TW202109159A - Circular polarizing plate and image display device - Google Patents

Abstract

An objective of the present invention is to provide a circular polarizing plate capable of constituting an image display device capable of suppressing the visual recognition of light of different colors depending on regions even when the image display device is visually recognized in a bent state.

As a solution, provided is a circular polarizing plate that can be folded and used, and has an antireflection layer, a linear polarizing plate, and a λ/4 retardation plate in this order; in the λ/4 retardation plate, when the in-plane retardation value at a wavelength of 550 nm is Re(550) [nm], Re(550) satisfies the relationship of formula (1a) or formula (2a).

141nm≦Re(550)≦180nm (1a)

95nm≦Re(550)≦134nm (2a)

Description

Circular polarizing plate and image display device

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

Organic EL display devices using organic light-emitting diodes (OLED) are used in various fields such as smart phones, televisions, and digital cameras. In addition, since the organic EL display device is thin and can display without using a backlight, there is known a device shape that is bent and curled. In the organic EL display device, in order to suppress the reduction of the recognition due to the reflection of external light, a circular polarizing plate is used to improve the anti-reflection performance.

For example, Patent Document 1 discloses a circular polarizing plate suitable for use in image display panels such as organic EL display devices.

[Prior Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2018-169508

When the image display device with the circular polarizing plate is recognized in the bent state, the light of different tones is recognized according to the area, which may cause poor recognition.

The object of the present invention is to provide a circularly polarizing plate and an image display device, which can be configured to suppress the recognition of different colors of light depending on the area even when the image display device is recognized in a bent state. Like a display device.

The present invention provides the circular polarizing plate and image display device described below.

[1] A circular polarizing plate, which can be bent for users, and has in order:

Anti-reflection layer, linear polarizing plate, and λ/4 retardation plate; among them,

The aforementioned λ/4 retardation plate system: When the in-plane retardation value at a wavelength of 550 nm is set to Re(550) [nm], Re(550) satisfies the relationship of formula (1a) or formula (2a).

141nm≦Re(550)≦180nm (1a)

95nm≦Re(550)≦134nm (2a)

[2] A circular polarizing plate that can be bent along the bending centerline, and has in order:

Anti-reflection layer, linear polarizing plate, and λ/4 retardation plate; among them,

The aforementioned λ/4 retardation plate system: when the in-plane retardation value at a wavelength of 550nm is set to Re(550)[nm], Re(550) satisfies the relationship of formula (1b) or formula (2b),

138nm≦Re(550)<141nm (1b)

134nm<Re(550)≦137nm (2b)

The slow axis of the aforementioned λ/4 retardation plate is bent and used so that the included angle with the aforementioned bending center line becomes 70° or less.

[3] The circularly polarizing plate according to [1] or [2], wherein the λ/4 retardation plate has reverse wavelength dispersion.

[4] The circularly polarizing plate according to any one of [1] to [3], wherein the λ/4 retardation plate has a retardation expression layer containing a cured product of a polymerizable liquid crystal compound.

[5] The circular polarizing plate according to [4], wherein the thickness of the retardation expression layer is 0.5 μm or more and 10 μm or less.

[6] A circular polarizing plate with a front panel, comprising the circular polarizing plate described in any one of [1] to [5], and a front panel.

[7] A circular polarizing plate with a touch sensor panel, comprising the circular polarizing plate described in any one of [1] to [5], and a touch sensor panel.

[8] An image display device comprising an image display panel, and a circular polarizing plate as described in any one of [1] to [5] arranged on the front side of the image display panel, or as [ 6] The circular polarizing plate with front panel, or the circular polarizing plate as described in [7].

[9] The image display device according to [8], wherein the image display panel is an organic electroluminescence display panel.

With the image display device having the circular polarizing plate of the present invention, even if it is recognized in a bent state, it is possible to suppress the recognition of light of different tones depending on the area.

10: Circular polarizing plate

11: λ/4 phase difference plate

13: Linear polarizer

16: Laminated layer

19: Anti-reflective layer

20: Image display device

30: Image display panel

40: Test sample

41: reflector

42: Test strip

50: Spectrophotometer

111: substrate layer

112: Orientation layer

113: retardation layer

114: substrate layer

115: Laminated layer

Fig. 1 is a schematic cross-sectional view schematically showing an example of the circular polarizing plate of the present invention.

Fig. 2 is a schematic cross-sectional view schematically showing an example of the image display device of the present invention.

Fig. 3 is a schematic cross-sectional view schematically showing an example of the λ/4 retardation plate of the present invention.

Fig. 4 is a schematic cross-sectional view schematically showing another example of the λ/4 retardation plate of the present invention.

Fig. 5 is a diagram schematically showing the measurement samples in Test Examples A and B.

Fig. 6 is a schematic diagram showing the positional relationship between the measurement sample ((a) flat state, (b) bent state) and the spectrophotometer in the measuring device in Test Examples A and B.

The following describes the embodiments of the present invention while referring to the drawings, but the present invention is not limited to the following embodiments. In all the following drawings, in order to make the constituent elements easy to understand, the size ratios are appropriately adjusted and displayed. The proportions of the constituent elements shown in the drawings may not be the same as the actual ratios of the constituent elements.

〔Circular Polarizing Plate〕

FIG. 1 is a schematic cross-sectional view schematically showing an example of the circular polarizing plate 10 of this embodiment. As shown in FIG. 1, the circular polarizing plate 10 has an anti-reflection layer 19, a linear polarizing plate 13, a bonding layer 16, and a λ/4 retardation plate 11 in this order from the front side. In the circular polarizing plate 10, the linear polarizing plate 13 and the λ/4 retardation plate 11 may be laminated without interposing the bonding layer 16 therebetween. The circular polarizing plate 10 is a circular polarizing plate that can be bent for use. The circularly polarizing plate 10 preferably has a bending centerline in the direction orthogonal to the stacking direction. As the bending type, it is exemplified: the bending type in which the area including the bending centerline becomes a curved surface, and the bending centerline Set as a zigzag pattern where the boundary makes two planes close to each other.

[Image display device]

FIG. 2 is a schematic cross-sectional view schematically showing an example of the image display device 20 of this embodiment. As shown in FIG. 2, the image display device 20 has the circular polarizing plate 10 and the image display panel 30 shown in FIG. 1 in order from the front side. In the image display device 20, the circularly polarizing plate 10 is arranged such that the anti-reflection layer 19 side faces the front side.

In the image display device 20, light incident from the outside includes light reflected by the circular polarizing plate 10 and light transmitted through the circular polarizing plate 10. The light reflected by the surface of the circular polarizer 10 (hereinafter also referred to as “external reflected light”) is sufficiently reduced by the anti-reflection layer 19. The light passing through the circular polarizing plate 10 is reflected by the image display panel 30 to become reflected light (hereinafter also referred to as “internally reflected light”) and is absorbed by the circular polarizing plate 10. Although it is desired that all the internally reflected light is absorbed by the circular polarizing plate 10, a part of it is emitted from the front surface (hereinafter, this light is also referred to as "emitting internally reflected light").

Since the image display device 20 suppresses external reflected light by the anti-reflection layer 19, compared with the configuration without the anti-reflection layer 19, it has a configuration that emits internal reflection light and is easy to recognize.

The image display device 20 is a flexible display, which is an image display device that is identifiable in a bent state along the bending center line orthogonal to the stacking direction. In the image display device 20, the bending center line is an imaginary line that becomes the center of the assumed bending in the use state, for example, on the front surface of the image display device 20. The position of the bending center line on the front side can be adjusted by the desired design, but usually passes through the center of the front side. The bending center line is usually a straight line.

The image display device 20 may be used by bending the front side toward the inner side and along the bending center line, or may be used by bending the front side toward the outer side and along the bending center line. The image display device 20 may be configured to bend only the front side toward the inside, may be configured to bend only the front side toward the outside, or may be configured to bend the front side toward the inside or outside.

In this specification, bending includes: the bending type in which the area including the bending center line becomes a curved surface, and the zigzag type in which the bending center line is set as the boundary so that the two planes are close to each other. An example of the bending pattern in which the area including the bending centerline becomes a curved surface: the radius of curvature of the central area including the bending centerline is the smallest and gradually increases from the bending centerline to the radius of curvature along the away direction Bending type; only the central area including the bending centerline becomes a curved surface, while other areas maintain the flat bending type, etc. In the bending type in which the area including the bending center line becomes a curved surface, the radius of curvature is not particularly limited. For the zigzag type in which the bending center line is set as the boundary so that the two planes are close to each other, the zigzag angle of the inner surface is not particularly limited, and it is greater than 0 degrees and less than 180 degrees. The tortuous angle is, for example, greater than 30 degrees and less than 180 degrees.

