JP2020160274A - Polarizing plate set and image display device including the set - Google Patents

Abstract

To provide a polarizing plate set capable of achieving a polarizing plate whose crack is suppressed although each has an irregular shape processing part.SOLUTION: The polarizing plate set comprises a first polarizing plate which is arranged on one side of an image display cell and a second polarizing plate which is arranged on the other side of the image display cell. The first polarizing plate includes a first polarizer and a protective layer which is arranged on at least one side of the first polarizer. The second polarizing plate includes a second polarizer and the protective layer which is arranged on at least one side of the second polarizer. The first polarizer has an absorption axis in a first direction and the second polarizer has the absorption axis in a second direction substantially orthogonal to the first direction. The first polarizing plate and the second polarizing plate have the irregular shape processing part in positions which correspond to each other.SELECTED DRAWING: Figure 1

Description

The present invention relates to a set of polarizing plates and an image display device including the set.

Polarizing plates are widely used in image display devices such as mobile phones and notebook personal computers in order to realize image display and / or enhance the performance of the image display. In recent years, it may be desired to process a polarizing plate to a shape other than a rectangle (deformed processing: for example, formation of a notch or a through hole). However, the deformed portion has a problem that cracks are likely to occur.

Patent No. 4849115 Japanese Unexamined Patent Publication No. 2011-203571

The present invention has been made to solve the above-mentioned conventional problems, and its main purpose is to provide a set of polarizing plates capable of realizing a polarizing plate in which cracks are suppressed even though each has a deformed processed portion. To provide.

The set of polarizing plates of the present invention comprises a first polarizing plate arranged on one side of an image display cell and a second polarizing plate arranged on the other side of the image display cell. The first polarizing plate has a first polarizing element and a protective layer arranged on at least one side of the first polarizing element; the second polarizing plate includes a second polarizing element. It has a protective layer disposed on at least one side of the second polarizing element. The first polarizer has an absorption axis in the first direction, and the second polarizer has an absorption axis in a second direction substantially orthogonal to the first direction. The first polarizing plate and the second polarizing plate have deformed portions at positions corresponding to each other.
In one embodiment, the deformed portion includes a through hole or a machined portion that becomes a recess when viewed in a plan view. In one embodiment, the recess is a V-shaped or U-shaped notch.
In one embodiment, the first direction is substantially parallel to the direction in which the recess extends.
In one embodiment, the first polarizing plate further has an adhesive layer on the side opposite to the image display cell, and the cut portion or the through hole is filled with the adhesive constituting the adhesive layer. Has been done. In one embodiment, the first polarizing plate further has a cover glass on the outside of the pressure-sensitive adhesive layer.
In one embodiment, at least one of the protective layers of the first polarizing plate comprises a cellulosic resin film.
In one embodiment, the second polarizing plate further has a reflective polarizer on the opposite side of the image display cell.
In one embodiment, the first polarizing plate is arranged on the visual side of the image display cell, and the second polarizing plate is arranged on the back side of the image display cell.
According to another aspect of the present invention, an image display device is provided. This image display device includes an image display cell and a set of the above-mentioned polarizing plates, the first polarizing plate is arranged on the visual side of the image display cell, and the second polarizing plate is the image display cell. It is located on the back side.
In one embodiment, the image display device is a liquid crystal display device.

According to the embodiment of the present invention, by forming a set of a first polarizing plate and a second polarizing plate each having a predetermined configuration, cracks in each polarizing plate (particularly, in particular), which was difficult by itself. Cracks) after durability tests such as heat shock tests can be suppressed.

It is a schematic plan view explaining the 1st polarizing plate and the 2nd polarizing plate in the set of the polarizing plate by one Embodiment of this invention. FIG. 2 is a schematic cross-sectional view taken along line II-II of the first polarizing plate and the second polarizing plate in the set of the polarizing plates of FIG. 1, and the respective arrangement positions of the first polarizing plate and the second polarizing plate. It is the schematic sectional drawing which explains corresponding to. FIG. 5 is a schematic cross-sectional view of an image display device including the set of polarizing plates of FIG. It is a schematic plan view explaining the modification of the deformed part of the 1st polarizing plate and the 2nd polarizing plate in the set of the polarizing plate according to the embodiment of this invention. It is a schematic perspective view of an example of a reflective polarizing element that can be used for a second polarizing plate in the set of polarizing plates according to the embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. The drawings are schematically shown for easy viewing, and the ratios of length, width, thickness, etc., angles, etc. in the drawings are different from the actual ones.

