TW202234099A - Circular polarizing plate, optical laminate and image display device - Google Patents

Abstract

The present invention provides a circular polarizing plate having a novel configuration, and optical laminate and image display device including the same.

The present invention provides a circular polarizing plate, and optical laminate and image display device including the same; the circular polarizing plate includes a linear polarizing plate and a liquid crystal curing layer, wherein the linear polarizing plate includes a polarizer and a protective film laminated only on one side of the polarizer, and the polarizer, the protective film, and the liquid crystal curing layer are arranged in this order.

Description

Circular polarizing plate, optical laminate, and image display device

The present invention relates to a circularly polarizing plate, an optical laminate, and an image display device.

Regarding display devices represented by organic electroluminescence (EL) display devices, for example, flexible displays in which the display device can be bent using a material having flexibility are known. In an organic EL display device, it is known to use a circularly polarizing plate or the like to improve antireflection performance in order to suppress deterioration of visibility due to reflection of external light [eg, Japanese Patent Laid-Open No. 2020-134934 (Patent Document 1)]. A circularly polarizing plate can be obtained by laminating a linear polarizing plate and a retardation layer, and a cured product layer of a polymerizable liquid crystal compound may be used as a retardation layer.

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2020-134934

An object of the present invention is to provide a circularly polarizing plate having a novel structure, and an optical laminate and an image display device including the circularly polarizing plate.

The present invention provides the following circularly polarizing plate, optical laminate, and image display device.

[1] A circular polarizer, comprising: a linear polarizer and a liquid crystal hardening layer;

The linear polarizer includes a polarizer and a protective film laminated only on one side of the polarizer; and the polarizer, the protective film, and the liquid crystal cured layer are sequentially arranged.

[2] The circularly polarizing plate according to [1], further comprising a hard coat layer between the protective film and the liquid crystal cured layer.

[3] The circularly polarizing plate according to [1] or [2], wherein the polarizer has a boron content of 0.5 mass % or more and 5.5 mass % or less.

[4] The circularly polarizing plate according to any one of [1] to [3], wherein the protective film is a cyclic polyolefin-based resin film.

[5] The circularly polarizing plate according to any one of [1] to [4], wherein the liquid crystal cured layer includes a first liquid crystal cured layer and a second liquid crystal cured layer, and the polarizer and the protective film , the said 1st liquid crystal hardening layer and the said 2nd liquid crystal hardening layer are arrange|positioned sequentially.

[6] The circularly polarizing plate according to any one of [1] to [5], wherein any one of the layers other than the aforementioned polarizer has light selective absorptivity.

[7] The circularly polarizing plate according to any one of [1] to [6], comprising, in this order, the polarizer, the protective film, the liquid crystal cured layer, and an adhesive layer.

[8] An optical laminate for a flexible image display device, comprising: the circularly polarizing plate according to any one of [1] to [7], and a front panel or a touch sensor panel.

[9] An image display device comprising: the circularly polarizing plate according to any one of [1] to [7], or the optical laminate according to [8].

The present invention provides a circular polarizing plate with a novel structure, an optical laminate and an image display device including the circular polarizing plate.

1,2,3: Circular polarizer

4,5: Optical Laminate

10,11: Linear polarizer

20: Retardation layer structure

30a: 1st bonding layer

30b: 2nd bonding layer

30c: 3rd bonding layer

30d: 4th bonding layer (4th adhesive layer)

40: Image Display Components

50: Front panel

101: Polarizer

102: Protective film

103: Hard Coating

201: The first liquid crystal cured layer

202: Second liquid crystal cured layer

203: Separation Membrane

FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of the circularly polarizing plate of the present invention.

FIG. 2 is a schematic cross-sectional view showing another example of the layer structure of the circularly polarizing plate of the present invention.

3 is a schematic cross-sectional view showing another example of the layer structure of the circular polarizing plate of the present invention.

FIG. 4 is a schematic cross-sectional view showing an example of the layer structure of the optical laminate of the present invention.

5 is a schematic cross-sectional view showing another example of the layer structure of the optical laminate of the present invention.

FIG. 6 is an explanatory diagram illustrating a micro-Raman spectroscopic analysis of the polarizing plate of the present invention.

Hereinafter, the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. All the drawings below are shown to facilitate understanding of the present invention, and the size or shape of each component shown in the drawings does not necessarily correspond to the size or shape of the actual component.

<Circular polarizer>

(1) The composition of the circular polarizer

FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of a circular polarizing plate (hereinafter also simply referred to as a “circular polarizing plate”) of the present invention. The circular polarizing plate 1 shown in FIG. 1 includes a linear polarizing plate 10 and a retardation layer structure 20 which is a structure including a retardation layer. In the circular polarizing plate 1, the linear polarizing plate 10 and the retardation layer structure 20 are bonded to each other via the first bonding layer 30a. The retardation layer is a liquid crystal cured layer (a cured product layer obtained by polymerizing and curing a polymerizable liquid crystal compound). The term "circular polarizer" includes elliptically polarizers.

In addition, the circular polarizing plate suitable for the flexible image display device is preferably one that can be bent. The so-called "bendable" means that the layer constituting the circular polarizing plate is not cracked and can be bent. Such a circularly polarizing plate is required to be a thinner film for good bending resistance (flexibility). Therefore, the linear polarizer included in the circular polarizer is effective only by having a protective film on one side of the polarizer (so-called "single protective polarizer").

FIG. 2 is a schematic cross-sectional view showing another example of the layer structure of the circular polarizer, and shows a specific example of the layer structure of the linear polarizer 10 and the retardation layer structure 20 . In the circular polarizing plate 2 shown in FIG. 2, the linear polarizing plate 10 and the retardation layer structure 20 are also bonded to each other via the first bonding layer 30a. As shown in FIG. 2 , the linear polarizer 10 is a single-protection polarizer including a “polarizer (linear polarizer) 101 ” and a “protective film 102 laminated only on one side of the polarizer 101 ”. The protective film 102 is laminated on the surface of the polarizer 101 on the retardation layer structure 20 side. Although not shown, the protective film 102 is bonded to the polarizer 101 via an adhesive layer. In the circular polarizer 2 , the outermost surface on the side of the linear polarizer 10 is the surface of the polarizer 101 .

In the circular polarizer 2 , the polarizer 101 , the protective film 102 and the retardation layer structure 20 are arranged in sequence, that is, the polarizer 101 , the protective film 102 and the liquid crystal curing layer belonging to the retardation layer are arranged in sequence. In the circularly polarizing plate 2, the retardation layer structure 20 is equipped with the 1st liquid crystal cured layer 201, the 2nd bonding layer 30b, and the 2nd liquid crystal cured layer 202 in this order from the linear polarizer 10 side. In order to bond the circularly polarizing plate 2 to a display panel, for example, the 2nd liquid crystal cured layer 202 may be provided with the 3rd bonding layer 30c and the separation film 203 on the opposite side to the 2nd bonding layer 30b side.

The layer structure of the circular polarizer is not limited to the structure shown in FIG. 2 . E.g,

a) The circularly polarizing plate system may not have either the first liquid crystal cured layer 201 or the second liquid crystal cured layer 202, and the retardation layer structure 20 should just have at least one liquid crystal cured layer (retardation layer).

b) It may contain more than one alignment layer.

c) It is not necessary to have the second bonding layer 30b.

d) A hard-coat layer can be arrange|positioned between the protective film 102 and the 1st liquid crystal cured layer 201 (retardation layer structure 20).

FIG. 3 is a schematic cross-sectional view showing still another example of the layer structure of the circular polarizer, and shows a specific example of the layer structure of the linear polarizer 11 and the retardation layer structure 20 . In the circularly polarizing plate 3 shown in FIG. 3, the linear polarizing plate 11 and the retardation layer structure 20 are mutually bonded via the 1st bonding layer 30a. The circular polarizer 3 shown in FIG. 3 has a configuration corresponding to the above d), and the linear polarizer 11 includes a polarizer (linear polarizer) 101 , a protective film 102 laminated only on one side of the polarizer 101 , and a laminated Hard coat layer 103 on the surface of the protective film 102 on the side of the retardation layer structure 20 . The protective film 102 is laminated on the surface of the polarizer 101 on the side of the retardation layer structure 20 . Although not shown, the protective film 102 is bonded to the polarizer 101 via an adhesive layer. In the circular polarizer 3 , the outermost surface on the side of the linear polarizer 11 is also the surface of the polarizer 101 . Moreover, similarly to the circular polarizing plate 2 shown in FIG. 2, the circular polarizing plate 3 shown in FIG. 3 also has the case where the 3rd bonding layer 30c and the separation film 203 are provided.

When the circular polarizers 1 , 2 , and 3 are applied to an image display device such as an organic EL image display device, the circular polarizers 1 , 2 , and 3 are arranged so that the side of the linear polarizers 10 , 11 is the recognition side. At this time, as described above, in order to bond the circularly polarizing plates 1, 2, and 3 to the image display element, the third bonding layer 30c (the separation film 203 is peeled off/removed) can be used. That is, the circular polarizing plates 1, 2, and 3 are applied to the organic EL image display device, etc. In the case of an image display device, the circularly polarizing plates 1, 2, and 3 are arranged so that the side of the retardation layer structure 20 is the side of the image display element.

The circularly polarizing plate system of the present invention is advantageous in terms of the following features.

A) The adhesion between the protective film 102 of the linear polarizer 10 and the first bonding layer 30a, or the adhesion between the hard coat layer 103 of the linear polarizing plate 11 and the first bonding layer 30a is high, resulting in a circular polarizer The durability is high. In particular, in the circular polarizing plate 3 shown in FIG. 3, in the configuration in which the hard coat layer 103 and the first bonding layer 30a are in contact with each other, even if corona treatment is not applied to their bonding surfaces, or even if corona treatment is performed With low strength, good adhesion between these layers can also be obtained.

If the corona treatment is performed for a long period of time, crystalline foreign matter (oxalic acid, etc.) will adhere to the corona-treated object, and there will be a problem that the yield will decrease. Moreover, it is known that ozone and nitrogen oxides (NOx) are generated due to corona discharge. . By omitting the corona treatment or reducing the intensity of the corona treatment, the above problems can be solved or reduced.

B) When the polarizer 101 is a polyvinyl alcohol-based resin film with iodine adsorbed and oriented, if the protective film 102 exists between the polarizer 101 and the image display element, and further the hard coat layer 103 exists, thereby, Even if the circular polarizing plate of the present invention is kept in a humid and hot environment, for example, the migration of iodine from the polarizer 101 to the image display element can be suppressed or prevented. Therefore, the deterioration of the retardation layer structure 20 can be suppressed or prevented, or when an input device such as a touch sensing panel is attached to the circularly polarizing plate of the present invention, the deterioration of the touch sensing panel or the like can be suppressed or prevented. .