When the image display device 20 is bent along the bending centerline for use, the circular polarizer 10 assembled in the image display device 20 is also bent along the bending centerline of the image display device 20 for use.

<λ/4 retardation plate>

The λ/4 retardation plate 11 substantially has a function of imparting a λ/4 phase difference to incident light. λ/4 retardation plate 11 series: When the in-plane retardation value at a wavelength of 550nm is set to Re(550)[nm], Re(550) meets the relationship of formula (1) or formula (2),

138nm≦Re(550)≦180nm (1)

95nm≦Re(550)≦137nm (2).

The λ/4 retardation plate 11 is divided into a case where Re (550) satisfies the formula (1), a case satisfies the formula (1a), and a case satisfies the formula (1b).

141nm≦Re(550)≦180nm (1a)

138nm≦Re(550)<141nm (1b)

The λ/4 retardation plate 11 is divided into a case where Re (550) satisfies the formula (2), a case satisfies the formula (2a), and a case satisfies the formula (2b).

95nm≦Re(550)≦134nm (2a)

134nm<Re(550)≦137nm (2b)

When Re (550) satisfies the formula (1a), in the circular polarizer 10, from the viewpoint that the tone of the emitted internal reflection light is close to neutral, the λ/4 retardation plate 11 preferably satisfies Formula (1a'), more preferably satisfies formula (1a").

141nm≦Re(550)≦150nm (1a’)

141nm≦Re(550)≦145nm (1a”)

When Re (550) satisfies the formula (2a), in the circular polarizer 10, from the viewpoint that the tone of the emitted internal reflection light is close to neutral, the λ/4 retardation plate 11 preferably satisfies the formula (2a '), the better system satisfies the formula (2a").

125nm≦Re(550)≦134nm (2a’)

125nm≦Re(550)≦130nm (2a”)

The λ/4 retardation plate 11 is a layer in which Re(λ) belonging to the in-plane retardation value in the specific wavelength λnm satisfies Re(λ)=λ/4, as long as it can be achieved at any wavelength in the visible light domain. When designing the way to achieve 550nm, it becomes Re(550)=137.5nm. The inventors found that when the display device designed in this way is recognized in the bent state, the color tone of the light emitted from the area near the bending center line is different from the color tone of the light emitted from other areas, and the recognition is possible. Will decrease. Then, it was found that the circularly polarizing plate provided on the front side of the image display element of the image display device has an anti-reflective layer on the front surface, and the reduction in recognition is more significant.

Based on the above findings, it can be inferred that the mechanism of the failure is as follows. When the image display device 20 with a circular polarizing plate arranged on the front surface (single side) of the image display panel is in a planar state, the λ/4 retardation plate 11 constituting the circular polarizing plate 10 is Re(550)=137.5nm At this time, the hue of the internal reflected light is neutral (colorless) in the flat state. However, when the image display device 20 is bent so that the front side (outer side) becomes a convex surface, the stretching force is applied to the vicinity of the bending center line of the circular polarizing plate 10 arranged on the front side (outer side). The extension force is also applied to the λ/4 retardation plate 11 constituting the circular polarizing plate 10. The extension force increases the in-plane retardation of the λ/4 retardation plate 11. As a result, the hue of the emitted internal reflected light is slightly shifted to the blue side. Therefore, the hue of the internally reflected light that is close to neutral in the planar state is biased toward blue.

On the other hand, in the portion away from the bending center line, the extension force is not applied to the circular polarizing plate 10. There is no slight change in the in-plane phase difference. The hue of the internal reflected light is not slightly shifted to the blue side, and it remains neutral. Therefore, the hue that emits internal reflected light tends to be blue on the bending center line. On the other hand, the part away from the bending center line remains neutral and this part is recognized as a color spot.

Next, when the image display device 20 is bent so that the front side (outside) becomes a concave surface, compressive force is applied to the circular polarizing plate 10 (and the λ/4 retardation plate 11) arranged on the front side (outside) ). The compressive force slightly reduces the in-plane retardation of the λ/4 retardation plate 11. As a result, the hue of the emitted internal reflected light is slightly shifted to the red side. On the other hand, in the part away from the bending center line, since the neutral is maintained, the color spot is recognized.

Let the in-plane retardation in the wavelength 450nm of the λ/4 retardation plate 11 be Re(450)[nm], and the in-plane retardation in the wavelength 650nm as Re(650)[nm],

α=Re(450)/Re(550) The α value shown is usually 0.81 to 0.92, preferably 0.81 to 0.88, ideally 450/550 (=0.82),

The β value shown by β=Re(650)/Re(550) is usually 0.99 to 1.20, preferably 1.01 to 1.19, ideally 650/550 (=1.18). By designing in this way, in the wide wavelength range of 450 to 650nm, although the hue of the internal reflected light that functions as a λ/4 retardation plate in the planar state becomes more neutral, the color spot becomes more neutral. obvious.

In the present invention, the in-plane phase difference Re (550) is set to a slightly larger value (138 nm or more, and the formula (1) is satisfied) in advance. As a result, in the flat state, it becomes a state slightly biased to the blue side in advance. Even if an extension force is applied to bend so as to become convex from then and to be more toward the blue side, since the hue has been slightly shifted to the blue side in advance, the hue change is not obvious. Even if a compressive force is applied to bend so as to become a concave surface and the hue is biased toward the red side, since the hue does not reach neutral (colorless) and it becomes light blue, the hue change is not obvious in this case.

In the present invention, the in-plane phase difference Re (550) is set to a slightly smaller value (137 nm or less and satisfies the formula (2)) in advance. As a result, in the planar state, it becomes a state slightly biased to the red side in advance. Even if an extension force is applied to bend so as to become a convex surface from now on and bend to the red side, since it will not be neutral (colorless), and it will become light red, so the color spots are not obvious. Even if a compressive force is applied to bend so as to become a concave surface and deviate toward the red side, since the hue is slightly toward the red side in advance, the change is not noticeable.

In the case where the in-plane retardation value Re(550) satisfies the relationship of equation (1b) or equation (2b), since there is an effect of not being able to sufficiently suppress the recognition of different tones of light depending on the region, except for the in-plane retardation value In addition to the design of Re (550), it is preferable that the angle θ [°] between the bending center line of the circular polarizer 10 and the slow axis of the λ/4 retardation plate 11 is 70° or less. Accordingly, It is inferred that even if the λ/4 retardation plate 11 receives force due to bending, it is possible to suppress the amount of change in the in-plane retardation value by adjusting the angle between the force direction and the slow axis. The angle θ satisfies the formula (4a), preferably satisfies the formula (4b).

0°≦θ≦70° (4a)

0°≦θ≦50° (4b)

In addition, even if the in-plane retardation value Re (550) of the λ/4 retardation plate 11 satisfies the relationship of the equation (1a) or the equation (2a), the difference in the color tone of the emitted internal reflected light is suppressed depending on the area From a standpoint, the angle θ preferably satisfies the formula (4a), and more preferably satisfies the formula (4b).

The λ/4 retardation plate 11 may include a retardation expression layer expressing a retardation, may be composed of only the retardation expression layer, or may include another layer at the same time as the retardation expression layer. Examples of other layers include a substrate layer, an alignment film layer, and a protective layer. In addition, other layers will not affect the value of the retardation. In this specification, the in-plane retardation value of the retardation expression layer contained in the λ/4 retardation plate 11 is the same as the in-plane retardation value of the retardation expression layer of the λ/4 retardation plate 11.

As the retardation expression layer, a liquid crystal layer containing a cured product of a polymerizable liquid crystal compound or a stretched film can be mentioned. The phase difference expression layer is preferably a liquid crystal layer from the viewpoint of making the polarizing plate composite thinner. In addition, in the circularly polarizing plate provided with the λ/4 retardation plate 11 having the retardation expression layer belonging to the liquid crystal layer, although the retardation change due to bending is large and the color difference is likely to occur, according to the present invention, Even in the case where the phase difference expression layer is a liquid crystal layer, it is possible to suppress the occurrence of a color tone difference during recognition in a bent state.

The thickness of the retardation expression layer is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 5 μm. In addition, the λ/4 retardation plate 32 includes layers other than the retardation expression layer (base material layer, In the case of an alignment film layer, a protective layer, etc.), the overall thickness is preferably 0.5 μm to 300 μm, more preferably 0.5 μm to 150 μm.

The optical characteristics of the λ/4 retardation plate 11 can be adjusted by the alignment state of the liquid crystal compound constituting the retardation display layer or the stretching method of the stretched film constituting the retardation display layer.