A. Schematic of a Set of Polarizing Plates FIG. 1 is a schematic plan view illustrating a first polarizing plate and a second polarizing plate in a set of polarizing plates according to one embodiment of the present invention; FIG. 2 is a schematic plan view of FIG. FIG. 3 is a schematic cross-sectional view taken along line II-II of each of the first and second polarizing plates in the set of polarizing plates; FIG. 3 is a schematic cross-sectional view of an image display device including the set of polarizing plates of FIG. Is. In the illustrated example, the first polarizing plate will be described as the viewing side polarizing plate, and the second polarizing plate will be described as the back side polarizing plate. The set 100 of the polarizing plates in the illustrated example includes a first polarizing plate 10 and a second polarizing plate 20. As shown in FIG. 3, the first polarizing plate 10 is arranged on the visual side of the image display cell 120, and the second polarizing plate 20 is arranged on the back surface side of the image display cell 120. In the illustrated example, the first polarizing plate 10 includes a first polarizing element 11, a protective layer (outer protective layer) 12 arranged on the visible side of the first polarizing element 11, and a first polarizing element 11. It has a protective layer (inner protective layer) 13 arranged on the image display cell side of the above. One of the protective layers 12 and 13 may be omitted depending on the purpose and the like. Similarly, the second polarizing plate 20 is an image of the second polarizing element 21, the protective layer (outer protective layer) 22 arranged on the back side of the second polarizing element 21, and the second polarizing element 21. It has a protective layer (inner protective layer) 23 arranged on the display cell side. One of the protective layers 22 and 23 may be omitted depending on the purpose and the like.

In the embodiment of the present invention, the first polarizing plate 10 has a deformed processing portion 15, and the second polarizing plate 20 has a deformed processed portion 25. In the present specification, the "deformed portion" refers to a portion processed into a special shape different from a general shape (for example, a rectangle or chamfering of a corner). As shown in FIG. 4, typical examples of the deformed portion include a through hole and a cut portion that becomes a recess when viewed in a plan view. Typical examples of the recess include a V-shaped notch and a U-shaped notch. Where cracks are likely to occur in such a deformed portion, according to the embodiment of the present invention, a first polarizing plate having the configuration described in the present specification (typically, a viewing side polarizing plate). And the second polarizing plate (typically, the back side polarizing plate), the cracks of each polarizing plate (particularly the cracks of the deformed portion and / or the heat shock), which were difficult to do by themselves. Cracks) after endurance tests such as tests can be suppressed.

The deformed portions 15 and 25 are provided at positions corresponding to each other of the first polarizing plate and the second polarizing plate. In the present specification, "provided at positions corresponding to each other" means that the deformed portions overlap when the two polarizing plates are overlapped. The deformed portion is provided at an arbitrary appropriate position according to the purpose. Typically, the deformed portion is provided at or near the end of each polarizing plate. With such a configuration, when the set of polarizing plates is applied to an image display device, the influence on the image display can be minimized. For example, as shown in FIG. 4, the deformed portion may be provided at a substantially central portion of the longitudinal end portion of the rectangular polarizing plate, or may be provided at a predetermined position at the longitudinal end portion, and may be polarized. It may be provided at the corner of the plate. In the illustrated example, the case where the deformed portion is provided at the end in the longitudinal direction is shown, but the deformed portion may be provided at the end in the lateral direction. Further, as shown in the lower right of FIG. 4, a plurality of deformed processing portions may be provided. For example, two or more through holes and / or notches may be provided, and as shown in FIG. 4, the through holes and the notches may be provided in combination.

As shown in FIG. 1, the first polarizer 11 has an absorption axis A1 in the _first direction, and the second polarizer 21 absorbs in a second direction substantially orthogonal to the first direction. It has an axis A ₂ . In one embodiment, the first direction is substantially parallel to the direction in which the recess (eg, notch) 15 extends. In one embodiment, the first direction is the longitudinal direction of the rectangular polarizing plate. As used herein, the term "substantially orthogonal" includes the case where the angle formed by the two directions is 90 ° ± 7 °, preferably 90 ° ± 5 °, and more preferably 90 ° ± 3 °. Is. “Substantially parallel” includes the case where the angle formed by the two directions is 0 ° ± 7 °, preferably 0 ° ± 5 °, and more preferably 0 ° ± 3 °. In addition, the term "orthogonal" or "parallel" in the present specification includes the case of "substantially orthogonal" or "substantially parallel". Further, when referring to an angle herein, it includes both clockwise and counterclockwise with respect to the reference direction.

In one embodiment, the first polarizing plate 10 is referred to as an adhesive layer (not shown: hereinafter, for convenience, "first adhesive layer") on the side opposite to the image display cell 120 (visual side in the illustrated example). ) Further. Preferably, the deformed portion 15 is filled with the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer. By filling the deformed portion with the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer, cracks in the first polarizing plate can be remarkably suppressed. When adopting this configuration, the first polarizing plate 10 may further have a cover glass on the outside of the first pressure-sensitive adhesive layer. That is, the cover glass may be attached to the first polarizing plate via the first pressure-sensitive adhesive layer.

In one embodiment, the second polarizing plate 20 further has a reflective polarizer (not shown) on the opposite side (back side in the illustrated example) of the image display cell 120. The reflective polarizer may also serve as the outer protective layer of the second polarizing plate.

Practically, each of the first polarizing plate 10 and the second polarizing plate 20 has an adhesive layer (not shown: hereinafter referred to as "second adhesive layer" for convenience) on the image display cell side. .. The second pressure-sensitive adhesive layer is used to attach the first polarizing plate 10 and the second polarizing plate 20 to the image display cell, respectively.

