JP2020126226A - Polarizing plate and display device - Google Patents

Abstract

To provide a circularly polarizing plate comprising a retardation film using a polymerizable liquid crystal compound and is characterized in that an in-plane retardation difference thereof before and after being exposed to a high-temperature high-humidity environment does not easily increase.SOLUTION: A circularly polarizing plate is provided, comprising a polarizing plate and a retardation film. The polarizing plate comprises a polarizer and a protective film pasted on at least one surface of the polarizer, where the polarizer is a polyvinyl alcohol resin film with iodine absorbed and aligned therein, and contains 1.00 wt.% or more of boron. The protective film has a moisture permeability of 50 g/m/24hr or greater. The retardation film comprises a retardation layer made of a cured polymerizable liquid crystal compound.SELECTED DRAWING: None

Description

The present invention relates to a polarizing plate and a display device.

In recent years, image display devices represented by organic electroluminescence (hereinafter, also referred to as organic EL) display devices have rapidly become popular. A circularly polarizing plate including a polarizer and a retardation film (λ/4 plate) is mounted on the organic EL display device. By disposing the circularly polarizing plate, reflection of external light can be prevented and the visibility of the screen can be improved.

With the rise of organic EL display devices, the demand for thinning of image display devices has become strong, and so has the need for thinning of circular polarizing plates. It has been considered to change from a conventional retardation film formed by molding a resin film to a retardation film formed by using a liquid crystal compound that can be thinned as a material (for example, refer to Patent Document 1). A retardation film using a polymerizable liquid crystal compound is produced by applying a polymerizable liquid crystal compound on a substrate for alignment, and irradiating light as necessary to fix the alignment state.

JP, 2017-54093, A

It has been found that when a circularly polarizing plate having a retardation film using a polymerizable liquid crystal compound is placed in a high temperature and high humidity environment, the in-plane retardation value of the retardation film increases. The increase of the in-plane retardation value may change the reflection hue and deteriorate the visibility of the image display device. An object of the present invention is a circularly polarizing plate provided with a retardation film using a polymerizable liquid crystal compound, wherein the in-plane retardation value of the retardation film hardly increases before and after being placed in a high temperature and high humidity environment. Is to provide.

[1] A circularly polarizing plate having a polarizing plate and a retardation film,
The polarizing plate includes a polarizer and a protective film attached to at least one surface of the polarizer,
The polarizer is a film in which iodine is adsorbed and oriented on a polyvinyl alcohol-based resin film,
The boron content of the polarizer is 1.00% by weight or more,
The moisture permeability of the protective film is 50 g/m ² ·24 hr or more,
The retardation film is a circularly polarizing plate including a retardation layer composed of a cured layer of a polymerizable liquid crystal compound.
[2] The circularly polarizing plate according to [1], wherein the thickness of the polarizer is 20 μm or less.
[3] The circularly polarizing plate according to [1] or [2], wherein the single-element transmittance of the above-mentioned polarizer for correction of visibility is 40% or more.
[4] The contraction stress in the absorption axis direction per width 2 mm is 60 N/mm ² or more when the polarizer is held at 80° C. for 4 hours, according to any one of [1] to [3]. Circular polarizing plate.
[5] The single hue of the polarizer has an a* value of −0.90 or more and −0.60 or less and a b* value of 2.70 or more and 3.70 or less. The circularly polarizing plate according to any one of the above.
[6] The retardation film includes an alignment film,
The circularly polarizing plate according to any one of [1] to [5], wherein the alignment film is located between the polarizer and the retardation layer.
[7] The circularly polarizing plate according to any one of [1] to [6], wherein the polarizing plate and the retardation film are bonded together with an active energy ray-curable adhesive.
[8] The polarizing plate includes protective films on both surfaces of the polarizer,
The water vapor transmission rate of one protective film is 500 g/m ² ·24 hr or more,
The water vapor permeability of the other protective film is 100 g/m< ² >*24 hr or less, The circularly polarizing plate in any one of [1]-[7].
[9] The circularly polarizing plate according to any one of [1] to [8], further including a front plate, a light shielding pattern, and a touch sensor.
[10] A display device including the circularly polarizing plate according to any one of [1] to [9] and a display element.

According to the present invention, a circularly polarizing plate provided with a retardation film using a polymerizable liquid crystal compound, wherein the in-plane retardation value of the retardation film hardly increases before and after being placed in a high temperature and high humidity environment. Can be provided.

It is an example of a schematic cross-sectional view showing a layer structure of a circularly polarizing plate. It is an example of a schematic cross-sectional view showing a layer structure of an organic EL display device.

<Circular polarizing plate>
The circularly polarizing plate of the present invention has a polarizing plate and a retardation film. The polarizing plate and the retardation film can be laminated via an adhesive layer, for example. Examples of the adhesive layer include a pressure-sensitive adhesive layer and an adhesive layer described later. In the present invention, the polarizing plate refers to a laminate including a polarizer and a protective film attached to at least one surface of the polarizer.

An example of the layer structure of the circularly polarizing plate of the present invention will be described below with reference to FIG. Note that, in FIG. 1, an adhesive layer for bonding the polarizer 10 and the protective films 11 and 12 to each other is not shown. In the circularly polarizing plate 100 shown in FIG. 1A, the first protective film 11 is laminated on one surface of the polarizer 10, and the second protective film 12 is laminated on the other surface of the polarizer 10. The polarizing plate 1 and the retardation film 2 including the layer 20 in which the polymerizable liquid crystal compound is cured have a layer structure in which they are laminated via an adhesive layer 13. Further, the circularly polarizing plate 100 has an adhesive layer 14 on the surface of the retardation film 2 opposite to the polarizing plate 1. The pressure-sensitive adhesive layer 14 can be a pressure-sensitive adhesive layer for bonding to an organic EL display element, a touch sensor, or the like.

In the circularly polarizing plate 101 shown in FIG. 1B, the first protective film 11 is laminated on one surface of the polarizer 10, and the second protective film 12 is laminated on the other surface of the polarizer 10. The polarizing plate 1 and the retardation film 2 have a layer structure in which the pressure-sensitive adhesive layer 13 is laminated. In the circularly polarizing plate 101, the retardation film 2 has a layer structure in which a layer 20 in which a polymerizable liquid crystal compound is cured and a layer 21 in which a polymerizable liquid crystal compound is cured are laminated via an adhesive layer 15. Further, the circularly polarizing plate 101 has an adhesive layer 14 on the surface of the retardation film 2 opposite to the polarizing plate 1. The pressure-sensitive adhesive layer 14 can be a pressure-sensitive adhesive layer for bonding to an organic EL display element, a touch sensor, or the like.

In the circularly polarizing plate 103 shown in FIG. 1C, the polarizing plate 1 in which the first protective film 11 is laminated on one surface of the polarizer 10 and the retardation film 2 have the adhesive layer 13 interposed therebetween. It has a laminated layer structure. In the circularly polarizing plate 103, the polarizing plate 1 is a polarizing plate having a protective film on only one surface of the polarizer 10. In the circularly polarizing plate 103, the retardation film 2 has a layer structure in which a layer 20 in which a polymerizable liquid crystal compound is cured and a layer 21 in which a polymerizable liquid crystal compound is cured are laminated via an adhesive layer 15. Further, the circularly polarizing plate 103 has an adhesive layer 14 on the surface of the retardation film 2 opposite to the polarizing plate 1. The pressure-sensitive adhesive layer 14 can be a pressure-sensitive adhesive layer for bonding to an organic EL display element, a touch sensor, or the like.

As shown in FIG. 1, the retardation film may have one retardation layer or two retardation layers. Further, the retardation film preferably has, in addition to the retardation layer, an orientation film for orienting the polymerizable liquid crystal compound at the manufacturing stage. As shown in FIG. 1, the polarizing plate may have the protective film laminated on only one surface of the polarizer, or may be laminated on both surfaces.

The circularly polarizing plate may have layers other than the layers shown in FIG. Examples of layers that the circularly polarizing plate may further include include a front plate, a light-shielding pattern, and a touch sensor. The front plate can be arranged on the side of the polarizing plate opposite to the side on which the retardation film is laminated.

The light-shielding pattern can be formed on the surface of the front plate on the polarizing plate side. The light-shielding pattern can be formed in the frame (non-display area) of the image display device so that the wiring of the image display device is not visible to the user.

The touch sensor is arranged on the surface of the retardation film opposite to the polarizing plate side. The touch sensor may be arranged between the front plate and the polarizing plate. The touch sensor is used as an input means.
As the touch sensor, various types such as a resistance film type, a surface acoustic wave type, an infrared type, an electromagnetic induction type, and a capacitance type have been proposed, and any type may be used. Of these, the capacitance method is preferable. The capacitive touch sensor is divided into an active region and a non-active region located outside the active region. The active region is a region corresponding to a region where the screen is displayed on the display panel (display unit), and is a region where a user's touch is sensed, and the inactive region is a region where the screen is not displayed on the display device (non-display region). It is an area corresponding to the display part). The touch sensor has a substrate having flexible characteristics; a sensing pattern formed in an active region of the substrate; formed in an inactive region of the substrate and connected to an external driving circuit through the sensing pattern and a pad unit. Each sensing line can be included. The substrate of the touch sensor preferably has a toughness of 2,000 MPa% or more from the viewpoint of suppressing cracks that may occur in the touch sensor. More preferably, the toughness is 2,000 MPa% to 30,000 MPa%. Here, toughness is defined as the area under the curve to the breaking point in the stress (MPa)-strain (%) curve (Stress-Strain Curve) obtained through the tensile test of the polymer material.