Although the λ/4 retardation plate 11 can be a positive wavelength dispersion retardation plate or a reverse wavelength dispersion retardation plate, from the viewpoint of exhibiting anti-reflection function for a wide band of wavelengths, reverse wavelength dispersion is preferred. Sexual phase difference board. Inverse wavelength dispersion means an optical characteristic in which the in-plane retardation value of the short wavelength is smaller than the in-plane retardation value of the long wavelength, and preferably satisfies the following formula (5).

Re(450)≦Re(550)≦Re(650) (5)

(1) When the phase difference expression layer is a liquid crystal layer

The case where the retardation expression layer is a liquid crystal layer will be described. FIG. 3 is a schematic cross-sectional view schematically showing an example of a λ/4 retardation plate including a retardation expression layer belonging to a liquid crystal layer and other layers. The λ/4 retardation plate 11 shown in FIG. 3 is laminated with a substrate layer 111, an alignment layer 112, and a liquid crystal layer, that is, a retardation expression layer 113 in this order. The λ/4 retardation plate 11 is not limited to the configuration shown in FIG. 3 as long as it includes the retardation expression layer 113 belonging to the liquid crystal layer, and may be the alignment layer 112 and the retardation that are only peeled off from the base layer 111 The structure of the expression layer 113 may also be a structure composed of only the phase difference expression layer 113 of the liquid crystal layer from which the base layer 111 and the alignment layer 112 are peeled off.

4 is a schematic cross-sectional view schematically showing another example of a phase difference body including a liquid crystal layer, that is, a phase difference layer and other layers. The λ/4 retardation plate 11 shown in FIG. 4 is laminated with a base layer 114, a bonding layer 115, and a retardation expression layer 113 in this order. The λ/4 retardation plate 11 is shown in FIG. 3, the retardation expression layer 113 of the λ/4 retardation plate 11 and the other base material layer 114 The bonding layer 115 is bonded, and thereafter, the base layer 111 or the base layer 111 and the alignment layer 112 are peeled off to form. Examples of the bonding layer 115 include an adhesive layer and an adhesive layer.

The base layer 111 has a function as a support layer to support the alignment layer 112 formed on the base layer 111 and the liquid crystal layer, that is, the phase difference expression layer 113. The base layer 111 is preferably a film formed of a resin material.

As the resin material of the base layer 111, for example, resin materials excellent in transparency, mechanical strength, thermal stability, and extensibility can be used. Specifically, examples include polyolefin-based resins such as polyethylene and polypropylene; cyclic polyolefin-based resins such as norbornene-based polymers; polyesters such as polyethylene terephthalate and polyethylene naphthalate Series resins; (meth)acrylic resins such as (meth)acrylic acid and polymethyl (meth)acrylate; cellulose ester resins such as cellulose triacetate, cellulose diacetate, and cellulose acetate propionate; polyethylene Vinyl alcohol-based resins such as alcohols and polyvinyl acetate; polycarbonate-based resins; polystyrene-based resins; polyarylate-based resins; polyether-based resins; polyether-based resins; polyamide-based resins; polyamides Amine resins; polyetherketone resins; polyphenylene sulfide resins; polyphenylene ether resins, and mixtures and copolymers thereof. Among these resins, it is preferable to use any one of a cyclic polyolefin resin, a polyester resin, a cellulose ester resin, and a (meth)acrylic resin, or a mixture thereof. In addition, the above-mentioned "(meth)acrylic acid" means "at least one of acrylic acid and methacrylic acid".

The base material layer 111 may be a single layer in which one or two or more of the above-mentioned resins are mixed, or may have a multiple-layer structure having two or more layers.

Any additives can be added to the resin material forming the resin film. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, coloring inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, and coloring agents.

The thickness of the base layer 111 is not particularly limited, but generally, from the viewpoint of workability such as strength and handling properties, it is preferably 5 to 200 μm, more preferably 10 to 200 μm, and still more preferably 10 to 150 μm.

In order to improve the adhesion between the substrate layer 111 and the alignment layer 112, corona treatment, plasma treatment, flame treatment, etc. can be performed on at least the surface of the substrate layer 111 on the side where the alignment layer 112 is formed. Paint layer and so on. In addition, in the case where the base layer 111 or the base layer 111 and the alignment layer 112 are peeled off to be a retardation layer, the adhesion of the peeling interface can be adjusted to facilitate peeling. Regarding the material, thickness, and treatment of the base layer 114, the description applies to the base layer 111.

The alignment layer 112 has an alignment control force that aligns the liquid crystal compound contained in the phase difference expression layer 113 of the liquid crystal layer formed on the alignment layer 112 to a desired direction. Examples of the alignment layer 112 include: an alignment polymer layer formed of an alignment polymer, a photo-alignment polymer layer formed of a photo-alignment polymer, and a concave-convex pattern and a plurality of grooves on the surface of the layer.的槽Alignment layer. The thickness of the alignment layer 112 is usually 0.01 to 10 μm, preferably 0.01 to 5 μm.

The aligning polymer layer can be formed by coating a composition in which the aligning polymer is dissolved in a solvent on the base layer 111, removing the solvent, and performing rubbing as needed. At this time, in the alignment polymer layer formed of the alignment polymer, the alignment control force can be arbitrarily adjusted according to the surface state of the alignment polymer and the friction conditions.

The photo-alignment polymer layer can be formed by coating a composition containing a polymer or monomer having a photoreactive group and a solvent on the substrate layer 111 and irradiating it with polarized light. At this time, in the photo-alignment polymer layer, the alignment control force can be arbitrarily adjusted according to the polarized light irradiation conditions for the photo-alignment polymer.

The groove alignment layer can be formed by the following methods, for example: a method of forming a concave-convex pattern on the surface of the photosensitive polyimide film through an exposure mask having a slit in a pattern shape, and then performing exposure and development; A method of forming an uncured layer of active energy ray curable resin on a plate-shaped master with grooves, transferring the layer to the base layer 111 and curing; forming an active energy ray curable resin on the base layer 111 For the uncured layer, a method of forming unevenness on the layer by pressing a roller-shaped master plate with unevenness and hardening.

The phase difference expression layer 113 belonging to the liquid crystal layer can be formed using a conventional liquid crystal compound. The type of liquid crystal compound is not particularly limited, and rod-shaped liquid crystal compounds, disc-shaped liquid crystal compounds, and mixtures thereof can be used. In addition, the liquid crystal compound may be a polymer liquid crystal compound, may be a polymerizable liquid crystal compound, or a mixture thereof. As the liquid crystal compound, for example, Japanese Patent Application Publication No. 11-513019, Japanese Patent Application Publication No. 2005-289980, Japanese Patent Application Publication No. 2007-108732, Japanese Patent Application Publication No. 2010-244038, Japanese Patent Application Publication No. 2010- 31223, Japanese Patent Application Publication No. 2010-270108, Japanese Patent Application Publication No. 2011-6360, Japanese Patent Application Publication No. 2011-207765, Japanese Patent Application Publication No. 2016-81035, International Publication No. 2017/043438, and Japanese Patent Application Publication No. Table 2011-207765 The liquid crystal compounds described in the publication.

For example, in the case of using a polymerizable liquid crystal compound, a composition containing the polymerizable liquid crystal compound can be coated on the alignment layer 112 to form a coating film, and the coating film can be cured to form the retardation expression layer 113. The retardation expression layer 113 formed in this way becomes a cured product containing a polymerizable liquid crystal compound. The thickness of the retardation expression layer 113 is preferably 0.5 μm to 10 μm, more preferably 0.5 to 5 μm.

The composition containing the polymerizable liquid crystal compound may contain polymerization initiators, polymerizable monomers, surfactants, solvents, tackifiers, plasticizers, alignment agents, etc. in addition to the liquid crystal compounds. As a coating method of the composition containing a polymerizable liquid crystal compound, conventional methods, such as a die-casting die coating method, are mentioned. Examples of the curing method of the composition containing the polymerizable liquid crystal compound include conventional methods such as irradiation with active energy rays (for example, ultraviolet rays).

(2) Stretched film, that is, retardation display layer

The case where the retardation expression layer is a stretched film will be described. The stretched film is usually obtained by stretching the substrate. The method of stretching the base material includes, for example, preparing a roll (winding body) that winds the base material on a roll, continuously winding the base material from the winding body, and transporting the wound base material to a heating furnace. method. The setting temperature of the heating furnace is set in the range from around the glass transition temperature of the substrate (℃) to [glass transition temperature + 100] (℃), preferably around the glass transition temperature (℃) to [glass transition temperature + 50 ] (℃) range. In this heating furnace, when extending in the direction of progress of the base material or in the direction orthogonal to the direction of progress, the conveying direction and tension are adjusted and tilted at an arbitrary angle to perform uniaxial or biaxial heat stretching. The extension magnification is usually 1.1 to 6 times, preferably 1.1 to 3.5 times.

