TW201943562A - Polarizing plate and display device - Google Patents

Abstract

The present invention provides a circular polarizing plate having a polarizing plate and a retardation film, wherein the retardation film comprises a retardation layer, the retardation film has a puncture elastic modulus of 15 gf/mm or more, the puncture elastic modulus is an elastic modulus measured in a test by using a needle having a tip diameter of 1 mm[Phi], 0.5 R with a puncture speed of 0.33 cm/sec.

Description

   Polarizing plate and display device   

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

In recent years, image display devices typified by organic electroluminescent (hereinafter also referred to as organic EL) display devices are rapidly spreading. In an organic electroluminescent (EL) display device, a circularly polarizing plate including a polarizer and a retardation film (λ / 4 plate) is mounted. By arranging a circular polarizer, it is possible to prevent the reflection of external light and improve the visibility of the screen.

With the rise of organic EL display devices, along with the demand for thinner image display devices, thinner circular polarizers are also required. A review is currently underway to change from "a retardation film formed from a conventional resin film" to "a retardation film formed using a thin liquid crystal compound as a material" (see, for example, Patent Document 1). A retardation film using a polymerizable liquid crystal compound is manufactured by applying a polymerizable liquid crystal compound on a substrate to align it, and irradiating light as needed to fix the alignment state. The circular polarizer having a retardation film formed of a polymerizable liquid crystal compound has a problem that the hue of the circular polarizer changes from the initial state to blue or red when it is placed in a high temperature environment. Specifically, when the circularly polarizing plate is rectangular, the hue of the reflected light near the four edges of the circularly polarizing plate becomes blue or red, respectively.

    [Prior technical literature]         [Patent Literature]    

[Patent Document 1] Japanese Patent Laid-Open No. 2017-54093

The object of the present invention is to solve the above problems. An object of the present invention is to provide a circularly polarizing plate provided with a retardation film, which is a circularly polarizing plate with small change in hue of reflected light before and after being placed in a high-temperature environment.

、0.5R的針並以穿刺速度為0.33cm/秒的測試所測定的彈性模數。 [1] A circular polarizing plate having a polarizing plate and a retardation film; wherein the retardation film includes a retardation layer; the puncture elastic modulus of the retardation film is 15 gf / mm or more; and the puncture elastic modulus is borrowed By using tip diameter of 1mm

Modulus of elasticity measured with a 0.5 R needle and a test at a puncture speed of 0.33 cm / sec.

[2] The circularly polarizing plate according to [1], wherein the circularly polarizing plate has an adhesive layer on its surface; the polarizing plate has a polarizer; and the retardation layer includes a layer cured by a polymerizable liquid crystal compound The aforementioned retardation film is disposed between the polarizing plate and the adhesive layer.

[3] The circularly polarizing plate according to [2], wherein the polarizer is formed of "a layer formed by curing a liquid crystal compound".

[4] The circular polarizing plate according to [2] or [3], wherein the shape of the circular polarizing plate is substantially rectangular; in the polarizing plate, the polarizer is opposite to the retardation film side The area layer has a protective film; the protective film is an extension film; the extending direction of the protective film is substantially parallel to the short-side direction of the circular polarizer.

[5] The circularly polarizing plate according to any one of [1] to [4], wherein the retardation film includes two retardation layers.

[6] A circularly polarizing plate with a front plate, which is obtained by laminating the circularly polarizing plate according to any one of [1] to [5] and the front plate with the front plate interposed therebetween.

[7] A display device comprising a circular polarizing plate as described in any one of [2] to [4] laminated on a display element via the aforementioned adhesive.

According to the present invention, it is possible to provide a circularly polarizing plate provided with a retardation film, which is a circularly polarizing plate with little change in hue of reflected light before and after being placed in a high-temperature environment.

1‧‧‧ polarizing plate

2‧‧‧ retardation film

3‧‧‧Organic EL Display Element

4‧‧‧ front panel

5 o'clock

10‧‧‧Polarizer

11, 12‧‧‧ protective film

13, 14, 16‧‧‧ Adhesive layer

15‧‧‧ Adjacent layer

20, 21‧‧‧ a layer hardened by a polymerizable liquid crystal compound

100, 101, 102, 103‧‧‧ circular polarizers

104, 105, 106‧‧‧ organic EL display devices

FIG. 1 is an example of a schematic cross-sectional view showing a layer configuration of a circularly polarizing plate.

FIG. 2 is an example of a schematic cross-sectional view showing a layer structure of an organic EL display device.

Figure 3 is a top view of a sample for evaluation.

<Circular polarizer>

The circular polarizing plate of the present invention includes a polarizing plate and a retardation film. The polarizing plate and the retardation film can be laminated, for example, via an adhesive layer. Examples of the adhesive layer include an adhesive layer and an adhesive layer described later. In the present invention, the polarizing plate refers to a laminated body composed of a polarizer and a protective film bonded to one or both sides of the polarizer.

Hereinafter, an example of the layer configuration of the circular polarizing plate of the present invention will be described with reference to FIG. 1. In addition, in FIG. 1, the adhesive layers used to adhere the polarizer 10 and the protective films 11 and 12 are not shown in the drawings. The circular polarizing plate 100 shown in FIG. 1 (a) has a layer structure in which a polarizing plate 1 and a retardation film 2 are laminated with an adhesive layer 13 interposed therebetween. The polarizing plate 1 is a first layer of a polarizer 10 and is protected. The film 11 includes a second protective film 12 on another area of the polarizer 10, and the retardation film 2 includes a layer 20 formed by curing a polymerizable liquid crystal compound. The circular polarizing plate 100 includes an adhesive layer 14 on a surface of the retardation film 2 opposite to the polarizing plate 1 side. The adhesive layer 14 may be an adhesive layer for bonding to an organic EL display element or the like.

The circular polarizing plate 101 shown in FIG. 1 (b) has a layered structure in which a polarizing plate 1 and a retardation film 2 are laminated with an adhesive layer 13 interposed therebetween. The polarizing plate 1 is a first layer of a polarizer 10 for protection. The film 11 includes a second protective film 12 on another area of the polarizer 10. In the circular polarizing plate 101, the retardation film 2 has a layer structure in which "a layer 20 made of a polymerizable liquid crystal compound is hardened" and "a layer 21 made of a polymerizable liquid crystal compound is hardened" with a layer 15 interposed therebetween. . The circular polarizing plate 101 includes an adhesive layer 14 on a surface of the retardation film 2 opposite to the polarizing plate 1 side. The adhesive layer 14 may be an adhesive layer for bonding to an organic EL display element or the like.

The circular polarizing plate 103 shown in FIG. 1 (c) has a layered structure in which a polarizing plate 1 and a retardation film 2 are laminated with an adhesive layer 13 interposed therebetween. The polarizing plate 1 is a first protective layer on an area of a polarizer 10. Film 11 persons. In the circular polarizing plate 103, the polarizing plate 1 has a protective film only on one side of the polarizer 10. In the circular polarizing plate 103, the retardation film 2 has a layer in which a "layer 20 made of a polymerizable liquid crystal compound is hardened" and a "layer 21 made of a polymerizable liquid crystal compound is hardened" with a layer 15 interposed therebetween. Make up. The circular polarizing plate 103 includes an adhesive layer 14 on a surface of the retardation film 2 opposite to the polarizing plate 1 side. The adhesive layer 14 may be an adhesive layer for bonding to an organic EL display element or the like.

The retardation film shown in FIG. 1 may have one retardation layer or two layers. Moreover, the retardation film may have an alignment film for aligning the polymerizable liquid crystal compound in its manufacturing stage. The polarizing plate shown in FIG. 1 may be provided with a protective film only on one area of the polarizer 10 or may be laminated on both sides.

The circular polarizing plate may have a layer other than the layer shown in FIG. 1. Examples of the layer system that the circular polarizing plate may further include a front panel, a light-shielding pattern, and the like. The front panel may be disposed on the side of the polarizing plate opposite to the side where the retardation film is laminated.

The light-shielding pattern may be formed on a polarizer-side surface of the front panel. The light-shielding pattern may be formed on a frame edge (non-display area) of the image display device so that the user does not see the wiring of the image display device.

The shape of the main surface of the circular polarizing plate may be substantially rectangular. The main surface is a surface having the largest area corresponding to the display surface. The term “substantially rectangular” refers to a shape in which at least one of the four corners (corners) is cut into an obtuse angle or a circular shape, or a part of the end surface perpendicular to the main surface has A recessed portion (notch) that is recessed in a plane direction, or a part of the main surface that has a perforated portion hollowed out into a shape such as a circle, an oval, a polygon, or a combination thereof.

The size of the circular polarizer is not particularly limited. When the circular 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 preferably 5 cm or more and 30 cm or less, and more preferably 6 cm or more and 25 cm or less.

<Polarizer>

In the present invention, the polarizing plate refers to a laminated body composed of a "polarizing member" and a "protective film adhered to one or both sides of the polarizing member". The protective film included in the polarizing plate may have a surface treatment layer such as a hard coat layer, an anti-reflection layer, and an antistatic layer described later. The polarizing plate and the protective film can be laminated, for example, via an adhesive layer and an adhesive. The components included in the polarizing plate will be described below.