The main surface of the circularly polarizing plate may have a substantially rectangular shape. The main surface means a surface having the largest area corresponding to the display surface. The term “substantially rectangular” means that at least one corner of the four corners (corner) is cut off so that it has an obtuse angle, is rounded, or has an end face perpendicular to the main surface. Part of the main surface has a recess (notch) that is recessed in the in-plane direction, or part of the main surface has a holed part that is cut into a shape such as a circle, an ellipse, a polygon, or a combination thereof. It means that you may have.

The size of the circularly polarizing plate is not particularly limited. When the circularly polarizing plate is substantially rectangular, the length of the long side is preferably 6 cm or more and 35 cm or less, more preferably 10 cm or more and 30 cm or less, and the length of the short side is 5 cm or more and 30 cm or less. It is preferable that the distance is 6 cm or more and 25 cm or less.

<Polarizing plate>
In the present invention, the polarizing plate means that the optical plate includes a polarizer and a protective film attached to at least one surface of the polarizer. That is, the polarizing plate refers to a laminate including a polarizer and a protective film attached to one side or both sides of the polarizer. The protective film included in the polarizing plate may have a surface-treated layer such as a hard coat layer, an antireflection layer, or an antistatic layer described below. The polarizer and the protective film can be laminated via, for example, an adhesive layer or a pressure-sensitive adhesive layer. The members included in the polarizing plate will be described below.

(1) Polarizer A polarizer included in a polarizing plate absorbs linearly polarized light having a vibration plane parallel to its absorption axis and transmits linearly polarized light having a vibration plane orthogonal to the absorption axis (parallel to the transmission axis). It can be an absorption-type polarizer having properties. In the present invention, as the polarizer, a polyvinyl alcohol resin film in which iodine is adsorbed and oriented is used.

The phenomenon that the in-plane retardation value of the retardation film increases in a high temperature and high humidity environment is due to the fact that water elutes iodine (especially I ₃ ⁻ ) contained in the polarizer, and the iodine migrates to the retardation film. It has been clarified by the study of the present inventors that this is caused. Therefore, when the polarizer is a polyvinyl alcohol-based resin film in which iodine is adsorbed and oriented as in the present invention, it is easy to obtain the effect that the retardation value does not easily increase in a high temperature and high humidity environment.

In order to prevent the elution of iodine in a high temperature and high humidity environment, it is preferable to increase the crosslink density of the polarizer. As described below, a polarizer is manufactured through a step of immersing a polyvinyl alcohol-based resin film in an aqueous boric acid solution, and boric acid cross-links the polyvinyl alcohol-based resin chains. When the crosslink density of the polarizer is high, iodine can be easily retained in the polarizer even in a wet heat environment. Since the crosslink density of the polarizer is considered to be related to the boron content in the polarizer, in the present invention, the boron content of the polarizer is 1.00% by weight or more and 1.80% by weight or more. The amount is preferably 2.00% by weight or more, more preferably 2.50% by weight or more. The upper limit is not particularly limited, but the boron content of the polarizer may be 10.00% by weight or less, 8.00% by weight or less, or 6.00% by weight or less. May be. The boron content of the polarizer is measured by the method described in Examples below.

In other words, it is preferable to increase the shrinkage stress of the polarizer in order to prevent the elution of iodine in a high temperature and high humidity environment. This is because the shrinkage stress of the polarizer reflects the degree of crosslinking with boric acid. When the polarizer is held at 80° C. for 4 hours, the contraction stress in the absorption axis direction per width of 2 mm is preferably 60 N/mm ² or more, more preferably 80 N/mm ² or more, and 85 N/mm More preferably, it is ² or more. The upper limit value is not particularly limited, contractile force of the polarizer may also be 120 N / mm ² or less, it may be 110N / mm ² or less. The contraction force of the polarizer is specifically measured by the method described in Examples below. The boron content and shrinkage stress can be controlled by, for example, stretching treatment or crosslinking treatment.

The polarizer is, for example, a step of uniaxially stretching a polyvinyl alcohol-based resin film; a step of adsorbing iodine by dyeing the polyvinyl alcohol-based resin film with iodine; a polyvinyl alcohol-based resin film on which iodine is adsorbed, a boric acid aqueous solution, etc. Can be produced by a method including a step of treating the polyvinyl alcohol resin film with a metal ion; and a step of washing the polyvinyl alcohol resin film with water.

As the polyvinyl alcohol resin, saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group.

In the present specification, “(meth)acrylic” means at least one selected from acrylic and methacrylic. The same applies to “(meth)acryloyl”, “(meth)acrylate” and the like.

The saponification degree of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The average degree of polymerization of the polyvinyl alcohol-based resin is usually 1000 to 10000, preferably 1500 to 5000. The average degree of polymerization of the polyvinyl alcohol resin can be determined according to JIS K 6726.

A film produced from such a polyvinyl alcohol-based resin is used as a raw film for a polarizer. The method for forming the polyvinyl alcohol-based resin into a film is not particularly limited, and a known method is adopted. The thickness of the polyvinyl alcohol-based raw film is not particularly limited, but in order to make the thickness of the polarizer 15 μm or less, it is preferable to use a film having a thickness of 5-35 μm. More preferably, it is 20 μm or less.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing with iodine, simultaneously with dyeing, or after dyeing. When the uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before or during the crosslinking treatment. In addition, uniaxial stretching may be performed at these plural stages.

In the uniaxial stretching, stretching may be uniaxial between rolls having different peripheral speeds, or uniaxial stretching may be performed using hot rolls. The uniaxial stretching may be dry stretching in which the stretching is performed in the atmosphere, or wet stretching in which the polyvinyl alcohol resin film is swollen with a solvent or water. The draw ratio is usually 3 to 8 times.

As a method of dyeing a polyvinyl alcohol-based resin film with iodine, for example, a method of immersing the film in an aqueous solution containing iodine is adopted. The polyvinyl alcohol-based resin film is preferably immersed in water before the dyeing treatment.

As the crosslinking treatment after dyeing with iodine, a method of immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution is usually adopted. The boric acid-containing aqueous solution preferably contains potassium iodide.

The boric acid concentration of the boric acid-containing aqueous solution is preferably 1.0 to 8.0 parts by weight, more preferably 1.5 to 6.0 parts by weight, and preferably 2. 0 to 100 parts by weight of water. It is more preferably 0 to 5.5 parts by weight or less. The potassium iodide concentration of the boric acid-containing aqueous solution is preferably 0.1 to 20 parts by weight, and more preferably 1.0 to 15 parts by weight with respect to 100 parts by weight of water. When the concentration of boric acid is increased, it is easy to increase the boron content.

The temperature of the boric acid-containing aqueous solution is preferably 40 to 80°C, and more preferably 60 to 70°C. If the temperature is raised, the crosslinking reaction will easily proceed. The crosslinking treatment time is preferably 1 second to 10 minutes, and more preferably 10 seconds to 5 minutes.

The cross-linking treatment may be performed once, or may be performed in plural times. When the cross-linking treatment is performed in plural times, in each cross-linking treatment, the boric acid concentration, the potassium iodide concentration, the temperature of the boric acid-containing aqueous solution, and the cross-linking treatment time may be the same or different. Good.

The metal ion treatment can be performed by immersing the polyvinyl alcohol resin film in an aqueous solution containing a metal salt. By the metal ion treatment, various metal ions can be contained in the polyvinyl alcohol resin film. As the metal ion, a metal ion of a transition metal such as cobalt, nickel, zinc, chromium, aluminum, copper, manganese, or iron is particularly preferable from the viewpoint of adjusting color tone and imparting durability. Among these metal ions, zinc ions are preferable from the viewpoint of color tone adjustment and heat resistance impartation. Examples of the zinc salt include zinc halides such as zinc chloride and zinc iodide, zinc sulfate and zinc acetate.

The concentration of zinc ions in the aqueous zinc salt solution is, for example, 0.1 to 10% by weight, preferably 0.5 to 7% by weight. Further, the zinc salt solution preferably contains potassium ion such as potassium iodide and iodide ion. The potassium iodide concentration in the zinc salt solution is, for example, 0.1 to 10% by weight, preferably 0.2 to 5% by weight.

The zinc content in the polarizer is preferably 2.00% by weight or less, more preferably 1.00% by weight or less, preferably 0.03% by weight or more, and 0.05% by weight. % Or more is more preferable. When the zinc content of the polarizer is in the above range, it is easy to prevent the elution of iodine in a high temperature and high humidity environment. The zinc content is measured using a commercially available fluorescent X-ray analyzer. The zinc content can be controlled by metal ion treatment or the like.

The iodine content in the polarizer is preferably 3.3% by weight or less, more preferably 3.0% by weight or less, more preferably 1.9% by weight or more, and 2.2% by weight. % Or more is more preferable. When the iodine content of the polarizer is in the above range, the amount of iodine that can be eluted can be reduced while maintaining good polarization performance. The iodine content is measured using a commercially available X-ray fluorescence analyzer. The iodine content can be controlled by dyeing treatment, crosslinking treatment, water washing treatment, or the like.

