KR20240088853A - Polarizer with phase contrast layer - Google Patents

Abstract

The present invention provides a polarizing plate with a retardation layer in which adhesive overflow, adhesive failure, adhesive misalignment, and process contamination are suppressed, and 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, and the total thickness from the protective layer to the retardation layer is 20 ㎛ or more and 60 ㎛ or less, and the adhesive layer The glass transition temperature is -60°C or more and -40°C or less, and the creep value at 25°C is 10% or more and 150% 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 typified 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). Recently, foldable 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 in low-temperature environments and cracks occurring when folded. In addition, there are problems such as glue displacement at the end of the polarizer attached with the retardation layer, which may cause glue overflow, glue shortage, or process contamination.

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 polarizer with a retardation layer in which adhesive overflow, adhesive lack, adhesive misalignment, and process contamination are suppressed, and the occurrence of cracks is suppressed in a low-temperature environment. It's in doing.

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, and the total thickness from the protective layer to the retardation layer is 20 ㎛ or more and 60 ㎛ or less, and the adhesive layer The glass transition temperature is -60°C or more and -40°C or less, and the creep value of the adhesive layer at 25°C is 10% or more and 150% or less.

In one embodiment, the total thickness from the protective layer to the retardation layer is 55 μm or less.

In one embodiment, the glass transition temperature of the pressure-sensitive adhesive layer is -60°C or higher and -45°C or lower.

In one embodiment, the creep value at 25°C is 10% or more and 130% or less.

In one embodiment, the adhesive layer is composed of an acrylic adhesive containing an acrylic base polymer, and the acrylic base polymer is (meth)acrylic acid C _10-20 chain alkyl ester based on a total of 100 parts by weight of the monomer component. It contains 1 to 30 parts by weight.

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

In one embodiment, the acrylic base polymer contains 0.1 to 5 parts by weight of a hydroxy group-containing monomer based on a total of 100 parts by weight of the monomer components.

In one embodiment, the acrylic base polymer contains 0.1 to 1.5 parts by weight of a monomer having a nitrogen atom-containing ring based on a total of 100 parts by weight of the monomer components.

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

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

In one embodiment, the retardation layer has a laminate structure of an alignment-fixed layer of a first liquid crystal compound and an alignment-fixed layer of a second liquid crystal compound, and the Re(550) of the alignment-fixed layer of the first liquid crystal compound is 200 nm to 200 nm. It is 300 nm, the angle between its slow axis and the absorption axis of the polarizer is 10° to 20°, and the Re (550) of the alignment-fixed layer of the second liquid crystal compound is 100 nm to 190 nm, and the angle between its slow axis and the absorption axis of the polarizer is 10° to 20°. The angle formed by the absorption axis is 70° to 80°.

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

In one embodiment, the thickness of the adhesive layer is 20 μm or more.

According to the embodiment of the present invention, it is possible to realize a polarizing plate with a retardation layer in which adhesive overflow, adhesive missing, adhesive misalignment, and process contamination are suppressed, and 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 FIG. 1 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 retardation layer 30 consists of an alignment-fixed layer of the first liquid crystal compound (hereinafter, sometimes referred to as the first liquid-crystal alignment-fixed layer) 31 and an alignment-fixed layer of the second liquid crystal compound (hereinafter, , may be referred to as a second liquid crystal alignment solidification layer) 32, and as shown in FIG. 2, the retardation layer 30 may be comprised of a single layer of the liquid crystal alignment solidification layer. Another retardation layer 33 (example in FIG. 2 only) 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 interposing a layer other than the adhesive layer). In addition, in this specification, the term 'liquid crystal alignment solidification layer' refers to a layer in which a liquid crystal compound is oriented in a predetermined direction within the layer and the orientation state is fixed. In addition, the 'alignment solidification layer' is a concept that includes an alignment hardening layer obtained by curing a liquid crystal monomer, as will be described later.

The polarizing plate with a retardation layer has a total thickness from the protective layer to the retardation layer of 20 ㎛ or more and 60 ㎛ or less, and preferably 25 ㎛ or more and 55 ㎛ or less. If 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.

In an embodiment of the present invention, the glass transition temperature of the pressure-sensitive adhesive layer is -60°C or higher and -40°C or lower, preferably -60°C or higher and -45°C or lower, and more preferably -50°C or higher and -45°C or lower. am. If the glass transition temperature of the pressure-sensitive adhesive layer is within this range, the pressure-sensitive adhesive layer has low elasticity even in a low-temperature environment, and a polarizing plate with a retardation layer with suppressed crack generation during bending in a low-temperature environment can be obtained.

In an embodiment of the present invention, the pressure-sensitive adhesive layer has a creep value at 25°C of 10% to 150%, preferably 10% to 130%, and more preferably 30% to 130%. If the creep value of the adhesive layer at 25°C is within this range, a polarizing plate with a retardation layer in which adhesive overflow, adhesive lack, adhesive misalignment, and process contamination is suppressed can be obtained. Also, creep refers to the amount of deformation of a material when a certain amount of stress is applied over a certain period of time. The creep value can be measured and calculated using, for example, a viscoelasticity measuring device. In the viscoelasticity measuring device, since the pressure-sensitive adhesive is laminated on a parallel plate and the measurement is performed, it is possible to measure the creep value of the pressure-sensitive adhesive itself without depending on the thickness.