(1) Polarizer

The polarizer included in the polarizing plate can be a linearly polarized light having "a linearly polarized light having a vibration plane parallel to its absorption axis and a vibration plane perpendicular to the absorption axis (parallel to the penetration axis) "Transmissive properties" are absorbing polarizers. The polarizer included in the first layer is preferably a polarizer made of a polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and aligned on one axis. The polarizer may include, for example, "a step of uniaxially extending a polyvinyl alcohol-based resin film", "a step of dyeing a polyvinyl alcohol-based resin film with a dichroic dye and adsorbing a dichroic dye", and The steps of processing a polyvinyl alcohol-based resin film that adsorbs a dichroic dye with a crosslinking solution such as an aqueous boric acid solution, and a method of "step of washing with a crosslinking solution after treatment" are produced.

As the polyvinyl alcohol-based resin film, one obtained by saponifying a polyvinyl acetate-based resin can be used. As for the polyvinyl acetate-based resin, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers of vinyl acetate and other monomers that can be copolymerized therewith can also be mentioned. The other monomers copolymerizable with vinyl acetate include, for example, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, (meth) acrylamidoamines having an ammonium group, and the like.

In this specification, "(meth) acrylic acid" means at least one selected from acrylic acid and methacrylic acid. The same meaning applies to "(meth) acrylfluorenyl" and "(meth) acrylate".

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, aldehyde-modified polyvinyl formal or polyvinyl acetal may be used. The average degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, and preferably 1500 to 5,000. The average degree of polymerization of the polyvinyl alcohol-based resin can be determined in accordance with JIS K6726.

A film formed of such a polyvinyl alcohol-based resin can be used as a raw material film of a polarizer. The method for forming a polyvinyl alcohol-based resin into a film is not particularly limited, and a conventional method can be adopted. The thickness of the polyvinyl alcohol-based raw material film is not particularly limited. In order to reduce the thickness of the polarizer to 15 μm or less, it is preferable to use 5 to 35 μm. It is more preferably 20 μm or less.

The uniaxial extension of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing of the dichroic pigment. In the case where one-axis extension is performed after dyeing, the one-axis extension may be performed before or during the crosslinking treatment. Moreover, one-axis extension may be performed in these plural stages.

In the case of one-axis extension, one-axis extension may be performed between rollers with different rotation speeds, or one-axis extension may be performed using a hot roller. In addition, the uniaxial stretching may be a dry stretching in the atmosphere, or a wet stretching in which the polyvinyl alcohol-based resin film is stretched in a swollen state using a solvent or water. The stretching 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 can be adopted. The dichroic pigment system uses iodine or a dichroic organic dye. The polyvinyl alcohol-based resin film is preferably subjected to an immersion treatment in which water is immersed before the dyeing treatment.

The cross-linking treatment after dichroic dyeing is generally performed by immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid. 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. The thickness of the polarizer is usually 2 μm or more, and preferably 3 μm or more. As a result of a review by the inventors, it can be seen that the change in the hue of the circularly polarizing plate is caused by the change in the retardation value of the retardation film. Furthermore, it can be seen that in a circularly polarizing plate placed in a high-temperature environment, the change in the retardation value of the retardation film is caused by the stress when the size of the polarizing plate shrinks. Therefore, from the viewpoint of reducing the influence caused by the shrinkage of the polarizer, if the thickness of the polarizer is set to 15 μm or less, it is effective in preventing the change in hue.

As for the polarizer, as described in Japanese Patent Application Laid-Open No. 2016-170368, it can be formed as a "layer hardened by a liquid crystal compound", and can be specifically used for alignment in a hardened film formed by polymerizing a liquid crystal compound. Those with dichroic pigments. As the dichroic pigment, those having an absorption in a wavelength range of 380 to 800 nm can be used. The dichroic pigment is preferably an organic dye. Examples of the dichroic pigment include an azo compound. The liquid crystal compound is a liquid crystal compound that can be polymerized in an aligned state, and may have a polymerizable group in the molecule. This type of polarizer is obtained by applying a composition containing a liquid crystal compound and a dichroic dye on an alignment film, and irradiating ultraviolet rays or heating as needed to fix the liquid crystal compound and the dichroic dye. Further, as described in International Publication Patent Publication WO2011 / 024891 or Japanese Patent Application Laid-Open No. 2018-120229, a polarizer can be formed from a dichroic dye having liquid crystallinity. In this way, if the polarizer is formed of a "layer hardened by a liquid crystal compound", it is helpful to reduce the dimensional change of the polarizer in a high-temperature environment, and it is effective in preventing color change.

When a polarizer including a "layer hardened by a liquid crystal compound" is used as the polarizer, the thickness of the polarizer may be 500 nm or more and 3 μm or less.

(2) Protective film

The circular polarizing plate of the present invention preferably has a protective film on at least one side of the polarizer, and more preferably has a protective film on the side of the polarizer opposite to the retardation film side. When the circular polarizing plate is substantially rectangular and the protective film is an extended film, it is preferable that the extending direction of the protective film and the short side direction of the circular polarizing plate are substantially parallel. When the circularly polarizing plate is substantially rectangular and the protective film is an unstretched film, it is preferable that the direction in which the tensile modulus of elasticity is the largest in the plane of the protective film is substantially parallel to the short-side direction of the circularly polarizing plate. If the extension direction (or the direction in which the tensile modulus of elasticity is the largest) and the short-side direction are such a relationship, regardless of the direction of the slow axis of the retardation film, the hue change of the circular polarizer tends to become smaller. When the extending direction of the protective film (or the direction in which the tensile modulus is the largest) is parallel to the short side, the extension of the polarizer and the protective film in a high-temperature environment is relaxed compared to when it is parallel to the long side. Since the shrinkage force in the extending direction of the protective film becomes smaller, it can be considered that the change in hue is smaller. The tensile elastic modulus is a value at 80 ° C, for example, measured by AUTOGRAPH (registered trademark) (manufactured by Shimadzu Corporation, model: AG-IS).

The extending direction of the protective film is substantially parallel to the short-side direction of the circular polarizer, and includes not only the case where the two are precisely parallel, but also the case where the angle formed by the two is 0 ± 10 °. The angle formed by the extending direction of the protective film and the short-side direction of the circular polarizer is preferably 0 ± 5 °. The "unstretched film" includes an unstretched film and a substantially unstretched film having a stretching ratio of 1.1 times or less.

The protective film laminated on both sides of the polarizer may be a film containing a thermoplastic resin having translucency (preferably optically transparent), and may be, for example, a film containing the following resin: a chain polyolefin resin (polypropylene Resins, etc.), cyclic polyolefin resins (norbornene resins, etc.), polyolefin resins, etc .; cellulose resins, such as triethylfluorene cellulose, diethylfluorene, and cellulose; Polyester resins such as ethylene formate and polybutylene terephthalate; polycarbonate resins; (meth) acrylic resins such as methyl methacrylate resins; polystyrene resins; polyvinyl chloride Vinyl resins; acrylonitrile‧butadiene‧styrene resins; acrylonitrile‧styrene resins; polyvinyl acetate resins; polyvinylidene chloride resins; polyamide resins; polyacetal resins; Modified polyphenylene ether resins; polyfluorene resins; polyether fluorene resins; polyarylate resins; polyamine imine resins; polyimide resins, etc.

Examples of the chain polyolefin resin include polyethylene resins (polyethylene resins which are homopolymers of ethylene, or copolymers mainly composed of ethylene), and polypropylene resins (homogenees which are homopolymers of propylene). In addition to homopolymers of chain olefins such as polypropylene resins of polymers or copolymers mainly composed of propylene), copolymers composed of two or more types of chain olefins can also be mentioned, for example.

The cyclic polyolefin resin is a general term for a resin polymerized by using a cyclic olefin as a polymerization unit. -122137 and other resins. To give specific examples of cyclic polyolefin resins, there are ring-opened (co) polymers of cyclic olefins, addition polymers of cyclic olefins, and copolymerization of cyclic olefins and chain olefins such as ethylene or propylene. Materials (representative examples are random copolymers), such graft polymers modified with unsaturated carboxylic acids or their derivatives, and these hydrides. Among them, a norbornene-based resin using a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer is preferred as the cyclic olefin.

The polyester resin is a resin having an ester bond excluding the cellulose ester resin described below, and is generally a polycondensate of a polycarboxylic acid or a derivative thereof with a polyhydric alcohol. The polycarboxylic acid or its derivative can be a dicarboxylic acid or its derivative, such as terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalate. For polyols, dihydric glycols such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, and cyclohexanedimethanol can be used. 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 mainly composed of a compound having a (meth) acrylfluorenyl group as a monomer. Specific examples of the (meth) acrylic resin include: poly (meth) acrylates such as polymethyl methacrylate; methyl methacrylate- (meth) acrylic copolymer; methyl methacrylate- ( (Meth) acrylate copolymer; methyl methacrylate-acrylate- (meth) acrylic acid copolymer; methyl methacrylate-styrene copolymer (MS resin, etc.); methyl methacrylate and alicyclic Copolymers of a group of hydrocarbon-based compounds (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth) acrylate copolymer, etc.). It is preferable to use a polymer containing poly (meth) acrylic acid C _1-6 alkyl ester such as poly (meth) acrylate as a main component, and more preferably a polymer containing methyl methacrylate as a main component (50 to 100). % By weight, preferably 70 to 100% by weight) of a methyl methacrylate resin.

The cellulose ester resin is an ester made of cellulose and a fatty acid. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. In addition, for example, such copolymers or those in which a part of the hydroxyl group is modified with another substituent may be mentioned. Among these, cellulose triacetate (ie, triethylfluorenyl cellulose) is particularly preferred.

Polycarbonate resins are engineering plastics containing "polymers that bond monomer units through carbonate groups."

