JP2022191315A - Circularly polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circularly polarizing plate which comprises a retardation film including a layer of a cured liquid crystal compound, and which suppresses change in color of reflected light from an initial state after being pasted on a front plate, such as a cover glass, and exposed to a high-temperature environment.

SOLUTION: A circularly polarizing plate is provided, comprising a polarizing plate consisting of a first protection film laminated on one surface of a polarizer and a second protection film laminated on the other surface of the polarizer, and a retardation film including a layer of a cured polymerizable liquid crystal compound, the circularly polarizing film being configured to satisfy at least either of a condition 1 and a condition 2 below. Condition 1: a moisture permeability x (g/m²/24hr) of the first protection film and a moisture permeability y (g/m²/24hr) of the second protection film satisfy the following expression (1): 1/x+1/y≥0.0030 ...(1). Condition 2: the polarizing plate has a moisture content of 3.00% or less.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to a circularly polarizing plate.

2. Description of the Related Art In recent years, image display devices typified by organic electroluminescence (hereinafter also referred to as organic EL) display devices have rapidly spread. An organic EL display device is equipped with a circularly polarizing plate including a polarizer and a retardation film (λ/4 plate). By arranging the circularly polarizing plate, it is possible to prevent the reflection of external light and improve the visibility of the screen.

With the emergence of organic EL display devices, demand for thinner image display devices has increased, and thus thinner circular polarizers have also been demanded. A change from a conventional retardation film formed of a resin film to a retardation film formed using a liquid crystal compound that can be made thinner has been studied (see, for example, Patent Document 1). A retardation film using a polymerizable liquid crystal compound is produced by coating a polymerizable liquid crystal compound on a base material, aligning the compound, and fixing the alignment state by irradiating light as necessary. When a circularly polarizing plate having a retardation film formed from a polymerizable liquid crystal compound is placed in a high-temperature environment with a front plate, the color of the reflected light changes from the initial state at the center of the circularly polarizing plate. There was a problem that the light turned red.

JP 2017-54093 A

An object of the present invention is to provide a circularly polarizing plate comprising a retardation film containing a layer in which a liquid crystal compound is cured, after being placed in a high temperature environment with a front plate such as a cover glass bonded, reflected light from the initial state. To provide a circularly polarizing plate capable of suppressing a change in color of .

[1] A polarizing plate in which a first protective film is laminated on one surface of a polarizer and a second protective film is laminated on the other surface of the polarizer, and a layer in which a polymerizable liquid crystal compound is cured. comprising a retardation film and
A circularly polarizing plate that satisfies at least one of the following conditions 1 and 2.
Condition 1: When the moisture permeability of the first protective film is x (g/m ² 24 hr) and the moisture permeability of the second protective film is y (g/m ² 24 hr), the formula ( 1) is satisfied.
1/x+1/y≧0.0030 Equation (1)
Condition 2: The moisture content of the polarizing plate is 3% or less.
[2] The circularly polarizing plate of [1], which satisfies both Condition 1 and Condition 2.
[3] The circularly polarizing plate according to [1] or [2], wherein a front plate is provided on the opposite side of the polarizing plate to the side on which the retardation film is laminated.
[4] The circularly polarizing plate according to any one of [1] to [3], wherein the thickness of the polarizer is 13 μm or less.

According to the present invention, in a circularly polarizing plate comprising a retardation film including a layer in which a liquid crystal compound is cured, the reflected light from the initial state after being placed in a high-temperature environment with a front plate such as a cover glass attached. color change can be suppressed.

It is an example of the schematic sectional drawing which shows the layer structure of a circularly-polarizing plate. It is an example of the schematic sectional drawing which shows the layer structure of a circularly-polarizing plate. 1 is an example of a schematic cross-sectional view showing a layer structure of an organic EL display device; FIG.

<Circularly polarizing plate>
The circularly polarizing plate of the present invention comprises 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, which will be described later. In the present invention, the polarizing plate refers to a laminate comprising a polarizer and protective films laminated on both sides 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 FIG. 1 does not show an adhesive layer for laminating the polarizer 10 and the protective films 11 and 12, respectively. The circularly polarizing plate 100 shown in FIG. 1(a) has a first protective film 11 laminated on one side of the polarizer 10 and a second protective film 12 laminated on the other side of the polarizer 10. It has a layer structure in which a polarizing plate 1 and a retardation film 2 including a layer 20 in which a polymerizable liquid crystal compound is cured 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 adhesive layer 14 can be an adhesive layer for bonding to an organic EL display element or the like.

Circularly polarizing plate 101 shown in FIG. 1B has first protective film 11 laminated on one side of polarizer 10 and second protective film 12 laminated on the other side of polarizer 10. It has a layer structure in which a polarizing plate 1 and a retardation film 2 are laminated with an adhesive layer 13 interposed therebetween. In the circularly polarizing plate 101 , the retardation film 2 has a layer structure in which a layer 20 obtained by curing a polymerizable liquid crystal compound and a layer 21 obtained by curing a polymerizable liquid crystal compound 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 adhesive layer 14 can be an adhesive layer for bonding to an organic EL display element or the like.

As shown in FIG. 1, the retardation film may have one layer or two layers in which the polymerizable liquid crystal compound is cured. Further, the retardation film may have an alignment film for orienting the polymerizable liquid crystal compound and a substrate film.

The circular polarizer can have layers other than those shown in FIG. Layers that the circularly polarizing plate may further include include a front plate and a light shielding pattern. The front plate can be arranged on the opposite side of the polarizing plate to the side on which the retardation film is laminated. The circularly polarizing plate 102 shown in FIG. 2( a ) is obtained by laminating the front plate 4 on the circularly polarizing plate 100 , and the front plate 4 is laminated on the polarizing plate 1 via the adhesive layer 16 . The circularly polarizing plate 103 shown in FIG. 2B is obtained by laminating the front plate 4 on the circularly polarizing plate 101 , and the front plate 4 is laminated on the polarizing plate 1 via the adhesive layer 16 .

The light shielding pattern can be formed on the polarizing plate side surface of the front plate. The light shielding pattern is formed in the frame (non-display area) of the image display device, and can prevent the wiring of the image display device from being visually recognized by the user.

