KR20230169171A - Polarizer with phase contrast layer - Google Patents

Abstract

The present invention provides a polarizing plate with a retardation layer in which the occurrence of cracks during bending in a low-temperature environment is suppressed. The polarizing plate with a retardation layer of the present invention includes a protective layer, a polarizer, a retardation layer, and an adhesive layer in this order, the total thickness from the protective layer to the retardation layer is 80 μm or less, and the adhesive layer has a temperature of -30°C. The storage modulus (G' _-30 ) is 250 kPa or less.

Description

Polarizer with phase contrast layer

The present invention relates to a polarizing plate with a retardation layer.

In recent years, image display devices represented by liquid crystal displays and organic EL displays have been rapidly spreading. Polarizing plates and retardation plates are typically used in image display devices. In practical terms, a polarizing plate with a retardation layer that integrates a polarizing plate and a retardation plate is widely used (for example, patent document 1). In recent years, folding type image display devices, such as smartphones, have been released, and bending resistance is required for polarizing plates with a retardation layer used in such image display devices. However, conventional polarizing plates with a retardation layer have problems such as insufficient bending resistance under harsh environments and cracks occurring when folded.

Japanese Patent Publication No. 2002-372622 Japanese Patent Publication No. 3325560

The present invention was made to solve the above-described conventional problems, and its main purpose is to provide a polarizing plate with a retardation layer in which the occurrence of cracks is suppressed in a low-temperature environment.

The polarizing plate with a retardation layer of the present invention includes a protective layer, a polarizer, a retardation layer, and an adhesive layer in this order, the total thickness from the protective layer to the retardation layer is 80 μm or less, and the adhesive layer has a temperature of -30°C. The storage modulus (G' _-30 ) at is 250 kPa or less.

In one embodiment, the storage modulus of the adhesive layer at -30°C (G' _-30 ) and the storage modulus of the adhesive layer at 25°C ( _G'25 ) satisfy the following equation (1).

1≤G' _-30 /G' ₂₅ ≤10… (One)

In one embodiment, the storage modulus (G'- ₃₀ ) of the pressure-sensitive adhesive layer at -30°C is 200 kPa or less.

In one embodiment, the adhesive layer is made of an acrylic adhesive containing an acrylic base polymer.

In one embodiment, the acrylic base polymer contains 1 part by weight to 40 parts by weight of (meth)acrylic acid C _10-20 chain alkyl ester based on a total of 100 parts by weight of the monomer components.

In one embodiment, the acrylic base polymer is the (meth)acrylic acid C _10-20 chain alkyl ester and includes lauryl acrylate.

In one embodiment, the acrylic base polymer contains 5 weight of a monomer containing at least one polar group selected from a monomer containing a nitrogen atom ring, a monomer containing a hydroxy group, and a monomer containing a carboxy group, based on a total of 100 parts by weight of the monomer component. Contains ~30 parts by weight.

In one embodiment, the acrylic base polymer contains 10 parts by weight or less of a hydroxy group-containing monomer based on a total of 100 parts by weight of the monomer components.

In one embodiment, the total thickness from the protective layer to the retardation layer is 60 μm or less.

In one embodiment, the thickness of the polarizer is 10 μm or less.

In one embodiment, the thickness of the protective layer is 45 μm or less.

In one embodiment, the retardation layer has a laminated structure of a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer, the first liquid crystal alignment solidification layer has a Re(550) of 200 nm to 300 nm, and its ground surface The angle between the axis and the absorption axis of the polarizer is 10° to 20°, the Re (550) of the second liquid crystal alignment solidification layer is 100 nm to 190 nm, and the angle between its slow axis and the absorption axis of the polarizer is 70°. °~80°.

In one embodiment, the retardation layer is a single layer of a liquid crystal alignment solidification layer, the Re(550) of the retardation layer is 100 nm to 180 nm, and Re (450) < Re (550) < Re (650). The relationship is satisfied, and the angle between its slow axis and the absorption axis of the polarizer is 35° to 55°. Additionally, in one embodiment, the retardation layer further includes another retardation layer, and the other retardation layer exhibits a refractive index characteristic of nz>nx=ny.

According to an embodiment of the present invention, a polarizing plate with a retardation layer includes a protective layer, a polarizer, a retardation layer, and an adhesive layer in this order, the total thickness from the protective layer to the retardation layer is 80 μm or less, and the adhesive When the storage modulus (G' _-30 ) of the layer at -30°C is 250 kPa or less, it is possible to realize a polarizing plate with a retardation layer in which the occurrence of cracks during bending in a low-temperature environment is suppressed.

1 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention.
Figure 2 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to another embodiment of the present invention.

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

(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 where the in-plane refractive index is maximum (i.e., slow axis direction), 'ny' is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., fast axis direction), and 'nz' is It is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

'Re(λ)' is the in-plane phase difference measured with light with a wavelength of λ nm at 23°C. For example, 'Re(550)' is the in-plane phase difference measured with light with a wavelength of 550 nm at 23°C. Re(λ) can be obtained by the formula: Re(λ)=(nx-ny)×d, when the thickness of the layer (film) is d (nm).

(3) Phase difference in the thickness direction (Rth)

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

(4) Nz coefficient

The Nz coefficient can be obtained by Nz=Rth/Re.

(5) angle

When an angle is mentioned herein, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Therefore, for example, '45°' means ±45°.

A. Overall composition of polarizer with phase contrast layer

The polarizing plate with a retardation layer of the present invention includes a protective layer, a polarizer, a retardation layer, and an adhesive layer in this order. 1 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention. The polarizing plate 100 with a retardation layer in the illustrated example includes a protective layer 10, a polarizer 20, a retardation layer 30, and an adhesive layer 40 in this order. As shown in FIG. 1, the phase difference layer 30 may be comprised from the 1st liquid crystal alignment solidification layer 31 and the 2nd liquid crystal alignment solidification layer 32. Alternatively, as shown in FIG. 2, the retardation layer 30 may be a single layer of a liquid crystal alignment solidification layer, and another retardation layer 33 may be provided between the retardation layer 30 and the adhesive layer 40. . In the embodiment of the present invention, the retardation layer 30 is typically provided directly on the polarizer 20 (that is, without intervening any layer other than the adhesive layer).

In an embodiment of the present invention, the total thickness of the polarizing plate with a retardation layer from the protective layer to the retardation layer is 80 μm or less, and the storage modulus (G' _-30 ) of the pressure-sensitive adhesive layer at -30°C is 250 kPa or less. By configuring the total thickness from the protective layer to the phase difference layer to be within the above range and specifying the storage modulus of the adhesive layer at -30°C as above, the generation of cracks during bending in a low-temperature environment is suppressed. A polarizer can be realized. In the conventional adhesive provided on a polarizing plate with a retardation layer, the storage elastic modulus in a low-temperature environment (e.g., -30°C) becomes higher compared to the storage elastic modulus in a room temperature environment (e.g., 25°C), and the adhesive may harden. Due to this phenomenon, there is a problem in that the desired bending resistance cannot be obtained in a harsh environment (particularly in a low-temperature environment) in a conventional polarizing plate with a retardation layer. In the present invention, it was found that by using an adhesive whose storage modulus is below a certain value even in a low temperature environment, curing of the adhesive is suppressed and the bending resistance of the polarizing plate with a retardation layer is maintained. In addition, by specifying the ratio of the storage elastic modulus at -30°C and the storage elastic modulus at 25°C of the adhesive within a specific range, the desired storage elastic modulus is satisfied in a wide temperature range including not only a low-temperature environment but also a room temperature environment. Thus, the bending resistance of the polarizing plate with a retardation layer can be maintained.

As described above, the polarizing plate with a retardation layer has a total thickness from the protective layer to the retardation layer of 80 μm or less, preferably 70 μm or less, and more preferably 60 μm or less. The lower limit of the total thickness from the protective layer to the retardation layer may be, for example, 20 μm. When the total thickness from the protective layer to the retardation layer is within this range, a polarizing plate with a retardation layer in which the occurrence of cracks during bending in a low-temperature environment is suppressed can be obtained.

