60 parts (0.046 mol), isosorbide (ISB) 29.21 parts (0.200 mol), spiroglycol (SPG) 42.28 parts (0.139 mol), 63.77 parts (0.298 mol) of diphenyl carbonate (DPC), and 1.19×10 ⁻² parts (6.78×10 ⁻⁵ mol) of calcium acetate monohydrate as a catalyst were added. After substituting the inside of the reactor with reduced pressure nitrogen, heating was performed with a heat medium, and stirring was started when the internal temperature reached 100°C. The internal temperature reached 220°C 40 minutes after the start of the temperature rise, and while controlling to maintain this temperature, the pressure reduction was started, and after reaching 220°C, it was set to 13.3 kPa in 90 minutes. Phenol vapor produced as a byproduct of the polymerization reaction was directed 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 directed to a condenser at 45° C. for recovery. After nitrogen was introduced into the first reactor to once restore pressure to atmospheric pressure, the oligomerized reaction solution in the first reactor was transferred to the second reactor. Then, the temperature increase and pressure reduction in the 2nd reactor were started, and it set internal temperature to 240 degreeC and pressure 0.2 kPa in 50 minutes. Thereafter, polymerization was allowed to proceed until a predetermined agitation power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor to restore pressure, the resulting polyester carbonate-based resin was extruded into water, and the strands were cut to obtain pellets.

(Production of retardation film)

After vacuum drying the obtained polyester carbonate-based resin (pellet) at 80 ° C. for 5 hours, a single screw extruder (manufactured by Toshiba Kikai Co., Ltd., cylinder set temperature: 250 ° C.), T die (width 200 mm, set temperature: 250 ° C.) ), a cooling roll (set temperature: 120 to 130°C) and a film forming apparatus equipped with a winding machine were used to prepare a long resin film having a thickness of 135 µm. The obtained elongated resin film was stretched in the width direction at a stretching temperature of 133°C and a stretching ratio of 2.8 to obtain phase difference film I having a thickness of 47 µm. Re(550) of the obtained retardation film was 141 nm, Re(450)/Re(550) was 0.82, and the Nz coefficient was 1.12. Moreover, the water vapor transmission rate of the obtained retardation film was 75 g/m<2>*24h.

[Production Example 5: Preparation of base polymer of pressure-sensitive adhesive]

A monomer mixture containing 76.9 parts of butyl acrylate, 18 parts of benzyl acrylate, 5 parts of acrylic acid, and 0.1 part of 4-hydroxybutyl acrylate was added to a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser. did Further, to 100 parts of this monomer mixture, 0.1 part of 2,2'-azobisisobutyronitrile as a polymerization initiator was introduced together with 100 parts of ethyl acetate, and nitrogen gas was introduced with gentle stirring to replace the flask with nitrogen. A polymerization reaction was performed for 8 hours while maintaining the temperature of the liquid inside at around 55°C, and a solution of an acrylic polymer (base polymer A) having a weight average molecular weight (Mw) of 2,000,000 was prepared.

[Production Example 6: Preparation of base polymer of pressure-sensitive adhesive]

Mw250 only acrylic polymer (base polymer B ) was prepared.

[Production Example 7: Preparation of base polymer of pressure-sensitive adhesive]

A solution of Mw1,60 only acrylic polymer (base polymer C) was prepared in the same manner as in Production Example 5 except that a monomer mixture containing 99 parts of butyl acrylate and 1 part of 4-hydroxybutyl acrylate was used.

[Production Example 8: Preparation of base polymer of pressure-sensitive adhesive]

Except for using a monomer mixture containing 89.3 parts of butyl acrylate, 0.2 part of acrylic acid, 0.5 part of 4-hydroxybutyl acrylate, 2 parts of N-vinylpyrrolidone and 8 parts of methyl methacrylate, in the same manner as in Production Example 5, A solution of Mw160 only acrylic polymer (base polymer D) was prepared.

[Production Example 9: Preparation of base polymer of pressure-sensitive adhesive]

A solution of Mw230 only acrylic polymer (base polymer E) was prepared in the same manner as in Production Example 5 except that a monomer mixture containing 94.9 parts of butyl acrylate, 5 parts of acrylic acid, and 0.1 part of hydroxyethyl acrylate was used.

[Production Example 10: Preparation of pressure-sensitive adhesive composition]

With respect to 100 parts each of the base polymers A to E obtained in Production Examples 5 to 9, a radical generator, a crosslinking agent, and a silane coupling agent were blended in the proportions shown in Table 1 to prepare an adhesive composition (adhesive). The names, abbreviations, etc. in Table 1 are as follows.

"BA": butyl acrylate

"AA": acrylic acid

"4HBA": 4-hydroxybutyl acrylate

"HEA": hydroxyethyl acrylate

"ACMO": Acryloylmorpholine

"NVP": N-vinylpyrrolidone

"MMA": methyl methacrylate

"BPO": benzoyl peroxide

"C/L": trimethylolpropane/tolylene diisocyanate adduct (manufactured by Tosoh Corporation, trade name "Coronate L")

"D110N": Trimethylolpropane/xylylenediisocyanate adduct (manufactured by Mitsui Chemicals, trade name "Takenate D110N")

"X-41-1056": alkoxy-containing organopolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd.)