Hereinafter, the elements constituting or constituting the circular polarizing plate will be described in detail.

(2) Linear polarizer

The linear polarizer includes a polarizer (linear polarizer) 101 and a protective film 102 laminated only on one side of the polarizer 101 . The term "one side of the polarizer 101" refers to the retardation layer structure on the polarizer 101 20 side faces. The linear polarizer preferably includes a polarizer 101 , a protective film 102 laminated on only one side of the polarizer 101 , and a hard coat layer 103 laminated on the surface of the retardation layer structure 20 side of the protective film 102 .

(2-1) Polarizer

The polarizer 101 is an optical film having the property of "permeating linearly polarized light having a vibration plane orthogonal to the absorption axis when unpolarized light is incident." The polarizer 101 is preferably a polyvinyl alcohol-based resin film (hereinafter also referred to as "PVA-based film") in which iodine is adsorbed and oriented. Hereinafter, the PVA-based film in which iodine is adsorbed and directed, which is a preferable polarizer 101, will be described.

The polarizer 101 includes, for example, a PVA-based film such as a polyvinyl alcohol film, a partially formaldehyde-based polyvinyl alcohol film, and an ethylene/vinyl acetate copolymer-based partially saponified film, which is dyed with iodine and uniaxially stretched. processor etc. Preferably, the PVA-based film having the iodine adsorbed and oriented by dyeing is treated with a boric acid aqueous solution, and thereafter, a washing step of rinsing off the boric acid aqueous solution is performed. A known method can be adopted for each step.

A polyvinyl alcohol-based resin (hereinafter also referred to as "PVA-based resin") can be produced by saponifying a polyvinyl acetate-based resin. As far as polyvinyl acetate resins are concerned, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, it can also be composed of vinyl acetate and other monomers that can be copolymerized with vinyl acetate. the copolymer. Examples of other monomer systems that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, (meth)acrylamides having an ammonium group, and the like.

In addition, in this specification, "(meth)acrylic acid" means that either acrylic acid or methacrylic acid may be used. "(meth)" in (meth)acrylate etc. also has the same meaning.

The saponification degree of PVA resin is usually about 85 to 100 mol %, preferably 98 mol % or more. PVA-based resins can be modified, for example, aldehyde-modified polyvinyl formaldehyde or polyvinyl formaldehyde can also be used. Vinyl acetal, etc. The average degree of polymerization of the PVA-based resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000. The average degree of polymerization of the PVA-based resin can be obtained in accordance with JIS K 6726 (1994). When the average degree of polymerization is less than 1,000, it is difficult to obtain favorable polarization performance, and when it exceeds 10,000, the film workability may be deteriorated.

The circular polarizing plate of the present invention is particularly suitable for flexible image display devices. Regarding the circular polarizing plate used in the flexible image display device, the thickness of each component constituting the circular polarizing plate is preferably thinner. The thickness of the polarizer 101 is usually 30 μm or less, preferably 15 μm or less, more preferably 13 μm or less, and still more preferably 10 μm or less. The thickness of the polarizer 101 is usually 2 μm or more, preferably 3 μm or more, for example, 5 μm or more.

In order to obtain the polarizer 101 with a better thickness, it can be listed as “using a PVA film (thin film PVA film) with a thickness of about 15 to 40 μm as a starting material, and performing dyeing treatment and uniaxial stretching on the thin film PVA film. process to obtain the polarizer 101". The thickness of the obtained polarizer 101 can be made thin by using the PVA-type film of a thin film in advance (1st manufacturing method).

With regard to the preferred thin-film PVA-based film as a starting material, an extremely thin thin-film PVA-based film can be realized by forming a resin layer composed of a PVA-based resin on an appropriate base film (Second Production Method ). In this case, the production method of the thin-film PVA film may include "preparing a base film, coating a solution of a resin such as PVA-based resin (PVA-based resin solution, etc.) on the base film, and drying to remove the solvent, etc., step of forming a resin layer on it. A primer layer may be formed in advance on the surface of the base film on which the resin layer is to be formed. As the base film, a film using a thermoplastic resin can be used, and this thermoplastic resin can be used for the protective film 102 described later.

The thin-film PVA-based film that is the starting material in the first manufacturing method or the second manufacturing method can be induced into the polarizer 101 by performing dyeing treatment and uniaxial stretching treatment as described above. In the second manufacturing method, the PVA-based resin solution is applied on the base film, and then the resin layer is adjusted as necessary. After that, the base film and the resin layer are uniaxially stretched, and then the resin layer is dyed with iodine, and the iodine is adsorbed and oriented in the resin layer.

The PVA film after dyeing treatment (orientation of iodine adsorption) and uniaxial stretching treatment is preferably followed by cross-linking treatment with boric acid. In the first production method, for example, after the thin-film PVA film is subjected to dyeing treatment and uniaxial stretching treatment, the film may be brought into contact with a boric acid-containing solution (boric acid-containing solution). A cleaning treatment may also be performed to rinse off the boric acid-containing solution adhering to the surface of the film after the cross-linking treatment.

The polarizer 101 obtained by the second manufacturing method is also the same as the first manufacturing method. That is, the base film of the resin layer after the dyeing treatment and the uniaxial stretching treatment can be carried out, for example, by contacting the solution containing boric acid in its original state (without peeling the base film). Crosslinking treatment. The base film of the resin layer after the cross-linking treatment can be cleaned according to need.

The boric acid-containing solution used to cross-link the iodine-adsorbed PVA-based film or resin layer is preferably a boric acid-containing aqueous solution, and the amount of boric acid in the boric acid-containing aqueous solution is usually per 100 parts by mass Water is about 2 to 15 parts by mass, preferably 5 to 12 parts by mass. The boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by mass, preferably about 5 to 12 parts by mass per 100 parts by mass of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50°C or higher, preferably 50 to 85°C, more preferably 60 to 80°C.

The uniaxial stretching of the PVA film, the base film, and the resin layer can be performed before dyeing, during dyeing, or in boric acid treatment after dyeing, or in multiple stages. Uniaxial extension. The total elongation ratio is usually 3 times or more, preferably 3.5 times or more, and more preferably 4 times times more. The upper limit of the elongation ratio is not particularly limited, but from the viewpoint of suppressing cracks and the like, it is preferably 8 times or less, and more preferably 6 times or less.

The boron content of the polarizer 101 is preferably 0.5 mass % or more, more preferably 1.5 mass % or more, still more preferably 2.5 mass % or more, and may be 3.5 mass % or more. By making the boron content 0.5 mass % or more, iodine can be stably held, and the effect of suppressing the decrease in the degree of polarization of the polarizer 101 and the effect of improving the durability of the circular polarizer can be expected. The boron content of the polarizer 101 is preferably 5.5 mass % or less, more preferably 5.0 mass % or less, and still more preferably 4.5 mass % or less. By making the boron content 5.5 mass % or less, shrinkage of the polarizer 101 by heating can be suppressed.

The boron content in the polarizer 101 can be obtained, for example, by dissolving a predetermined mass of the polarizer 101 in, for example, an aqueous solution of mannitol and titrating with an aqueous solution of NaOH. The method for determining the boron content of the polarizer 101 is described in detail in the embodiments of the specification of the present application.

The boron content of the polarizer 101 can be controlled by adjusting the boric acid concentration of the boric acid aqueous solution used in the above-mentioned boric acid treatment or the degree of rinsing of the boric acid aqueous solution in the above-mentioned cleaning step.

The "boric acid crosslinking index" of the polarizer 101 is preferably 0.5 or more, more preferably 0.8 or more, and still more preferably 1.0 or more. In this specification, the term "boric acid crosslinking degree index" refers to an index indicating to what extent polyvinyl alcohol molecular chains are crosslinked with boric acid in a polarizer composed of a polyvinyl alcohol-based resin film or the like . It can be said that the higher the value of the boric acid crosslinking index of the polarizer, the more the boric acid crosslinking between the polyvinyl alcohol molecular chains is going on. Keep iodine. As a result, the degree of polarization of the polarizer 101 can be easily prevented from decreasing, and the durability of the circular polarizer can be easily improved.

The boric acid crosslinking index of the polarizer 101 can be obtained by performing microscopic Raman spectroscopic analysis. In the microscopic Raman spectroscopic analysis, by using a laser Raman spectrophotometer (trade name: "NRS-5100", manufactured by Nippon Shoko Co., Ltd.), the current wavenumber of the polarizer at 780 cm ^-1 was obtained. The Raman scattered light intensity, and the Raman scattered light intensity at wavenumber 850 cm ^-1 were then calculated by dividing the Raman scattered light intensity at these wave numbers (that is, the Raman scattered light intensity at wave number 780 cm ^-1 ) The intensity of scattered light/the intensity of Raman scattered light at a wave number of 850 cm ^-1 ) can be used to calculate the boric acid crosslinking degree index.

Here, FIG. 6 is an explanatory diagram for explaining the micro-Raman spectroscopic analysis on the polarizing plate of the present embodiment. As shown in FIG. 6 , in the laser Raman spectrophotometer, the laser beam is incident on the end face of the polarizer 101 so that the traveling direction of the laser beam X is orthogonal to the absorption axis direction of the polarizer 101 . Here, the laser beam X is polarized in the thickness direction of the polarizer 101 . In addition, let the measurement position of the laser light be the position of the center of the thickness direction of the polarizer 101 . Moreover, it is preferable to perform the cross-sectional process of a polarizing plate using a microtome before Raman spectrometry. The so-called "Raman scattered light intensity at a wave number of 780 cm ^-1 " refers to the Raman scattered light intensity attributable to the bond between polyvinyl alcohol and boron, and the so-called "Raman scattered light intensity at a wave number of 850 cm ^-1 " refers to Refers to the Raman scattered light intensity attributed to polyvinyl alcohol.

In addition, various conditions used for the above-mentioned micro-Raman spectroscopic analysis are as follows.

Excitation wavelength: 532nm

Grating: 6001/mm

Slit width: 100×1000 μm

40μm Aperture:

40 μm

Objective lens: 100 times

The luminous factor correction polarization degree Py of the polarizer 101 is usually above 95%, preferably above 97%, more preferably above 98%, still more preferably above 98.7%, still more preferably above 99.0%, especially good 99.4% or more, or 99.9% or more. The luminous factor corrected polarization degree Py of the polarizer 101 may be less than 99.99%. The luminous factor correction polarization degree Py can be obtained by using a spectrophotometer with an integrating sphere (Japan Spectrophotometer Co., Ltd. Co., Ltd. "V7100") was calculated by performing luminous factor correction with a 2-degree field of view (C light source) of "JIS Z 8701" for the obtained polarization degree.