It is also useful if the phase difference value of the protective film is adjusted to a value that is better for an image display device such as a liquid crystal display device. For example, in a liquid crystal display device in an IPS (in-plane switching, lateral electric field effect display technology) mode, it is preferable to use a film having a substantially zero phase difference value as the protective film. The 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. Moreover, in order to improve the visibility of the picture when the user wears polarized sunglasses, 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 subjected to extension and / or contraction processing, etc., so as to provide a suitable retardation. For example, for the purpose of viewing angle compensation, a single-layer or multi-layer structure can be used as the protective film.

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

The protective film attached to one or both sides of the polarizer may be made of the same type of thermoplastic resin, or may be made of different types of thermoplastic resin. The thicknesses may be the same or different. Furthermore, they may have the same phase difference characteristic, or they may have different phase difference characteristics.

As described above, at least one of the protective films may include, for example, a hard coat layer, an anti-glare layer, a light diffusion layer, an anti-reflection layer, a low refractive index layer, and the like on its outer surface (the surface opposite to the polarizer side), Surface treatment layer (coating layer) such as antistatic layer or antifouling layer. The thickness of the protective film includes the thickness of the surface treatment layer.

The protective film can be bonded to a polarizer via, for example, an adhesive layer or an adhesive layer. As the adhesive system forming the adhesive layer, a water-based adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used, and a water-based adhesive or an active energy ray-curable adhesive is preferable. As the adhesive layer, the latter can be used.

Examples of the water-based adhesive include an adhesive composed of a polyvinyl alcohol-based resin aqueous solution, and a water-based two-liquid amine ester-based latex adhesive. Among them, a water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution is suitably used. As for the polyvinyl alcohol-based resin, in addition to the polyvinyl alcohol homopolymer obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, vinyl acetate and possibly A polyvinyl alcohol-based copolymer obtained by saponifying a copolymer of another monomer copolymerized therewith, or a modified polyvinyl alcohol-based polymer obtained by partially modifying these hydroxyl groups. The water-based adhesive may include a crosslinking agent such as an aldehyde compound (for example, glyoxal, etc.), an epoxy compound, a melamine compound, a methylol compound, an isocyanate compound, an amine compound, or a polyvalent metal salt.

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

The above-mentioned active energy ray-curable adhesive refers to 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-curable adhesive.

The curable compound may be a cation polymerizable curable compound or a radical polymerizable curable compound. Examples of the cationically polymerizable sclerosing compound include epoxy compounds (compounds having one or two or more epoxy groups in the molecule), and oxetane compounds (having one or two or more molecules in the molecule). Oxetanyl compound), or a combination of these. Examples of the radically polymerizable sclerosing compound include (meth) acrylic compounds (compounds having one or two (meth) acryloxy groups in the molecule), and radically polymerizable double bonds. Other vinyl compounds, or a combination of these. A cationically polymerizable curable compound and a radical polymerizable curable compound may be used in combination. The active energy ray-curable adhesive usually further includes a cationic polymerization initiator and / or a radical polymerization initiator for initiating a curing reaction of the curable compound.

When the polarizer and the protective film are bonded, a surface activation treatment may be performed on the bonding surface of at least one of them in order to improve adhesion. Surface activation treatments can include, for example, dry treatments such as corona treatment, plasma treatment, discharge treatment (arc discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, and ionizing radiation treatment (ultraviolet treatment, electron beam treatment, etc.) ; Such as water, acetone and other solvents such as ultrasonic treatment, saponification treatment and anchor treatment. These surface activation treatments may be performed alone or in combination of two or more.

When the protective film is laminated on both sides of the polarizer, the adhesive used to adhere the protective film may be the same type of adhesive, or different types of adhesives.

Instead of the protective film, a protective layer may be formed on one side of the polarizer. The protective layer may be formed on the polarizer without the adhesive layer and the adhesive layer. That is, the protective layer may be formed in contact with the polarizer. The protective layer may be a layer containing a (meth) acrylic resin or a layer containing an aqueous resin.

The layer containing a (meth) acrylic resin can be obtained by applying a composition containing a (meth) acrylic resin to a polarizer and heating or irradiating an active energy ray, or the layer containing (meth) ) The composition of an acrylic resin is formed by coating on a base film and heating or irradiating active energy rays. In the latter case, a polarizer can be formed on a layer containing a (meth) acrylic resin.

The (meth) acrylic resin refers to a polymer containing, as a main component, a monomer having a (meth) acrylfluorene group among monomers constituting the (meth) acrylic resin. Here, the main component refers to a monomer having a maximum content (% by mass) among the monomer components constituting the (meth) acrylic resin. When a (meth) acrylic resin is used as a material for forming the protective layer, degradation of the optical characteristics of the circularly polarizing plate can be suppressed even in a hot and humid environment.

The (meth) acrylic resin is preferably polymerized from a photopolymerizable monomer, and may be, for example, a monofunctional monomer or a polyfunctional monomer having a (meth) acrylfluorene group. Or two or more kinds are mixed and polymerized. The (meth) acrylic resin can polymerize a monomer other than a monomer having a (meth) acrylfluorene group, and for example, a monomer having a vinyl group can be polymerized.

The single system having a (meth) acrylfluorenyl group is not particularly limited, and examples thereof include compounds having one or two or more (meth) acrylfluorenyl groups in the molecule. These may be used alone or in combination of two or more. use. Specifically, for example, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, pentaerythritol tetra (meth) acrylate, bis (trimethylolpropane) tetra (methyl) Acrylates, ethylene oxide or propylene oxide addition compounds of the above (meth) acrylates; oligoesters (meth) acrylates, oligomers having at least 4 (meth) acrylfluorenyl groups in the molecule Ether (meth) acrylate, oligomeric urethane (meth) acrylate, oligomeric epoxy (meth) acrylate, oligomeric melamine (meth) acrylate, polyfunctional acrylate with dendrimer structure Wait.

The thickness of the (meth) acrylic resin-containing layer 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, preferably 15 μm or less, and more preferably 10 μm. the following. If the thickness of the layer containing a (meth) acrylic-type resin is in the said range, a bendable circular polarizing plate will be obtained easily.

The layer containing the water-based resin may be formed by applying a composition containing a water-based resin to a polarizer and heating or irradiating active energy rays, or it may be performed by coating a composition containing a water-based resin on a substrate film and It is formed by heating or irradiating active energy rays. In the latter case, a polarizer can be formed on a layer containing an aqueous resin.

Examples of the water-based resin include water-soluble polymers such as polyvinyl alcohol, ethylene vinyl acetate copolymer, polyvinyl pyrrolidone, starches, methyl cellulose, carboxymethyl cellulose, and sodium alginate. Vinyl alcohol is preferred.

The thickness of the water-based resin-containing layer is preferably 0.1 μm or more, more preferably 0.3 μm or more, more preferably 3 μm or less, more preferably 1.5 μm or less, and still more preferably 1 μm or less. When the thickness of the layer containing the water-based resin is within the above range, a bendable circular polarizing plate can be easily obtained.

The protective layer may be a single layer or a plurality of layers. In the case where the protective layer is formed by a plurality of layers, the protective layer may be, for example, a layer containing a (meth) acrylic resin and a layer containing a water-based resin. The appearance of a laminated body.

<Phase retardation film>

The circular polarizing plate of the present invention includes a retardation film. The puncture elastic modulus of the retardation film is 15 gf / mm or more, preferably 20 gf / mm or more, more preferably 25 gf / mm or more, and even more preferably 30 gf / mm or more. The upper limit of the puncture elastic modulus of the retardation film is not particularly limited, and may be, for example, 200 gf / mm or less, or 50 gf / mm or less. A retardation film having a puncture elastic modulus in such a range tends to be difficult to cause a change in retardation value in a high-temperature environment. When the puncture elastic modulus is larger, the phase difference value is less likely to change with respect to the stress caused by the dimensional shrinkage of the polarizing plate.

When the retardation film includes one retardation layer, the puncture elastic modulus of the retardation film is 15 gf / mm or more, preferably 20 gf / mm or more, more preferably 25 gf / mm or more, and still more preferably 30 gf / mm or more . The upper limit of the puncture elastic modulus of the retardation film is not particularly limited, and may be, for example, 200 gf / mm or less, 90 gf / mm or less, or 50 gf / mm or less.

When the retardation film includes two retardation layers, the puncture elastic modulus of the retardation film is 30 gf / mm or more, preferably 40 gf / mm or more, more preferably 50 gf / mm or more, and particularly preferably 70 gf / mm or more. The upper limit of the puncture elastic modulus of the retardation film is not particularly limited, and may be, for example, 200 gf / mm or less, 150 gf / mm or less, or 100 gf / mm or less.