The polarizing plate with a phase contrast layer may further include other optical function layers. The type, characteristics, number, combination, arrangement position, etc. of optical functional layers that can be provided on the polarizing plate with a retardation layer can be appropriately set depending on the purpose. For example, the polarizing plate with a retardation layer may further include a conductive layer or an isotropic base material with a conductive layer (not shown). The conductive layer or the isotropic substrate with a conductive layer is typically provided on the side of the retardation layer 30 opposite to the polarizer 20. When a conductive layer or an isotropic substrate with a conductive layer is provided, the polarizing plate with a retardation layer can be applied to a so-called inner touch panel type input display device in which a touch sensor is incorporated between an organic EL cell and a polarizing plate.

The polarizing plate with a retardation layer may be in a single leaf shape or in a long shape. In this specification, 'elongated shape' means an elongated shape with a sufficiently long length relative to the width, and includes, for example, an elongated shape whose length is 10 or more times the width, preferably 20 times or more. A long polarizing plate with a retardation layer can be wound into a roll.

It is preferable that a release film is temporarily attached to the surface of the adhesive layer 40 until the polarizing plate with a retardation layer is provided for use. By temporarily attaching the release film, the adhesive layer is protected and roll formation of a polarizing plate with a retardation layer becomes possible.

Hereinafter, the components of the polarizing plate with a retardation layer will be described in more detail.

B. Polarizer

Hereinafter, the components of the polarizing plate will be described in more detail.

B-1. polarizer

As the polarizer, any suitable polarizer can be employed. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

Specific examples of polarizers composed of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, and partially saponified ethylene-vinyl acetate copolymer-based films, and iodine and dichroic dyes. Examples include those that have been dyed and stretched with a dichroic substance, and polyene-based oriented films such as dehydrated PVA products and dehydrochloric acid-treated polyvinyl chloride products. Preferably, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching is used because it has excellent optical properties.

The dyeing with iodine is performed, for example, by immersing the 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 dyeing treatment or may be performed while dyeing. Additionally, it may be dyed after stretching. If necessary, the PVA-based film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. For example, by immersing the PVA-based film in water and washing it before dyeing, it is possible to not only clean the surface of the PVA-based film from contamination or anti-blocking agents, but also prevent uneven dyeing by swelling the PVA-based film.

Specific examples of a polarizer obtained using a laminate include 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 applied to the resin substrate. A polarizer obtained using a laminated body of the following can be mentioned. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer formed by applying to the resin substrate is, for example, applied by applying a PVA-based resin solution to a resin substrate, drying it, and forming 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 laminate and using the PVA-based resin layer as a polarizer. In this embodiment, stretching typically includes stretching the laminate by immersing it in an aqueous boric acid solution. Additionally, stretching, if necessary, may further include air stretching the laminate at a high temperature (for example, 95°C or higher) before stretching in an aqueous boric acid solution. The obtained resin substrate/polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled from the resin substrate/polarizer laminate and applied to the peeled surface for the purpose. Any appropriate protective layer may be laminated and used. Details of the manufacturing method of such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 (Japanese Patent Application Publication No. 5414738) and Japanese Patent Application Publication No. 6470455. The entire descriptions of these publications are incorporated herein by reference.

The thickness of the polarizer is preferably 10 μm or less, more preferably 8 μm or less, and still more preferably 6 μm or less. The lower limit of the thickness of the polarizer may be, for example, 1 μm. If the thickness of the polarizer is within this range, curling during heating can be suppressed well, and good external appearance durability during heating can be obtained. Additionally, if the thickness of the polarizer is within this range, the desired total thickness can be achieved.

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

B-2. protective layer

The protective layer is formed from any suitable film. Specific examples of materials that become the main component of the film include cellulose-based resins such as triacetylcellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polyester. Transparent resins such as sulfone-based, polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based, and acetate-based resins can be mentioned. In addition, thermosetting resins or ultraviolet curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, silicone, etc. may also be included. In addition, for example, glassy polymers such as siloxane polymers can also be mentioned. Additionally, the polymer film described in Japanese Patent Application Laid-Open No. 2001-343529 (WO01/37007) can also be used. As a material for 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, for example, isobutene and A resin composition containing an alternating copolymer containing N-methylmaleimide and an acrylonitrile/styrene copolymer can be mentioned. The polymer film may be, for example, an extrusion molded product of the resin composition.

The polarizing plate with a retardation layer according to an embodiment of the present invention is typically disposed on the viewer side of an organic EL display device, and the protective layer 10 is disposed on the viewer side. Accordingly, the protective layer 10 may be subjected to surface treatment such as hard coat treatment, anti-reflection treatment, anti-sticking treatment, or anti-glare treatment as needed.

The thickness of the protective layer is preferably 45 μm or less, more preferably 40 μm or less, and still more preferably 35 μm or less. The lower limit of the thickness of the protective layer may be, for example, 10 μm. In addition, when surface treatment is performed, the thickness of the protective layer 10 is a thickness including the thickness of the surface treatment layer.

C. Phase contrast layer

In one embodiment, the retardation layer 30 has a laminated structure of a first liquid crystal alignment solidification layer 31 and a second liquid crystal alignment solidification layer 32, as described in C-1. In another embodiment, as described in C-2., the retardation layer 30 is a single layer of a liquid crystal alignment solidification layer, and between the retardation layer 30 and the adhesive layer 40, there is another retardation layer. (33) is provided.

C-1. Phase contrast layer having a laminated structure of a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer

C-1-1. First liquid crystal alignment solidification layer

The first liquid crystal alignment solidification layer 31 can function as a so-called λ/2 plate. The first liquid crystal alignment solidification layer is a so-called λ/2 plate, the second liquid crystal alignment solidification layer described later is a so-called λ/4 plate, and their slow axes are set in a predetermined direction with respect to the absorption axis of the polarizer, so that a wide band is achieved. An optical laminate with excellent circular polarization characteristics can be obtained. The in-plane retardation Re(550) of the first liquid crystal alignment-fixed layer is preferably 200 nm to 300 nm, more preferably 220 nm to 290 nm, and still more preferably 250 nm to 280 nm.

The refractive index ellipsoid of the first liquid crystal alignment solidification layer typically shows the relationship of nx>ny=nz. As described above, the angle formed by the slow axis of the first liquid crystal alignment solidification layer 31 and the absorption axis of the polarizer 20 is preferably 10° to 20°, more preferably 13° to 17°, and further. Preferably it is about 15°. If the angle between the slow axis of the first liquid crystal alignment solidification layer and the absorption axis of the polarizer is within this range, the in-plane retardation of the first liquid crystal alignment solidification layer and the second liquid crystal alignment layer is set to a predetermined range, respectively, and the second liquid crystal alignment layer is set to a predetermined range. By arranging the slow axis of the liquid crystal alignment-fixed layer at a predetermined angle as described later with respect to the absorption axis of the polarizer, an optical laminate having very excellent circular polarization properties (as a result, very excellent anti-reflection properties) in a wide band can be obtained. .

The thickness of the first liquid crystal alignment solidification layer is preferably 1 μm to 7 μm, and more preferably 1.5 μm to 2.5 μm. As described above, by using a liquid crystal compound, the difference between nx and ny of the resulting optical compensation layer can be significantly increased compared to a non-liquid crystal material, and therefore the layer thickness for obtaining the desired in-plane retardation can be significantly reduced. Therefore, an in-plane retardation equivalent to that of a resin film can be realized with a thickness significantly thinner than that of a resin film.

The first liquid crystal alignment solidified layer is typically oriented in a state in which rod-shaped liquid crystal compounds are lined up in a predetermined direction (homogeneous orientation). A slow axis may appear in the orientation direction of the liquid crystal compound. Examples of the liquid crystal compound include a liquid crystal compound (nematic liquid crystal) whose liquid crystal phase is a nematic phase. As such a liquid crystal compound, for example, liquid crystal polymer or liquid crystal monomer can be used. The mechanism for expressing liquid crystallinity of the liquid crystal compound may be lyotropic or thermotropic. The liquid crystal polymer and liquid crystal monomer may be used individually or in combination.