The thickness of the polarizer is preferably 20 μm or less, more preferably 15 μm or less, further preferably 10 μm or less, and particularly preferably 8 μm or less. The thickness of the polarizer is usually 2 μm or more, preferably 3 μm or more. Since reducing the thickness of the polarizer contributes to reducing the amount of iodine contained in the polarizer, the amount of iodine that can be eluted can be reduced. On the other hand, by ensuring a certain thickness, it is possible to improve the transportability of the film and ensure the polarization performance of the obtained polarizer.

In the thus obtained polarizer, the luminosity correction simple substance transmittance is preferably 50% or less, more preferably 45% or less, more preferably 40% or more, and 42% or more. Is more preferable. When the luminosity-corrected single transmittance of the polarizer is in the above range, the amount of iodine that can be eluted can be reduced while maintaining good polarization performance.

The polarizer thus obtained has a visibility correction polarization degree of preferably 99.999% or less, more preferably 99.995% or less, and preferably 99.985% or more, It is more preferably 99.990% or more. When the visibility-corrected polarization degree of the polarizer is in the above range, the amount of iodine that can be eluted can be reduced while maintaining good polarization performance.

The single hue of the thus obtained polarizer preferably has an a* value of −0.90 or more and −0.60 or less, and more preferably −0.88 or more and −0.65 or less. The b* value is 2.70 or more and 3.70 or less, and more preferably 2.80 or more and 3.60 or less. When the single hue of the polarizer is closer to blue, that is, when the b* value is small, the retardation value of the retardation film tends to increase in a moist heat environment, so that the effect of the present invention is remarkable. The hue of the polarizer can be measured by a commercially available spectrocolorimeter.

(2) Protective Film The circularly polarizing plate of the present invention preferably has a protective film on at least one surface of the polarizer and a protective film on the surface of the polarizer opposite to the retardation film side. The polarizing plate includes at least one protective film having a moisture permeability of 50 g/m ² ·24 hr or more. The moisture permeability of the protective film is measured by the method described below.

The protective film laminated on the polarizer can be a translucent (preferably optically transparent) thermoplastic resin. Examples of the protective film include polyolefin resins such as chain polyolefin resins (polypropylene resins) and cyclic polyolefin resins (norbornene resins); cellulose resins such as triacetyl cellulose and diacetyl cellulose; polyethylene terephthalate, Polyester resin such as polybutylene terephthalate; polycarbonate resin; (meth)acrylic resin such as methyl methacrylate resin; polystyrene resin; polyvinyl chloride resin; acrylonitrile-butadiene-styrene resin; acrylonitrile-styrene -Based resin; polyvinyl acetate-based resin; polyvinylidene chloride-based resin; polyamide-based resin; polyacetal-based resin; modified polyphenylene ether-based resin; polysulfone-based resin; polyethersulfone-based resin; polyarylate-based resin; polyamide-imide-based resin; polyimide A film made of a system resin or the like can be used.

As the chain polyolefin resin, polyethylene resin (polyethylene resin which is a homopolymer of ethylene or a copolymer mainly composed of ethylene), polypropylene resin (a polypropylene resin which is a homopolymer of propylene or propylene is mainly used) In addition to a chain olefin homopolymer such as a copolymer), a copolymer composed of two or more kinds of chain olefins can be mentioned.

Cyclic polyolefin resin is a general term for resins polymerized with cyclic olefin as a polymerized unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples of the cyclic polyolefin resin include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins with chain olefins such as ethylene and propylene (typically Are random copolymers), graft polymers obtained by modifying these with unsaturated carboxylic acids and their derivatives, and their hydrides. Above all, a norbornene-based resin using a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer as the cyclic olefin is preferably used.

The polyester-based resin is a resin having an ester bond except the following cellulose ester-based resin, and is generally composed of a polycondensate of a polyvalent carboxylic acid or its derivative and a polyhydric alcohol. As the polyvalent carboxylic acid or its derivative, a divalent dicarboxylic acid or its derivative can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. A divalent diol can be used as the polyhydric alcohol, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. A typical example of the polyester resin is polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol.

The (meth)acrylic resin is a resin containing a compound having a (meth)acryloyl group as a main constituent monomer. Specific examples of the (meth)acrylic resin include, for example, poly(meth)acrylic acid ester such as polymethylmethacrylate; methylmethacrylate-(meth)acrylic acid copolymer; methylmethacrylate-(meth)acrylic acid. Ester copolymer; methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymer; methyl (meth)acrylate-styrene copolymer (MS resin etc.); methyl methacrylate and alicyclic hydrocarbon group It includes a copolymer with a compound having (for example, a methyl methacrylate-cyclohexyl methacrylate copolymer, a methyl methacrylate-norbornyl (meth)acrylate copolymer, etc.). Preferably, a polymer having poly(meth)acrylic acid C _1-6 alkyl ester as a main component such as methyl poly(meth)acrylate is used, and more preferably, methyl methacrylate is a main component (50 to 100). % By weight, preferably 70 to 100% by weight) is used.

The cellulose ester-based resin is an ester of cellulose and fatty acid. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Moreover, these copolymers and those in which a part of the hydroxyl groups are modified with other substituents are also included. Among these, cellulose triacetate (triacetyl cellulose) is particularly preferable.

Polycarbonate resin is an engineering plastic composed of a polymer in which monomer units are bonded via a carbonate group.

The thickness of the protective film is usually 1 to 100 μm, but from the viewpoint of strength and handleability, it is preferably 5 to 60 μm, more preferably 10 to 55 μm, and further preferably 15 to 40 μm.

The protective film attached to one side or both sides of the polarizer may be made of the same kind of thermoplastic resin or different kinds of thermoplastic resins. The thickness may be the same or different. Further, they may have the same phase difference characteristic or different phase difference characteristics.

In the high temperature and high humidity environment as described above, the phenomenon that the in-plane retardation value of the retardation film increases, water elutes iodine contained in the polarizer, and the iodine is caused by migration to the retardation film. It is considered to be something. Therefore, in a high temperature and high humidity environment, the effect of the present invention is remarkable when water easily enters the polarizer and when iodine is easily eluted from the polarizer. Examples of such a mode include a mode in which a protective film having high moisture permeability is laminated on the side opposite to the retardation film side of the polarizer, and a mode in which the protective film is not laminated on the retardation film side of the polarizer.

From such a viewpoint, the water vapor permeability of the protective film provided on the side opposite to the retardation film side of the polarizing plate may be 50 g/m ² ·24 hr or more, or 100 g/m ² ·24 hr or more. Or may be 500 g/m ² ·24 hr or more. The moisture permeability of the protective film can be, for example, 1000 g/m ² ·24 hr or less. The moisture vapor transmission rate is based on JIS Z 0208, and means a value measured at a temperature of 40° C. and a relative humidity of 90%.

When the polarizing plate includes protective films on both surfaces of the polarizer, the moisture permeability of one protective film is 50 g/m ² ·24 hr or more (or 100 g/m ² ·24 hr or more, further 500 g/m ² · 24 hr or more), the moisture permeability of the other protective film is preferably 1000 g/m ² ·24 hr or less, more preferably 500 g/m ² ·24 hr or less, and 100 g/m ² · It is more preferably 24 hours or less, and particularly preferably 50 g/m ² ·24 hours or less.

When the polarizing plate has protective films on both surfaces of the polarizer, the moisture permeability of the protective film arranged on the side opposite to the retardation film side of the polarizer is 50 g/m ² ·24 hr or more (or 100 g/m ²・24 hr or more, further 500 g/m ² ·24 hr or more), the moisture permeability of the protective film disposed on the retardation film side of the polarizer is preferably 1000 g/m ² ·24 hr or less, 500 g /M ² ·24 hr or less is more preferable, 100 g/m ² ·24 hr or less is further preferable, and 50 g/m ² ·24 hr or less is particularly preferable.

As described above, at least one of the protective films has a hard coat layer, an antiglare layer, a light diffusing layer, an antireflection layer, a low refractive index layer, an electrostatic charge on its outer surface (the surface opposite to the polarizer). It may be provided with a surface treatment layer (coating layer) such as an antifouling layer and an antifouling layer. The thickness of the protective film includes the thickness of the surface treatment layer. These surface-treated layers can contribute to prevent moisture from entering the polarizer.

The protective film can be attached to the polarizer via an adhesive layer or a pressure-sensitive adhesive layer described below. The adhesive forming the adhesive layer is preferably a water-based adhesive or an active energy ray curable adhesive.

When laminating the polarizer and the protective film, a surface activation treatment may be performed on at least one of the laminating surfaces in order to enhance the adhesiveness. As surface activation treatment, dry treatment such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, ionizing actinic ray treatment (ultraviolet treatment, electron beam treatment, etc.) A wet treatment such as ultrasonic treatment using a solvent such as water or acetone, saponification treatment, anchor coating treatment; These surface activation treatments may be performed alone or in combination of two or more.

When the protective films are attached to both surfaces of the polarizer, the adhesive for attaching the protective films may be the same kind of adhesive or different kinds of adhesives.