If the luminous factor correction polarization degree Py of the polarizer 101 is increased, it is advantageous to improve the function of the circular polarizer as an anti-reflection film and the durability of the circular polarizer. If the luminous factor correction polarization degree Py of the polarizer 101 is less than 95%, it may not be able to function as an anti-reflection film.

The luminous factor correction monomer transmittance Ty of the polarizer 101 is usually above 41%, preferably above 41.1%, more preferably above 41.2%, and may be above 42% or above 42.5%. The luminous factor corrected single transmittance Ty of the polarizer 101 is usually 50% or less, 48% or less, 46% or less, 44% or less, or 43% or less. If the transmittance Ty of the luminous factor correction monomer is too high, the luminous factor correction polarization degree Py will be too low, and the circular polarizer cannot function as an anti-reflection film. The luminous factor correction monomer transmittance Ty can be obtained by using a spectrophotometer with an integrating sphere (“V7100” manufactured by Nippon Shoko Co., Ltd.) with a 2-degree field of view of “JIS Z 8701”. (C light source) is calculated by performing luminous factor correction.

(2-2) Protective film

The protective film 102 laminated on one side of the polarizer 101 is a film for protecting the polarizer, for example, a translucent (preferably optically transparent) film formed of a thermoplastic resin can be used.

Examples of thermoplastic resins include: cellulose resins such as triacetate cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyether resins; polyether resins; Polycarbonate resin; Polyamide resin such as nylon or aromatic polyamide; Polyimide resin; Polyolefin resin such as polyethylene, polypropylene, ethylene/propylene copolymer; Polyolefin resins (also known as norbornene-based resins); (meth)acrylic resins; polyarylate resins; polystyrene resins; polyvinyl alcohol resins, and mixtures thereof.

The protective film 102 is preferably a cyclic polyolefin-based resin film, a polyethylene terephthalate film, or a polycarbonate film, and more preferably a cyclic polyolefin-based resin film.

The protective film 102 preferably has no retardation characteristic or a small retardation value. Specifically, the in-plane retardation value of the protective film 102 at a wavelength of 550 nm is preferably 0 nm to 10 nm, and the retardation value in the thickness direction at a wavelength of 550 nm is preferably -10 nm to +10 nm. In the circular polarizing plate of the present invention, when the hard coating layer 103 is provided as in the circular polarizing plate 3, the laminate of the protective film 102 and the hard coating layer 103 is preferably a film with a small retardation value as described above.

The thickness of the protective film 102 is preferably 2 μm or more, more preferably 3 μm or more, still more preferably 5 μm or more, and may be 10 μm or more. The thickness of the protective film 102 is preferably 50 μm or less, more preferably 40 μm or less, and still more preferably 30 μm or less.

The light transmittance of the protective film 102 to visible light is required to be the general one in the technical field of polarizing plates. For example, the light transmittance to visible light is preferably above 85%, more preferably above 90%. When the circular polarizing plate of the present invention has the hard coating layer 103 like the circular polarizing plate 3, the laminate of the protective film 102 and the hard coating layer 103 preferably has the above-mentioned light transmittance.

If the protective film 102 or the laminate of the protective film 102 and the hard coat layer 103 has a small retardation value and a high light transmittance, the luminous factor of the polarizer 101 corrects the polarization degree Py or the luminous factor corrects the single transmittance Ty can be replaced by "the polarizer 10 formed by laminating the polarizer 101 and the protective film 102" or "the polarizer 11 formed by laminating the polarizer 101, the protective film 102 and the hard coat layer 103" respectively. The factor-corrected polarization degree Py or the luminous factor-corrected monomer transmittance Ty.

From the viewpoint of suppressing migration of iodine, the distance from the side surface of the retardation layer structure 20 of the polarizer 101 to the side surfaces of the linear polarizers 10 and 11 of the retardation layer structure 20 is preferably 3 μm or more, More preferably, it is 4 μm or more, more preferably 5 μm or more, and still more preferably 10 μm or more. The distance is preferably 40 μm or less, and more preferably 30 μm or less, from the viewpoints of thinning and bending resistance (flexibility) of the circularly polarizing plate.

In the circularly polarizing plate of the present invention, preferably, any layer other than the polarizer has light selective absorption. One layer or two or more layers may have light selective absorptivity. In the circular polarizing plate of the present invention, the layer between the polarizer 101 and the retardation layer structure 20 (typically, the layer between the polarizer 101 and the liquid crystal hardening layer 201 (that is, the protective film 102, The hard coat layer 103 or the first bonding layer 30a)) has light selective absorption properties. Among these layers, one layer or two or more layers may have light selective absorption. In the present specification, "having light selective absorption" preferably means having absorptivity for ultraviolet rays having a wavelength of 350 nm or the like, and more preferably means having absorptivity for ultraviolet rays having a wavelength of 350 nm or the like and visible light having a short wavelength around 410 nm. .

If the protective film 102 has light selective absorptivity (preferably absorbs ultraviolet rays with a wavelength of 350 nm or the like, more preferably absorbs ultraviolet rays with a wavelength of 350 nm or the like and visible light with short wavelengths around 410 nm), the following It is advantageous in terms of characteristics.

1) When a circularly polarizing plate is applied to an image display device, the image display element can be protected from ultraviolet rays or short-wavelength visible light.

II) Changes in the retardation value of the retardation layer structure 20 due to ultraviolet rays or short-wavelength visible light can be suppressed.

III) The reflection hue of the circular polarizer can be adjusted by absorbing short wavelength visible light.

IV) Deterioration of the polarizer 101 due to light reflected by image display elements such as organic EL display elements can be prevented.

If it is desired to impart light selective absorption to the protective film 102, it can be carried out by "using a thermoplastic resin having light selective absorption as the thermoplastic resin constituting the protective film 102", or by "encapsulating the protective film 102" It can be carried out by containing an additive (light absorber) having light selective absorption properties, or it can be carried out by using both of them. When imparting light selective absorption to the protective film 102 , it is preferable to carry out at least by including a light absorber in the protective film 102 .

Specific examples of preferable light absorbers are listed below. Among the light absorbers, in the present invention, it is preferable to use a light absorber for light with a wavelength of 350 nm (ultraviolet rays) or a light absorber for light with a wavelength of 410 nm from the viewpoint of the above-mentioned preferable light selective absorption. agent.

As for the light absorber for light having a wavelength of 350 nm, various ultraviolet absorbers are readily available on the market. Examples of such ultraviolet absorbers include oxybenzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. Organic UV absorbers such as absorbers and triazine-based UV absorbers. More specifically, 5-chloro-2-(3,5-di-2-butyl-2-hydroxyphenyl)-2H-benzotriazole, (2-2H-benzotriazole-2 -yl)-6-(straight-chain and side-chain dodecyl)-4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone Ketones etc.

As the ultraviolet absorber, a commercially available product can be used as it is. As such commercial products, for example, triazine-based ultraviolet absorbers include "Kemisorb 102" manufactured by Chemipro Chemical Co., Ltd., "ADEKA STAB LA46", "ADEKA STAB LAF70", BASF manufactured by ADEKA Co., Ltd. "TINUVIN 109", "TINUVIN 171", "TINUVIN 234", "TINUVIN 326", "TINUVIN 327", "TINUVIN 328", "TINUVIN 928", "TINUVIN 400", "TINUVIN 460", " "TINUVIN 405", "TINUVIN 477" (both are trade names), etc. Examples of the benzotriazole-based ultraviolet absorber include "ADEKA STAB LA31" and "ADEKA STAB LA36" (both are trade names) manufactured by ADEKA Co., Ltd., "SUMISORB 200" manufactured by Sumika Chemtex Co., Ltd., "SUMISORB 250", "SUMISORB 300", "SUMISORB 340" and "SUMISORB 350" (any of them are trade names), "Kemisorb 74", "Kemisorb 79" and "Kemisorb 279" by CHEMIPRO Chemical Co., Ltd. (any of them are are trade names), "TINUVIN 99-2", "TINUVIN 900" and "TINUVIN 928" (all are trade names) manufactured by BASF Corporation. Moreover, two or more types of ultraviolet absorbers may be used in combination for the circularly polarizing plate of the present invention, and different light absorbers may be used for the plural layers constituting the circularly polarizing plate of the present invention.

The ultraviolet absorber may be an inorganic ultraviolet absorber. Inorganic ultraviolet absorbers include titanium oxide, zinc oxide, indium oxide, tin oxide, talc, kaolin, calcium carbonate, titanium oxide-based composite oxide, zinc oxide-based composite oxide, and ITO (tin-doped indium oxide) , ATO (tin oxide doped with antimony), etc. The titanium oxide-based composite oxides include, for example, zinc oxide doped with silicon dioxide and aluminum oxide. These inorganic ultraviolet absorbers may be used in combination of two or more types, and may be used in combination with, for example, commercially available light absorbers (organic ultraviolet absorbers) exemplified above.

As a light absorber for light with a wavelength of 410 nm, a compound having a maximum absorption wavelength in the wavelength band of 360 to 430 nm can be synthesized according to a known method and used in the present invention. As such a light absorber, for example, a compound known as a light selective absorbing compound described in JP-A No. 2017-120430 can be used. It is preferable to include a compound having at least one absorption maximum at a wavelength of 360 nm to 420 nm, and it is more preferable to include a compound having an absorption maximum at a wavelength of 380 nm to 410 nm.

The amount of the light absorbing agent used is selected in such a way as to avoid significantly impairing the light transmittance of the layer containing the light absorbing agent to visible light. For example, when the mass of the layer is set to 100 parts by mass, the The light absorber contained in the layer is generally 0.01 to 20 parts by mass, preferably 0.05 to 15 parts by mass, and more preferably 0.1 to 10 parts by mass.

In the circular polarizing plate of the present invention, the layered body (protective film 102, hard coat layer 103 and first bonding layer 30a) between the polarizer and the liquid crystal hardening layer preferably has an absorbance at a wavelength of 350 nm of 0.5 The above is more preferably 1.0 or more, and the absorbance at a wavelength of 410 nm is preferably 0.2 or more, more preferably 0.5 or more, and may be 2.0 or less, or 1.5 or less.

In another embodiment, in the circularly polarizing plate of the present invention, a laminate of layers other than the polarizer (eg, the protective film 102, the hard coat layer 103, the first bonding layer 30a, the first liquid crystal cured layer 201, the second bonding layer 30b, the second liquid crystal curing layer 202, and the layered product composed of the third bonding layer 30c), that is, the layered product of the layer existing on the protective film side when the polarizer is used as a reference, which The absorbance at a wavelength of 350 nm is preferably 0.3 or higher, more preferably 0.5 or higher, still more preferably 1.0 or higher, still more preferably 2.0 or higher, and particularly preferably 3.0 or higher. Its absorbance at a wavelength of 410 nm is preferably 0.2 or higher, more preferably 0.5 or higher, still more preferably 0.7 or higher, generally 2.0 or lower, and may be 1.5 or lower.