、0.5R者。針穿刺的速度可為0.33cm/秒。穿刺彈性模數的測定，係在具有可通過針的直徑15mm以下的圓形開孔之2片板之間夾住相位差膜而進行。穿刺彈性模數的測定，可在溫度23℃的環境下進行。例如可對5片相位差膜測定穿刺彈性模數，以其平均值作為相位差膜的穿刺彈性模數。穿刺彈性模數的測定可利用市售的裝置。市售的裝置可舉例如KATO TECH股份有限公司製的便攜式壓縮測試機”KES-G5針穿透力測定規範”、島津製作所股份有限公司製的小型桌上測試機”EZ Test”等。 The puncture elastic modulus refers to the force (gf) before the retardation film breaks (or ruptures) divided by the strain (mm) at the time when the main surface of the retardation film is punctured vertically with a needle (puncture jig). The value obtained. Needle can be used with a tip diameter of 1mm

, 0.5R. The speed of needle puncture can be 0.33 cm / sec. The measurement of the puncture elastic modulus is performed by sandwiching a retardation film between two plates having a circular opening with a diameter of 15 mm or less that can pass through a needle. The measurement of the puncture elastic modulus can be performed in an environment at a temperature of 23 ° C. For example, the puncture elastic modulus of five retardation films can be measured, and the average value can be used as the puncture elastic modulus of the retardation film. A commercially available device can be used for the measurement of the puncture elastic modulus. Commercially available devices include, for example, a portable compression tester "KES-G5 Needle Penetration Measurement Standard" manufactured by KATO TECH Corporation, and a small desktop tester "EZ Test" manufactured by Shimadzu Corporation.

The puncture elastic modulus of the retardation film can be controlled by adjusting, for example, the type of polymerizable liquid crystal compound or alignment film used, the degree of hardening of the polymerizable liquid crystal compound, the thickness of the retardation film, and the like.

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 a composition containing a polymerizable liquid crystal compound specifically means a layer obtained by curing a polymerizable liquid crystal compound. In this specification, a layer giving a retardation of λ / 2, a layer giving a retardation of λ / 4 (positive A layer), and a positive C layer are collectively referred to as a retardation layer. The retardation film may include an alignment film described later.

The layer giving a retardation of λ / 2 preferably 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. The layer giving a retardation of λ / 4 is preferably 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. The positive C layer may be a layer having a refractive index showing a relationship of nx ≒ ny <nz. The phase difference in the thickness direction of the positive C layer may be -50 nm to -150 nm and -70 nm to -120 nm at a wavelength of 550 nm.

A layer formed by curing a polymerizable liquid crystal compound is formed on, for example, an alignment film provided on a substrate. The substrate may have a function of supporting an alignment film, and may be a substrate formed in a long shape. This substrate functions as a release support, and can support a transferred retardation layer. Furthermore, it is preferable that the surface has a peeling degree of adhesion. The substrate may be, for example, a resin film exemplified as a material of the protective film.

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

Furthermore, various anti-blocking treatments can be performed on the substrate. Examples of the anti-caking treatment include an easy-adhesion treatment, a treatment of kneading a filler, and the like, and an embossing treatment (such as a knurling treatment). By applying such an anti-blocking treatment to the base material, it is possible to effectively prevent the base materials from adhering to each other (that is, the so-called blocking) when the base material is wound up, and to produce an optical film with high productivity.

A layer formed by curing a polymerizable liquid crystal compound is formed on a substrate via an alignment film. That is, a base material and an alignment film are sequentially laminated, and a layer system formed by curing a polymerizable liquid crystal compound is laminated on the alignment film.

The alignment film is not limited to a vertical alignment film, and may be an alignment film in which the molecular axis of the polymerizable liquid crystal compound is horizontally aligned, or an alignment film in which the molecular axis of the polymerizable liquid crystal compound is inclined. The alignment film preferably has solvent resistance that does not dissolve due to application of a composition including a polymerizable liquid crystal compound described later, and heat resistance during heat treatment for removing the solvent or alignment liquid crystal compound. Sex. Examples of the alignment film include an alignment film containing an alignment polymer, a photo-alignment film, and a groove alignment film having an uneven shape or a plurality of grooves formed on the surface and aligned. The thickness of the alignment film is usually in a range of 10 nm to 10,000 nm, preferably in a range of 10 nm to 1000 nm, more preferably in a range of 500 nm or less, and even more preferably in a range of 10 nm to 200 nm. When the retardation film has an alignment film, if the thickness of the alignment film is increased, it is easy to increase the puncture elastic modulus.

An alignment film containing an alignment polymer is usually formed by applying a composition in which an alignment polymer is dissolved in a solvent to a substrate and removing the solvent, or applying a composition of an alignment polymer to a substrate. It was obtained by removing the solvent and rubbing (friction method). Examples of the alignment polymer include polyamines or gelatins having a fluorene bond in the molecule, polyfluorenes having a fluorimine bond in the molecule, and polyamic acid, polyvinyl alcohol, and alkylene which are hydrolyzates thereof. Modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylates. Among these, polyvinyl alcohol is preferred. The alignment polymer may be used alone or in combination of two or more.

The photo-alignment film is generally obtained by applying a composition containing a photoreactive polymer or monomer and a solvent to a substrate, removing the solvent, and then irradiating polarized light (preferably polarized UV). The light alignment film is advantageous because the direction of the alignment control force can be arbitrarily controlled by selecting the polarization direction of the polarized light to be irradiated.

The photo-reactive group refers to a group that generates liquid crystal alignment ability by light irradiation. Specifically, for example, a group that can participate in "a photoreaction that becomes a source of the alignment ability of a liquid crystal, such as an alignment initiation or isomerization reaction, a dimerization reaction, a photocrosslinking reaction, or a photodecomposition reaction of molecules generated by light irradiation" can be mentioned. . Among them, from the viewpoint of good alignment, it is preferred that the group participates in a dimerization reaction or a photocrosslinking reaction. The photoreactive group is preferably a group having an unsaturated bond (especially a double bond), and particularly preferably a group selected from a carbon-carbon double bond (C = C bond) and a carbon-nitrogen double bond (C = N bond), a nitrogen-nitrogen double bond (N = N bond), and a carbon-oxygen double bond (C = O bond).

(formazan)基及氧偶氮基苯(azoxybenzene)結構的基等。具有C=O鍵的光反應性基，可舉例如二苯甲酮(benzophenone)基、香豆素(coumarin)基、蒽醌基及馬來醯亞胺基等。該等基可具有烷基、烷氧基、芳基、烯丙基氧基、氰基、烷氧基羰基、羥基、磺酸基、鹵代烷基等取代基。 Examples of the photoreactive group having a C = C bond include a vinyl group, a polyalkenyl group, a distyryl group, a stilbazole group, a stilbazolium group, a chalcone group, Cinnamon and other bases. Examples of the photoreactive group having a C = N bond include a group 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 azophenyl group, an azonaphthyl group, an aromatic heterocyclic azo group, a bisazo group, and a methyl group.

(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 maleimidine group. These groups may have substituents such as alkyl, alkoxy, aryl, allyloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonic acid, and haloalkyl.

Among them, a photoreactive group that participates in photodimerization is preferred, and because the amount of polarized light irradiation required for photoalignment is small and a photoalignment film with good thermal stability and time stability is easily obtained, cinnamon is used Amidino and chalcone are preferred. In the case of a polymer having a photoreactive group, it is particularly preferable that the end of the side chain of the polymer has a cinnamic acid group having a cinnamic acid structure.

The type of the polymerizable liquid crystal compound used in this embodiment is not particularly limited, and can be classified into a rod-like type (rod-like liquid crystal compound) and a disk-like type (disk-like liquid crystal compound, disk-like liquid crystal) by its shape Compound). Furthermore, there are each a low molecular type and a high molecular type. The term "polymer" generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physical Phase Transition Kinetics, Masahiro Doi, 2 pages, Iwanami Bookstore, 1992).

In this embodiment, any polymerizable liquid crystal compound can be used. Furthermore, two or more rod-like liquid crystal compounds, two or more disc-shaped liquid crystal compounds, or a mixture of a rod-like liquid crystal compound and a disc-shaped liquid crystal compound may be used.

The rod-shaped liquid crystal compound can be suitably used, for example, as described in claim 1 of Japanese Patent Application Publication No. 11-513019 or paragraphs [0026] to [0098] of Japanese Patent Application Publication No. 2005-289980. As the discotic liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of Japanese Patent Application Laid-Open No. 2007-108732 or paragraphs [0013] to [0108] of Japanese Patent Laid-Open No. 2010-244038 can be suitably used.

The polymerizable liquid crystal compound may be used in combination of two or more. In this case, at least one species has two or more polymerizable groups in the molecule. That is, the layer hardened by the polymerizable liquid crystal compound is preferably a layer formed by polymerizing and fixing a liquid crystal compound having a polymerizable group. In this case, it is not necessary to display liquid crystal properties after the layer is formed.

The polymerizable liquid crystal compound has a polymerizable group capable of performing a polymerization reaction. The polymerizable group is preferably a functional group capable of performing an addition polymerization reaction such as a polymerizable ethylenically unsaturated group and a cyclic polymerizable group. More specifically, examples of the polymerizable group include (meth) acrylfluorenyl, vinyl, styryl, and allyl. Among them, a (meth) acrylfluorenyl group is preferred. It is to be noted that the (meth) acrylfluorenyl group includes both a methacrylfluorenyl group and an acrylfluorenyl group.

As described later, a layer made of a polymerizable liquid crystal compound can be formed by applying a composition containing a polymerizable liquid crystal compound to, for example, an alignment film and irradiating active energy rays. The composition may contain components other than the polymerizable liquid crystal compound. For example, the aforementioned composition preferably contains a polymerization initiator. The polymerization initiator used is selected according to the type of the polymerization reaction, for example, a thermal polymerization initiator and a photopolymerization initiator. For example, the photopolymerization initiator may be, for example, an α-carbonyl compound, an acyloin ether, an α-hydrocarbon substituted aromatic alcohol ketone compound, a polynuclear quinone compound, a triarylimidazole dimer, and a p-aminophenyl ketone. combination. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, and more preferably 0.5 to 5% by mass, with respect to the entire solid content in the coating solution.