Conventional polarizing plates with a retardation layer have problems such as insufficient bending resistance in low-temperature environments and cracks occurring when folded. In response to this problem, a new problem was discovered in that when a low-elastic adhesive is used in a low-temperature environment, adhesive misalignment occurs at the end of the polarizer with a retardation layer, causing adhesive overflow, adhesive lack, and process contamination. As a result of careful study of the problem, the inventors found that the problem could be solved by optimizing the glass transition temperature and creep value of the adhesive layer to a predetermined range. Specifically, the present invention uses an adhesive having a glass transition temperature of -60°C or more and -40°C or less and a creep value of 10% or more and 150% or less at 25°C to prevent adhesive overflow, adhesive lack, adhesive misalignment, and adhesive misalignment. It was discovered that both suppression of process contamination and suppression of cracks during bending in a low-temperature environment were possible.

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, a 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 embedded between an organic EL cell and a polarizing plate.

The polarizing plate with a phase contrast layer may be sheet-shaped or elongated. 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 with a length of 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 liner is temporarily attached to the surface of the pressure-sensitive adhesive layer until the polarizing plate with a retardation layer is provided for use. By temporarily attaching the release liner, 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, each component of the polarizer 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 ethylene-vinyl acetate copolymer-based partially saponified films, with iodine and dichroism (II). Examples include those that have been dyed and stretched with dichroic substances such as dyes, 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 and anti-blocking agents, but also to swell the PVA-based film to prevent staining in the dyeing process.

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 laminate of a resin substrate and a PVA-based resin layer applied to the resin substrate. A polarizer obtained by using a sieve 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 to a resin substrate and dried to form a PVA-based resin layer on the resin substrate. and obtaining a laminate of 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, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin substrate. Stretching typically involves immersing the laminate in an aqueous boric acid solution and stretching it. Additionally, stretching may further include air stretching the laminate at a high temperature (eg, 95°C or higher) before stretching in an aqueous boric acid solution, if necessary. Additionally, in this embodiment, the laminate is preferably subjected to dry shrinkage treatment to shrink the laminate by 2% or more in the width direction by heating while conveying in the longitudinal direction. Typically, the manufacturing method of the present embodiment includes performing an aerial auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and a dry shrink treatment on the laminate in this order. By introducing auxiliary stretching, even in the case of applying PVA on a thermoplastic resin, it becomes possible to increase the crystallinity of PVA and achieve high optical properties. Moreover, by simultaneously increasing the orientation of PVA in advance, problems such as a decrease in orientation or dissolution of PVA when immersed in water in the subsequent dyeing process or stretching process can be prevented, making it possible to achieve high optical properties. It becomes. In addition, when the PVA-based resin layer is immersed in a liquid, the disruption of the polyvinyl alcohol molecule orientation and the decrease in orientation can be suppressed compared to the case where the PVA-based resin layer does not contain a halide. Thereby, the optical properties of the polarizer obtained through a treatment process performed by immersing the laminate in a liquid, such as dyeing treatment and underwater stretching treatment, can be improved. Additionally, optical properties can be improved by shrinking the laminate in the width direction through dry shrinkage treatment. 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 Laid-Open No. 2012-73580 (Japanese Patent No. 5414738) and Japanese Patent No. 6470455. The entire description of these publications is incorporated herein by reference.

The thickness of the polarizer is, for example, 12 μm or less, preferably 10 μm or less, more preferably 8 μm or less, and even 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 well suppressed, 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 from 380 nm to 780 nm. The single transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, 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 are the main components of the film include cellulose resins such as triacetylcellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based. Transparent resins such as phone-based, polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based, and acetate-based resins can be mentioned. Additionally, thermosetting resins or ultraviolet curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, silicone, etc. may also be included. In addition to these, 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 and a resin composition containing an alternating copolymer containing N-methylmaleimide and an acrylonitrile/styrene copolymer. 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 placed on the viewer's side of an organic EL display device, and the protective layer is placed on its viewer's side. Therefore, the protective layer may be subjected to surface treatment such as hard coat (HC) treatment, anti-reflection treatment, anti-sticking treatment, or anti-glare treatment as necessary.

The thickness of the protective layer is preferably 45 μm or less, more preferably 40 μm or less, and even 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 is the 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., retardation layer 30 is a single layer of liquid crystal alignment solidification layer. Additionally, in one embodiment, as described in C-3., another retardation layer 33 is provided between the retardation layer 30 and the adhesive layer 40.

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, and the second liquid crystal alignment solidification layer described later is a so-called λ/4 plate, and these slow axes are set in a predetermined direction with respect to the absorption axis of the polarizer, so that in a wide band An optical laminate having excellent circular polarization properties 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 exhibits the relationship 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.

Typically, the first liquid crystal alignment solidified layer is oriented with rod-shaped liquid crystal compounds arranged in a predetermined direction (homogeneous alignment). A slow axis may be expressed 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 and 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. Here, polymers are formed by polymerization, and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystalline. Accordingly, the formed first liquid crystal alignment solidification layer does not undergo transition from a liquid crystalline compound to a liquid crystal phase, a glass phase, or a crystal phase due to a characteristic temperature change, for example. As a result, the first liquid crystal alignment solidification layer becomes a layer with extremely excellent stability that is not affected by temperature changes.

The temperature range in which 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, Japanese Patent Application Publication No. 2002-533742 (WO00/37585), EP 358208 (US 5211877), EP 66137 (US 4388453), WO93/22397, EP 0261712, DE 19504224, DE 4408171 and GB 228 Polymerizability as described in 0445, etc. 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'. I can hear it. 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 maintains the orientation state. It can be formed by fixing . 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 direction of the long picture can be formed on a long base material. Even when such a liquid crystal alignment solidification layer is desired to have a slow axis in the diagonal direction, it can be laminated using roll-to-roll, so 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.