If necessary, the first polarizing plate 10 and / or the second polarizing plate 20 may be provided with a retardation layer. The type, number, combination, arrangement position, and characteristics of the retardation layer can be appropriately set according to the purpose. For example, the retardation layer may be a λ / 2 plate, a λ / 4 plate, or a laminate thereof. The λ / 2 plate and the λ / 4 plate typically have a refractive index characteristic of nx> ny ≧ nz. The in-plane retardation Re (550) is preferably 180 nm to 320 nm for the λ / 2 plate, and the in-plane retardation Re (550) is preferably 100 nm to 200 nm for the λ / 4 plate. Further, for example, the retardation layer may be a laminate of a negative B plate (nx> ny> nz) and a positive C plate (nz> nx = ny) or a positive B plate (nz> nx> ny). In the present specification, “Re (λ)” is an in-plane phase difference measured with light having a wavelength of λ nm at 23 ° C. For example, "Re (550)" is an in-plane phase difference 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). “Rth (λ)” is a phase difference in the thickness direction measured with light having a wavelength of λ nm at 23 ° C. For example, "Rth (550)" is a 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, where d (nm) is the thickness of the layer (film). "Nx" is the refractive index in the direction in which the in-plane refractive index is maximized (that is, the slow-phase axis direction), and "ny" is the in-plane direction orthogonal to the slow-phase axis (that is, the phase-advance axis direction). Is the refractive index of, and "nz" is the refractive index in the thickness direction.

Hereinafter, the components of the set of polarizing plates will be specifically described. In the first polarizing plate and the second polarizing plate, the first polarizing plate and the second polarizing plate are collectively referred to as a polarizing plate, and the first and second polarizing elements are collectively referred to as a polarizer. Each protective layer will be collectively described as a protective layer. Since a structure well known in the industry can be adopted for the cover glass, detailed description thereof will be omitted.

B. Polarizing plate B-1. Polarizer The polarizer is typically composed of a resin film containing a dichroic substance. As the resin film, any suitable resin film that can be used as a polarizer can be adopted. The resin film is typically a polyvinyl alcohol-based resin (hereinafter, referred to as “PVA-based resin”) film. The resin film may be a single-layer resin film or a laminated body having two or more layers.

Specific examples of the polarizer composed of a single-layer resin film include those obtained by subjecting a PVA-based resin film to a dyeing treatment with iodine and a stretching treatment (typically, uniaxial stretching). The dyeing with iodine is performed, for example, by immersing a PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or while dyeing. Moreover, you may dye after stretching. If necessary, the PVA-based resin film is subjected to a swelling treatment, a cross-linking treatment, a cleaning treatment, a drying treatment and the like. For example, by immersing the PVA-based resin film in water and washing it with water before dyeing, not only can the stains on the surface of the PVA-based film and the blocking inhibitor be washed, but also the PVA-based resin film is swollen to cause uneven dyeing. Etc. can be prevented.

Specific examples of the polarizer obtained by using the laminate include a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a resin base material and the resin. Examples thereof include a polarizer obtained by using a laminate with a PVA-based resin layer coated and formed on a base material. The polarizer obtained by using the laminate of the resin base material and the PVA-based resin layer coated and formed on the resin base material is, for example, a resin base material obtained by applying a PVA-based resin solution to the resin base material and drying it. It is produced by forming a PVA-based resin layer on the PVA-based resin layer to obtain a laminate of a resin base material and a PVA-based resin layer; stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. obtain. In the present embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Further, stretching may further include, if necessary, stretching the laminate in the air at a high temperature (eg, 95 ° C. or higher) prior to stretching in boric acid aqueous solution. The obtained resin base material / polarizer laminate 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 off from the resin base material / polarizer laminate. Then, an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface. Details of the method for producing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580. The entire description of the publication is incorporated herein by reference.

The thickness of the polarizer is preferably 25 μm or less, more preferably 1 μm to 12 μm, further preferably 3 μm to 12 μm, and particularly preferably 3 μm to 8 μm. When the thickness of the polarizer is in such a range, curling during heating can be satisfactorily suppressed, and good appearance durability during heating can be obtained.

The polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The simple substance transmittance of the polarizer is 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, and further preferably 99.9% or more.

B-2. Protective layer The protective layer is formed of any suitable film that can be used as a protective layer for the 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. , Polystyrene-based, polycarbonate-based, polyolefin-based, (meth) acrylic-based, acetate-based transparent resins and the like. Further, thermosetting resins such as (meth) acrylic, urethane, (meth) acrylic urethane, epoxy, and silicone, or ultraviolet curable resins can also be mentioned. In addition to this, for example, glassy polymers such as siloxane-based polymers can also be mentioned. Further, the polymer film described in JP-A-2001-343529 (WO01 / 37007) can also be used. As the material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. Can be used, and examples thereof include a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. The polymer film can be, for example, an extruded product of the above resin composition.