In addition, as a method of extending in the oblique direction, there is no particular limitation as long as the alignment axis can be continuously tilted to a desired angle, and a conventional extending method can be adopted. Examples of such extension methods include methods described in Japanese Patent Application Laid-Open No. 50-83482 and Japanese Patent Application Laid-Open No. 2-113920. In the case of imparting retardation to the film by stretching, the thickness after stretching depends on the thickness before stretching and the stretching magnification.

The aforementioned substrate is usually a transparent substrate. The transparent substrate refers to a substrate having transparency that can transmit light, especially visible light, and transparency refers to the characteristic that the transmittance of light with a wavelength of 380 to 780 nm is more than 80%. As a specific transparent substrate, light transmittance can be cited Resin substrate. Examples of resins constituting the light-transmitting resin substrate include polyolefins such as polyethylene and polypropylene; cyclic olefin-based resins such as norbornene-based polymers; polyvinyl alcohol; polyethylene terephthalate; -Based acrylate; polyacrylate; cellulose triacetate, cellulose diacetate, cellulose acetate propionate and other cellulose esters; polyethylene naphthalate; polycarbonate; ; Polyphenylene sulfide and polyphenylene ether. From the viewpoints of easy availability and transparency, polyethylene terephthalate, polymethacrylate, cellulose ester, cyclic olefin resin, or polycarbonate is preferred.

A part or all of the hydroxyl groups contained in the cellulose ester-based cellulose are esterified, which is easily available on the market. In addition, cellulose ester substrates are also easily available on the market. Examples of commercially available cellulose ester substrates include "FUJITAC (registered trademark) film" (Fuji Film (stock)); "KC8UX2M", "KC8UY", and "KC4UY" (KONICA MINOLTA (stock)).

Polymethacrylate and polyacrylate (hereinafter, polymethacrylate and polyacrylate may be collectively referred to as (meth)acrylic resin) are easily available on the market.

Examples of (meth)acrylic resins include homopolymers of alkyl methacrylate or alkyl acrylate, copolymers of alkyl methacrylate and alkyl acrylate, and the like. As the alkyl methacrylate, specifically, methyl methacrylate, ethyl methacrylate, propyl methacrylate, etc. can be cited, and as the alkyl acrylate, specifically, methyl acrylate can be cited. Ester, ethyl acrylate, propyl acrylate, etc. Among the (meth)acrylic resins, commercially available general-purpose (meth)acrylic resins can be used. As the (meth)acrylic resin, what is called an impact-resistant (meth)acrylic resin can also be used.

Furthermore, in order to further improve the mechanical strength, it is preferable to include rubber particles in a (meth)acrylic resin. The rubber particles are preferably acrylic. Here, the acrylic rubber particles mean: using an alkyl acrylate such as butyl acrylate or 2-ethylhexyl acrylate as the main component It is a particle with rubber elasticity obtained by polymerizing different acrylic monomers in the presence of a multifunctional monomer. The acrylic rubber particles may be formed of a single layer of particles having such rubber elasticity, or may be a multilayer structure having at least one layer of rubber elasticity. Examples of acrylic rubber particles with a multi-layer structure include: a particle having rubber elasticity as described above as a core, and a hard alkyl methacrylate polymer covering its surroundings; a hard alkyl methacrylate The base ester polymer is used as the core, and the surrounding area is covered with an acrylic polymer having rubber elasticity as described above; or the periphery of the hard core is covered with a rubber elastic acrylic polymer, and further with a hard armor Alkyl acrylate-based polymer coats its surroundings and the like. The rubber particles formed by the elastic layer generally have an average diameter in the range of about 50 to 400 nm.

The content of rubber particles in the (meth)acrylic resin is usually about 5 to 50 parts by mass per 100 parts by mass of the (meth)acrylic resin. Since (meth)acrylic resin and acrylic rubber particles are sold in a state where these raw materials are mixed, their commercially available products can be used. Examples of commercially available products of (meth)acrylic resin prepared with acrylic rubber particles include "HT55X" and "TECHNOLLOY S001" sold by Sumitomo Chemical Co., Ltd. and the like. "TECHNOLLOY S001" is sold as a film.

Cyclic olefin resins are easily available on the market. Examples of commercially available cyclic olefin resins include: "Topas" (registered trademark) [Ticona Corporation (Germany)], "ARTON" (registered trademark) [JSR (shares)], "ZEONOR" (registered trademark) [ Japan ZEON (stock)], "ZEONEX" (registered trademark) [Japan ZEON (stock)] and "APEL" (registered trademark) [Mitsui Chemicals (stock)]. Such a cyclic olefin-based resin can be used as a substrate by forming a film by a conventional method such as a solution casting method and a hot melt extrusion method. In addition, a commercially available cyclic olefin-based resin substrate may also be used. Examples of commercially available cyclic olefin resin substrates include: "ESCENA" (registered trademark) [Sekisui Chemical Industry Co., Ltd.], "SCA40" (registered trademark) [Sekisui Chemical Industry Co., Ltd.], "ZEONOR film" (registered trademark) [OPTES (share)] and "ARTON film" (registered trademark) [JSR (share)].

When the cyclic olefin resin is a copolymer of a cyclic olefin, a chain olefin or an aromatic compound having a vinyl group, the content ratio of the structural unit derived from the cyclic olefin is relative to the total structural unit of the copolymer , Usually less than 50 mol%, preferably in the range of 15 to 50 mol%. Examples of chain olefins include ethylene and propylene, and examples of aromatic compounds having vinyl groups include styrene, α-methylstyrene, and alkyl-substituted styrene. When the cyclic olefin resin is a terpolymer of a cyclic olefin, a chain olefin, and an aromatic compound with a vinyl group, the content ratio of the structural unit derived from the chain olefin is relative to the total copolymer The structural unit is usually 5 to 80 mol%, and the content ratio of the structural unit derived from the aromatic compound having a vinyl group is usually 5 to 80 mol% relative to the total structural unit of the copolymer. Such a terpolymer has the advantage that the amount of high-priced cyclic olefin used in its manufacture can be relatively small.

<Straight Polarizing Plate>

The linear polarizing plate 13 may be a film having a polarization function of obtaining linear polarization by transmitting light. Examples of the film include a stretched film to which a dye having absorption anisotropy is adsorbed, or a film including a film coated with a dye having absorption anisotropy as a polarizer, and the like. Examples of dyes having absorption anisotropy include dichroic dyes. A film that is used as a polarizer and coated with a dye having absorption anisotropy includes a stretched film that adsorbs a dye having absorption anisotropy, or coating a composition containing a dichroic dye having liquid crystallinity Or a composition containing a dichroic dye and a polymerizable liquid crystal to obtain a film having a liquid phase layer, etc.

(Linear polarizer with stretch film as polarizer)

Here, a description will be given of a linear polarizing plate provided with a stretched film to which a dye having absorption anisotropy is adsorbed as a polarizer. The stretched film that belongs to the polarizer and adsorbs the dye with absorption anisotropy usually has the following: the step of uniaxially stretching the polyvinyl alcohol-based resin film, and the polyvinyl alcohol-based resin film is dichroic dye It is produced by the steps of dyeing and adsorbing the dichroic pigment, the step of treating the polyvinyl alcohol resin film with the dichroic pigment adsorbed with the boric acid aqueous solution, and the step of washing with the boric acid aqueous solution after treatment. The polarizer can be used directly as a linear polarizer, or a transparent protective film can be attached to at least one side of the polarizer as a linear polarizer.

Thereby, the thickness of the polarizer obtained by uniaxial stretching, dichroic dye dyeing, boric acid treatment, water washing, and drying on the polyvinyl alcohol-based resin film is preferably 5 to 40 μm.

The material of the single-sided or double-sided protective film attached to the polarizer is not particularly limited, but examples include cyclic polyolefin resin films; such as cellulose triacetate and cellulose diacetate resins. Cellulose acetate resin film made up; such as polyester resin film made of resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate resin Films, (meth)acrylic resin films, polypropylene resin films, etc., are known in the art. The thickness of the protective film is generally 300 μm or less, preferably 200 μm or less, more preferably 50 μm or less from the viewpoint of thinning, and is usually 5 μm or more, preferably 20 μm or more. In addition, the protective film on the identification side may or may not have a phase difference. On the other hand, the protective film laminated on the side of the 1/2-wavelength layer 11 preferably has a retardation of 10 nm or less.