As the orientation treatment, any appropriate orientation treatment may be employed. Specifically, mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment may 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. As for the treatment conditions for various orientation treatments, any appropriate conditions may be adopted depending on the purpose.

The alignment of the liquid crystal compound is performed by treatment 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 aligned liquid crystal compound as described above. When the liquid crystal compound is a polymerizable monomer or a crosslinkable monomer, the alignment state is fixed by subjecting the aligned liquid crystal compound to polymerization treatment or crosslinking treatment as described above.

Specific examples of the liquid crystal compound and details of the method for forming the liquid crystal 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, and the first liquid crystal alignment solidification layer is a so-called λ/2 plate as described above, and their slow axes are set in a predetermined direction with respect to the absorption axis of the polarizer. , an optical laminate with excellent circular polarization characteristics 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 exhibits the relationship 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 70° to 80°, more preferably 72° to 78°, and further. Preferably it is about 75°. If the angle formed by 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 a predetermined angle as described above 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, properties, manufacturing method, etc. of the second liquid crystal alignment solidification layer are the same as 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 70° to 80°, more preferably 72° to 78°, and still more preferably may be about 75°, and 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 13°. It may be 17°, more preferably 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. 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. In addition, 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 of 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 is more preferable. Typically, 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 It is about 45°. If the angle is within this range, an organic EL display device with extremely excellent anti-reflection characteristics can be obtained by using the λ/4 plate as the phase difference layer as described above.

When the retardation layer 30 is composed of a single layer, its thickness is preferably 0.5 μm to 7 μm, and more preferably 1 μm to 5 μm. By using a liquid crystal compound, an in-plane retardation equivalent to that of a resin film can be achieved with a thickness significantly thinner than that of a resin film.

As mentioned above, the retardation layer 30 is preferably an alignment-fixed layer of a liquid crystal compound. By using a liquid crystal compound, the difference between nx and ny of the resulting retardation layer can be significantly increased compared to a non-liquid crystal material, so the thickness of the retardation layer for obtaining the desired in-plane retardation can be significantly reduced. As a result, further thinning of the polarizing plate with a retardation layer can be realized.

The retardation layer, which is an alignment solidification layer of the liquid crystal compound, may be formed using a composition containing a polymerizable liquid crystal compound. In this specification, 'polymerizable liquid crystal compound included in the composition' refers to a compound that has a polymerizable group and has liquid crystallinity. The polymerizable group refers to a group involved in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in the polymerization reaction by active radicals or acids generated from the photopolymerization initiator.

The expression of liquid crystallinity may be thermotropic or lyotropic. Additionally, the composition of the liquid crystal phase may be nematic liquid crystal or smectic liquid crystal. From the viewpoint of ease of manufacture, thermotropic nematic liquid crystal is preferable.

In one embodiment, the retardation layer, which is a single layer, is formed using a composition containing a liquid crystal compound represented by the following formula (1).

L ¹ -SP ¹ -A ¹ -D ³ -G ¹ -D ¹ -Ar-D ² -G ² -D ⁴ -A ² -SP ² -L ² (1)

L ¹ and L ² each independently represent a monovalent organic group, and at least one of L ¹ and L ² represents a polymerizable group. The monovalent organic group includes any suitable group. The polymerizable group represented by at least one of L ¹ and L ² includes a radical polymerizable group (group capable of radical polymerization). As the radical polymerizable group, any suitable radical polymerizable group can be used. Preferably it is an acryloyl group or a methacryloyl group. The acryloyl group is preferable because the polymerization rate is fast and from the viewpoint of improving productivity. A methacryloyl group can similarly be used as a polymerizable group in highly birefringent liquid crystals.

SP ¹ and SP ² are each independently a single bond, a linear or branched alkylene group, or one or more of -CH ₂ - constituting a linear or branched alkylene group having 1 to 14 carbon atoms is -O It represents a divalent linking group substituted with -. Examples of the linear or branched alkylene group having 1 to 14 carbon atoms include preferably methylene group, ethylene group, propylene group, butylene group, pentylene group, and hexylene group.

A ¹ and A ² each independently represent an alicyclic hydrocarbon group or an aromatic ring substituent. A ¹ and A ² are preferably an aromatic ring substituent having 6 or more carbon atoms or a cycloalkylene ring having 6 or more carbon atoms.

D ¹ , D ² , D ³ and D ⁴ each independently represent a single bond or a divalent linking group. Specifically, D ¹ , D ² , D ³ and D ⁴ are single bonds, -O-CO-, -C(=S)O-, -CR ¹ R ² -, -CR ¹ R ² -CR ³ R ⁴ -, -O-CR ¹ R ² -, -CR ¹ R ² -O-CR ³ R ⁴ -, -CO-O-CR ¹ R ² -, -O-CO-CR ¹ R ² -, -CR ¹ R ² -O-CO-CR ³ R ⁴ -, -CR ¹ R ² -CO-O-CR ³ R ⁴ -, -NR ¹ -CR ² R ³ - or -CO-NR ¹ -. However, at least one of D ¹ , D ² , D ³ and D ⁴ represents -O-CO-. Among these, it is preferable that D ³ is -O-CO-, and it is more preferable that D ³ and D ⁴ are -O-CO-. D ¹ and D ² are preferably a single bond. R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a fluorine atom or an alkyl group having 1 to 4 carbon atoms.