The composition may contain a polymerizable monomer from the viewpoint of the uniformity of the coating film and the strength of the film. Examples of the polymerizable monomer include a radical polymerizable compound and a cation polymerizable compound. Among these, a polyfunctional radical polymerizable monomer is preferable.

The polymerizable monomer is preferably one that can be copolymerized with the polymerizable liquid crystal compound. The usage-amount of a polymerizable monomer is 1-50 mass% with respect to the whole mass of a polymerizable liquid crystal compound, More preferably, it is 2-30 mass%.

Further, the composition may contain a surfactant from the viewpoint of the uniformity of the coating film and the strength of the film. Examples of the surfactant include conventionally known compounds. Among them, particularly preferred is a fluorine-based compound.

In addition, a solvent may be contained in the aforementioned composition, and an organic solvent is preferably used. Examples of the organic solvent include fluorene (e.g., N, N-dimethylformamide), fluorene (e.g., dimethyl sulfene), heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g., benzene, hexane), halogenated Alkanes (e.g. chloroform, dichloromethane), esters (e.g. methyl acetate, ethyl acetate, butyl acetate), ketones (e.g. acetone, methyl ethyl ketone), ethers (e.g. tetrahydrofuran, 1,2-dimethoxy) Ethane). Among them, alkyl halides and ketones are preferred. Further, two or more organic solvents may be used in combination.

In addition, the foregoing composition may include a vertical alignment accelerator such as a polarizer interface-side vertical alignment agent, an air interface side vertical alignment agent, and a polarizer interface-side horizontal alignment agent, an air interface-side horizontal alignment agent, and the like. Of various alignment agents. In addition, the composition may include, in addition to the above-mentioned components, an adhesion improver, a plasticizer, a polymer, and the like.

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

The irradiation intensity of ultraviolet rays is usually 100 mW / cm ² to 3,000 mW / cm ² . The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activation of a photocationic polymerization initiator and a photoradical polymerization initiator. The time for irradiating ultraviolet rays is usually from 0.1 seconds to 10 minutes, preferably from 0.1 seconds to 5 minutes, more preferably from 0.1 seconds to 3 minutes, and even more preferably from 0.1 seconds to 1 minute.

Ultraviolet rays can be irradiated once or divided into multiple times. The ultraviolet irradiation is preferably performed a plurality of times. When the liquid crystal compound has a high polymerization rate, its puncture elastic modulus is easily increased to the range of the present invention. Although depending on the polymerization initiator used, the cumulative light amount at a wavelength of 365 nm is preferably 700 mJ / cm ² or more, more preferably 1,100 mJ / cm ² or more, and even more preferably 1,300 mJ / cm ² or more. If it is the said accumulated light quantity, it will be conducive to the improvement of the polymerization rate of the polymerizable liquid crystal compound which comprises a retardation film, and it will greatly increase the puncture elastic modulus of a retardation film. The cumulative amount of light at a wavelength of 365 nm is preferably 2,000 mJ / cm ² or less, and more preferably 1,800 mJ / cm ² or less. If it is the said accumulated light quantity, coloring of a retardation film may be caused.

Furthermore, in order to prevent the alignment of the liquid crystal compound from being disturbed by the heat immediately after the ultraviolet rays are irradiated, it is preferable to provide a cooling step after the ultraviolet rays are irradiated. By providing a cooling step after the ultraviolet irradiation, the alignment of the liquid crystal compound can be suppressed from being disturbed by the heat generated immediately after the irradiation. As a result, the degree of alignment of the liquid crystal compound is increased, and a film having higher rigidity can be obtained. The cooling temperature may be, for example, 20 ° C or lower, and may be 10 ° C or lower. The cooling time may be, for example, 10 seconds or more, and may be 20 seconds or more.

In this 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, and more preferably 5 μm or less. The above-mentioned upper limit value and lower limit value can be arbitrarily combined. When the thickness of the retardation layer is not less than the aforementioned lower limit, sufficient durability can be obtained. When the thickness of the retardation layer is equal to or less than the aforementioned upper limit value, it can contribute to the thinning of the circular polarizing plate. The thickness of the retardation layer can be adjusted to obtain a desired in-plane retardation value and a thickness direction retardation value in a layer giving a retardation of λ / 4, a layer giving a retardation of λ / 2, or a positive C layer.

The retardation film may be a "layer hardened from a polymerizable liquid crystal compound" including one layer, or a "layer hardened from a polymerizable liquid crystal compound" including two or more layers. When the retardation film includes two layers of a polymerizable liquid crystal compound hardened, it is preferable that the two layers are a combination of a layer giving a retardation of λ / 4 and a positive C layer, or a combination of a positive C layer. A combination of a phase difference layer and a layer giving a phase difference of λ / 2. When the retardation film includes two layers of a polymerizable liquid crystal compound hardened, a layer of a polymerizable liquid crystal compound hardened can be separately prepared on the alignment film, and the two are separated by an adhesive layer or an adhesive. A layer may be laminated to produce a retardation film, or a layer formed by curing a polymerizable liquid crystal compound may be formed on a layer formed by curing a polymerizable liquid crystal compound. After the two are laminated, the substrate and the alignment film can be peeled off. The thickness of the retardation film is preferably 3 to 30 μm, and more preferably 5 to 25 μm.

<Adhesive layer>

The adhesive layer may be composed of an adhesive composition containing (meth) acrylic, rubber, urethane, ester, silicone, polyvinyl ether or the like as a main component. Among them, an adhesive composition containing a (meth) acrylic resin excellent in transparency, weather resistance, heat resistance and the like as a base polymer is suitable. The adhesive composition may be an active energy ray hardening type or a thermosetting type. The thickness of the adhesive layer is usually 3 to 30 μm, and preferably 3 to 25 μm.

Regarding the (meth) acrylic resin (matrix polymer) used in the adhesive composition, it is suitable to use, for example, butyl (meth) acrylate, ethyl (meth) acrylate, and isooctyl (meth) acrylate. A polymer or copolymer of one or two or more (meth) acrylates such as 2-ethylhexyl (meth) acrylate and the like. In the matrix polymer, a polar monomer is preferably copolymerized. Examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylamide, and N, N-dimethylaminoethyl. Monomers having a carboxyl group, a hydroxyl group, a amine group, an amine group, an epoxy group, and the like, such as a methyl (meth) acrylate and a glycidyl (meth) acrylate.

The adhesive composition may include only the matrix polymer described above, but usually further contains a crosslinking agent. Examples of the cross-linking agent include: metal ions having a valence of two or more, which form a metal carboxylic acid salt with a carboxyl group; polyamine compounds, which form an amine bond with a carboxyl group; a polyepoxide compound, or Polyol, which forms an ester bond with the carboxyl group; polyisocyanate compounds, which forms an amido bond between the system and the carboxyl group. Among these, a polyisocyanate compound is preferable.

<Front panel>

The present invention includes a circular polarizer with a front panel, which is formed by laminating a circular polarizer and a front panel with an adhesive layer therebetween. The front panel is arranged on the viewing side of the polarizing plate. The front panel may be laminated on the polarizing plate via an adhesive layer. Examples of the adhesive layer include the aforementioned adhesive layer and adhesive layer. As shown in FIGS. 2 (a), (b), and (c), the front panel 4 is laminated on the protective film 11 of the polarizing plate 1 via an adhesive layer 16.

The front panel may include, for example, a hard coat layer on at least one side of glass or resin film. As the glass, for example, high-penetration glass and tempered glass can be used. In particular, when a thin transparent material is used, chemically strengthened glass is preferred. The thickness of the glass may be, for example, 100 μm to 5 mm.

The front panel formed by including a hard coating layer on at least one side of the resin film is not as hard as conventional glass and may be flexible. The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 to 100 μm.

The resin film may be a film formed of a cycloolefin-based derivative having a unit containing a cycloolefin-containing monomer such as norbornene or a polycyclic norbornene-based monomer, and cellulose (diethylfluorenyl). (Cellulose, triethyl cellulose, ethyl cellulose butyrate, isobutyl cellulose, propyl cellulose, butyl cellulose, ethoxypropyl cellulose) ethylene-vinyl acetate copolymerization Polymer, polycyclic olefin, polyester, polystyrene, polyimide, polyetherimide, polyacrylic acid, polyimide, polyimide, imine, polyether, polyimide, polyethylene, polypropylene , Polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether fluorene, polymethyl methacrylate, polypair Polymers such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, and epoxy resin. As the resin film, an unstretched, uniaxially or biaxially stretched film can be used. These polymers may be used singly or in combination of two or more kinds. The resin film is preferably a polyimide film or a polyimide film excellent in transparency and heat resistance, and a polyester film stretched in one or two axes. A large-sized cycloolefin derivative film, a polymethyl methacrylate film, and a triethylfluorene cellulose and isobutyl cellulose film having transparency and no optical anisotropy. The thickness of the resin film is 5 to 200 μm, and preferably 20 to 100 μm.

The hard coat layer can be formed by hardening a hard coat composition containing a reactive material that forms a crosslinked structure by irradiation with light or thermal energy. The hard coat layer can be formed by hardening a hard coating composition containing both a photocurable (meth) acrylate monomer or oligomer and a photocurable epoxy monomer or oligomer. The photo-curable (meth) acrylate monomer may include one selected from the group consisting of an epoxy (meth) acrylate, an amine (meth) acrylate, and a polyester (meth) acrylate. 1 or more. The epoxy (meth) acrylate can be obtained by reacting a (meth) acrylfluorenyl carboxylic acid with an epoxy compound.