(Linear polarizing plate equipped with a film with a liquid crystal layer as a polarizer)

The linear polarizing plate provided with the film which has a liquid crystal layer as a polarizer is demonstrated. The film used as a polarizer and coated with a pigment with absorption anisotropy can include: coating contains A composition of a liquid crystal dichroic dye, a film obtained from a composition containing a dichroic dye and a liquid crystal compound, or the like. The film can be used as a linear polarizer alone, or as a linear polarizer with a protective film on one or both sides. As this protective film, the same thing as the linear polarizing plate provided with the said stretched film as a polarizer is mentioned.

The film coated with the pigment with absorption anisotropy is preferably thinner, but if it is too thin, the strength will decrease and the processability tends to be poor. The thickness of the film is usually 20 μm or less, preferably 5 μm or less, more preferably 0.5 μm or more and 3 μm or less.

The above-mentioned film coated with a dye having absorption anisotropy, specifically, a film described in JP 2013-33249 A and the like can be cited.

The aforementioned pigment with absorption anisotropy can be directly coated on the 1/2-wavelength layer 11 to form a polarizing plate composite. At this time, the second adhesive layer 22 does not need to be provided.

<Anti-reflective layer>

The anti-reflection layer 19 has a function of absorbing light reflected from the surface or inside of the circular polarizing plate 10, and can be formed by a conventional anti-reflection layer and the like, that is, a coating method or a sputtering method. , Vacuum deposition method and so on. The anti-reflection layer 19 is formed in advance on the front side of the protective film provided on the front side of the linear polarizing plate 13, and can constitute a linear polarizing plate with an anti-reflection layer using the protective film. After the plate 13 or after the linear polarizing plate 13 and the λ/4 retardation plate 11 are laminated, they are formed in front of the linear polarizing plate 13.

<Lamination layer>

The bonding layer 16 is an adhesive layer formed using an adhesive composition, or an adhesive layer formed using an adhesive composition.

The bonding layer 16 is a layer for bonding the λ/4 retardation plate 11 to other layers, and it can be directly disposed on the λ/4 retardation plate 11 or on the λ/4 retardation plate 11 And there is no need to interpose other bonding layer layers (alignment layer, base material layer used for forming the λ/4 retardation plate 11, etc.). The bonding layer 16 is an adhesive layer formed using an adhesive composition or an adhesive layer formed using an adhesive composition.

When the bonding layer 16 is an adhesive layer, as an adhesive composition used for forming an adhesive layer, as long as it can satisfy the said moisture permeability, it will not specifically limit. As the adhesive composition, as long as it contains, for example, rubber polymer, (meth)acrylic polymer, urethane polymer, polyester polymer, silicone polymer, polyvinyl ether polymer Polymers, polyvinyl alcohol-based polymers, polyolefin-based polymers, vinyl alkyl ether-based polymers, polyvinylpyrrolidone-based polymers, poly(meth)acrylamide-based polymers, cellulose-based polymers, etc. Whatever is the main component. In this specification, the main component means a component containing 50% by mass or more of the total solid content of the adhesive composition. The adhesive composition can be an active energy ray hardening type or a heat hardening type. As the adhesive composition, a rubber-based polymer is preferred. In addition, the above-mentioned "(meth)acrylic acid" means "at least one of acrylic acid and methacrylic acid". The description of "(meth)acrylate" etc. is also the same.

Examples of rubber-based polymers include: natural rubber; polyisobutylene rubber (PIB), isoprene rubber (IR), isobutylene-isoprene rubber (IIR), n-butylene-isobutylene copolymer rubber, butadiene rubber Ethylene rubber (BR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), benzene Ethylene-isoprene-styrene block copolymer rubber (SIBS), styrene-ethylene-butylene-styrene block copolymer rubber (SEBS), styrene-ethylene-propylene-styrene block copolymer Rubber (SEPS), styrene-butadiene Synthetic rubbers such as ethylene-styrene block copolymer rubber (SBS), styrene-ethylene-propylene block copolymer rubber (SEP), etc. The rubber polymer is preferably polyisobutylene rubber (PIB), isobutylene-isoprene rubber (IIR), n-butylene-isobutylene copolymer rubber, and more preferably polyisobutylene rubber (PIB).

As the (meth)acrylic polymer, butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate are suitably used. One or two or more types of (meth)acrylates are polymers or copolymers as monomers. Preferably, the polar monomer is copolymerized with the base polymer. Examples of polar monomers include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, (meth)acrylic acid N, A monomer having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, etc., of N-dimethylaminoethyl and glycidyl (meth)acrylate.

Active energy ray hardening adhesive composition means: it has the property of being hardened by being irradiated by active energy rays such as ultraviolet rays and electron beams, and it can make a film with adhesive properties even before the active energy rays are irradiated. Adhesive and has an adhesive composition that is hardened by the irradiation of active energy rays and can adjust the properties of adhesion. The active energy ray-curable adhesive composition is preferably an ultraviolet-curable adhesive composition. The active energy ray-curable adhesive composition may further contain an active energy ray polymerizable compound in addition to the base polymer and crosslinking agent. Furthermore, it may also contain a photopolymerization initiator, photosensitizer, etc. as needed.

In addition to polymers, the adhesive composition may contain solvents; adhesives, softeners, fillers (metal powder or other inorganic powders, etc.), antioxidants, ultraviolet absorbers, dyes, pigments, colorants, defoamers, Additives such as corrosion inhibitors and photopolymerization initiators. In the case of using an active energy ray-curable adhesive composition, the formed adhesive layer is irradiated with active energy rays to obtain a cured product having a desired degree of curing.

The adhesive layer can be formed by coating the organic solvent diluent of the adhesive composition on the substrate and drying it.

When the bonding layer 16 belongs to an adhesive layer, as an adhesive composition used for forming an adhesive layer, if it can satisfy the said moisture permeability, it will not specifically limit. Examples of the adhesive composition include: water-based adhesives, active energy ray-curable adhesives, natural rubber adhesives, α-olefin-based adhesives, urethane resin-based adhesives, and ethylene-vinyl acetate resin emulsions. Adhesives, ethylene-vinyl acetate resin-based hot melt adhesives, epoxy resin-based adhesives, vinyl chloride resin solvent-based adhesives, chloroprene rubber-based adhesives, cyanoacrylate-based adhesives, silicone Adhesives, styrene-butadiene rubber solvent-based adhesives, nitrile rubber-based adhesives, nitrocellulose-based adhesives, reactive hot melt adhesives, phenol resin-based adhesives, modified silicone-based adhesives , Polyester hot melt adhesive, polyamide resin hot melt adhesive, polyimide resin hot melt adhesive, polyurethane resin hot melt adhesive, polyolefin resin hot melt adhesive, polyvinyl acetate resin Solvent adhesive, polystyrene resin solvent adhesive, polyvinyl alcohol adhesive, polyvinylpyrrolidone resin adhesive, polyvinyl butyral adhesive, polybenzimidazole adhesive, polymethacrylic acid Ester resin solvent-based adhesives, melamine resin-based adhesives, urea resin-based adhesives, resorcinol-based adhesives, etc. Such an adhesive can be used individually by 1 type or in mixture of 2 or more types.

Examples of water-based adhesives include polyvinyl alcohol-based resin aqueous solutions, water-based two-component urethane-based emulsion adhesives, and the like. The active energy ray-curable adhesive is an adhesive that is cured by irradiating active energy rays such as ultraviolet rays. Examples thereof include those containing polymerizable compounds and photopolymerizable initiators, those containing photoreactive resins, and those containing adhesives. Agent resin and photoreactive crosslinking agent, etc. Examples of the above-mentioned polymerizable compound include: photocurable epoxy -Based monomers, photo-curable (meth)acrylic monomers, photo-curable urethane-based monomers, and other photopolymerizable monomers, and oligomers derived from these monomers. Examples of the photopolymerization initiator include those containing active species that generate so-called neutral radicals, anionic radicals, and cationic radicals by irradiating active energy rays such as ultraviolet rays.

The thickness of the bonding layer is not particularly limited, but when the bonding layer is an adhesive layer, it is preferably 5 μm or more, may be 15 μm or more, may be 20 μm or more, or may be 25 μm or more, usually 200 μm or less, It may be 100 μm or less, or 50 μm or less. When the bonding layer is an adhesive layer, the thickness of the bonding layer is preferably 0.01 μm or more, may be 0.05 μm or more, or may be 0.5 μm or more, and is preferably 5 μm or less, may be 3 μm or less, or It can be 2μm or less.

<Image Display Panel>

The image display panel 30 is not particularly limited as long as it can be bent, but is preferably an organic electroluminescence (EL) display panel.

<Other layers that the circular polarizing plate 10 may have>

The circularly polarizing plate 10 may have layers other than the above-mentioned layers. The other layers that the circular polarizing plate 10 may have are exemplified below.