G ¹ and G ² each independently represent a single bond or an alicyclic hydrocarbon group. Specifically, G ¹ and G ² may represent an unsubstituted or substituted divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms. Additionally, one or more of -CH ₂ - constituting the alicyclic hydrocarbon group may be substituted with -O-, -S-, or -NH-. G ¹ and G ² preferably represent a single bond.

Ar represents an aromatic hydrocarbon ring or an aromatic heterocycle. Ar represents, for example, an aromatic ring selected from the group consisting of groups represented by the following formulas (Ar-1) to (Ar-6). In the following formulas (Ar-1) to (Ar-6), *1 represents the bonding position with D ¹ and *2 represents the bonding position with D ² .

In formula (Ar-1), Q ¹ represents N or CH, and Q ² represents -S-, -O-, or -N(R ⁵ )-. R ⁵ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

In formulas (Ar-1) to (Ar-6), Z ¹ , Z ² and Z ³ are each independently a hydrogen atom, a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. group, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a halogen atom, a cyano group, a nitro group, -NR ⁶ R ⁷ or -SR ⁸ . R ⁶ to R ⁸ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and Z ¹ and Z ² may be bonded to each other to form a ring. The ring may be any of alicyclic, heterocyclic, and aromatic rings, and is preferably an aromatic ring. The ring formed may be substituted with a substituent.

In formulas (Ar-2) and (Ar-3), A ³ and A ⁴ each independently represent a group selected from the group consisting of -O-, -N(R ⁹ )-, -S-, and -CO-. and R ⁹ represents a hydrogen atom or a substituent. Examples of the substituent represented by R ⁹ include the same substituents that Y ¹ in the above formula (Ar-1) may have.

In the formula (Ar-2), Examples of non-metallic atoms of groups 14 to 16 represented by X include oxygen atom, sulfur atom, unsubstituted or substituted nitrogen atom, and unsubstituted or substituted carbon atom. Examples of the substituent include the same substituents that Y ¹ in the formula (Ar-1) may have.

In formula (Ar-3), D ⁵ and D ⁶ are each independently a single bond, -O-CO-, -C(=S)O-, -CR ¹ R ² -, -CR ¹ R ² -CR ³ R ⁴ -, -O-CR ¹ R ² -, -CR ¹ R ² -O-CR ³ R ⁴ -, -CO-O-CR ¹ R ² -, -O-CO-CR ¹ R ² -, - CR ¹ R ² -O-CO-CR ³ R ⁴ -, -CR ¹ R ² -CO-O-CR ³ R ⁴ -, -NR ¹ -CR ² R ³ - or -CO-NR ¹ -. R ¹ , R ² , R ³ and R ⁴ are as described above.

In the formula (Ar-3), SP ³ and SP ⁴ each independently constitute a single bond, a linear or branched alkylene group having 1 to 12 carbon atoms, or a linear or branched alkylene group having 1 to 12 carbon atoms. One or more of -CH ₂ - represents a divalent linking group substituted with -O-, -S-, -NH-, -N(Q)-, or -CO-, and Q represents a polymerizable group.

In formula (Ar-3), L ³ and L ⁴ each independently represent a monovalent organic group, and at least one of L ³ and L ⁴ and L ¹ and L ² in the formula (1) represents a polymerizable group.

In formulas (Ar-4) to (Ar-6), Ax represents an organic group of 2 to 30 carbon atoms having at least one aromatic ring selected from the group consisting of an aromatic hydrocarbon ring and an aromatic heterocycle. In formulas (Ar-4) to (Ar-6), Ax preferably has an aromatic heterocycle, and more preferably has a benzothiazole ring. In formulas (Ar-4) to (Ar-6), Ay is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms which may be unsubstituted or substituted, or at least one selected from the group consisting of an aromatic hydrocarbon ring and an aromatic heterocycle. It represents an organic group of 2 to 30 carbon atoms having an aromatic ring. In formulas (Ar-4) to (Ar-6), Ay preferably represents a hydrogen atom.

In formulas (Ar-4) to (Ar-6), Q ³ represents a hydrogen atom or an alkyl group of 1 to 6 carbon atoms which may be unsubstituted or have a substituent. In formulas (Ar-4) to (Ar-6), Q ³ preferably represents a hydrogen atom.

Among such Ar, the group (atomic group) represented by the above formula (Ar-4) or the above formula (Ar-6) is preferably used.

Specific examples of the liquid crystal compound represented by the above formula (1) are disclosed in International Publication No. 2018/123551. The description in this publication is incorporated herein by reference. These compounds may be used alone or in combination of two or more types.

C-3. 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 preferably be a so-called positive C plate, which exhibits a refractive index characteristic of nz>nx=ny. If a positive C plate is used 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 - It is 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.

Other retardation layers having refractive index characteristics of nz>nx=ny may be formed from any suitable material. The other retardation layer preferably comprises 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 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 even 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 invention, the glass transition temperature of the pressure-sensitive adhesive layer is -60°C or higher and -40°C or lower, preferably -60°C or higher and -45°C or lower, and more preferably -50°C or higher. It is above ℃ and below -45℃. If the glass transition temperature of the adhesive layer is within this range, 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.

The thickness of the adhesive layer is preferably 10 μm or more, and more preferably 20 μm or more. The upper limit of the thickness of the adhesive layer may be, for example, 100 μm.