The circularly polarizing plate of the present invention satisfies at least one of Condition 1 and Condition 2 below.
Condition 1: When the moisture permeability of the first protective film is x (g/m ² 24 hr) and the moisture permeability of the second protective film is y (g/m ² 24 hr), the formula ( 1) is satisfied.
1/x+1/y≧0.0030 Equation (1)
Condition 2: The moisture content of the polarizing plate is 3.00% or less.

When the circularly polarizing plate satisfies at least one of the conditions 1 and 2 above, the color of the central portion of the circularly polarizing plate is prevented from changing when the circularly polarizing plate is placed in a high-temperature environment. be able to. The circularly polarizing plate preferably satisfies both conditions 1 and 2 above.

More specifically, in formula (1), 1/x+1/y is 0.0030 or more, preferably 0.010 or more, more preferably 0.020 or more, and 0.050 or more. is more preferable. Although the upper limit is not particularly limited, 1/x+1/y is usually 0.2 or less.

More specifically, the moisture content of the polarizing plate is 3.00% or less, preferably 2.50% or less, and more preferably 2.00% or less. Although the lower limit is not particularly limited, the moisture content of the polarizing plate is usually 0.50% or more, and may be 1.00% or more. The method for measuring the moisture content follows the method described in Examples below.

Although not intended to limit the present invention in any way, the reason why it is possible to prevent the reflected light from turning red by satisfying the conditions 1 and 2 is presumed as follows. As a result of investigations by the present inventors, it has become clear that the phenomenon in which the reflected light from the central portion of the circularly polarizing plate turns red is caused by a decrease in the retardation value of the retardation film. It was presumed that the decrease in the retardation value of the retardation film was caused by the migration of moisture contained in the polarizing plate to the retardation film. Therefore, the moisture content contained in the polarizing plate is set to a predetermined value or less to reduce the amount of moisture that can migrate to the retardation film, or the moisture permeability of the protective film included in the polarizing plate is set to a predetermined value or less to obtain the retardation film. It is effective to make it difficult for moisture to migrate to.

Condition 2 is based on the above estimation, and by setting the moisture content of the polarizing plate within the above range, it is possible to prevent the reflected light from the circularly polarizing plate from turning red. On the other hand, condition 1, surprisingly, not only the moisture permeability of the protective film on the side closer to the retardation film in the polarizing plate, but also the moisture permeability of the protective film on the side farther from the retardation film in the polarizing plate This is based on the fact that it has been clarified that it is important for preventing the discoloration of the reflected light. According to the study of the present inventors, by selecting the moisture permeability of the protective films laminated on both sides of the polarizing plate so as to satisfy the above condition 1, the reflected light from the circularly polarizing plate is prevented from turning red. be able to.

When the circularly polarizing plate of the present invention is heated at 85° C. for 400 hours, the magnitude of the decrease in retardation value ΔRe (nm) at the in-plane center (which may be the position of the center of gravity of the circularly polarizing plate) is It is preferably 10 nm or less, more preferably 8 nm or less. A value at a wavelength of 547 nm is adopted as the phase difference value. By setting it as such a range, the color change of a circularly-polarizing plate can be made small, and a circularly-polarizing plate with a favorable external appearance is obtained.

The shape of the circularly polarizing plate of the present invention is not particularly limited. When the circularly polarizing plate is substantially rectangular, the length of the long side is preferably 5 cm or more and 35 cm or less, more preferably 10 cm or more and 25 cm or less, and the length of the short side is 5 cm or more and 25 cm or less. It is preferably 6 cm or more and 20 cm or less. With such a size, it is difficult for moisture to be trapped.

The term “substantially rectangular” means that the circularly polarizing plate has a shape in which at least one of the four corners (corners) of the main surface is cut off so that at least one corner has an obtuse angle or a rounded shape. or a part of the end face perpendicular to the main surface has a recess (notch) recessed in the in-plane direction, or a part of the main surface is circular, elliptical, polygonal, or a combination thereof. It means that it may have a perforated part hollowed out in the shape of

<Polarizing plate>
In the present invention, the polarizing plate refers to a laminate comprising a polarizer and protective films laminated on both sides of the polarizer. The protective film included in the polarizing plate may have a surface treatment layer such as a hard coat layer, an antireflection layer, an antistatic layer, and the like, which will be described later. A polarizer and a protective film can be laminated via an adhesive layer or a pressure-sensitive adhesive layer, for example. Members included in the polarizing plate will be described below.

(1) Polarizer A polarizer provided 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 absorptive polarizer having properties. As the polarizer included in the first layer, a polarizer in which a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol resin film can be suitably used. The polarizer is, for example, a process of uniaxially stretching a polyvinyl alcohol resin film; a process of dyeing a polyvinyl alcohol resin film with a dichroic dye to adsorb a dichroic dye; It can be produced by a method including a step of treating an alcohol-based resin film with a cross-linking liquid such as an aqueous boric acid solution; and a step of washing with water after the treatment with the cross-linking liquid.

As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. Examples of polyvinyl acetate-based resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate with other monomers that can be copolymerized. 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.

As used herein, "(meth)acryl" means at least one selected from acryl and methacryl. The same applies to "(meth)acryloyl", "(meth)acrylate" and the like.

The saponification degree of the polyvinyl alcohol 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 resin is usually 1,000 to 10,000, preferably 1,500 to 5,000. The average degree of polymerization of the polyvinyl alcohol-based resin can be determined according to JIS K6726.

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

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing with the dichroic dye, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before or during the cross-linking treatment. Moreover, you may uniaxially stretch in these several steps.

In the uniaxial stretching, the film may be uniaxially stretched between rolls having different circumferential speeds, or may be uniaxially stretched using hot rolls. The uniaxial stretching may be dry stretching in which the film is stretched in the atmosphere, or wet stretching in which the polyvinyl alcohol resin film is stretched in a swollen state using 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 a dichroic dye, for example, a method of immersing the film in an aqueous solution containing a dichroic dye is employed. Iodine and dichroic organic dyes are used as dichroic dyes. The polyvinyl alcohol resin film is preferably immersed in water before being dyed.