The protective film 102 can be laminated on the polarizer 101 via an adhesive layer. As the adhesive for forming the adhesive layer, a water-based adhesive or an active energy ray-curable adhesive described later can be used. Examples of the water-based adhesive include those obtained by dissolving or dispersing a polyvinyl alcohol-based resin in water. In addition, from the viewpoint of easily securing the adhesiveness, the thickness of the adhesive layer between the protective film 102 and the polarizer 101 is usually 0.01 μm or more, and usually 10 μm or less. As described above, when the circular polarizing plate of the present invention is applied to a flexible image display device, the thickness of each member constituting the circular polarizing plate is preferably thinner, but if the thickness of the adhesive layer becomes extremely thin , there is a risk of compromising the desired continuity. Therefore, the thickness of the adhesive layer should be optimized in consideration of "flexibility when the circular polarizer of the present invention is applied to a flexible image display device" and "adhesion between the polarizer 101 and the protective film 102" change.

(2-3) Hard coating

The circularly polarizing plate system may further have a hard coat layer 103 between the protective film 102 and the liquid crystal hardened layer (retardation layer structure 20 ). The hard coat layer 103 is preferably laminated on the side surface of the retardation layer structure 20 of the protective film 102, and more preferably is directly laminated on the surface.

The hard coat layer 103 can be formed by hardening a hard coat composition including a reactive material that forms a cross-linked structure by irradiating active energy rays or thermal energy. The hard coating composition is preferably cured by irradiation with active energy rays. In this specification, "active energy rays" include visible light, ultraviolet rays, infrared rays, X-rays, alpha rays, beta rays, gamma rays, electron beams, and the like, and are preferably ultraviolet rays.

The hard coat composition contains a polymer of at least one of a radically polymerizable compound and a cationically polymerizable compound. The "radical polymerizable compound" refers to a compound having a radically polymerizable group. The radically polymerizable group which the radically polymerizable compound has is only a functional group capable of generating a radical polymerization reaction, and examples thereof include a group containing a carbon-carbon unsaturated double bond. Specifically, a vinyl group, a (meth)acryloyl group, etc. are mentioned.

From the viewpoint of high reactivity, the radically polymerizable compound is preferably a compound having a (meth)acryloyl group, and it is preferable to use a compound having 2 to 6 (meth)acryloyl groups in one molecule. based on compounds known as multifunctional acrylate monomers, or as epoxy (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates An oligomer having a molecular weight of several hundreds to thousands of (meth)acryloyl groups in the molecule. Preferably, it contains 1 or more types chosen from epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate.

The "cationically polymerizable compound" refers to a compound having a cationically polymerizable group such as an epoxy group, an oxetanyl group, and a vinyl ether group. The cationically polymerizable compound is preferably a compound having at least one of an epoxy group and an oxetanyl group as a cationically polymerizable group.

The cationically polymerizable compound having an epoxy group includes, for example, an alicyclic epoxy resin obtained by mixing polyglycidyl ether or cyclohexene-containing polyol having an alicyclic ring. Compounds of ring and cyclopentene ring obtained by epoxidizing appropriate oxidizing agents such as hydrogen peroxide and peroxyacid; aliphatic epoxy resins, which are polycyclic rings of aliphatic polyols or their alkylene oxide adducts Oxypropyl ether, polyglycidyl ester of aliphatic long-chain polybasic acid, homopolymer and copolymer of glycidyl (meth)acrylate, etc.; glycidyl ether ring derived from bisphenols Oxygen resin, which is obtained by combining "bisphenols such as bisphenol A, bisphenol F or hydrogenated bisphenol A, or their derivatives such as alkylene oxide adducts, caprolactone adducts, etc." with epichlorohydrin Glycidyl ether and novolak epoxy resin produced by reacting alcohol.

The hard coat composition may further contain a polymerization initiator. As the polymerization initiator, radical polymerization initiators, cationic polymerization initiators, and combinations thereof can be exemplified. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate radicals or cations, and perform radical polymerization and cationic polymerization.

Active energy ray radical polymerization initiators include "Type 1 radical polymerization initiators that generate radicals by molecular decomposition" and "Type 2 radicals that coexist with tertiary amines and react with tertiary amines to generate radicals by dehydrogenation. Radical polymerization initiators" can be used individually or in combination. The thermal radical polymerization initiator includes organic peroxides such as hydrogen peroxide and perbenzoic acid, azo compounds such as azobisbutyronitrile, and the like. The cationic polymerization initiators include aromatic iodonium salts, aromatic periconium salts, cyclopentadienyl iron (II) complexes, and the like.

The content of the polymerization initiator is, for example, 0.1 to 10 mass % with respect to the entire hard coat composition (100 mass %). If the content of the polymerization initiator is less than 0.1 mass %, hardening cannot be sufficiently advanced, and there is a possibility that the mechanical properties and adhesion of the hard coat layer 103 finally obtained may be insufficient.

The hard coating composition may further contain solvents, additives, and the like. The additives include inorganic particles, leveling agents, stabilizers, surfactants, antistatic agents, lubricants, antifouling agents, and the like.

The thickness of the hard coat layer 103 is preferably 0.5 μm or more, more preferably 1 μm or more, from the viewpoint of suppressing possible scratches that may occur when the circular polarizing plate of the present invention is transported or processed. Still more preferably, it is 3 μm or more, but may be 5 μm or more. From the viewpoints of bending resistance (flexibility) and production efficiency, the thickness of the hard coat layer 103 is preferably 30 μm or less, more preferably 20 μm or less, and still more preferably 10 μm or less.

The hard coat layer 103 may have light selective absorption. Preferably, at least one of the protective film 102 and the hard coat layer 103 has light selective absorptivity, and both may have light selective absorptivity. The advantage that the hard coat layer 103 has light selective absorption is the same as when the protective film 102 has light selective absorption. In order to impart light selective absorption to the hard coat layer 103, it can be performed by making the hard coat layer 103 contain the above-mentioned light absorber.

The protective film 102 having the hard coat layer 103 containing a light absorber (protective film with a hard coat layer) can be purchased from the market, or the protective film with a hard coat layer can be used as it is as a member of the circular polarizing plate of the present invention. Similarly, the protective film 102 which does not have the hard coat layer 103 but contains a light absorber can also be obtained. In such a protective film or a protective film with a hard coat, although the content of the light absorber contained in it is not clear, in this case, the content of the protective film or the protective film with a hard coat can be considered. The best is chosen for the light penetration of visible light.

(3) Retardation layer structure

The retardation layer structure 20 is a structure including at least one liquid crystal cured layer (a cured product layer obtained by polymerizing and curing a polymerizable liquid crystal compound). As shown in FIGS. 2 and 3 , the retardation layer structure 20 preferably includes a first liquid crystal curing layer 201 and a second liquid crystal curing layer 202 , and the circular polarizer preferably includes a polarizer 101 , a protection The film 102 , the first liquid crystal cured layer 201 and the second liquid crystal cured layer 202 .

The liquid crystal cured layer is a layer (retardation layer) having retardation properties, and is a cured product layer that polymerizes and cures a polymerizable liquid crystal compound in an oriented state and exhibits retardation properties. The retardation layer structure 20 may include at least one liquid crystal cured layer, and may include two or more liquid crystal cured layers. When including two or more liquid crystal cured layers, the retardation layer structure 20 may include a bonding layer (second bonding layer 30b) for bonding these liquid crystal cured layers to each other.

The liquid crystal hardening layer may be a 1/2 wavelength retardation layer, a 1/4 wavelength retardation layer, or a positive C plate. The 1/4 wavelength retardation layer may have reverse wavelength dispersion. When the retardation layer structure 20 includes two or more liquid crystal cured layers, the liquid crystal cured layers may have the same retardation characteristics or may have different retardation characteristics.

The retardation layer structure 20 preferably includes the first liquid crystal cured layer 201 and the second liquid crystal cured layer 202 as described above. The first liquid crystal cured layer 201 and the second liquid crystal cured layer 202 are, for example, a 1/2 wavelength retardation layer and a 1/4 wavelength retardation layer, respectively. Alternatively, one of the first liquid crystal cured layer 201 and the second liquid crystal cured layer 202 is a 1/4 wavelength retardation layer of reverse wavelength dispersion, and the other is a positive C plate. For example, the 1st liquid crystal cured layer 201 and the 2nd liquid crystal cured layer 202 are respectively the 1/4 wavelength retardation layer of reverse wavelength dispersibility, and a positive C plate.

The polymerizable liquid crystal compound includes a rod-shaped polymerizable liquid crystal compound and a disc-shaped polymerizable liquid crystal compound, and one of them may be used, or a mixture containing both of them may be used. When the rod-shaped polymerizable liquid crystal compound is oriented horizontally or vertically with respect to the base material layer, the optical axis of the polymerizable liquid crystal compound is aligned with the long axis direction of the polymerizable liquid crystal compound. When the discotic polymerizable liquid crystal compound is oriented, the optical axis of the polymerizable liquid crystal compound exists in a direction orthogonal to the disc plane of the polymerizable liquid crystal compound. As the rod-shaped polymerizable liquid crystal compound, for example, those described in JP-A No. 11-513019 (claim 1, etc.) can be suitably used. Disc-shaped polymerizable liquid crystal compound As the material, those described in JP 2007-108732 A (paragraphs [0020] to [0067], etc.) and JP 2010-244038 A (paragraphs [0013] to [0108], etc.) can be suitably used.

What is necessary is just to orientate a polymerizable liquid crystal compound in a suitable direction, if it wants to express an in-plane retardation in the liquid crystal cured layer formed by superposing|polymerizing a polymerizable liquid crystal compound. When the polymerizable liquid crystal compound is rod-shaped, the in-plane retardation is exhibited by orienting the optical axis of the polymerizable liquid crystal compound horizontally with respect to the plane of the substrate layer. In this case, the optical axis direction and the slow axis direction are Consistent. When the polymerizable liquid crystal compound is disc-shaped, the optical axis of the polymerizable liquid crystal compound is oriented horizontally with respect to the plane of the substrate layer to exhibit in-plane retardation. In this case, the optical axis and the slow axis are Orthogonal. The alignment state of the polymerizable liquid crystal compound can be adjusted by the combination of the alignment layer and the polymerizable liquid crystal compound.