The adhesive forming the adhesive layer typically includes a base polymer. The base polymer is an adhesive component that develops adhesiveness in the adhesive layer. 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. You can. 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, an acrylic polymer is preferably used as the base polymer.

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

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

Examples of (meth)acrylic acid alkyl esters having a linear or branched alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, 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)acrylic acid. Dodecyl (i.e. lauryl acrylate), isotridecyl (meth)acrylate, tetradecyl (meth)acrylate, isotetradecyl (meth)acrylate, pentadecyl (meth)acrylate, cetyl (meth)acrylate, (meth)acrylate Examples include heptadecyl acrylate, octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, and nonadecyl (meth)acrylate.

In embodiments of the present invention, (meth)acrylic acid alkyl esters having a branched alkyl group can be suitably used. As the (meth)acrylic acid alkyl ester having a branched alkyl group, a (meth)acrylic acid alkyl ester having an alkyl group having 6 to 10 carbon atoms is preferably used, and (meth)acrylic acid having an alkyl group having 7 to 9 carbon atoms is more preferably used. Alkyl esters are used. Preferably, 2-ethylhexyl (meth)acrylate can be used.

Examples of (meth)acrylic acid alkyl esters having an alicyclic alkyl group include (meth)acrylic acid cycloalkyl esters, (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring, and (meth)acrylic acid esters having three or more aliphatic hydrocarbon rings. I can hear it. 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 having a bicyclic aliphatic hydrocarbon ring include isobornyl (meth)acrylate. Examples of (meth)acrylic acid esters having three or more aliphatic hydrocarbon rings include dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclofentanyl (meth)acrylate, and 1-adamantyl. (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.

As the alkyl (meth)acrylate, alkyl acrylate having an alkyl group of 3 to 15 carbon atoms is preferably used, and more preferably n-butyl acrylate, 2-ethylhexyl acrylate, and dodecyl acrylate (i.e., lauryl acrylate) are used. ) is used.

The amount of alkyl (meth)acrylate relative to a total of 100 parts by weight of the monomer component of the acrylic base polymer is preferably 50 parts by weight or more, more preferably 60 parts by weight, from the viewpoint of appropriately expressing basic properties such as adhesiveness in the adhesive layer. It is at least 70 parts by weight, more preferably at least 70 parts by weight. The ratio is, for example, 99 parts by weight or less.

The amount of (meth)acrylic acid C _3-5 chain alkyl ester relative to a total of 100 parts by weight of the monomer component of the acrylic base polymer is preferably 10 parts by weight to 30 parts by weight, and more preferably 15 parts by weight to 25 parts by weight. In particular, it is preferable that the amount of n-butyl acrylate is within the above range.

The amount of (meth)acrylic C _6-10 branched alkyl ester relative to a total of 100 parts by weight of the monomer component of the acrylic base polymer is preferably 50 to 90 parts by weight, and more preferably 60 to 80 parts by weight. In particular, it is preferable that the amount of 2-ethylhexyl (meth)acrylate is within the above range.

The amount of (meth)acrylic acid C _10-20 chain alkyl ester relative to a total of 100 parts by weight of the monomer component of the acrylic base polymer is preferably 1 part by weight to 30 parts by weight, more preferably 5 parts by weight to 20 parts by weight, and 6 parts by weight. ~10 parts by weight is more preferable. In particular, it is preferable that the amount of dodecyl acrylate (i.e., 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 having a nitrogen atom-containing ring, hydroxy group-containing monomers, and carboxyl group-containing monomers. Monomers containing polar groups are helpful in modifying acrylic polymers, such as introducing crosslinking points into acrylic polymers and ensuring cohesion of acrylic polymers.

Monomers having a nitrogen atom-containing ring include, for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, 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-oxazin-2-one, N -Vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, and N-vinylisothiazole. As the monomer having a nitrogen atom-containing ring, N-vinyl-2-pyrrolidone is preferably used.

The amount of the monomer having a nitrogen atom-containing ring relative to a total of 100 parts by weight of the monomer component of the acrylic base polymer is preferably It is 0.1 part by weight or more, more preferably 0.3 part by weight or more, and even more preferably 0.55 part by weight or more. The ratio is preferably 1.5 parts by weight or less, more preferably 1.5 parts by weight 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 the compatibility of the acrylic polymer with various additive components in the adhesive layer). It is less than 1.0 parts by weight.

Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylic acid, 2-hydroxypropyl (meth)acrylic acid, 2-hydroxybutyl (meth)acrylic acid, 3-hydroxypropyl (meth)acrylic acid, and (meth)acrylic acid. 4-hydroxybutyl, 6-hydroxyhexyl (meth)acrylic acid, 8-hydroxyoctyl (meth)acrylic acid, 10-hydroxydecyl (meth)acrylic acid, 12-hydroxylauryl (meth)acrylic acid and (4- and 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 amount of the hydroxyl group-containing monomer relative to a total of 100 parts by weight of the monomer components of the acrylic base polymer is preferably 0.1 part by weight or more, more preferably 0.1 part by weight or more, from the viewpoint of introducing a crosslinked structure into the acrylic polymer and ensuring cohesion in the adhesive layer. is 0.5 parts by weight or more, and more preferably 0.8 parts by weight or more. The ratio is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, from the viewpoint of adjusting the polarity of the acrylic polymer (related to the compatibility of the acrylic polymer with various additive components in the adhesive layer).