When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer or a crosslinkable monomer. This is because the alignment state of the liquid crystal monomer can be fixed by polymerizing or crosslinking (i.e., curing) the liquid crystal monomer. After aligning the liquid crystal monomers, for example, by polymerizing or crosslinking the liquid crystal monomers, the alignment state can be fixed accordingly. Here, polymers are formed by polymerization and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystalline. Therefore, the formed first liquid crystal alignment solidification layer is unlikely to transition into a liquid crystal phase, a glass phase, or a crystal phase due to temperature changes peculiar to liquid crystal compounds, for example. As a result, the first liquid crystal alignment solidification layer becomes a layer that is unaffected by temperature changes and has extremely excellent stability.

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

As the liquid crystal monomer, any suitable liquid crystal monomer may be employed. For example, those described in Japanese Patent Application Publication 2002-533742 (WO00/37585), EP358208 (US5211877), EP66137 (US4388453), WO93/22397, EP0261712, DE19504224, DE4408171, and GB2280445. Polymerizable mesogenic compounds, etc. can be used. Specific examples of such polymerizable mesogenic compounds include, for example, BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Sillicon-CC3767. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable.

The first liquid crystal alignment solidification layer performs an orientation treatment on the surface of a predetermined substrate, applies a coating liquid containing a liquid crystal compound to the surface, orients the liquid crystal compound in a direction corresponding to the orientation treatment, and achieves the orientation. It can be formed by fixing the state. By using such an orientation treatment, the liquid crystal compound can be oriented in a predetermined direction with respect to the elongate direction of the elongated substrate, and as a result, the slow axis can be expressed in the predetermined direction of the formed liquid crystal alignment solidification layer. For example, a liquid crystal alignment solidification layer having a slow axis in a direction of 15° with respect to the long direction can be formed on a long substrate. Even if such a liquid crystal alignment solidification layer is desired to have a slow axis in the diagonal direction, since it can be laminated using roll-to-roll, the productivity of the optical laminate can be significantly improved. In one embodiment, the substrate is any suitable resin film, and the orientation solidification layer formed on the substrate can be transferred to the surface of the polarizer. In another embodiment, the substrate may be an inner protective layer (inner protective film). In this case, the transfer process is omitted, and lamination can be performed by roll-to-roll continuously from the formation of the orientation solidification layer.

As the orientation treatment, any appropriate orientation treatment may be employed. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment can be mentioned. Specific examples of mechanical orientation treatment include rubbing treatment and stretching treatment. Specific examples of physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of chemical alignment treatment include oblique vapor deposition and photo-alignment treatment. The treatment conditions for various orientation treatments may be any appropriate conditions depending on the purpose.

The liquid crystal compound is aligned by treating it at a temperature that exhibits a liquid crystal phase depending on the type of the liquid crystal compound. By performing such temperature treatment, the liquid crystal compound assumes a liquid crystal state, and the liquid crystal compound is aligned according to the orientation treatment direction of the substrate surface.

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

Specific examples of the liquid crystal compound and details of the method for forming the alignment solidification layer are described in Japanese Patent Application Laid-Open No. 2006-163343. The description in this publication is incorporated herein by reference.

C-1-2. Second liquid crystal alignment solidification layer

The second liquid crystal alignment solidification layer 32 can function as a so-called λ/4 plate. The second liquid crystal alignment solidification layer is a so-called λ/4 plate, the first liquid crystal alignment solidification layer is a so-called λ/2 plate as above, and their slow axes are set in a predetermined direction with respect to the absorption axis of the polarizer, An optical laminate having excellent circular polarization properties in a wide band can be obtained. As described above, the in-plane retardation Re(550) of the second liquid crystal alignment-fixed layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and still more preferably 130 nm to 150 nm.

The refractive index ellipsoid of the second liquid crystal alignment solidification layer typically shows the relationship of nx>ny=nz. As described above, the angle formed by the slow axis of the second liquid crystal alignment solidification layer 32 and the absorption axis of the polarizer 20 is preferably 65° to 85°, more preferably 72° to 78°, and further. Preferably it is about 75°. If the angle between the slow axis of the second liquid crystal alignment solidification layer and the absorption axis of the polarizer is within this range, the in-plane retardation of the first liquid crystal alignment solidification layer and the second liquid crystal alignment layer is set to a predetermined range, respectively, and the first liquid crystal alignment solidification layer is set to a predetermined range. By arranging the slow axis of the liquid crystal alignment-fixed layer at the above-described predetermined angle with respect to the absorption axis of the polarizer, an optical laminate having very excellent circular polarization properties (as a result, very excellent anti-reflection properties) in a wide band can be obtained.

The thickness of the second liquid crystal alignment solidification layer is preferably 0.5 μm to 2 μm, and more preferably 1 μm to 1.5 μm.

The constituent materials, characteristics, manufacturing method, etc. of the second liquid crystal alignment solidification layer are the same as those described in Section C-1-1 above with respect to the first liquid crystal alignment solidification layer.

The angle between the slow axis of the first liquid crystal alignment solidification layer 31 and the absorption axis of the polarizer 20 is about 15°, and the slow axis of the second liquid crystal alignment solidification layer 32 and the absorption axis of the polarizer 20 are about 15°. As the embodiment in which the angle formed is about 75° has been described, the relationship between the axis angles may be reversed. Specifically, the angle formed by the slow axis of the first liquid crystal alignment solidification layer 31 and the absorption axis of the polarizer 20 is preferably 65° to 85°, more preferably 72° to 78°, and even more preferably It may be about 75°; In this case, the angle formed by the slow axis of the second liquid crystal alignment solidification layer 32 and the absorption axis of the polarizer 20 is preferably 10° to 20°, more preferably 13° to 17°, even more preferably may be about 15°. In addition, the first liquid crystal alignment solidification layer 31 may be a lambda/4 plate, and the second liquid crystal alignment solidification layer 32 may be a lambda/2 plate.

C-2. A phase contrast layer composed of a single layer of the liquid crystal alignment solidification layer and another phase difference layer.

C-2-1. Single layer of liquid crystal alignment solidification layer

In another embodiment, the retardation layer 30 is a single layer of an alignment-fixed layer of a liquid crystal compound. The phase difference layer can typically function as a λ/4 plate. The refractive index characteristic of the retardation layer typically shows the relationship nx>ny=nz. The in-plane phase difference Re(550) of the retardation layer is preferably 100 nm to 180 nm, more preferably 110 nm to 160 nm, and still more preferably 120 nm to 140 nm. Additionally, here, 'ny=nz' includes not only the case where ny and nz are completely the same, but also the case where they are substantially the same. Therefore, there may be cases where ny > nz or ny < nz within a range that does not impair the effect of the present invention.

The Nz coefficient of the phase difference layer is preferably 0.9 to 1.5, and more preferably 0.9 to 1.3.

The phase difference layer preferably exhibits inverse dispersion wavelength characteristics in which the phase difference value increases depending on the wavelength of the measurement light. In this case, the phase difference layer satisfies the relationship Re(450)<Re(550)<Re(650), and Re(450)/Re(550) of the phase difference layer is preferably 0.8 or more and less than 1, and more Preferably it is 0.8 or more and 0.95 or less. With this configuration, very excellent anti-reflection properties can be achieved.

The angle formed by the slow axis of the retardation layer and the absorption axis of the polarizer is preferably 35° to 55°, more preferably 40° to 50°, even more preferably 42° to 48°, and especially preferably is about 45°. If the angle is in this range, an organic EL display device with very excellent anti-reflection characteristics can be obtained by using the phase difference layer as a λ/4 plate 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.