"KBM403": Epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd.)

[Example 1]

A pressure-sensitive adhesive layer having a thickness of 20 μm was formed from the pressure-sensitive adhesive composition A shown in Table 1, and it was set as the first pressure-sensitive adhesive layer. Furthermore, a pressure-sensitive adhesive layer having a thickness of 20 μm was formed from the pressure-sensitive adhesive composition E, and it was set as the second pressure-sensitive adhesive layer. In addition, the conductive agent was blended in the PSA composition A in the ratio shown in Table 2. Retardation film I obtained in Production Example 4 was bonded to the polarizer surface of polarizing plate P1 obtained in Production Example 1 via the first pressure-sensitive adhesive layer, and further, a second pressure-sensitive adhesive layer was formed on the surface of the retardation film. In this way, a polarizing plate having the retardation layer and the pressure-sensitive adhesive layer of this example was produced. The obtained polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer was subjected to the evaluations of (4) and (5) above. The results are shown in Table 2. In Table 2, the gel fractions of the first pressure sensitive adhesive layer and the second pressure sensitive adhesive layer are also shown together.

[Examples 2 to 9, Comparative Examples 1 to 6 and Reference Example 1]

Formation of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer with the formulation, thickness and gel fraction of the conductive agent shown in Table 2, and the phase difference layer with the combination of the polarizing plate, retardation film, first pressure-sensitive adhesive layer and second pressure-sensitive adhesive layer shown in Table 2 And a polarizing plate having a pressure-sensitive adhesive layer was manufactured. The obtained polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer was subjected to the same evaluation as in Example 1. The results are shown in Table 2. In addition, names, abbreviations, etc. in Table 2 are as follows.

"Li-TFSI": Lithium bis(trifluoromethanesulfonyl)imide (manufactured by Mitsubishi Material Denshi Kasei Co., Ltd.)

"AS100": 1-ethyl-3-methylimidazolium bisfluorosulfonylimide (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

[evaluation]

As is clear from Table 2, according to the examples of the present invention, even when exposed to ammonia, the change in single transmittance is small (i.e., there is little discoloration), and the durability is excellent in a high-temperature, high-humidity environment (specifically, the pressure-sensitive adhesive layer A polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer can be obtained. Further, as is clear from Reference Example 1, it was found that the effect of containing a conductive agent and acrylic acid in the pressure-sensitive adhesive layer was an effect obtained in a configuration in which the water vapor transmission rate of the protective layer on the visual side of the polarizing plate was small (however, the visual side of the polarizing plate was It is not denied that a conductive agent and acrylic acid are contained in the pressure-sensitive adhesive layer when the protective layer has a high water vapor transmission rate).

The polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer of the present invention is suitably used as an antireflection circular polarizing plate for an organic EL display device.

10: polarizer
11: polarizer
12: protective layer
13: protective layer
20: first adhesive layer
30: phase difference layer
40: second adhesive layer
100: polarizing plate having a retardation layer and an adhesive layer

Claims (7)

A polarizer and a polarizing plate including a protective layer on at least the viewing side of the polarizer, a retardation layer bonded to the viewing side and the opposite side of the polarizing plate via the first pressure-sensitive adhesive layer, and disposed as an outermost layer on the side opposite to the polarizing plate of the retardation layer. has a second pressure-sensitive adhesive layer,
The first pressure-sensitive adhesive layer or the second pressure-sensitive adhesive layer contains acrylic acid as a monomer component of the base polymer and further contains a conductive agent of an inorganic cation salt,
The content of the conductive agent is 0.4 parts by weight to 12 parts by weight based on 100 parts by weight of the base polymer of the pressure-sensitive adhesive layer.
A polarizing plate provided with a retardation layer and an adhesive layer. The polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer according to claim 1, wherein the acrylic acid content in the monomer component is 0.1% by weight to 10% by weight. The polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer according to claim 1 or 2, wherein the first pressure-sensitive adhesive layer contains acrylic acid as a monomer component of the base polymer and further contains a conductive agent of an inorganic cation salt. The polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer according to any one of claims 1 to 3, wherein the polarizer and the retardation layer are bonded via the first pressure-sensitive adhesive layer. The polarizing plate provided with a retardation layer and an adhesive layer according to any one of claims 1 to 4, wherein the inorganic cation salt is a lithium salt. The polarizing plate provided with the retardation layer and the pressure-sensitive adhesive layer according to any one of claims 1 to 5, wherein the protective layer on the visual side has a water vapor transmission rate of 200 g/m 2 24 h or less. An organic electroluminescent display device comprising a polarizing plate provided with the retardation layer according to any one of claims 1 to 6 and an adhesive layer.

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