As a cross-linking treatment after dyeing with a dichroic dye, a method of immersing a dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid is usually adopted. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide.

The thickness of the polarizer is usually 30 µm or less, preferably 15 µm or less, more preferably 13 µm or less, still more preferably 10 µm or less, and particularly preferably 8 µm or less. In particular, setting the thickness of the polarizer to 15 μm or less is advantageous for reducing the water content of the polarizing plate per unit area. The thickness of the polarizer is usually 2 μm or more, preferably 3 μm or more.

As the polarizer, for example, as described in JP-A-2016-170368, a cured film in which a liquid crystal compound is polymerized and a dichroic dye oriented may be used. As the dichroic dye, those having absorption in the wavelength range of 380 to 800 nm can be used, and organic dyes are preferably used. Dichroic dyes include, for example, azo compounds.
A liquid crystal compound is a liquid crystal compound that can be polymerized while being aligned, and can have a polymerizable group in its molecule. Also, as described in WO2011/024891, a polarizer may be formed from a dichroic dye having liquid crystallinity.

(2) Protective film Based on the polarizer, the moisture permeability of the protective film (first protective film) on the far side from the retardation film is preferably 500 g/m ² · 24 hr or less, and 200 g / m ² · It is more preferably 24 hr or less, further preferably 100 g/m ² ·24 hr or less, and may be 50 g/m ² ·24 hr or less. Although the lower limit is not particularly limited, it is usually over 0 g/m ² ·24 hr.

Based on the polarizer, the moisture permeability of the protective film (second protective film) on the side closer to the retardation film is preferably 500 g/m ² 24 hr or less, and 200 g/m ² 24 hr or less. is more preferably 100 g/m ² ·24 hr or less, and may be 50 g/m ² ·24 hr or less. Although the lower limit is not particularly limited, it is usually over 0 g/m ² ·24 hr.

The first protective film and the second protective film may have the same moisture permeability, or may have different moisture permeability. The moisture permeability can be measured under conditions of a temperature of 40° C. and a relative humidity of 90% according to the moisture permeability test (cup method) of JIS Z0208.

The protective films laminated on both sides of the polarizer are made of translucent (preferably optically transparent) thermoplastic resins such as linear polyolefin resins (polypropylene resins, etc.), cyclic polyolefin resins (norbornene polyolefin resins such as polyolefin resins); cellulose resins such as triacetyl cellulose and diacetyl cellulose; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate resins; meth) acrylic resin; polystyrene resin; polyvinyl chloride resin; acrylonitrile-butadiene-styrene resin; acrylonitrile-styrene resin; polyvinyl acetate resin; It can be a film made of a modified polyphenylene ether-based resin; a polysulfone-based resin; a polyethersulfone-based resin; a polyarylate-based resin; a polyamideimide-based resin;

Examples of linear polyolefin resins include polyethylene resins (polyethylene resins that are homopolymers of ethylene and copolymers that are mainly composed of ethylene), polypropylene resins (polypropylene resins that are homopolymers of propylene, and propylene resins that are mainly composed of propylene). In addition to homopolymers of chain olefins such as copolymers that form a chain olefin, copolymers composed of two or more types of chain olefins can be mentioned.

Cyclic polyolefin-based resin is a general term for resins polymerized using cyclic olefins as polymerized units, and is described, for example, in JP-A-1-240517, JP-A-3-14882, and JP-A-3-122137. resins. Specific examples of cyclic polyolefin-based resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and chain olefins such as ethylene and propylene (typically are random copolymers), graft polymers modified with unsaturated carboxylic acids or derivatives thereof, and hydrides thereof. Among them, norbornene-based resins using norbornene-based monomers such as norbornene and polycyclic norbornene-based monomers as cyclic olefins are preferably used.

Polyester-based resins are resins having an ester bond, except for the cellulose ester-based resins described below, and generally consist of polycondensates of polyhydric carboxylic acids or derivatives thereof and polyhydric alcohols. Divalent dicarboxylic acids or derivatives thereof can be used as polyvalent carboxylic acids or derivatives thereof, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. Dihydric diols can be used as polyhydric alcohols, such as ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. A representative example of the polyester resin is polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol.

A (meth)acrylic resin is a resin containing a compound having a (meth)acryloyl group as a main constituent monomer. Specific examples of (meth)acrylic resins include, for example, poly(meth)acrylic acid esters such as polymethyl methacrylate; methyl methacrylate-(meth)acrylic acid copolymer; methyl methacrylate-(meth)acrylic acid Ester copolymer; methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymer; methyl (meth)acrylate-styrene copolymer (MS resin, etc.); (eg, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth)acrylate copolymer, etc.). Preferably, a polymer containing poly (meth)acrylic acid C _1-6 alkyl ester as a main component such as polymethyl (meth)acrylate is used, and more preferably a polymer containing methyl methacrylate as a main component (50 to 100 % by weight, preferably 70 to 100% by weight) is used.

Cellulose ester resin is an ester of cellulose and fatty acid. Specific examples of cellulose ester resins include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Copolymers thereof and those in which a part of hydroxyl groups are modified with other substituents are also included. Among these, cellulose triacetate (triacetylcellulose) is particularly preferred.

Polycarbonate-based resins are engineering plastics composed of polymers in which monomer units are linked via carbonate groups.

It is also useful to control the retardation value of the protective film to a value suitable for an image display device such as a liquid crystal display device. For example, in an in-plane switching (IPS) mode liquid crystal display device, it is preferable to use a film having substantially zero retardation value as the protective film. A substantially zero retardation value means that the in-plane retardation value Re(550) at a wavelength of 550 nm is 10 nm or less, and the absolute value of the thickness direction retardation value Rth at a wavelength of 550 nm is 10 nm or less. The absolute value of the thickness direction retardation value Rth at a wavelength of 480 to 750 nm is preferably 15 nm or less. Further, in order to improve the visibility of the screen when the user wears polarized sunglasses or the like, the in-plane retardation value Re(550) at a wavelength of 550 nm may be 70 to 140 nm.