(Phase Difference Plate)

The circular polarizing plate 10 may have a λ/2 retardation plate or a positive C layer between the linear polarizing plate 13 and the bonding layer 16. In addition, the circularly polarizing plate 10 may have a positive C layer of another bonding layer on the side opposite to the bonding layer 16 of the λ/4 retardation plate 11. The λ/2 retardation layer or the retardation expression layer of the positive C layer may be a liquid crystal layer containing a cured product of a polymerizable liquid crystal compound, or a resin film. The λ/2 phase difference plate or the positive C layer can be produced by the same method as the λ/4 phase difference plate.

The circular polarizing plate 10 includes an anti-reflection layer 19, a linear polarizing plate 13, and a λ/4 retardation plate 11. As a configuration including a retardation plate other than the λ/4 retardation plate 11, a second configuration is exemplified. Can enumerate: from the front side in order:

i) A composition having an anti-reflection layer 19, a linear polarizing plate 13, a λ/2 phase difference plate, and a λ/4 phase difference plate 11.

ii) A structure having an anti-reflection layer 19, a linear polarizing plate 13, a λ/4 retardation plate 11, a positive C layer, and the like.

(Adhesive layer used for image display panel bonding)

The circular polarizing plate 10 can be configured as a circular polarizing plate with an adhesive layer. The circular polarizing plate with an adhesive layer is provided with an adhesive on the back surface that can be used to attach the circular polarizing plate 10 to the image display panel 30. Agent layer.

(Surface treatment layer)

The linear polarizer 13 may have a surface treatment layer on the surface of the protective film on the front side, and may have, for example, a hard coat layer, an anti-adhesion layer, an anti-glare layer, a diffusion layer, and the like. The surface treatment layer may be another layer laminated on the protective film, or may be formed by performing surface treatment on the surface of the protective film.

<Other layers that the image display device may have>

The image display device 20 may have layers other than those described above. The other layers that the image display device 20 may have are exemplified below.

(Touch sensor panel)

The touch sensor panel is a device (sensor) that detects (senses) a finger or other contact (touch) on the screen of the image display device (sensor), and is used to detect the position of the finger on the screen and input it into the image display device Input means. The touch sensor panel can be arranged between the circular polarizer 10 and the image display panel 30, It may also be arranged on the front side of the circular polarizing plate 10. As the touch sensor panel, as long as it is a sensor that can detect the position to be touched, the detection method is not particularly limited. Examples include: resistive film method, electrostatic capacitance coupling method, photo sensor method, ultrasonic method, Touch sensor panel of electromagnetic induction coupling method, surface elastic wave method, infrared method, etc. In terms of low cost, it is suitable to use touch sensor panels of resistive film method and electrostatic capacitance coupling method.

An example of the touch sensor panel of the resistive film method is by arranging a pair of substrates facing each other, an insulating spacer sandwiched between the pair of substrates, and a front surface of the inner side of each substrate. The transparent conductive film of the resistive film and the tactile position detection circuit are constituted. In an image display device provided with a touch sensor panel of a resistive film method, when the surface of the front panel is touched, the opposing resistive film is short-circuited, and current flows through the resistive film. The tactile position detection circuit detects the voltage change at this time and detects the touched position.

An example of the touch sensor panel of the electrostatic capacitance coupling method is composed of a substrate, a transparent electrode for position detection provided on the entire surface of the substrate, and a tactile position detection circuit. In the image display device provided with the touch sensor panel of the electrostatic capacitance coupling method, when the surface of the front panel is touched, the transparent electrode is grounded through the capacitance of the human body at the touched point. The touch position detection circuit detects the grounding of the transparent electrode and detects the touched position. The capacitive touch sensor panel is divided into an active area and an inactive area located outside the active area. The active area is the area corresponding to the area where the screen is displayed on the display panel (display portion) and the area that senses the user's touch, and the inactive area is the area corresponding to the area where the screen is not displayed on the display device (non-display portion).

The thickness of the touch sensor panel can be, for example, 5 μm or more and 2,000 μm or less, or 5 μm or more and 100 μm or less.

<Flexible image display device>

The image display device may be a flexible image display device. The flexible image display device is a bendable image display device. The flexible image display device includes a bendable image display element incorporating an optical fingerprint authentication system, and the circular polarizing plate of the present invention. The bendable image display element is, for example, an organic EL display panel. The circular polarizing plate of the present invention is arranged on the identification side with respect to the organic EL display panel, and is configured to be bendable. The circular polarizing plate for the flexible image display device may be further equipped with a front panel and a touch sensor panel.

Preferably, the front panel, the circular polarizing plate and the touch sensor panel of the present invention are laminated in order from the recognition side, or the front panel, the touch sensor panel and the circular polarizing plate of the present invention are laminated in order from the recognition side. When the polarizer is on the recognition side of the touch sensor panel, it becomes difficult to recognize the pattern of the touch sensor panel. As a result, the recognition of the displayed image becomes better. Therefore, it is better to have the circular polarizer of the present invention. The structure of the identification side of the touch sensor panel, that is, includes the front panel, the circular polarizing plate of the present invention, and the touch sensor panel in this order. Each member can be laminated using adhesives, adhesives, etc. In addition, it may be provided with a light-shielding pattern formed on at least one surface of any layer of the front panel, the circular polarizing plate, and the touch sensor panel.

In a flexible image display device equipped with a front panel, a circular polarizing plate of the present invention, and a bendable image display element from the recognition side, the front panel and the circular polarizing plate of the present invention are configured with a circular polarizing plate and a front Panel with circular polarizer with front panel. In the circular polarizer with a front panel, the front panel is usually arranged on the identification side of the circular polarizer, and the circular polarizer is laminated by, for example, an adhesive or an adhesive.

In a flexible image display device equipped with a touch sensor panel, the circular polarizing plate of the present invention, and a bendable image display element from the recognition side, the touch sensor panel and the circular polarizing plate of the present invention are constituted A circular polarizing plate with a touch sensor panel with a circular polarizing plate and a touch sensor panel. In addition, in In a flexible image display device having the circular polarizing plate of the present invention, a touch sensor panel, and a bendable image display element from the recognition side, the touch sensor panel and the circular polarizing plate of the present invention are configured with Circular polarizing plate with touch sensor panel and circular polarizing plate with touch sensor panel. In the circular polarizer with a touch sensor panel, the touch sensor panel can be arranged on the back side of the circular polarizer (the side opposite to the recognition side), or on the recognition side of the circular polarizer. The touch sensor panel and the circular polarizing plate are laminated by, for example, adhesives or adhesives.

The circular polarizing plate of the present invention can also be used as a circular polarizing plate with a front panel in which the front panel is laminated on the identification side. The circular polarizing plate with a front panel includes the circular polarizing plate of the present invention and a front panel arranged on the identification side.

(Front panel)

Examples of the front panel include those containing a hard coat layer on at least one surface of glass and resin film. As the glass, for example, high-transmittance glass and strengthened glass can be used. Especially when a thin transparent surface material is used, it is preferably chemically strengthened glass. The thickness of the glass can be set to, for example, 100 μm to 5 mm.

The front panel containing a hard coating on at least one side of the resin film is not as hard as existing glass, but can have flexible properties. The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 to 100 μm.

The resin film may be, for example, a cycloolefin derivative, cellulose (cellulose diacetate, cellulose triacetate, etc.) having monomer units containing cycloolefins such as norbornene and polycyclic norbornene-based monomers. , Cellulose Acetate Butyrate, Cellulose Isobutyl Ester, Cellulose Acetate, Cellulose Butyrate, Cellulose Acetyl Acetate) ethylene-vinyl acetate copolymer, polycyclic olefin, polyester, polystyrene , Polyamide, polyetherimide, polyacrylic acid, polyimide, polyimide, polyetherimine, poly Waste, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether sulfide, polymethyl Films formed by polymers such as methyl acrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, and epoxy. These polymers can be used individually or in combination of two or more.

The resin film may be an unstretched film, and the stretched film may be, for example, a uniaxially stretched film or a biaxially stretched film. The resin film is preferably a polyimide film, polyimide film, uniaxially stretched polyester film, and biaxially stretched polyester film in terms of excellent transparency and heat resistance. In terms of transparency In terms of excellent heat resistance and compatibility with larger films, cycloolefin derivative films and polymethyl methacrylate films are preferred, as it is easier to obtain transparent and non-optically anisotropic resin films. In terms of point, cellulose triacetate and isobutyl cellulose film are respectively preferred. The thickness of the resin film is usually 5 to 200 μm, preferably 20 to 100 μm.

(Shading pattern)

The shading pattern is a member called a bezel, which can be formed on the display element side of the front panel. By having a light-shielding pattern, each wiring constituting the display device can be hidden so that the user cannot recognize it. The color and material of the shading pattern are not particularly limited, and can be formed of resin materials with various colors such as black, white, and gold. In one embodiment, the thickness of the light-shielding 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 bubbles and the recognition of the boundary portion due to the step difference between the light-shielding pattern and the display portion, the light-shielding pattern may be given a shape.