The polymerizable liquid crystal compound is a compound having at least one polymerizable group and having liquid crystallinity. When two or more types of polymerizable liquid crystal compounds are used in combination, it is preferable that at least one type has two or more polymerizable groups in the molecule. The "polymerizable group" refers to a group that participates in a polymerization reaction, and a photopolymerizable group is preferred. Here, the "photopolymerizable group" refers to a group that can participate in a polymerization reaction by an active radical, an acid, or the like generated from a photopolymerization initiator described later. The polymerizable group includes vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloxy, methacryloyloxy, oxiranyl ( oxiranyl), oxetanyl, styryl, allyl and the like. Among them, acryloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferable, and acryloxy group is more preferable. The liquid crystallinity of the polymerizable liquid crystal compound can be either a thermotropic liquid crystal or a lyotropic liquid crystal. If the thermotropic liquid crystal is classified according to the degree of order, it can be a nematic liquid crystal or a nematic liquid crystal. Smectic liquid crystal.

The retardation layer structure 20 may include an alignment layer. The alignment layer has an alignment-adjusting power to align the polymerizable liquid crystal compound in a desired direction. In the case of the alignment layer, it can be a polymerizable liquid crystal compound A vertical alignment layer in which the molecular axis of the material is vertically aligned with respect to the substrate layer, a horizontal alignment layer in which the molecular axis of the polymerizable liquid crystal compound is aligned horizontally relative to the substrate layer, or a horizontal alignment layer in which the molecular axis of the polymerizable liquid crystal compound is aligned horizontally relative to the substrate layer. The molecular axis is an obliquely oriented layer in which the molecular axis is oriented obliquely with respect to the base material layer. When the retardation layer structure 20 includes two or more alignment layers, the alignment layers may be the same or different.

The alignment layer preferably has solvent resistance that is not dissolved by coating or the like of the composition for forming a liquid crystal layer containing a polymerizable liquid crystal compound, and has a resistance to solvent removal or alignment of the polymerizable liquid crystal compound. Heat resistant to heat treatment. Examples of the alignment layer include: an alignment polymer layer formed of an alignment polymer, a photoalignment polymer layer formed of a photoalignment polymer, a groove having a concavo-convex pattern or a plurality of grooves (grooves) on the surface of the layer Orientation layer.

The thickness of the liquid crystal cured layer (first and second liquid crystal cured layers) may be 0.1 μm or more, 0.5 μm or more, 1 μm or more, 2 μm or more, and preferably 10 μm or less, may be 8 μm or less, or 5 μm or less.

A liquid crystal cured layer can be formed by apply|coating the composition for liquid crystal layer formation containing a polymerizable liquid crystal compound on a base material layer, drying, and polymerizing a polymerizable liquid crystal compound. The composition for forming a liquid crystal layer can be applied on the alignment layer formed on the base material layer.

As the base material layer, a film formed of a resin material can be used, for example, a film using a resin material described as the thermoplastic resin used for forming the protective film 102 described above. The thickness of the base material layer is not particularly limited, but is generally preferably 1 to 300 μm , more preferably 20 to 200 μm , from the viewpoint of workability such as strength and handleability. The base material layer can be assembled into the circular polarizer together with the liquid crystal hardened layer, or the base material layer can be peeled off and only the liquid crystal hardened layer or the liquid crystal hardened layer and the alignment layer can be assembled into the circular polarizer.

The second bonding layer 30b is an adhesive layer or an adhesive layer. The second bonding layer 30b is preferably an adhesive layer, more preferably an adhesive layer obtained by curing an active energy ray-curable adhesive, and more preferably an adhesive layer obtained by curing a UV-curable adhesive Floor. When the second bonding layer 30b is used as the adhesive layer, it is preferable to suppress the occurrence of wrinkles in the liquid crystal cured layer when the circularly polarizing plate is bent or folded. As the adhesive layer, those described later can be used.

As an active energy ray hardening type adhesive agent, the solventless active energy ray hardening type adhesive agent which contains the curable compound hardened by active energy ray irradiation is mentioned, for example.

The active energy ray-curable adhesive preferably contains either or both of a cationically polymerizable curable compound and a radically polymerizable curable compound because it exhibits good adhesiveness. The active energy ray-curable adhesive may further contain a cationic polymerization initiator such as a photocationic polymerization initiator for initiating a curing reaction of the curable compound, or a radical polymerization initiator.

Examples of the cationically polymerizable curable compound include epoxy-based compounds such as alicyclic epoxy compounds having an epoxy group bonded to an alicyclic ring, two or more epoxy groups and no aromatic ring. Polyfunctional aliphatic epoxy compounds, monofunctional epoxy groups with one epoxy group (except those included in alicyclic epoxy compounds), with two or more epoxy groups and as many as aromatic rings Functional aromatic epoxy compounds, etc.; oxetane compounds having one or more oxetane rings in the molecule; combinations thereof.

Examples of radically polymerizable curable compounds include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule), radically polymerizable compounds Other vinylic compounds with double bonds, or combinations thereof.

The thickness of the second bonding layer 30b is not particularly limited. For example, it may be 2 μm or more and 30 μm or less, preferably 3 μm or more and 20 μm or less. For example, it may be 10 μm or more, but from the viewpoint of thinner thickness, it is 15 μm or less, preferably 10 μm or less, and particularly preferably 7 μm or less. When the second bonding layer 30b is an adhesive layer, its thickness is preferably 0.1 μm or more, and may be 0.5 μm or more, and preferably 10 μm or less, and may be 5 μm or less.

(4) The first bonding layer and the third bonding layer

The first bonding layer 30a is an adhesive layer or an adhesive layer, preferably an adhesive layer. The first bonding layer 30 a joins the linear polarizers 10 and 11 and the retardation layer structure 20 . The third bonding layer 30c is usually an adhesive layer. The third bonding layer 30c can be used to bond the circularly polarizing plate to the image display element. The circularly polarizing plate preferably comprises a polarizer 101, a protective film 102, a liquid crystal hardening layer (a first liquid crystal hardening layer, and a second liquid crystal hardening layer) and an adhesive layer (the third bonding layer 30c) in sequence, more preferably The polarizer 101, the protective film 102, the hard coat layer 103, the liquid crystal hardening layer (1st liquid crystal hardening layer, further is a 2nd liquid crystal hardening layer) and an adhesive layer (3rd bonding layer 30c) are included in this order.

The thickness of the adhesive layer belonging to the first bonding layer 30a may be, for example, 2 μm or more and 30 μm or less, preferably 3 μm or more and 20 μm or less. For example, it may be 10 μm or more, but from the viewpoint of thinner thickness, it is 15 μm or less, preferably 10 μm or less, and particularly preferably 7 μm or less. When the first bonding layer 30a is an adhesive layer, its thickness is preferably 0.1 μm or more, and may be 0.5 μm or more, and preferably 10 μm or less, and may be 5 μm or less.

The first bonding layer 30a may have light selective absorption. Preferably, at least one of the protective film 102, the hard coat layer 103, and the first bonding layer 30a has light selective absorption, and a plurality of them may have light selective absorption. The advantage that the first bonding layer 3aa has light selective absorption is the same as when the protective film 102 has light selective absorption. In order to provide light selective absorption to the 1st bonding layer 30a, it can carry out by containing the said light absorber in the 1st bonding layer 30a.

The thickness of the adhesive layer belonging to the third bonding layer 30c is not particularly limited, and can be appropriately set according to the application, but may be, for example, 250 μm or less, and preferably 100 μm from the viewpoint of thinning Hereinafter, it is more preferably 50 μm or less, more preferably 40 μm or less, particularly preferably 30 μm or less, and still more preferably 20 μm or less. The lower limit of the thickness of the adhesive layer is not particularly limited, but from the viewpoint of durability, it may be, for example, 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and still more The best series is 14 μm or more.

As for the adhesive, conventionally known adhesives with excellent optical transparency can be used, for example, (meth)acrylic, urethane, polysiloxane, polyvinyl ether can be used. Adhesives for base polymers, etc. Moreover, an active energy ray hardening type adhesive agent, a thermosetting type adhesive agent, etc. may be sufficient. Among them, it is preferable to use (meth)acrylic resin excellent in transparency, adhesive force, re-peelability (hereinafter also referred to as reworkability), weather resistance, heat resistance, etc. as the adhesive of the base polymer. The adhesive layer is preferably composed of a reaction product of an adhesive containing a (meth)acrylic resin, a crosslinking agent, and a silane compound, and may contain other components.

The adhesive layer can be formed using an active energy ray-curable adhesive. Active energy ray-curable adhesives can be formed by mixing ultraviolet curable compounds such as polyfunctional (meth)acrylates in the above-mentioned adhesives, and irradiating ultraviolet rays to cure them after forming the adhesive layer, thereby forming a harder adhesive. adhesive layer. Active energy ray-curable adhesives have the property of being hardened when irradiated with energy rays such as ultraviolet rays or electron beams. The active energy ray hardening type adhesive has adhesiveness even before energy ray irradiation, so it is an adhesive having the property of being able to adhere to a to-be-adhered body, hardening by energy ray irradiation, and adjusting the adhesive force.

The salvage energy ray curable adhesive generally contains a (meth)acrylic adhesive and an energy ray polymerizable compound as main components. Usually, a crosslinking agent is further prepared, and a photopolymerization initiator, a photosensitizer, etc. can also be prepared as required.

(5) Separation membrane

The circularly polarizing plate may include a separation film 203 for protecting the outer surface of the third bonding layer 30c. Examples of the separation film 203 include a film obtained by subjecting the surface of the base film on the third bonding layer 30c side to release treatment such as polysiloxane treatment. The base film system is, for example, a film composed of polyethylene-based resins such as polyethylene, polypropylene-based resins such as polypropylene, polyester-based resins such as polyethylene terephthalate, and the like.

<Optical laminate>

The optical layered product of the present invention (hereinafter also simply referred to as "optical layered product") includes the above-described circularly polarizing plate of the present invention and other components. Other components can be listed as: the image display element 40, which is arranged on the side of the liquid crystal hardening layer of the circular polarizer, that is, on the side opposite to the recognition side of the circular polarizer (refer to FIG. 4, FIG. 5); The front panel 50 is arranged on the polarizer 101 side of the circular polarizer, more specifically on the surface of the polarizer 101 belonging to the outermost surface of the circular polarizer (refer to FIG. 5 ); the protective film (also referred to as the It is called "surface protection film"), which is used to temporarily protect the surface of the polarizer 101 .

The optical layered body preferably includes one or more selected from the group consisting of the front panel 50 and the image display element 40 as the other constituent elements described above.