For example, depending on the mode of the liquid crystal display device, the protective film may be stretched and/or shrunk to impart a suitable retardation. For example, for the purpose of viewing angle compensation, a single-layer or multi-layer retardation layer (or film) can be used as the protective film.

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

The protective films attached to both surfaces of the polarizer may be composed of the same type of thermoplastic resin, or may be composed of different types of thermoplastic resins. Moreover, the thickness may be the same or may be different. Furthermore, they may have the same phase difference characteristics or different phase difference characteristics.

As described above, at least one of the protective films has, on its outer surface (the surface opposite to the polarizer), a hard coat layer, an antiglare layer, a light diffusion layer, an antireflection layer, a low refractive index layer, a charging A surface treatment layer (coating layer) such as an antifouling layer and an antifouling layer may be provided. The thickness of the protective film includes the thickness of the surface treatment layer.

The protective film can be attached to the polarizer via an adhesive layer or a pressure-sensitive adhesive layer, for example. As the adhesive for forming the adhesive layer, a water-based adhesive, an active energy ray-curable adhesive or a thermosetting adhesive can be used, preferably a water-based adhesive or an active energy ray-curable adhesive. As the adhesive layer, those described later can be used.

Examples of water-based adhesives include adhesives composed of a polyvinyl alcohol-based resin aqueous solution, water-based two-liquid type urethane-based emulsion adhesives, and the like. Among them, a water-based adhesive composed of an aqueous polyvinyl alcohol resin solution is preferably used. Polyvinyl alcohol-based resins include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate with other monomers copolymerizable therewith. A polyvinyl alcohol-based copolymer obtained by saponifying a polymer, or a modified polyvinyl alcohol-based polymer obtained by partially modifying the hydroxyl groups thereof can be used. The water-based adhesive can contain cross-linking agents such as aldehyde compounds (glyoxal, etc.), epoxy compounds, melamine compounds, methylol compounds, isocyanate compounds, amine compounds, polyvalent metal salts, and the like.

When using a water-based adhesive, it is preferable to carry out a drying process for removing water contained in the water-based adhesive after bonding the polarizer and the protective film. After the drying step, a curing step of curing at a temperature of, for example, 20 to 45°C may be provided.

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

The curable compound can be a cationically polymerizable curable compound or a radically polymerizable curable compound. Examples of cationic polymerizable curable compounds include epoxy compounds (compounds having one or more epoxy groups in the molecule) and oxetane compounds (one or two or more oxetane rings in the molecule). compound), or a combination thereof. Examples of radically polymerizable curable compounds include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule) and radically polymerizable double bonds. Other vinyl-based compounds or combinations thereof can be included. A cationic polymerizable curable compound and a radically polymerizable curable compound may be used in combination. The active energy ray-curable adhesive usually further contains a cationic polymerization initiator and/or a radical polymerization initiator for initiating the curing reaction of the curable compound.

When bonding the polarizer and the protective film, surface activation treatment may be applied to the bonding surface of at least one of them in order to enhance the adhesiveness. Surface activation treatments include dry treatments such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, ionizing active ray treatment (ultraviolet treatment, electron beam treatment, etc.). ; ultrasonic treatment using a solvent such as water or acetone, saponification treatment, and wet treatment such as anchor coating treatment can be mentioned. These surface activation treatments may be performed singly or in combination of two or more.

When the protective films are laminated on both sides of the polarizer, the adhesive for laminating these protective films may be of the same type or different types.

<Retardation film>
A retardation film has a layer composed of a composition containing a polymerizable liquid crystal compound. A layer composed of a composition containing a polymerizable liquid crystal compound specifically means a layer in which the polymerizable liquid crystal compound is cured. In the present specification, a layer giving a retardation of λ/2, a layer giving a retardation of λ/4 (positive A layer), a positive C layer, etc. may be collectively referred to as a retardation layer.
Furthermore, the retardation film may contain a substrate and an alignment film, which will be described later.

A layer in which a polymerizable liquid crystal compound is cured is formed, for example, on an alignment film provided on a substrate. The base material may be a base material having a function of supporting the alignment film and formed in an elongated shape. This substrate functions as a release support and can support a retardation layer for transfer. Furthermore, it is preferable that the surface has adhesive strength to the extent 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, for example, 20 μm or more and 200 μm or less. Strength is imparted when the thickness of the substrate is 20 μm or more. On the other hand, if the thickness is 200 μm or less, it is possible to suppress an increase in processing waste and wear of the cutting blade when cutting the base material into a sheet base material.

The substrate may be subjected to various antiblocking treatments. Anti-blocking treatments include, for example, easy-adhesion treatments, kneading treatments with fillers and the like, embossing (knurling treatments), and the like. By applying such antiblocking treatment to the base material, it is possible to effectively prevent sticking between the base materials when winding the base material, that is, so-called blocking, and to produce an optical film with high productivity. becomes possible.

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

The alignment film is not limited to a vertical alignment film, and may be an alignment film that horizontally aligns the molecular axis of the polymerizable liquid crystal compound, or an alignment film that tilts the molecular axis of the polymerizable liquid crystal compound. . The alignment film has a solvent resistance that does not dissolve when a composition containing a polymerizable liquid crystal compound described later is applied, etc., and also has heat resistance in heat treatment for solvent removal and alignment of the liquid crystal compound. preferable. Examples of the alignment film include an alignment film containing an alignment polymer, a photo-alignment film, and a groove alignment film in which an uneven pattern or a plurality of grooves are formed on the surface for alignment. The thickness of the alignment film is usually in the range of 10 nm to 10000 nm, preferably 10 nm to 1000 nm, more preferably 500 nm or less, and still more preferably 10 nm to 200 nm.

The resin used for the alignment film is not particularly limited as long as it is a resin used as a material for a known alignment film. A cured product or the like can be used. Specifically, (meth)acrylate monomers include, for example, 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono-2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, trimethylolpropane triacrylate. , lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate , cyclohexyl methacrylate, methacrylic acid, urethane acrylate, and the like. In addition, as resin, these 1 types may be sufficient, and the mixture of 2 or more types may be sufficient.