Representative examples of the resin constituting the resin film include polycarbonate-based resin or polyestercarbonate-based resin (hereinafter sometimes simply referred to as polycarbonate-based resin). As the polycarbonate-based resin, any suitable polycarbonate-based resin can be used as long as the desired moisture permeability is obtained. For example, the polycarbonate resin contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and an alicyclic diol, alicyclic dimethanol, di, tri, or It contains a structural unit derived from at least one dihydroxy compound selected from the group consisting of polyethylene glycol, alkylene glycol, or spiroglycol. Preferably, 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, and a structural unit derived from alicyclic dimethanol and/ or contains structural units derived from di, tri or polyethylene glycol; More preferably, it contains 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. The polycarbonate-based resin may, if necessary, contain structural units derived from other dihydroxy compounds. The retardation layer can be formed by stretching a film made of the polycarbonate-based resin described above under any appropriate stretching conditions. In addition, details of the polycarbonate-based resin and the method of forming the retardation layer are, for example, Japanese Patent Application Laid-Open No. 2014-10291, Japanese Patent Application Laid-Open No. 2014-26266 (Japanese Patent Application Publication No. 5528606), and Japanese Patent Application Publication No. 2015- No. 212816 (Japanese Patent Publication No. 6189355), Japanese Patent Application Laid-Open No. 2015-212817 (Japanese Patent Publication No. 6823899), Japanese Patent Application Publication No. 2015-212818, Japanese Patent Application Publication No. 2017-54093 (Japanese Patent Publication No. 6360821), and Japanese Patent Publication No. 2018-60014 (Japanese Patent Publication No. 6321107). The descriptions of these publications are incorporated herein by reference.

The thickness of the retardation layer can typically be set to a thickness that can properly function as a λ/4 plate.

C-2-2. different phase contrast layers

The polarizing plate with a retardation layer in another embodiment of the present invention may further include another retardation layer 33 between the retardation layer 30 and the adhesive layer 40. The other retardation layer may be a so-called positive C plate, preferably exhibiting a refractive index characteristic of nz>nx=ny. By using a positive C plate as another phase contrast layer, reflection in the oblique direction can be prevented well, and wide viewing angle of the anti-reflection function becomes possible. In this case, the phase difference Rth (550) in the thickness direction of the other retardation layer is preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, further preferably -90 nm to -200 nm, especially preferably -100nm~-180nm. Here, 'nx=ny' includes not only the case where nx and ny are strictly the same, but also the case where nx and ny are substantially the same. That is, the in-plane phase difference Re(550) of the other phase difference layer may be less than 10 nm.

Another retardation layer having a refractive index characteristic of nz>nx=ny may be formed of any suitable material. The other retardation layer preferably consists of a film comprising a liquid crystal material fixed in homeotropic orientation. The liquid crystal material (liquid crystal compound) capable of homeotropic alignment may be a liquid crystal monomer or a liquid crystal polymer. As a specific example of the method of forming the liquid crystal compound and the liquid crystal alignment solidified layer, the liquid crystal compound and the liquid crystal alignment solidified layer described in [0020] to [0028] of Japanese Patent Application Laid-Open No. 2002-333642 (Japanese Patent Publication No. 4174192) Formation methods include: In this case, the thickness of the other retardation layer is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, and still more preferably 0.5 μm to 5 μm.

D. Adhesive layer

In the polarizing plate with a retardation layer according to an embodiment of the present invention, the storage modulus (G' _-30 ) of the pressure-sensitive adhesive layer at -30°C is 250 kPa or less, preferably 200 kPa or less. The lower limit of the storage modulus (G' _-30 ) of the adhesive layer may be, for example, 100 kPa. Additionally, the storage modulus (G' ₂₅ ) of the adhesive layer at 25°C is 100 kPa or less, and is preferably 50 kPa or less. The lower limit of the storage modulus (G' ₂₅ ) of the adhesive layer may be, for example, 10 kPa. Also, preferably, G' _-30 and G' ₂₅ satisfy the following formula (1).

1≤G' _-30 /G' ₂₅ ≤10… (One)

The G'- ₃₀ and G' ₂₅ more preferably satisfy 2≤G' _-30 /G' ₂₅ ≤9, and even more preferably satisfy 3≤G'- ₃₀ /G' ₂₅ ≤8. . In the polarizing plate with a retardation layer according to an embodiment of the present invention, the pressure-sensitive adhesive layer has such a storage modulus that the generation of cracks during bending in a low-temperature environment is suppressed.

The thickness of the adhesive layer is preferably 10 μm to 100 μm, and more preferably 20 μm to 60 μm.

The adhesive forming the adhesive layer contains at least a base polymer. The base polymer is an adhesive component that develops adhesiveness in the adhesive layer 40. Base polymers include, for example, acrylic polymer, silicone polymer, polyester polymer, polyurethane polymer, polyamide polymer, polyvinyl ether polymer, vinyl acetate/vinyl chloride copolymer, modified polyolefin polymer, epoxy polymer, fluorine polymer, and rubber polymer. can be mentioned. The base polymer may be used individually, or two or more types may be used together. From the viewpoint of ensuring good transparency and adhesion in the adhesive layer 40, acrylic polymer is preferably used as the base polymer.

Acrylic polymer is a copolymer of a monomer component containing (meth)acrylic acid alkyl ester in a proportion of 50% by mass or more. '(meth)acrylic acid' means acrylic acid and/or methacrylic acid.

As the (meth)acrylic acid alkyl ester, a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms is preferably used, and (meth)acrylic acid alkyl ester having an alkyl group having 10 to 20 carbon atoms is more preferably used. It is used appropriately. The (meth)acrylic acid alkyl ester may contain a linear or branched alkyl group, or may contain a cyclic alkyl group such as an alicyclic alkyl group.

Examples of (meth)acrylic acid alkyl esters containing a linear or branched alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, and s- (meth)acrylate. Butyl, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate. , octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, (meth)acrylate Dodecyl acrylate (i.e. lauryl acrylate), isotridecyl (meth)acrylate, tetradecyl (meth)acrylate, isotetradecyl (meth)acrylate, pentadecyl (meth)acrylate, cetyl (meth)acrylate, (meth)acrylate. Heptadecyl acrylate, octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, and nonadecyl (meth)acrylate.

Examples of (meth)acrylic acid alkyl esters containing an alicyclic alkyl group include (meth)acrylic acid cycloalkyl esters, (meth)acrylic acid esters containing a bicyclic aliphatic hydrocarbon ring, and (meth)acrylic acid esters containing a tricyclic or more aliphatic hydrocarbon ring. Meth)acrylic acid ester can be mentioned. Examples of (meth)acrylic acid cycloalkyl esters include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate. Examples of (meth)acrylic acid esters containing a bicyclic aliphatic hydrocarbon ring include isobornyl (meth)acrylate. Examples of (meth)acrylic acid esters containing three or more aliphatic hydrocarbon rings include dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclofentanyl (meth)acrylate, and 1-acrylate. Damantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate can be mentioned.

As the (meth)acrylic acid alkyl ester, acrylic acid alkyl ester containing an alkyl group having 3 to 15 carbon atoms is preferably used, and more preferably, n-butyl acrylate, 2-ethylhexyl acrylate, and dodecyl acrylate (i.e. At least one selected from the group consisting of lauryl acrylate) is used.

The proportion of (meth)acrylic acid alkyl ester in the monomer component is preferably 60% by mass or more, more preferably 70% by mass or more, from the viewpoint of appropriately expressing basic properties such as adhesiveness in the adhesive layer. It is more than 80% by mass. The ratio is, for example, 99% by mass or less.

The amount of (meth)acrylic acid C _10-20 chain alkyl ester relative to a total of 100 parts by weight of the monomer components of the acrylic base polymer is preferably 1 part by weight to 40 parts by weight, and more preferably 5 parts by weight to 35 parts by weight. In particular, it is preferable that the amount of lauryl acrylate is within the above range.