(Touch sensor panel)

The touch sensor panel is as described above. The capacitive touch sensor panel used in the flexible image display device is composed of a substrate with flexible characteristics, a sensing pattern formed on the active area of the substrate, and the inactive area of the substrate. It includes each sensing line for connecting to an external driving circuit via the aforementioned sensing pattern and the pad portion. As a substrate having flexibility, the same material as the resin film of the aforementioned front panel can be used. For the substrate of the touch sensor panel, from the viewpoint of suppressing the chipping that can be generated in the touch sensor panel, a toughness of 2,000 MPa% or more is preferable. More preferably, the toughness is 2,000MPa% to 30,000MPa%. Here, the toughness system is defined as the area of the lower part of the curve up to the failure point in the stress-strain (%) curve obtained through the tensile test of the polymer material.

[Example]

Hereinafter, examples and comparative examples are presented to explain the present invention more specifically, but the present invention is not limited to these examples. The blending amounts indicated by "%" and "parts" in the examples and comparative examples are mass% and mass parts unless otherwise stated.

<Production of Circular Polarizing Plate A with Adhesive Layer>

The first polarizer protective film was bonded to one side of a polarizer with a thickness of 12 μm via a water-based adhesive. The second polarizer protective film was bonded to the other side of the polarizer via a water-based adhesive to obtain a linear polarizer. On the second polarizer protective film side of the linear polarizer, the λ/4 retardation plate is placed at 45° clockwise with respect to the absorption axis of the polarizer, and the positive C layer is bonded to the film via the UV adhesive layer. Laminate the adhesive layer A on the surface of the λ/4 retardation plate opposite to the side of the linear polarizer on the surface of the positive C layer on the side opposite to the λ/4 retardation plate side, and further laminate the isolation film. It is aged for 1 week at 40°C and 55% to obtain a laminate with an adhesive layer.

On the surface of the laminated body with the adhesive layer on the opposite side of the adhesive layer A, a cellulose triacetate film provided with an anti-reflection layer is attached so that the anti-reflection layer is outside, and the adhesive layer is interposed. , And make circular polarizer A with adhesive layer.

Prepare the components used in the production of the circular polarizing plate with the adhesive layer in the following steps.

<Production of Polarizer>

A polyvinyl alcohol film with a thickness of 30 μm (average degree of polymerization of about 2,400, degree of saponification of 99.9 mol% or more) was uniaxially stretched about 5 times by dry stretching, and then immersed in pure water at 60°C for 1 minute under tension. Immerse in an aqueous solution with a weight ratio of iodine/potassium iodide/water of 0.05/5/100 at 28°C for 60 seconds. Thereafter, it was immersed in an aqueous solution with a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 at 72°C for 300 seconds. Then, it was washed with pure water at 26° C. for 20 seconds and dried at 65° C. to obtain a 12 μm-thick polarizer with iodine adsorbed and aligned on the polyvinyl alcohol film. The thickness of the polarizer was measured with a contact film thickness meter (trade name "DIGIMICRO (registered trademark) MH-15M" manufactured by Nikon Co., Ltd.).

<Preparation of Aqueous Adhesive>

With respect to 100 parts by weight of water, 3 parts by weight of carboxyl modified polyvinyl alcohol [trade name "KL-318" obtained from Kuraray Co., Ltd.] are dissolved, and a polyamide ring, which is a water-soluble epoxy resin, is added to the aqueous solution. Oxygen-based additives [trade name "Sumirez Resin (registered trademark) 650(30)" obtained from Taoka Chemical Industry Co., Ltd., aqueous solution with a solid concentration of 30% by weight) 1.5 parts by weight, to prepare a water-based adhesive.

<Preparation of the first polarizer protective film>

Prepared diagonally stretched polyolefin film with hard coat made by Nippon Paper Co., Ltd. The thickness of the film is 29 μm.

<Preparation of the second polarizer protective film>

A cellulose triacetate membrane (trade name: KC2CT) manufactured by KONICA MINOLTA Co., Ltd. was prepared. The thickness of the film is 20 μm.

<Making of λ/4 retardation plate/positive C layer>

(Preparation of composition (1) for forming photo-alignment layer)

The following components were mixed, and the obtained mixture was stirred at a temperature of 80° C. for 1 hour to obtain a composition (1) for forming a photo-alignment layer.

‧Optical alignment material (5 copies):

‧Solvent (95 parts): Cyclopentanone

(Preparation of composition (2) for formation of alignment layer)

To SUNEVER SE-610 (manufactured by Nissan Chemical Industry Co., Ltd.) which is a commercially available alignment polymer, 2-butoxyethanol was added to obtain an alignment layer forming composition (2). The obtained composition (2) for forming an alignment layer has a solid content ratio of 1% relative to the total amount of the composition, and a solvent content ratio of 99% relative to the total amount of the composition. The solid content of SUN EVER SE-610 is converted from the concentration stated in the delivery specifications.

(Preparation of liquid crystal layer forming composition (A-1))

The following components were mixed, and the obtained mixture was stirred at 80°C for 1 hour to obtain a composition (A-1) for forming a liquid crystal layer. The polymerizable liquid crystal compound A1 and the polymerizable liquid crystal compound A2 were synthesized by the method described in JP 2010-31223 A.

‧Polymerizable liquid crystal compound A1 (80 parts):

‧Polymerizable liquid crystal compound A2 (20 parts):

‧Polymerization initiator (6 parts):

2-Dimethylamino-2-benzyl _[u1] yl-1-(4-morpholinylphenyl)butan-1-one (Irgacure 369; manufactured by Ciba Specialty Chemicals)

‧Solvent (400 parts): Cyclopentanone

(Preparation of liquid crystal layer formation composition (B-1))

The following components were mixed, and the obtained mixture was stirred at 80°C for 1 hour, and then cooled to room temperature to obtain a composition (B-1) for forming a liquid crystal layer.

‧Polymerizable liquid crystal compound LC242 (manufactured by BASF) (19.2%):

‧Polymerization initiator (0.5%):

Irgacure (registered trademark) 907 (made by BASF Japan)

‧Reactive additives (1.1%):

Laromer (registered trademark) LR-9000 (made by BASF Japan)

‧Solvent (79.1%): propylene glycol 1-monomethyl ether 2-acetate

(Making of λ/4 retardation plate)

A corona treatment device (AGF-B10, manufactured by Kasuga Electric Co., Ltd.) was used to process a polyethylene terephthalate (PET) film with a thickness of 100 μm under the conditions of an output of 0.3 kW and a processing speed of 3 m/min. 1 time. On the corona-treated surface, the photo-alignment layer forming composition (1) was coated with a coating bar, dried at 80°C for 1 minute, and a polarized UV irradiation device (SPOT CURE SP-7; USHIO Electric Co., Ltd. Co., Ltd.) was subjected to polarized UV exposure with a cumulative light amount of ^{100 mJ/cm 2 to obtain a photo-alignment layer.} The thickness of the obtained photo-alignment layer was measured with a laser microscope (LEXT, manufactured by Olympus Co., Ltd.), and the thickness was 100 nm.

Then, the liquid crystal layer forming composition (A-1) was coated on the photo-alignment layer using a coating bar, and after drying at 120°C for 1 minute, a high-pressure mercury lamp (Unicure VB-15201BY-A, USHIO Electric Co., Ltd.) was used. Co., Ltd.) The λ/4 retardation plate is obtained by forming a retardation expression layer by ultraviolet light (in a nitrogen environment, wavelength: 365nm, cumulative light quantity in a wavelength of 365nm: 1000mJ/cm ^{2 ).} The thickness of the retardation expression layer in the λ/4 retardation plate was measured with a laser microscope (LEXT, manufactured by Olympus Co., Ltd.), and the thickness was 2 μm.

The in-plane retardation value of the λ/4 retardation plate was measured with a retardation measuring device [Oji Measuring Instruments "KOBRA-WR"], and the in-plane retardation value Re(550) at a wavelength of 550nm was 142nm.

(Production of positive C layer)

Using a corona treatment device (AGF-B10, manufactured by Kasuga Electric Co., Ltd.) under the conditions of an output of 0.3 kW and a processing speed of 3 m/min, a polyethylene terephthalate (PET) film with a thickness of 38 μm was processed. Times processing. On the surface subjected to the corona treatment, the alignment layer forming composition (2) was coated with a coating bar, and dried at 90° C. for 1 minute to obtain an alignment layer. The thickness of the obtained alignment layer was measured with a laser microscope (LEXT, manufactured by Olympus Co., Ltd.), and the thickness was 34 nm.