Although the type of the polymerizable liquid crystal compound used in the present embodiment is not particularly limited, it is classified into a rod-shaped type (rod-shaped liquid crystal compound) and a disk-shaped type (disk-shaped liquid crystal compound, discotic liquid crystal compound) according to its shape. can. Furthermore, there are low-molecular-weight types and high-molecular-weight types, respectively. Polymers generally refer to those having a degree of polymerization of 100 or more (polymer physics, phase transition dynamics, Masao Doi, p. 2, Iwanami Shoten, 1992).

Any polymerizable liquid crystal compound can be used in the present embodiment. Furthermore, two or more kinds of rod-like liquid crystal compounds, two or more kinds of discotic liquid crystal compounds, or mixtures of rod-like liquid crystal compounds and discotic liquid crystal compounds may be used.

As the rod-like liquid crystal compound, for example, claim 1 of JP-A-11-513019, or paragraphs [0026] to [0098] of JP-A-2005-289980 can be preferably used. can be done. As the discotic liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP-A-2007-108732, or paragraphs [0013] to [0108] of JP-A-2010-244038 are suitable. can be used for

Two or more types of polymerizable liquid crystal compounds may be used in combination. In that case, at least one type 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 a 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.

A 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 an addition polymerization reaction such as a polymerizable ethylenically unsaturated group or a ring-polymerizable group is preferable. More specifically, examples of polymerizable groups include (meth)acryloyl groups, vinyl groups, styryl groups, and allyl groups. Among them, a (meth)acryloyl group is preferred. In addition, a (meth)acryloyl group is a concept including both a methacryloyl group and an acryloyl group.

A layer in which a polymerizable liquid crystal compound is cured can be formed by coating a composition containing a polymerizable liquid crystal compound, for example, on an alignment film, as described later. The composition may contain components other than the polymerizable liquid crystal compound described above. For example, 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 photopolymerization initiators include α-carbonyl compounds, acyloin ethers, α-hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, combinations of triarylimidazole dimers and p-aminophenyl ketones, and the like. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the total solid content in the coating liquid.

Moreover, the composition may contain a polymerizable monomer from the viewpoint of the uniformity of the coating film and the strength of the film. Polymerizable monomers include radically polymerizable or cationically polymerizable compounds. Among these, polyfunctional radically polymerizable monomers are preferred.

As the polymerizable monomer, one that can be copolymerized with the polymerizable liquid crystal compound described above is preferable. Specific polymerizable monomers include, for example, those described in paragraphs [0018] to [0020] of JP-A-2002-296423. The amount of the polymerizable monomer used is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, based on the total mass of the polymerizable liquid crystal compound.

Further, the composition may contain a surfactant from the viewpoint of the uniformity of the coating film and the strength of the film. Surfactants include conventionally known compounds. Among them, fluorine-based compounds are particularly preferable. Specific surfactants include, for example, compounds described in paragraphs [0028] to [0056] in JP-A-2001-330725, paragraphs [0069] to [0126 in Japanese Patent Application No. 2003-295212. ] and the compound described in .

Moreover, the composition may contain a solvent, and an organic solvent is preferably used.
Examples of organic solvents 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). Among them, alkyl halides and ketones are preferred. Moreover, you may use together 2 or more types of organic solvents.

Further, the composition contains a vertical alignment accelerator such as a polarizer interface side vertical alignment agent and an air interface side vertical alignment agent, and a horizontal alignment accelerator such as a polarizer interface side horizontal alignment agent and an air interface side horizontal alignment agent. Various alignment agents may also be included. Furthermore, the composition may contain an adhesion improver, a plasticizer, a polymer, etc., in addition to the above components.

In this embodiment, the thickness of the retardation layer is preferably 0.5 μm or more. Moreover, the thickness of the retardation layer is preferably 10 μm or less, more preferably 5 μm or less. In addition, the upper limit value and the lower limit value mentioned above can be combined arbitrarily. Sufficient durability is acquired as the thickness of a retardation layer is more than the said lower limit. When the thickness of the retardation layer is equal to or less than the upper limit, it can contribute to making the circularly polarizing plate thinner. The thickness of the retardation layer is a layer that provides a retardation of λ/4, a layer that provides a retardation of λ/2, or a desired in-plane retardation value of the positive C layer and a retardation value in the thickness direction. can be adjusted accordingly.

The retardation film may include one layer in which the polymerizable liquid crystal compound is cured, or may include two or more layers in which the polymerizable liquid crystal compound is cured. When the retardation film includes two layers in which the polymerizable liquid crystal compound is cured, the two layers are a layer giving a retardation of λ / 4 and a positive C layer, or a layer giving a retardation of λ / 4 and λ / 2 is preferably a layer that provides a retardation of When the retardation film includes two layers in which the polymerizable liquid crystal compound is cured, each layer in which the polymerizable liquid crystal compound is cured is formed on the alignment film, and both are laminated via an adhesive layer or a pressure-sensitive adhesive layer. Thereby, a retardation film can be produced. After laminating both, the substrate and the alignment film can be peeled off. The thickness of the retardation film is preferably 3 to 30 μm, more preferably 5 to 25 μm.

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

Examples of the (meth)acrylic resin (base polymer) used in the adhesive composition include butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-(meth)acrylate. Polymers or copolymers containing one or more of (meth)acrylic acid esters such as ethylhexyl as monomers are preferably used. Preferably, the base polymer is copolymerized with a polar monomer. Examples of polar monomers include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, glycidyl ( Monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, etc., such as meth)acrylates, can be mentioned.

The pressure-sensitive adhesive composition may contain only the above base polymer, but usually further contains a cross-linking agent. The cross-linking agent is a metal ion having a valence of 2 or more, which forms a carboxylic acid metal salt with a carboxyl group; a polyamine compound, which forms an amide bond with a carboxyl group; Examples include epoxy compounds and polyols that form ester bonds with carboxyl groups; and polyisocyanate compounds that form amide bonds with carboxyl groups. Among them, polyisocyanate compounds are preferred.

<Front plate>
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 adhesive layer and the adhesive layer described above. As shown in FIGS. 2A and 2B, the front plate 4 can be laminated on the first protective film 11 of the polarizing plate 1 with an adhesive layer 16 interposed therebetween.