Instead of the protective film, a protective layer may be formed on at least one surface of the polarizer. The protective layer can be formed on the polarizer without interposing an adhesive layer or a pressure-sensitive adhesive layer, that is, the protective layer can be formed in contact with the polarizer. The protective layer can be a layer containing a (meth)acrylic resin. The protective layer may prevent migration of iodine from the polarizer. The protective layer may be a single layer or a plurality of layers.

The layer containing a (meth)acrylic resin is applied to a polarizer by applying a composition containing a (meth)acrylic resin, and is heated or irradiated with an active energy ray, or a (meth)acrylic resin is provided on a base film. It can be formed by applying a composition containing the above and heating or irradiating with an active energy ray. In the latter case, the polarizer may be formed on the layer containing the (meth)acrylic resin.

The (meth)acrylic resin means a polymer whose main component is a monomer having a (meth)acryloyl group among the monomers constituting the (meth)acrylic resin. Here, the main component means a monomer having the largest content (mass %) among the monomer components constituting the (meth)acrylic resin. By using the (meth)acrylic resin as the material for forming the protective layer, it is possible to suppress the deterioration of the optical characteristics of the circularly polarizing plate even in a wet heat environment.

The (meth)acrylic resin is preferably a polymer of a photopolymerizable monomer. For example, a monofunctional monomer or a polyfunctional monomer having a (meth)acryloyl group is used alone or in combination of two or more. It can be The (meth)acrylic resin may be polymerized with a monomer other than the monomer having a (meth)acryloyl group, for example, a monomer having a vinyl group may be polymerized.

The monomer having a (meth)acryloyl group is not particularly limited, and examples thereof include compounds having one or more (meth)acryloyl groups in the molecule, and these may be used alone or in combination of two or more. Can be used. Specifically, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ethylene oxide or propylene oxide of the above (meth)acrylate. Additive compound; oligoester (meth)acrylate having four or more (meth)acryloyl groups in the molecule, oligoether (meth)acrylate, oligourethane (meth)acrylate, oligoepoxy (meth)acrylate, oligomelamine (meth) Examples thereof include acrylates and polyfunctional acrylates having a dendrimer structure.

The thickness of the layer containing the (meth)acrylic resin is usually 0.1 μm or more, preferably 0.3 μm or more, more preferably 0.5 μm or more, and usually 20.0 μm or less. It is preferably 15 μm or less, more preferably 10 μm or less.

<Retardation film>
The circularly polarizing plate of the present invention has a retardation film. The retardation film has a retardation layer.
The retardation layer preferably has a layer composed of a composition containing a polymerizable liquid crystal compound.
The layer composed of the composition containing the polymerizable liquid crystal compound specifically means a layer obtained by curing the polymerizable liquid crystal compound. In this specification, a layer that gives a retardation of λ/2, a layer that gives a retardation of λ/4 (a positive A layer), a positive C layer, and the like may be collectively referred to as a retardation layer. Furthermore, it is preferable that the retardation film includes an alignment film described below.

The layer giving a retardation of λ/2 means a layer having an in-plane retardation value of 200 to 280 nm at a wavelength of 550 nm, and more preferably a layer having an in-plane retardation value of 215 to 265 nm. Means that. The layer giving a retardation of λ/4 means a layer having an in-plane retardation value of 100 to 160 nm at a wavelength of 550 nm, and more preferably a layer having an in-plane retardation value of 110 to 150 nm. Means that. The positive C layer can be a layer in which the refractive index has a relationship of nx≈ny<nz. The retardation value in the thickness direction of the positive C layer can be -50 nm to -150 nm at a wavelength of 550 nm, and can be -70 nm to -120 nm. Note that nx is the refractive index in the direction in which the in-plane refractive index is maximum (that is, the slow axis direction), and ny is the refractive index in the direction orthogonal to the slow axis (that is, the fast axis direction). And nz is the refractive index in the thickness direction.

The retardation layer may exhibit positive wavelength dispersion or reverse wavelength dispersion. When the retardation film has a plurality of retardation layers, each retardation layer may exhibit positive wavelength dispersion or reverse wavelength dispersion. When the retardation film is provided with a retardation layer exhibiting reverse wavelength dispersion, when the retardation value rises in a wet heat environment, the reflected hue is likely to change and the visibility of the display device is likely to deteriorate. Therefore, the effect of the present invention is remarkable when the retardation film has a retardation layer exhibiting reverse wavelength dispersion.

In the present invention, it is preferable that the layer that gives a retardation of λ/4 has reverse wavelength dispersion.
Specifically, the layer that gives a retardation of λ/4 preferably satisfies the following formula.
0.80<Re(450)/Re(550)<1.00 (1)
1.00<Re(650)/Re(550)<1.30 (2)
In the formula, Re(λ) represents the in-plane retardation value at the wavelength λnm.

The layer in which the polymerizable liquid crystal compound is cured is formed, for example, on the alignment film provided on the base material. The base material has a function of supporting the alignment film and may be a long base material. This base material functions as a releasable support and can support a retardation layer for transfer. Further, it is preferable that the surface thereof has an adhesive strength such that it can be peeled off. Examples of the base material include the resin films exemplified as the material of the protective film.

The thickness of the substrate is not particularly limited, but is preferably in the range of 20 μm or more and 200 μm or less, for example. When the thickness of the base material is 20 μm or more, strength is imparted. On the other hand, when the thickness is 200 μm or less, it is possible to suppress an increase in processing waste and abrasion of the cutting blade when cutting the base material into a single-piece base material.

The base material may be subjected to various antiblocking treatments. Examples of the blocking prevention treatment include an easy adhesion treatment, a treatment of kneading a filler and the like, an embossing treatment (knurling treatment) and the like. By subjecting the substrate to such a blocking prevention treatment, it is possible to effectively prevent sticking between the substrates when winding the substrate, so-called blocking, and to produce an optical film with high productivity. Is possible.

The layer in which the polymerizable liquid crystal compound is cured is formed on the substrate via the alignment film. That is, the base material and the alignment film are laminated in this order, and the layer in which the polymerizable liquid crystal compound is cured is laminated on the alignment film.

The alignment film may be a vertical alignment film, an alignment film that horizontally aligns the molecular axes of the polymerizable liquid crystal compound, or an alignment film that tilts the molecular axes of the polymerizable liquid crystal compound. Good. The type of alignment film can be selected according to the polymerizable liquid crystal compound and the required retardation characteristics. As the alignment film, one having solvent resistance that does not dissolve due to coating of a composition containing a polymerizable liquid crystal compound described later, etc., and also having heat resistance in heat treatment for removal of the solvent or alignment of the liquid crystal compound is used. preferable. Examples of the alignment film include an alignment film containing an alignment polymer, a photo-alignment film, and a glob alignment film for forming an uneven pattern or a plurality of grooves on the surface for alignment.

The thickness of the alignment film is usually in the range of 10 nm to 10000 nm, preferably in the range of 10 nm to 1000 nm, more preferably 500 nm or less, and further preferably 10 nm to 200 nm. When the retardation film includes an alignment film and the alignment film is arranged between the polarizer and the phase difference layer, the alignment film can exhibit a function of blocking migration of iodine.
The thickness of the alignment film for sufficiently exhibiting the function of blocking migration of iodine is, for example, 0.3 μm or more, preferably 0.5 μm or more, more preferably 0.7 μm or more, and further preferably Is 1.0 μm or more.

An alignment film containing an oriented polymer is usually formed by applying a composition in which an oriented polymer is dissolved in a solvent to a substrate and removing the solvent, or by applying an oriented polymer composition to the substrate and removing the solvent. Then, it is obtained by rubbing (rubbing method). As the oriented polymer, for example, polyamides or gelatins having an amide bond in the molecule, polyimide having an imide bond in the molecule and polyamic acid which is a hydrolyzate thereof, polyvinyl alcohol, alkyl modified polyvinyl alcohol, polyacrylamide, poly Examples include oxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid and polyacrylic acid esters. Of these, polyvinyl alcohol is preferable. The oriented polymer may be used alone or in combination of two or more kinds.

The photo-alignment film is usually obtained by applying a composition containing a polymer or monomer having a photoreactive group and a solvent to a substrate, irradiating polarized light (preferably polarized UV) after removing the solvent. The photo-alignment film is also advantageous in that the direction of the alignment regulating force can be arbitrarily controlled by selecting the polarization direction of the polarized light to be irradiated.

The photoreactive group refers to a group which produces a liquid crystal aligning ability when irradiated with light. Specific examples thereof include a group involved in a photoreaction which is a source of liquid crystal alignment ability such as orientation induction or isomerization reaction of molecules generated by light irradiation, dimerization reaction, photocrosslinking reaction or photodecomposition reaction. Among them, a group involved in the dimerization reaction or the photocrosslinking reaction is preferable because of excellent orientation. As the photoreactive group, a group having an unsaturated bond, particularly a double bond, is preferable, and a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond. A group having at least one selected from the group consisting of a heavy bond (N=N bond) and a carbon-oxygen double bond (C=O bond) is particularly preferable.