Is at least one of the outer protective layer 12 and the inner protective layer 13 of the first polarizing plate, preferably, the moisture permeability is preferably 100g ^/ m 2 · 24h or more, more preferably 200g ^/ m 2 · 24h~500g a / ^m 2 · 24h. Generally, it is said that the protective layer of the polarizing plate is preferably made of a material having a low moisture permeability in order to suppress a decrease in the degree of polarization in a humid environment. However, it was found that cracks are likely to occur after the heat shock test with a material having low moisture permeability. Furthermore, when the first polarizing plate and the second polarizing plate described in the present specification are used as a set, the present inventors can make at least one of the protective layers of the first polarizing plate a material having high moisture permeability. It was discovered that the decrease in polarization degree in a humid environment and the cracks after the heat shock test can be suppressed in a well-balanced manner. Such an effect is a finding obtained only when a combination of various polarizing plates is applied to an image display device by trial and error, and is an unexpectedly excellent effect. More specifically, at least one of the protective layers in the first polarizing plate is composed of a cellulosic resin film (typically, a TAC film). By using the cellulosic resin film, the first pressure-sensitive adhesive layer, and the cover glass in combination, it is possible to suppress a decrease in the degree of polarization in a humid environment and cracks after a heat shock test in a particularly well-balanced manner.

When the first pressure-sensitive adhesive layer is provided, the outer protective layer 12 of the first polarizing plate has a breaking elongation at 25 ° C. of preferably 2 mm or more, more preferably 50 mm or more. The breaking elongation can be, for example, 70 mm or less. If the breaking elongation of the outer protective layer 12 is within such a range when the first pressure-sensitive adhesive layer is provided, the relationship between the storage elastic modulus of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is optimized. Cracks in the outer protective layer 12 are remarkably prevented by the synergistic effect of the effect (described later) and the effect of setting the polarizing plate. The elongation at break can be measured according to JIS K7113.

The outer protective layer (particularly, the outer protective layer 12 of the first polarizing plate) may be subjected to surface treatment such as hard coating treatment, antireflection treatment, anti-sticking treatment, anti-glare treatment, etc., if necessary. ..

The inner protective layer is preferably optically isotropic. In the present 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. Say.

Any suitable thickness can be adopted as the thickness of the protective layer. The thickness of the protective layer is, for example, 15 μm to 45 μm, preferably 20 μm to 40 μm. When the surface treatment is applied, the thickness of the protective layer is the thickness including the thickness of the surface treatment layer.

C. First Adhesive Layer The first adhesive layer is typically used to fill the deformed portion of the first polarizing plate. The first adhesive layer, as long as the storage modulus G _{1 'at} -40 ℃ the desired range described later, may be configured in any suitable adhesive. The first pressure-sensitive adhesive layer may be typically composed of a rubber-based pressure-sensitive adhesive (rubber-based pressure-sensitive adhesive composition). The rubber-based pressure-sensitive adhesive composition may typically include a butadiene polymer and / or a polyisoprene polymer (or a modified product thereof) and a photopolymerization initiator. The rubber-based pressure-sensitive adhesive composition includes polystyrene, polyurethane (for example, one made from isophorone diisocyanate), polyurethane acrylate, polyisoprene-based acrylate or esterified product thereof, terpene-based hydrogenated resin, and reactive acrylic-based monomer (for example, 2). -Hydroxybutyl methacrylate, 4-hydroxyethyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, isobornyl acrylate), reactive methacrylic monomer (for example, dicyclopentenyloxyethyl methacrylate) and the like may be further contained. The rubber-based pressure-sensitive adhesive composition may preferably further contain a silane coupling agent. Examples of the silane coupling agent include epoxy group-containing silane coupling agents. Further, the rubber-based pressure-sensitive adhesive composition preferably does not contain a hydrocarbon component (for example, heptane). The thickness of the first pressure-sensitive adhesive layer can be, for example, 10 μm to 50 μm.

First adhesive storage modulus at -40 ℃ of layer _{G 1} 'is preferably is at 5.0 × ¹⁰ 6 (Pa) or more, more preferably 1.0 × ¹⁰ 7 (Pa) or more, further preferably 1.0 × ¹⁰ 8 (Pa) or more, particularly preferably 1.5 × ¹⁰ 8 (Pa) or more. Storage modulus _{G 1} 'may be, for example, 5.0 × ¹⁰ 9 (Pa) or less. Storage modulus G _{1 'is} thus increased (hard, first adhesive layer), and the ratio G _1' by the / G 2 _'satisfies the relationship as described below, cracks in each of the polarizing plate Can be suppressed even better.