When the front plate is laminated on the circularly polarizing plate, the reflected light from the circularly polarizing plate tends to turn red. This is probably because the front plate often has a low moisture permeability, and moisture contained in the polarizing plate tends to be trapped. Therefore, the circularly polarizing plate of the present invention exhibits remarkable effects when provided with a front plate.

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 using a thin transparent surface material, chemically strengthened glass is preferable. The thickness of the glass can be, for example, 100 μm to 5 mm.

A front panel comprising a hard coat layer on at least one surface of a resin film can have flexible characteristics, unlike existing glass, which is not rigid. The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 to 100 μm.

Examples of resin films include cycloolefin-based derivatives having units of monomers containing cycloolefins such as norbornene or polycyclic norbornene-based monomers, cellulose (diacetylcellulose, triacetylcellulose, acetylcellulose butyrate, isobutyl ester cellulose, , propionyl cellulose, butyryl cellulose, acetylpropionyl 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, polyetherketone, polyetheretherketone, polyethersulfone, polymethylmethacrylate, polyethyleneterephthalate, polybutyleneterephthalate, polyethylenenaphthalate, polycarbonate , polyurethane, and epoxy. Unstretched, uniaxially stretched or biaxially stretched film can be used as the resin film. These polymers can be used alone or in combination of two or more. Resin films include polyamide-imide films or polyimide films with excellent transparency and heat resistance, uniaxially or biaxially oriented polyester films, and cycloolefin derivative films with excellent transparency and heat resistance that can be used for larger films. , polymethyl methacrylate films and transparent and optically non-anisotropic triacetyl cellulose and isobutyl ester cellulose films are preferred. The thickness of the resin film may be 5-200 μm, preferably 20-100 μm.

The hard coat layer can be formed by curing a hard coat composition containing a reactive material that forms a crosslinked structure upon exposure to light or heat energy. The hard coat layer can be formed by curing a hard coat composition containing a photocurable (meth)acrylate monomer or oligomer and a photocurable epoxy monomer or oligomer at the same time. The photocurable (meth)acrylate monomer may include one or more 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 (meth)acryloyl group-containing carboxylic acid.

The hardcoat composition may further include one or more selected from the group consisting of solvents, photoinitiators and additives. The additive can include one or more selected from the group consisting of inorganic nanoparticles, leveling agents and stabilizers, and other components commonly used in the art, such as Oxidizing agents, UV absorbers, surfactants, lubricants, antifouling agents and the like can be further included.

<Light shielding pattern>
The light shielding pattern can be provided as at least part of the front panel or the bezel or housing of the display device to which the front panel 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 that it cannot be visually recognized by the user. The color and/or material of the light-shielding pattern is not particularly limited, and may be formed of resin materials having various colors such as black, white, and gold.
In one embodiment, the thickness of the light shielding pattern may range from 2 μm to 50 μm, preferably from 4 μm to 30 μm, more preferably from 6 μm to 15 μm. Further, in order to suppress the inclusion of bubbles due to the difference in level between the light shielding pattern and the display portion and the visibility of the boundary portion, the light shielding pattern can be given a shape. For example, the light-shielding pattern may have an inclination angle of 0.1° to 25° with respect to the front panel on which the light-shielding pattern is formed on the surface adjacent to the display section.

<Method for manufacturing circularly polarizing plate>
A method for manufacturing a circularly polarizing plate will be described using the circularly polarizing plate 100 shown in FIG. 1(a) as an example. The circularly polarizing plate 100 can be produced by laminating the polarizing plate 1 and the retardation film 2 with the adhesive layer 13 interposed therebetween.

The polarizing plate 1 can be manufactured by laminating a polarizer 10 and protective films 11 and 12 with adhesive layers interposed therebetween. The polarizing plate may be produced by preparing long members, bonding the respective members together by roll-to-roll, and then cutting them into a predetermined shape, or by cutting each member into a predetermined shape. Afterwards, they can be pasted together. After attaching the protective films 11 and 12 to the polarizer 10, a heating process or a humidity control process may be provided in order to adjust the moisture content of the polarizing plate. Next, the adhesive layer 13 formed on the release film is laminated on the protective film 12 .

The retardation film 2 can be manufactured, for example, as follows. An alignment film is formed on a substrate, and a coating liquid containing a polymerizable liquid crystal compound is applied onto the alignment film. While the polymerizable liquid crystal compound is oriented, it is irradiated with an active energy ray to cure the polymerizable liquid crystal compound. The pressure-sensitive adhesive layer 14 formed on the release film is laminated on the layer in which the polymerizable liquid crystal compound is cured. Then, the substrate and/or the alignment film are peeled off. The retardation film 2 may be manufactured by preparing long members, bonding the respective members together by roll-to-roll, and then cutting them into a predetermined shape, or by cutting each member into a predetermined shape. After cutting, it may be pasted together.

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

<Application>
Circularly polarizing plates can be used in 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 source. Examples of display devices include liquid crystal display devices, organic EL display devices, inorganic electroluminescence (hereinafter also referred to as inorganic EL) display devices, electron emission display devices (for example, field emission display devices (also referred to as FED), and surface field emission displays). device (also called 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 and piezoelectric ceramic displays, etc. Liquid crystal display devices include both transmissive liquid crystal display devices, transflective liquid crystal display devices, etc. These display devices can display two-dimensional images. It may be a display device that displays or a stereoscopic display device that displays a three-dimensional image.The circularly polarizing plate can be particularly effectively used in an organic EL display device or an inorganic EL display device. .

In FIGS. 3A and 3B, the organic EL display devices 104 and 105 have a circularly polarizing plate laminated on the organic EL display element 3 via an adhesive layer 14 laminated on the retardation film 20. It has a layered structure.

(1) Method for measuring film thickness Measured using MH-15M, a digital micrometer manufactured by Nikon Corporation.

(2) Method for Measuring Moisture Permeability The moisture permeability of the protective film was measured according to the moisture permeability test (cup method) of JIS Z0208. The measurement conditions were a temperature of 40° C. and a relative humidity of 90%.