Examples of the photoreactive group having a C=C bond include a vinyl group, a polyene group, a stilbene group, a stilbazol group, a stilbazolium group, a chalcone group and a cinnamoyl group. Examples of the photoreactive group having a C=N bond include groups having a structure such as an aromatic Schiff base and an aromatic hydrazone. Examples of the photoreactive group having an N=N bond include an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a bisazo group, a formazan group, and a group having an azoxybenzene structure. Examples of the photoreactive group having a C=O bond include a benzophenone group, a coumarin group, an anthraquinone group and a maleimide group. These groups may have a substituent such as an alkyl group, an alkoxy group, an aryl group, an allyloxy group, a cyano group, an alkoxycarbonyl group, a hydroxyl group, a sulfonic acid group and a halogenated alkyl group.

Among them, a photoreactive group involved in the photodimerization reaction is preferable, and the amount of polarized light irradiation required for photoalignment is relatively small, and in that a photoalignment film excellent in thermal stability and stability over time is easily obtained, Cinnamoyl and chalcone groups are preferred. As the polymer having a photoreactive group, a polymer having a cinnamoyl group such that the end portion of the side chain of the polymer has a cinnamic acid structure is particularly preferable.

The polymerizable liquid crystal compound can be classified into a rod-shaped type (rod-shaped liquid crystal compound) and a disc-shaped type (disc-shaped liquid crystal compound, discotic liquid crystal compound) based on its shape. Further, there are a low molecular type and a high molecular type, respectively. The term "polymer" generally means a polymer having a degree of polymerization of 100 or more (polymer physics/phase transition dynamics, Masao Doi, page 2, Iwanami Shoten, 1992). In the present invention, any type of polymerizable liquid crystal compound can be used. You may use 2 or more types of rod-shaped liquid crystal compounds, 2 or more types of discotic liquid crystal compounds, or a mixture of a rod-shaped liquid crystal compound and a discotic liquid crystal compound.

As the rod-shaped liquid crystal compound, for example, the one described in claim 1 of JP-A-11-513019 or the paragraphs [0026] to [0098] of JP-A-2005-289980 can be preferably used. .. As the discotic liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP2007-108732A, or paragraphs [0013] to [0108] of JP2010-244038A are suitable. Can be used for.

Two or more polymerizable liquid crystal compounds may be used in combination. In that case, at least one kind preferably has two or more polymerizable groups in the molecule. That is, the layer in which the polymerizable liquid crystal compound is cured is preferably a layer formed by fixing the liquid crystal compound having a polymerizable group by polymerization. In this case, it is no longer necessary to exhibit liquid crystallinity after forming a layer.

The polymerizable liquid crystal compound has a polymerizable group capable of undergoing a polymerization reaction. As the polymerizable group, for example, a functional group capable of addition polymerization reaction such as a polymerizable ethylenically unsaturated group or a ring-polymerizable group is preferable.
More specifically, examples of the polymerizable group include a (meth)acryloyl group, a vinyl group, a styryl group, and an allyl group. Of these, a (meth)acryloyl group is preferable.

The layer in which the polymerizable liquid crystal compound is cured can be formed by coating a composition containing the polymerizable liquid crystal compound on, for example, an alignment film and irradiating with active energy rays. The composition may contain components other than the above-mentioned polymerizable liquid crystal compound. The composition preferably contains a polymerization initiator. As the polymerization initiator to be used, for example, a thermal polymerization initiator or a photopolymerization initiator is selected according to the type of polymerization reaction. Examples of the photopolymerization initiator include an α-carbonyl compound, an acyloin ether, an α-hydrocarbon-substituted aromatic acyloin compound, a polynuclear quinone compound, and a combination of a triarylimidazole dimer and p-aminophenyl ketone. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, and more preferably 0.5 to 5% by mass, based on the total solid content in the composition.

The composition may include a polymerizable monomer from the viewpoint of uniformity of the coating film and strength of the film. Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Among them, polyfunctional radically polymerizable monomers are preferable.

As the polymerizable monomer, those which can be copolymerized with the above-mentioned polymerizable liquid crystal compound are preferable. The amount of the polymerizable monomer used is preferably 1 to 50% by mass, and more preferably 2 to 30% by mass, based on the total mass of the polymerizable liquid crystal compound.

The composition may include a surfactant from the viewpoint of uniformity of the coating film and strength of the film.
Examples of the surfactant include conventionally known compounds. Of these, fluorine compounds are particularly preferable.

The composition may include a solvent, preferably an organic solvent. Examples of the organic solvent include amides (eg, N,N-dimethylformamide), sulfoxides (eg, dimethylsulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, chloroform). , Dichloromethane), esters (eg, methyl acetate, ethyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Of these, alkyl halides and ketones are preferable. The composition may include two or more organic solvents.

The composition includes a vertical alignment promoter such as a polarizer interface side vertical alignment agent and an air interface side vertical alignment agent, and a horizontal alignment promoter such as a polarizer interface side horizontal alignment agent and an air interface side horizontal alignment agent. An aligning agent can be included. Further, the composition may contain an adhesion improver, a plasticizer and a polymer in addition to the above components.

The active energy rays include ultraviolet rays, visible light, electron rays and X-rays, and preferably ultraviolet rays. The light source of the active energy rays, for example, low-pressure mercury lamp, medium-pressure mercury lamp, high-pressure mercury lamp, ultra-high pressure mercury lamp, xenon lamp, halogen lamp, carbon arc lamp, tungsten lamp, gallium lamp, excimer laser, wavelength range Examples thereof include an LED light source emitting 380 to 440 nm, a chemical lamp, a black light lamp, a microwave excited mercury lamp, and a metal halide lamp.

The irradiation intensity of ultraviolet light is, for example, ^{100mW / cm 2 ~3,000mW / cm 2} . The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating the cationic polymerization initiator or the radical polymerization initiator. The UV irradiation time is usually 0.1 seconds to 10 minutes, preferably 0.1 seconds to 5 minutes, more preferably 0.1 seconds to 3 minutes, and further preferably 0.1 seconds. ~ 1 minute. Ultraviolet rays can be irradiated once or in a plurality of times.

In the present embodiment, the thickness of the retardation layer is preferably 0.5 μm or more. The thickness of the retardation layer is preferably 10 μm or less, more preferably 5 μm or less. The upper limit value and the lower limit value described above can be arbitrarily combined. When the thickness of the retardation layer is at least the above lower limit, sufficient durability can be obtained. When the thickness of the retardation layer is not more than the above upper limit value, it can contribute to the thinning of the circularly polarizing plate. Regarding the thickness of the retardation layer, a desired in-plane retardation value of the layer giving a retardation of λ/4, a layer giving a retardation of λ/2, or a positive C layer, and a retardation value in the thickness direction can be obtained. Can be adjusted.

The retardation film may include one layer in which the polymerizable liquid crystal compound has been cured, or may include two or more layers in which the polymerizable liquid crystal compound has been cured. When the retardation film includes two layers in which the polymerizable liquid crystal compound is cured, the two layers are a layer that gives a retardation of λ/4 and a positive C layer, or a layer that gives a retardation of λ/4 and λ/2. It is preferably a layer that gives a retardation of In the case where the retardation film includes two layers in which the polymerizable liquid crystal compound is cured, a layer in which the polymerizable liquid crystal compound is cured is prepared on each of the alignment films, and the two layers are laminated with an adhesive layer interposed therebetween to obtain a retardation film. The film may be produced or a layer in which the polymerizable liquid crystal compound is further cured may be formed on the layer in which the polymerizable liquid crystal compound is cured. After laminating both, the base material can be peeled off leaving the alignment film, or both the alignment film and the base material can be peeled off.

From the viewpoint of preventing migration of iodine, it is preferable to have an alignment film between the layer in which the polymerizable liquid crystal compound is cured and the polarizer. The alignment film can also have a function of preventing iodine from entering the layer in which the polymerizable liquid crystal compound is cured. Therefore, when the retardation film includes one layer in which the polymerizable liquid crystal compound is cured, the retardation film is formed by laminating the alignment film and the layer in which the polymerizable liquid crystal compound is cured in this order from the side closer to the polarizer. It is preferable that the structure is When the retardation film includes two layers in which the polymerizable liquid crystal compound is cured, the retardation film is an alignment film, a layer in which the polymerizable liquid crystal compound is cured, an adhesive layer, and a polymerizable liquid crystal compound from the side close to the polarizer. Cured layer, and a configuration in which the alignment film is laminated in this order, from the side close to the polarizer, the alignment film, the layer cured by the polymerizable liquid crystal compound, the alignment film, and the layer cured by the polymerizable liquid crystal compound is It is preferable that the layers are laminated in order.

The thickness of the retardation film is preferably 3 to 30 μm, more preferably 5 to 25 μm.

<Adhesive layer>
Examples of the adhesive layer include a pressure-sensitive adhesive layer and an adhesive layer described later. The adhesive layer is formed by laminating a polarizer and a protective film, laminating a polarizing plate and a retardation film, laminating two retardation layers, laminating a circularly polarizing plate on an image display device or a touch sensor. It can be a layer for doing.

From the viewpoint of preventing migration of iodine, the adhesive layer for laminating the polarizing plate and the retardation film is preferably an adhesive layer, and more preferably an active energy ray-curable adhesive layer. The thickness of the adhesive layer for laminating the polarizing plate and the retardation film is preferably 1.0 μm or more, more preferably 1.5 μm or more, still more preferably 2.0 μm or more.