The hard coating composition may further include one or more members selected from the group consisting of a photoinitiator and an additive. The additive may include one or more selected from the group consisting of inorganic nano particles, a leveling agent, and a stabilizer. In addition, each component system generally used in the technical field may include, for example, an antioxidant, a UV absorber, and an interface. Active agents, lubricants, antifouling agents, etc.

<Shading Pattern>

The light-shielding pattern can provide at least a part of a bezel or housing of a front panel or a display device suitable for the front panel. The light-shielding pattern may be formed on the display element side of the front panel. The light-shielding pattern can hide each wiring of the display device and prevent the user from seeing it. The color and / or material of the light-shielding pattern is not particularly limited, and it can be formed from resin materials having various colors such as black, white, and gold. In one embodiment, the thickness of the light-shielding pattern may be in a range of 2 μm to 50 μm, preferably 4 μm to 30 μm, and more preferably 6 μm to 15 μm. Further, in order to suppress the inclusion of bubbles due to the step between the light-shielding pattern and the display portion and the recognition of the boundary portion, a shape may be provided to the light-shielding pattern.

<Manufacturing method of circular polarizing plate>

Taking the circular polarizing plate 100 shown in FIG. 1 (a) as an example, a method for manufacturing the circular polarizing plate will be described. The circularly polarizing plate 100 can be manufactured by laminating the polarizing plate 1 and the retardation film 2 via an adhesive layer 13.

The polarizing plate 1 can be manufactured by laminating the polarizer 10 and the protective films 11 and 12 via an adhesive, respectively. For a polarizing plate, a long member can be prepared, and the members can be manufactured by rolling to roll, and then cut into a specified shape, and each member can also be cut to a specified Shape after fitting. After the polarizer 10 is bonded to the protective films 11 and 12, a heating step and a humidity adjustment step may be provided.

The retardation film 2 can be manufactured using the following method, for example. An alignment film is formed on the substrate, and a coating liquid containing a polymerizable liquid crystal compound is applied on the alignment film. In a state where the polymerizable liquid crystal compound is aligned, the active energy ray is irradiated to harden the polymerizable liquid crystal compound. An adhesive layer 14 formed on a release film is laminated on a layer made of a polymerizable liquid crystal compound. Then, the substrate and / or the alignment film are peeled off. Next, on the protective film 12, an adhesive layer 13 formed on the release film is laminated. As for the retardation film 2, a long member can be prepared, and the members can be laminated to each other in a roll-to-roll manner, and then cut into a predetermined shape and manufactured. Alternatively, each member can be cut into a predetermined shape and pasted. Together.

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

After the heat resistance test, the difference in color recognized in the surface of the circular polarizer on the reflective plate can be reduced by uniformizing the reflection hue in the surface of the circular polarizer after the heat resistance test. In order to uniformize the reflection hue in the surface of the circularly polarizing plate after the heat resistance test, the necessary elements can be, for example, the reflection hue in the surface of the circularly polarizing plate before the heat resistance test is uniform and the change in the reflection hue before and after the heat resistance test is small.

If the hue of the reflected light before the heat-resistance test of the circularly polarizing plate is uniform in the plane, the hue difference of the hue of the reflected light in the plane of the circle-polarizing plate after the heat-resistance test is reduced, which is preferable. Specifically, the color tone of the reflected light in the center (may be the center of gravity or the center point 5 shown in Fig. 3) on the main surface before the heat resistance test, and the portion other than the center in the main surface (for example, The difference in the color tone of the reflected light at point 5 except for the center shown in Fig. 3) is preferably 1.0 or less, more preferably 0.8 or less, and still more preferably 0.6 or less. The difference in hue of the reflected light between the central portion and the other portions can be calculated by, for example, the following formula.

Difference △ a * b * = [( △ a *) 2 + (△ b *) 2] 1/2 where, △ a * other than the central portion of the a * and the central portion of the a *, △ b * Is the difference corresponding to b *. If the uniformity of the hue of the reflected light in the surface of the circularly polarizing plate before the heat resistance test is low, the effect of improving the visibility may be reduced even if the hue change of the reflected light before and after the heat resistance is small. The heat resistance test can be performed, for example, by storing the circularly polarizing plate in a dryer set at 80 ° C. for 168 hours.

〈Use〉

The circular polarizing plate can be used in various display devices. The display device refers to a device having a display element, which 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 electroluminescent (hereinafter also referred to as an inorganic EL device) display device, an electron emission display device (such as an electric field emission display device (also referred to as a FED), and a surface electric field emission). Display device (also known as SED)), electronic paper (display device using electronic ink or electrophoretic element), plasma display device, projection display device (e.g., grating light valve (also called GLV) display device , A display device with a digital micromirror device (also called a DMD), and a piezoelectric ceramic display. The liquid crystal display device also includes any of a transmissive liquid crystal display device and a semi-transmissive liquid crystal display device. These display devices may be display devices that display two-dimensional images, or stereoscopic display devices that display three-dimensional images. The circular polarizing plate system is particularly effective for use in an organic EL display device or an inorganic EL display device.

In FIGS. 2 (a) and 2 (b), the organic EL display devices 104 and 105 have a layer structure in which a circular polarizing plate is laminated on the organic EL display element 3 with an adhesive layer 14 interposed therebetween, and the adhesive layer 14 is It is laminated on the retardation film 20.

    [Example]    

(1) Method for measuring film thickness

The measurement was performed using a digital micrometer MH-15 manufactured by Nikon Corporation.

(2) Method for measuring phase difference

The measurement was performed using a phase difference measuring device KOBRA-WPR (manufactured by Oji Measurement Co., Ltd.).

[Production of retardation film 1]

5 parts (weight-average molecular weight: 30,000) of photo-alignment material having the following structure and 95 parts of cyclopentanone (solvent) were mixed, and the obtained mixture was stirred at 80 ° C. for 1 hour to obtain a composition for forming an alignment film. .

To 100 parts of a mixture of the polymerizable liquid crystal compound A and the polymerizable liquid crystal compound B shown below at a mass ratio of 90:10, 1.0 part of a leveling agent (F-556; manufactured by DIC Corporation) and polymerization initiation were added. 6 parts of 2-dimethylamino-2-benzyl-1- (4-morpholinylphenyl) butan-1-one (`` Irgacure369 (i.e., Irg369) '', manufactured by BASF Japan) .

Furthermore, 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 composition for forming a liquid crystal cured film.

The polymerizable liquid crystal compound A is produced by a method described in Japanese Patent Application Laid-Open No. 2010-31223. The polymerizable liquid crystal compound B is produced by a method described in Japanese Patent Application Laid-Open No. 2009-173893. The respective molecular structures are shown below.

(Polymerizable Liquid Crystal Compound A)

(Polymerizable Liquid Crystal Compound B)

[Manufacturing of a laminated body composed of a substrate, an alignment film, and a layer cured by a polymerizable liquid crystal compound]

A 50 μm-thick cycloolefin-based resin film [trade name “ZF-14-50” manufactured by Japan Zeon Corporation] was subjected to a corona treatment. The corona-treated surface was coated with a composition for forming an alignment film with a bar coater. The coating film was dried at 80 ° C for 1 minute. The polarized UV was irradiated on the dried coating film using a polarized UV irradiation device [trade name "SPOT CURE SP-9" manufactured by USHIO Electric Co., Ltd.] so that the axis angle was 45 ° to obtain an alignment film. The irradiation of polarized UV was performed so that the cumulative light amount at a wavelength of 313 nm was 100 mJ / cm ² .

Next, on the alignment film, a composition for forming a liquid crystal cured film was applied using a bar coater. The coating film was dried at 120 ° C for 1 minute. The dried coating film was irradiated with ultraviolet rays using a high-pressure mercury lamp [trade name: "UNICURE VB-15201BY-A" manufactured by USHIO Electric Co., Ltd.]. The ultraviolet irradiation step is performed under a nitrogen environment so that the cumulative light amount at a wavelength of 365 nm becomes 250 mJ / cm ² . Immediately after the irradiation, the cured film was put into an oven set at 5 ° C for 20 seconds as a cooling step. Immediately after taking out from the oven, the ultraviolet step and the cooling step were performed again to obtain a laminated body composed of a substrate, an alignment film, and a layer hardened by a polymerizable liquid crystal compound.

(Measurement of phase difference value)

An adhesive layer is laminated | stacked on the layer which hardened the polymerizable liquid crystal compound of a laminated body. The laminated body is bonded to glass via this adhesive layer. Then, the base material provided in the laminated body was peeled to obtain a sample for evaluating a phase difference value. As a result, the retardation value Re (λ) of the layer hardened by the polymerizable liquid crystal compound has Re (450) = 121 nm, Re (550) = 142 nm, and Re (650) = 146 nm. As a result, Re (450) / Re (550) = 0.85 and Re (650) / Re (550) = 1.03 were calculated. The layer hardened by the polymerizable liquid crystal compound is a layer giving a retardation of λ / 4.

(Measurement of puncture elastic modulus)

、0.5R者。針的穿刺速度為0.33cm/秒。相位差膜1的穿刺彈性模數係表示於表1。 The measurement of the puncture elastic modulus was performed as follows. The needle was installed in a portable compression tester "KES-G5 Needle Penetration Measurement Specification" manufactured by KATO TECH Co., Ltd. The main surface of the laminated body with the peeled base material fixed between two plates having circular openings with a diameter of 11 mm was pierced vertically with a needle to calculate the force (gf) before the break Strain (mm). This operation was performed on five retardation films (samples for puncture test), and the average value was used as the puncture elastic modulus of the retardation film. Needle system uses a tip diameter of 1mm

, 0.5R. The puncture speed of the needle was 0.33 cm / sec. The puncture elastic modulus of the retardation film 1 is shown in Table 1.