<Image Display Device>

The circular polarizers 1, 2, and 3 are disposed on the front (recognition side) of the image display element, and can be used as a constituent element of the image display device. The circular polarizing plate can also be used as an anti-reflection polarizing plate for imparting an anti-reflection function in an image display device. The image display device is not particularly limited, and examples thereof include image display devices such as organic electroluminescence (organic EL) display devices, inorganic electroluminescence (inorganic EL) display devices, liquid crystal display devices, and electroluminescence display devices. Hereinafter, the important part regarding the aspect which applies the circular polarizing plate (circular polarizing plate 1, 2, 3) of this invention to an image display device (especially a flexible image display device) is demonstrated briefly.

The image display device may be a flexible image display device. The flexible image display device is composed of an optical laminate for a flexible image display device and an organic EL display element, which will be described later, and the optical laminate for a flexible image display device is arranged on the recognition side of the organic EL display element. and can be bent.

<Optical laminate for flexible image display device>

The optical laminate system for a flexible image display device is composed of "the circularly polarizing plate of the present invention" and "an organic EL display element belonging to an image display element having bending resistance". Moreover, the optical laminated body for flexible image display apparatuses is provided with the front panel with bending resistance. Furthermore, there are cases where a touch sensing panel is provided as an input means. In this case, the stacking sequence of the circular polarizer, the front panel, and the touch sensing panel can be, for example, the front panel, the circular polarizing panel, and the touch sensing panel in sequence from the identification side. The stacking sequence is preferably a front panel, a touch sensing panel, and a circular polarizer. If the circular polarizer is located closer to the recognition side than the touch-sensing panel, the wiring pattern of the touch-sensing panel is not easily recognized and the visibility of the displayed image is improved, which is preferable. . The individual members can be laminated using an adhesive, an adhesive, or the like. Moreover, the optical laminated body for flexible image display devices may have a light-shielding pattern formed on "at least one surface of any layer of the front panel, the polarizer, and the panel of the touch sensor".

<Front Panel>

In the image display device, a front panel may be disposed on the recognition side of the circular polarizer. The front panel is usually laminated on the polarizer 101 of the circularly polarizing plate of the present invention via an adhesive layer or an adhesive layer.

As a front panel, what consists of glass or a resin film may be mentioned, and a hard-coat layer may be contained in at least one side of these. As the glass system, for example, high-transmission glass or tempered glass can be used. When a particularly thin transparent surface material is used, chemically strengthened glass is preferred. The thickness of the glass can be set to, for example, 100 μm to 5 mm.

When the circularly polarizing plate of the present invention is applied to a flexible image display device, the front plate to be used is required to have flexibility (flexible property). From this viewpoint, the front panel is preferably made of a resin film, and as described above, a hard coat layer may be included on at least one surface thereof. The front panel including the hard coat layer and composed of the resin film is not as rigid as the known glass, and can have the property of being flexible. The thickness of the hard coat layer in this case is not particularly limited as long as it is within a range that does not impair flexibility, and may be, for example, 5 to 100 μm .

The material used as the resin film of the front panel may be the same as the material exemplified as the material of the protective film 102 described above. Of course, two or more kinds of materials may be used, as long as it is a practical film of light transmittance. For the resin film of such a material, the thickness and the like can be optimized in consideration of light transmittance, flexibility, durability, and the like. The front panel is preferably one that does not have retardation properties (unstretched film), but may be a 1-axis or 2-axis stretched film as long as the retardation value is acceptable. Among them, the resin film used for the front panel is preferably a polyimide film or a polyimide film, a uniaxially or biaxially stretched polyester film, which is excellent in transparency and heat resistance, and is excellent in transparency and heat resistance. And it can correspond to the cycloolefin type derivative film, the polymethyl methacrylate film, and the transparent and non-optically anisotropic triacetate cellulose and isobutyl cellulose film of the enlargement of the film. The thickness of the resin film in this case is 5 to 200 μm , preferably 20 to 100 μm .

<Shading pattern>

The shading pattern is arranged on a part of the periphery of the image display surface of the image display device called a bezel, so that the observer does not recognize the image when viewing the image from the image display surface side. It is arranged for reasons such as wiring. Such a light-shielding pattern is formed on at least one surface of either the front plate or the circularly polarizing plate constituting the optical laminate for an image display device. When a touch-sensing panel is installed in the optical laminate for an image display device as an input means, a light-shielding pattern is also installed in the touch-sensing panel. As mentioned above, the shading pattern can hide the wirings of the display device from being recognized by the user. The color or material of the shading pattern is not particularly limited, and it can be formed of resin substances with various colors such as black, white, and gold. In one embodiment, the thickness of the shading pattern may be 2 μm to 50 μm , preferably 4 μm to 30 μm , and more preferably 6 μm to 15 μm . In addition, in order to suppress the mixing of air bubbles and the recognition of the boundary portion due to the level difference between the light-shielding pattern and the display portion, the light-shielding pattern may be given a shape.

<Touch Sensing Panel>

The image display device provided with the circular polarizing plate of the present invention may further be provided with a touch sensor as an input means. In this case, it is usually realized by assembling a touch sensor panel. Regarding the style of the touch sensor, various styles such as resistive film method, surface acoustic wave method, infrared method, electromagnetic induction method, and capacitive method have been proposed, and any of them may be used. Among them, the capacitive method is preferred. The capacitive touch sensor is divided into an "active area" and an "inactive area located at the outer portion of the active area". The active area corresponds to the area (display part) where the screen is displayed on the display panel, and is the area that senses the user's touch, and the inactive area corresponds to the area (non-display part) where the image is not displayed on the display device. area. The touch sensing panel may include the following: a substrate, which has flexibility; a sensing pattern, which is formed in an active area of the substrate; each sensing line, which is formed in an inactive area of the substrate, and It is used to connect with the external driving circuit through the above-mentioned sensing pattern and pad part. For the substrate with flexibility, the same material as the transparent substrate of the front panel 50 can be used. From the viewpoint of suppressing cracks that may occur in the touch-sensing panel, the substrate of the touch-sensing panel preferably has a ductility of 2,000 MPa% or more. More preferably, the ductility is 2,000 MPa% to 30,000 MPa%. Here, toughness is defined as the lower area of the curve up to the point of failure in the stress (MPa)-strain (%) curve (Stress-Strain Curve) obtained by the tensile test of the polymer material.

The fourth adhesive layer 30d shown in FIG. 5 is a bonding layer for bonding the "front plate 50" and the "polarizer 101 belonging to the uppermost layer of the circular polarizer". The description of the above-mentioned adhesive bond layer is cited for the fourth adhesive bond layer 30d.

The optical laminate (including the case where it is an optical laminate for a flexible image display device) may include a protective film for temporarily protecting the surface of the polarizer 101 . The protective film is composed of a base film and an adhesive layer laminated on the base film. The above description is cited for the adhesive layer. The resins constituting the base film may be, for example, polyethylene-based resins such as polyethylene, polypropylene-based resins such as polypropylene, and polyester-based resins such as polyethylene terephthalate or polyethylene naphthalate. , Polycarbonate resins and other thermoplastic resins. Preferred are polyester-based resins such as polyethylene terephthalate.

The optical laminate of the present invention (including the case where it is an optical laminate for a flexible image display device) and the circularly polarizing plate can be suitably applied to an image display device, especially an organic EL image display device.

[Example]

Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to these examples.

<Measurement method and evaluation method>

(1) Determination of boron content in polarizers

0.2 g of the polarizer was dissolved in 200 g of a 1.9 mass % mannitol aqueous solution. The obtained aqueous solution was titrated with 1 mol/L NaOH aqueous solution, and the boron content (mass %) of the polarizer was calculated by comparing the amount of NaOH solution required for neutralization with the calibration curve. The results are shown in Table 1.

(2) Calculation of boric acid crosslinking index

The cross section of the polarizing plate was processed using an ultramicrotome (trade name "LEICA Ultramicrotome EM UC7i" manufactured by LEICA). The position of the center in the thickness direction of the polarizer in the cross-section of the polarizing plate obtained was obtained by using a laser Raman spectrophotometer (trade name: "NRS-5100", manufactured by JASCO Corporation) under the following conditions, respectively. The Raman scattered light intensity at the wave number 780 cm ^-1 and the Raman scattered light intensity at the wave number 850 cm ^-1 were obtained ^, and then the Raman scattered light intensity at these wave numbers was divided and calculated (at the wave number 780 cm ^{-1 )} The intensity of Raman scattered light/the intensity of Raman scattered light at a wave number of 850 cm ⁻¹ ) was used to calculate the boric acid crosslinking degree index. The results are shown in Table 1.

Excitation wavelength: 532nm

Grating: 6001/mm

Slit width: 100×1000 μm

40μm aperture:

40 μm

Objective lens: 100 times

(3) Determination of moisture permeability of peelable film

The moisture permeability was measured according to JIS Z 0208. The temperature and humidity conditions were set at a temperature of 40° C. and a relative humidity of 90% RH.

(4) Determination of monomer transmittance and luminous factor corrected polarization degree

The single transmittance and luminous factor correction polarization degree of the circularly polarizing plate are made by making the linearly polarized light from Jihan enter the polarizer side of the circularly polarizing plate, and using a spectrophotometer with integrating sphere (manufactured by Nippon Shoko Co., Ltd., V7100) to measure. MD transmittance and TD transmittance were obtained in the wavelength range of 380 nm to 780 nm, and the monomer transmittance and polarization degree at each wavelength were calculated according to formula (A) and formula (B). Furthermore, the luminous factor correction was performed by the 2-degree field of view (C light source) of JIS Z 8701, and the luminous factor-corrected polarization degree (Py) was obtained. In addition, the so-called "MD transmittance" refers to the transmittance when the direction of the polarized light emitted from the Glan-Thompson prism is parallel to the transmission axis of the polarizing plate sample. In Formula (A) and Formula (B), "MD transmittance" is represented as "MD". In addition, the so-called "TD transmittance" refers to the transmittance when the direction of the polarized light emitted from the Glan-Thompson microscope is orthogonal to the transmission axis of the polarizing plate sample, and is expressed in the formula (A), formula In (B), the "TD penetration rate" is expressed as "TD".

Monomer penetration rate (%)=(MD+TD)/2 Formula (A)

Polarization degree (%)={(MD-TD)/(MD+TD)}×100 Formula (B)

(5) Heat resistance test of circular polarizing plate

The circular polarizing plate obtained in the Example was cut into a rectangle with a size of 140 mm×70 mm. At this time, it cut so that the absorption axis of a polarizer and the short side of a rectangle may become parallel. The cut circular polarizing plate was attached to an alkali-free glass with a thickness of 0.7 mm (manufactured by CORNING, serial number: EAGLE XG (registered trademark)) via an adhesive layer (2) to prepare a sample for evaluation. This evaluation sample was subjected to a heat resistance test in which it was stored for 500 hours under a dry condition at a temperature of 85° C., and the evaluation sample after the test was visually observed. The results were classified according to the following criteria and summarized in Table 1.