<Adhesive layer>
The pressure-sensitive adhesive layer can be composed of a pressure-sensitive adhesive composition containing a resin such as (meth)acrylic, rubber-based, urethane-based, ester-based, silicone-based, or polyvinyl ether-based resin as a main component.
Above all, a pressure-sensitive adhesive composition containing a (meth)acrylic resin as a base polymer, which is excellent in transparency, weather resistance, heat resistance, etc., is preferable. The pressure-sensitive adhesive composition may be an active energy ray curable type or a thermosetting type. The thickness of the pressure-sensitive adhesive layer is usually 3 to 30 μm, preferably 3 to 25 μm.

Examples of the (meth)acrylic resin (base polymer) used in the pressure-sensitive adhesive composition include butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and (meth)acrylic acid 2- A polymer or copolymer having one or more kinds of (meth)acrylic acid ester such as ethylhexyl as a monomer is preferably used. It is preferable to copolymerize a polar monomer with the base polymer. As the polar monomer, for example, (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, glycidyl ( Examples thereof include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group and the like such as (meth)acrylate.

The pressure-sensitive adhesive composition may contain only the above base polymer, but usually further contains a crosslinking agent. As the cross-linking agent, a metal ion having a valence of 2 or more and forming a carboxylic acid metal salt with a carboxyl group; a polyamine compound forming an amide bond with a carboxyl group; Examples thereof include epoxy compounds and polyols that form an ester bond with a carboxyl group; and polyisocyanate compounds that form an amide bond with a carboxyl group. Of these, polyisocyanate compounds are preferable.

<Adhesive layer>
Examples of the water-based adhesive include an adhesive composed of a polyvinyl alcohol-based resin aqueous solution and a water-based two-component urethane-based emulsion adhesive. Above all, a water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution is preferably used. Examples of the polyvinyl alcohol-based resin include a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and another monomer copolymerizable therewith. A polyvinyl alcohol-based copolymer obtained by saponifying a polymer, a modified polyvinyl alcohol-based polymer obtained by partially modifying the hydroxyl groups of these, or the like can be used. The water-based adhesive may contain a crosslinking agent such as an aldehyde compound (glyoxal or the like), an epoxy compound, a melamine compound, a methylol compound, an isocyanate compound, an amine compound, a polyvalent metal salt or the like.

When a water-based adhesive is used, it is preferable to carry out a drying step for removing water contained in the water-based adhesive after laminating the members. After the drying step, a curing step of curing at a temperature of 20 to 45° C., for example, may be provided.

The active energy ray-curable adhesive is an adhesive containing a curable compound that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron rays, and X-rays, and is preferably an ultraviolet ray curable adhesive. Is.

The curable compound may be a cationically polymerizable curable compound or a radically polymerizable curable compound. As the cationically polymerizable curable compound, an epoxy compound (compound having one or more epoxy groups in the molecule) and an oxetane compound (having one or more oxetane rings in the molecule) Compound), or a combination thereof. Examples of the radical-polymerizable curable compound include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule) and other radical-polymerizable double bonds. Examples thereof include vinyl compounds and combinations thereof. You may use together a cationically polymerizable curable compound and a radically polymerizable curable compound. The active energy ray-curable adhesive usually further contains a cationic polymerization initiator and/or a radical polymerization initiator for initiating a curing reaction of the curable compound.

<Front plate>
The present invention includes a circularly polarizing plate with a front plate in which a circularly polarizing plate and a front plate are laminated via an adhesive layer.
The front plate is arranged on the viewing side of the polarizing plate. The front plate can be laminated on the polarizing plate via an adhesive layer. Examples of the adhesive layer include the above-mentioned pressure-sensitive adhesive layer and adhesive layer. As shown in FIGS. 2A, 2</b>B, and 2</b>C, the front plate 4 can be laminated on the protective film 11 of the polarizing plate 1 with the pressure-sensitive adhesive layer 16 interposed therebetween.

Examples of the front plate include glass and a resin film having a hard coat layer on at least one surface thereof. As the glass, for example, high transmission glass or tempered glass can be used. Especially when a thin transparent surface material is used, chemically strengthened glass is preferable. The thickness of the glass may be, for example, 100 μm to 5 mm.

A front plate including a hard coat layer on at least one surface of a resin film can have flexible characteristics rather than being rigid like existing glass. The thickness of the hard coat layer is not particularly limited and may be, for example, 5 to 100 μm.

As the resin film, a cycloolefin derivative having a unit of a cycloolefin-containing monomer such as norbornene or a polycyclic norbornene monomer, cellulose (diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, isobutyl ester cellulose) , Propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose) ethylene-vinyl acetate copolymer, polycycloolefin, polyester, polystyrene, polyamide, polyetherimide, polyacryl, polyimide, polyamideimide, polyethersulfone, polysulfone, polyethylene, Polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate It may be a film formed of a polymer such as polyurethane, epoxy or the like. As the resin film, an unstretched, uniaxially or biaxially stretched film can be used. These polymers can be used alone or in admixture of two or more. As the resin film, a polyamide imide film or a polyimide film having excellent transparency and heat resistance, a uniaxially or biaxially stretched polyester film, a cycloolefin derivative film having excellent transparency and heat resistance and capable of responding to an increase in size of the film Polymethylmethacrylate film and triacetyl cellulose and isobutyl ester cellulose film which are transparent and optically non-anisotropic are preferred. The thickness of the resin film may be 5 to 200 μm, preferably 20 to 100 μm.

The hard coat layer can be formed by curing a hard coat composition containing a reactive material that forms a crosslinked structure by irradiation with light or heat energy. The hard coat layer can be formed by curing a hard coat composition containing a photo-curable (meth)acrylate monomer or an oligomer and a photo-curable epoxy monomer, or an oligomer at the same time. The photocurable (meth)acrylate monomer may include at least one selected from the group consisting of epoxy (meth)acrylate, urethane (meth)acrylate and polyester (meth)acrylate. The epoxy (meth)acrylate can be obtained by reacting an epoxy compound with a carboxylic acid having a (meth)acryloyl group.

The hard coat composition may further include one or more selected from the group consisting of a solvent, a photoinitiator and an additive. The additive may include one or more selected from the group consisting of inorganic nanoparticles, a leveling agent, and a stabilizer. Other than that, as each component commonly used in the art, for example, It may further include an oxidant, a UV absorber, a surfactant, a lubricant, an antifouling agent and the like.

<Shading pattern>
The light blocking pattern may be provided as at least a part of a bezel or a housing of the front plate or a display device to which the front plate is applied. The light-shielding pattern can be formed on the display element side of the front plate. The light-shielding pattern can hide each wiring of the display device so as not to be visually recognized by the user. The color and/or material of the light-shielding pattern is not particularly limited, and can be formed of resin materials having various colors such as black, white, and gold.
In one embodiment, the thickness of the light blocking pattern may be 2 μm to 50 μm, preferably 4 μm to 30 μm, and more preferably 6 μm to 15 μm. In addition, in order to prevent bubbles from entering due to a step between the light-shielding pattern and the display portion and visual recognition of the boundary portion, a shape can be given to the light-shielding pattern.

<Circular polarizing plate manufacturing method>
A method for manufacturing a circularly polarizing plate will be described by taking the circularly polarizing plate 100 shown in FIG. The circularly polarizing plate 100 can be manufactured by laminating the polarizing plate 1 and the retardation film 2 via the pressure-sensitive adhesive layer 13.

The polarizing plate 1 can be manufactured by laminating the polarizer 10 and the protective films 11 and 12 via adhesive layers. The polarizing plate may be manufactured by preparing a long member, laminating each member by roll-to-roll, and then cutting it into a predetermined shape, or cutting each member into a predetermined shape. It may be attached later. After the protective films 11 and 12 are attached to the polarizer 10, a heating step and a humidity adjusting step may be provided.

The retardation film 2 can be manufactured as follows, for example. An alignment film is formed on a substrate, and a coating liquid containing a polymerizable liquid crystal compound is applied on the alignment film. The polymerizable liquid crystal compound is cured by irradiating it with an active energy ray while the polymerizable liquid crystal compound is aligned. The pressure-sensitive adhesive layer 14 formed on the release film is laminated on the layer where the polymerizable liquid crystal compound is cured. Then, the base material and/or the alignment film is peeled off. Then, the pressure-sensitive adhesive layer 13 formed on the release film is laminated on the protective film 12. The retardation film 2 may be manufactured by preparing a long member, laminating each member by roll-to-roll, and then cutting the member into a predetermined shape. You may stick together after cutting.

Then, the release film laminated on the pressure-sensitive adhesive layer 13 is peeled off, and the retardation film 2 and the polarizing plate 1 are bonded together via the pressure-sensitive adhesive layer 13, whereby the circularly polarizing plate 100 can be manufactured. ..