D. Second Adhesive Layer The second adhesive layer is typically used to attach the first polarizing plate and the second polarizing plate to the image display cell, respectively. The second pressure-sensitive adhesive layer may be typically composed of an acrylic pressure-sensitive adhesive (acrylic pressure-sensitive adhesive composition). The acrylic pressure-sensitive adhesive composition typically contains a (meth) acrylic polymer as a main component. The (meth) acrylic polymer can be contained in the pressure-sensitive adhesive composition in a proportion of, for example, 50% by weight or more, preferably 70% by weight or more, and more preferably 90% by weight or more in the solid content of the pressure-sensitive adhesive composition. The (meth) acrylic polymer contains an alkyl (meth) acrylate as a main component as a monomer unit. In addition, (meth) acrylate means acrylate and / or methacrylate. Examples of the alkyl group of the alkyl (meth) acrylate include a linear or branched alkyl group having 1 to 18 carbon atoms. The average number of carbon atoms of the alkyl group is preferably 3 to 9. Examples of the monomer constituting the (meth) acrylic polymer include a carboxyl group-containing monomer, a hydroxyl group-containing monomer, an amide group-containing monomer, an aromatic ring-containing (meth) acrylate, and the like, in addition to the alkyl (meth) acrylate. The acrylic pressure-sensitive adhesive composition may preferably contain a silane coupling agent and / or a cross-linking agent. Examples of the silane coupling agent include epoxy group-containing silane coupling agents. Examples of the cross-linking agent include isocyanate-based cross-linking agents and peroxide-based cross-linking agents. The thickness of the second pressure-sensitive adhesive layer can be, for example, 10 μm to 50 μm. Details of the second pressure-sensitive adhesive layer or the acrylic pressure-sensitive adhesive composition are described in, for example, JP-A-2016-190996, and the description of the publication is incorporated herein by reference.

Second storage modulus _{G 2} at -40 ℃ of the adhesive layer 'is preferably 1.0 × ¹⁰ 5 (Pa) or more, more preferably 1.0 × ¹⁰ 7 (Pa) or more, further preferably 1.0 × ¹⁰ 8 (Pa) or more, particularly preferably 1.0 × ¹⁰ 8 (Pa) or more. Storage modulus _{G 2} 'may be, for example, 1.0 × ¹⁰ 9 (Pa) or less. _'With such a range, the ratio G _1' described later storage modulus G ₂ is easily set to a desired value / G 2 _'.

First ratio _{G 1} of the storage modulus at -40 ℃ of the adhesive layer 120 _{G 1} and 'the storage modulus _{G 2} at -40 ℃ second adhesive layer''/ _{G 2'} is preferably 1 It is more than that, more preferably 3 or more, and further preferably 20 or more. If the ratio G _{1 '/} G 2' is 1 or more, by configuring the set of predetermined polarization plate, cracks in each of the polarizing plates (especially crack after endurance tests such as heat shock test) good Can be suppressed. On the other hand, the ratio _{G 1} '/ _{G 2'} may be, for example, 300 or less. More details are as follows. If the storage elastic modulus of the first pressure-sensitive adhesive layer is low (soft), the contraction movement of the polarizer cannot be suppressed, and the protective layer (outer protective layer 12) on the first pressure-sensitive adhesive layer side cracks. May occur. By increasing the storage elastic modulus of the first pressure-sensitive adhesive layer (hardening it, resulting in G ₁ '/ G ₂ '> 1), the dimensional change of the polarizer is suppressed and the outer protective layer is cracked. Can be suppressed. Furthermore, cracks in the second polarizing plate can also be suppressed. In another embodiment, the ratio _{G 1} '/ _{G 2'} may be about 1-2. By reducing the difference in storage elastic modulus between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, it is possible to suppress the occurrence of strain by making the same movement up and down with respect to the contraction of the polarizer.

E. Reflective polarizer The reflective polarizer has a function of transmitting polarized light in a specific polarized state (polarization direction) and reflecting light in other polarized states. The reflective polarizer may be a linearly polarized light separated type or a circularly polarized light separated type. Hereinafter, as an example, a linearly polarized light separation type reflective polarizer will be described. Examples of the circularly polarized light separation type reflective polarizer include a laminate of a film on which a cholesteric liquid crystal is immobilized and a λ / 4 plate.

FIG. 5 is a schematic perspective view of an example of a reflective polarizer. The reflective polarizer is a multi-layer laminated body in which a layer A having birefringence and a layer B having substantially no birefringence are alternately laminated. For example, the total number of layers of such a multi-layer laminate can be 50-1000. In the illustrated example, the refractive index nx in the x-axis direction of the A layer is larger than the refractive index ny in the y-axis direction, and the refractive index nx in the x-axis direction of the B layer and the refractive index ny in the y-axis direction are substantially the same. is there. Therefore, the difference in refractive index between the A layer and the B layer is large in the x-axis direction and substantially zero in the y-axis direction. As a result, the x-axis direction becomes the reflection axis, and the y-axis direction becomes the transmission axis. The difference in refractive index between the A layer and the B layer in the x-axis direction is preferably 0.2 to 0.3. The x-axis direction corresponds to the stretching direction of the reflective polarizer in the method for manufacturing the reflective polarizer.