[Evaluation standard of heat resistance test]

A: Changes in appearance such as floating, peeling, and foaming were not observed.

B: Appearance changes such as floating, peeling, and foaming are slightly conspicuous.

C: Appearance changes such as floating, peeling, and foaming are clearly seen.

(6) Humidity and heat durability test of circular polarizing plate

The circular polarizing plate obtained in the Example was cut into a square with a size of 30 mm×30 mm. At this time, cutting was performed so that the absorption axis of the polarizer was parallel to the side of the square. The cut circular polarizing plate is attached to an alkali-free glass of 40 mm×40 mm (manufactured by CORNING, No.: EAGLE XG (registered trademark)) via the adhesive layer (2), and further separated on the polarizer surface. The adhesive layer was bonded to an alkali-free glass of 40 mm×40 mm (manufactured by CORNING, serial number: EAGLE XG (registered trademark)) to prepare a sample for evaluation. For this evaluation sample, measurement of the luminescence factor-corrected polarization degree Py was performed.

Next, with respect to this evaluation sample, a damp-heat durability test in which it was stored for 500 hours under the conditions of a temperature of 60° C. and a relative humidity of 95% RH was performed, and the evaluation sample after the test was subjected to a Determination of luminous factor corrected polarization degree Py. Table 1 shows the measured values of the luminescence factor-corrected polarization degree Py before and after the test, and the absolute value ΔPy of the difference between them.

(7) Weather resistance test of circular polarizing plate

The circular polarizing plate obtained in the Example was cut into a square with a size of 30 mm×30 mm. At this time, cutting was performed so that the absorption axis of the polarizer was parallel to the side of the square. The cut circular polarizing plate was bonded to an alkali-free glass of 40 mm×40 mm (manufactured by CORNING, serial number: EAGLE XG (registered trademark)) via the adhesive layer (2) to prepare a sample for evaluation. For this evaluation sample, the measurement of the 450 nm monomer transmittance was performed.

Next, a sample for evaluation was set on an aluminum plate (reflector plate) so as to irradiate ultraviolet rays from the polarizer 101 side, and put into a Sunshine weather meter under the conditions of a black panel temperature of 63° C. and a relative humidity of 50%. The weather resistance test was carried out for 120 hours (manufactured by SUGA Testing Machine Co., Ltd.). For the evaluation sample after the test, the measurement of the 450 nm monomer transmittance was carried out. Table 1 shows the absolute value of the difference between the measured values of the 450 nm monomer transmittance before and after the test.

(8) Absorbance measurement of laminate

In addition to the polarizer 101, the protective film 102, the hard coat layer 103, the first bonding layer 30a, the first liquid crystal cured layer 201, the second bonding layer 30b, the second liquid crystal cured layer 202, and the third bonding layer 30c The layers are laminated to produce a layered body. In addition, in the layer structure which does not have a hard-coat layer, the lamination|stacking of the hard-coat layer 103 is not performed. The laminated body is bonded to glass via the 3rd bonding layer 30c. After bonding the adhesive layer to a cycloolefin polymer (COP) film (ZF-14 manufactured by ZEON Co., Ltd.), the COP film was bonded to the protective film 102 via the adhesive layer. In this way, a layered body for evaluation was produced.

The layered product for evaluation was attached to a spectrophotometer UV-2450 (manufactured by Shimadzu Corporation), and the absorbance was measured in a wavelength range of 300 to 800 nm in 1 nm steps by the double beam method. Will Table 1 shows the absorbance at wavelengths of 350 nm and 410 nm of the produced laminate. In addition, the combined absorbance of the glass and the COP film of the adhesive at wavelengths of 350 nm and 410 nm is 0.06 or less, so it can be ignored.

<Preparation of the components of the circular polarizer>

(1) Production of polarizer 1

The polyvinyl alcohol film with a thickness of 20 μm , a degree of polymerization of 2400, and a degree of saponification of 99% or more is uniaxially stretched on a hot roll to a stretching ratio of 4.1 times, and in a tensioned state, relative to 100 parts by mass of water. In a dyeing bath containing 0.05 parts by mass of iodine and 5 parts by mass of potassium iodide, it was immersed at 28° C. for 60 seconds.

Then, it was immersed at 64 degreeC for 110 second in the boric acid aqueous solution 1 containing 5.5 mass parts of boric acid and 15 mass parts of potassium iodide per 100 mass parts of water. Then, it was immersed at 67 degreeC for 30 second in the boric-acid aqueous solution 2 containing 5.5 mass parts of boric acid and 15 mass parts of potassium iodide per 100 mass parts of water. Then, it wash|cleaned with the pure water of 10 degreeC, and it dried, and the polarizer 1 was obtained. The polarizer 1 had a thickness of 8 μm and a boron content of 4.3 mass %.

(2) Production of polarizer 2

The polyvinyl alcohol film with a thickness of 20 μm , a degree of polymerization of 2400, and a degree of saponification of 99% or more is uniaxially stretched on a hot roll to a stretching ratio of 4.1 times, and in a tensioned state, relative to 100 parts by mass of water. In a dyeing bath containing 0.05 parts by mass of iodine and 5 parts by mass of potassium iodide, it was immersed at 28° C. for 60 seconds.

Then, it was immersed at 64 degreeC for 110 second in the boric acid aqueous solution 1 containing 5.5 mass parts of boric acid and 15 mass parts of potassium iodide per 100 mass parts of water. Then, it was immersed at 67 degreeC for 30 second in the boric-acid aqueous solution 2 containing 2.3 mass parts of boric acid and 15 mass parts of potassium iodide per 100 mass parts of water. Then, it wash|cleaned with the pure water of 10 degreeC, and it dried, and the polarizer 2 was obtained. The polarizer 2 had a thickness of 8 μm and a boron content of 3.2 mass %.

(3) Preparation of protective film A, B, C, D, E and peelable film F

The following 5 types of protective films and 1 type of peelable film were prepared.

‧Protective film A: 27 μm thick cycloolefin film with a hard coat (COP-HC) with a hard coat thickness of 2 μm and a moisture permeability of 10g/m ² ‧24hr. Has UV absorption.

‧Protective Film B: Cyclic Olefin Film (COP) with a thickness of 25 μm . The moisture permeability is 12g/m ² ·24hr. Has UV absorption.

‧Protective film C: COP with a thickness of 23 μm . Does not have UV absorption.

‧Protective film D: COP with a thickness of 13 μm . Has UV absorption.

‧Protective film E: COP-HC with a thickness of 27 μm . It has ultraviolet absorptivity and absorbs visible light with short wavelengths around 410nm.

‧Peelable film F: TD80UL. Triacetin-based cellulose film manufactured by Fuji FILM Co., Ltd. The thickness is 80 μm , and the moisture permeability is 502g/m ² ·24hr.

(4) Production of linear polarizer 1

The protective film A was bonded to one side of the produced polarizer 1 through a water-based adhesive using a roll laminator, and the surface opposite to the protective film A side was bonded with a roll laminator through pure water. After the peelable film F, drying treatment was performed at 80° C. for 3 minutes. Then, the peelable film F was peeled from the polarizer, and the linear polarizing plate 1 which layered the protective film only on the single area of the polarizer 1 was obtained. The linear polarizer 1 is formed by laminating a polarizer 1, an adhesive layer, and a protective film A in this order.

(5) Production of linear polarizer 2

The linear polarizing plate 2 was produced in the same manner as the linear polarizing plate 1, except that the temperature of the drying process after bonding using a roll laminator was changed to 100°C.

(6) Production of linear polarizer 3

The linear polarizer 3 was produced in the same manner as the linear polarizer 1 except that the polarizer 1 was changed to the polarizer 2 .

(7) Production of linear polarizer 4

The linear polarizer 4 was produced in the same manner as the linear polarizer 2 except that the polarizer 1 was changed to the polarizer 2 .

(8) Production of linear polarizer 5

The linear polarizing plate 5 was produced in the same manner as the linear polarizing plate 1 except that the protective film A was changed to the protective film B.

(9) Production of linear polarizer 6

The linear polarizing plate 6 was produced in the same manner as the linear polarizing plate 1 except that the protective film A was changed to the protective film C.

(10) Production of linear polarizer 7

The linear polarizing plate 7 was produced in the same manner as the linear polarizing plate 1 except that the protective film A was changed to the protective film D.

(11) Production of linear polarizer 8

The linear polarizing plate 8 was produced in the same manner as the linear polarizing plate 1 except that the protective film A was changed to the protective film E.

(12) First liquid crystal cured layer A (production of 1/2 wavelength retardation layer)

On the base material layer formed of the transparent resin, the λ/2 alignment treatment is performed by applying the composition for forming an alignment layer and drying it. Then, a composition for forming a liquid crystal layer containing a discotic polymerizable liquid crystal compound is applied on the alignment layer, and the alignment of the polymerizable liquid crystal compound is fixed by heating and UV irradiation. A half wavelength retardation layer as a liquid crystal hardened layer was formed with a thickness of 2 μm .

(13) Second liquid crystal cured layer A (production of 1/4 wavelength retardation layer)

A composition for forming a liquid crystal layer containing a rod-shaped nematic polymerizable liquid crystal compound (liquid crystal monomer) is applied on the rubbing-treated alignment layer on the base material layer formed of a transparent resin, and by maintaining The state of refractive index anisotropy was cured, and a 1/4 wavelength retardation layer as a liquid crystal curing layer was formed on the alignment layer of the base material layer with a thickness of 1 μm .

(14) Preparation of Active Energy Ray Curable Adhesive A

After the following components were prepared and mixed, defoaming was performed to prepare an active energy ray-curable adhesive A.