The monomer component may include a copolymerizable monomer that can be copolymerized with a (meth)acrylic acid alkyl ester. Examples of copolymerizable monomers include monomers having a polar group. Examples of polar group-containing monomers include monomers containing a nitrogen atom-containing ring, hydroxy group-containing monomers, and carboxyl group-containing monomers. The polar group-containing monomer is helpful in modifying the acrylic polymer, such as introducing crosslinking points into the acrylic polymer and ensuring cohesion of the acrylic polymer.

Monomers containing a nitrogen atom-containing ring include, for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, and N-vinylpipe. Razine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine , N-(meth)acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazine-2- ion, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, and N-vinylisothiazole. As the monomer containing a nitrogen atom-containing ring, N-vinyl-2-pyrrolidone is preferably used.

The proportion of the monomer containing a nitrogen atom-containing ring in the monomer component is preferably 0.1% by mass or more from the viewpoint of ensuring cohesion in the adhesive layer and ensuring adhesion to the adherend in the adhesive layer. Preferably it is 0.3 mass% or more, more preferably 0.55 mass% or more. The ratio is preferably 10% by mass or less from the viewpoint of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer (related to compatibility between various additive components in the adhesive layer and the acrylic polymer). More preferably, it is 5% by mass or less.

Examples of hydroxy group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and (meth)acrylic acid. 4-hydroxybutyl acrylic acid, 6-hydroxyhexyl (meth)acrylic acid, 8-hydroxyoctyl (meth)acrylic acid, 10-hydroxydecyl (meth)acrylic acid, 12-hydroxylauryl (meth)acrylic acid, and ( and 4-hydroxymethylcyclohexyl)methyl (meth)acrylate. As the hydroxy group-containing monomer, 4-hydroxybutyl (meth)acrylate is preferably used, and 4-hydroxybutyl acrylate is more preferably used.

The proportion of the hydroxy group-containing monomer in the monomer component is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, from the viewpoint of introducing a crosslinked structure to the acrylic polymer and ensuring cohesion in the adhesive layer. Preferably it is 0.8 mass% or more. The ratio is preferably 10% by mass or less, more preferably 8% by mass or less, from the viewpoint of adjusting the polarity of the acrylic polymer (related to compatibility between various additive components in the adhesive layer 40 and the acrylic polymer). am.

Examples of carboxylic acid-containing monomers include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

The ratio of the carboxyl group-containing monomer in the monomer component is from the viewpoint of introducing a crosslinked structure to the acrylic polymer, ensuring cohesion in the adhesive layer 40, and ensuring adhesion of the adhesive layer 40 to the adherend, Preferably it is 0.1 mass% or more, more preferably 0.5 mass% or more, and even more preferably 0.8 mass% or more. The ratio is preferably 30% by mass or less, more preferably 25% by mass or less, from the viewpoint of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of corrosion of the adherend due to acid.

The amount of the polar group-containing monomer relative to a total of 100 parts by weight of the monomer components of the acrylic base polymer is preferably 5 parts by weight or more, and may be 6 parts by weight or more, 7 parts by weight or more, or 8 parts by weight or more. On the other hand, as the content of polar monomer increases, the dipole moment of the base polymer increases and the relative dielectric constant increases. Additionally, if the content of polar monomer is excessively large, the glass transition temperature of the polymer increases and adhesive strength at low temperatures tends to decrease. Therefore, the amount of the polar group-containing monomer relative to a total of 100 parts by weight of the monomer components of the acrylic base polymer is preferably 30 parts by weight or less, and may be 25 parts by weight or less.

The monomer component may contain other copolymerizable monomers. Other copolymerizable monomers include, for example, acid anhydride monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, alkoxy group-containing monomers, and aromatic vinyl compounds. These other copolymerizable monomers may be used individually, or two or more types may be used together.

The base polymer has a crosslinked structure in this embodiment. As a method of introducing a crosslinking structure to the base polymer, a base polymer containing a functional group capable of reacting with the crosslinking agent and a crosslinking agent are blended into an adhesive composition, and the base polymer and the crosslinking agent are reacted in the adhesive layer 40, and the base polymer is A method of including a polyfunctional monomer in the monomer component to be formed and polymerizing the monomer component to form a base polymer in which a branched structure (crosslinked structure) is introduced into the polymer chain is included. These methods may be used together.

Acrylic polymer can be formed by polymerizing monomer components. Examples of polymerization methods include solution polymerization, active energy ray polymerization (eg UV polymerization), bulk polymerization, and emulsion polymerization. From the viewpoints of transparency, water resistance, and cost of the adhesive layer 40, solution polymerization and UV polymerization are preferred. As solvents for solution polymerization, for example, ethyl acetate and toluene are used. Additionally, as the polymerization initiator, for example, a thermal polymerization initiator and a photopolymerization initiator are used. The amount of the polymerization initiator used is, for example, 0.05 parts by weight or more, and, for example, 1 part by weight or less, based on 100 parts by weight of the monomer component.

The weight average molecular weight of the acrylic polymer is preferably 100,000 or more, more preferably 300,000 or more, and even more preferably 500,000 or more from the viewpoint of ensuring cohesion in the adhesive layer 40. The weight average molecular weight is preferably 5 million or less, more preferably 3 million or less, and even more preferably 2 million or less. The weight average molecular weight of the acrylic polymer is measured by gel permeation chromatography (GPC) and calculated by conversion to polystyrene.

The glass transition temperature (Tg) of the base polymer is preferably 0°C or lower, more preferably -10°C or lower, and even more preferably -20°C or lower. The glass transition temperature is, for example, -80°C or higher.

The adhesive composition may contain one or two or more types of oligomers in addition to the base polymer. When an acrylic polymer is used as the base polymer, an acrylic oligomer is preferably used as the oligomer. Acrylic oligomer is a copolymer of a monomer component containing (meth)acrylic acid alkyl ester in a proportion of 50% by mass or more, and has a weight average molecular weight of, for example, 1,000 or more and 30,000 or less.

Examples of the crosslinking agent include compounds that react with functional groups (such as hydroxy groups and carboxy groups) contained in the base polymer. Examples of such crosslinking agents include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, carbodiimide crosslinking agents, and metal chelate crosslinking agents. The crosslinking agent may be used individually, or two or more types may be used together. As the crosslinking agent, an isocyanate crosslinking agent, a peroxide crosslinking agent, and an epoxy crosslinking agent are preferably used because they have high reactivity with the hydroxy groups and carboxy groups in the base polymer and facilitate the introduction of a crosslinking structure.

The adhesive composition may contain a silane coupling agent. The content of the silane coupling agent in the adhesive composition is preferably 0.1 part by weight or more, more preferably 0.2 part by weight or more, based on 100 parts by weight of the base polymer. The copper content is preferably 5 parts by weight or less, more preferably 3 parts by weight or less.

The adhesive composition may contain other components as needed. Other ingredients include, for example, tackifiers, plasticizers, softeners, anti-aging agents, fillers, colorants, ultraviolet absorbers, antioxidants, surfactants, and antistatic agents.

[Example]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The measurement method for each characteristic is as follows. Additionally, unless otherwise specified, 'part' 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’). Thickness exceeding 10㎛ was measured using a digital micrometer (manufactured by Anritsu, product name 'KC-351C').

(2) Flexibility

A sample of 100 mm x 30 mm was cut out from the polarizing plate with a retardation layer obtained in the examples and comparative examples to serve as a measurement sample, and measured using a bending tester (manufactured by Yuasa System Equipment Co., Ltd., product name 'CL09 Type D01'). . The measurement temperature was -30°C or 25°C. The bending diameter was ϕ = 3 mm, the number of bending was 500,000 times, and the bending direction was internal bending, measurements were made, and evaluation was made based on the following criteria.