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 amount of the carboxyl group-containing monomer relative to a total of 100 parts by weight of the monomer components of the acrylic base polymer is preferable from the viewpoints of introducing a crosslinked structure into the acrylic polymer, ensuring cohesive force in the adhesive layer, and securing adhesion to the adhesive in the adhesive layer. Preferably it is 0.1 part by weight or more, more preferably 0.5 part by weight or more, and even more preferably 0.8 part by weight or more. The ratio is preferably 30 parts by weight or less, more preferably 20 parts by weight 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 1 part by weight or more, and may be 1.5 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.

Acrylic polymers 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, solution polymerization is 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 still more preferably 500,000 or more from the viewpoint of ensuring cohesion in the adhesive layer. 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 in terms of 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 weight or more, and has a weight average molecular weight of, for example, 1,000 or more and 30,000 or less.

The adhesive composition may contain a crosslinking agent. 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 cross-linking agent, an isocyanate cross-linking agent, a peroxide cross-linking agent, and an epoxy cross-linking 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 cross-linking structure.

Isocyanate crosslinking agents include, for example, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, and tetramethyl. Examples include xylylene diisocyanate, naphthaline diisocyanate, triphenylmethane triisocyanate, and polymethylene polyphenylisocyanate. Also, examples of the isocyanate crosslinking agent include derivatives of these isocyanates. Examples of the isocyanate derivative include isocyanurate modified products and polyol modified products. Commercially available isocyanate crosslinking agents include, for example, 'Coronate L' (trimethylolpropane adduct of trilene diisocyanate, manufactured by Tosoh), 'Coronate HL' (trimethylolpropane adduct of hexamethylene diisocyanate, manufactured by Tosoh), Examples include 'Coronate HX' (isocyanurate form of hexamethylene diisocyanate, manufactured by Tosoh) and 'Takenate D110N' (trimethylolpropane adduct form of xylylene diisocyanate, manufactured by Mitsui Chemicals).

Peroxide crosslinking agents include dibenzoyl peroxide, di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, and t-butylperoxyneodecano. ate, t-hexylperoxypivalate, and t-butylperoxypivalate.

Epoxy crosslinking agents include bisphenol A, epichlorohydrin-type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, and 1,6-hexanediol glycidyl. Ether, trimethylolpropane triglycidyl ether, diglycidylaniline, diamineglycidylamine, N,N,N',N'-tetraglycidyl-m-xylylenediamine, and 1,3-bis. (N,N-diglycidylaminomethyl)cyclohexane can be mentioned.

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 components include, for example, tackifiers, plasticizers, softeners, anti-deterioration 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㎛ 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) Glass transition temperature

Dynamic viscoelasticity measurement was performed using a viscoelasticity measuring device (manufactured by TA Instruments Japan Co., Ltd., product name 'DHR') after fixing it to a jig on a parallel plate. In this measurement, the measurement mode was set to shear mode, the measurement temperature range was -50°C to 150°C, the temperature increase rate was 5°C/min, and the frequency was 1Hz. From the measurement results, the loss tangent tan δ (= loss modulus (G")/storage elastic modulus (G')) was read, and the temperature at which the loss tangent tan δ was maximized was set as the glass transition temperature of the adhesive sheet.

(3) Flexing resistance

From the polarizing plate with a retardation layer obtained in the examples and comparative examples, a sample of 100 mm It was measured using The measurement temperature was -40°C. The bending diameter (ϕ) = 3 mm, the number of bendings was 100,000, 300,000, and 500,000, and the bending direction was internal bending. Measurements were made and evaluated based on the following criteria.

Positive: No cracks or fold marks after bending test.

A: No cracks occur after the bending test, but there are fold marks.

Bad: Cracks occurred after bending test

(4) Creep value

The adhesive used in the examples and comparative examples was formed on a parallel plate to a thickness of 1 mm, and cut out into a circle with a diameter of 8 mm to serve as a measurement sample. The obtained measurement sample was supplied to a viscoelasticity measuring device (manufactured by TA Instruments Japan Co., Ltd., product name 'DHR'), a pressure of 10 kPa was applied for 10 minutes, and the maximum deformation after release without applying pressure for 10 minutes was measured. It was set as creep value (%).

(5) Amount of adhesive misalignment

A sample of 5 cm x 5 cm was cut from the polarizing plate with a retardation layer obtained in the examples and comparative examples and used as a measurement sample. For the obtained measurement sample, the amount of adhesive misalignment when bonded to a glass plate (alkali-free glass) using a roller was measured using a differential interference microscope (FPD inspection microscope 'MX63L' manufactured by Olympus), as follows. It was evaluated based on the standards. Additionally, the roller weight was set to 1 kg and the bonding speed was set to 5 cm/sec.

Amount: The amount of adhesive misalignment is less than 300㎛

Defective: Adhesive misalignment is more than 300㎛

[Preparation Example 1] Preparation 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'-azobisisobutyro as a thermal polymerization initiator. A mixture (solid concentration 47% by weight) containing 0.1 part by weight of nitrile (AIBN) and ethyl acetate as a solvent 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, 1.5 parts by weight of the first acrylic oligomer per 100 parts by weight of solid content of the polymer solution, 0.26 parts by weight of the first crosslinking agent (product name 'Niper BMT-40SV', dibenzoyl peroxide, manufactured by Nippon Yushi Co., Ltd.), and a second crosslinking agent. Add 0.02 parts by weight of cross-linking agent (brand name 'Coronate L', trimethylolpropane/trylene diisocyanate terpolymer 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 peel-treated surface of the first release liner, one of which had undergone silicone peel-off treatment, to form a coating film. The first release liner is a polyethylene terephthalate (PET) film (product name 'Diafoil MRF #75', thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) on one side of which has been subjected to a silicone release treatment. Next, the peeling-treated surface of the second peeling liner, one of which had undergone silicone peeling treatment, was bonded to the coating film on the first peeling liner. The second release liner is a PET film (product name 'Diafoil MRF #75', thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) on one side of which has been subjected to a silicone release treatment. Next, the coating film on the first release liner 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 25 μm. The obtained adhesive layer (A) was used for evaluation of (2) and (4) above. The results are shown in Table 1.