[Production of retardation film 2]

Regarding the ultraviolet rays irradiated when the coating film of the composition for forming a liquid crystal cured film is cured, the cumulative amount of light per time is set to 400 mJ / cm ² at a wavelength of 365 nm (that is, the total accumulation of two ultraviolet rays) Except for the amount of light being 800 mJ / cm ² ), a laminated body including the retardation film 2 was produced in the same manner as in [Production of the retardation film 1]. The puncture elastic modulus of the retardation film 2 was measured in the same manner as described above. The puncture elastic modulus of the retardation film 2 is shown in Table 1.

[Production of retardation film 3]

Regarding the ultraviolet rays irradiated when the coating film of the composition for forming a liquid crystal cured film is cured, the cumulative amount of light per time is set to 600 mJ / cm ² at a wavelength of 365 nm (that is, the total accumulation of two ultraviolet irradiations). Except that the amount of light was 1200 mJ / cm ² ), a laminated body including the retardation film 3 was produced in the same manner as in [Production of the retardation film 1]. The puncture elastic modulus of the retardation film 3 was measured in the same manner as described above. The puncture elastic modulus of the retardation film 3 is shown in Table 1.

[Production of retardation film 4]

Regarding the ultraviolet rays irradiated when the coating film of the composition for forming a liquid crystal cured film is hardened, the cumulative light quantity per time is set to 800 mJ / cm ² at a wavelength of 365 nm (that is, the total accumulation of two ultraviolet irradiations) Except that the amount of light was 1600 mJ / cm ² ), a laminated body including the retardation film 4 was produced in the same manner as in [Production of the retardation film 1]. The puncture elastic modulus of the retardation film 4 was measured in the same manner as described above. The puncture elastic modulus of the retardation film 4 is shown in Table 1.

[Production of retardation film 5]

For the composition for forming a vertical alignment film, 5 parts by weight of a commercially available alignment polymer SUNEVER SE-610 (manufactured by Nissan Chemical Industries, Ltd.) and 95 parts by weight of methyl ethyl ketone (solvent) were mixed. To obtain a composition for forming a vertical alignment film.

The composition for forming a vertical alignment retardation layer is made of 20 parts by weight of a photopolymerizable nematic liquid crystal compound (RMM28B manufactured by MERCK) and Irgacure 907 (made by BASF, Irg-907) 1 as a photopolymerization initiator. 1 A part by weight was dissolved in 80 parts by weight of propylene glycol monomethyl ether acetate to prepare a coating liquid for forming a vertical alignment retardation layer.

A 50 μm-thick cycloolefin-based resin film [trade name “ZF-14-50” manufactured by Japan Zeon Corporation] was subjected to a corona treatment. The corona-treated surface was coated with a composition for forming a vertical alignment film by a bar coater. The coating film was heated at 100 ° C. for 120 seconds to harden it to form a vertical alignment film.

On the previously obtained vertical alignment film, a coating liquid for forming a vertical alignment retardation layer was applied, and the coating film was heated at 80 ° C. for 60 seconds. Then, ultraviolet ray (UVB) was irradiated to a cumulative light amount of 220 mJ / cm ² , and the composition for forming a vertical alignment retardation layer was polymerized and cured to form a vertical alignment retardation layer having a thickness of 0.7 μm on the vertical alignment film. When the retardation value of the obtained vertical alignment retardation layer at a wavelength of 550 nm was measured, Re (550) = 1 nm and Rth (550) =-75 nm. That is, the vertical alignment phase difference layer is a positive C layer satisfying the relationship of nx ≒ ny <nz. In addition, the phase difference value of the cycloolefin-based resin film as a base material at a wavelength of 550 nm is approximately zero, and the optical characteristics of the vertical alignment retardation layer are not affected.

Next, on the obtained vertical alignment retardation layer, a layer giving a retardation of λ / 4 was formed in the same manner as in [Production of the retardation film 2], and a multilayer body including the retardation film 5 was produced. In this manner, a laminated body including a sequentially laminated base material, a vertical alignment film, a positive C layer, an alignment film, a layer giving a retardation of λ / 4, and a retardation film 5 was produced. The puncture elastic modulus of the retardation film 5 was measured in the same manner as described above. The puncture elastic modulus of the retardation film 5 is shown in Table 1.

[Preparation of the adhesive layer]

Adhesive A: 5 μm thick sheet adhesive ("NCF # L2" manufactured by Lintec Corporation)

Adhesive B: 25 μm-thick sheet adhesive ("P-3132" manufactured by Lintec Corporation)

[Preparation of protective film]

Protective film A: A film of a hard coat layer having a thickness of 3 μm is formed on a 25 μm-thick stretch film made of norbornene-based resin [trade name “COP25ST-HC” manufactured by Nippon Paper Co., Ltd.]

Protective film B: Triethyl cellulose film with a thickness of 20 μm [trade name "ZRG20SL" manufactured by FUJIFILM Co., Ltd.]

Protective film C: unstretched film made of triethylfluorene cellulose with a thickness of 25 μm

[Making of front panel]

A front panel having hard coat layers on both sides of the base film is prepared. The base film was a polyimide film having a thickness of 50 μm, and the thickness of the hard coat layer was 10 μm.

[Example 1]

[Production of polarizing plate]

A polyvinyl alcohol film (average degree of polymerization of about 2400, saponification degree of 99.9 mol% or more) with a thickness of 20 μm was stretched to about 4 times in one axis by dry stretching. Furthermore, it was immersed in pure water at 40 ° C under tension. After 40 seconds, the dye solution was immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.052 / 5.7 / 100 at 28 ° C. for 30 seconds. Next, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 11.0 / 6.2 / 100 at 70 ° C. for 120 seconds. Then, it was washed with pure water at 8 ° C. for 15 seconds, and was dried at 60 ° C. for 50 seconds and then at 75 ° C. for 20 seconds while maintaining a tension of 300 N. Then, iodine was adsorbed and aligned on the polyvinyl alcohol film. A polarizer with a thickness of 7 μm.

A water-based adhesive is applied to one surface of the polarizer, and the protective film A is bonded. At this time, it adhere | attached so that the extending direction of the protective film A might be 45 degrees with respect to the absorption axis of a polarizer. A water-based adhesive is applied to the other surface of the polarizer, and the protective film B is bonded. Then, it was dried to obtain a polarizing plate. The above-mentioned water-based adhesive is prepared by dissolving 3 parts of carboxyl-modified polyvinyl alcohol [trade name "KL-318" obtained from KURARAY Co., Ltd.] with 100 parts of water, and adding a water-soluble ring 1.5 parts of an epoxy resin-based polyamine epoxy-based additive [trade name "SUMIREZ RESIN 650 (30)", a 30% solids solution by Taoka Chemical Industry Co., Ltd.].

An adhesive A is laminated on a layer made of a polymerizable liquid crystal compound in the multilayer body produced in [Production of the retardation film 2]. Then, the base material was peeled from the laminated body, and the adhesive B was layered on the area exposed by the peeling. In this way, a retardation film 2 with an adhesive on both sides is produced, which is composed of an adhesive A, a layer cured by a polymerizable liquid crystal compound, an alignment film, and an adhesive B.

[Production of circular polarizer]

On the protective film B of the polarizing plate, the adhesive A of the retardation film 2 with an adhesive is attached on both sides, and the retardation film 2 with the adhesive on both sides is attached. The slow axis of the layer hardened by the polymerizable liquid crystal compound is 45 degrees with respect to the absorption axis of the polarizer, and 90 degrees with respect to the extending direction of the protective film A. In this way, a circular polarizing plate was produced, which was made of a protective film A, an aqueous adhesive layer, a polarizer, an aqueous adhesive layer, a protective film B, an adhesive A, a layer made of a polymerizable liquid crystal compound, and an alignment film. And adhesive B.

The circular polarizing plate was cut into a rectangle having a size of 140 mm × 70 mm so that the slow axis and the long side of the layer hardened by the polymerizable liquid crystal compound were parallel to each other. At this time, the extending direction of the protective film A is parallel to the short-side direction. The cut circular polarizing plate is adhered to a glass plate having a thickness of 0.4 mm with adhesive B interposed therebetween (manufactured by Corning Corporation, model: EAGLE XG (registered trademark)). In this manner, a sample for evaluation was prepared.

[Example 2]

In Example 1, the same procedure as in Example 1 was performed except that the multilayer body produced in [Production of Phase Difference Film 3] was used instead of the multilayer body produced in [Production of Phase Difference Film 2], and circles were produced. A polarizing plate and a sample for evaluation were prepared.

[Example 3]

In Example 1, the same procedure as in Example 1 was performed except that the multilayer body produced in [Production of Phase Difference Film 4] was used instead of the multilayer body produced in [Production of Phase Difference Film 2], and circles were produced. A polarizing plate and a sample for evaluation were prepared.

[Example 4]

In Example 2, the protection was attached in such a manner that the slow axis of the layer hardened by the polymerizable liquid crystal compound was 45 degrees with respect to the absorption axis of the polarizer and 0 degree with respect to the extension direction of the protective film A. Except for the film A and the polarizer, the same operation as in Example 2 was performed to produce a circular polarizing plate, and an evaluation sample was produced. At this time, the extending direction of the protective film A is parallel to the longitudinal direction.