Good: No cracks occurring after 500,000 bending tests

Bad: Cracks occurring after 500,000 bending tests

[Preparation Example 1] Production of adhesive layer A

1. Preparation of acrylic base polymer

In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas introduction pipe, 70 parts by weight of 2-ethylhexyl acrylate (2EHA), 20 parts by weight of n-butyl acrylate (BA), and lauryl acrylate (LA) ) 8 parts by weight, 1 part by weight of 4-hydroxybutyl acrylate (4HBA), 0.6 parts by weight of N-vinyl-2-pyrrolidone (NVP), and 2,2'-azobisisobuty as a thermal polymerization initiator. A mixture containing 0.1 part by weight of ronitrile (AIBN) and ethyl acetate as a solvent (solid content concentration: 47% by mass) was stirred at 56°C for 6 hours in a nitrogen atmosphere (polymerization reaction). As a result, a polymer solution containing an acrylic base polymer was obtained. The weight average molecular weight of the acrylic base polymer in this polymer solution was about 2 million.

2. Preparation of adhesive composition

In the polymer solution, per 100 parts by weight of solid content of the polymer solution, 1.5 parts by weight of the first acrylic oligomer, 0.26 parts by weight of the first crosslinking agent (product name 'Niper BMT-40SV', dibenzoyl peroxide, manufactured by Japan Yuji Co., Ltd.), and 0.26 parts by weight of the second acrylic oligomer. Add 0.02 parts by weight of crosslinking agent (brand name 'Colonate L', trimethylolpropane/tolylene diisocyanate trimer adduct, manufactured by Tosoh) and 0.3 parts by weight of silane coupling agent (brand name 'KBM403', manufactured by Shin-Etsu Chemical Co., Ltd.). and mixed to prepare an adhesive composition.

3. Formation of adhesive layer A

The pressure-sensitive adhesive composition A was applied onto the peeling surface of the first peeling film, one of which had undergone silicone peeling treatment, to form a coating film. The first release film is a polyethylene terephthalate (PET) film (brand name 'Diafoil MRF#75', thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) on which one side has been subjected to a silicone release treatment. Next, the peeling-treated side of the second peeling film, one of which had undergone a silicone peeling treatment, was bonded to the coating film on the first peeling film. The second release film is a PET film (brand name 'Diafoil MRF#75', thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) on one side of which was subjected to a silicone release treatment. Next, the coating film on the first release film was dried by heating at 100°C for 1 minute and then at 150°C for 3 minutes to form a transparent adhesive layer A with a thickness of 50 μm. The thickness of the obtained adhesive layer A was 50 μm.

[Preparation Example 2] Production of adhesive layer B

1. Preparation of acrylic base polymer

56 parts by weight of 2-ethylhexyl acrylate (2EHA), 34 parts by weight of lauryl acrylate (LA), 7 parts by weight of 4-hydroxybutyl acrylate (4HBA), and N-vinyl-2-pyrrolidone (NVP) ) A mixture containing 2 parts by weight and 0.015 parts by weight of a photopolymerization initiator (brand name 'Omnirad 184' manufactured by IGM Resins) was irradiated with ultraviolet rays (polymerization reaction) to produce a prepolymer composition (polymerization rate of about 10). %) was obtained (the prepolymer composition contains a monomer component that has not undergone a polymerization reaction).

2. Preparation of adhesive composition

Next, 100 parts by weight of the prepolymer composition, 0.08 parts by weight of 1,6-hexanediol diacrylate (HDDA), 1 part by weight of the second acrylic oligomer, and a silane coupling agent (product name 'KBM403', Shin-Etsu Chemical Co., Ltd. 0.3 parts by weight (manufactured by Kyoto) was mixed to prepare a photocurable adhesive composition.

3. Formation of adhesive layer B

Pressure-sensitive adhesive composition B was applied on the peeling surface of the first peeling film, one of which had undergone silicone peeling treatment, to form a coating film. The first release film is a polyethylene terephthalate (PET) film (brand name 'Diafoil MRF#75', thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) on which one side has been subjected to a silicone release treatment. Next, the peeling-treated side of the second peeling film, one of which had undergone a silicone peeling treatment, was bonded to the coating film on the first peeling film. The second release film is a PET film (brand name 'Diafoil MRF#75', thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) on one side of which was subjected to a silicone release treatment. Next, the coating film was irradiated with ultraviolet rays through the second peeling film to cure the coating film with ultraviolet rays. A black light was used for ultraviolet irradiation. The irradiation intensity of ultraviolet light was set to 5 mW/cm ² . The thickness of the obtained adhesive layer B was 50 μm.

[Preparation Example 3] Production of adhesive layer C

1. Preparation of acrylic base polymer

44 parts by weight of 2-ethylhexyl acrylate (2EHA), 43 parts by weight of lauryl acrylate (LA), 6 parts by weight of 4-hydroxybutyl acrylate (4HBA), and N-vinyl-2-pyrrolidone (NVP) ) A mixture containing 7 parts by weight and 0.015 parts by weight of a photopolymerization initiator (brand name 'Omnirad 184' manufactured by IGM Resins) was irradiated with ultraviolet rays (polymerization reaction) to obtain a prepolymer composition (polymerization rate of about 10%). The prepolymer composition contains monomer components that have not undergone a polymerization reaction).

2. Preparation of adhesive composition

Next, 100 parts by weight of the prepolymer composition, 0.08 parts by weight of 1,6-hexanediol diacrylate (HDDA), 1 part by weight of the second acrylic oligomer, and a silane coupling agent (product name 'KBM403', Shin-Etsu Chemical Co., Ltd. (manufactured by Kyoto) was mixed with 0.3 parts by weight to prepare a photocurable adhesive composition.

3. Formation of adhesive layer C

The pressure-sensitive adhesive composition C was applied onto the peeling surface of the first peeling film, one of which had undergone silicone peeling treatment, to form a coating film. The first release film is a polyethylene terephthalate (PET) film (brand name 'Diafoil MRF#75', thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) on which one side has been subjected to a silicone release treatment. Next, the peeling-treated side of the second peeling film, one of which had undergone a silicone peeling treatment, was bonded to the coating film on the first peeling film. The second release film is a PET film (brand name 'Diafoil MRF#75', thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) on one side of which was subjected to a silicone release treatment. Next, the coating film was irradiated with ultraviolet rays through the second peeling film to cure the coating film with ultraviolet rays. A black light was used for ultraviolet irradiation. The irradiation intensity of ultraviolet light was set to 5 mW/cm ² . The thickness of the obtained adhesive layer C was 25 μm.

[Preparation Example 4] Production of adhesive layer D

1. Preparation of acrylic polymer

In a four-neck flask equipped with a stirring blade, thermometer, nitrogen gas introduction tube, and condenser, 94.9 parts by weight of butylacrylate (BA), 0.1 parts by weight of 2-hydroxyethyl acrylate (HEA), and 5 parts by weight of acrylic acid (AA) were added. A monomer mixture containing In addition, with respect to 100 parts by weight of the monomer mixture (solid content), 0.2 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator was introduced together with ethyl acetate, and nitrogen gas was introduced while gently stirring to replace nitrogen. Afterwards, the liquid temperature in the flask was maintained at around 55°C and a polymerization reaction was performed for 7 hours. After that, ethyl acetate was added to the obtained reaction liquid to prepare an acrylic polymer solution with a weight average molecular weight of 2.2 million, with the solid content concentration adjusted to 30%.

2. Preparation of adhesive composition

Based on 100 parts by weight of solid content of the obtained acrylic polymer solution, 0.6 parts by weight of trimethylolpropane/tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Kogyo, brand name 'Colonate L') as a crosslinking agent, and a silane coupling agent (product name: An adhesive composition was obtained by adding 0.2 parts by weight of KBM403 (manufactured by Shin-Etsu Chemical Co., Ltd.) and stirring.

3. Formation of adhesive layer D

The acrylic adhesive composition was uniformly applied using a fountain coater to the surface of a release film containing a polyethylene terephthalate film (PET film, transparent substrate) with a thickness of 38 ㎛ treated with a silicone-based release agent, and placed at an air circulation constant temperature of 155°C. It was dried in an oven for 2 minutes to form an adhesive layer D with a thickness of 50 μm.