(3) Method for measuring phase difference value Measured using a phase difference measuring device KOBRA-PR (manufactured by Oji Scientific Instruments Co., Ltd.).

(4) Method for measuring moisture content of polarizing plate The moisture content of the polarizing plate was calculated by the dry weight method. The weight W1 of the polarizing plate after drying at 105° C. for 2 hours and the weight W0 of the polarizing plate before drying were measured. These values were substituted into the following formula to calculate the moisture content of the polarizing plate.
Moisture content of polarizing plate [%] = {(W0-W1) ÷ W0} × 100

<Preparation of Polarizer A>
Polyvinyl alcohol film with a thickness of 20 μm (average degree of polymerization: about 2400, degree of saponification: 99.9 mol% or more) is uniaxially stretched by dry stretching to about 4 times, and furthermore, while maintaining tension, it is placed in pure water at 40 ° C. After being immersed for 40 seconds, it was dyed by being immersed in an aqueous solution of iodine/potassium iodide/water at a weight ratio of 0.052/5.7/100 at 28° C. for 30 seconds. After that, it was immersed in an aqueous solution of potassium iodide/boric acid/water at a weight ratio of 11.0/6.2/100 at 70° C. for 120 seconds. Subsequently, after washing with pure water at 8°C for 15 seconds, the film was dried at 60°C for 50 seconds and then at 75°C for 20 seconds while maintaining a tension of 300N. A polarizing film having a thickness of 8 μm was obtained.

<Production of polarizer B>
In the same manner as in the production of the polarizer (A), except that a polyvinyl alcohol film with a thickness of 30 μm (average degree of polymerization: about 2400, degree of saponification: 99.9 mol% or more) was used instead of the polyvinyl alcohol film with a thickness of 20 μm. A polarizer (B) having a thickness of 13 μm in which iodine was adsorbed and oriented on a polyvinyl alcohol film was obtained.

<Production of polarizer C>
In the same manner as in the production of the polarizer (A), except that a polyvinyl alcohol film with a thickness of 60 μm (average degree of polymerization: about 2400, degree of saponification: 99.9 mol% or more) was used instead of the polyvinyl alcohol film with a thickness of 20 μm. A polarizer (C) having a thickness of 23 μm in which iodine was adsorbed and oriented on a polyvinyl alcohol film was obtained.

<Production of polarizer D>
In the same manner as in the preparation of the polarizer (A), except that a polyvinyl alcohol film with a thickness of 75 μm (average degree of polymerization: about 2400, degree of saponification: 99.9 mol% or more) was used instead of the polyvinyl alcohol film with a thickness of 20 μm. A polarizer (D) having a thickness of 28 μm in which iodine was adsorbed and oriented on a polyvinyl alcohol film was obtained.

<Preparation of water-based adhesive>
3 parts by weight of carboxyl group-modified polyvinyl alcohol (trade name "KL-318" obtained from Kuraray Co., Ltd.) is dissolved in 100 parts by weight of water, and a polyamide epoxy additive (Taoka), which is a water-soluble epoxy resin, is dissolved in the aqueous solution. A water-based adhesive was prepared by adding 1.5 parts by weight of "Sumireze Resin (registered trademark) 650 (30)", an aqueous solution with a solid concentration of 30% by weight, available from Kagaku Kogyo Co., Ltd.).

<Preparation of adhesive layer>
Adhesive Layer A: An acrylic adhesive layer having a thickness of 25 μm was prepared on a release film.
Adhesive Layer B: An acrylic adhesive layer having a thickness of 5 μm was prepared on a release film.
Adhesive Layer C: An acrylic adhesive layer having a thickness of 20 μm was prepared on a release film.

<Preparing the protective film>
The following protective films were prepared.
Protective film A: A norbornene-based resin film having a thickness of 20 µm.
Protective film B: A norbornene-based resin film having a hard coat layer formed on one surface. Protective film B had a thickness of 52 µm.
Protective film C: A TAC film having a hard coat layer formed on one surface. Protective film C had a thickness of 31 µm.
Protective film D: A norbornene-based resin film having a hard coat layer formed on one surface. Protective film C had a thickness of 29 µm.
Protective film E: TAC film with a thickness of 40 μm.
Protective film F: A norbornene-based resin film having a thickness of 13 μm.
Protective film G: TAC film with a thickness of 25 μm.
Protective film H: TAC film with a thickness of 20 μm.

<Preparation of retardation film>
5 parts of a photo-alignable material having the following structure (weight average molecular weight: 30000) and 95 parts of cyclopentanone (solvent) are mixed as components, and the resulting mixture is stirred at 80° C. for 1 hour to form an alignment film. A composition for

1.0 parts of a leveling agent (F-556; manufactured by DIC) to a mixture obtained by mixing the following polymerizable liquid crystal compound A and polymerizable liquid crystal compound B at a mass ratio of 90:10, and polymerization initiation 6 parts of 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (“Irgacure 369 (Irg369)”, manufactured by BASF Japan Ltd.) was added as an agent.
Furthermore, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration was 13%, and the mixture was stirred at 80° C. for 1 hour to obtain a composition for forming a retardation layer.
Polymerizable liquid crystal compound A was produced by the method described in JP-A-2010-31223. Polymerizable liquid crystal compound B was produced according to the method described in JP-A-2009-173893. Each molecular structure is shown below.
[Polymerizable liquid crystal compound A]

[Polymerizable liquid crystal compound B]

[Production of Laminate Consisting of Base Material, Alignment Film, and Layer in which Polymerizable Liquid Crystal Compound is Cured]
Corona treatment was performed on a 50 μm-thick cyclic polyolefin film [trade name “ZF-14-50” manufactured by Nippon Zeon Co., Ltd.] as a substrate. A composition for forming an alignment film was applied to the corona-treated surface using a bar coater. The coating film of the alignment film-forming composition was dried at 80° C. for 1 minute. Using a polarized UV irradiation device (trade name “SPOT CURE SP-9” manufactured by Ushio Inc.), the coating film was irradiated with polarized UV at a wavelength of 313 nm at an integrated light amount of 100 mJ/cm ² at an axis angle of 45°. , to obtain an alignment film.