[Preparation Example 2] Preparation 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), and the prepolymer composition (polymerization rate was about 10%) ) was obtained (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. 0.3 parts by weight (manufactured by Kyoto) was mixed to prepare a photocurable adhesive composition.

3. Formation of adhesive layer (B)

The pressure-sensitive adhesive composition (B) was applied onto the peeled surface of the first release liner, one of which had undergone silicone peeling treatment, to form a coating film. The first release liner is a polyethylene terephthalate (PET) film (product name 'Diafoil MRF #75', thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) on one side of which has been subjected to a silicone release treatment. Next, the peeling-treated surface of the second peeling liner, one of which had undergone silicone peeling treatment, was bonded to the coating film on the first peeling liner. The second release liner is a PET film (product name 'Diafoil MRF #75', thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) on one side of which has been subjected to a silicone release treatment. Next, the coating film was irradiated with ultraviolet rays beyond the second release liner, and the coating film was cured 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 25 μm. The obtained adhesive layer (B) was used for evaluation of (2) and (4) above. The results are shown in Table 1.

[Preparation Example 3] Preparation 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), and a prepolymer composition (polymerization rate of about 10%) was obtained (prepolymer). The composition contains monomer components that have not undergone polymerization).

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. Preparation) 0.3 parts by weight were mixed to prepare a photocurable adhesive composition.

3. Formation of adhesive layer (C)

The pressure-sensitive adhesive composition (C) was applied onto the peel-treated surface of the first release liner, one of which had undergone silicone peel-off treatment, to form a coating film. The first release liner is a polyethylene terephthalate (PET) film (product name 'Dia Foil MRF #75', thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) on one side of which has been subjected to a silicone release treatment. Next, the peeling-treated surface of the second peeling liner, one of which had undergone silicone peeling treatment, was bonded to the coating film on the first peeling liner. The second release liner is a PET film (product name 'Diafoil MRF #75', thickness 75㎛, manufactured by Mitsubishi Chemical Corporation) on one side of which has been subjected to a silicone release treatment. Next, the coating film was irradiated with ultraviolet rays beyond the second release liner, and the coating film was cured 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. The obtained adhesive layer (C) was used for evaluation of (2) and (4) above. The results are shown in Table 1.

[Preparation Example 4] Preparation 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. The monomer mixture containing was added. 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 added together with ethyl acetate, and nitrogen gas was introduced while gently stirring to replace nitrogen. Afterwards, the polymerization reaction was performed for 7 hours while maintaining the liquid temperature in the flask around 55°C. 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/trylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Kogyo, brand name 'Coronate L') as a crosslinking agent, and a silane coupling agent (brand name: 0.2 parts by weight of KBM403 (manufactured by Shin-Etsu Chemical Co., Ltd.) was added and stirred to obtain an adhesive composition.

3. Formation of adhesive layer (D)

The acrylic adhesive composition was uniformly applied 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 using a fountain coater, and placed in an air circulation type constant temperature oven at 155°C. was dried for 2 minutes to form an adhesive layer (D) with a thickness of 15㎛. The obtained adhesive layer (D) was used for evaluation of (2) and (4) above. The results are shown in Table 1.

[Preparation Example 5] Preparation 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 added to a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas introduction tube, and condenser. In addition, with respect to 100 parts by weight of the monomer mixture, 0.1 part by weight of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator was added along with ethyl acetate, and nitrogen gas was introduced while gently stirring to replace nitrogen. , the polymerization reaction was performed for 7 hours while maintaining the liquid temperature in the flask around 55°C. After that, 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 Yushi 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 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 using a fountain coater, and placed in an air circulation type constant temperature oven at 155°C. was dried for 2 minutes to form an adhesive layer (E) with a thickness of 15㎛. The obtained adhesive layer (E) was used for evaluation of (2) and (4) above. The results are shown in Table 1.

[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 approximately 75°C was used. Corona treatment was performed on one side of the resin substrate.

100 parts by weight of PVA-based resin mixed at 9:1 with polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Kosei Chemical Co., Ltd., product name 'Kose Pymer Z410'), 13 parts by weight of potassium iodide was added and 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 (an aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (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 as much as possible (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 stretching ratio was stretched in the longitudinal direction (longitudinal direction) between rolls with different circumferential speeds of 5.5. Uniaxial stretching was performed to double the weight (underwater stretching treatment).