<Use>
The circularly polarizing plate can be used for various display devices. A display device is a device having a display element and includes a light-emitting element or a light-emitting device as a light-emitting source. Examples of the display device include a liquid crystal display device, an organic EL display device, an inorganic electroluminescence (hereinafter, also referred to as inorganic EL) display device, an electron emission display device (for example, an electric field emission display device (FED), and a surface field emission display). Device (also referred to as SED), electronic paper (display device using electronic ink or electrophoretic element, plasma display device, projection display device (for example, grating light valve (GLV) display device), digital micromirror device (DMD) (Also referred to as a display device) and a piezoelectric ceramic display, etc. The liquid crystal display device includes any of a transmissive liquid crystal display device, a semi-transmissive liquid crystal display device, etc. These display devices have a two-dimensional image. The display device may be a display device for displaying a three-dimensional image or a stereoscopic display device for displaying a three-dimensional image The circularly polarizing plate can be particularly effectively used for an organic EL display device or an inorganic EL display device. ..

The display device of the present invention includes the circularly polarizing plate of the present invention and a display element. Examples of the display device of the present invention include those shown in FIG. 2A, 2</b>B, and 2</b>C, in the organic EL display devices 104, 105, and 106, the circularly polarizing plate displays an organic EL display via the pressure-sensitive adhesive layer 14 laminated on the retardation film 20. It has a layered structure laminated on the element 3.

[Boron content]
0.2 g of the polarizer was dissolved in 200 g of a 1.9 wt% mannitol aqueous solution. The obtained aqueous solution was titrated with a 1 mol/L sodium hydroxide aqueous solution, and the boron content of the polarizer was calculated by comparing the amount of the sodium hydroxide solution required for neutralization with the calibration curve.

[Phase difference value]
The phase difference values of the circularly polarizing plate and the phase difference film were measured using a phase difference measuring device (KOBRA-WPR manufactured by Oji Scientific Instruments Co., Ltd.).

[Hue evaluation]
When measuring the reflection hue, MIRO (5011GP) manufactured by ALANOD was used as a reflection plate. This reflection plate is a specular reflection plate having a reflection surface formed by vapor deposition.

The evaluation sample was placed on the reflection plate. The reflection hue (a*, b*) was measured using a spectrophotometer (CM-2600d manufactured by Konica Minolta Co., Ltd.). The reflection hue is a value when the light source is D65, and is measured by the SCI method (including specular reflection light).

[Visible sensitivity correction single transmittance, visibility correction polarization degree, single hue]
The luminosity-corrected single transmittance, the luminosity-corrected polarization degree, and the single hue are based on JIS Z 8701 with respect to the transmittance and the polarization degree obtained by using an absorptiometer with an integrating sphere (V7100 manufactured by JASCO Corporation). It was calculated by performing the luminosity correction with the 2-degree visual field (C light source).

[Measurement of moisture permeability]
The moisture vapor transmission rate (water vapor transmission rate) of the protective film is measured based on the method described in JIS Z 0208 under the conditions of 40° C. and 90% RH, and the value of the moisture vapor transmission rate per 1 m ² per day (24 hours). It was determined as (g/m ² ·24 hr).

[Shrinkage stress]
From the protective film of the polarizing plate, a measurement sample having a width of 2 mm and a length of 10 mm with the long side in the absorption axis direction was cut out. This sample was set in a thermomechanical analyzer (EXSTAR-6000, manufactured by SII Nano Technology Co., Ltd.), and the absorption axis direction (long-side direction) generated when the sample was held at 80°C for 4 hours with the dimensions kept constant. ) Was measured.

[Example 1]
[Production Example 1: Preparation of laminate including retardation layer 1]
A composition for forming a horizontal alignment film was prepared by mixing 5 parts (weight average molecular weight: 30,000) of a photo-alignment material having the following structure and 95 parts of cyclopentanone, and stirring the resulting mixture at 80° C. for 1 hour. I got a thing.

1.0 part of a leveling agent (F-556; manufactured by DIC Corporation) based on 100 parts of a mixture obtained by mixing the polymerizable liquid crystal compound A and the polymerizable liquid crystal compound B shown below in a mass ratio of 90:10. Then, 6 parts of 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (“Irgacure 369 (Irg369)”, manufactured by BASF Japan Ltd.), which is a polymerization initiator, was added.

Further, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration became 13%, and the mixture was stirred at 80° C. for 1 hour to obtain a retardation layer forming composition (1).

The polymerizable liquid crystal compound A was produced by the method described in JP2010-31223A.
Further, the polymerizable liquid crystal compound B was produced according to the method described in JP-A-2009-173893. The respective molecular structures are shown below.

(Polymerizable liquid crystal compound A)

(Polymerizable liquid crystal compound B)

Output of 0.3 kW using a corona treatment device (AGF-B10, manufactured by Kasuga Electric Co., Ltd.) for a base film made of a cycloolefin polymer (COP) film (ZF-14 manufactured by Nippon Zeon Co., Ltd., thickness 23 μm). Corona treatment was performed once at a treatment speed of 3 m/min. The composition for forming a horizontal alignment film was applied to the surface of the base material subjected to corona treatment by a bar coater.
The coating film was dried at 80° C. for 1 minute, and polarized UV exposure was performed using a polarized UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Inc.) with an integrated light amount of 100 mJ/cm ² . When the thickness of the obtained horizontal alignment film was measured by a laser microscope (LEXT, manufactured by Olympus Corporation), it was 100 nm.

Then, at room temperature of 25° C. and a humidity of 30% RH, the retardation layer-forming composition (1) was passed through a PTFE membrane filter (Advantech Toyo Corp., product number; T300A025A) having a pore size of 0.2 μm, It was applied using a bar coater on a substrate film with an alignment film which was kept warm at 25°C. After the coating film was dried at 120° C. for 1 minute, it was irradiated with ultraviolet rays (under nitrogen atmosphere, wavelength: 365 nm, wavelength 365 nm, integrated light quantity) using a high pressure mercury lamp (Unicure VB-15201BY-A, manufactured by Ushio Inc.). : 1000 mJ/cm ² ) to produce an optical film. When the thickness of the obtained coating film was measured with a laser microscope (LEXT, manufactured by Olympus Corporation), it was 2 μm.

In this way, a layered product in which the layer in which the polymerizable liquid crystal compound was cured (retardation layer 1), the horizontal alignment film, and the base film were laminated in this order was obtained. The retardation layer 1 was a retardation layer showing a retardation value of λ/4. The retardation layer 1 exhibited reverse wavelength dispersion.

[Production Example 2: Fabrication of laminate including retardation layer 2]
As a composition for forming a vertical alignment film, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, dipentaerythritol triacrylate, and bis(2-vinyloxyethyl) ether in a ratio of 1:1:4:5. A mixture was prepared by mixing and adding LUCIRIN TPO as a polymerization initiator at a ratio of 4%.

The retardation layer-forming composition (2) was prepared by preparing a photopolymerizable nematic liquid crystal compound (RMM28B, manufactured by Merck & Co., Inc.) and a solvent so that the solid content was 1 to 1.5 g. The solvent used was a mixed solvent in which methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone (CHN) were mixed at a mass ratio (MEK:MIBK:CHN) of 35:30:35.

A polyethylene terephthalate (PET) film having a thickness of 38 μm was prepared as a base film. The composition for forming a vertical alignment film was applied to one surface of a substrate film so as to have a film thickness of 3 μm, and ultraviolet rays of 200 mJ/cm ² were irradiated to prepare a vertical alignment film.

The retardation layer forming composition (2) was applied onto the vertical alignment layer by die coating.
The coating amount was 4 to 5 g (wet). The coating film was dried at a drying temperature of 75° C. and a drying time of 120 seconds. Then, the coating film was irradiated with ultraviolet rays (UV) to polymerize the polymerizable liquid crystal compound.

In this way, a layered product in which the layer in which the polymerizable liquid crystal compound was cured (retardation layer 2), the vertical alignment film, and the base film were laminated in this order was obtained. The retardation layer 2 was a positive C plate. The total thickness of the retardation layer 2 and the alignment film was 4 μm.

[Production Example 3: Preparation of Laminate of Retardation Layer]
The layered body including the retardation layer 1 and the layered body including the retardation layer 2 are bonded to each other by a UV-curable adhesive so that each retardation layer surface (the surface opposite to the surface on the base film side) It was pasted so that it became. Then, ultraviolet rays were irradiated to cure the ultraviolet curable adhesive. In this way, a laminate of retardation layers including the two retardation layers of retardation layer 1 and retardation layer 2 was produced.

[Production Example 4: Production of Polarizer]
A polyvinyl alcohol film having a thickness of 20 μm, a degree of polymerization of 2,400, and a degree of saponification of 99.9% or more was uniaxially stretched to a stretching ratio of 4.5 times by a dry method, and while maintaining a tension state, iodine was 0 per 100 parts by weight of water. It was immersed at 28° C. for 60 seconds in a dyeing bath containing 0.05 part by weight and 5 parts by weight of potassium iodide.

Then, it was immersed for 110 seconds at 64° C. in a boric acid aqueous solution 1 containing 5.5 parts by weight of boric acid and 15 parts by weight of potassium iodide per 100 parts by weight of water. Then, it was immersed for 30 seconds at 67° C. in a boric acid aqueous solution 2 containing 5.5 parts by weight of boric acid and 15 parts by weight of potassium iodide per 100 parts by weight of water. Then, it was washed with pure water at 3° C. and dried to obtain a polarizer.

The obtained polarizer had a luminosity-corrected single transmittance of 42.15% and a luminosity-corrected polarization degree of 99.995%. The single hue a* of the polarizer was −0.88, and the single hue b* was 3.69. The shrinkage stress of the polarizer was 99.9 N/mm ² .