[Example 5]

In Example 1, the same procedure as in Example 1 was performed except that the multilayer body produced in [Production of Phase Difference Film 5] was used instead of the multilayer body produced in [Production of Phase Difference Film 2] to produce a circle. A polarizing plate and a sample for evaluation were prepared.

[Example 6]

A circularly polarizing plate was produced in the same manner as in Example 1 except that the protective film B was not laminated during the production of the polarizing plate. Furthermore, the adhesive layer B is laminated on the protective film A. The front panel and the circular polarizing plate are bonded together via the adhesive layer B. In this way, a circular polarizing plate is produced, which is a front panel, an adhesive layer B, a protective film A, an aqueous adhesive layer, a polarizer, an adhesive A, a layer hardened by a polymerizable liquid crystal compound, an alignment film, and an adhesive. B is composed. In addition, it carried out similarly to Example 1, and produced the sample for evaluation.

[Example 7]

[Composition for forming surface treatment layer]

The following components were mixed to prepare a composition for forming a surface treatment layer.

2.0 parts by mass of dendritic polymer acrylate (Miramer SP1106, Miwon) with 18-functional acrylofluorenyl group, 10.0 parts by mass of amine ester acrylate (Miramer PU-620D, Miwon) with 6-functional acryl group, 8.0 parts by mass of acrylate monomer (M340, Miwon) with trifunctional acrylofluorenyl group, 2 parts by mass of photopolymerization initiator (Irgacure-184, BASF), leveling agent (BYK-3530, BYK) 0.1 Mass part, 77.9 mass parts of methyl ethyl ketone (MEK).

[Composition for forming polarizer]

(Polymerizable Liquid Crystal Compound)

The polymerizable liquid crystal compound is a polymerizable liquid crystal compound represented by formula (1-6) [hereinafter also referred to as compound (1-6)] and a polymerizable liquid crystal compound represented by formula (1-7) [hereinafter also referred to as compound (1-7)].

Compound (1-6) and compound (1-7) were synthesized by the method described in Lub et al. Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996).

(Dichroic pigment)

The dichroic pigment is an azo pigment described in Examples of Japanese Patent Application Laid-Open No. 2013-101328 represented by the following formulae (2-1a), (2-1b), and (2-3a).

The composition for forming a polarizing layer is composed of 75 parts of compound (1-6) and 25 parts of compound (1-7) as the dichroic dyes of the above formulae (2-1a), (2-1b), (2- 2.5 parts each of the azo dye represented by 3a), 2-dimethylamino-2-benzyl-1- (4-morpholinylphenyl) but-1-one (Irgacure 369, 6 parts by weight of BASF, Japan) and 1.2 parts of polyacrylate compound (BYK-361N, manufactured by BYK-Chemie) as a leveling agent were mixed in 400 parts of toluene in a solvent, and the resulting mixture was stirred at 80 ° C Modulate it in 1 hour.

The composition for forming a surface treatment layer is applied to the protective film A. The coating film was dried at 80 ° C. for 5 minutes, and then a UV irradiation device was used to irradiate ultraviolet rays so that the exposure amount was 500 mJ / cm ² (365 nm standard) to harden the coating film. As the UV irradiation device, SOPT CURE SP-7 manufactured by USHIO Electric Co., Ltd. was used. The thickness of the surface treatment layer was 10.0 μm.

On the surface treatment layer of the protective film A, a composition for forming an alignment film used for producing the retardation film 1 was applied by a bar coating method. The coating film was dried at 80 ° C for 1 minute. Then, the coating film was irradiated with polarized UV using the above-mentioned UV irradiation device and the wire grid to give an alignment function to the coating film. The exposure amount was 100 mJ / cm ² (365 nm standard). The wire grid system uses UIS-27132 # # (made by USHIO Electric Co., Ltd.). In this way, an alignment film is formed. The alignment film has a thickness of 100 nm.

The composition for forming a polarizer is applied on the formed alignment film by a bar coating method. The coating film was dried by heating at 100 ° C for 2 minutes, and then cooled to room temperature. Using the above-mentioned UV irradiation device, the coating film was irradiated with ultraviolet rays so that the accumulated light amount became 1200 mJ / cm ² (365 nm standard) to form a polarizer. The thickness of the obtained polarizer was 3 μm. A composition containing polyvinyl alcohol and water was applied to the polarizer so that the thickness after drying was 0.5 μm, and dried at 80 ° C. for 3 minutes to form a protective layer. In this way, a polarizing plate is produced, which is composed of a protective film A, a surface treatment layer, an alignment film, a polarizer, and a protective layer.

A circularly polarizing plate was produced in the same manner as in Example 6 except that the above-mentioned polarizing plate was used, and a sample for evaluation was produced. The evaluation samples are sequentially provided: a front panel, an adhesive layer B, a protective film A, a surface treatment layer, an alignment film, a polarizer, a protective layer, an adhesive A, a layer hardened by a polymerizable liquid crystal compound, and an alignment film. And adhesive B.

[Example 8]

A circular polarizing plate was produced in the same manner as in Example 7 except that the protective film C was used instead of the laminated body of the protective film A and the surface treatment layer, and a sample for evaluation was produced. The samples for evaluation are sequentially provided: a front panel, an adhesive layer B, a protective film C, an alignment film, a polarizer, a protective layer, an adhesive A, a layer hardened by a polymerizable liquid crystal compound, an alignment film, and an adhesive B.

[Example 9]

A circular polarizing plate was produced in the same manner as in Example 8 except that the front panel was not laminated, and a sample for evaluation was produced. The evaluation sample is sequentially provided with a protective film C, an alignment film, a polarizer, a protective layer, an adhesive A, a layer cured by a polymerizable liquid crystal compound, an alignment film, and an adhesive B.

[Comparative Example 1]

In Example 1, the same procedure as in Example 1 was performed except that the multilayer body produced in [Production of Phase Difference Film 1] was used instead of the multilayer body produced in [Production of Phase Difference Film 2], and a circle was produced. A polarizing plate and a sample for evaluation were prepared.

[Evaluation of hue before and after heat resistance test]

For the reflector, MIRO (5011GP) manufactured by ALANOD was prepared. This reflecting plate is a specular reflecting plate having a reflecting surface formed by vapor deposition.

The evaluation sample was placed on the reflection plate. The color tone (a *, b *) of the reflected light was measured using a spectrophotometer (trade name: CM-2600d, manufactured by Konica Minolta Japan Co., Ltd.). The color tone of the reflected light is a value when the light source is D65, and is measured by the SCI method (including regular reflected light).

Specifically, point 5 shown in FIG. 3 is used as a measurement point. The nine points 5 shown in FIG. 3 are points in a region of 5 mm from the end of the circular polarizer to the inside, and the positions are about 30 mm in the short side direction and about 65 mm in the long side direction.

For the evaluation samples prepared in Examples 1 to 9 and Comparative Example 1, the hue of the reflected light was measured before and after storage in a dryer at a temperature of 80 ° C for 168 hours. The absolute value of the hue change Δa * b * at each point was calculated. According to the direction of the hue change, the hue change value of each point is calculated, and the difference between the maximum value and the minimum value of the hue change value of each evaluation sample is Δa * b * (MAX-MIN). The results are shown in Tables 2 and 3.

△ a = a * (after heat resistance test) -a * (before heat resistance test)

△ b = b * (after heat resistance test) -b * (before heat resistance test)

△ a * b * = [(△ a *) ² + (△ b *) ² ] ^1/2

The hue change value is Δa * b * when Δa * is 0 or more, and Δa * b * × -1 when Δa * is less than 0.

    [Industrial availability]    

According to the present invention, it is possible to provide a circularly polarizing plate provided with a retardation film, which is a circularly polarizing plate with little change in the hue of reflected light before and after being placed in a high-temperature environment.

Claims (7)

A circular polarizing plate having a polarizing plate and a retardation film, wherein the retardation film includes a retardation layer; the puncture elastic modulus of the retardation film is 15 gf / mm or more; and the puncture elastic modulus is by using a tip 1mm diameter

Modulus of elasticity measured with a 0.5 R needle and a test at a puncture speed of 0.33 cm / sec.     The circular polarizing plate according to item 1 of the scope of patent application, wherein the circular polarizing plate has an adhesive layer on its surface; the polarizing plate has a polarizer; and the retardation layer includes a polymerized liquid crystal compound hardened. The phase difference film is disposed between the polarizing plate and the adhesive layer.         The circular polarizing plate according to item 2 of the scope of patent application, wherein the polarizer is formed of a layer hardened by a liquid crystal compound.         The circular polarizing plate according to item 2 or 3 of the scope of application for a patent, wherein the shape of the circular polarizing plate is substantially rectangular; in the polarizing plate, the polarizer is opposite to the retardation film side The area layer has a protective film; the protective film is an extended film; the extending direction of the protective film is substantially parallel to the short-side direction of the circular polarizing plate.         The circular polarizing plate according to any one of claims 1 to 4, wherein the retardation film includes two retardation layers.         A circular polarizing plate with a front panel is obtained by laminating the circular polarizing plate according to any one of items 1 to 5 of the patent application scope and the front panel with a laminated layer therebetween.         A display device is a display device in which a circular polarizing plate as described in any one of the second to fourth items of the patent application scope is laminated through the aforementioned adhesive.