Subsequently, the retardation layer-forming composition was applied onto the alignment film using a bar coater and dried at 120° C. for 1 minute. Using a high-pressure mercury lamp (Ushio Inc., product name: "Unicure VB-15201BY-A"), the dried coating film is irradiated with ultraviolet rays (in a nitrogen atmosphere, integrated light intensity at a wavelength of 365 nm: 500 mJ/cm ² ). By doing so, the polymerizable liquid crystal compound was polymerized. In this way, a layered product comprising a base material, an alignment film, and a layer in which the polymerizable liquid crystal compound was cured was obtained.

The in-plane retardation value Re (λ) of the layer in which the polymerizable liquid crystal compound produced by the above method is cured is obtained by bonding the laminate to glass via an adhesive and peeling off the cyclic polyolefin film that is the base material. After that, it was measured with a measuring machine (trade name “KOBRA-WPR” manufactured by Oji Scientific Instruments Co., Ltd.). The measurement results of the retardation value Re (λ) at each wavelength are Re (450) = 121 nm, Re (550) = 142 nm, and Re (650) = 146 nm, and the layer in which the polymerizable liquid crystal compound is cured is a retardation film It functioned as Based on these values, Re(450)/Re(550)=0.85 and Re(650)/Re(550)=1.03 were calculated.

<Preparing the front plate>
A glass plate having a thickness of 0.4 mm manufactured by Corning was prepared.

[Example 1]
The protective film B was bonded to one surface of the polarizer A via the water-based adhesive, and the protective film A was bonded to the other surface via the water-based adhesive. After drying, a polarizing plate was produced. The moisture content of the polarizing plate was 1.11%.

The pressure-sensitive adhesive layer B was laminated on the protective film A of the polarizing plate, and the release film was peeled off.
The laminate was laminated on the exposed pressure-sensitive adhesive layer B so that the layer in which the polymerizable liquid crystal compound was cured became the bonding surface, and then the substrate was peeled off. Thus, a circularly polarizing plate composed of protective film B/polarizer A/protective film A/adhesive layer B/retardation film was produced.

[Examples 2-4, Comparative Examples 1-2]
A circularly polarizing plate was produced in the same manner, except that the moisture content of the polarizer, the protective film, and the polarizing plate was changed as shown in Table 1 below. The moisture content of the polarizing plate was adjusted by adjusting the drying temperature and drying time.

<Heat resistance test>
The pressure-sensitive adhesive layer A was laminated on the retardation film in the produced circularly polarizing plate. The release film was peeled off, and the circularly polarizing plate was laminated on the glass plate via the exposed pressure-sensitive adhesive layer A. Furthermore, the pressure-sensitive adhesive layer C was laminated on the protective film (first protective film) on the opposite side of the polarizing plate from the retardation film side. The release film was peeled off, and a front plate was laminated on the exposed pressure-sensitive adhesive layer C. Thus, an evaluation sample consisting of glass plate (front plate)/adhesive layer C/circularly polarizing plate/adhesive layer A/glass plate was produced.

A sample for evaluation was placed in an oven at 85° C. for 400 hours. The in-plane retardation values of the circularly polarizing plate before and after the insertion were measured, and the difference ΔRe was calculated. In addition, the retardation value was measured at the central portion in the plane of the circularly polarizing plate. The wavelength at which the in-plane retardation value was measured was 547 nm. Table 1 shows the above results. The circularly polarizing plates of Examples showed little decrease in the retardation value, and the reflected light was not colored after the heat resistance test. On the other hand, the circularly polarizing plate of the comparative example showed a large decrease in the retardation value, and the reflected light was colored red.

[Table 1]
────────────────────────────────────────
Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 ────────────────────────────────── ────────
First type BCC DEE
Protective film Moisture permeability 12 460 460 5.5 800 800
[g/ ^m2・24hr]
────────────────────────────────────────
Polarizer A B B B C D
────────────────────────────────────────
Second type A G F H E E
Protective film Moisture permeability 25 1210 35 1500 800 800
[g/ ^m2・24hr]
──────────────────────────────────────── Moisture content of polarizing plate [%] 1.11 2.11 1.92 1.70 3.10 3.70
────────────────────────────────────────
Sum of reciprocals of moisture permeability 1/x+1/y 0.1233 0.0030 0.0307 0.1825 0.0025 0.0025
──────────────────────────────────────── ΔRe [nm] 7.6 9.1 8.8 6.6 16.1 19.7
────────────────────────────────────────

According to the present invention, in the circularly polarizing plate provided with a retardation film containing a layer in which a liquid crystal compound is cured, the change in the color of reflected light from the initial stage after being placed in a high-temperature environment with the cover glass attached is It is useful because it can be suppressed.

1 Polarizing plate 2 Retardation film 3 Organic EL display element 4 Front plate 10 Polarizer 11 First protective film 12 Second protective film 13, 14, 16 Adhesive layer 15 Adhesive layers 20, 21 Polymerizable liquid crystal compound is cured layer

Claims (2)

a front plate;
a circularly polarizing plate;
A display device having a display element,
The circularly polarizing plate is
A retardation comprising a polarizing plate in which a first protective film is laminated on one surface of a polarizer and a second protective film is laminated on the other surface of the polarizer, and a layer in which a polymerizable liquid crystal compound is cured. comprising a film and
A circularly polarizing plate that satisfies the following conditions 1 and 2,
The first protective film is a cellulose resin,
The second protective film is a cyclic polyolefin resin,
Having an adhesive layer on the surface opposite to the polarizing plate in the retardation film,
The front plate is glass, and is provided on the opposite side of the polarizing plate to the side where the retardation film is laminated,
A display device bonded to the display element by the pressure-sensitive adhesive layer.
Condition 1: When the moisture permeability of the first protective film is x (g/m ² 24 hr) and the moisture permeability of the second protective film is y (g/m ² 24 hr), the formula ( 1) is satisfied.
1/x+1/y≧0.0030 Equation (1)
Condition 2: The moisture content of the polarizing plate is 3.00% or less. 2. The display device according to claim 1, wherein the polarizer has a thickness of 13 [mu]m or less.

Images