[Production Example 5: Preparation of polarizing plate]
On one surface of the obtained polarizer, a saponified triacetyl cellulose (TAC) film 1 (KC2UATAC manufactured by Konica Minolta Co., Ltd., thickness: 25 μm) was pasted with a nip roll via an aqueous adhesive. On the other surface of the polarizer, a saponified triacetyl cellulose (TAC) film 2 (ZRG20SL manufactured by FUJIFILM Corporation, thickness 20 μm) was attached in the same manner as the TAC film 1. While maintaining the tension of the obtained bonded product at 430 N/m, it was dried at 60° C. for 2 minutes to obtain a polarizing plate having a TAC film on both surfaces of the polarizer. The water-based adhesive is 100 parts of water, 3 parts of carboxy group-modified polyvinyl alcohol (Kuraray Co., Ltd., Kuraray Poval KL318), and water-soluble polyamide epoxy resin (Taoka Chemical Co., Ltd., Sumirez Resin 650, solid content concentration 30%). 1.5 parts of aqueous solution) was added. The water vapor permeability of the TAC film 1 was 1200 g/m ² ·24 hr. The water vapor transmission rate of the TAC film 2 was 1500 g/m ² ·24 hr.

An acrylic pressure-sensitive adhesive layer was laminated on the TAC film 2 surface of the polarizing plate. The base film used for forming the retardation layer 1 was peeled from the layered product of the retardation layer produced in Production Example 3. The exposed horizontal alignment film and the acrylic pressure-sensitive adhesive layer were bonded together. The angle formed by the absorption axis of the polarizer and the slow axis of the retardation layer 1 was 45°. Next, the base film used for forming the retardation layer 2 was peeled off, and the acrylic pressure-sensitive adhesive layer was laminated on the exposed vertical alignment film.

In this way, a circularly polarizing plate in which the polarizing plate and the retardation film were laminated was obtained. The circularly polarizing plate includes a TAC film 1, a polarizer, a TAC film 2, an adhesive layer, a horizontal alignment film, a retardation layer 1, an adhesive layer, a retardation layer 2, a vertical alignment film, and an adhesive layer laminated in this order. It was a layered structure.

[Example 2]
A circularly polarizing plate was produced in the same manner as in Example 1 except that the TAC film 1 was attached to only one side of the polarizer when the polarizing plate was produced. The circularly polarizing plate has a layer structure in which a TAC film 1, a polarizer, an adhesive layer, a horizontal alignment film, a retardation layer 1, an adhesive layer, a retardation layer 2, a vertical alignment film, and an adhesive layer are laminated in this order. Met.

[Example 3]
A circularly polarizing plate was produced in the same manner as in Example 2 except that the boric acid content of the boric acid aqueous solution 2 was changed to 2.3 parts by weight when the polarizer was produced. The shrinkage stress of the polarizer was 88.2 N/mm ² . The transmittance of the obtained polarizer alone was 42.85%, and the degree of polarization was 90.985%. The single hue a* of the polarizer was −0.69 and the single hue b* thereof was 2.81.

[Example 4]
A circularly polarizing plate was produced in the same manner as in Example 2 except that the boric acid content of the boric acid aqueous solution 2 was changed to 1.8 parts by weight when the polarizer was produced. The shrinkage stress of the polarizer was 80.2 N/mm ² . The resulting polarizer had a luminosity-corrected single-element transmittance of 42.56% and a luminosity-corrected polarization degree of 99.993%. The single hue a* of the polarizer was −0.81 and the single hue b* was 3.17.

[Example 5]
A circularly polarizing plate was produced in the same manner as in Example 2 except that the boric acid content of the boric acid aqueous solution 2 was changed to 1.1 parts by weight when the polarizer was produced. The shrinkage stress of the polarizer was 63.2 N/mm ² . The resulting polarizer had a luminosity-corrected single transmittance of 42.30% and a luminosity-corrected polarization degree of 99.994%. The single hue a* of the polarizer was −0.90, and the single hue b* was 3.25.

[Example 6]
A polarizing plate was produced in the same manner as in Example 4.
An acrylic pressure-sensitive adhesive layer was laminated on the surface of the polarizer of the polarizing plate. In the laminate including the retardation layer 1 produced in Production Example 1, the retardation layer 1 and the acrylic pressure-sensitive adhesive layer were bonded together. The angle formed by the absorption axis of the polarizer and the slow axis of the retardation layer 1 was 45°.
After bonding, the base film used for forming the retardation layer 1 was peeled off. The exposed horizontal alignment film and the retardation layer 2 produced in Production Example 2 were attached to each other with an ultraviolet curable adhesive. Then, ultraviolet rays were irradiated to cure the ultraviolet curable adhesive. Next, the base film used for forming the retardation layer 2 was peeled off, and the acrylic pressure-sensitive adhesive layer was laminated on the exposed vertical alignment film.
In this way, a circularly polarizing plate in which the polarizing plate and the retardation film were laminated was obtained. The circularly polarizing plate has a layer structure in which a TAC film 1, a polarizer, an adhesive layer, a retardation layer 1, a horizontal alignment film, an adhesive layer, a retardation layer 2, a vertical alignment film, and an adhesive layer are laminated in this order. Met.

[Example 7]
A laminate including a retardation layer was produced in the same manner as in Production Example 1 except that the integrated light amount of ultraviolet rays irradiated when curing the polymerizable liquid crystal compound was 1500 mJ/cm ² .
A circularly polarizing plate was produced in the same manner as in Example 3 except that the retardation layer 1 was changed to the above retardation layer.

[Example 8]
A laminate including a retardation layer was produced in the same manner as in Production Example 1 except that the integrated light amount of ultraviolet rays irradiated when curing the polymerizable liquid crystal compound was 700 mJ/cm ² .
A circularly polarizing plate was produced in the same manner as in Example 3 except that the retardation layer 1 was changed to the above retardation layer.

[Comparative Example 1]
A circularly polarizing plate was produced in the same manner as in Example 2 except that the boric acid content of the boric acid aqueous solution 2 was changed to 0.7 part by weight when the polarizer was produced.
The shrinkage stress of the polarizer was 26.2 N/mm ² . The resulting polarizer had a luminosity-corrected single transmittance of 42.35% and a luminosity-corrected polarization degree of 99.994%. The single hue a* of the polarizer was −1.00 and the single hue b* was 3.35.

The circularly polarizing plates prepared in Examples and Comparative Examples were cut into a size of 150 mm×50 mm by using a super cutter and attached to a glass plate via an acrylic pressure-sensitive adhesive layer. The circularly polarizing plate laminated on glass was placed in an oven at a temperature of 85° C. and a relative humidity of 85% RH for 24 hours. Table 1 shows the amount of change in the retardation value and the amount of change in the reflection hue before and after the oven was put into the oven.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a circularly polarizing plate in which the retardation value of the retardation film is unlikely to increase even when placed in a high temperature and high humidity environment, which is useful.

DESCRIPTION OF SYMBOLS 1 Polarizing plate 2 Retardation film 3 Organic EL display element 4 Front plate 10 Polarizers 11, 12 Protective films 13, 14, 16 Adhesive layer 15 Adhesive layers 20, 21 Layers 100, 101, 103 in which a polymerizable liquid crystal compound is cured Circularly polarizing plates 104, 105, 106 Organic EL display device

Claims (10)

A circularly polarizing plate having a polarizing plate and a retardation film,
The polarizing plate includes a polarizer and a protective film attached to at least one surface of the polarizer,
The polarizer is a film in which iodine is adsorbed and oriented on a polyvinyl alcohol-based resin film,
The boron content of the polarizer is 1.00% by weight or more,
The moisture permeability of the protective film is 50 g/m ² ·24 hr or more,
The retardation film is a circularly polarizing plate including a retardation layer composed of a cured layer of a polymerizable liquid crystal compound. The circularly polarizing plate according to claim 1, wherein the thickness of the polarizer is 20 μm or less. The circularly polarizing plate according to claim 1 or 2, wherein the single-element transmittance of the polarizer is 40% or more in terms of visibility correction. The circularly polarizing plate according to any one of claims 1 to 3, wherein when the polarizer is held at 80°C for 4 hours, the contraction stress in the absorption axis direction per width of 2 mm is 60 N/mm ² or more. The single hue of the polarizer has an a* value of −0.90 or more and −0.60 or less and a b* value of 2.70 or more and 3.70 or less. Circular polarizing plate. The retardation film includes an alignment film,
The circularly polarizing plate according to claim 1, wherein the alignment film is located between the polarizer and the retardation layer. The circularly polarizing plate according to any one of claims 1 to 6, wherein the polarizing plate and the retardation film are bonded together with an active energy ray-curable adhesive. The polarizing plate includes protective films on both surfaces of the polarizer,
The moisture permeability of one protective film is 500 g/m ² ·24 hr or more,
The circularly polarizing plate according to claim 1, wherein the other protective film has a water vapor permeability of 100 g/m ² ·24 hr or less. The circularly polarizing plate according to claim 1, further comprising a front plate, a light shielding pattern, and a touch sensor. A display device comprising the circularly polarizing plate according to claim 1 and a display element.

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