[Cationically polymerizable compound]

‧Neopentyl glycol diglycidyl ether (trade name: EX-211L, manufactured by NAGASE CHEMTEX Co., Ltd.): 30 parts by mass

‧3-Ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane (trade name: OXT-221, manufactured by Toagosei Co., Ltd. ): 13 parts by mass

‧Bisphenol A epoxy resin (trade name: EP-4100E, ADEKA Co., Ltd., viscosity 13Pa‧s (temperature 25℃)): 12 parts by mass

‧Aromatic-containing oxetane compound (trade name: TCM-104, manufactured by TRONLY): 45 parts by mass

[Photocationic polymerization initiator]

‧CPI-100P, manufactured by SAN-APRO Co., Ltd., 50% propylene carbonate solution: 2.25 parts by mass (solid content)

[Photosensitizer]

‧1,4-diethoxynaphthalene: 1 part by mass

(15) Preparation of retardation layer structure A with base material layer

On the surface of the first liquid crystal cured layer A (1/2 wavelength retardation layer) on the base layer, and the surface of the second liquid crystal cured layer A (1/4 wavelength retardation layer) on the base layer, the to corona treatment. The respective corona-treated surfaces were bonded together using the active energy ray-curable adhesive A prepared above so that the angle formed by the slow axes of the two retardation layers was 60°. Then, from the side of the 1/4 wavelength retardation layer, using an ultraviolet irradiation device [manufactured by FUSION UV SYSTEMS Co., Ltd.], ultraviolet irradiation was performed with a cumulative light amount of 400 mJ/cm ² (UV-B), and the active energy ray curing type was bonded. Agent A hardens to form an adhesive layer. The bonding was performed using a laminator, and the active energy ray-curable adhesive A was applied so that the thickness of the adhesive layer after curing was 3 μm. Thereby, the retardation layer structure A with a base material layer was obtained, in which "the base material layer, the alignment layer, the 1/2 wavelength retardation layer (the first liquid crystal cured layer), and the adhesive agent layer (the second bonding layer), 1/4 wavelength retardation layer (second liquid crystal cured layer), alignment layer, and base material layer". The total thickness of the 1/2 wavelength retardation layer (1st liquid crystal cured layer), the adhesive layer (2nd bonding layer), and the 1/4 wavelength retardation layer (2nd liquid crystal cured layer) was 6 μm .

(16) Preparation of the first liquid crystal cured layer B (1/4 wavelength retardation layer)

An alignment layer was formed on a base material layer formed of a transparent resin, and a liquid crystal layer-forming composition containing a rod-shaped nematic polymerizable liquid crystal compound was applied to prepare a first liquid crystal cured layer B. The first liquid crystal cured layer B has a 1/4 wavelength retardation characteristic. The thickness of the first liquid crystal cured layer B was 2 μm .

(17) Preparation of the second liquid crystal cured layer B (positive C layer)

10.0 parts by mass of polyethylene glycol di(meth)acrylate, 10.0 parts by mass of trimethylolpropane triacrylate, and 10.0 parts by mass of 1,6-hexanediol di(meth)acrylate were used as photopolymerization initiators. 9071.50 parts by mass of IRGACURE as the starting agent was dissolved in 70.0 parts by mass of methyl ethyl ketone which is a solvent to prepare a composition for forming an alignment layer. Next, 20.0 parts by mass of the photopolymerizable nematic liquid crystal compound was used as a photopolymerization initiator. 9071.0 parts by mass of IRGACURE was dissolved in 80.0 parts by mass of propylene glycol monomethyl ether acetate which is a solvent to prepare a composition for forming a liquid crystal layer.

Corona treatment is applied to one side of the substrate layer. On the corona-treated surface, the composition for forming an alignment layer prepared above was applied with a bar coater. After heat treatment at a temperature of 80° C. for 60 seconds was given to the coating layer, ultraviolet rays were irradiated to polymerize and harden the composition for forming an alignment layer. In this way, an alignment layer having a thickness of 2.2 μm was formed on the base material layer. On the alignment layer, the composition for forming a liquid crystal layer prepared as described above is applied. After heat treatment at a temperature of 80° C. for 60 seconds was given to the coating layer, ultraviolet rays were irradiated to polymerize and harden the composition for forming a liquid crystal layer. In this way, the second liquid crystal cured layer B with a thickness of 0.7 μm was formed on the alignment layer. The second liquid crystal cured layer B is a positive C layer.

(18) Preparation of Active Energy Ray Curable Adhesive B

The components shown below were mixed to prepare an active energy ray-curable adhesive B.

3,4-epoxycyclohexanecarboxylic acid 3',4'-epoxycyclohexylmethyl ester (trade name: CEL2021P, manufactured by DAICEL Co., Ltd.): 70 parts by mass

Neopentyl glycol diglycidyl ether (trade name: EX-211, manufactured by NAGASE CHEMTEX Co., Ltd.): 20 parts by mass

2-Ethylhexylglycidyl ether (trade name: EX-121, manufactured by NAGASE CHEMTEX Co., Ltd.): 10 parts by mass

Cationic polymerization initiator (trade name: CPI-100, 50% solution, manufactured by San-Apro Co., Ltd.): 4.5 parts by mass (substantial solid content 2.25 parts by mass)

1,4-diethoxynaphthalene: 2.0 parts by mass

(19) Preparation of retardation layer structure B with base material layer

The 1st liquid crystal hardening layer B and the 2nd liquid crystal hardening layer B were made to each liquid crystal hardening layer (the surface opposite to the base film) by the active energy ray hardening type adhesive B (thickness 1 μm ) Laminate in a way that becomes a bonding surface. The active energy ray-curable adhesive B is cured by irradiating ultraviolet rays, and a retardation layer structure B with a base material layer is obtained, in which "the base material layer, the alignment layer, the first liquid crystal cured layer B, and the adhesive agent layer are laminated in this order. (2nd bonding layer), 2nd liquid crystal cured layer B, alignment layer, and base material layer". The thickness of the retardation layered body including the first liquid crystal cured layer B, the adhesive layer (second bonding layer), and the second liquid crystal cured layer B is 6 μm . The retardation layer structure B with a base material layer has ultraviolet absorbability.

(20) Preparation of adhesive layer

Prepare the following adhesive layers.

Adhesive layer (1A): acrylic adhesive layer with a thickness of 5 μm

Adhesive layer (1B): acrylic adhesive layer with a thickness of 5 μm . Absorbs visible light with short wavelengths around 410nm.

Adhesive layer (2): Adhesive layer with a thickness of 15 μm

<The production of circular polarizer>

[Example 1]

The 1/2 wavelength retardation layer exposed by peeling off the base material layer and the orientation layer on the side of the 1/2 wavelength retardation layer of the retardation layer structure A with the base material layer prepared above, and the above prepared The protective film A side (surface of the hard coat layer) of the linear polarizer 1 is bonded using the adhesive layer (1A) belonging to the first bonding layer. The lamination of the 1/2 wavelength retardation layer and the linear polarizer 1 was performed so that the angle formed by the slow axis of the 1/2 wavelength retardation layer and the transmission axis of the polarizer 1 was 15°. Then, on the 1/4 wavelength retardation layer exposed by peeling off the alignment layer and the base material layer on the side of the 1/4 wavelength retardation layer, the adhesive layer (2) is bonded to obtain a circularly polarizing plate (1) . Corona treatment was performed on each bonding surface.

[Example 2]

It was obtained in the same manner as in Example 1, except that the corona treatment was not applied to the bonding surface of the protective film A of the linear polarizing plate 1 (the surface of the hard coat layer) and the bonding surface of the adhesive layer (1A). Circular polarizer (2).

[Example 3]

A circular polarizing plate ( 3 ) was obtained in the same manner as in Example 1 except that the linear polarizing plate 1 was used instead of the linear polarizing plate 1 .

[Example 4]

A circular polarizer ( 4 ) was obtained in the same manner as in Example 1, except that the linear polarizer 3 was used instead of the linear polarizer 1 .

[Example 5]

A circular polarizing plate ( 5 ) was obtained in the same manner as in Example 1 except that the linear polarizing plate 1 was used instead of the linear polarizing plate 1 .

[Example 6]

A circular polarizer ( 6 ) was obtained in the same manner as in Example 1, except that the linear polarizer 5 was used instead of the linear polarizer 1 .

[Example 7]

A circular polarizer ( 7 ) was obtained in the same manner as in Example 1 except that the linear polarizer 6 was used instead of the linear polarizer 1 .

[Example 8]

A circularly polarizing plate (8) was obtained in the same manner as in Example 1, except that the linear polarizing plate 6 was used instead of the linear polarizing plate 1, and the adhesive layer (1B) was used as the first bonding layer.

[Example 9]

A circular polarizing plate ( 9 ) was obtained in the same manner as in Example 1 except that the linear polarizing plate 1 was used instead of the linear polarizing plate 1 .

[Example 10]

A circular polarizing plate ( 10 ) was obtained in the same manner as in Example 1 except that the linear polarizing plate 1 was replaced with the linear polarizing plate 8 .

[Example 11]

The first liquid crystal cured layer B exposed by peeling off the base material layer on the side of the first liquid crystal cured layer B of the retardation layer structure B with the base material layer prepared above, and the linear polarizing plate 6 prepared above. The protective film C side is bonded using the adhesive layer (1A) belonging to the first bonding layer. The bonding of the first liquid crystal cured layer B and the linear polarizer 6 was performed so that the angle formed by the slow axis of the first liquid crystal cured layer B and the transmission axis of the polarizer 1 was 45°. Then, on the 2nd liquid crystal cured layer B which peeled and exposed the base material layer of the 2nd liquid crystal cured layer B side, the adhesive bond layer (2) was bonded together, and the circularly polarizing plate (11) was obtained. Corona treatment was performed on each bonding surface.

With respect to the obtained circularly polarizing plate, the above-mentioned heat resistance test, wet heat durability test, and weather resistance test were performed. The results are shown in Table 1.

[Table 1]

1: Circular polarizer

10: Linear polarizer

20: Retardation layer structure

30a: 1st bonding layer

Claims (9)

A circular polarizer, comprising: a linear polarizer and a liquid crystal hardening layer; Wherein, the linear polarizer includes a polarizer and a protective film that is only laminated on one side of the polarizer; Moreover, the said polarizer, the said protective film, and the said liquid crystal cured layer are arrange|positioned sequentially. The circularly polarizing plate according to claim 1, further comprising a hard coat layer between the protective film and the liquid crystal hardened layer. The circular polarizing plate according to claim 1 or 2, wherein the content of boron in the polarizer is 0.5 mass % or more and 5.5 mass % or less. The circularly polarizing plate according to any one of claims 1 to 3, wherein the protective film is a cyclic polyolefin-based resin film. The circularly polarizing plate according to any one of claims 1 to 4, wherein the liquid crystal cured layer includes a first liquid crystal cured layer and a second liquid crystal cured layer, and the polarizer, the protective film, and the first liquid crystal The cured layer and the aforementioned second liquid crystal cured layer are sequentially arranged. The circularly polarizing plate according to any one of claims 1 to 5, wherein any layer other than the aforementioned polarizer has light selective absorption. The circularly polarizing plate according to any one of Claims 1 to 6, comprising in this order: the polarizer, the protective film, the liquid crystal curing layer, and the adhesive layer. An optical laminate for a flexible image display device, comprising: the circularly polarizing plate according to any one of claims 1 to 7, and a front panel or a touch sensing panel. An image display device comprising: the circularly polarizing plate according to any one of claims 1 to 7, or the optical laminate according to claim 8.

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