The layer A is preferably composed of a material that exhibits birefringence by stretching. Representative examples of such materials include polyester naphthalenedicarboxylic acid (eg, polyethylene naphthalate), polycarbonate and acrylic resins (eg, polymethylmethacrylate). Polyethylene naphthalate is preferred. The B layer is preferably composed of a material that does not substantially exhibit birefringence even when stretched. A typical example of such a material is a copolyester of naphthalenedicarboxylic acid and terephthalic acid.

The reflective polarizer has a second polarization direction that transmits light having a first polarization direction (for example, p-wave) at the interface between the A layer and the B layer and is orthogonal to the first polarization direction. Reflects light (eg, s-wave). At the interface between the A layer and the B layer, the reflected light is partially transmitted as light having a first polarization direction and partially reflected as light having a second polarization direction. By repeating such reflection and transmission many times inside the reflective polarizer, the efficiency of light utilization can be improved.

In one embodiment, the reflective polarizer may include a reflective layer R as the outermost layer on the wavelength conversion layer 10 side, as shown in FIG. By providing the reflective layer R, it is possible to further utilize the light that has returned to the outermost side of the reflective polarizer without being finally utilized, so that the efficiency of light utilization can be further improved. The reflective layer R typically exhibits a reflective function due to the multilayer structure of the polyester resin layer.

The overall thickness of the reflective polarizer can be appropriately set according to the purpose, the total number of layers contained in the reflective polarizer, and the like. The overall thickness of the reflective polarizer is preferably 10 μm to 150 μm.

As the reflective polarizer, for example, those described in JP-A-9-507308 can be used. As the reflective polarizer, a commercially available product may be used as it is, or the commercially available product may be used after secondary processing (for example, stretching). Examples of commercially available products include the product name DBEF manufactured by 3M and the product name APF manufactured by 3M.

F. Image Display Device The set of polarizing plates according to the embodiment of the present invention can be suitably applied to the image display device as described above. Therefore, image display devices are also included in the embodiments of the present invention. The image display device includes an image display cell and a set of polarizing plates. The set of polarizing plates is a set of polarizing plates according to the embodiment of the present invention according to the above items A to E. As shown in FIG. 3, the image display device 200 includes an image display cell 120, a first polarizing plate 10 arranged on the visual side of the image display cell 120, and a second polarizing plate 10 arranged on the back side of the image display cell 120. It has 2 polarizing plates 20 and 2.

Examples of the image display device include a liquid crystal display device, an organic electroluminescence (EL) display device, and a quantum dot display device. A liquid crystal display device is preferable. This is because the effect of setting the polarizing plate is remarkable.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The evaluation items in the examples are as follows.

(1) Crack The first polarizing plate of the set of polarizing plates obtained in Examples and Comparative Examples is passed through a second pressure-sensitive adhesive layer on one side of non-alkali glass (thickness 0.7 mm) manufactured by Matsunami Glass Co., Ltd. It was pasted on the surface of. Further, the second polarizing plate was attached to the other surface via the second pressure-sensitive adhesive layer to prepare a test sample. This test sample was subjected to a 200 cycle heat cycle (heat shock) test at −40 ° C. to 85 ° C. After the test, the state of crack occurrence was evaluated by a transmitted light inspection according to the following criteria. The transmitted light inspection was performed so that the second polarizing plate was placed on the planar light source.
◯: Light leakage is not visible (no cracks have occurred)
X: Light leakage can be visually recognized (cracks that cause light leakage have occurred)

<Example 1>
A film (thickness 12 μm) obtained by containing iodine in a long polyvinyl alcohol (PVA) -based resin film as a polarizer (which serves as the first polarizer) and uniaxially stretching it in the longitudinal direction (MD direction). Was used. A normal pressure-sensitive adhesive layer (thickness 5 μm) is formed on both sides of the polarizer, and a long HC-TAC film serving as an outer protective layer and a long shape serving as an inner protective layer are formed through the pressure-sensitive adhesive layer. Acrylic resin films (thickness 20 μm) were laminated so as to be aligned with each other in the longitudinal direction. The HC-TAC film is a film in which a hard coat (HC) layer (thickness 2 μm) is formed on a triacetyl cellulose (TAC) film (thickness 25 μm), and the TAC film is attached so as to be on the polarizer side. I matched it. Further, a second pressure-sensitive adhesive layer (thickness 20 μm) is formed on the surface of the inner protective layer, and a separator is attached to the pressure-sensitive adhesive having the structure of an outer protective layer / a polarizing element / an inner protective layer / a second pressure-sensitive adhesive layer. A polarizing plate with an agent layer was obtained. The second pressure-sensitive adhesive layer was prepared according to [0121] and [0124] of JP2016-190996A. Second storage modulus _{G 2} at -40 ℃ of the adhesive layer 'was 5.0 × ¹⁰ 6 (Pa). The obtained polarizing plate with an adhesive layer is punched into a shape similar to that shown in FIG. 1 (rectangular shape having an approximate size of 142.0 mm × 66.8 mm, a shape having no recess), and the peripheral portion is cut by end milling and the recess is formed. A (U-shaped notch) was formed and used as the first polarizing plate. The absorption axis direction of the first polarizer in the first polarizing plate was the longitudinal direction (the direction in which the U-shaped notch extends). Further, a first pressure-sensitive adhesive layer was formed on the outer protective layer. The first pressure-sensitive adhesive layer was prepared according to [0053] of JP2016-103030A. First storage modulus _{G 1} in -40 ℃ of the adhesive layer 'was 1.7 × ¹⁰ 8 (Pa). The U-shaped notch in the first polarizing plate was filled with the first pressure-sensitive adhesive layer. Further, a cover glass manufactured by Matsunami Glass Co., Ltd. was attached to the first polarizing plate via the first pressure-sensitive adhesive layer.