After that, the laminate was immersed in a washing bath (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 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 heating roll made of SUS 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 crystalline phase (manufactured by BASF, brand name 'Paliocolor LC242', expressed in the formula below), and a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF, brand name 'Irgacure 907') 3 g 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㎛) was rubbed using a rubbing cloth, and orientation treatment was performed. The direction of the orientation treatment was set to be 15° when viewed from the viewer's side with respect to the absorption axis direction 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 thus formed was irradiated with light at 1 mJ/cm ² using a metal halide lamp, and the liquid crystal layer was cured, 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 absorption axis direction 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) (25 micrometers in thickness) 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 evaluation of (3) and (5) 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 50 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 manufactured according to Procedure 1. below, and a single liquid crystal alignment layer was prepared according to Procedures 2. and 3. instead of the first liquid crystal alignment layer and the second liquid crystal alignment layer in Example 1. A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that the layer and other retardation layers were 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

An HC-TAC film was bonded to the surface of the polarizer obtained in Procedure 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 light was 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 confirming dissolution, return to room temperature, add 3 parts of ‘Irgacure 907’ (manufactured by BASF Japan Co., Ltd.), 0.2 parts of ‘Megapack F-554’ (manufactured by DIC Co., Ltd.), p. -0.1 part of methoxyphenol (MEHQ) was added and further stirred to obtain a solution. The solution was transparent and uniform. The obtained solution was filtered through a 0.20㎛ 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, and the first liquid crystal alignment solidification layer was obtained. 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 represented as a block polymer for convenience: weight average molecular weight 5000), polymerization showing a nematic liquid crystal phase 80 parts by weight of liquid crystal (manufactured by BASF, product name 'Paliocolor LC242') and 5 parts by weight of photopolymerization initiator (product name 'Irgacure 907', manufactured by Ciba Specialty Chemicals) to 200 parts by weight of cyclopentanone. It was dissolved to prepare a liquid crystal coating liquid. Then, the coating solution 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. By irradiating ultraviolet rays to this liquid crystal layer and hardening the liquid crystal layer, a second liquid crystal alignment solidification layer (thickness: 0.58 μm) was formed 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 3 except that the thickness of the adhesive layer was 50 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 1]

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 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 50 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 Example 1 except that the adhesive layer (C) obtained in Production Example 3 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 4]

A polarizing plate with a retardation layer was obtained in the same manner as in Comparative Example 3 except that the thickness of the adhesive layer was 50 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 5]

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 6]

A polarizing plate with a retardation layer was obtained in the same manner as in Comparative Example 5 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 7]

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 8]

A polarizing plate with a retardation layer was obtained in the same manner as in Comparative Example 7 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 9]

Example 3, except that a polarizer (thickness 12 ㎛) formed from a PVA-based resin film was used as the polarizer, and an inner protective layer (TAC film, 25 ㎛ thickness) was provided on the opposite side of the HC-TAC film of the polarizer. In the same manner, 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 10]

A polarizing plate with a retardation layer was obtained in the same manner as in Comparative Example 9 except that the thickness of the adhesive layer was 50 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 Table 1, according to the Examples of the present invention, it is possible to obtain a polarizing plate with a retardation layer in which the occurrence of cracks is suppressed in a flexibility test in a low-temperature environment and adhesive misalignment is suppressed. On the other hand, in the polarizing plates with a retardation layer of Comparative Examples 1 to 4, the creep value at 25°C exceeded 150%, and adhesive misalignment occurred. In addition, in the polarizing plates with a retardation layer of Comparative Examples 5 to 10, the Tg of the adhesive exceeded -40°C, so cracks occurred in a flexibility test in a low-temperature environment.

[Industrial applicability]

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

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 20 ㎛ or more and 60 ㎛ or less,
The glass transition temperature of the adhesive layer is -60 ℃ or more and -40 ℃ or less, and the creep value at 25 ℃ is 10% or more and 150% or less,
Polarizer with phase contrast layer. According to paragraph 1,
A polarizing plate with a retardation layer, wherein the total thickness from the protective layer to the retardation layer is 55 μm or less. According to claim 1 or 2,
A polarizing plate with a retardation layer, wherein the glass transition temperature of the adhesive layer is -60°C or more and -45°C or less. According to any one of claims 1 to 3,
A polarizing plate with a retardation layer having a creep value of 10% or more and 130% or less at 25°C. According to any one of claims 1 to 4,
The adhesive layer is composed of an acrylic adhesive containing an acrylic base polymer, and the acrylic base polymer contains 1 to 1 part by weight of (meth)acrylic acid C _10-20 chain alkyl ester based on a total of 100 parts by weight of the monomer component. A polarizing plate with a retardation layer containing 30 parts by weight. 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 claim 5 or 6,
A polarizing plate with a retardation layer in which the acrylic base polymer contains 0.1 parts by weight to 5 parts by weight 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 5 to 7,
A polarizing plate with a retardation layer in which the acrylic base polymer contains 0.1 parts by weight to 1.5 parts by weight of a monomer having a nitrogen atom-containing ring 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 thickness of the protective layer is 45㎛ 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,
The retardation layer has a laminate structure of an alignment-fixed layer of the first liquid crystal compound and an orientation-fixed layer of the second liquid crystal compound, the Re (550) of the alignment-fixed layer of the first liquid crystal compound is 200 nm to 300 nm, and its slow axis and the angle formed by the absorption axis of the polarizer is 10° to 20°, the Re (550) of the alignment solidification layer of the second liquid crystal compound is 100 nm to 190 nm, and the angle formed between the slow axis and the absorption axis of the polarizer is A polarizer with a retardation layer of 70°∼80°. According to any one of claims 1 to 10,
The retardation layer is a single layer of an alignment-fixed layer of a liquid crystal compound, the retardation layer has a Re (550) of 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 formed between its slow axis and the absorption axis of the polarizer is 35° to 55°. According to clause 12,
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. According to any one of claims 1 to 13,
A polarizing plate with a retardation layer, wherein the adhesive layer has a thickness of 20 μm or more.