[Preparation Example 5] Production of adhesive layer E

1. Preparation of acrylic polymer

A monomer mixture containing 99 parts by weight of butylacrylate (BA) and 1 part by weight of 4-hydroxybutylacrylate (HBA) was introduced into a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas introduction tube, and condenser. Additionally, with respect to 100 parts by weight of the monomer mixture, 0.1 part by weight of 2,2'-azobisisobutyronitrile (AIBN) was introduced together with ethyl acetate as a polymerization initiator, and nitrogen gas was introduced while gently stirring to replace nitrogen. The liquid temperature in the flask was maintained at around 55°C and polymerization reaction was performed for 7 hours. Thereafter, ethyl acetate was added to the obtained reaction liquid to prepare an acrylic polymer solution with a weight average molecular weight of 1.8 million, with the solid content concentration adjusted to 30%.

2. Preparation of adhesive composition

Based on 100 parts of solid content of the obtained acrylic polymer solution, 0.1 part of trimethylolpropane/xylylene diisocyanate adduct (manufactured by Tosoh Corporation, brand name 'Takenate D110N') and 0.3 part of peroxide crosslinking agent (manufactured by Nippon Yuji Corporation, brand name 'Niper BMT') ') were mixed in this order to obtain an adhesive composition.

3. Formation of adhesive layer E

The acrylic adhesive composition was uniformly applied using a fountain coater to the surface of a release film containing a polyethylene terephthalate film (PET film, transparent substrate) with a thickness of 38 ㎛ treated with a silicone-based release agent, and placed at an air circulation constant temperature of 155°C. It was dried in an oven for 2 minutes to form an adhesive layer E with a thickness of 50 μm.

[Example 1]

1. Fabrication of polarizer

As a thermoplastic resin substrate, an amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) with 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.

Potassium iodide is added to 100 parts by weight of PVA-based resin, which is a 9:1 mixture of polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Japan Synthetic Chemical Industry Co., Ltd., product name 'Gosephimer Z410'). 13 parts by weight was dissolved in water to prepare a PVA aqueous solution (coating solution).

The PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60°C to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate.

The obtained laminate was free-end uniaxially stretched 2.4 times in the machine direction (longitudinal direction) between rolls with different circumferential speeds in an oven at 130°C (air auxiliary stretching treatment).

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

Next, in a dyeing bath (iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30°C, the final polarizer has a single transmittance (Ts) of 43.0% or more. It was immersed for 60 seconds while adjusting the concentration to achieve this (dyeing treatment).

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

Thereafter, the laminate was immersed in an aqueous solution of boric acid (boric acid concentration: 4.0% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70°C, while the total stretch ratio was stretched in the longitudinal direction (longitudinal direction) between rolls with different circumferential speeds. Uniaxial stretching was performed to increase the size by 5.5 times (underwater stretching treatment).

Thereafter, the laminate was immersed in a washing bath (aqueous solution obtained by mixing 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).

Afterwards, it was dried in an oven maintained at 90°C and brought into contact with a SUS heating roll whose surface temperature was maintained at 75°C for about 2 seconds (dry shrink treatment). The shrinkage rate in the width direction of the laminate by dry shrinkage treatment was 5.2%.

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

2. Production of polarizer

An acrylic resin film (thickness 20 μm) was bonded to the surface of the polarizer obtained above through a PVA-based adhesive. In this way, a polarizing plate having a structure of acrylic resin film/adhesive/polarizer was obtained.

3. Fabrication of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer

10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF, brand name 'Paliocolor LC242', shown in the formula below) and 3 g of a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF, brand name 'Irgacure 907') , was dissolved in 40 g of toluene to prepare a liquid crystal composition (coating solution).

The surface of a polyethylene terephthalate (PET) film (thickness 38 μm) was rubbed using a rubbing cloth to perform orientation treatment. The direction of the orientation treatment was set to be 15° when viewed from the viewer's side with respect to the direction of the absorption axis of the polarizer when bonding to the polarizing plate. The liquid crystal coating liquid was applied to this alignment treated surface using a bar coater, and the liquid crystal compound was aligned by heating and drying at 90°C for 2 minutes. The liquid crystal layer formed in this way was irradiated with light at 1 mJ/cm ² using a metal halide lamp to cure the liquid crystal layer, thereby forming a first liquid crystal alignment solidification layer on the PET film. The thickness of the first liquid crystal alignment solidification layer was 2.5 μm, and the in-plane retardation Re(550) was 270 nm. Additionally, the first liquid crystal alignment solidification layer had a refractive index distribution of nx>ny=nz.

A second liquid crystal alignment solidification layer was formed on the PET film in the same manner as above except that the coating thickness was changed and the orientation treatment direction was 75° when viewed from the viewer's side with respect to the direction of the absorption axis of the polarizer. The thickness of the second liquid crystal alignment solidification layer was 1.5 μm, and the in-plane retardation Re(550) was 140 nm. Additionally, the second liquid crystal alignment solidification layer had a refractive index distribution of nx>ny=nz. Additionally, Re(450)/Re(550) of the first liquid crystal alignment solidification layer and B was 1.11.

4. Production of polarizer with phase contrast layer

The first liquid crystal alignment solidified layer and the second liquid crystal alignment solidification layer obtained in the above 3. were transferred to the polarizer surface of the polarizing plate obtained in the above 2. in this order. At this time, transfer (lamination) is performed so that the angle between the absorption axis of the polarizer and the slow axis of the first liquid crystal alignment solidification layer is 15°, and the angle between the absorption axis of the polarizer and the slow axis of the second liquid crystal alignment solidification layer is 75°. was carried out. In addition, each transfer (lamination) was performed through an ultraviolet curing adhesive (thickness 1.0 μm). Next, the adhesive layer A (thickness 50 micrometers) obtained in Production Example 1 was arrange|positioned on the surface of the 2nd liquid crystal alignment solidification layer. In this way, a polarizing plate with a retardation layer having the structure of acrylic resin film/adhesive/polarizer/1st liquid crystal alignment solidification layer/2nd liquid crystal alignment solidification layer/adhesive layer A was obtained. The obtained polarizing plate with a retardation layer was used for the evaluation of (2) above. The results are shown in Table 1.

[Example 2]

A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that the thickness of the adhesive layer was 25 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as Example 1. The results are shown in Table 1.

[Example 3]

A polarizing plate was produced according to procedure 1. below, and instead of the first liquid crystal alignment layer and the second liquid crystal alignment layer in Example 1, a single layer of the liquid crystal alignment layer was prepared according to 2. and 3. below. A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that another retardation layer was produced. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as Example 1. The results are shown in Table 1.

1. Production of polarizer

The HC-TAC film was bonded to the surface of the polarizer obtained in step 1 of Example 1 through an ultraviolet curing adhesive. Specifically, the curable adhesive was applied to a thickness of 1.0 μm and bonded using a roll machine. Afterwards, UV rays were irradiated from the HC-TAC film side to cure the adhesive. Additionally, the HC-TAC film is a film in which a hard coat (HC) layer (7 μm thick) is formed on a triacetylcellulose (TAC) film (25 μm thick). In this way, a polarizing plate having a structure of HC-TAC film/polarizer was obtained.