A polarizing plate having a structure of an outer protective layer / a second polarizer / an inner protective layer in the same manner as above except that a normal TAC film (thickness 25 μm) is used instead of the HC-TAC film as the outer protective layer. Got A second pressure-sensitive adhesive layer is formed on the surface of the inner protective layer of the polarizing plate in the same manner as described above, and has a shape similar to that of FIG. 1 (approximately size 142.0 mm × 66.8 mm, rectangular shape, no recessed portion). After punching into the shape) and attaching a reflective polarizer to the surface of the outer protective layer via a normal adhesive layer (thickness 5 μm), the peripheral edge is cut by end milling and a recess (U-shaped notch) is formed. Then, it was used as a second polarizing plate. The absorption axis direction of the second polarizer in the second polarizing plate was the lateral direction.
As described above, a set of polarizing plates including a first polarizing plate and a second polarizing plate was obtained. The obtained set of polarizing plates was subjected to the evaluation of (1) above. The results are shown in Table 1.

<Example 2>
A first polarizing plate was produced in the same manner as in Example 1 except that a cycloolefin resin film (thickness 13 μm) was used instead of the acrylic resin film as the inner protective layer. Further, a second polarizing plate was produced in the same manner as in Example 1 except that the thickness of the inner protective layer (acrylic resin film) was 13 μm. These first polarizing plates and the second polarizing plates were combined to form a set of polarizing plates. The obtained set of polarizing plates was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 3>
The same polarizing plate as in Example 2 was used as the first polarizing plate. Moreover, the second polarizing plate was produced as follows.

As the thermoplastic resin base material, an amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a long shape and a Tg of about 75 ° C. was used. One side of the resin base material was corona-treated.
100 weight of PVA-based resin in which polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosefimer Z410") are mixed at a ratio of 9: 1. 13 parts by weight of potassium iodide was added to the part to prepare a PVA aqueous solution (coating liquid).
A PVA-based resin layer having a thickness of 13 μm was formed by applying the above PVA aqueous solution to the corona-treated surface of the resin base material and drying at 60 ° C. to prepare a laminate.
The obtained laminate was uniaxially stretched at the free end 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130 ° C. (aerial auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 40 ° C. (an aqueous boric acid solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Next, the finally obtained polarizing film was placed in a dyeing bath having a liquid temperature of 30 ° C. (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1: 7 with respect to 100 parts by weight of water). Immersion was carried out for 60 seconds while adjusting the concentration so that the simple substance transmittance (Ts) was 43% (dyeing treatment).
Next, it was immersed in a cross-linked bath at a liquid temperature of 40 ° C. (an aqueous boric acid 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) for 30 seconds. (Crossing treatment).
Then, while immersing the laminate in a boric acid aqueous solution (boric acid concentration 4.0% by weight, potassium iodide 5.0% by weight) at a liquid temperature of 70 ° C., the rolls having different peripheral speeds are in the longitudinal direction (longitudinal direction). ) Was uniaxially stretched so that the total stretching ratio was 5.5 times (underwater stretching treatment).
Then, the laminate was immersed in a washing bath at a liquid temperature of 20 ° C. (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
Then, 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 (dry shrinkage treatment). The shrinkage rate in the width direction of the laminated body by the dry shrinkage treatment was 2%.
In this way, a polarizer having a thickness of 5.0 μm was formed on the resin substrate.
After the reflective polarizing element is attached to the surface of the polarizer of the laminate of the resin base material / polarizer via a normal pressure-sensitive adhesive layer, the resin base material is peeled off, and an acrylic resin film (thickness 20 μm) is applied to the peeled surface. ) Was laminated to obtain a second polarizing plate having a structure of a reflective polarizer / a second polarizer / an inner protective layer.