Next, the liquid crystal layer forming composition (B-1) was coated on the alignment layer using a coating bar, and after drying at 90°C for 1 minute, a high-pressure mercury lamp (Unicure VB-15201BY-A, USHIO Electric Co., Ltd. (Incorporated) The positive C layer is obtained by irradiating ultraviolet rays (in a nitrogen environment, wavelength: 365nm, cumulative light quantity in a wavelength of 365nm: 1000mJ/cm ² ) to form a phase difference expression layer. The thickness of the phase difference expression layer in the positive C layer was measured with a laser microscope (LEXT, manufactured by Olympus Co., Ltd.), and the thickness was 1 μm. The thickness direction retardation value of the positive C layer was measured by a retardation measuring device [Oji Measuring Instruments "KOBRA-WR"], and the thickness direction retardation value at a wavelength of 550nm was -75nm.

(Making of Adhesive Layer A)

With respect to 100 parts of the solid content of acrylic resin solution 1, 0.6 part of Coronate HXR (manufactured by Tosoh Corporation) as a crosslinking agent and 0.5 part of KBM-403 (manufactured by Shin-Etsu Polysiloxane Co., Ltd.) as a silane coupling agent are prepared. And will be used as an antistatic agent of double (trifluoromethanesulfonyl) sub Lithium amide (sometimes referred to as LiTSFI), and tetraethylene glycol dimethyl ether (TGR) as a dispersing aid are formulated into 3.0 parts by weight through a molar formula. Furthermore, methyl ethyl ketone was added so that the solid content concentration became 14%, and the adhesive composition A was prepared using a blender ("Three-one-motor" manufactured by Yamato Scientific Co., Ltd.) at 300 rpm for 30 minutes. Using an applicator, the adhesive composition A was applied to the release-treated polyethylene terephthalate film [LINTEC (stock) trade name "SP" so that the thickness of the adhesive layer after drying became 20 μm). -PLR382190", also called a release film] The release treatment surface was dried at 100°C for 1 minute to prepare an adhesive layer A.

(Preparation of isolation film)

Prepare LINTEC Co., Ltd. SP-PLR382190 as the isolation membrane.

<Production of Circular Polarizing Plate B with Adhesive Layer>

In the production of the λ/4 retardation plate shown above, in addition to changing the coating thickness of the liquid crystal layer forming composition (A-1), and the λ/ in the production of the circular polarizing plate A with the adhesive layer The production of the 4-phase difference plate was performed in the same manner to obtain a λ/4 phase difference plate. The in-plane retardation value of the λ/4 retardation plate was measured with a retardation measuring device [Oji Measuring Instruments "KOBRA-WR"], and the in-plane retardation value Re(550) at a wavelength of 550 nm was 140 nm. As the λ/4 retardation plate, except for the use of these points, the adhesive layer-attached circular polarizing plate B was produced in the same manner as the adhesive layer-attached circular polarizing plate A.

[Test Example A]

Cut a rectangular (short side 150mm, width 200mm) test piece from the circular polarizer A with the adhesive layer. At this time, the short-side direction (consistent with the direction of the bending center line C in the image display device) and the angle θ between the slow axis of the λ/4 retardation plate are 0°, 45°, and 90° It is cut into 3 types of test pieces.

As shown in Fig. 5, the test piece 42 cut at a specified angle is bonded to an acrylic plate (thickness 1mm, rectangular (short side 200mm, long side 300mm), manufactured by Sumitomo Chemical Co.), laminated with aluminum foil via the adhesive layer A. The reflector 41 is placed in an environment of 23°C and a relative humidity of 55% for 24 hours so that the short-side direction of the acrylic plate is consistent with the short-side direction of the sample to obtain a measurement sample 40.

Using a spectrophotometer (manufactured by KONICA MINOLTA Co., Ltd., product name: CM2600d), light from the D65 light source is irradiated from the front side to the area near the center line C of the measurement sample 40, and the reflected light reflected by the measurement sample 40 is measured The hue value of (a*(D65), b*(D65)).

The measurement of the measurement sample 40 is performed in a flat state and in a bent state along the center line C. In addition, with respect to the bent state, the entire test piece was irradiated with light, and the hue of the reflected light reflected from the test piece was visually confirmed, and the evaluation was made based on the following criteria. The results are shown in Table 1. In addition, in Table 1, the plane state is shown as "flat", and the bending state along the center line C is shown as "bending".

1: The hue of the reflected light is uniform.

2: The reflected light is a mixture of red and blue light.

6(a) and (b) are simplified diagrams showing the positional relationship between the measurement sample 40 and the spectrophotometer 50 in the measurement device. Fig. 6(a) is a schematic diagram showing the positional relationship when the measurement sample 40 is in a flat state, and Fig. 6(b) shows the measurement sample 40 is in a bent state along the center line C as the inner side of the test piece 42 A simplified diagram of the positional relationship in the situation. In FIG. 6(b), the short sides of the acrylic plate in the measurement sample 40 that are opposed to each other are joined in parallel with each other by a cloth adhesive tape, so that the measurement sample 40 is bent. The distance between the short sides of the acrylic resin board is 248 mm. The curved measurement sample 40 is a square whose radius of curvature gradually increases from the vicinity of the center line C to the short sides. 式flexion. In the bent measurement sample, the area at a distance of 100 mm or more from the center line C and the area near the short side are approximately flat. It can be considered that the reflected light emitted from the substantially flat area matches the color of the reflected light emitted from the vicinity of the center line C in the planar state shown in FIG. 6(a).

[Test Example B]

Except for the point where the test piece was cut from the circular polarizer B with the adhesive layer, the hue value (a*(D65), b*(D65)) was measured in the same manner as in Test Example A, and the reflected light was visually confirmed Hue.

The results are shown in Table 1.

[Table 1]

For a*(D65) of the hue shown in Table 1, it becomes a blue hue when it belongs to a negative value, and it becomes a red hue when it belongs to a positive value. In Test Examples A and B, only when the θ of Test Example B is 90°, the hue of the reflected light detected by comparing the flat state and the bent state changes from a blue hue to a red hue, and the result of the visual evaluation is "2" . In addition, the hue of the reflected light detected at the same time in the flat state and the bent state is a blue hue, and the result of the visual evaluation is "1". When the θ of Test Example B is 90°, in the bent state, the hue of the reflected light from the area near the center line is red. It can be considered that the hue of the reflected light from other areas is the same as the flat state and blue. Therefore, It is assumed that the result of visual evaluation is "2".

10: Circular polarizing plate

11: λ/4 phase difference plate

13: Linear polarizer

16: Laminated layer

19: Anti-reflective layer

Claims (9)

A circular polarizing plate, which can be bent for users, and has in order: Anti-reflection layer, linear polarizing plate, and λ/4 retardation plate; among them, The aforementioned λ/4 retardation plate system: when the in-plane retardation value at a wavelength of 550nm is set to Re(550)[nm], Re(550) satisfies the relationship of formula (1a) or formula (2a), 141nm≦Re(550)≦180nm (1a) 95nm≦Re(550)≦134nm (2a). A circular polarizer that can be bent along the bending centerline, and has in order: Anti-reflection layer, linear polarizing plate, and λ/4 retardation plate; among them, The aforementioned λ/4 retardation plate system: when the in-plane retardation value at a wavelength of 550nm is set to Re(550)[nm], Re(550) satisfies the relationship of formula (1b) or formula (2b), 138nm≦Re(550)<141nm (1b) 134nm<Re(550)≦137nm (2b) The slow axis of the aforementioned λ/4 retardation plate is bent and used so that the included angle with the aforementioned bending center line becomes 70° or less. The circularly polarizing plate according to claim 1 or 2, wherein the λ/4 retardation plate has reverse wavelength dispersion. The circularly polarizing plate according to any one of claims 1 to 3, wherein the λ/4 retardation plate has a retardation expression layer containing a cured product of a polymerizable liquid crystal compound. The circular polarizing plate according to claim 4, wherein the thickness of the retardation expression layer is 0.5 μm or more and 10 μm or less. A circular polarizing plate with a front panel is provided with the circular polarizing plate according to any one of claims 1 to 5, and a front panel. A circular polarizing plate with a touch sensor panel is provided with the circular polarizing plate according to any one of claims 1 to 5, and a touch sensor panel. An image display device comprising: an image display panel, and a circular polarizer as described in any one of claims 1 to 5 arranged on the front side of the aforementioned image display panel, or as described in claim 6 The circular polarizing plate with the front panel, or the circular polarizing plate as described in claim 7. The image display device according to claim 8, wherein the image display panel is an organic electroluminescence display panel.

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