2. Fabrication of a single layer of liquid crystal alignment solidification layer

55 parts of the compound represented by formula (I), 25 parts of the compound represented by formula (II), and 20 parts of the compound represented by formula (III) were added to 400 parts of cyclopentanone (CPN), then heated to 60°C and stirred to dissolve. After dissolution was confirmed, the temperature was returned to room temperature, 3 parts of Irgacure 907 (manufactured by BASF Japan Co., Ltd.), 0.2 parts of Megapak F-554 (manufactured by DIC Corporation), and p-methoxyphenol. 0.1 part of (MEHQ) was added and further stirred to obtain a solution. The solution was clear and homogeneous. The obtained solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. Meanwhile, the polyimide solution for an alignment film was applied to a glass substrate with a thickness of 0.7 mm using a spin coat method, dried at 100°C for 10 minutes, and then baked at 200°C for 60 minutes to obtain a coating film. The obtained coating film was subjected to a rubbing treatment to form an alignment film. The rubbing treatment was performed using a commercially available rubbing device. The polymerizable composition obtained above was applied to a substrate (substantially an alignment film) by spin coating and dried at 100°C for 2 minutes. After cooling the obtained coating film to room temperature, it was irradiated with ultraviolet rays at an intensity of 30 mW/cm ² for 30 seconds using a high-pressure mercury lamp to obtain a first liquid crystal alignment solidification layer. The in-plane retardation Re(550) of the first liquid crystal alignment solidification layer was 130 nm. In addition, Re(450)/Re(550) of the liquid crystal alignment solidification layer was 0.851, showing inverse dispersion wavelength characteristics.

3. Fabrication of different phase contrast layers

20 parts by weight of a side-chain liquid crystal polymer represented by the following formula (I) (the numbers 65 and 35 in the formula represent the mole percent of the monomer unit, and are conveniently expressed as a block polymer: weight average molecular weight 5000), showing a nematic liquid crystalline phase. A liquid crystal coating solution was prepared by dissolving 80 parts by weight of polymerizable liquid crystal (manufactured by BASF, brand name: PaliocolorLC242) and 5 parts by weight of a photopolymerization initiator (manufactured by Chiba Specialty Chemicals, brand name: Irgacure 907) in 200 parts by weight of cyclopentanone. Then, the coating liquid was applied to a base film (norbornene-based resin film: manufactured by Nippon Zeon Co., Ltd., brand name "Zeonex") using a bar coater, and then heated and dried at 80°C for 4 minutes to orient the liquid crystal. This liquid crystal layer was irradiated with ultraviolet rays to harden the liquid crystal layer, thereby forming a second liquid crystal alignment solidification layer (thickness: 0.58 μm) on the substrate. This layer's Re(550) was 0nm, Rth(550) was -80nm, and it showed refractive index characteristics of nz>nx=ny.

[Example 4]

A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that the adhesive layer B obtained in Production Example 2 was used. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as Example 1. The results are shown in Table 1.

[Comparative Example 1]

A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that the adhesive layer D obtained in Production Example 4 was used. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as Example 1. The results are shown in Table 1.

[Comparative Example 2]

A polarizing plate with a retardation layer was obtained in the same manner as in Comparative Example 1 except that the thickness of the adhesive layer was 25 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as Example 1. The results are shown in Table 1.

[Comparative Example 3]

A polarizing plate with a retardation layer was obtained in the same manner as in Comparative Example 1 except that the thickness of the adhesive layer was 15 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as Example 1. The results are shown in Table 1.

[Comparative Example 4]

A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that the adhesive layer E obtained in Production Example 5 was used. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as Example 1. The results are shown in Table 1.

[Comparative Example 5]

A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that the adhesive layer C obtained in Production Example 3 was used and the thickness of the adhesive layer was set to 25 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as Example 1. The results are shown in Table 1.

[Comparative Example 6]

Examples except that a polarizer (thickness 12 μm) formed from a PVA-based resin film was used as the polarizer, and an inner protective layer (TAC film, thickness 25 μm) was provided on the opposite side of the HC-TAC film of the polarizer. In the same manner as in 3, a polarizing plate with a retardation layer was obtained. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as Example 1. The results are shown in Table 1.

[Comparative Example 7]

A polarizing plate with a retardation layer was obtained in the same manner as in Comparative Example 6 except that the thickness of the adhesive layer was 25 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as Example 1. The results are shown in Table 1.

[Table 1]

[evaluation]

As is clear from FIG. 1, according to an embodiment of the present invention, it is possible to obtain a polarizing plate with a retardation layer in which the occurrence of cracks during bending in a low-temperature environment is suppressed. On the other hand, in all of the polarizing plates with a retardation layer of the comparative examples, cracks occurred in the bending test. For example, in Comparative Example 1, cracks occurred along the absorption axis direction of the polarizer, and in Comparative Example 6, cracks occurred along the absorption axis direction of the polarizer and the bending direction of the bending test.

The polarizing plate with a retardation layer of the present invention is suitably used in an organic EL display device.

10: Polarizer
10: protective layer
20: Polarizer
30: Phase contrast layer
31: First liquid crystal alignment solidification layer
32: Second liquid crystal alignment solidification layer
33: Other phase contrast layer
40: Adhesive layer
100: Polarizer with phase contrast layer
101: Polarizer with phase contrast layer

Claims (14)

A protective layer, a polarizer, a retardation layer, and an adhesive layer are provided in this order,
The total thickness from the protective layer to the retardation layer is 80㎛ or less,
The storage modulus (G' _-30 ) of the adhesive layer at -30°C is 250 kPa or less,
Polarizer with phase contrast layer. According to paragraph 1,
A polarizer with a retardation layer in which the storage modulus of the adhesive layer at -30°C (G' _-30 ) and the storage modulus of the adhesive layer at 25°C ( _G'25 ) satisfy the following equation (1):
1≤G' _-30 /G' ₂₅ ≤10… (One). According to claim 1 or 2,
A polarizing plate with a retardation layer, wherein the pressure-sensitive adhesive layer has a storage modulus (G' _-30 ) of 200 kPa or less at -30°C. According to any one of claims 1 to 3,
A polarizing plate with a retardation layer, wherein the adhesive layer is made of an acrylic adhesive containing an acrylic base polymer. According to paragraph 4,
A polarizing plate with a retardation layer in which the acrylic base polymer contains 1 part by weight to 40 parts by weight of (meth)acrylic acid C _10-20 chain alkyl ester based on a total of 100 parts by weight of the monomer components. According to clause 5,
A polarizing plate with a retardation layer, wherein the acrylic base polymer is the (meth)acrylic acid C _10-20 chain alkyl ester and contains lauryl acrylate. According to any one of claims 4 to 6,
The acrylic base polymer contains 5 to 30 parts by weight of at least one polar group-containing monomer selected from a monomer containing a nitrogen atom ring, a hydroxy group-containing monomer, and a carboxyl group-containing monomer, based on a total of 100 parts by weight of the monomer component. A polarizer with a phase contrast layer. According to any one of claims 4 to 7,
A polarizing plate with a retardation layer, wherein the acrylic base polymer contains 10 parts by weight or less of a hydroxy group-containing monomer based on a total of 100 parts by weight of the monomer components. According to any one of claims 1 to 8,
A polarizing plate with a retardation layer, wherein the total thickness from the protective layer to the retardation layer is 60 μm or less. According to any one of claims 1 to 9,
A polarizing plate with a retardation layer, wherein the thickness of the polarizer is 10 μm or less. According to any one of claims 1 to 10,
A polarizing plate with a retardation layer, wherein the thickness of the protective layer is 45㎛ or less. According to any one of claims 1 to 11,
The phase difference layer has a laminated structure of a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer, the Re(550) of the first liquid crystal alignment layer is 200 nm to 300 nm, and the slow axis and the absorption of the polarizer are The angle formed by the axis is 10° to 20°, the Re (550) of the second liquid crystal alignment solidification layer is 100 nm to 190 nm, and the angle formed between its slow axis and the absorption axis of the polarizer is 70° to 80°, Polarizer with phase contrast layer. According to any one of claims 1 to 11,
The phase difference layer is a single layer of a liquid crystal alignment solidification layer, the Re (550) of the phase difference layer is 100 nm to 180 nm, and satisfies the relationship of Re (450) < Re (550) < Re (650), A polarizing plate with a retardation layer, wherein the angle between the slow axis and the absorption axis of the polarizer is 35° to 55°. According to clause 13,
A polarizing plate with a retardation layer, further comprising another retardation layer, wherein the other retardation layer exhibits a refractive index characteristic of nz>nx=ny.