These first polarizing plates and the second polarizing plates were combined to form a set of polarizing plates. The obtained set of polarizing plates was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 4>
A resin base material / polarizer laminate was produced in the same manner as in the second polarizer of Example 3. An HC-cycloolefin resin film (HC thickness 2 μm, resin film thickness 25 μm) is attached to the polarizing element surface of the laminate via a normal pressure-sensitive adhesive layer, the resin base material is peeled off, and cyclo is applied to the peeled surface. An olefin resin film (thickness 13 μm) was laminated to obtain a first polarizing plate having a structure of an outer protective layer / a first polarizer / an inner protective layer. Further, as the second polarizing plate, the same one as in Example 3 was used. These first polarizing plates and the second polarizing plates were combined to form a set of polarizing plates. The obtained set of polarizing plates was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 5>
Same as in Example 1 except that the absorption axis direction of the first polarizing element is set to the short side and a cycloolefin resin film (thickness 13 μm) is used instead of the acrylic resin film as the inner protective layer. The first polarizing plate was produced. Further, the same as in Example 3 except that the absorption axis direction of the second polarizer is the longitudinal direction and a TAC film (thickness 20 μm) is used instead of the acrylic resin film as the inner protective layer. A second polarizing plate was produced. These first polarizing plates and the second polarizing plates were combined to form a set of polarizing plates. The obtained set of polarizing plates was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 6>
The first polarizing plate was produced in the same manner as in Example 4 except that the absorption axis direction of the first polarizer was set to the lateral direction. Further, as the second polarizing plate, the same one as in Example 5 was used. These first polarizing plates and the second polarizing plates were combined to form a set of polarizing plates. The obtained set of polarizing plates was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 7>
A first polarizing plate was produced in the same manner as in Example 6 except that an HC-TAC film was used instead of the HC-cycloolefin resin film as the outer protective layer and the inner protective layer was not provided. .. Further, as the second polarizing plate, the same one as in Example 5 was used. These first polarizing plates and the second polarizing plates were combined to form a set of polarizing plates. The obtained set of polarizing plates was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative example 1>
A first polarizing plate was produced in the same manner as in Example 4 except that the first pressure-sensitive adhesive layer was not formed. Further, as the second polarizing plate, the same one as in Example 3 was used. These first polarizing plates and the second polarizing plates were combined to form a set of polarizing plates. The obtained set of polarizing plates was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative example 2>
The first polarizing plate was produced in the same manner as in Example 4 except that the absorption axis direction of the first polarizer was set to the lateral direction. Further, a second polarizing plate was produced in the same manner as in Example 3 except that the absorption axis direction of the second polarizer was set to the longitudinal direction. These first polarizing plates and the second polarizing plates were combined to form a set of polarizing plates. The obtained set of polarizing plates was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative example 3>
A first polarizing plate was produced in the same manner as in Comparative Example 1 except that the absorption axis direction of the first polarizer was set to the lateral direction. Further, as the second polarizing plate, the same one as in Example 5 was used. These first polarizing plates and the second polarizing plates were combined to form a set of polarizing plates. The obtained set of polarizing plates was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

The set of polarizing plates of the present invention is suitably used for an image display device, and is particularly suitable for an image display device having a deformed processing portion typified by an automobile instrument panel, a smartphone, a tablet PC or a smart watch. Can be used.

10 First polarizing plate 11 First polarizing element 12 Outer protective layer 13 Inner protective layer 15 Deformed part 20 Second polarizing plate 21 Second polarizing element 22 Outer protective layer 23 Inner protective layer 25 Deformed part 100 Polarized light Board set 120 Image display cell 200 Image display device

Claims (11)

A set of polarizing plates including a first polarizing plate arranged on one side of an image display cell and a second polarizing plate arranged on the other side of the image display cell.
The first polarizing plate has a first polarizing element and a protective layer arranged on at least one side of the first polarizing element.
The second polarizing plate has a second polarizing element and a protective layer arranged on at least one side of the second polarizing element.
The first polarizer has an absorption axis in the first direction, and the second polarizer has an absorption axis in a second direction that is substantially orthogonal to the first direction.
The first polarizing plate and the second polarizing plate have deformed portions at positions corresponding to each other.
A set of polarizing plates. The set of polarizing plates according to claim 1, wherein the deformed portion includes a through hole or a cutting portion that becomes a recess when viewed in a plan view. The set of polarizing plates according to claim 2, wherein the recess is a V-shaped notch or a U-shaped notch. The set of polarizing plates according to claim 2 or 3, wherein the first direction is a direction substantially parallel to the direction in which the recess extends. Any of claims 1 to 4, wherein the first polarizing plate further has an adhesive layer on the side opposite to the image display cell, and the deformed portion is filled with the adhesive constituting the adhesive layer. A set of polarizing plates described in Crab. The set of polarizing plates according to claim 5, wherein the first polarizing plate further has a cover glass on the outside of the pressure-sensitive adhesive layer. The set of polarizing plates according to any one of claims 1 to 6, wherein at least one of the protective layers of the first polarizing plate contains a cellulosic resin film. The set of polarizing plates according to any one of claims 1 to 7, wherein the second polarizing plate further has a reflective polarizing element on the opposite side of the image display cell. The polarizing plate according to any one of claims 1 to 8, wherein the first polarizing plate is arranged on the visual side of the image display cell, and the second polarizing plate is arranged on the back side of the image display cell. Set of. The image display cell and the set of polarizing plates according to any one of claims 1 to 9 are included, the first polarizing plate is arranged on the visual side of the image display cell, and the second polarizing plate is the image. An image display device located on the back side of the display cell. The image display device according to claim 10, which is a liquid crystal display device.

Images